Genomic Inbreeding and Relatedness in Wild Panda Populations

Science.gov (United States)

Da, Yang

2016-01-01

Inbreeding and relatedness in wild panda populations are important parameters for panda conservation. Habitat loss and fragmentation are expected to increase inbreeding but the actual inbreeding levels in natural panda habitats were unknown. Using 150,025 SNPs and 14,926 SNPs selected from published whole-genome sequences, we estimated genomic inbreeding coefficients and relatedness of 49 pandas including 34 wild pandas sampled from six habitats. Qinling and Liangshan pandas had the highest levels of inbreeding and relatedness measured by genomic inbreeding and coancestry coefficients, whereas the inbreeding levels in Qionglai and Minshan were 28–45% of those in Qinling and Liangshan. Genomic coancestry coefficients between pandas from different habitats showed that panda populations from the four largest habitats, Minshan, Qionglai, Qinling and Liangshan, were genetically unrelated. Pandas between these four habitats on average shared 66.0–69.1% common alleles and 45.6–48.6% common genotypes, whereas pandas within each habitat shared 71.8–77.0% common alleles and 51.7–60.4% common genotypes. Pandas in the smaller populations of Qinling and Liangshan were more similarly to each other than pandas in the larger populations of Qionglai and Minshan according to three genomic similarity measures. Panda genetic differentiation between these habitats was positively related to their geographical distances. Most pandas separated by 200 kilometers or more shared no common ancestral alleles. The results provided a genomic quantification of the actual levels of inbreeding and relatedness among pandas in their natural habitats, provided genomic confirmation of the relationship between genetic diversity and geographical distances, and provided genomic evidence to the urgency of habitat protection. PMID:27494031

No Inbreeding depression for low temperature developmental acclimation across multiple drosophila species

DEFF Research Database (Denmark)

Kristensen, Torsten Nygård; Loeschcke, Volker; Bilde, Trine

2011-01-01

stressful temperatures, but whether adaptation to thermal stress through plastic responses also is affected by inbreeding is so far not clear. In this study, we test inherent cold resistance and the ability to respond plastically to temperature changes through developmental cold acclimation in inbred...... the ability to respond adaptively to temperature acclimation, and (3) tropical species with low basal resistance show stronger adaptive plastic responses to developmental acclimation compared to widespread species...

Life history correlates of inbreeding depression in mandrills (Mandrillus sphinx).

Science.gov (United States)

Charpentier, M; Setchell, J M; Prugnolle, F; Wickings, E J; Peignot, P; Balloux, F; Hossaert-McKey, M

2006-01-01

Inbreeding depression reflects the negative consequences of increased homozygosity at genes that affect fitness. We investigate inbreeding depression in a semi-free-ranging colony of mandrills (Mandrillus sphinx), using high-quality pedigree data, comprising five maternal generations and 20 years of morphological and demographic data. We examine the relationship between inbreeding coefficients and four fitness correlates: two growth parameters (mass and height for age) and longevity in both sexes, and age at first conception in females. Inbreeding was correlated with both growth parameters, but only in females, with inbred females being smaller than noninbred females. Inbreeding was also correlated significantly with age at first conception, with inbred females giving birth earlier in life than noninbred females. We suggest that sex-biased maternal investment may explain this sex-differential response to inbreeding, although the lack of a significant association between inbreeding and growth in males may also be due to the provisioned nature of the colony. The surprising relationship between age at first conception and inbreeding may be related to smaller adult size in inbred females, or to their being less able to escape from male sexual coercion.

Genomic dissection of inbreeding depression: a gate to new opportunities

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Ino Curik

Full Text Available ABSTRACT Inbreeding depression, reduction in performance of quantitative traits, including reproduction and survival, caused by inbreeding, is a well-known phenomenon observed in almost all experimental, domesticated, and natural populations. In spite of its importance to the fate of a small population and numerous research performed in the last century, the genetic basis of inbreeding depression is still unclear. Recent fast development of molecular techniques has enabled estimation of a genomic inbreeding coefficient (FROH, which reflects realized autozygosity and can be further partitioned to chromosomes and chromosomal segments. In this review, we first describe classical approach used in the estimation of inbreeding in livestock populations, followed by early concepts of replacing pedigree inbreeding coefficient by individual heterozygosity. Then, we explain runs of homozygosity as key approach in estimating realized autozygosity. Furthermore, we present two different concepts of analysing regions that substantially contribute to the inbreeding depression. Thus, we describe how to identify or map mutations that result in the reduction of performance and, in terms of quantitative genetics, how to analyse the architecture of inbreeding depression. At the end, we discuss future perspectives in eliminating deleterious mutations from livestock populations.

Parental care buffers against inbreeding depression in burying beetles.

Science.gov (United States)

Pilakouta, Natalie; Jamieson, Seonaidh; Moorad, Jacob A; Smiseth, Per T

2015-06-30

When relatives mate, their inbred offspring often suffer a reduction in fitness-related traits known as "inbreeding depression." There is mounting evidence that inbreeding depression can be exacerbated by environmental stresses such as starvation, predation, parasitism, and competition. Parental care may play an important role as a buffer against inbreeding depression in the offspring by alleviating these environmental stresses. Here, we examine the effect of parental care on the fitness costs of inbreeding in the burying beetle Nicrophorus vespilloides, an insect with facultative parental care. We used a 2 × 2 factorial design with the following factors: (i) the presence or absence of a caring female parent during larval development and (ii) inbred or outbred offspring. We examined the joint influence of maternal care and inbreeding status on fitness-related offspring traits to test the hypothesis that maternal care improves the performance of inbred offspring more than that of outbred offspring. Indeed, the female's presence led to a higher increase in larval survival in inbred than in outbred broods. Receiving care at the larval stage also increased the lifespan of inbred but not outbred adults, suggesting that the beneficial buffering effects of maternal care can persist long after the offspring have become independent. Our results show that parental care has the potential to moderate the severity of inbreeding depression, which in turn may favor inbreeding tolerance and influence the evolution of mating systems and other inbreeding-avoidance mechanisms.

Closed-loop multiple antenna aided wireless communications using limited feedback

OpenAIRE

Yang, Du

2010-01-01

The aim of this thesis is to study the design of closed-loop multiple antenna aided wireless communications relying on limited feedback. Multiple antennas may be employed either/both at the transmitter or/and at the receiver, here the latter periodically feeds back some information about the time-varying wireless channel using a limited number of bits. Furthermore, the transmitter then pre-processes the signals to be transmitted according to the received feedback information. This closed-loop...

Evaluation of inbreeding depression in Holstein cattle using whole-genome SNP markers and alternative measures of genomic inbreeding.

Science.gov (United States)

Bjelland, D W; Weigel, K A; Vukasinovic, N; Nkrumah, J D

2013-07-01

The effects of increased pedigree inbreeding in dairy cattle populations have been well documented and result in a negative impact on profitability. Recent advances in genotyping technology have allowed researchers to move beyond pedigree analysis and study inbreeding at a molecular level. In this study, 5,853 animals were genotyped for 54,001 single nucleotide polymorphisms (SNP); 2,913 cows had phenotypic records including a single lactation for milk yield (from either lactation 1, 2, 3, or 4), reproductive performance, and linear type conformation. After removing SNP with poor call rates, low minor allele frequencies, and departure from Hardy-Weinberg equilibrium, 33,025 SNP remained for analyses. Three measures of genomic inbreeding were evaluated: percent homozygosity (FPH), inbreeding calculated from runs of homozygosity (FROH), and inbreeding derived from a genomic relationship matrix (FGRM). Average FPH was 60.5±1.1%, average FROH was 3.8±2.1%, and average FGRM was 20.8±2.3%, where animals with larger values for each of the genomic inbreeding indices were considered more inbred. Decreases in total milk yield to 205d postpartum of 53, 20, and 47kg per 1% increase in FPH, FROH, and FGRM, respectively, were observed. Increases in days open per 1% increase in FPH (1.76 d), FROH (1.72 d), and FGRM (1.06 d) were also noted, as well as increases in maternal calving difficulty (0.09, 0.03, and 0.04 on a 5-point scale for FPH, FROH, and FGRM, respectively). Several linear type traits, such as strength (-0.40, -0.11, and -0.19), rear legs rear view (-0.35, -0.16, and -0.14), front teat placement (0.35, 0.25, 0.18), and teat length (-0.24, -0.14, and -0.13) were also affected by increases in FPH, FROH, and FGRM, respectively. Overall, increases in each measure of genomic inbreeding in this study were associated with negative effects on production and reproductive ability in dairy cows. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc

Research on inbreeding in the 'omic' era

DEFF Research Database (Denmark)

Kristensen, Torsten N; Pedersen, Kamilla S; Vermeulen, Cornelis J

2010-01-01

Developments in molecular and systems biology have enabled novel approaches to be used in the study of inbreeding. Mechanistic and functional studies using ‘omic' technologies can increase the understanding of the consequences of inbreeding, from the level of DNA to that of population growth...

Redoable Tie-Over Dressing Using Multiple Loop Silk Threads

Directory of Open Access Journals (Sweden)

Hyeon Jong Jo

2013-05-01

Full Text Available After skin grafting, to prevent hematoma or seroma collection at the graft site, a tie-over dressing has been commonly used. However, although the conventional tie-over dressing by suture is a useful method for securing a graft site, refixation is difficult when repeated tie-over dressing is needed. Therefore, we recommend a redoable tie-over dressing technique with multiple loops threads and connecting silk threads. After the raw surface of each of our cases was covered with a skin graft, multiple loop silk thread attached with nylon at the skin graft margin. We applied the ointment gauze and wet cotton/fluffy gauze over the skin graft, then fixed the dressing by connecting cross-counter multiple loop thread with connecting silk threads. When we opened the tie-over dressing by cutting the connecting silk threads, we repeated the tie-over dressing with the same method. The skin graft was taken successfully without hematoma or seroma collection or any other complications. In conclusion, we report a novel tie-over dressing enabling simple fixation of the dressing to maintain proper tension for wounds that require repetitive fixation. Further, with this reliable method, the skin grafts were well taken.

Redoable Tie-Over Dressing Using Multiple Loop Silk Threads

Directory of Open Access Journals (Sweden)

Hyeon Jong Jo

2013-05-01

Full Text Available After skin grafting, to prevent hematoma or seroma collection at the graft site, a tie-over dressing has been commonly used. However, although the conventional tie-over dressing by suture is a useful method for securing a graft site, refixation is difficult when repeated tieover dressing is needed. Therefore, we recommend a redoable tie-over dressing technique with multiple loops threads and connecting silk threads. After the raw surface of each of our cases was covered with a skin graft, multiple loop silk thread attached with nylon at the skin graft margin. We applied the ointment gauze and wet cotton/fluffy gauze over the skin graft, then fixed the dressing by connecting cross-counter multiple loop thread with connecting silk threads. When we opened the tie-over dressing by cutting the connecting silk threads, we repeated the tie-over dressing with the same method. The skin graft was taken successfully without hematoma or seroma collection or any other complications. In conclusion, we report a novel tie-over dressing enabling simple fixation of the dressing to maintain proper tension for wounds that require repetitive fixation. Further, with this reliable method, the skin grafts were well taken.

The environmental dependence of inbreeding depression in a wild bird population.

Directory of Open Access Journals (Sweden)

Marta Szulkin

2007-10-01

Full Text Available Inbreeding depression occurs when the offspring produced as a result of matings between relatives show reduced fitness, and is generally understood as a consequence of the elevated expression of deleterious recessive alleles. How inbreeding depression varies across environments is of importance for the evolution of inbreeding avoidance behaviour, and for understanding extinction risks in small populations. However, inbreeding-by-environment (IxE interactions have rarely been investigated in wild populations.We analysed 41 years of breeding events from a wild great tit (Parus major population and used 11 measures of the environment to categorise environments as relatively good or poor, testing whether these measures influenced inbreeding depression. Although inbreeding always, and environmental quality often, significantly affected reproductive success, there was little evidence for statistically significant I x E interactions at the level of individual analyses. However, point estimates of the effect of the environment on inbreeding depression were sometimes considerable, and we show that variation in the magnitude of the I x E interaction across environments is consistent with the expectation that this interaction is more marked across environmental axes with a closer link to overall fitness, with the environmental dependence of inbreeding depression being elevated under such conditions. Hence, our analyses provide evidence for an environmental dependence of the inbreeding x environment interaction: effectively an I x E x E.Overall, our analyses suggest that I x E interactions may be substantial in wild populations, when measured across relevant environmental contrasts, although their detection for single traits may require very large samples, or high rates of inbreeding.

Mating system and ploidy influence levels of inbreeding depression in Clarkia (Onagraceae).

Science.gov (United States)

Barringer, Brian C; Geber, Monica A

2008-05-01

Inbreeding depression is the reduction in offspring fitness associated with inbreeding and is thought to be one of the primary forces selecting against the evolution of self-fertilization. Studies suggest that most inbreeding depression is caused by the expression of recessive deleterious alleles in homozygotes whose frequency increases as a result of self-fertilization or mating among relatives. This process leads to the selective elimination of deleterious alleles such that highly selfing species may show remarkably little inbreeding depression. Genome duplication (polyploidy) has also been hypothesized to influence levels of inbreeding depression, with polyploids expected to exhibit less inbreeding depression than diploids. We studied levels of inbreeding depression in allotetraploid and diploid species of Clarkia (Onagraceae) that vary in mating system (each cytotype was represented by an outcrossing and a selfing species). The outcrossing species exhibited more inbreeding depression than the selfing species for most fitness components and for two different measures of cumulative fitness. In contrast, though inbreeding depression was generally lower for the polyploid species than for the diploid species, the difference was statistically significant only for flower number and one of the two measures of cumulative fitness. Further, we detected no significant interaction between mating system and ploidy in determining inbreeding depression. In sum, our results suggest that a taxon's current mating system is more important than ploidy in influencing levels of inbreeding depression in natural populations of these annual plants.

Challenges in LCA modelling of multiple loops for aluminium cans

DEFF Research Database (Denmark)

Niero, Monia; Olsen, Stig Irving

considered the case of closed-loop recycling for aluminium cans, where body and lid are different alloys, and discussed the abovementioned challenge. The Life Cycle Inventory (LCI) modelling of aluminium processes is traditionally based on a pure aluminium flow, therefore neglecting the presence of alloying...... elements. We included the effect of alloying elements on the LCA modelling of aluminium can recycling. First, we performed a mass balance of the main alloying elements (Mn, Fe, Si, Cu) in aluminium can recycling at increasing levels of recycling rate. The analysis distinguished between different aluminium...... packaging scrap sources (i.e. used beverage can and mixed aluminium packaging) to understand the limiting factors for multiple loop aluminium can recycling. Secondly, we performed a comparative LCA of aluminium can production and recycling in multiple loops considering the two aluminium packaging scrap...

Maternal effects alter the severity of inbreeding depression in the offspring.

Science.gov (United States)

Pilakouta, Natalie; Smiseth, Per T

2016-09-14

A maternal effect is a causal influence of the maternal phenotype on the offspring phenotype over and above any direct effects of genes. There is abundant evidence that maternal effects can have a major impact on offspring fitness. Yet, no previous study has investigated the potential role of maternal effects in influencing the severity of inbreeding depression in the offspring. Inbreeding depression is a reduction in the fitness of inbred offspring relative to outbred offspring. Here, we tested whether maternal effects due to body size alter the magnitude of inbreeding depression in the burying beetle Nicrophorus vespilloides We found that inbreeding depression in larval survival was more severe for offspring of large females than offspring of small females. This might be due to differences in how small and large females invest in an inbred brood because of their different prospects for future breeding opportunities. To our knowledge, this is the first evidence for a causal effect of the maternal phenotype on the severity of inbreeding depression in the offspring. In natural populations that are subject to inbreeding, maternal effects may drive variation in inbreeding depression and therefore contribute to variation in the strength and direction of selection for inbreeding avoidance. © 2016 The Author(s).

Variability of individual genetic load: consequences for the detection of inbreeding depression.

Science.gov (United States)

Restoux, Gwendal; Huot de Longchamp, Priscille; Fady, Bruno; Klein, Etienne K

2012-03-01

Inbreeding depression is a key factor affecting the persistence of natural populations, particularly when they are fragmented. In species with mixed mating systems, inbreeding depression can be estimated at the population level by regressing the average progeny fitness by the selfing rate of their mothers. We applied this method using simulated populations to investigate how population genetic parameters can affect the detection power of inbreeding depression. We simulated individual selfing rates and genetic loads from which we computed fitness values. The regression method yielded high statistical power, inbreeding depression being detected as significant (5 % level) in 92 % of the simulations. High individual variation in selfing rate and high mean genetic load led to better detection of inbreeding depression while high among-individual variation in genetic load made it more difficult to detect inbreeding depression. For a constant sampling effort, increasing the number of progenies while decreasing the number of individuals per progeny enhanced the detection power of inbreeding depression. We discuss the implication of among-mother variability of genetic load and selfing rate on inbreeding depression studies.

Effects of Offspring and Parental Inbreeding on Parent-Offspring Communication.

Science.gov (United States)

Mattey, Sarah N; Richardson, Jon; Ratz, Tom; Smiseth, Per T

2018-06-01

There is mounting evidence that inbreeding can have complex effects on social interactions among inbred and outbred individuals. Here, we investigate effects of offspring and maternal inbreeding on parent-offspring communication in the burying beetle Nicrophorus vespilloides. We find effects of the interaction between offspring and maternal inbreeding on maternal behavior. Outbred females provided more direct care toward inbred larvae, while inbred females provided similar levels of direct care toward inbred and outbred larvae. Furthermore, we find direct and indirect effects of offspring inbreeding on offspring begging and maternal behavior, respectively. Inbred larvae spent less time begging than outbred larvae, and (outbred) females provided more direct care and less indirect care toward inbred larvae. Finally, we find effects of the interaction between offspring and maternal inbreeding on larval body mass. Inbred and outbred offspring grew to a similar size when the female was outbred, while inbred offspring were of a smaller size when the female was inbred. Our results suggest that outbred females provided more care toward inbred offspring to compensate for their poor genetic quality. Our study advances our understanding of inbreeding by showing that inbreeding can have direct effects on the behavior of inbred individuals and indirect effects on the behavior of outbred individuals and that indirect effects on outbred individuals may in turn influence the fitness of inbred individuals.

Academic Inbreeding and Publication Activities of Russian Faculty

Science.gov (United States)

Alipova, Olga; Lovakov, Andrey

2018-01-01

The literature on the consequences of academic inbreeding shows ambiguous results: some papers show that inbreeding positively influences research productivity measured by the quantity and quality of publications, while others demonstrate the opposite effect. There are contradictory results both in the studies of different countries and within…

Higher levels of multiple paternities increase seedling survival in the long-lived tree Eucalyptus gracilis.

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Martin F Breed

Full Text Available Studying associations between mating system parameters and fitness in natural populations of trees advances our understanding of how local environments affect seed quality, and thereby helps to predict when inbreeding or multiple paternities should impact on fitness. Indeed, for species that demonstrate inbreeding avoidance, multiple paternities (i.e. the number of male parents per half-sib family should still vary and regulate fitness more than inbreeding--named here as the 'constrained inbreeding hypothesis'. We test this hypothesis in Eucalyptus gracilis, a predominantly insect-pollinated tree. Fifty-eight open-pollinated progeny arrays were collected from trees in three populations. Progeny were planted in a reciprocal transplant trial. Fitness was measured by family establishment rates. We genotyped all trees and their progeny at eight microsatellite loci. Planting site had a strong effect on fitness, but seed provenance and seed provenance × planting site did not. Populations had comparable mating system parameters and were generally outcrossed, experienced low biparental inbreeding and high levels of multiple paternity. As predicted, seed families that had more multiple paternities also had higher fitness, and no fitness-inbreeding correlations were detected. Demonstrating that fitness was most affected by multiple paternities rather than inbreeding, we provide evidence supporting the constrained inbreeding hypothesis; i.e. that multiple paternity may impact on fitness over and above that of inbreeding, particularly for preferentially outcrossing trees at life stages beyond seed development.

Revealing gene action for production characteristics by inbreeding ...

African Journals Online (AJOL)

Revealing gene action for production characteristics by inbreeding, based on a long-term selection ... The gene action involved in the expression of production characters was investigated, using the effect of the theoretical inbreeding ..... and predicted selection responses for growth, fat and lean traits in mice. J. Anim. Sci.

Countering inbreeding with migration 1. Migration from unrelated ...

African Journals Online (AJOL)

Ret:ieved 6 Octoher 1991; ut:cepted I8 Mur- 1995. The eff'ect of migration on inbreeding is moclelled fbr small populations with immigrants from a large unrelated population. Different migration rates and numbers fbr the two sexes are assumed, and a general recursion equation for inbreeding progress derived, which can ...

Inbreeding and fertility in Irish Wolfhounds in Sweden: 1976 to 2007

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Urfer Silvan R

2009-05-01

Full Text Available Abstract Background Given that no influence of inbreeding on life expectancy could be demonstrated in Irish Wolfhounds in a previous study, it was decided to test the influence of inbreeding and other parameters on fertility in this breed. Methods The study was based on all Irish Wolfhound litters registered in Sweden between 1976 and 2007 (n = 822 litters as provided by the Swedish Kennel Club (SKK and combined with a pedigree database going back to 1862. Analyses were performed using linear regression in a Generalised Linear Model and other tests in the SAS system®. Results Mean number of pups per litter was 6.01 ± 2.65, with a maximum of 13. There were no significant differences in either the number of litters or the number of pups between years of birth. Males were used for breeding at a significantly earlier age than females. Mean number of litters per parent was 2.96 ± 3.14 for males and 1.59 ± 0.87 for females. No influence of Wright's inbreeding coefficients over 5, 10, 20 and 30 generations and/or Meuwissen's inbreeding coefficients on litter size was detected. In the Generalised Linear Model, highly significant, but weak (coefficient of determination (R2 = 0.0341 influences were found for maternal age at mating as well as maternal inbreeding measured by Wright's inbreeding coefficient over 30 generations and Meuwissen's inbreeding coefficient. Paternal inbreeding coefficients over 5, 10, 20 and 30 generations and calculated after Meuwissen, as well as maternal inbreeding coefficients over 5, 10 and 20 generations did not have significant effects on litter size. Conclusion The low coefficient of determination (R2 value of the Generalised Linear Model indicates that inbreeding does not have a strong influence on fertility in Irish Wolfhounds, which is consistent with earlier results and the breed's genetic history. These results likely reflect the aforementioned genetic history and should not be extrapolated to other breeds without

Inbreeding coefficients and degree of consanguineous marriages in Spain: a review.

Science.gov (United States)

Fuster, Vicente; Colantonio, Sonia Edith

2003-01-01

The contribution of consanguineous marriages corresponding to uncle-niece or aunt-nephew (C12), first cousin (C22), first cousin once removed (C23), and second cousin (C33) to the inbreeding coefficient (alpha) was analyzed from a sample of Spanish areas and periods. Multiple regressions were performed taking as independent variables the different degrees of consanguinity previously selected (C12, C22, C23, and C33) and as dependent variable the inbreeding coefficient (alpha). According to the results obtained for any degree and period, rural frequencies always surpass urban. However, the pattern is similar in both areas. In the period where consanguinity was more elevated (1890-1929) the C22/C33 ratio increased. Its variation is not due to C22 and C33 changes in the same way. In rural areas, this ratio surpasses the expected value by a factor of 2-3, but in urban areas it was 7-10 times larger, in some cases due to migration. While in rural Spain the C33 frequency was approximately 1.5 times C22, in cities C22 was 1.5 times C33. The best fit among the various types of consanguineous matings and alpha involves a lineal relationship. Regardless of the number of variables contributing significantly to alpha, C22 matings are always present. Moreover, their standardized (beta) coefficients are the highest. The above indicates that this consanguineous relationship conditions the inbreeding coefficient the most. In the period of greater consanguinity, close relationships, uncle-niece C12, and first cousin once removed (C23) make a significant contribution to alpha. In rural Spain second cousins (C33) always significantly determined alpha; however, in cities the inbreeding variation was mainly due to C12 and C23. Copyright 2003 Wiley-Liss, Inc.

Evaluation of Optimum Genetic Contribution Theory to Control Inbreeding While Maximizing Genetic Response

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S.-H. Oh

2012-03-01

Full Text Available Inbreeding is the mating of relatives that produce progeny having more homozygous alleles than non-inbred animals. Inbreeding increases numbers of recessive alleles, which is often associated with decreased performance known as inbreeding depression. The magnitude of inbreeding depression depends on the level of inbreeding in the animal. Level of inbreeding is expressed by the inbreeding coefficient. One breeding goal in livestock is uniform productivity while maintaining acceptable inbreeding levels, especially keeping inbreeding less than 20%. However, in closed herds without the introduction of new genetic sources high levels of inbreeding over time are unavoidable. One method that increases selection response and minimizes inbreeding is selection of individuals by weighting estimated breeding values with average relationships among individuals. Optimum genetic contribution theory (OGC uses relationships among individuals as weighting factors. The algorithm is as follows: i Identify the individual having the best EBV; ii Calculate average relationships ( r j ¯ between selected and candidates; iii Select the individual having the best EBV adjusted for average relationships using the weighting factor k, E B V * = E B V j ( 1 - k r j ¯ . iv Repeat process until the number of individuals selected equals number required. The objective of this study was to compare simulated results based on OGC selection under different conditions over 30 generations. Individuals (n = 110 were generated for the base population with pseudo random numbers of N~ (0, 3, ten were assumed male, and the remainder female. Each male was mated to ten females, and every female was assumed to have 5 progeny resulting in 500 individuals in the following generation. Results showed the OGC algorithm effectively controlled inbreeding and maintained consistent increases in selection response. Difference in breeding values between selection with OGC algorithm and by EBV only was 8

Possible negative effects of inbreeding on semen quality in Shetland pony stallions

NARCIS (Netherlands)

Eldik, van P.; Waaij, van der E.H.; Ducro, B.J.; Kooper, A.W.; Stout, T.A.E.; Colenbrander, B.

2006-01-01

Inbreeding is widely believed to negatively affect reproductive performance. Indeed, in some species, high levels of inbreeding are thought to be the major cause of poor semen quality. It is, however, not clear whether inbreeding affects fertility in horses. In this study, the relationship between

Inbreeding effects on in vitro embryo production traits in Guzerá cattle.

Science.gov (United States)

Perez, B C; Balieiro, J C C; Ventura, R V; Bruneli, F A T; Peixoto, M G C D

2017-11-01

Inbreeding has been associated with the impairment of reproductive performance in many cattle breeds. Although the usage of reproductive biotechnologies has been increasing in bovine populations, not much attention has been given to the impact of inbreeding over cow's performance on artificial reproduction. The objective of this study was to estimate the impact of inbreeding on in vitro embryo production in a Guzerá breed population. The inbreeding coefficient (F), calculated as half of the co-ancestry of the individual's parents, was used as an estimate of inbreeding. The inbreeding coefficients of the donor, sire (used on in vitro fertilization) and of the embryos were included, separately, in the proposed models either as classificatory or continuous variables (linear and quadratic effects). The percentage of non-inbred individuals (or embryos) and mean F of donors, embryos and sires were 29.38%; 35.76%; 42.86% and 1.98±2.68; 1.32±3.13; 2.08±2.79, respectively. Two different models were considered, one for oocyte production traits and other for embryo production traits. The increase of F of the donor significantly (P0.05) effects were observed for the sire (father of the embryos) inbreeding coefficient over the traits analysed. Embryo's F influenced (Ptechnology. High levels of inbreeding should be avoided when selecting Guzerá female donors and planning in vitro fertilization mating.

Single-locus complementary sex determination in the inbreeding wasp Euodynerus foraminatus Saussure (Hymenoptera: Vespidae).

Science.gov (United States)

Stahlhut, J K; Cowan, D P

2004-03-01

The Hymenoptera have arrhenotokous haplodiploidy in which males normally develop from unfertilized eggs and are haploid, while females develop from fertilized eggs and are diploid. Multiple sex determination systems are known to underlie haplodiploidy, and the best understood is single-locus complementary sex determination (sl-CSD) in which sex is determined at a single polymorphic locus. Individuals heterozygous at the sex locus develop as females; individuals that are hemizygous (haploid) or homozygous (diploid) at the sex locus develop as males. sl-CSD can be detected with inbreeding experiments that produce diploid males in predictable proportions as well as sex ratio shifts due to diploid male production. This sex determination system is considered incompatible with inbreeding because the ensuing increase in homozygosity increases the production of diploid males that are inviable or infertile, imposing a high cost on matings between close relatives. However, in the solitary hunting wasp Euodynerus foraminatus, a species suspected of having sl-CSD, inbreeding may be common due to a high incidence of sibling matings at natal nests. In laboratory crosses with E. foraminatus, we find that sex ratios and diploid male production (detected as microsatellite heterozygosity) are consistent with sl-CSD, but not with other sex determination systems. This is the first documented example of sl-CSD in a hymenopteran with an apparent natural history of inbreeding, and thus presents a paradox for our understanding of hymenopteran genetics.

Effects of inbreeding on potential and realized immune responses in Tenebrio molitor.

Science.gov (United States)

Rantala, Markus J; Viitaniemi, Heidi; Roff, Derek A

2011-06-01

Although numerous studies on vertebrates suggest that inbreeding reduces their resistance against parasites and pathogens, studies in insects have found contradictory evidence. In this study we tested the effect of 1 generation of brother-sister mating (inbreeding) on potential and realized immune responses and other life-history traits in Tenebrio molitor. We found that inbreeding reduced adult mass, pre-adult survival and increased development time, suggesting that inbreeding reduced the condition of the adults and thus potentially made them more susceptible to physiological stress. However, we found no significant effect of inbreeding on the potential immune response (encapsulation response), but inbreeding reduced the realized immune response (resistance against the entomopathogenic fungi, Beauveria bassiana). There was a significant family effect on encapsulation response, but no family effect on the resistance against the entomopathogenic fungi. Given that this latter trait showed significant inbreeding depression and that the sample size for the family-effect analysis was small it is likely that the lack of a significant family effect is due to reduced statistical power, rather than the lack of a heritable basis to the trait. Our study highlights the importance of using pathogens and parasites in immunoecological studies.

Presence of inbreeding during a selection experiment with Merino ...

African Journals Online (AJOL)

192 individual inbreeding coefficients on natural and artificial selection cannot be ruled out. The effect of inbreeding on production and reproduction traits in Merino sheep has been the subject of many studies and reviews (Morley, 1954; Doney,. 1957; Lax & Brown, 1967; Turner & Young, 1969; Dolling,. 1970' Lamberson ...

Influence of Maximum Inbreeding Avoidance under BLUP EBV Selection on Pinzgau Population Diversity

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Radovan Kasarda

2011-05-01

Full Text Available Evaluated was effect of mating (random vs. maximum avoidance of inbreeding under BLUP EBV selection strategy. Existing population structure was under Monte Carlo stochastic simulation analyzed from the point to minimize increase of inbreeding. Maximum avoidance of inbreeding under BLUP selection resulted into comparable increase of inbreeding then random mating in average of 10 generation development. After 10 generations of simulation of mating strategy was observed ΔF= 6,51 % (2 sires, 5,20 % (3 sires, 3,22 % (4 sires resp. 2,94 % (5 sires. With increased number of sires selected, decrease of inbreeding was observed. With use of 4, resp. 5 sires increase of inbreeding was comparable to random mating with phenotypic selection. For saving of genetic diversity and prevention of population loss is important to minimize increase of inbreeding in small populations. Classical approach was based on balancing ratio of sires and dams in mating program. Contrariwise in the most of commercial populations small number of sires was used with high mating ratio.

Short communication: Analysis of inbreeding of the South African ...

African Journals Online (AJOL)

In South Africa, the Dairy Swiss breed, which originated in Switzerland, consists of 27 breeders and 1135 breeding cows. Pedigree information on the breed was analysed to determine its effective population size (Ne) and rate of inbreeding. The rate of inbreeding was 0.08% per year and 0.38% per generation.

Estimation of Inbreeding Coefficient and Its Effects on Lamb Survival in Sheep

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mohammad almasi

2016-04-01

Full Text Available Introduction The mating of related individuals produces an inbred offspring and leads to an increased homozygosity in the progeny, genetic variance decrease within families and increase between families. The ration of homozygosity for individuals was calculated by inbreeding coefficient. Inbred individuals may carry two alleles at a locus that are replicated from one gene in the previous generations, called identical by descent. The inbreeding coefficient should be monitored in a breeding program, since it plays an important role at decreasing of homeostasis, performance, reproduction and viability. The trend of inbreeding is an indicator for determining of inbreeding level in the herd. Inbreeding affects both phenotypic means of traits and genetic variances within population, thus it is an important factor for delimitations of genetic progress in a population. Reports showed an inbreeding increase led to decrease of phenotypic value in some of the productive and reproductive traits. Materials and Methods In the current study, the pedigree data of 14030 and 6215 records of Baluchi and Iranblack lambs that collected from 1984 to 2011 at the Abbasabad Sheep Breeding Station in Mashhad, Iran, 3588 records of Makoei lambs that collected from 1994 to 2011 at the Makoei sheep breeding station and 6140, records of Zandi lambs that collected from 1991 to 2011 at the Khejir Sheep Breeding Station in Tehran, Iran were used to estimating the inbreeding coefficient and its effects on lamb survival in these breeds. Lamb survival trait was scored as 1 and 0 for lamb surviving and not surviving at weaning weight, respectively. Inbreeding coefficient was estimated by relationship matrix algorithm (A=TDT' methodology using the CFC software program. Effects of inbreeding coefficient on lamb survival were estimated by restricted maximum likelihood (REML method under 12 different animal models using ASReml 3.0 computer programme. Coefficient of inbreeding for each

Trait specific consequences of fast and slow inbreeding: lessonsfrom captive populations of Drosophila melanogaster

DEFF Research Database (Denmark)

Mikkelsen, Karina Aarup; Loeschcke, Volker; Kristensen, Torsten Nygaard

2010-01-01

or 2 generations. These inbred lines were contrasted to non-inbred control lines. We investigated the effect of inbreeding and inbreeding rate in traits associated with fitness including heat, cold and desiccation stress resistance, egg-to-adult viability, development time, productivity, metabolic rate......The increased homozygosity due to inbreeding leads to expression of deleterious recessive alleles, which may cause inbreeding depression in small populations. The severity of inbreeding depression has been suggested to depend on the rate of inbreeding, with slower inbreeding being more effective...... and heat stress conditions. Reduced viability and increased developmental time were observed at stressful temperatures and inbreeding depression was on average more severe at stressful compared to benign temperatures...

EFFECT OF INBREEDING ON PRE-WEANING GROWTH TRAITS IN THALLI SHEEP

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A. HUSSAIN, P. AKHTAR, S. ALI, M. YOUNAS1 AND M. SHAFIQ2

2006-07-01

Full Text Available Pedigree records of 17250 Thalli sheep with 17030 lambings maintained at the Livestock Experiment Station, Rakh Ghulaman, Distt. Bhakkar, Pakistan during the period from 1975 to 2004 were utilized in the present study. Average values for birth weight, weights at 60 and 90 days of age, weaning weight and pre-weaning average daily gain were 4.11 ± 0.82, 11.58 ± 3.57, 14.92 ± 4.56, 18.95 ± 4.56 and 0.12 ± 0.04 kg, respectively. Coefficients of inbreeding ranged from 10.15 to 37.50 percent for 295 animals, being 1.70 percent of the flock. Inbreeding significantly (P<0.01 affected birth and 60 days weight. Birth weight and 60 days weight decreased by 0.051 and 0.048 kg for each 1 percent increase in the level of inbreeding. However, inbreeding had non significant effect on weight at 90 days of age, weaning weight and pre-weaning average daily gain. The regression values for these traits were 0.010, 0.083 and 0.105, respectively. It was concluded that inbreeding showed deleterious effects only in early stages of life but as the lambs grew older the effect of inbreeding on pre-weaning traits diminished.

Proteomic Characterization of Inbreeding-Related Cold Sensitivity in Drosophila melanogaster

DEFF Research Database (Denmark)

Vermeulen, C.J.; Pedersen, Kamilla Sofie; Beck, Hans C.

2013-01-01

insight into the molecular interplay between intrinsic stress responses, inbreeding depression and temperature tolerance, we performed a proteomic characterization of a well-defined conditional inbreeding effect in a single line of Drosophila melanogaster, which suffers from extreme cold sensitivity...

Evaluation of 99 S/sub 1/ lines of maize for inbreeding depression

International Nuclear Information System (INIS)

Ahmad, M.; Khan, S.; Ahmad, F.; Shah, N.H.; Akhtar, N.

2010-01-01

The research was conducted to evaluate the performance of S1 lines for inbreeding depression regarding different parameters, using maize variety Azam. The maize variety was self-pollinated for one generation in spring season and in the next sowing season 99 S1 lines obtained from selfing was sown with a parental line. Days to silking, pollen-shedding, plant height , ear-height, ear-length, ear-diameter, number of ears/row, kernel rows/ear and 100 kernel weight showed inbreeding depression with varying degrees while yield kg/ha showed severe inbreeding depression with an average of 362.08 kg/ha. Average value of inbreeding depression for days to silking and pollen-shedding was calculated as 2.02 and 2.21 days, respectively. Average values of inbreeding depression for plant height and ear-height were recorded as 21.50 cm and 4.87 cm, respectively. While, for earlength, ear-diameter, number of ears/row, kernel rows/ear and 100 grain weight, the average value of inbreeding depression was recorded as 1.80 cm, 0.2 cm, 2.5, 2.11 and 3.89 g, respectively. Grain yield was positively and significantly correlated with plant height, ear height and yield components. Maturity traits were positively and significantly linked with each other. It is concluded that by subjecting the maize to self-pollination nearly all the lines were affected; however, some lines were affected severely and others tolerated inbreeding to some extent. The lines showing tolerance against inbreeding depression was selected for further maize breeding. (author)

Employing optical code division multiple access technology in the all fiber loop vibration sensor system

Science.gov (United States)

Tseng, Shin-Pin; Yen, Chih-Ta; Syu, Rong-Shun; Cheng, Hsu-Chih

2013-12-01

This study proposes a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) framework to access the vibration frequency of a test object on the all fiber loop vibration sensor (AFLVS). Each user possesses an individual SAC, and fiber Bragg grating (FBG) encoders/decoders using multiple FBG arrays were adopted, providing excellent orthogonal properties in the frequency domain. The system also mitigates multiple access interference (MAI) among users. When an optical fiber is bent to a point exceeding the critical radius, the fiber loop sensor becomes sensitive to external physical parameters (e.g., temperature, strain, and vibration). The AFLVS involves placing a fiber loop with a specific radius on a designed vibration platform.

Inbreeding avoidance in spiders: evidence for rescue effect in fecundity of female spiders with outbreeding opportunity

DEFF Research Database (Denmark)

Bilde, T.; Maklakov, A.A.; Schilling, Nadia

2007-01-01

avoidance can be because of low risk of inbreeding, variation in tolerance to inbreeding or high costs of outbreeding. We examined the relationship between inbreeding depression and inbreeding avoidance adaptations under two levels of inbreeding in the spider Oedothorax apicatus, asking whether preference...... for unrelated sperm via pre- and/or post-copulatory mechanisms could restore female fitness when inbreeding depression increases. Using inbred isofemale lines we provided female spiders with one or two male spiders of different relatedness in five combinations: one male sib; one male nonsib; two male sibs; two...

Assessment of inbreeding depression in Nellore cows (Bos indicus) through high-density SNP genotypes

Science.gov (United States)

Inbreeding has been incriminated as a cause of decrease in reproductive performance in cattle. This negative correlation is known as ‘inbreeding depression’, and evidence supporting this hypothesis was generated from association studies between reproductive traits and estimates of inbreeding coeffic...

Superposition of DC magnetic fields by cascading multiple magnets in magnetic loops

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Fei Sun

2015-09-01

Full Text Available A novel method that can effectively collect the DC magnetic field produced by multiple separated magnets is proposed. With the proposed idea of a magnetic loop, the DC magnetic field produced by these separated magnets can be effectively superimposed together. The separated magnets can be cascaded in series or in parallel. A novel nested magnetic loop is also proposed to achieve a higher DC magnetic field in the common air region without increasing the DC magnetic field in each magnetic loop. The magnetic loop can be made by a magnetic hose, which is designed by transformation optics and can be realized by the combination of super-conductors and ferromagnetic materials.

Interactive effects of environmental stress and inbreeding on reproductive traits in a wild bird population.

Science.gov (United States)

Marr, A B; Arcese, P; Hochachka, W M; Reid, J M; Keller, L F

2006-11-01

1. Conservation biologists are concerned about the interactive effects of environmental stress and inbreeding because such interactions could affect the dynamics and extinction risk of small and isolated populations, but few studies have tested for these interactions in nature. 2. We used data from the long-term population study of song sparrows Melospiza melodia on Mandarte Island to examine the joint effects of inbreeding and environmental stress on four fitness traits that are known to be affected by the inbreeding level of adult birds: hatching success, laying date, male mating success and fledgling survival. 3. We found that inbreeding depression interacted with environmental stress to reduce hatching success in the nests of inbred females during periods of rain. 4. For laying date, we found equivocal support for an interaction between parental inbreeding and environmental stress. In this case, however, inbred females experienced less inbreeding depression in more stressful, cooler years. 5. For two other traits, we found no evidence that the strength of inbreeding depression varied with environmental stress. First, mated males fathered fewer nests per season if inbred or if the ratio of males to females in the population was high, but inbreeding depression did not depend on sex ratio. Second, fledglings survived poorly during rainy periods and if their father was inbred, but the effects of paternal inbreeding and rain did not interact. 6. Thus, even for a single species, interactions between the inbreeding level and environmental stress may not occur in all traits affected by inbreeding depression, and interactions that do occur will not always act synergistically to further decrease fitness.

Matrimonial distance, inbreeding coefficient and population size: Dhangar data.

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Majumder, P P; Malhotra, K C

1979-01-01

Data on the distance between the birthplaces of spouses (matrimonial distance) were collected from 2,260 married individuals belonging to 21 endogamous castes of the Dhangar (shepherd) cast-cluster of Maharashtra, India. The general form of the distribution of matrimonial distances is one which is extremely positively skewed and leptokurtic. The percentage of intra-village marriages generally decreases from the southern areas of Maharashtra to the northern areas of the state, as does the inbreeding coefficient. This situation is in conformity with the socio-cultural norms regulating matrimonial choice in south and north India. An attempt has been made to relate the degree of inbreeding to the mean matrimonial distance and population size. The mean matrimonial distance is more useful in predicting the degree of inbreeding than population size.

Assessment of inbreeding depression for functional herd life in the ...

African Journals Online (AJOL)

The objective of this study was to investigate the effect of inbreeding depression on functional herd life in the South African Jersey population based on individual level and rate of inbreeding. A pedigree file of the South African Jersey breed (n = 912 638) was obtained from the Integrated Registration and Genetic ...

Evidence of inbreeding depression on human height.

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Ruth McQuillan

Full Text Available Stature is a classical and highly heritable complex trait, with 80%-90% of variation explained by genetic factors. In recent years, genome-wide association studies (GWAS have successfully identified many common additive variants influencing human height; however, little attention has been given to the potential role of recessive genetic effects. Here, we investigated genome-wide recessive effects by an analysis of inbreeding depression on adult height in over 35,000 people from 21 different population samples. We found a highly significant inverse association between height and genome-wide homozygosity, equivalent to a height reduction of up to 3 cm in the offspring of first cousins compared with the offspring of unrelated individuals, an effect which remained after controlling for the effects of socio-economic status, an important confounder (χ(2 = 83.89, df = 1; p = 5.2 × 10(-20. There was, however, a high degree of heterogeneity among populations: whereas the direction of the effect was consistent across most population samples, the effect size differed significantly among populations. It is likely that this reflects true biological heterogeneity: whether or not an effect can be observed will depend on both the variance in homozygosity in the population and the chance inheritance of individual recessive genotypes. These results predict that multiple, rare, recessive variants influence human height. Although this exploratory work focuses on height alone, the methodology developed is generally applicable to heritable quantitative traits (QT, paving the way for an investigation into inbreeding effects, and therefore genetic architecture, on a range of QT of biomedical importance.

Heat Load Sharing in a Capillary Pumped Loop with Multiple Evaporators and Multiple Condensers

Science.gov (United States)

Ku, Jentung

2005-01-01

This paper describes the heat load sharing function among multiple parallel evaporators in a capillary pumped loop (CPL). In the normal mode of operation, the evaporators cool the instruments by absorbing the waste heat. When an instruments is turned off, the attached evaporator can keep it warm by receiving heat from other evaporators serving the operating instruments. This is referred to as heat load sharing. A theoretical basis of heat load sharing is given first. The fact that the wicks in the powered evaporators will develop capillary pressure to force the generated vapor to flow to cold locations where the pressure is lower leads to the conclusion that heat load sharing is an inherent function of a CPL with multiple evaporators. Heat load sharing has been verified with many CPLs in ground tests. Experimental results of the Capillary Pumped Loop 3 (CAPL 3) Flight Experiment are presented in this paper. Factors that affect the amount of heat being shared are discussed. Some constraints of heat load sharing are also addressed.

Better Fitness in Captive Cuvier's Gazelle despite Inbreeding Increase: Evidence of Purging?

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Eulalia Moreno

Full Text Available Captive breeding of endangered species often aims at preserving genetic diversity and to avoid the harmful effects of inbreeding. However, deleterious alleles causing inbreeding depression can be purged when inbreeding persists over several generations. Despite its great importance both for evolutionary biology and for captive breeding programmes, few studies have addressed whether and to which extent purging may occur. Here we undertake a longitudinal study with the largest captive population of Cuvier's gazelle managed under a European Endangered Species Programme since 1975. Previous results in this population have shown that highly inbred mothers tend to produce more daughters, and this fact was used in 2006 to reach a more appropriate sex-ratio in this polygynous species by changing the pairing strategy (i.e., pairing some inbred females instead of keeping them as surplus individuals in the population. Here, by using studbook data we explore whether purging has occurred in the population by investigating whether after the change in pairing strategy a inbreeding and homozygosity increased at the population level, b fitness (survival increased, and c the relationship between inbreeding and juvenile survival, was positive. Consistent with the existence of purging, we found an increase in inbreeding coefficients, homozygosity and juvenile survival. In addition, we showed that in the course of the breeding programme the relationship between inbreeding and juvenile survival was not uniform but rather changed over time: it was negative in the early years, flat in the middle years and positive after the change in pairing strategy. We highlight that by allowing inbred individuals to mate in captive stocks we may favour sex-ratio bias towards females, a desirable managing strategy to reduce the surplus of males that force most zoos to use ethical culling and euthanizing management tools. We discuss these possibilities but also acknowledge that many

Inbreeding depresses sperm competitiveness, but not fertilization or mating success in male Tribolium castaneum

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Michalczyk, Łukasz; Martin, Oliver Y.; Millard, Anna L.; Emerson, Brent C.; Gage, Matthew J. G.

2010-01-01

As populations decline to levels where reproduction among close genetic relatives becomes more probable, subsequent increases in homozygous recessive deleterious expression and/or loss of heterozygote advantage can lead to inbreeding depression. Here, we measure how inbreeding across replicate lines of the flour beetle Tribolium castaneum impacts on male reproductive fitness in the absence or presence of male–male competition. Effects on male evolution from mating pattern were removed by enforcing monogamous mating throughout. After inbreeding across eight generations, we found that male fertility in the absence of competition was unaffected. However, we found significant inbreeding depression of sperm competitiveness: non-inbred males won 57 per cent of fertilizations in competition, while inbred equivalents only sired 42 per cent. We also found that the P2 ‘offence’ role in sperm competition was significantly more depressed under inbreeding than sperm ‘defence’ (P1). Mating behaviour did not explain these differences, and there was no difference in the viability of offspring sired by inbred or non-inbred males. Sperm length variation was significantly greater in the ejaculates of inbred males. Our results show that male ability to achieve normal fertilization success was not depressed under strong inbreeding, but that inbreeding depression in these traits occurred when conditions of sperm competition were generated. PMID:20554548

Severe inbreeding depression in a wild wolf (Canis lupus) population.

Science.gov (United States)

Liberg, Olof; Andrén, Henrik; Pedersen, Hans-Christian; Sand, Håkan; Sejberg, Douglas; Wabakken, Petter; Kesson, Mikael; Bensch, Staffan

2005-03-22

The difficulty of obtaining pedigrees for wild populations has hampered the possibility of demonstrating inbreeding depression in nature. In a small, naturally restored, wild population of grey wolves in Scandinavia, founded in 1983, we constructed a pedigree for 24 of the 28 breeding pairs established in the period 1983-2002. Ancestry for the breeding animals was determined through a combination of field data (snow tracking and radio telemetry) and DNA microsatellite analysis. The population was founded by only three individuals. The inbreeding coefficient F varied between 0.00 and 0.41 for wolves born during the study period. The number of surviving pups per litter during their first winter after birth was strongly correlated with inbreeding coefficients of pups (R2=0.39, pwolf population.

Inbreeding depression in maize populations and its effects on the obtention of promising inbred lines

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Deoclecio Domingos Garbuglio

2017-10-01

Full Text Available Inbreeding can potentially be used for the development of inbred lines containing alleles of interest, but the genetic causes that control inbreeding depression are not completely known, and there are few studies found in the literature. The present study aimed to obtain estimates of inbreeding depression for eight traits in seven tropical maize populations, analyze the effects of inbreeding over generations and environments, and predict the behavior of inbred lines in future generation S? through linear regression methods. It was found that regardless of the base population used, prediction values could vary when the model was based on only 2 generations of inbreeding due to the environmental component. The influence of the environment in this type of study could be reduced when considering 3 generations of inbreeding, allowing greater precision in predicting the phenotypes of inbred lines. The use of linear regression was effective for inbred line prediction for the different agronomic traits evaluated. The use of 3 levels of inbreeding minimizes the effects of the environmental component in inbred line prediction for grain yield. GO-S was the most promising population for inbred line extraction.

Inbreeding depression of 28 maize elite open pollinated varieties

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Cleso Antônio Patto Pacheco

2002-01-01

Full Text Available The study of inbreeding depression is important for breeding strategies such as use of inbred progenies or extraction of inbreed lines. A diallel of 28 maize open-pollinated varieties was evaluated in 10 environments in the early 1990s. At the same time, S1 populations for each of the 28 varieties were evaluated in the same 10 experiments (environments. Yield reductions of the populations from S0 to S1 (mean of the 10 environments, varied from 34.6% (CMS-01 to 59.2% (CMS-30, with an average of 49.1%. Inbreeding depression was greater in populations with a wider genetic base, which had never been exposed to inbreeding (CMS-30, BR-107, PH4, Cunha, Saracura, Nitrodent, and Nitroflint. Inbred lines with greater yield means should be obtained from the BR-105, BR-111, CMS-01, CMS-03, BR-106, CMS-14c, and CMS-28 populations. The use of parameter estimates generated by analysis of inbreeding depression, allow to make inferences about frequencies of deleterious alleles in the population. The frequencies of favorable alleles in the parents can be obtained by diallel analysis. The association of these two types of information, can provide a better interpretation of the genetic parameters and also can improve the process of selection of parents for either an intra- or an inter-populational breeding program.

Effects of different levels of inbreeding on progeny fitness in Plantago coronopus

NARCIS (Netherlands)

Koelewijn, H.P.

1998-01-01

Inbreeding depression (delta) is a major selective force favoring outcrossing in flowering plants. Many phenotypic and genetic models of the evolution of selfing conclude that complete outcrossing should evolve whenever inbreeding depression is greater than one-half, otherwise selfing should evolve.

Effects of different levels of inbreeding on progeny fitness in Plantago coronopus

NARCIS (Netherlands)

Koelewijn, HP

Inbreeding depression (delta) is a major selective force favoring outcrossing in flowering plants. Many phenotypic and genetic models of the evolution of selfing conclude that complete outcrossing should evolve whenever inbreeding depression is greater than one-half, otherwise selfing should evolve.

Consequences of inbreeding and reduced genetic variation on tolerance to cadmium stress in the midge Chironomus riparius

International Nuclear Information System (INIS)

Nowak, Carsten; Jost, Daniel; Vogt, Christian; Oetken, Matthias; Schwenk, Klaus; Oehlmann, Joerg

2007-01-01

Inbreeding and loss of genetic variation are considered to be major threats to small and endangered populations. The reduction of fitness due to inbreeding is believed to be more severe under stressful environmental conditions. We generated nine strains of the ecotoxicological model organism Chironomus riparius of different inbreeding levels in order to test the hypothesis that the inbreeding level and thus the degree of genome-wide homozygosity influences the life-history under cadmium exposure. Therefore, midge populations were exposed to a gradient of sediment-bound cadmium. The level of genetic variation in the used strains was assessed using microsatellite markers. In the life-cycle tests, inbreeding reduced fitness within C. riparius populations both under control and stressed conditions. However, differences between genetically diverse and impoverished strains were greatest at high cadmium exposure. Overall, inbreeding effects were not only dependent on cadmium concentrations in the sediment, but also on the life-history trait investigated. While some parameters where only affected by inbreeding, others were altered by both, inbreeding and cadmium. For the larval developmental time, a significant interaction was found between inbreeding and cadmium stress. While all strains showed a similar developmental time under control conditions, high rates of inbreeding led to a significantly delayed emergence time under high cadmium concentrations, resulting in longer generation periods and reduced population growth rates as population-relevant effects. The results show, that bioassays with C. riparius are affected by the level of inbreeding within Chironomus test strains. Pollution stress is therefore likely to affect the survival of rare and endangered populations more severe than that of large and genetically diverse ones

Inbreeding depression in Solanum carolinense (Solanaceae, a species with a plastic self-incompatibility response

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Keser Lidewij H

2008-01-01

Full Text Available Abstract Background Solanum carolinense (horsenettle is a highly successful weed with a gametophytic self-incompatibility (SI system. Previous studies reveal that the strength of SI in S. carolinense is a plastic trait, associated with particular S-alleles. The importance of this variation in self-fertility on the ability of horsenettle to found and establish new populations will depend, to a large extent, on the magnitude of inbreeding depression. We performed a series of greenhouse and field experiments to determine the magnitude of inbreeding depression in S. carolinense, whether inbreeding depression varies by family, and whether the estimates of inbreeding depression vary under field and greenhouse conditions. We performed a series of controlled self- and cross-pollinations on 16 genets collected from a large population in Pennsylvania to obtain progeny with different levels of inbreeding. We grew the selfed and outcrossed progeny in the greenhouse and under field conditions and recorded various measures of growth and reproductive output. Results In the greenhouse study we found (1 a reduction in flower, fruit and seed production per fruit in inbred (selfed progeny when compared to outbred (outcrossed progeny; (2 a reduction in growth of resprouts obtained from rhizome cuttings of selfed progeny; and (3 an increase in the ability to self-fertilize in the selfed progeny. In the field, we found that (1 outcrossed progeny produced more leaves than their selfed siblings; (2 herbivory seems to add little to inbreeding depression; and (3 outcrossed plants grew faster and were able to set more fruits than selfed plants. Conclusion Solanum carolinense experiences low levels of inbreeding depression under greenhouse conditions and slightly more inbreeding depression under our field conditions. The combined effects of low levels of inbreeding depression and plasticity in the strength of SI suggest that the production of selfed progeny may play an

Inbreeding and oubreeding effects on pollen fitness and zygote survival in Silene nutans (Caryophyllaceae)

DEFF Research Database (Denmark)

Hauser, Thure Pavlo; Siegismund, H.R.

2000-01-01

inbreeding depression, oubreeding effects, outcrossing, pollen fitness, selfing, Silene nutans, zygote survival......inbreeding depression, oubreeding effects, outcrossing, pollen fitness, selfing, Silene nutans, zygote survival...

QTL mapping of inbreeding-related cold sensitivity and conditional lethality in Drosophila melanogaster

DEFF Research Database (Denmark)

Vermeulen, Corneel J.; Bijlsma, R.; Loeschcke, Volker

2008-01-01

of inbreeding-related and conditionally expressed lethality in Drosophila melanogaster. The lethal effect was triggered by exposure to a cold shock. We used a North Carolina crossing Design 3 to establish the mapping population, as well as to estimate the average dominance ratio and heritability. We found two......Inbreeding depression is a central theme within genetics, and is of specific interest for researchers within evolutionary and conservation genetics and animal and plant breeding. Inbreeding effects are thought to be caused by the joint expression of conditional and unconditional deleterious alleles....... Whenever the expression of deleterious alleles is conditional, this can result in extreme environmental sensitivity in certain inbred lineages. Analysis of conditional lethal effects can reveal some of the loci that are sensitive to inbreeding. We performed a QTL (quantitative trait locus) mapping study...

Mitigation of inbreeding while preserving genetic gain in genomic breeding programs for outbred plants.

Science.gov (United States)

Lin, Zibei; Shi, Fan; Hayes, Ben J; Daetwyler, Hans D

2017-05-01

Heuristic genomic inbreeding controls reduce inbreeding in genomic breeding schemes without reducing genetic gain. Genomic selection is increasingly being implemented in plant breeding programs to accelerate genetic gain of economically important traits. However, it may cause significant loss of genetic diversity when compared with traditional schemes using phenotypic selection. We propose heuristic strategies to control the rate of inbreeding in outbred plants, which can be categorised into three types: controls during mate allocation, during selection, and simultaneous selection and mate allocation. The proposed mate allocation measure GminF allocates two or more parents for mating in mating groups that minimise coancestry using a genomic relationship matrix. Two types of relationship-adjusted genomic breeding values for parent selection candidates ([Formula: see text]) and potential offspring ([Formula: see text]) are devised to control inbreeding during selection and even enabling simultaneous selection and mate allocation. These strategies were tested in a case study using a simulated perennial ryegrass breeding scheme. As compared to the genomic selection scheme without controls, all proposed strategies could significantly decrease inbreeding while achieving comparable genetic gain. In particular, the scenario using [Formula: see text] in simultaneous selection and mate allocation reduced inbreeding to one-third of the original genomic selection scheme. The proposed strategies are readily applicable in any outbred plant breeding program.

The effects of inbreeding on sperm quality traits in captive‐bred lake trout, Salvelinus namaycush (Walbaum, 1972)

DEFF Research Database (Denmark)

Johnson, K.; Butts, I. A. E.; Smith, J. L.

2015-01-01

The effects of inbreeding in both captive and wild‐caught species and populations have been reported to affect a wide variety of life history traits. Recently, the effects of inbreeding on reproductive traits such as sperm quality have become a subject of particular interest for conservation...... biology, evolutionary ecology, and management of captive populations. This study investigated the effects of inbreeding on sperm quality in a captive population of experimentally inbred and outbred lake trout, Salvelinus namaycush. It was found for moderately to highly inbred males (males with half......‐sib and full‐sib parents, respectively), that sperm quality traits (velocity, motility, linearity, longevity, spermatocrit and morphology) showed no apparent inbreeding depression. The apparent lack of inbreeding effects on sperm quality traits may be due to several factors including (i) no inbreeding...

Feral Pigeons (Columba livia Prefer Genetically Similar Mates despite Inbreeding Depression.

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Gwenaël Jacob

Full Text Available Avoidance of mating between related individuals is usually considered adaptive because it decreases the probability of inbreeding depression in offspring. However, mating between related partners can be adaptive if outbreeding depression is stronger than inbreeding depression or if females gain inclusive fitness benefits by mating with close kin. In the present study, we used microsatellite data to infer the parentage of juveniles born in a French colony of feral pigeons, which allowed us to deduce parent pairs. Despite detectable inbreeding depression, we found that pairwise relatedness between mates was significantly higher than between nonmates, with a mean coefficient of relatedness between mates of 0.065, approximately half the theoretical value for first cousins. This higher relatedness between mates cannot be explained by spatial genetic structure in this colonial bird; it therefore probably results from an active choice. As inbreeding but not outbreeding depression is observed in the study population, this finding accords with the idea that mating with genetically similar mates can confer a benefit in terms of inclusive fitness. Our results and published evidence suggest that preference for related individuals as mates might be relatively frequent in birds.

Simulations of plasma heating caused by the coalescence of multiple current loops in a proton-boron fusion plasma

International Nuclear Information System (INIS)

Haruki, T.; Yousefi, H. R.; Sakai, J.-I.

2010-01-01

Two dimensional particle-in-cell simulations of a dense plasma focus were performed to investigate a plasma heating process caused by the coalescence of multiple current loops in a proton-boron-electron plasma. Recently, it was reported that the electric field produced during the coalescence of two current loops in a proton-boron-electron plasma heats up all plasma species; proton-boron nuclear fusion may therefore be achievable using a dense plasma focus device. Based on this work, the coalescence process for four and eight current loops was investigated. It was found that the return current plays an important role in both the current pinch and the plasma heating. The coalescence of four current loops led to the breakup of the return current from the pinched plasma, resulting in plasma heating. For the coalescence of eight current loops, the plasma was confined by the pinch but the plasma heating was smaller than the two and four loop cases. Therefore the heating associated with current loop coalescence depends on the number of initial current loops. These results are useful for understanding the coalescence of multiple current loops in a proton-boron-electron plasma.

Control Strategies for Islanded Microgrid using Enhanced Hierarchical Control Structure with Multiple Current-Loop Damping Schemes

DEFF Research Database (Denmark)

Han, Yang; Shen, Pan; Zhao, Xin

2017-01-01

In this paper, the modeling, controller design, and stability analysis of the islanded microgrid (MG) using enhanced hierarchical control structure with multiple current loop damping schemes is proposed. The islanded MG is consisted of the parallel-connected voltage source inverters using LCL...... output filters, and the proposed control structure includes: the primary control with additional phase-shift loop, the secondary control for voltage amplitude and frequency restoration, the virtual impedance loops which contains virtual positive- and negative-sequence impedance loops at fundamental...... frequency, and virtual variable harmonic impedance loop at harmonic frequencies, and the inner voltage and current loop controllers. A small-signal model for the primary and secondary controls with additional phase-shift loop is presented, which shows an over-damped feature from eigenvalue analysis...

Telomere length reveals cumulative individual and transgenerational inbreeding effects in a passerine bird

NARCIS (Netherlands)

Bebbington, Kat; Spurgin, Lewis G.; Fairfield, Eleanor A.; Dugdale, Hannah L.; Komdeur, Jan; Burke, Terry; Richardson, David S.

Inbreeding results in more homozygous offspring that should suffer reduced fitness, but it can be difficult to quantify these costs for several reasons. First, inbreeding depression may vary with ecological or physiological stress and only be detectable over long time periods. Second, parental

Natal dispersal patterns are not associated with inbreeding avoidance in the Seychelles Warbler

NARCIS (Netherlands)

Eikenaar, C.; Komdeur, J.; Richardson, D. S.

In this study, we test whether patterns of territory inheritance, social mate choice and female-biased natal dispersal act as inbreeding avoidance mechanisms in the cooperatively breeding Seychelles warbler. Our results show that Seychelles warblers do not reduce the likelihood of inbreeding by

Estimating the inbreeding depression on cognitive behavior: a population based study of child cohort.

Directory of Open Access Journals (Sweden)

Mohd Fareed

Full Text Available Cognitive ability tests are widely assumed to measure maximal intellectual performance and predictive associations between intelligence quotient (IQ scores and later mental health problems. Very few epidemiologic studies have been done to demonstrate the relationship between familial inbreeding and modest cognitive impairments in children.We aimed to estimate the effect of inbreeding on children's cognitive behavior in comparison with non-inbred children.A cohort of 408 children (6 to 15 years of age was selected from inbred and non-inbred families of five Muslim populations of Jammu region. The Wechsler Intelligence Scales for Children (WISC was used to measure the verbal IQ (VIQ, performance IQ (PIQ and full scale IQ (FSIQ. Family pedigrees were drawn to access the family history and children's inbred status in terms of coefficient of inbreeding (F.We found significant decline in child cognitive abilities due to inbreeding and high frequency of mental retardation among offspring from inbred families. The mean differences (95% C.I. were reported for the VIQ, being -22.00 (-24.82, -19.17, PIQ -26.92 (-29.96, -23.87 and FSIQ -24.47 (-27.35,-21.59 for inbred as compared to non-inbred children (p<0.001 [corrected].The higher risk of being mentally retarded was found to be more obvious among inbred categories corresponding to the degree of inbreeding and the same accounts least for non-inbred children (p<0.0001. We observed an increase in the difference in mean values for VIQ, PIQ and FSIQ with the increase of inbreeding coefficient and these were found to be statistically significant (p<0.05. The regression analysis showed a fitness decline (depression for VIQ (R2 = 0.436, PIQ (R2 = 0.468 and FSIQ (R2 = 0.464 with increasing inbreeding coefficients (p<0.01.Our comprehensive assessment provides the evidence for inbreeding depression on cognitive abilities among children.

Allometric and non-allometric consequences of inbreeding on Drosophila melanogaster wings

DEFF Research Database (Denmark)

Trotta, Vincenzo; Cavicchi, Sandro; Guerra, Daniela

2011-01-01

Inbreeding is expected to increase the variability in size and shape within populations. The distinct effects of inbreeding on size and shape suggest that they are governed by different developmental pathways. One unresolved question is whether the non-allometric shape component is partially unco...

ARTICLE - Inbreeding depression in castor bean (Ricinus communis L. progenies

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Milton Krieger

2012-12-01

Full Text Available The purpose of this study was to investigate inbreeding depression (DE in castor bean. From a population derived from the Guarani cultivar, 60 mother plants were sampled. Three types of progenies were obtained from each one: from self-pollination (AU, from crosses (CR and from open pollination (PL. Grain yield of the progenies was evaluated in two locations. There was a strong interaction of progenies x locations, which led to obtaining estimates within each location. Broad variation was observed in inbreeding depression, with mean values of 6.7% and 13.4%, comparing AU progenies with PL progenies. It was observed that the population has high potential for selecting promising inbred lines. The frequency of mother plants generating progenies with simultaneous high general combination capacity and low inbreeding depression was low. Recurrent selection will increase the occurrence of parent plants associating these two properties, which is necessary for obtaining superior synthetic varieties.

The Self-Regulation Effect of Fertility Status on Inbreeding Aversion: When Fertile, Disgust Increases more in Response to Descriptions of One's Own than of Others' Inbreeding

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Jan Antfolk

2014-07-01

Full Text Available The ovulatory shift modulates emotions related to female sexuality. Because fertility status only affects the individual's own opportunity cost, the adaptive value of this shift is expected to stem from self-regulation. To test this assumption we asked women to contemplate various inbreeding descriptions: 1 they themselves having sex with male relatives; 2 their sister having sex with their common male relatives; and 3 an unrelated woman having sex with her male relatives (in 1, but not 2 and 3, negative fitness consequences are affected by the participant's fertility. We dichotomized the dependent variable disgust (ceiling vs. non-ceiling and analyzed the interaction between fertility status and description type. The ovulatory shift was stronger in descriptions where they themselves were described as engaging in inbreeding. A smaller increase was also found in reactions to others engaging in inbreeding. We explain the latter effect as due to self-reflection.

The effect of fast created inbreeding on litter size and body weights in mice

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Meuwissen Theo

2005-09-01

Full Text Available Abstract This study was designed to reveal any differences in effects of fast created versus total inbreeding on reproduction and body weights in mice. A line selected for large litter size for 124 generations (H and a control line (K maintained without selection for the same number of generations were crossed (HK and used as a basis for the experiment. Within the HK cross, full sib, cousin or random mating were practised for two generations in order to create new inbreeding (IBF at a fast rate. In the first generation of systematic mating, old inbreeding was regenerated in addition to creation of new inbreeding from the mating design giving total inbreeding (IBT. The number of pups born alive (NBA and body weights of the animals were then analysed by a model including both IBT and IBF. The IBT of the dam was in the present study found to reduce the mean NBA with -0.48 (± 0.22 (p F was -0.42 (± 0.27. For the trait NBA per female mated, the effect of IBT was estimated to be -0.45 (± 0.29 per 10% increase in the inbreeding coefficient and the effect of IBF was -0.90 (± 0.37 (p F of the dam could be found on sex-ratio and body weights at three and six weeks of age in a population already adjusted for IBT.

Investigating Inbreeding Depression for Heat Stress Tolerance in the Model Organism "Drosophila Melanogaster"

Science.gov (United States)

Pedersen, Kamilla Sofie; Pedersen, Louise Dybdahl; Sorensen, Anders Christian; Nielsen, Anna Busch; Kristensen, Torsten Nygaard

2012-01-01

Mating between closely related individuals often causes reduced fitness, which is termed "inbreeding depression". Inbreeding is, therefore, a threat towards the persistence of animal and plant populations. Here we present methods and results from a practical for high-school and first-year university students and discuss learning outcomes…

Inbreeding depression in selfs of redwood

Science.gov (United States)

W. J. Libby; B. G. McCutchan; C. I. Millar

1981-01-01

Given the polyploid chromosome constitution of Sequoia sempervirens, there was reason to question whether it would exhibit inbreeding depression. Preliminary results from studies of self and related outcross families are reported as a guide to the selection of trees for redwood seed orchards and breeding-orchards. The data indicate that, compared to...

The association of genotype-based inbreeding coefficient with a range of physical and psychological human traits.

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Karin J H Verweij

Full Text Available Across animal species, offspring of closely related mates exhibit lower fitness, a phenomenon called inbreeding depression. Inbreeding depression in humans is less well understood because mating between close relatives is generally rare and stigmatised, confounding investigation of its effect on fitness-relevant traits. Recently, the availability of high-density genotype data has enabled quantification of variation in distant inbreeding in 'outbred' human populations, but the low variance of inbreeding detected from genetic data in most outbred populations means large samples are required to test effects, and only a few traits have yet been studied. However, it is likely that isolated populations, or those with a small effective population size, have higher variation in inbreeding and therefore require smaller sample sizes to detect inbreeding effects. With a small effective population size and low immigration, Northern Finland is such a population. We make use of a sample of ∼5,500 'unrelated' individuals in the Northern Finnish Birth Cohort 1966 with known genotypes and measured phenotypes across a range of fitness-relevant physical and psychological traits, including birth length and adult height, body mass index (BMI, waist-to-hip ratio, blood pressure, heart rate, grip strength, educational attainment, income, marital status, handedness, health, and schizotypal features. We find significant associations in the predicted direction between individuals' inbreeding coefficient (measured by proportion of the genome in runs of homozygosity and eight of the 18 traits investigated, significantly more than the one or two expected by chance. These results are consistent with inbreeding depression effects on a range of human traits, but further research is needed to replicate and test alternative explanations for these effects.

Inbreeding depression in an insect with maternal care: influences of family interactions, life stage and offspring sex.

Science.gov (United States)

Meunier, J; Kölliker, M

2013-10-01

Although inbreeding is commonly known to depress individual fitness, the severity of inbreeding depression varies considerably across species. Among the factors contributing to this variation, family interactions, life stage and sex of offspring have been proposed, but their joint influence on inbreeding depression remains poorly understood. Here, we demonstrate that these three factors jointly shape inbreeding depression in the European earwig, Forficula auricularia. Using a series of cross-breeding, split-clutch and brood size manipulation experiments conducted over two generations, we first showed that sib mating (leading to inbred offspring) did not influence the reproductive success of earwig parents. Second, the presence of tending mothers and the strength of sibling competition (i.e. brood size) did not influence the expression of inbreeding depression in the inbred offspring. By contrast, our results revealed that inbreeding dramatically depressed the reproductive success of inbred adult male offspring, but only had little effect on the reproductive success of inbred adult female offspring. Overall, this study demonstrates limited effects of family interactions on inbreeding depression in this species and emphasizes the importance of disentangling effects of sib mating early and late during development to better understand the evolution of mating systems and population dynamics. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Intergenerational effects of inbreeding in Nicrophorus vespilloides: offspring suffer fitness costs when either they or their parents are inbred.

Science.gov (United States)

Mattey, S N; Strutt, L; Smiseth, P T

2013-04-01

Inbreeding depression is the reduction in fitness caused by mating between related individuals. Inbreeding is expected to cause a reduction in offspring fitness when the offspring themselves are inbred, but outbred individuals may also suffer a reduction in fitness when they depend on care from inbred parents. At present, little is known about the significance of such intergenerational effects of inbreeding. Here, we report two experiments on the burying beetle Nicrophorus vespilloides, an insect with elaborate parental care, in which we investigated inbreeding depression in offspring when either the offspring themselves or their parents were inbred. We found substantial inbreeding depression when offspring were inbred, including reductions in hatching success of inbred eggs and survival of inbred offspring. We also found substantial inbreeding depression when parents were inbred, including reductions in hatching success of eggs produced by inbred parents and survival of outbred offspring that received care from inbred parents. Our results suggest that intergenerational effects of inbreeding can have substantial fitness costs to offspring, and that future studies need to incorporate such costs to obtain accurate estimates of inbreeding depression. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

Founder-specific inbreeding depression affects racing performance in Thoroughbred horses.

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Todd, Evelyn T; Ho, Simon Y W; Thomson, Peter C; Ang, Rachel A; Velie, Brandon D; Hamilton, Natasha A

2018-04-18

The Thoroughbred horse has played an important role in both sporting and economic aspects of society since the establishment of the breed in the 1700s. The extensive pedigree and phenotypic information available for the Thoroughbred horse population provides a unique opportunity to examine the effects of 300 years of selective breeding on genetic load. By analysing the relationship between inbreeding and racing performance of 135,572 individuals, we found that selective breeding has not efficiently alleviated the Australian Thoroughbred population of its genetic load. However, we found evidence for purging in the population that might have improved racing performance over time. Over 80% of inbreeding in the contemporary population is accounted for by a small number of ancestors from the foundation of the breed. Inbreeding to these ancestors has variable effects on fitness, demonstrating that an understanding of the distribution of genetic load is important in improving the phenotypic value of a population in the future. Our findings hold value not only for Thoroughbred and other domestic breeds, but also for small and endangered populations where such comprehensive information is not available.

Towards a complete North American Anabaptist Genealogy II: analysis of inbreeding.

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Agarwala, R; Schäffer, A A; Tomlin, J F

2001-08-01

We describe a large genealogy data base, which can be searched by computer, of 295,095 Amish and Mennonite individuals. The data base was constructed by merging our existing Anabaptist Genealogy Database 2.0 containing approximately 85,000 individuals with a genealogy file containing approximately 242,000 individuals, kindly provided by Mr. James Hostetler. The merging process corrected thousands of inconsistencies and eliminated hundreds of duplicate individuals. Geneticists have long been interested in Anabaptist populations because they are closed and have detailed written genealogies. The creation of an enlarged and unified data base affords the opportunity to examine inbreeding trends and correlates in these populations. We show the following results. The frequency of consanguineous marriages shows steady increase over time and reached approximately 85% for individuals born in 1940-1959. Among consanguineous marriages, the median kinship coefficient stayed stable in the 19th century, but rose from 0.0115 to 0.0151 in the 20th century. There are statistically significant associations (p < 0.0001) between inbreeding and family size and interbirth intervals in the 20th century. There is an association (p < 0.0005) between inbreeding and early death for individuals born in 1920-1959. However, this association reverses dramatically (p < 0.0005 in the opposite direction) for individuals born in 1960-1979. We tested for an association between inbreeding and being the mother of twins, but found none.

Inter-specific competitive stress does not affect the magnitude of inbreeding depression

OpenAIRE

Willi, Yvonne; Dietrich, Stefan; van Kleunen, Mark; Fischer, Markus

2007-01-01

Hypothesis: Stressful inter-specific competition enhances inbreeding depression.Organisms: Creeping spearwort (Ranunculus reptans L.) and its common competitor, thecreeping bentgrass (Agrostis stolonifera L.).Field site: Outdoor common garden experiment at the University of Potsdam.Methods: We collected plants of 12 natural populations of R. reptans differing in mean parental inbreeding coefficient (0.01–0.26). We performed within-population crosses for twogenerations and kept the offspring i...

Lack of nucleotide variability in a beetle pest with extreme inbreeding.

Science.gov (United States)

Andreev, D; Breilid, H; Kirkendall, L; Brun, L O; ffrench-Constant, R H

1998-05-01

The coffee berry borer beetle Hypothenemus hampei (Ferrari) (Curculionidae: Scolytinae) is the major insect pest of coffee and has spread to most of the coffee-growing countries of the world. This beetle also displays an unusual life cycle, with regular sibling mating. This regular inbreeding and the population bottlenecks occurring on colonization of new regions should lead to low levels of genetic diversity. We were therefore interested in determining the level of nucleotide variation in nuclear and mitochondrial genomes of this beetle worldwide. Here we show that two nuclear loci (Resistance to dieldrin and ITS2) are completely invariant, whereas some variability is maintained at a mitochondrial locus (COI), probably corresponding to a higher mutation rate in the mitochondrial genome. Phylogenetic analysis of the mitochondrial data shows only two clades of beetle haplotypes outside of Kenya, the proposed origin of the species. These data confirm that inbreeding greatly reduces nucleotide variation and suggest the recent global spread of only two inbreeding lines of this bark beetle.

How Much Does Inbreeding Reduce Heterozygosity? Empirical Results from Aedes aegypti

Science.gov (United States)

Powell, Jeffrey R.; Evans, Benjamin R.

2017-01-01

Deriving strains of mosquitoes with reduced genetic variation is useful, if not necessary, for many genetic studies. Inbreeding is the standard way of achieving this. Full-sib inbreeding the mosquito Aedes aegypti for seven generations reduced heterozygosity to 72% of the initial heterozygosity in contrast to the expected 13%. This deviation from expectations is likely due to high frequencies of deleterious recessive alleles that, given the number of markers studied (27,674 single nucleotide polymorphisms [SNPs]), must be quite densely spread in the genome. PMID:27799643

Investigating inbreeding depression for heat stress tolerance in the model organism Drosophila melanogaster

DEFF Research Database (Denmark)

Pedersen, Kamilla Sofie; Pedersen, Louise Dybdahl; Sørensen, Anders Christian

2012-01-01

Mating between closely related individuals often causes reduced fitness, which is termed ‘inbreeding depression’. Inbreeding is, therefore, a threat towards the persistence of animal and plant populations. Here we present methods and results from a practical for high-school and first-year univers......Mating between closely related individuals often causes reduced fitness, which is termed ‘inbreeding depression’. Inbreeding is, therefore, a threat towards the persistence of animal and plant populations. Here we present methods and results from a practical for high-school and first......-year university students and discuss learning outcomes of the exercise as an example of inquiry-based science teaching. We use the model organism Drosophila melanogaster to test the ability of inbred and control (non-inbred) females to survive heat stress exposure. Flies were anaesthetised and collected...... into vials before exposure to 38°C heat stress in a water bath for 1 h. Half an hour later the number of comatose inbred and control flies were scored and chi-square statistic procedures were used to test for different degrees of heat stress tolerance between the two lines of flies. The practical introduces...

An inbreeding model of associative overdominance during a population bottleneck.

Science.gov (United States)

Bierne, N; Tsitrone, A; David, P

2000-08-01

Associative overdominance, the fitness difference between heterozygotes and homozygotes at a neutral locus, is classically described using two categories of models: linkage disequilibrium in small populations or identity disequilibrium in infinite, partially selfing populations. In both cases, only equilibrium situations have been considered. In the present study, associative overdominance is related to the distribution of individual inbreeding levels (i.e., genomic autozygosity). Our model integrates the effects of physical linkage and variation in inbreeding history among individual pedigrees. Hence, linkage and identity disequilibrium, traditionally presented as alternatives, are summarized within a single framework. This allows studying nonequilibrium situations in which both occur simultaneously. The model is applied to the case of an infinite population undergoing a sustained population bottleneck. The effects of bottleneck size, mating system, marker gene diversity, deleterious genomic mutation parameters, and physical linkage are evaluated. Bottlenecks transiently generate much larger associative overdominance than observed in equilibrium finite populations and represent a plausible explanation of empirical results obtained, for instance, in marine species. Moreover, the main origin of associative overdominance is random variation in individual inbreeding whereas physical linkage has little effect.

Predicting rates of inbreeding in populations undergoing selection

NARCIS (Netherlands)

Woolliams, J.A.; Bijma, P.

2000-01-01

Tractable forms of predicting rates of inbreeding (F) in selected populations with general indices, nonrandom mating, and overlapping generations were developed, with the principal results assuming a period of equilibrium in the selection process. An existing theorem concerning the relationship

Academic Inbreeding: Exploring Its Characteristics and Rationale in Japanese Universities Using a Qualitative Perspective

Science.gov (United States)

Horta, Hugo; Sato, Machi; Yonezawa, Akiyoshi

2011-01-01

This study analyses why and how academic inbreeding as a recruitment practice continues to prevail in Japan, a country with a mature higher education system, where high rates of academic inbreeding endure in most of the research-oriented universities in spite of several higher education reforms. Based on a qualitative analysis, we disclose three…

Aesthetic rehabilitation with multiple loop connectors

Directory of Open Access Journals (Sweden)

Ashish Kalra

2013-01-01

Full Text Available Patients with a missing tooth along with diastema have limited treatment options to restore the edentulous space. The use of a conventional fixed partial denture (FPD to replace the missing tooth may result in too wide anterior teeth leading to poor esthetics. The diastema resulting from the missing central incisors can be managed with implant-supported prosthesis or FPD with loop connectors. An old lady reported with chief complaints of missing upper anterior teeth due to trauma. Her past dental history revealed that she was having generalized spacing between her upper anterior teeth. Considering her esthetic requirement of maintaining the diastema between 12, 11, 22, and 21, the treatment option of 06 units porcelain fused to metal FPD from canine to canine with intermittent loop connectors between 21, 22, 11, 12 was planned. Connectors basically link different parts of FPDs. The modified FPD with loop connectors enhanced the natural appearance of the restoration, maintained the diastemas and the proper emergence profile, and preserve the remaining tooth structure of abutment teeth. This clinical report discussed a method for fabrication of a modified FPD with loop connectors to restore the wide span created by missing central incisors.

Metabolomic Signatures of Inbreeding at Benign and Stressful Temperatures in Drosophila melanogaster

DEFF Research Database (Denmark)

Pedersen, Kamilla Sofie; Kristensen, Torsten Nygård; Loeschcke, Volker

2008-01-01

-line variation in metabolite profiles compared to outbred lines. In contrast to previous observations revealing interactions between inbreeding and environmental stress on gene expression patterns and life-history traits, the effect of inbreeding on the metabolite profile was similar across the different...... and five inbred lines were studied by nuclear magnetic resonance spectroscopy after exposure to benign temperature, heat stress, or cold stress. In both the absence and the presence of temperature stress, metabolite levels were significantly different among inbred and outbred lines. The major effect...

Short communication: Effective population size and inbreeding rate ...

African Journals Online (AJOL)

Short communication: Effective population size and inbreeding rate of indigenous Nguni cattle under in situ conservation in the low-input communal production ... as not at risk of extinction, while the individual enterprises were classified as being endangered-maintained without the exchange of germ plasm among them.

Inbreeding avoidance influences the viability of reintroduced populations of African wild dogs (Lycaon pictus.

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Penny A Becker

Full Text Available The conservation of many fragmented and small populations of endangered African wild dogs (Lycaon pictus relies on understanding the natural processes affecting genetic diversity, demographics, and future viability. We used extensive behavioural, life-history, and genetic data from reintroduced African wild dogs in South Africa to (1 test for inbreeding avoidance via mate selection and (2 model the potential consequences of avoidance on population persistence. Results suggested that wild dogs avoided mating with kin. Inbreeding was rare in natal packs, after reproductive vacancies, and between sibling cohorts (observed on 0.8%, 12.5%, and 3.8% of occasions, respectively. Only one of the six (16.7% breeding pairs confirmed as third-order (or closer kin consisted of animals that were familiar with each other, while no other paired individuals had any prior association. Computer-simulated populations allowed to experience inbreeding had only a 1.6% probability of extinction within 100 years, whereas all populations avoiding incestuous matings became extinct due to the absence of unrelated mates. Populations that avoided mating with first-order relatives became extinct after 63 years compared with persistence of 37 and 19 years for those also prevented from second-order and third-order matings, respectively. Although stronger inbreeding avoidance maintains significantly more genetic variation, our results demonstrate the potentially severe demographic impacts of reduced numbers of suitable mates on the future viability of small, isolated wild dog populations. The rapid rate of population decline suggests that extinction may occur before inbreeding depression is observed.

An evaluation of multiple annealing and looping based genome amplification using a synthetic bacterial community

KAUST Repository

Wang, Yong; Gao, Zhaoming; Xu, Ying; Li, Guangyu; He, Lisheng; Qian, Peiyuan

2016-01-01

-generation-sequencing technology. Using a synthetic bacterial community, the amplification efficiency of the Multiple Annealing and Looping Based Amplification Cycles (MALBAC) kit that is originally developed to amplify the single-cell genomic DNA of mammalian organisms

Inbreeding avoidance, patch isolation and matrix permeability influence dispersal and settlement choices by male agile antechinus in a fragmented landscape.

Science.gov (United States)

Banks, Sam C; Lindenmayer, David B

2014-03-01

Animal dispersal is highly non-random and has important implications for the dynamics of populations in fragmented habitat. We identified interpatch dispersal events from genetic tagging, parentage analyses and assignment tests and modelled the factors associated with apparent emigration and post-dispersal settlement choices by individual male agile antechinus (Antechinus agilis, a marsupial carnivore of south-east Australian forests). Emigration decisions were best modelled with on data patch isolation and inbreeding risk. The choice of dispersal destination by males was influenced by inbreeding risk, female abundance, patch size, patch quality and matrix permeability (variation in land cover). Males were less likely to settle in patches without highly unrelated females. Our findings highlight the importance of individual-level dispersal data for understanding how multiple processes drive non-randomness in dispersal in modified landscapes. Fragmented landscapes present novel environmental, demographic and genetic contexts in which dispersal decisions are made, so the major factors affecting dispersal decisions in fragmented habitat may differ considerably from unfragmented landscapes. We show that the spatial scale of genetic neighbourhoods can be large in fragmented habitat, such that dispersing males can potentially settle in the presence of genetically similar females after moving considerable distances, thereby necessitating both a choice to emigrate and a choice of where to settle to avoid inbreeding. © 2013 The Authors. Journal of Animal Ecology © 2013 British Ecological Society.

A major QTL affects temperature sensitive adult lethality and inbreeding depression in life span in Drosophila melanogaster

NARCIS (Netherlands)

Vermeulen, Cornelius J.; Bijlsma, R.; Loeschcke, Volker

2008-01-01

Background: The study of inbreeding depression has major relevance for many disciplines, including conservation genetics and evolutionary biology. Still, the molecular genetic basis of this phenomenon remains poorly characterised, as knowledge on the mechanistic causes of inbreeding depression and

Inbreeding affects sexual signalling in males but not females of Tenebrio molitor.

Science.gov (United States)

Pölkki, Mari; Krams, Indrikis; Kangassalo, Katariina; Rantala, Markus J

2012-06-23

In many species of animals, individuals advertise their quality with sexual signals to obtain mates. Chemical signals such as volatile pheromones are species specific, and their primary purpose is to influence mate choice by carrying information about the phenotypic and genetic quality of the sender. The deleterious effects of consanguineous mating on individual quality are generally known, whereas the effect of inbreeding on sexual signalling is poorly understood. Here, we tested whether inbreeding reduces the attractiveness of sexual signalling in the mealworm beetle, Tenebrio molitor, by testing the preferences for odours of inbred and outbred (control) individuals of the opposite sex. Females were more attracted to the odours produced by outbred males than the odours produced by inbred males, suggesting that inbreeding reduces the attractiveness of male sexual signalling. However, we did not find any difference between the attractiveness of inbred and outbred female odours, which may indicate that the quality of females is either irrelevant for T. molitor males or quality is not revealed through female odours.

Early-acting inbreeding depression and reproductive success in the highbush blueberry, Vaccinium corymbosum L.

Science.gov (United States)

Krebs, S L; Hancock, J F

1990-06-01

Tetraploid Vaccinium corymbosum genotypes exhibit wide variability in seed set following self- and cross-pollinations. In this paper, a post-zygotic mechanism (seed abortion) under polygenic control is proposed as the basis for fertility differences in this species. A pollen chase experiment indicated that self-pollen tubes fertilize ovules, but are also 'outcompeted' by foreign male gametes in pollen mixtures. Matings among cultivars derived from a pedigree showed a linear decrease in seed number per fruit, and increase in seed abortion, with increasing relatedness among parents. Selfed (S1) progeny from self-fertile parents were largely self-sterile. At zygotic levels of inbreeding of F>0.3 there was little or no fertility, suggesting that an inbreeding threshold regulates reproductive success in V. corymbosum matings. Individuals below the threshold are facultative selfers, while those above it are obligate outcrossers. Inbreeding also caused a decrease in pollen viability, and reduced female fertility more rapidly than male fertility. These phenomena are discussed in terms of two models of genetic load: (1) mutational load - homozygosity for recessive embryolethal or sub-lethal mutations and (2) segregational load - loss of allelic interactions essential for embryonic vigor. Self-infertility in highbush blueberries is placed in the context of 'late-acting' self-incompatibility versus 'early-acting' inbreeding depression in angiosperms.

Cubic-spline interpolation to estimate effects of inbreeding on milk yield in first lactation Holstein cows

Directory of Open Access Journals (Sweden)

Makram J. Geha

2011-01-01

Full Text Available Milk yield records (305d, 2X, actual milk yield of 123,639 registered first lactation Holstein cows were used to compare linear regression (y = β0 + β1X + e ,quadratic regression, (y = β0 + β1X + β2X2 + e cubic regression (y = β0 + β1X + β2X2 + β3X3 + e and fixed factor models, with cubic-spline interpolation models, for estimating the effects of inbreeding on milk yield. Ten animal models, all with herd-year-season of calving as fixed effect, were compared using the Akaike corrected-Information Criterion (AICc. The cubic-spline interpolation model with seven knots had the lowest AICc, whereas for all those labeled as "traditional", AICc was higher than the best model. Results from fitting inbreeding using a cubic-spline with seven knots were compared to results from fitting inbreeding as a linear covariate or as a fixed factor with seven levels. Estimates of inbreeding effects were not significantly different between the cubic-spline model and the fixed factor model, but were significantly different from the linear regression model. Milk yield decreased significantly at inbreeding levels greater than 9%. Variance component estimates were similar for the three models. Ranking of the top 100 sires with daughter records remained unaffected by the model used.

Multiple Convergent Origins of Workerlessness and Inbreeding in the Socially Parasitic Ant Genus Myrmoxenus.

Science.gov (United States)

Heinze, Jürgen; Buschinger, Alfred; Poettinger, Theo; Suefuji, Masaki

2015-01-01

The socially parasitic ant genus Myrmoxenus varies strongly in fundamental life history traits, such as queen-worker ratio, the timing of sexual production, and mating behavior. Myrmoxenus queens generally take over nests of Temnothorax ants, kill the resident queen by throttling, and force the workers to take care of the social parasite's brood. Young queens of M. ravouxi and other species produce large numbers of workers, which during "slave-raids" pillage host pupae from neighboring Temnothorax colonies to increase the workforce in their own nests. Other species, such as M. corsicus, have lost caste polyphenism and rear only male and female sexual offspring. Using sequences of the genes CO I/CO II and wingless we reconstruct the phylogeny of Myrmoxenus and document that the worker caste was lost convergently at least three times. Furthermore, mating in the nest and inbreeding obviously also evolved in parallel from ancestors whose sexuals presumably mated during nuptial flights. Myrmoxenus might thus provide a suitable model to investigate caste differentiation and the plasticity of mating behavior in Hymenoptera.

Multiple Convergent Origins of Workerlessness and Inbreeding in the Socially Parasitic Ant Genus Myrmoxenus.

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Jürgen Heinze

Full Text Available The socially parasitic ant genus Myrmoxenus varies strongly in fundamental life history traits, such as queen-worker ratio, the timing of sexual production, and mating behavior. Myrmoxenus queens generally take over nests of Temnothorax ants, kill the resident queen by throttling, and force the workers to take care of the social parasite's brood. Young queens of M. ravouxi and other species produce large numbers of workers, which during "slave-raids" pillage host pupae from neighboring Temnothorax colonies to increase the workforce in their own nests. Other species, such as M. corsicus, have lost caste polyphenism and rear only male and female sexual offspring. Using sequences of the genes CO I/CO II and wingless we reconstruct the phylogeny of Myrmoxenus and document that the worker caste was lost convergently at least three times. Furthermore, mating in the nest and inbreeding obviously also evolved in parallel from ancestors whose sexuals presumably mated during nuptial flights. Myrmoxenus might thus provide a suitable model to investigate caste differentiation and the plasticity of mating behavior in Hymenoptera.

A major QTL affects temperature sensitive adult lethality and inbreeding depression in life span in Drosophila melanogaster.

DEFF Research Database (Denmark)

Vermeulen, Corneel J.; Bijlsma, R.; Loeschcke, Volker

2008-01-01

of inbreeding effects in specific traits, such as age-specific mortality and life span, provide a good starting point, as a limited set of genes is expected to be involved. Results Here we report on a QTL mapping study on inbreeding related and temperature sensitive lethality in male Drosophila melanogaster...... and the molecular properties of genes that give rise to or modulate its deleterious effects is lacking. These questions warrant the detailed study of genetic loci giving rise to inbreeding depression. However, the complex and polygenic nature of general inbreeding depression makes this a daunting task. Study...... simple, being due mainly to a single recessive QTL on the left arm of chromosome 2. This locus colocalised with a QTL that conditioned variation in female life span, acting as an overdominant locus for this trait. Male life span was additionally affected by variation at the X-chromosome. Conclusion...

Extreme temperatures increase the deleterious consequences of inbreeding under laboratory and semi-natural conditions

DEFF Research Database (Denmark)

Kristensen, Torsten Nygård; Barker, J. Stuart F.; Pedersen, Kamilla Sofie

2008-01-01

when compared with non-inbred lines of Drosophila melanogaster under different temperature conditions. Egg-to-adult viability, developmental time and sex ratio of emerging adults are studied under low, intermediate and high temperatures under laboratory as well as semi-natural conditions. The results...... show inbreeding depression for egg-to-adult viability. The level of inbreeding depression is highly dependent on test temperature and is observed only at low and high temperatures. Inbreeding did not affect the developmental time or the sex ratio of emerging adults. However, temperature affected...... the sex ratio with more females relative to males emerging at low temperatures, suggesting that selection against males in pre-adult life stages is stronger at low temperatures. The coefficient of variation (CV) of egg-to-adult viability within and among lines is higher for inbred flies and generally...

An effective rotational mating scheme for inbreeding reduction in captive populations illustrated by the rare sheep breed

NARCIS (Netherlands)

Windig, J.J.; Lansbergen, L.M.T.E.

2008-01-01

Within breeds and other captive populations, the risk of high inbreeding rates and loss of diversity can be high within (small) herds or subpopulations. When exchange of animals between different subpopulations is organised according to a rotational mating scheme, inbreeding rates can be restricted.

Effects of inbreeding and other systematic effects on fertility of Black Forest Draught horses in Germany.

Science.gov (United States)

Müller-Unterberg, Maarit; Wallmann, Sandra; Distl, Ottmar

2017-10-18

The Black Forest Draught horse (BFDH) is an endangered German coldblood breed with its origin in the area of the Black Forest in South Germany. In this retrospective study, the influence of the inbreeding coefficient on foaling rates was investigated using records from ten breeding seasons. Due to the small population size of BFDH, the level of inbreeding is increasing and may have an effect on foaling rates.The data of the present study included all coverings reported for 1024 BFDH mares in the years 2001-2009. These mares were covered by 32 BFDH stallions from the State Stud Marbach. Data from 4534 estrus cycles was used to calculate per cycle foaling rate (CFR). Pedigree data contained all studbook data up to the foundation of the breed as early as 1836. The level of inbreeding of the mare, stallion and expected foal along with other systematic effects on CFR were analysed using a generalized linear mixed model approach. Stallion was employed as a random effect. Systematic fixed effects were month of mating, mating type, age of the mare and stallion, reproductive status of the mare and stallion line of the mare. Inbreeding coefficients of the stallion, mare and expected foal were modelled as linear covariates. The average CFR was 40.9%. The mean inbreeding coefficients of the mares, stallions and expected foals were 7.46, 7.70 and 9.66%. Mating type, age of the mare, reproductive status of the mare and stallion line of the mare had a significant effect. The results showed that the mating type, stallion line of the mare, sire, age and reproductive status of the mare exerted the largest influences on CFR in BFDH. Inbreeding coefficients of the stallion, mare and expected foal were not significantly related with CFR.

Mutual mate choice: when it pays both sexes to avoid inbreeding.

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Mathieu Lihoreau

Full Text Available Theoretical models of sexual selection predict that both males and females of many species should benefit by selecting their mating partners. However, empirical evidence testing and validating this prediction is scarce. In particular, whereas inbreeding avoidance is expected to induce sexual conflicts, in some cases both partners could benefit by acting in concert and exerting mutual mate choice for non-assortative pairings. We tested this prediction with the gregarious cockroach Blattella germanica (L.. We demonstrated that males and females base their mate choice on different criteria and that choice occurs at different steps during the mating sequence. Males assess their relatedness to females through antennal contacts before deciding to court preferentially non-siblings. Conversely, females biased their choice towards the most vigorously courting males that happened to be non-siblings. This study is the first to demonstrate mutual mate choice leading to close inbreeding avoidance. The fact that outbred pairs were more fertile than inbred pairs strongly supports the adaptive value of this mating system, which includes no "best phenotype" as the quality of two mating partners is primarily linked to their relatedness. We discuss the implications of our results in the light of inbreeding conflict models.

RELATION OF INBREEDING OF HORSES OF THOROUGHBRED BREED WITH DEGREE OF HOMOZYGOSITY OF MICROSATELLITE LOCI OF DNA

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Melnyk О.V.

2013-09-01

Full Text Available The degree of homozygosity of some 39 Thoroughbred horses was estimated from microsatellite analysis data. The power of inbreeding was detected towards horse pedigree. We suggested the use of genetic analysis of microsatellite loci of DNA for the determination of actual level of inbreeding.

Evaluation of inbreeding in laying hens by applying optimum genetic contribution and gene flow theory.

Science.gov (United States)

König, S; Tsehay, F; Sitzenstock, F; von Borstel, U U; Schmutz, M; Preisinger, R; Simianer, H

2010-04-01

Due to consistent increases of inbreeding of on average 0.95% per generation in layer populations, selection tools should consider both genetic gain and genetic relationships in the long term. The optimum genetic contribution theory using official estimated breeding values for egg production was applied for 3 different lines of a layer breeding program to find the optimal allocations of hens and sires. Constraints in different scenarios encompassed restrictions related to additive genetic relationships, the increase of inbreeding, the number of selected sires and hens, and the number of selected offspring per mating. All these constraints enabled higher genetic gain up to 10.9% at the same level of additive genetic relationships or in lower relationships at the same gain when compared with conventional selection schemes ignoring relationships. Increases of inbreeding and genetic gain were associated with the number of selected sires. For the lowest level of the allowed average relationship at 10%, the optimal number of sires was 70 and the estimated breeding value for egg production of the selected group was 127.9. At the highest relationship constraint (16%), the optimal number of sires decreased to 15, and the average genetic value increased to 139.7. Contributions from selected sires and hens were used to develop specific mating plans to minimize inbreeding in the following generation by applying a simulated annealing algorithm. The additional reduction of average additive genetic relationships for matings was up to 44.9%. An innovative deterministic approach to estimate kinship coefficients between and within defined selection groups based on gene flow theory was applied to compare increases of inbreeding from random matings with layer populations undergoing selection. Large differences in rates of inbreeding were found, and they underline the necessity to establish selection tools controlling long-term relationships. Furthermore, it was suggested to use

Plant traits correlated with generation time directly affect inbreeding depression and mating system and indirectly genetic structure

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Hardy Olivier J

2009-07-01

Full Text Available Abstract Background Understanding the mechanisms that control species genetic structure has always been a major objective in evolutionary studies. The association between genetic structure and species attributes has received special attention. As species attributes are highly taxonomically constrained, phylogenetically controlled methods are necessary to infer causal relationships. In plants, a previous study controlling for phylogenetic signal has demonstrated that Wright's FST, a measure of genetic differentiation among populations, is best predicted by the mating system (outcrossing, mixed-mating or selfing and that plant traits such as perenniality and growth form have only an indirect influence on FST via their association with the mating system. The objective of this study is to further outline the determinants of plant genetic structure by distinguishing the effects of mating system on gene flow and on genetic drift. The association of biparental inbreeding and inbreeding depression with population genetic structure, mating system and plant traits are also investigated. Results Based on data from 263 plant species for which estimates of FST, inbreeding (FIS and outcrossing rate (tm are available, we confirm that mating system is the main influencing factor of FST. Moreover, using an alternative measure of FST unaffected by the impact of inbreeding on effective population size, we show that the influence of tm on FST is due to its impact on gene flow (reduced pollen flow under selfing and on genetic drift (higher drift under selfing due to inbreeding. Plant traits, in particular perenniality, influence FST mostly via their effect on the mating system but also via their association with the magnitude of selection against inbred individuals: the mean inbreeding depression increases from short-lived herbaceous to long-lived herbaceous and then to woody species. The influence of perenniality on mating system does not seem to be related to

Revealing gene action for production characteristics by inbreeding ...

African Journals Online (AJOL)

inbreeding coefficient on the mean of the characters in a two-way selection experiment for the slope (b) and intercept. (Ln (a)) of the ... ln (a) selection group, as well as average daily f-eed intake (Phase I and 2) of the b selection group. Die genewerking wat ..... exposed to natural selection for an extended period under con-.

Presence of inbreeding during a selection experiment with Merino ...

African Journals Online (AJOL)

Presence of inbreeding during a selection experiment with Merino sheep. GJ Erasmus, AO de Lange, GJ Delport, JJ Olivier. Abstract. No Abstract. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

Inbreeding and matrimonial structure in a Pyrenean community (Ansó, Huesca, Spain), 1712-1982.

Science.gov (United States)

Valls, A

1985-03-01

Using data from parish records from 1712 to 1982 in a Spanish Pyrenean village, Ansó, the effects of the raw nuptiality, the types of consanguineous marriages and the rate and evolution of inbreeding on the mating structure have been studied. This structure has been modified in the course of time mostly through the secular variations in the frequency of consanguineous marriages. Recent inbreeding decrease in Ansó is related to the population diminution and cultural changes associated with isolate breakdown.

Inbreeding depression and purging in a haplodiplois: gender-related effects

NARCIS (Netherlands)

Tien, N.S.H.; Sabelis, M.W.; Egas, M.

2015-01-01

Compared with diploid species, haplodiploids suffer less inbreeding depression because male haploidy imposes purifying selection on recessive deleterious alleles. However, alleles of genes only expressed in the diploid females are protected in heterozygous individuals. This leads to the prediction

Inbreeding Depression and Purging in a Haplodiploid: Gender-Related Effects

NARCIS (Netherlands)

Tien, N.S.H.; Sabelis, M.W.; Egas, M.

2015-01-01

Compared with diploid species, haplodiploids suffer less inbreeding depression because male haploidy imposes purifying selection on recessive deleterious alleles. However, alleles of genes only expressed in the diploid females are protected in heterozygous individuals. This leads to the prediction

Mapping the structural and dynamical features of multiple p53 DNA binding domains: insights into loop 1 intrinsic dynamics.

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Suryani Lukman

Full Text Available The transcription factor p53 regulates cellular integrity in response to stress. p53 is mutated in more than half of cancerous cells, with a majority of the mutations localized to the DNA binding domain (DBD. In order to map the structural and dynamical features of the DBD, we carried out multiple copy molecular dynamics simulations (totaling 0.8 μs. Simulations show the loop 1 to be the most dynamic element among the DNA-contacting loops (loops 1-3. Loop 1 occupies two major conformational states: extended and recessed; the former but not the latter displays correlations in atomic fluctuations with those of loop 2 (~24 Å apart. Since loop 1 binds to the major groove whereas loop 2 binds to the minor groove of DNA, our results begin to provide some insight into the possible mechanism underpinning the cooperative nature of DBD binding to DNA. We propose (1 a novel mechanism underlying the dynamics of loop 1 and the possible tread-milling of p53 on DNA and (2 possible mutations on loop 1 residues to restore the transcriptional activity of an oncogenic mutation at a distant site.

Demographic consequences of inbreeding and outbreeding in Arnica montana: A field experiment

Science.gov (United States)

Luijten, S.H.; Kery, M.; Oostermeijer, J.G.B.; Den, Nijs H.J.C.M.

2002-01-01

1. The genetic constitution of populations may significantly affect demography. Founder populations or isolated remnants may show inbreeding depression, while established populations can be strongly adapted to the local environment. Gene exchange between populations can lead to better performance if heterozygosity levels are restored (heterosis), or to reduced performance if coadapted gene complexes are disrupted (outbreeding depression). 2. Five populations of the self-incompatible perennial Arnica montana (Asteraceae) were analysed for the demographic consequences of inbreeding and of intra- and interpopulation outcrossing, using both small and large populations as donors for the latter. We analysed seed production and seed weight and monitored growth, survival and flowering of offspring introduced as seeds and as 4-week-old seedlings in a 4-year field experiment. 3. Reduced seed set after selfing was probably due to the self-incompatibility system rather than to inbreeding depression. There was a significant increase for seed set after interpopulation crosses, which resulted from the alleviation of low mate availability in one of the small populations. 4. Significant inbreeding depression was observed for growth rates of plants introduced as seedlings. We found significant heterosis for flowering probability of plants introduced as seeds, but for plants introduced as seedlings, heterosis for seedling size and flowering probability was only marginally significant. Outbreeding depression was not observed. 5. The results of this study are important for reinforcement measures in small, remnant populations. Significant differences among populations for all measured fitness components suggest that reinforcement is best achieved using material from several populations. 6. The observed higher survival of seedlings as compared with seeds suggests that it is better to plant individuals than to sow. Sowing, however, is easier and cheaper, and was more likely to eliminate

Rate of inbreeding and effective population size in four major South ...

African Journals Online (AJOL)

huis

Keywords: Dairy cattle, genetic diversity, pedigree analysis ... inbreeding and effective population sizes for the four major South African ... breeding programs and therefore L was computed as an average of generation intervals for the four.

Inbreeding effects on standard metabolic rate investigated at cold, benign and hot temperatures in Drosophila melanogaster

DEFF Research Database (Denmark)

Jensen, Palle; Overgaard, Johannes; Loeschcke, Volker

2014-01-01

in replicated lines of inbred and outbred Drosophila melanogaster at stressful low, benign and stressful high temperatures. The lowest measurements of metabolic rate in our study are always associated with the low activity period of the diurnal cycle and these measurements therefore serve as good estimates...... of standard metabolic rate. Due to the potentially added costs of genetic stress in inbred lines we hypothesized that inbred individuals have increased metabolic rate compared to outbred controls and that this is more pronounced at stressful temperatures due to synergistic inbreeding by environment...... interactions. Contrary to our hypothesis we found no significant difference in metabolic rate between inbred and outbred lines and no interaction between inbreeding and temperature. Inbreeding however effected the variance; the variance in metabolic rate was higher between the inbred lines compared...

Genome-wide estimates of coancestry and inbreeding in a closed herd of ancient Iberian pigs.

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María Saura

Full Text Available Maintaining genetic variation and controlling the increase in inbreeding are crucial requirements in animal conservation programs. The most widely accepted strategy for achieving these objectives is to maximize the effective population size by minimizing the global coancestry obtained from a particular pedigree. However, for most natural or captive populations genealogical information is absent. In this situation, microsatellites have been traditionally the markers of choice to characterize genetic variation, and several estimators of genealogical coefficients have been developed using marker data, with unsatisfactory results. The development of high-throughput genotyping techniques states the necessity of reviewing the paradigm that genealogical coancestry is the best parameter for measuring genetic diversity. In this study, the Illumina PorcineSNP60 BeadChip was used to obtain genome-wide estimates of rates of coancestry and inbreeding and effective population size for an ancient strain of Iberian pigs that is now in serious danger of extinction and for which very accurate genealogical information is available (the Guadyerbas strain. Genome-wide estimates were compared with those obtained from microsatellite and from pedigree data. Estimates of coancestry and inbreeding computed from the SNP chip were strongly correlated with genealogical estimates and these correlations were substantially higher than those between microsatellite and genealogical coefficients. Also, molecular coancestry computed from SNP information was a better predictor of genealogical coancestry than coancestry computed from microsatellites. Rates of change in coancestry and inbreeding and effective population size estimated from molecular data were very similar to those estimated from genealogical data. However, estimates of effective population size obtained from changes in coancestry or inbreeding differed. Our results indicate that genome-wide information represents a

Tree-loop duality relation beyond single poles

Energy Technology Data Exchange (ETDEWEB)

Bierenbaum, Isabella [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Buchta, Sebastian; Draggiotis, Petros; Malamos, Ioannis; Rodrigo, German [Valencia Univ. Paterna (Spain). Inst. de Fisica Corpuscular

2012-11-15

We develop the Tree-Loop Duality Relation for two- and three-loop integrals with multiple identical propagators (multiple poles). This is the extension of the Duality Relation for single poles and multi-loop integrals derived in previous publications. We prove a generalization of the formula for single poles to multiple poles and we develop a strategy for dealing with higher-order pole integrals by reducing them to single pole integrals using Integration By Parts.

Renormalization of loop functions for all loops

International Nuclear Information System (INIS)

Brandt, R.A.; Neri, F.; Sato, M.

1981-01-01

It is shown that the vacuum expectation values W(C 1 ,xxx, C/sub n/) of products of the traces of the path-ordered phase factors P exp[igcontour-integral/sub C/iA/sub μ/(x)dx/sup μ/] are multiplicatively renormalizable in all orders of perturbation theory. Here A/sub μ/(x) are the vector gauge field matrices in the non-Abelian gauge theory with gauge group U(N) or SU(N), and C/sub i/ are loops (closed paths). When the loops are smooth (i.e., differentiable) and simple (i.e., non-self-intersecting), it has been shown that the generally divergent loop functions W become finite functions W when expressed in terms of the renormalized coupling constant and multiplied by the factors e/sup -K/L(C/sub i/), where K is linearly divergent and L(C/sub i/) is the length of C/sub i/. It is proved here that the loop functions remain multiplicatively renormalizable even if the curves have any finite number of cusps (points of nondifferentiability) or cross points (points of self-intersection). If C/sub γ/ is a loop which is smooth and simple except for a single cusp of angle γ, then W/sub R/(C/sub γ/) = Z(γ)W(C/sub γ/) is finite for a suitable renormalization factor Z(γ) which depends on γ but on no other characteristic of C/sub γ/. This statement is made precise by introducing a regularization, or via a loop-integrand subtraction scheme specified by a normalization condition W/sub R/(C-bar/sub γ/) = 1 for an arbitrary but fixed loop C-bar/sub γ/. Next, if C/sub β/ is a loop which is smooth and simple except for a cross point of angles β, then W(C/sub β/) must be renormalized together with the loop functions of associated sets S/sup i//sub β/ = ]C/sup i/ 1 ,xxx, C/sup i//sub p/i] (i = 2,xxx,I) of loops C/sup i//sub q/ which coincide with certain parts of C/sub β/equivalentC 1 1 . Then W/sub R/(S/sup i//sub β/) = Z/sup i/j(β)W(S/sup j//sub β/) is finite for a suitable matrix Z/sup i/j

Two-loop polygon Wilson loops in N = 4 SYM

International Nuclear Information System (INIS)

Anastasiou, C.; Brandhuber, A.; Heslop, P.; Spence, B.; Travaglini, G.; Khoze, V.V.

2009-01-01

We compute for the first time the two-loop corrections to arbitrary n-gon lightlike Wilson loops in N = 4 supersymmetric Yang-Mills theory, using efficient numerical methods. The calculation is motivated by the remarkable agreement between the finite part of planar six-point MHV amplitudes and hexagon Wilson loops which has been observed at two loops. At n = 6 we confirm that the ABDK/BDS ansatz must be corrected by adding a remainder function, which depends only on conformally invariant ratios of kinematic variables. We numerically compute remainder functions for n = 7,8 and verify dual conformal invariance. Furthermore, we study simple and multiple collinear limits of the Wilson loop remainder functions and demonstrate that they have precisely the form required by the collinear factorisation of the corresponding two-loop n-point amplitudes. The number of distinct diagram topologies contributing to the n-gon Wilson loops does not increase with n, and there is a fixed number of 'master integrals', which we have computed. Thus we have essentially computed general polygon Wilson loops, and if the correspondence with amplitudes continues to hold, all planar n-point two-loop MHV amplitudes in the N = 4 theory.

[Inbreeding, endogamy and exogamy among relatives of schizophrenia patients].

Science.gov (United States)

Abaskuliev, A A; Skoblo, G V

1975-01-01

An increased frequency of consanguineous marriages among the parents of schizophrenic patients in comparison with the control group of exogenous-somatic patients (infections, trauma) was found. Endogamy among the parents of schizophrenic patients and the control group was practically the same. The data obtained indicate a certain, but not the leading, role of inbreeding in the etiology of schizophrenia.

Inbreeding affects locomotor activity in Drosophila melanogaster at different ages

DEFF Research Database (Denmark)

Manenti, Tommaso; Pertoldi, Cino; Nasiri Moghadam, Neda

2015-01-01

The ability to move is essential for many behavioural traits closely related to fitness. Here we studied the effect of inbreeding on locomotor activity (LA) of Drosophila melanogaster at different ages under both dark and light regimes. We expected to find a decreased LA in inbred lines compared...

Harbor porpoise Phocoena phocoena strandings on the Dutch coast: No genetic structure, but evidence of inbreeding

Science.gov (United States)

van der Plas-Duivesteijn, Suzanne J.; Smit, Femmie J. L.; van Alphen, Jacques J. M.; Kraaijeveld, Ken

2015-03-01

Conservation management in the North Sea is often motivated by the population size of marine mammals, like harbor porpoises Phocoena phocoena. In the Dutch part of the North Sea, sighting and stranding data are used to estimate population sizes, but these data give little insight into genetic structuring of the population. In this study we investigated genetic structure among animals stranded at different locations and times of year. We also tested whether there is a link between stranding and necropsy data, and genetic diversity. We made use of both mitochondrial (mtDNA) and microsatellite DNA analysis of samples from dead stranded porpoises along the Dutch coast during 2007. mtDNA analysis showed 6 variable positions in the control region, defining 3 different haplotypes. mtDNA haplotypes were not randomly distributed along the Dutch coastline. However, microsatellite analysis showed that these mtDNA haplotypes did not represent separate groups on a nuclear level. Furthermore, microsatellite analysis revealed no genotypic differences between seasons, locations or genders. The results of this study indicate that the Dutch population is panmictic. In contrast, heterozygosity levels were low, indicating some level of inbreeding in this population. However, this was not corroborated by other indices of inbreeding. This research provided insight into genetic structuring of stranded porpoises in 2007, but data from multiple years should be included to be able to help estimate population sizes.

A comparison of pedigree- and DNA-based measures for identifying inbreeding depression in the critically endangered Attwater's Prairie-chicken.

Science.gov (United States)

Hammerly, Susan C; Morrow, Michael E; Johnson, Jeff A

2013-11-01

The primary goal of captive breeding programmes for endangered species is to prevent extinction, a component of which includes the preservation of genetic diversity and avoidance of inbreeding. This is typically accomplished by minimizing mean kinship in the population, thereby maintaining equal representation of the genetic founders used to initiate the captive population. If errors in the pedigree do exist, such an approach becomes less effective for minimizing inbreeding depression. In this study, both pedigree- and DNA-based methods were used to assess whether inbreeding depression existed in the captive population of the critically endangered Attwater's Prairie-chicken (Tympanuchus cupido attwateri), a subspecies of prairie grouse that has experienced a significant decline in abundance and concurrent reduction in neutral genetic diversity. When examining the captive population for signs of inbreeding, variation in pedigree-based inbreeding coefficients (f(pedigree)) was less than that obtained from DNA-based methods (f(DNA)). Mortality of chicks and adults in captivity were also positively correlated with parental relatedness (r(DNA)) and f(DNA), respectively, while no correlation was observed with pedigree-based measures when controlling for additional variables such as age, breeding facility, gender and captive/release status. Further, individual homozygosity by loci (HL) and parental rDNA values were positively correlated with adult mortality in captivity and the occurrence of a lethal congenital defect in chicks, respectively, suggesting that inbreeding may be a contributing factor increasing the frequency of this condition among Attwater's Prairie-chickens. This study highlights the importance of using DNA-based methods to better inform management decisions when pedigrees are incomplete or errors may exist due to uncertainty in pairings. © 2013 John Wiley & Sons Ltd.

Random inbreeding, isonymy, and population isolates in Argentina.

Science.gov (United States)

Dipierri, José; Rodríguez-Larralde, Alvaro; Barrai, Italo; Camelo, Jorge López; Redomero, Esperanza Gutiérrez; Rodríguez, Concepción Alonso; Ramallo, Virginia; Bronberg, Rubén; Alfaro, Emma

2014-07-01

Population isolates are an important tool in identifying and mapping genes of Mendelian diseases and complex traits. The geographical identification of isolates represents a priority from a genetic and health care standpoint. The purpose of this study is to analyze the spatial distribution of consanguinity by random isonymy (F ST) in Argentina and its relationship with the isolates previously identified in the country. F ST was estimated from the surname distribution of 22.6 million electors registered for the year 2001 in the 24 provinces, 5 geographical regions, and 510 departments of the country. Statistically significant spatial clustering of F ST was determined using the SaTScan V5.1 software. F ST exhibited a marked regional and departamental variation, showing the highest values towards the North and West of Argentina. The clusters of high consanguinity by random isonymy followed the same distribution. Recognized Argentinean genetic isolates are mainly localized at the north of the country, in clusters of high inbreeding. Given the availability of listings of surnames in high-capacity storage devices for different countries, estimating F ST from them can provide information on inbreeding for all levels of administrative subdivisions, to be used as a demographic variable for the identification of isolates within the country for public health purposes.

Mathematical Modeling of Loop Heat Pipes with Multiple Capillary Pumps and Multiple Condensers. Part 1; Stead State Stimulations

Science.gov (United States)

Hoang, Triem T.; OConnell, Tamara; Ku, Jentung

2004-01-01

Loop Heat Pipes (LHPs) have proven themselves as reliable and robust heat transport devices for spacecraft thermal control systems. So far, the LHPs in earth-orbit satellites perform very well as expected. Conventional LHPs usually consist of a single capillary pump for heat acquisition and a single condenser for heat rejection. Multiple pump/multiple condenser LHPs have shown to function very well in ground testing. Nevertheless, the test results of a dual pump/condenser LHP also revealed that the dual LHP behaved in a complicated manner due to the interaction between the pumps and condensers. Thus it is redundant to say that more research is needed before they are ready for 0-g deployment. One research area that perhaps compels immediate attention is the analytical modeling of LHPs, particularly the transient phenomena. Modeling a single pump/single condenser LHP is difficult enough. Only a handful of computer codes are available for both steady state and transient simulations of conventional LHPs. No previous effort was made to develop an analytical model (or even a complete theory) to predict the operational behavior of the multiple pump/multiple condenser LHP systems. The current research project offered a basic theory of the multiple pump/multiple condenser LHP operation. From it, a computer code was developed to predict the LHP saturation temperature in accordance with the system operating and environmental conditions.

Multi-loop PWR modeling and hardware-in-the-loop testing using ACSL

International Nuclear Information System (INIS)

Thomas, V.M.; Heibel, M.D.; Catullo, W.J.

1989-01-01

Westinghouse has developed an Advanced Digital Feedwater Control System (ADFCS) which is aimed at reducing feedwater related reactor trips through improved control performance for pressurized water reactor (PWR) power plants. To support control system setpoint studies and functional design efforts for the ADFCS, an ACSL based model of the nuclear steam supply system (NSSS) of a Westinghouse (PWR) was generated. Use of this plant model has been extended from system design to system testing through integration of the model into a Hardware-in-Loop test environment for the ADFCS. This integration includes appropriate interfacing between a Gould SEL 32/87 computer, upon which the plant model executes in real time, and the Westinghouse Distributed Processing family (WDPF) test hardware. A development program has been undertaken to expand the existing ACSL model to include capability to explicitly model multiple plant loops, steam generators, and corresponding feedwater systems. Furthermore, the program expands the ADFCS Hardware-in-Loop testing to include the multi-loop plant model. This paper provides an overview of the testing approach utilized for the ADFCS with focus on the role of Hardware-in-Loop testing. Background on the plant model, methodology and test environment is also provided. Finally, an overview is presented of the program to expand the model and associated Hardware-in-Loop test environment to handle multiple loops

Inbreeding in the Danish populations of five Nordic sheep breeds

DEFF Research Database (Denmark)

Sørensen, Anders Christian; Norberg, Elise

2008-01-01

In Denmark there are small populations of five Nordic sheep breeds, two of which are Danish in origin. The purpose of this study was to estimate trends in inbreeding for these breeds. All five breeds have been recording pedigrees for decades, so pedigree completeness is adequate. The rate of inbr...

Genetic variation of inbreeding depression among floral and fitness traits in Silene nutans

DEFF Research Database (Denmark)

Thiele, Jan; Hansen, Thomas Møller; Siegismund, Hans Redlef

2010-01-01

The magnitude and variation of inbreeding depression (ID) within populations is important for the evolution and maintenance of mixed mating systems. We studied ID and its genetic variation in a range of floral and fitness traits in a small and large population of the perennial herb Silene nutans......, using controlled pollinations in a fully factorial North Carolina II design. Floral traits and early fitness traits, that is seed mass and germination rate, were not much affected by inbreeding (delta0.4). Lack of genetic correlations indicated that ID in floral, early and late traits is genetically...... was statistically significant in most floral and all seed traits, but not in late fitness traits. However, some paternal families had delta...

Inbreeding and its effect on some productive traits in buffaloes of South Iran

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B. Mahmoodi

2010-02-01

Full Text Available The buffalo is a native animal of Iran and there were 500,000 buffaloes in Iran that over 80 per cent of its population concentrated in the north and north- west (Azerbaijan province and 18 per cent in the south (Khuzestan province of the country. Buffaloes reread in rural condition as multi purpose animals in Khuzestan. For mating, farmer use owns herd sire also artificial insemination is limited in the rural condition that may be inbred animals so affect the production performance. The aim of this investigation was estimate the inbreeding coefficient and its affect on some production performance. Data of 200 herds were used from the record sheets of herds under recording program of Animal Breeding Center during period 1990 to 2002 in the Khuzestan province. These results showed mostly herds only one sir and rarely two sires have been used. Inbreeding coefficient was 25 percent in some progeny and high-inbred buffaloes had a low performance. According to results of this study it could be concluded that farmers to avoid inbreeding should use other herd sire and artificial insemination also practical recording scheme and genetically selection to genetic improvement should be included in buffaloes of Iran.

[Genetic isolates and inbreeding customs in three rural municipalities from Honduras].

Science.gov (United States)

Herrera-Paz, Edwin Francisco

2016-01-01

The isonymic method has been amply used to assess the approximate genetic structure of human communities. The objective of the study was to evaluate the magnitude of genetic isolation and inbreeding customs in 57 communities from three rural municipalities of Honduras using isonymy techniques. The list of 408 different surnames from 20712 voters registered in the national electoral organism, residing in the 57 Honduran communities, was used for this study. For each community, random (IR), non-random (IN), and total (IT) isonymy values were calculated in order to assess inbreeding coefficients FST, FIS and FIT. High consanguinity due to isolation and to endogamous customs was unveiled in many communities. Significant deviation from the exogamous behavior typical of many human populations was observed in the three studied municipalities, when compared to other Honduran populations. The studied communities present high consanguinity due to isolation, ethnic segregation and/or endogamous customs.

Inbreeding and Genetic Diversity in Three Imported Swine Breeds in China Using Pedigree Data

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G. Q. Tang

2013-06-01

Full Text Available The accumulation of inbreeding and the loss of genetic diversity is a potential problem in the modern swine breeds in China. Therefore, the purpose of this study was to analyze the pedigrees of Chinese Duroc (CD, Landrace (CL and Yorkshire (CY swine to estimate the past and current rates of inbreeding, and to identify the main causes of genetic diversity loss. Pedigree files from CD, CL and CY containing, 4529, 16,776 and 22,600 records, respectively, were analyzed. Pedigree completeness indexes of the three breeds, accounting for one generation back, were 83.72, 93.93 and 93.59%, respectively. The estimated average annual inbreeding rates for CD, CL and CY in recent three years were 0.21, 0.19 and 0.13%, respectively. The estimated average percentage of genetic diversity loss within each breed in recent three years was about 8.92, 2.19, and 3.36%, respectively. The average relative proportion of genetic diversity loss due to unequal contributions of founders in CD, CL and CY was 69.09, 57.95 and 60.57%, and due to random genetic drift was 30.91, 42.05 and 39.43%, respectively. The estimated current effective population size for CD, CL and CY was 76, 117 and 202, respectively. Therefore, CD has been found to have lost considerable genetic diversity, demanding priority for optimizing the selection and mating to control future coancestry and inbreeding. Unequal contribution of founders was a major cause of genetic diversity loss in Chinese swine breeds and random genetic drift also showed substantial impact on the loss of diversity.

A case of inbreeding in the African Wild Dog Lycaon pictus in the Kruger National Park

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A. Reich

1978-09-01

Full Text Available An observed case of inbreeding in a pack ot wild dogs Lycaon pictus in the Kruger National Park, Republic of South Africa, provides evidence for the phenomenon of dominance reversal in this species. This is believed to be the first recorded instance of inbreeding in Lycaon. Emigration of subordinate females from established packs of wild dogs has been documented in the Serengeti National Park and Ngorongoro Conservation Area in northern Tanzania, as well as in the Kruger National Park. However, the newly subordinate (ex-dominant female in the pack in which inbreeding has occurred has not emigrated in the 16 months since the change in her status. A possible explanation for this behaviour is given. As a result of this reversal, the pack contains at least two females capable of breeding, the subordinate of which is at least two years older than the dominant. This is considered the first record of such a breeding structure in Lycaon.

Heterotic effects in f/sub 1s/ and inbreeding depression in f/sub 2/ hybrids of sunflower

International Nuclear Information System (INIS)

Memon, S.; Baloch, M.J.; Baloch, G.M.

2015-01-01

genetically diverse female lines of sunflower were crossed with male testers to get heterotic hybrids. studies were carried-out during 2008-2010 at experiment filed of agriculture research institute, tandojam, sindh, pakistan. six female lines like t-4-0319, pac-0505, ho-i, hysun-33, peshawar-93 and cms-03 and three testers i.e., pac-0306, pac-64-a and sf-187 were crossed in a line * tester mating design, thus 18 f1 and f2 hybrids were developed for evaluation of heterosis and inbreeding depression for days to initial flowering, days to maturity, leaves/plant, plant height (cm), head diameter (cm), 1000-achene weight (g), seed yield kg/ha and oil yield kg/ha. the experiment was conducted in a randomised completeb lock design with four replications. the analysis of variance revealed significant differences among parents, f1s and f2 hybrids for all the traits studied. the existence of significant genetic variability among the plant traits is particularly useful because variations in these traits would allow further improvement in sunflower seed yield and oil traits. the f1 hybrids ho-i * pac-0306 and ho-i pa * c-64-a exhibited desirable negative mid and better parent heterosis for days to initial flowering, days to maturity and plant height. these hybrids also manifested desirable positive heterotic effects for leaves/plant, head diameter, 1000-achene.s weight, seed yield and oil yield. inbreeding depression for phenological, seed yield and oil traits showed that desirable high inbreeding depression was observed in hybrids ho-i * p*ac-64-a, ho-i * pac-0306 and ho-i * sf-187 for days to initial flowering, similarly t-4-0319 * pac-0306, pac-0505 ± sf-187 and ho-i * pac-64-a explicated maximum but rewarding inbreeding depression for days to maturity. the f2 hybrids hysun-33 * sf-187 and peshawer-93 * pac-64-a may be the most desirable ones in the sense that they recorded comparatively moderate inbreeding depression with enough number of leaves to be productive if f2

Slow inbred lines of Drosophila melanogaster express as much inbreeding depression as fast inbred lines under semi-natural conditions

DEFF Research Database (Denmark)

Kristensen, Torsten Nygård; Knudsen, Morten Ravn; Loeschcke, Volker

2011-01-01

Selection may reduce the deleterious consequences of inbreeding. This may be due to purging of recessive deleterious alleles or balancing selection favouring heterozygote offspring. Such selection is expected to be more efficient at slower compared to at faster rates of inbreeding. In this study ...

How much gene flow is needed to avoid inbreeding depression in wild tiger populations?

Science.gov (United States)

Kenney, John; Allendorf, Fred W; McDougal, Charles; Smith, James L D

2014-08-22

The number and size of tiger populations continue to decline owing to habitat loss, habitat fragmentation and poaching of tigers and their prey. As a result, tiger populations have become small and highly structured. Current populations have been isolated since the early 1970s or for approximately seven generations. The objective of this study is to explore how inbreeding may be affecting the persistence of remaining tiger populations and how dispersal, either natural or artificial, may reduce the potentially detrimental effect of inbreeding depression. We developed a tiger simulation model and used published levels of genetic load in mammals to simulate inbreeding depression. Following a 50 year period of population isolation, we introduced one to four dispersing male tigers per generation to explore how gene flow from nearby populations may reduce the negative impact of inbreeding depression. For the smallest populations, even four dispersing male tigers per generation did not increase population viability, and the likelihood of extinction is more than 90% within 30 years. Unless habitat connectivity is restored or animals are artificially introduced in the next 70 years, medium size wild populations are also likely to go extinct, with only four to five of the largest wild tiger populations likely to remain extant in this same period without intervention. To reduce the risk of local extinction, habitat connectivity must be pursued concurrently with efforts to increase population size (e.g. enhance habitat quality, increase habitat availability). It is critical that infrastructure development, dam construction and other similar projects are planned appropriately so that they do not erode the extent or quality of habitat for these populations so that they can truly serve as future source populations. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The Relationship between Runs of Homozygosity and Inbreeding in Jersey Cattle under Selection.

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Eui-Soo Kim

Full Text Available Inbreeding is often an inevitable outcome of strong directional artificial selection but on average it reduces population fitness with increased frequency of recessive deleterious alleles. Runs of homozygosity (ROH representing genomic autozygosity that occur from mating between selected and genomically related individuals may be able to reveal the regions affecting fitness. To examine the influence of genomic autozygosity on fitness, we used a genome-wide association test to evaluate potential negative correlations between ROH and daughter pregnancy rate (DPR or somatic cell score (SCS in US Jersey cattle. In addition, relationships between changes of local ROH and inbreeding coefficients (F were assessed to locate genomic regions with increased inbreeding. Despite finding some decreases in fertility associated with incremental increases in F, most emerging local ROH were not significantly associated with DPR or SCS. Furthermore, the analyses of ROH could be approximated with the most frequent haplotype(s, including the associations of ROH and F or traits. The analysis of the most frequent haplotype revealed that associations of ROH and fertility could be accounted for by the additive genetic effect on the trait. Thus, we suggest that a change of autozygosity is more likely to demonstrate footprints of selected haplotypes for production rather than highlight the possible increased local autozygosity of a recessive detrimental allele resulting from the mating between closely related animals in Jersey cattle.

Population structure and genomic inbreeding in nine Swiss dairy cattle populations.

Science.gov (United States)

Signer-Hasler, Heidi; Burren, Alexander; Neuditschko, Markus; Frischknecht, Mirjam; Garrick, Dorian; Stricker, Christian; Gredler, Birgit; Bapst, Beat; Flury, Christine

2017-11-07

Domestication, breed formation and intensive selection have resulted in divergent cattle breeds that likely exhibit their own genomic signatures. In this study, we used genotypes from 27,612 autosomal single nucleotide polymorphisms to characterize population structure based on 9214 sires representing nine Swiss dairy cattle populations: Brown Swiss (BS), Braunvieh (BV), Original Braunvieh (OB), Holstein (HO), Red Holstein (RH), Swiss Fleckvieh (SF), Simmental (SI), Eringer (ER) and Evolèner (EV). Genomic inbreeding (F ROH ) and signatures of selection were determined by calculating runs of homozygosity (ROH). The results build the basis for a better understanding of the genetic development of Swiss dairy cattle populations and highlight differences between the original populations (i.e. OB, SI, ER and EV) and those that have become more popular in Switzerland as currently reflected by their larger populations (i.e. BS, BV, HO, RH and SF). The levels of genetic diversity were highest and lowest in the SF and BS breeds, respectively. Based on F ST values, we conclude that, among all pairwise comparisons, BS and HO (0.156) differ more than the other pairs of populations. The original Swiss cattle populations OB, SI, ER, and EV are clearly genetically separated from the Swiss cattle populations that are now more common and represented by larger numbers of cows. Mean levels of F ROH ranged from 0.027 (ER) to 0.091 (BS). Three of the original Swiss cattle populations, ER (F ROH : 0.027), OB (F ROH : 0.029), and SI (F ROH : 0.039), showed low levels of genomic inbreeding, whereas it was much higher in EV (F ROH : 0.074). Private signatures of selection for the original Swiss cattle populations are reported for BTA4, 5, 11 and 26. The low levels of genomic inbreeding observed in the original Swiss cattle populations ER, OB and SI compared to the other breeds are explained by a lesser use of artificial insemination and greater use of natural service. Natural service

Inbreeding in Southeastern Spain : The Impact of Geography and Demography on Marital Mobility and Marital Distance Patterns (1900-1969).

Science.gov (United States)

Calderón, R; Hernández, C L; García-Varela, G; Masciarelli, D; Cuesta, P

2018-03-01

In this paper, the structure of a southeastern Spanish population was studied for the first time with respect to its inbreeding patterns and its relationship with demographic and geographic factors. Data on consanguineous marriages (up to second cousins) from 1900 to 1969 were taken from ecclesiastic dispensations. Our results confirm that the patterns and trends of inbreeding in the study area are consistent with those previously observed in most non-Cantabrian Spanish populations. The rate of consanguineous marriages was apparently stable between 1900 and 1935 and then sharply decreased since 1940, which coincides with industrialization in Spain. A marked departure from Hardy-Weinberg expectations (0.25) in the ratio of first cousin (M22) to second cousin (M33) marriages in the study population (0.88) was observed. The high levels of endogamy (>80%) and its significant steadiness throughout the twentieth century is noteworthy. Accordingly, our results show that exogamous marriages were not only poorly represented but also that this reduced mobility (relationships between population size and consanguinity rates and inbreeding fit power-law distributions. A significant positive correlation was observed between inbreeding and elevation. Many Spanish populations have experienced a prolonged and considerable isolation across generations, which has led to high proportions of historical and local endogamy that is associated, in general, with high [Formula: see text] values. Thus, assessing genomic inbreeding using runs of homozygosity (ROH) in current Spanish populations could be an additional pertinent strategy for obtaining a more refined perspective regarding the population history inferred from the extent and frequency of ROH regions.

Protein Structure Classification and Loop Modeling Using Multiple Ramachandran Distributions

KAUST Repository

Najibi, Seyed Morteza; Maadooliat, Mehdi; Zhou, Lan; Huang, Jianhua Z.; Gao, Xin

2017-01-01

Recently, the study of protein structures using angular representations has attracted much attention among structural biologists. The main challenge is how to efficiently model the continuous conformational space of the protein structures based on the differences and similarities between different Ramachandran plots. Despite the presence of statistical methods for modeling angular data of proteins, there is still a substantial need for more sophisticated and faster statistical tools to model the large-scale circular datasets. To address this need, we have developed a nonparametric method for collective estimation of multiple bivariate density functions for a collection of populations of protein backbone angles. The proposed method takes into account the circular nature of the angular data using trigonometric spline which is more efficient compared to existing methods. This collective density estimation approach is widely applicable when there is a need to estimate multiple density functions from different populations with common features. Moreover, the coefficients of adaptive basis expansion for the fitted densities provide a low-dimensional representation that is useful for visualization, clustering, and classification of the densities. The proposed method provides a novel and unique perspective to two important and challenging problems in protein structure research: structure-based protein classification and angular-sampling-based protein loop structure prediction.

Protein Structure Classification and Loop Modeling Using Multiple Ramachandran Distributions

KAUST Repository

Najibi, Seyed Morteza

2017-02-08

Recently, the study of protein structures using angular representations has attracted much attention among structural biologists. The main challenge is how to efficiently model the continuous conformational space of the protein structures based on the differences and similarities between different Ramachandran plots. Despite the presence of statistical methods for modeling angular data of proteins, there is still a substantial need for more sophisticated and faster statistical tools to model the large-scale circular datasets. To address this need, we have developed a nonparametric method for collective estimation of multiple bivariate density functions for a collection of populations of protein backbone angles. The proposed method takes into account the circular nature of the angular data using trigonometric spline which is more efficient compared to existing methods. This collective density estimation approach is widely applicable when there is a need to estimate multiple density functions from different populations with common features. Moreover, the coefficients of adaptive basis expansion for the fitted densities provide a low-dimensional representation that is useful for visualization, clustering, and classification of the densities. The proposed method provides a novel and unique perspective to two important and challenging problems in protein structure research: structure-based protein classification and angular-sampling-based protein loop structure prediction.

A Review of the Implications of Heterozygosity and Inbreeding on Germplasm Biodiversity and Its Conservation in the Silkworm, Bombyx mori

Science.gov (United States)

Jingade, A.H.; Vijayan, K.; Somasundaram, P.; Srivasababu, G.K.; Kamble, C.K.

2011-01-01

Silkworm genebanks assume paramount importance as the reservoirs of biodiversity and source of alleles that can be easily retrieved for genetic enhancement of popular breeds. More than 4000 Bombyx mori L (Lepidoptera: Bombycidae) strains are currently available and these strains are maintained through continuous sibling mating. This repeated sibling mating makes the populations of each strain more homozygous, but leads to loss of unique and valuable genes through the process of inbreeding depression. Hence, it is essential to maintain a minimal degree of heterozygosity within the population of each silkworm strain, especially in the traditional geographic strains, to avoid such loss. As a result, accurate estimation of genetic diversity is becoming more important in silkworm genetic resources conservation. Application of molecular markers help estimate genetic diversity much more accurately than that of morphological traits. Since a minimal amount of heterozygosity in each silkworm strain is essential for better conservation by avoiding inbreeding depression, this article overviews both theoretical and practical importance of heterozygosity together with impacts of inbreeding depression and the merits and demerits of neutral molecular markers for measurements of both heterozygosity and inbreeding depression in the silkworm Bombyx mori. PMID:21521139

AN ACTION OF EXOGENOUS STEROIDAL GLYCOSIDE ON EXHIBITION OF INBREEDING DEPRESSION IN RED BEET PLANTS UNDER PROTECTED CULTIVATION TECHNOLOGY

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E. G. Kozar

2017-01-01

Full Text Available The protected cultivation technology, through which the various inbred generations with the combination of economic valuable traits and different level of sterility can be produced, is used in order to accelerate the breeding program. However, there is a negative effect of inbreeding depression and self-incompatibility can often occur and cause the loss of valuable breeding forms. The aim of the work was to study the influence of steroidal glycosides capsicoside (SGC on exhibition of CMS, and morphobiological parameters of 13 inbred generations that were produced from fertile plant and partly sterile plants with level of sterility 10% and 50%. The seeds were soaked for 24 hours in water solution of SGC with concentration 10-3%, and in water control. Then the seeds were dried up and sown in the greenhouse. The stecklings and roots obtained were vernalized at 3-5Co. Mother plants were grown under 18 hour photoperiod in greenhouse with supplementary lighting. Inbreeding seeds were obtained in individual cloth isolators. It was shown that for all generations the treatment with SGC improved the seed germination (4-8% more, increased the root index and its length (12-24% more, decreased betanin content (22-48% less in comparison with control. The action of SGC on the other morphological and biochemical traits such as height of leaf rosette, leaf number, plant and root weight, head size, number of generative buds, and nitrate content was defined by the level of sterility of mother plant. The most expressed effect for all traits mentioned was seen in inbreeding generations of sterile plants with high level of sterility. After action effect of seed treatment with SGC on development of seed plants from inbreeding generations, not depending on sterility level of mother plants, showed the positive influence on plant habitus of seed mother plants, decreasing the plant height, but increasing stem number and functional parameters of microgametophyte in fertile

Evaluation of Inbreeding and Genetic Variability of Five Pig Breeds in Czech Republic

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E. Krupa

2015-01-01

Full Text Available The complex analysis of the pedigree records of Czech Landrace (CLA, Czech Large White-dam line (CLWd, Czech Large White-sire line (CLWs, Duroc (DC, and Pietrain (PN was performed to determine trends of genetic diversity (GD, and to find the main sources of the GD loss. The total size of the pedigree was 132,365, 391,151, 32,913, 13,299, and 7,160 animals in CLA, CLWd, CLWs, DC, and PN, respectively. Animals born in the years 2011 through 2013 were assumed as the reference population. The average pedigree completeness index for one generation back was 95.9%, 97.4%, 91.2%, 89.8%, and 94.2% for appropriate breeds. Number of ancestors explaining 100% of gene pool was 186, 373, 125, 157, and 37 in CLA, CLWd, CLWs, DC, and PN, respectively. The relative proportion of inbred animals (58%, 58%, 54%, 47%, and 25%, the average inbreeding (2.7%, 1.4%, 2.5%, 3.6%, and 1.3% and the average co-ancestry (3.1%, 1.6%, 3.3%, 4.2%, and 3.3% were found over the past decade in analysed breeds. The expected inbreeding under random mating increased during the last 10 years in CLWs and PN and varied from 1.27% to 3.2%. The effective population size computed on the basis of inbreeding was 76, 74, 50, 35, and 83 in 2012 in CLA, CLWd, CLWs, DC, and PN, respectively. The shortest generation interval (1.45 was observed for CLWd in sire to son selection pathway. The longest generation interval obtained PN (1.95 in sire to daughter pathway. The average relative GD loss within last generation interval was 7.05%, 4.70%, 9.81%, 7.47%, and 10.46%, respectively. The relative proportion of GD loss due to genetic drift on total GD loss was 85.04%, 84.51%, 89.46%, 86.19%, and 83.68% in CLA, CLWd, CLWs, DC, and PN, respectively. All breeds were characterized by a high proportion of inbred animals, but the average inbreeding was low. The most vulnerable breeds to loss of GD are DC and PN. Therefore, a breeding program should be more oriented to prevent the increase of GD loss in these

Pedigrees or markers: Which are better in estimating relatedness and inbreeding coefficient?

Science.gov (United States)

Wang, Jinliang

2016-02-01

Individual inbreeding coefficient (F) and pairwise relatedness (r) are fundamental parameters in population genetics and have important applications in diverse fields such as human medicine, forensics, plant and animal breeding, conservation and evolutionary biology. Traditionally, both parameters are calculated from pedigrees, but are now increasingly estimated from genetic marker data. Conceptually, a pedigree gives the expected F and r values, FP and rP, with the expectations being taken (hypothetically) over an infinite number of individuals with the same pedigree. In contrast, markers give the realised (actual) F and r values at the particular marker loci of the particular individuals, FM and rM. Both pedigree (FP, rP) and marker (FM, rM) estimates can be used as inferences of genomic inbreeding coefficients FG and genomic relatedness rG, which are the underlying quantities relevant to most applications (such as estimating inbreeding depression and heritability) of F and r. In the pre-genomic era, it was widely accepted that pedigrees are much better than markers in delineating FG and rG, and markers should better be used to validate, amend and construct pedigrees rather than to replace them. Is this still true in the genomic era when genome-wide dense SNPs are available? In this simulation study, I showed that genomic markers can yield much better estimates of FG and rG than pedigrees when they are numerous (say, 10(4) SNPs) under realistic situations (e.g. genome and population sizes). Pedigree estimates are especially poor for species with a small genome, where FG and rG are determined to a large extent by Mendelian segregations and may thus deviate substantially from their expectations (FP and rP). Simulations also confirmed that FM, when estimated from many SNPs, can be much more powerful than FP for detecting inbreeding depression in viability. However, I argue that pedigrees cannot be replaced completely by genomic SNPs, because the former allows for

Sex-biased natal dispersal and inbreeding avoidance in American black bears as revealed by spatial genetic analyses.

Science.gov (United States)

Costello, Cecily M; Creel, Scott R; Kalinowski, Steven T; Vu, Ninh V; Quigley, Howard B

2008-11-01

We tested the hypothesis that sex-biased natal dispersal reduces close inbreeding in American black bears, a solitary species that exhibits nearly complete male dispersal and female philopatry. Using microsatellite DNA and spatial data from reproductively mature bears (>or= 4 years old), we examined the spatial genetic structure of two distinct populations in New Mexico from 1993 to 2000. As predicted, relatedness (r) and the frequency of close relationships (parent-offspring or full siblings) decreased with distance among female dyads, but little change was observed among male or opposite-sex dyads. Neighbouring females were more closely related than neighbouring males. The potential for inbreeding was low. Most opposite-sex pairs that lived sufficiently close to facilitate mating were unrelated, and few were close relatives. We found no evidence that bears actively avoided inbreeding in their selection of mates from this nearby pool, as mean r and relationship frequencies did not differ between potential and actual mating pairs (determined by parentage analysis). These basic patterns were apparent in both study areas despite a nearly two-fold difference in density. However, the sex bias in dispersal was less pronounced in the lower-density area, based on proportions of bears with male and female relatives residing nearby. This result suggests that male bears may respond to reduced competition by decreasing their rate or distance of dispersal. Evidence supports the hypothesis that inbreeding avoidance is achieved by means of male-biased dispersal but also indicates that competition (for mates or resources) modifies dispersal patterns.

Multitarget multisensor closed-loop tracking

Science.gov (United States)

Sanders-Reed, John N.

2004-07-01

This paper describes a closed-loop tracking system using multiple co-located sensors to develop multi-sensor track histories on multiple targets. The use of multiple, co-aligned sensors to track multiple, possibly maneuvering targets, presents a number of tracker design challenges and opportunities. Many of these problems have been addressed individually in the published literature from a theoretical point of view. However, no one has yet addressed the design and implementation of a specific tracker to meet all of these requirements at once. Specific questions addressed in this paper include how to assign N detections in a current frame to M active tracks, how to initiate new tracks and terminate dead tracks, how to combine information from multiple sensors into a single integrated picture, represented by a global track file, and how to perform these functions in a timely manner to support a precision closed loop tracking system.

Fitness drivers in the threatened Dianthus guliae Janka (Caryophyllaceae): disentangling effects of growth context, maternal influence and inbreeding depression.

Science.gov (United States)

Gargano, D; Gullo, T; Bernardo, L

2011-01-01

We studied inbreeding depression, growth context and maternal influence as constraints to fitness in the self-compatible, protandrous Dianthus guliae Janka, a threatened Italian endemic. We performed hand-pollinations to verify outcomes of self- and cross-fertilisation over two generations, and grew inbred and outbred D. guliae offspring under different conditions - in pots, a common garden and field conditions (with/without nutrient addition). The environment influenced juvenile growth and flowering likelihood/rate, but had little effect on inbreeding depression. Significant interactions among genetic and environmental factors influenced female fertility. Overall, genetic factors strongly affected both early (seed mass, seed germination, early survival) and late (seed/ovule ratio) life-history traits. After the first pollination experiment, we detected higher mortality in the selfed progeny, which is possibly a consequence of inbreeding depression caused by over-expression of early-acting deleterious alleles. The second pollination induced a strong loss of reproductive fitness (seed production, seed mass) in inbred D. guliae offspring, regardless of the pollination treatment (selfing/crossing); hence, a strong (genetic) maternal influence constrained early life-history traits of the second generation. Based on current knowledge, we conclude that self-compatibility does not prevent the detrimental effects of inbreeding in D. guliae populations, and may increase the severe extinction risk if out-crossing rates decrease. © 2010 German Botanical Society and The Royal Botanical Society of the Netherlands.

Heterosis and inbreeding depression for panicle characters in crosses involving induced mutants of aromatic rice

International Nuclear Information System (INIS)

Hasib, K.M.

2001-01-01

Twelve crosses of aromatic rice utilizing four γ-ray induced mutants 88-8-3 and 33-9-15 of Tulaipanja and 124-17-4 and 21-6-1 of Gobindabhog and three basmati varieties were evaluated for heterosis and inbreeding depression for different panicle characters. All the hybrids except the two hybrids of 124-17-4 with Pakistan Basmati and Pusa Basmati I manifested significantly positive heterosis for grain yield panicle -1 . High magnitude of heterosis coupled with positive inbreeding depression for panicle length, secondary branches panicle -1 , spikelet number panicle -1 , panicle weight and grain yield panicle -1 in several crosses indicating the presence of nonadditive gene action. The results indicate the scope of exploiting heterosis in aromatic rice. (author)

Métodos de estimação do coeficiente de endogamia em uma população diplóide com alelos múltiplos Methods of estimation of the inbreeding coefficient in a diploid population with multiple alleles

Directory of Open Access Journals (Sweden)

Joel Augusto Muniz

2008-02-01

Full Text Available Com o presente trabalho, objetivou-se avaliar as propriedades de três estimadores do coeficiente de endogamia, F, em uma população diplóide com alelos múltiplos, por meio de dados de frequências alélicas de amostras de indíviduos, obtidas em populações simuladas, por meio do SAS. Foram avaliados o estimador de F, obtido pela média das estimativas nas análises de cada alelo, o estimador considerando a análise conjunta envolvendo todos os alelos, bem como aquele por meio de análise multivariada com os três alelos proposto por Long (1986. Os resultados encontrados para a média e variância dos estimadores, a partir de 1000 estimativas de F, calculadas para cada tamanho de amostra, mostraram que os três estimadores são tendenciosos. Entretanto, de maneira geral, observou-se que o estimador considerando a análise de variância conjunta foi menos tendencioso e apresentou menor variância, quando o coeficiente de endogamia na população era alto, enquanto que para populações com endogamia baixa a variância do estimador considerando a análise multivariada foi menor.The present work evaluted the properties of three estimators of the inbreeding coefficient, F, in a diploid population with multiple alleles, using data of gene frequencies in individuals from random samples, obtained in simulate populations, through the SAS. Were evaluted the estimator of F, obtained by single and joint univariate analysis and the estimator of F obtained by multivariate analysis as proposed by Long (1986. The analysis of the means and variances of the estimators, obtained of 1000 estimates of F, calculated for each sample size, it demonstrated that the three estimators is bias. However, it was observed that the estimator obtained of univariate analysis it was less biased and it presented smaller variance, when the inbreeding coefficient in the population was elevated, while for populations with low inbreeding, the variance of, the estimator obtained

Variation in parent–offspring kinship in socially monogamous systems with extra‐pair reproduction and inbreeding

Science.gov (United States)

Reid, Jane M.; Bocedi, Greta; Nietlisbach, Pirmin; Duthie, A. Bradley; Wolak, Matthew E.; Gow, Elizabeth A.; Arcese, Peter

2016-01-01

Female extra‐pair reproduction in socially monogamous systems is predicted to cause cuckolded socially‐paired males to conditionally reduce paternal care, causing selection against extra‐pair reproduction and underlying polyandry. However, existing models and empirical studies have not explicitly considered that cuckolded males might be related to their socially‐paired female and/or to her extra‐pair mate, and therefore be related to extra‐pair offspring that they did not sire but could rear. Selection against paternal care, and hence against extra‐pair reproduction, might then be weakened. We derive metrics that quantify allele‐sharing between within‐pair and extra‐pair offspring and their mother and her socially‐paired male in terms of coefficients of kinship and inbreeding. We use song sparrow (Melospiza melodia) paternity and pedigree data to quantify these metrics, and thereby quantify the joint effects of extra‐pair reproduction and inbreeding on a brood's total allelic value to its socially‐paired parents. Cuckolded male song sparrows were almost always detectably related to extra‐pair offspring they reared. Consequently, although brood allelic value decreased substantially following female extra‐pair reproduction, this decrease was reduced by within‐pair and extra‐pair reproduction among relatives. Such complex variation in kinship within nuclear families should be incorporated into models considering coevolutionary dynamics of extra‐pair reproduction, parental care, and inbreeding. PMID:27174154

The massless two-loop two-point function

International Nuclear Information System (INIS)

Bierenbaum, I.; Weinzierl, S.

2003-01-01

We consider the massless two-loop two-point function with arbitrary powers of the propagators and derive a representation from which we can obtain the Laurent expansion to any desired order in the dimensional regularization parameter ε. As a side product, we show that in the Laurent expansion of the two-loop integral only rational numbers and multiple zeta values occur. Our method of calculation obtains the two-loop integral as a convolution product of two primitive one-loop integrals. We comment on the generalization of this product structure to higher loop integrals. (orig.)

Estimates of genetic parameters, genetic trends, and inbreeding in a crossbred dairy sheep research flock in the United States.

Science.gov (United States)

Murphy, T W; Berger, Y M; Holman, P W; Baldin, M; Burgett, R L; Thomas, D L

2017-10-01

For the past 2 decades, the Spooner Agriculture Research Station (ARS) of the University of Wisconsin-Madison operated the only dairy sheep research flock in North America. The objectives of the present study were to 1) obtain estimates of genetic parameters for lactation and reproductive traits in dairy ewes, 2) estimate the amount of genetic change in these traits over time, and 3) quantify the level of inbreeding in this flock over the last 20 yr. Multiple-trait repeatability models (MTRM) were used to analyze ewe traits through their first 6 parities. The first MTRM jointly analyzed milk (180-d-adjusted milk yield [180d MY]), fat (180-d-adjusted fat yield [180d FY]), and protein (180-d-adjusted protein yield [180d PY]) yields adjusted to 180 d of lactation; number of lambs born per ewe lambing (NLB); and lactation average test-day somatic cell score (LSCS). A second MTRM analyzed 180d MY, NLB, LSCS, and percentage milk fat (%F) and percentage milk protein (%P). The 3 yield traits were moderately heritable (0.26 to 0.32) and strongly genetically correlated (0.91 to 0.96). Percentage milk fat and %P were highly heritable (0.53 and 0.61, respectively) and moderately genetically correlated (0.61). Milk yield adjusted to 180 d was negatively genetically correlated with %F and %P (-0.31 and -0.34, respectively). Ewe prolificacy was not significantly ( > 0.67) genetically correlated with yield traits, %P, or LSCS but lowly negatively correlated with %F (-0.26). Lactation somatic cell score was unfavorably genetically correlated with yield traits (0.28 to 0.39) but not significantly ( > 0.09) correlated with %F, %P, and NLB. Within-trait multiple-trait models through the first 4 parities revealed that 180d MY, 180d FY, 180d PY, %F, and %P were strongly genetically correlated across parity (0.67 to 1.00). However, the genetic correlations across parity for NLB and LSCS were somewhat lower (0.51 to 0.96). Regressing predicted breeding values for 180d MY, without and with

Measuring Temperature-Dependent Propagating Disturbances in Coronal Fan Loops Using Multiple SDO-AIA Channels and Surfing Transform Technique

Science.gov (United States)

Uritskiy, Vadim M.; Davila, Joseph M.; Viall, Nicholeen M.; Ofman, Leon

2013-01-01

A set of co-aligned high resolution images from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO) is used to investigate propagating disturbances (PDs) in warm fan loops at the periphery of a non-flaring active region NOAA AR 11082. To measure PD speeds at multiple coronal temperatures, a new data analysis methodology is proposed enabling quantitative description of sub visual coronal motions with low signal-to-noise ratios of the order of 0.1. The technique operates with a set of one-dimensional surfing signals extracted from position-timeplots of several AIA channels through a modified version of Radon transform. The signals are used to evaluate a two-dimensional power spectral density distribution in the frequency - velocity space which exhibits a resonance in the presence of quasi-periodic PDs. By applying this analysis to the same fan loop structures observed in several AIA channels, we found that the traveling velocity of PDs increases with the temperature of the coronal plasma following the square root dependence predicted for the slow mode magneto-acoustic wave which seems to be the dominating wave mode in the studied loop structures. This result extends recent observations by Kiddie et al. (2012) to a more general class of fan loop systems not associated with sunspots and demonstrating consistent slow mode activity in up to four AIA channels.

Heterosis at Allozyme Loci under Inbreeding and Crossbreeding in PINUS ATTENUATA

OpenAIRE

Strauss, Steven H.

1986-01-01

The dependence of heterosis at isozyme loci on inbreeding and crossbreeding was studied in 10-yr-old trees of knobcone pine (Pinus attenuata Lemm.). Heterozygosity was determined at 24 polymorphic isozyme loci and related to the rate of vegetative growth and cone production. The inbreds, created by selfpollination, had 46% of the heterozygosity of their mothers; the crossbreds, created by interpopulation crossing, had 155% of the heterozygosity of their mothers. Within the crossbreds, hetero...

Lack of nucleotide variability in a beetle pest with extreme inbreeding

OpenAIRE

Andreev, D.; Breilid, H.; Kirkendall, L.; Brun, Luc-Olivier; French-Constant, R.H.

1998-01-01

The coffee berry borer beetle #Hypothenemus hampei$ (Ferrari) (#Curculionidae$ : #Scolytinae$) is the major insect pest of coffee and has spread to most of the coffee-growing countries of the world. This beetle also displays an usual life cycle, with regular sibling mating. This regular inbreeding and the population bottlenecks occuring on colonization of new regions should lead to low levels of genetic diversity. We were therefore interested in determining the level of nucleotide variation i...

The effects of inbreeding and heat stress on male sterility in Drosophila melanogaster

DEFF Research Database (Denmark)

Pedersen, Louise Dybdahl; Pedersen, Asger Roer; Bijlsma, Kuke

2011-01-01

in benign and stressful environments using Drosophila melanogaster as a model organism. Male sterility was compared in 21 inbred lines and five non-inbred control lines at 25.0 and 29.0 °C. The effect of inbreeding on sterility was significant only at 29.0 °C. This stress-induced increase in sterility...

Adult nutrition, but not inbreeding, affects male primary sexual traits in the leaf-footed cactus bug Narnia femorata (Hemiptera: Coreidae).

Science.gov (United States)

Joseph, Paul N; Sasson, Daniel A; Allen, Pablo E; Somjee, Ummat; Miller, Christine W

2016-07-01

Adverse conditions may be the norm rather than the exception in natural populations. Many populations experience poor nutrition on a seasonal basis. Further, brief interludes of inbreeding can be common as population density fluctuates and because of habitat fragmentation. Here, we investigated the effects of poor nutrition and inbreeding on traits that can be very important to reproductive success and fitness in males: testes mass, sperm concentration, and sperm viability. Our study species was Narnia femorata, a species introduced to north-central Florida in the 1950s. This species encounters regular, seasonal changes in diet that can have profound phenotypic effects on morphology and behavior. We generated inbred and outbred individuals through a single generation of full-sibling mating or outcrossing, respectively. All juveniles were provided a natural, high-quality diet of Opuntia humifusa cactus cladode with fruit until they reached adulthood. New adult males were put on a high- or low-quality diet for at least 21 days before measurements were taken. As expected, the low-quality diet led to significantly decreased testes mass in both inbred and outbred males, although there were surprisingly no detectable effects on sperm traits. We did not find evidence that inbreeding affected testes mass, sperm concentration, and sperm viability. Our results highlight the immediate and overwhelming effects of nutrition on testes mass, while suggesting that a single generation of inbreeding might not be detrimental for primary sexual traits in this particular population.

Cooling Active Region Loops Observed With SXT and TRACE

OpenAIRE

Winebarger, Amy R.; Warren, Harry P.

2005-01-01

An Impulsive Heating Multiple Strand (IHMS) Model is able to reproduce the observational characteristics of EUV (~ 1 MK) active region loops. This model implies that some of the loops must reach temperatures where X-ray filters are sensitive (> 2.5 MK) before they cool to EUV temperatures. Hence, some bright EUV loops must be preceded by bright X-ray loops. Previous analysis of X-ray and EUV active region observations, however, have concluded that EUV loops are not preceded by X-ray loops. In...

Closed-Loop Surface Related Multiple Estimation

NARCIS (Netherlands)

Lopez Angarita, G.A.

2016-01-01

Surface-related multiple elimination (SRME) is one of the most commonly used methods for suppressing surface multiples. However, in order to obtain an accurate surface multiple estimation, dense source and receiver sampling is required. The traditional approach to this problem is performing data

Effects of seed size, inbreeding and maternal sex on offspring fitness in gynodioecious Plantago coronopus

NARCIS (Netherlands)

Koelewijn, H.P.; Damme, van J.M.M.

2005-01-01

1 Male steriles (MS) must have a fitness advantage relative to hermaphrodites (H) if they are to be maintained in gynodioecious species. We report experiments in which we disentangle the relative contributions of seed size, inbreeding and maternal sex to the fitness advantage of male steriles in

Optimal inventory policy in a closed loop supply chain system with multiple periods

International Nuclear Information System (INIS)

Sasi Kumar, A.; Natarajan, K.; Ramasubramaniam, Muthu Rathna Sapabathy.; Deepaknallasamy, K.K.

2017-01-01

Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods. The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C) for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

Optimal inventory policy in a closed loop supply chain system with multiple periods

Energy Technology Data Exchange (ETDEWEB)

Sasi Kumar, A.; Natarajan, K.; Ramasubramaniam, Muthu Rathna Sapabathy.; Deepaknallasamy, K.K.

2017-07-01

Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods. The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C) for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

Optimal inventory policy in a closed loop supply chain system with multiple periods

Directory of Open Access Journals (Sweden)

SasiKumar A.

2017-05-01

Full Text Available Purpose: This paper aims to model and optimize the closed loop supply chain for maximizing the profit by considering the fixed order quantity inventory policy in various sites at multiple periods. Design/methodology/approach: In forward supply chain, a standard inventory policy can be followed when the product moves from manufacturer, distributer, retailer and customer but the inventory in the reverse supply chain of the product with the similar standard policy is very difficult to manage. This model investigates the standard policy of fixed order quantity by considering the three major types of return-recovery pair such as commercial returns, end- of- use returns, end –of- life returns and their inventory positioning at multiple periods.  The model is configured as mixed integer linear programming and solved by IBM ILOG CPLEX OPL studio. Findings: To find the performance of the model a numerical example is considered for a product with three Parts (A which of 2nos, B and C for 12 multiple periods. The results of the analysis show that the manufacturer can know how much should to be manufacture in multiple periods based on Variations of the demand by adopting the FOQ inventory policy at different sites considering its capacity constraints. In addition, it is important how much of parts should be purchased from the supplier at the given 12 periods. Originality/value: A sensitivity analysis is performed to validate the proposed model two parts. First part of the analysis will focus on the inventory of product and parts and second part of analysis focus on profit of the company. The analysis which provides some insights in to the structure of the model.

Inbreeding and immigration in urban and rural zones of Chile, with an endogamy index.

Science.gov (United States)

Lazo, B; Campusano, C; Figueroa, H; Pinto-Cisternas, J; Zambra, E

1978-01-01

In order to establish relationships among immigration, inbreeding, and age at marriage in urban and rural zones in Chile, and to formulate an endogamy index, ecclesiastical and civil data on consanguinity from 1865-1914 were analyzed, and a random mating deviation index was developed, with resulting values indicating deviation toward endogamy in both zones. Data grouped by zones and decades include means of population and density, nuptiality, consanguineous marriages (number, types, frequencies, and inbreeding coefficients), and frequencies of immigrants among consanguineous and nonconsanguineous couples. All of these values differ markedly between zones, with values in the rural zone double those in the urban zone. In the 2 zones, there are no clear differences in age at marriage between consanguineous and nonconsanguineous couples, and this is an important finding. From the point of view of fertility, one can expect a similar length period of fertility for both groups of couples. In this case, lower fertility might be expected in consanguineous marriages, only because of a higher probability of homozygosis of deleterious genes.

Fundamental and Harmonic Oscillations in Neighboring Coronal Loops

Science.gov (United States)

Li, Hongbo; Liu, Yu; Vai Tam, Kuan

2017-06-01

We present observations of multimode (fundamental and harmonic) oscillations in a loop system, which appear to be simultaneously excited by a GOES C-class flare. Analysis of the periodic oscillations reveals that (1) the primary loop with a period of P a ≈ 4 minutes and a secondary loop with two periods of P a ≈ 4 minutes and P b ≈ 2 minutes are detected simultaneously in closely spaced loop strands; (2) both oscillation components have their peak amplitudes near the loop apex, while in the second loop the low-frequency component P a dominates in a loop segment that is two times larger than the high-frequency component P b ; (3) the harmonic mode P b shows the largest deviation from a sinusoidal loop shape at the loop apex. We conclude that multiple harmonic modes with different displacement profiles can be excited simultaneously even in closely spaced strands, similar to the overtones of a violin string.

The use (or misuse) of microsatellite allelic distances in the context of inbreeding and conservation genetics.

Science.gov (United States)

Hansson, Bengt

2010-03-01

In line with inbreeding theory, genetic diversity at a set of molecular markers may explain variation in fitness-associated traits in partially inbred populations, and such associations will appear as 'genotype-fitness correlations'. An individual genetic diversity index specifically used for microsatellites is 'mean d(2)', i.e. the mean squared distance between alleles. The original hypothesis for mean d(2)-fitness correlations assumes that mean d(2) captures fitness effects at both ends of the inbreeding-outbreeding spectrum. This hypothesis received strong criticism from work showing that even a plain diversity estimate such as multi-locus heterozygosity (MLH) outperforms mean d(2) as a predictor of the inbreeding coefficient and fitness in most realistic situations. Despite this critique, the mean d(2)-approach is still used frequently in ecological and evolutionary research, producing results suggesting that mean d(2) sometimes provides a stronger prediction of fitness than does MLH. In light of the critique, such results are unexpected, but potential explanations for them may exist (at least hypothetically), including scenarios based on close linkage and recent admixture. Nevertheless, a major caveat is that it is very difficult to predict a priori if mean d(2) will improve the genotype-fitness correlation, which in turn makes objective interpretations difficult. Mean d(2)-fitness associations are potentially interesting, but the fact that we cannot easily understand them is problematic and should be thoroughly addressed in each study. Therefore, instead of hastily reached interpretations of mean d(2)-fitness correlations, conclusions need support from complementary analyses, e.g. verifying admixture of genetically structured populations.

Cosmological perturbation theory using the FFTLog: formalism and connection to QFT loop integrals

Science.gov (United States)

Simonović, Marko; Baldauf, Tobias; Zaldarriaga, Matias; Carrasco, John Joseph; Kollmeier, Juna A.

2018-04-01

We present a new method for calculating loops in cosmological perturbation theory. This method is based on approximating a ΛCDM-like cosmology as a finite sum of complex power-law universes. The decomposition is naturally achieved using an FFTLog algorithm. For power-law cosmologies, all loop integrals are formally equivalent to loop integrals of massless quantum field theory. These integrals have analytic solutions in terms of generalized hypergeometric functions. We provide explicit formulae for the one-loop and the two-loop power spectrum and the one-loop bispectrum. A chief advantage of our approach is that the difficult part of the calculation is cosmology independent, need be done only once, and can be recycled for any relevant predictions. Evaluation of standard loop diagrams then boils down to a simple matrix multiplication. We demonstrate the promise of this method for applications to higher multiplicity/loop correlation functions.

Effect of population outcrossing rate on inbreeding depression in Pinus contorta var. murrayana seedlings.

Science.gov (United States)

Frank C. Sorensen

2001-01-01

Seft and cross families from three populatons (A, low-density, ecologically marginal site for lodgepole pine, and B + C, normal sites) were cultured in a common outdoor nursery for 2 yrs. Previous results results had shown higher natural selfing rates and lower inbreeding depression in embryo survival in A than in B + C. In the nursery test, selfing decreased means of...

Resilience of Urban Smart Grids Involving Multiple Control Loops

DEFF Research Database (Denmark)

Madsen, Jacob Theilgaard; Pillai, Jayakrishnan Radhakrishna; Schwefel, Hans-Peter

2016-01-01

Intelligent control of energy distribution grids is implemented via a hierarchy of control loops with different input values and different control targets, which also work on different time-scales. This control is enabled by a bi-directional communication flow, which can be interrupted due to ICT...

Steam drum level dynamics in a multiple loop natural circulation system of a pressure-tube type boiling water reactor

International Nuclear Information System (INIS)

Jain, Vikas; Kulkarni, P.P.; Nayak, A.K.; Vijayan, P.K.; Saha, D.; Sinha, R.K.

2011-01-01

Highlights: → We have highlighted the problem of drum level dynamics in a multiple loop type NC system using RELAP5 code. → The need of interconnections in steam and liquid spaces close to drum is established. → The steam space interconnections equalize pressure and liquid space interconnections equalize level. → With this scheme, the system can withstand anomalous conditions. → However, the controller is found to be inevitable for inventory balance. - Abstract: Advanced Heavy Water Reactor (AHWR) is a pressure tube type boiling water reactor employing natural circulation as the mode of heat removal under all the operating conditions. Main heat transport system (MHTS) of AHWR is essentially a multi-loop natural circulation system with all the loops connected to each other. Each loop of MHTS has a steam drum that provides for gravity based steam-water separation. Steam drum level is a very critical parameter especially in multi-loop natural circulation systems as large departures from the set point may lead to ineffective separation of steam-water or may affect the driving head. However, such a system is susceptible to steam drum level anomalies under postulated asymmetrical operating conditions among the different quadrants of the core like feedwater flow distribution anomaly among the steam drums or power anomaly among the core quadrants. Analyses were carried out to probe such scenarios and unravel the underlying dynamics of steam drum level using system code RELAP5/Mod3.2. In addition, a scheme to obviate such problem in a passive manner without dependence on level controller was examined. It was concluded that steam drums need to be connected in the liquid as well as steam space to make the system tolerant to asymmetrical operating conditions.

Inbreeding and it is effects on some productive and reproductive traits in a herd of Egyptian buffaloes

Directory of Open Access Journals (Sweden)

A.M. Kawthar

2010-02-01

Full Text Available A total of 1551 normal lactation records of Egyptian buffaloes, Kept at Mehallet Mousa Farm, belonging to Ministry of Agriculture, during the period from 1960 to 2001 were used. Milk yield, lactation period and age at first calving were studied in order to determine the presence of inbreeding in the herd and to evaluate it is effects as well as the effects of some environmental factors on these traits. In addition, genetic parameters of these traits are also studied. Milk yield, lactation period and age at first calving averaged 1193 ± 522 kg, 282±125 and 39 ± 3 mo, respectively. Among all three traits, only age at first calving was affected by inbreeding. Month of calving and year of calving had a significant effect on all traits studied, while age at first calving had no significant effect on milk yield and lactation period.

Impact of consanguineous marriages and degrees of inbreeding on fertility, child mortality, secondary sex ratio, selection intensity, and genetic load: a cross-sectional study from Northern India.

Science.gov (United States)

Fareed, Mohd; Kaisar Ahmad, Mir; Azeem Anwar, Malik; Afzal, Mohammad

2017-01-01

The aim of our study was to understand the relationship between consanguineous marriages and reproductive outcomes. A total of 999 families were recruited from five Muslim populations of Jammu region. Family pedigrees were drawn to access the family history and inbreeding status in terms of coefficient of inbreeding (F). Fertility, mortality, secondary sex ratio, selection intensity, and lethal equivalents were measured using standard methods. The significant differences for gross fertility was found to be higher among inbred groups as compared to the unrelated families (P consanguineous families of all populations in comparison with the non-consanguineous family groups. Moreover, the prenatal and postnatal child mortality rates (i.e., U5MR and U18MR) have presented a persuasive increase with an upsurge in the homozygosity level. The mortality rate was found to be maximum among families with the highest value of coefficient of inbreeding (F). The selection intensity (SI) also showed inflations among families with respect to their increasing inbreeding coefficients. The greater values of lethal equivalents per gamete (LEs/gamete) were observed for autosomal inheritance in comparison with sex-linked inheritance. Our conclusive assessment brings out the deleterious consequence of consanguineous marriages on reproductive outcomes.

Genome-scale data reveal that endemic Poecilia populations from small sulphidic springs display no evidence of inbreeding.

Science.gov (United States)

Brown, Anthony P; Greenway, Ryan; Morgan, Samuel; Quackenbush, Corey R; Giordani, Luca; Arias-Rodriguez, Lenin; Tobler, Michael; Kelley, Joanna L

2017-10-01

Populations with limited ranges can be highly vulnerable to changes in their environment and are, thus, of high conservation concern. Populations that experience human-induced range reductions are often highly inbred and lack genetic diversity, but it is unknown whether this is also the case for populations with naturally small ranges. The fishes Poecilia sulphuraria (listed as critically endangered) and Poecilia thermalis, which are endemic to small hydrogen sulphide-rich springs in southern Mexico, are examples of such populations with inherently small habitats. We used geometric morphometrics and population genetics to quantify phenotypic and genetic variation within and among two populations of P. sulphuraria and one population of P. thermalis. Principal component analyses revealed phenotypic and genetic differences among the populations. Evidence for inbreeding was low compared to populations that have undergone habitat reduction. The genetic data were also used to infer the demographic history of these populations to obtain estimates for effective population sizes and migration rates. Effective population sizes were large given the small habitats of these populations. Our results imply that these three endemic extremophile populations should each be considered separately for conservation purposes. Additionally, this study suggests that populations in naturally small habitats may have lower rates of inbreeding and higher genetic diversity than expected, and therefore may be better equipped to handle environmental perturbations than anticipated. We caution, however, that the inferred lack of inbreeding and the large effective population sizes could potentially be a result of colonization by genetically diverse ancestors. © 2017 John Wiley & Sons Ltd.

Free convection in a partially submerged fluid loop

International Nuclear Information System (INIS)

Britt, T.E.; Wood, D.C.

1982-01-01

Several natural convection loop systems are studied in order to determine the operational characteristics for a multiple loop container which is used to cool failed nuclear reactor assemblies. Both analytical and experimental studies were undertaken to examine flow in both circular and rectangular flow loops. It was found that when a circular loop is heated at the bottom and cooled at the top, recirculation cells form at all input power fluxes. At fluxes between 0.1 W/cm 2 and 0.7 W/cm 2 the cells caused flow oscillations and reversals. With the circular loop heated from the side, no recirculation cells were observed at the power fluxes up to 1.5 W/cm. Boiling did not occur in the circular loop. For a rectangular loop heated and cooled on its vertical sides, no recirculation cells or flow reversals were seen. At input power fluxes above 1.2 W/cm 2 , periodic boiling in the heated side caused flow oscillations

LOCA simulation tests in the RD-12 loop with multiple heat channels

International Nuclear Information System (INIS)

Ardron, K.H.; McGee, G.R.; Hawley, E.H.

1985-11-01

A series of tests has been performed in the RD-12 loop to study the bahaviour of a CANDU-type, primary heat transport system (PHTS) during the blowdown and injection phases of a loss-of-coolant accident (LOCA). Specifically, the tests were used to investigate flow stagnation and refilling of the core following a LOCA. RD-12 is a pressurized water loop with the basic geometry of a CANDU reactor PHTS, but at approximately 1/125 volume scale. The loop consists of U-tube steam generators, pumps, headers, feeders, and heated channels arranged in the symmetrical figure-of-eight configuration of the CANDU PHTS. In the LOCA simulation tests, the loop contained four horizontal heated channels, each containing a seven-element assembly of indirectly heated, fuel-rod simulators. The channels were nominally identical, and were arranged in parallel pairs between the headers in each half-circuit. Tests were carried out using various restricting orifices to represent pipe breaks of different sizes. The break sizes were specifically chosen such that stagnation conditions in the heated channels would be likely to occur. In some tests, the primary pumps were programmed to run down over a 100-s period to simulate a LOCA with simultaneous loss of pump power. Test results showed that, for certain break sizes, periods of low flow occurred in the channels in one half of the loop, leading to flow stratification and sheath temperature excursions. This report reviews the results of two of the tests, and discusses possible mechanisms that may have led to the low channel flow conditions observed in some cases. Plans for future experiments in the larger scale RD-14 facility are outlined. 5 refs

Nonequilibrium Chromosome Looping via Molecular Slip Links

Science.gov (United States)

Brackley, C. A.; Johnson, J.; Michieletto, D.; Morozov, A. N.; Nicodemi, M.; Cook, P. R.; Marenduzzo, D.

2017-09-01

We propose a model for the formation of chromatin loops based on the diffusive sliding of molecular slip links. These mimic the behavior of molecules like cohesin, which, along with the CTCF protein, stabilize loops which contribute to organizing the genome. By combining 3D Brownian dynamics simulations and 1D exactly solvable nonequilibrium models, we show that diffusive sliding is sufficient to account for the strong bias in favor of convergent CTCF-mediated chromosome loops observed experimentally. We also find that the diffusive motion of multiple slip links along chromatin is rectified by an intriguing ratchet effect that arises if slip links bind to the chromatin at a preferred "loading site." This emergent collective behavior favors the extrusion of loops which are much larger than the ones formed by single slip links.

Fitness consequences of outcrossing in a social spider with an inbreeding mating system.

Science.gov (United States)

Berger-Tal, Reut; Tuni, Cristina; Lubin, Yael; Smith, Deborah; Bilde, Trine

2014-02-01

Inbreeding mating systems are uncommon because of inbreeding depression. Mating among close relatives can evolve, however, when outcrossing is constrained. Social spiders show obligatory mating among siblings. In combination with a female-biased sex ratio, sib-mating results in small effective populations. In such a system, high genetic homozygosity is expected, and drift may cause population divergence. We tested the effect of outcrossing in the social spider Stegodyphus dumicola. Females were mated to sib-males, to a non-nestmate within the population, or to a male from a distant population, and fitness traits of F1s were compared. We found reduced hatching success of broods from between-population crosses, suggesting the presence of population divergence at a large geographical scale that may result in population incompatibility. However, a lack of a difference in offspring performance between inbred and outbred crosses indicates little genetic variation between populations, and could suggest recent colonization by a common ancestor. This is consistent with population dynamics of frequent colonizations by single sib-mated females of common origin, and extinctions of populations after few generations. Although drift or single mutations can lead to population divergence at a relatively short time scale, it is possible that dynamic population processes homogenize these effects at longer time scales. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

Reproductive Behavior and Inbreeding Depression in Endangered Eremostachys superba Royle ex Benth. (Labiatae in Dehra Dun Population, India

Directory of Open Access Journals (Sweden)

Arti Garg

2004-12-01

Full Text Available An assessment of reproductive behavior and inbreeding depression, if any, in critically endangered Eremostachys superba Royle ex Benth. (Labiatae was made to unveil the factors playing vital role in it’s reproductive biology and which may be responsible for the loss of fitness, viability and vigor of the species. Breeding experiments portrayed a failure of self-fertilization and a strong tendency towards out-breeding as seed set by xenogamy was highest (44.4%. However, the narrow restricted population of the type locality in Dehra Dun Siwaliks was just a ramet population sustained by clonal propagation of rhizomatous root stock, hence any out-crossing within these homozygous individuals also amounted to inbreeding. Further, there is no other population available within the range of normal seed dispersal mechanism or insect-pollinator-flight-range. The other populations reported are only from geographically distant region of Jammu and Kashmir state of India, which is too far a distance to be covered by the Nomia rustica West. and Ceratina heiroglyphica Sm., the oligophilic pollinators of E. superba, hence any crossing taking place also amounts to selfing in strict sense. Chances of induction of genetic variation by crossing between two different populations are remote. This was also supported by the data of seed production and germination experiments. Even the healthy seeds suffered from loss of fitness and failed to germinate under natural conditions. This strongly indicated prevalence of inbreeding depression and loss of fitness of the progeny right from the stage of germination, a phenomenon hazardous for sustenance and perpetuation of species leading to rarity.

Coupling between feedback loops in autoregulatory networks affects bistability range, open-loop gain and switching times

International Nuclear Information System (INIS)

Tiwari, Abhinav; Igoshin, Oleg A

2012-01-01

Biochemical regulatory networks governing diverse cellular processes such as stress-response, differentiation and cell cycle often contain coupled feedback loops. We aim at understanding how features of feedback architecture, such as the number of loops, the sign of the loops and the type of their coupling, affect network dynamical performance. Specifically, we investigate how bistability range, maximum open-loop gain and switching times of a network with transcriptional positive feedback are affected by additive or multiplicative coupling with another positive- or negative-feedback loop. We show that a network's bistability range is positively correlated with its maximum open-loop gain and that both quantities depend on the sign of the feedback loops and the type of feedback coupling. Moreover, we find that the addition of positive feedback could decrease the bistability range if we control the basal level in the signal-response curves of the two systems. Furthermore, the addition of negative feedback has the capacity to increase the bistability range if its dissociation constant is much lower than that of the positive feedback. We also find that the addition of a positive feedback to a bistable network increases the robustness of its bistability range, whereas the addition of a negative feedback decreases it. Finally, we show that the switching time for a transition from a high to a low steady state increases with the effective fold change in gene regulation. In summary, we show that the effect of coupled feedback loops on the bistability range and switching times depends on the underlying mechanistic details. (paper)

LoopIng: a template-based tool for predicting the structure of protein loops.

KAUST Repository

Messih, Mario Abdel

2015-08-06

Predicting the structure of protein loops is very challenging, mainly because they are not necessarily subject to strong evolutionary pressure. This implies that, unlike the rest of the protein, standard homology modeling techniques are not very effective in modeling their structure. However, loops are often involved in protein function, hence inferring their structure is important for predicting protein structure as well as function.We describe a method, LoopIng, based on the Random Forest automated learning technique, which, given a target loop, selects a structural template for it from a database of loop candidates. Compared to the most recently available methods, LoopIng is able to achieve similar accuracy for short loops (4-10 residues) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has the advantage of being very fast (on average: 1 min/loop).www.biocomputing.it/loopinganna.tramontano@uniroma1.itSupplementary data are available at Bioinformatics online.

On-the-fly reduction of open loops

Energy Technology Data Exchange (ETDEWEB)

Buccioni, Federico; Pozzorini, Stefano; Zoller, Max [Universitaet Zuerich, Physik-Institut, Zurich (Switzerland)

2018-01-15

Building on the open-loop algorithm we introduce a new method for the automated construction of one-loop amplitudes and their reduction to scalar integrals. The key idea is that the factorisation of one-loop integrands in a product of loop segments makes it possible to perform various operations on-the-fly while constructing the integrand. Reducing the integrand on-the-fly, after each segment multiplication, the construction of loop diagrams and their reduction are unified in a single numerical recursion. In this way we entirely avoid objects with high tensor rank, thereby reducing the complexity of the calculations in a drastic way. Thanks to the on-the-fly approach, which is applied also to helicity summation and for the merging of different diagrams, the speed of the original open-loop algorithm can be further augmented in a very significant way. Moreover, addressing spurious singularities of the employed reduction identities by means of simple expansions in rank-two Gram determinants, we achieve a remarkably high level of numerical stability. These features of the new algorithm, which will be made publicly available in a forthcoming release of the OpenLoops program, are particularly attractive for NLO multi-leg and NNLO real-virtual calculations. (orig.)

On-the-fly reduction of open loops

Science.gov (United States)

Buccioni, Federico; Pozzorini, Stefano; Zoller, Max

2018-01-01

Building on the open-loop algorithm we introduce a new method for the automated construction of one-loop amplitudes and their reduction to scalar integrals. The key idea is that the factorisation of one-loop integrands in a product of loop segments makes it possible to perform various operations on-the-fly while constructing the integrand. Reducing the integrand on-the-fly, after each segment multiplication, the construction of loop diagrams and their reduction are unified in a single numerical recursion. In this way we entirely avoid objects with high tensor rank, thereby reducing the complexity of the calculations in a drastic way. Thanks to the on-the-fly approach, which is applied also to helicity summation and for the merging of different diagrams, the speed of the original open-loop algorithm can be further augmented in a very significant way. Moreover, addressing spurious singularities of the employed reduction identities by means of simple expansions in rank-two Gram determinants, we achieve a remarkably high level of numerical stability. These features of the new algorithm, which will be made publicly available in a forthcoming release of the OpenLoops program, are particularly attractive for NLO multi-leg and NNLO real-virtual calculations.

Heterotic studies and inbreeding depression in f/sub 2/populations of upland cotton

International Nuclear Information System (INIS)

Panni, M.K.

2012-01-01

To study the genetic potential, heterotic effects and inbreeding depression, 8 X 8 F/sub 2/diallel populations with parental lines of upland cotton were grown during crop season 2010 in a randomized complete block design at Khyber Pakhtunkhwa Agricultural University Peshawar, Pakistan. Highly significant ( p = 0.01 ) variations were noticed among parental lines and F/sub 2/ populations for all the traits. According to genotypes mean performance for various traits, plant height varied from 101.60 to 126.30 cm and 98.60 to 140.60 cm, bolls plant/sup -1/ (12.87 to 19.53; 12.13 to 22.60), boll weight (3.80 to 5.01 g; 3.04 to 5.38 g) and seed cotton yield plant/sup -1/ varied from 55.74 to 85.47 g and 45.57 to 96.05 g in parental cultivars and their F/sub 2/ populations, respectively. However, 12 and 7 F/sub 2/ populations manifested significant heterosis over mid and better parents for plant height, 7 and 3 for bolls plant/sup -1/, 13 and 9 for boll weight and 13 and 5 F/sub 2/ populations for seed cotton yield plant/sup -1/, respectively. F/sub 2/ populations i.e. CIM-554 X CIM-473, CIM-554 X CIM-499, CIM-496 X SLH-284, CIM-473 X CIM-446 and CIM-554 X SLH-284 with low mean values for plant height performed better and manifested highly significant heterotic values over mid and better parents for bolls per plant, boll weight and seed cotton yield. By comparing F/sub 2/ mean values with F/sub 1/s, inbreeding depression was observed for plant height (0.66 to 23. 99%), bolls per plant (5.00 to 63.16%), boll weight (0.20 to 23.24%) and seed cotton yield (0.44 to 75.52%). However, 62% of F/sub 2/ populations revealed negative values for inbreeding depression, 14% for bolls per plant, 77% for boll weight and 21% for yield, revealed that these F/sub 2/ populations were more stable and performed better than F/sub 1/s even after segregation. Although, F/sub 2/ populations may display less heterosis as compared to F/sub 1/, but still better than high parents and can be used as

Power Hardware-in-the-Loop Testing of Multiple Photovoltaic Inverters' Volt-Var Control with Real-Time Grid Model

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Sudipta; Nelson, Austin; Hoke, Anderson

2016-12-12

Traditional testing methods fall short in evaluating interactions between multiple smart inverters providing advanced grid support functions due to the fact that such interactions largely depend on their placements on the electric distribution systems with impedances between them. Even though significant concerns have been raised by the utilities on the effects of such interactions, little effort has been made to evaluate them. In this paper, power hardware-in-the-loop (PHIL) based testing was utilized to evaluate autonomous volt-var operations of multiple smart photovoltaic (PV) inverters connected to a simple distribution feeder model. The results provided in this paper show that depending on volt-var control (VVC) parameters and grid parameters, interaction between inverters and between the inverter and the grid is possible in some extreme cases with very high VVC slopes, fast response times and large VVC response delays.

Non-commutative flux representation for loop quantum gravity

Science.gov (United States)

Baratin, A.; Dittrich, B.; Oriti, D.; Tambornino, J.

2011-09-01

The Hilbert space of loop quantum gravity is usually described in terms of cylindrical functionals of the gauge connection, the electric fluxes acting as non-commuting derivation operators. It has long been believed that this non-commutativity prevents a dual flux (or triad) representation of loop quantum gravity to exist. We show here, instead, that such a representation can be explicitly defined, by means of a non-commutative Fourier transform defined on the loop gravity state space. In this dual representation, flux operators act by sstarf-multiplication and holonomy operators act by translation. We describe the gauge invariant dual states and discuss their geometrical meaning. Finally, we apply the construction to the simpler case of a U(1) gauge group and compare the resulting flux representation with the triad representation used in loop quantum cosmology.

THE CORONAL LOOP INVENTORY PROJECT: EXPANDED ANALYSIS AND RESULTS

Energy Technology Data Exchange (ETDEWEB)

Schmelz, J. T. [USRA, 7178 Columbia Gateway Drive, Columbia, MD 21046 (United States); Christian, G. M.; Chastain, R. A., E-mail: jschmelz@usra.edu [Physics Department, University of Memphis, Memphis, TN 38152 (United States)

2016-11-10

We have expanded upon earlier work that investigates the relative importance of coronal loops with isothermal versus multithermal cross-field temperature distributions. These results are important for determining if loops have substructure in the form of unresolved magnetic strands. We have increased the number of loops targeted for temperature analysis from 19 to 207 with the addition of 188 new loops from multiple regions. We selected all loop segments visible in the 171 Å images of the Atmospheric Imaging Assembly (AIA) that had a clean background. Eighty-six of the new loops were rejected because they could not be reliably separated from the background in other AIA filters. Sixty-one loops required multithermal models to reproduce the observations. Twenty-eight loops were effectively isothermal, that is, the plasma emission to which AIA is sensitive could not be distinguished from isothermal emission, within uncertainties. Ten loops were isothermal. Also, part of our inventory was one small flaring loop, one very cool loop whose temperature distribution could not be constrained by the AIA data, and one loop with inconclusive results. Our survey can confirm an unexpected result from the pilot study: we found no isothermal loop segments where we could properly use the 171-to-193 ratio method, which would be similar to the analysis done for many loops observed with TRACE and EIT. We recommend caution to observers who assume the loop plasma is isothermal, and hope that these results will influence the direction of coronal heating models and the effort modelers spend on various heating scenarios.

Sex linked versus autosomal inbreeding coefficient in close consanguineous marriages in the Basque country and Castile (Spain): genetic implications.

Science.gov (United States)

Calderón, R; Morales, B; Peña, J A; Delgado, J

1995-10-01

Pedigree structures of 161 uncle/niece-aunt/nephew and 4420 first cousin consanguineous marriages registered during the 19th and 20th centuries in two large and very different Spanish regions have been analysed and their genetic consequences evaluated. The frequencies of the different pedigree subtypes within each degree of relationship were quite similar in both populations despite significant heterogeneity in inbreeding patterns. The mean X-linked inbreeding coefficient (Fx) for each type of cousin mating was calculated and compared to that expected for autosomal genes (F). The effect of genealogical structure on the Fx/F ratio was compared to different cultural populations worldwide. Preferentiality and avoidance of close consanguinity along with specific types of pedigrees are discussed on the basis of premarital migration and sociocultural rules still deeply rooted in certain human groups. By admitting that the observed Fx coefficient is usually higher than F in most human populations some remarks have been made in terms of population genetic risk.

Integrated Vehicle Thermal Management - Combining Fluid Loops in Electric Drive Vehicles (Presentation)

Energy Technology Data Exchange (ETDEWEB)

Rugh, J. P.

2013-07-01

Plug-in hybrid electric vehicles and electric vehicles have increased vehicle thermal management complexity, using separate coolant loop for advanced power electronics and electric motors. Additional thermal components result in higher costs. Multiple cooling loops lead to reduced range due to increased weight. Energy is required to meet thermal requirements. This presentation for the 2013 Annual Merit Review discusses integrated vehicle thermal management by combining fluid loops in electric drive vehicles.

Creating integral value for stakeholders in closed loop supply chains

NARCIS (Netherlands)

Schenkel, Maren; Krikke, Harold; Caniëls, Marjolein CJ; van der Laan, Erwin

This paper contributes to the existing literature by researching integral value creation in closed loop supply chains (CLSCs). We distinguish between multiple types of business value, strategic success factors, and multiple groups of stakeholders that affect and are affected by CLSC activities. To

Evidence of high inbreeding in a population of the endangered giant anteater, Myrmecophaga tridactyla (Myrmecophagidae, from Emas National Park, Brazil

Directory of Open Access Journals (Sweden)

Rosane G. Collevatti

2007-01-01

Full Text Available We report the genetic structure, relatedness and mating structure of a population of the endangered giant anteater Myrmecophaga tridactyla Linnaeus, 1758 in the Emas National Park, Brazil, based on variability at five microsatellite loci. Additionally, we addressed the hypothesis that the M. tridactyla population studied has low levels of polymorphism and high levels of inbreeding and relatedness and that animals with overlapping home range are highly related. All five microsatellite loci displayed low levels of polymorphism and of expected and observed heterozygosity. The low level of polymorphism and high inbreeding showed by the population studied may be the outcome of high mortality and reduction in population size due to recurrent fire events in the Emas National Park, as reported in 1994. The reduction in population size may have led to a higher frequency of mating between closely related animals, augmented by the isolation of the population in the park because of the expansion of agricultural land and fragmentation of the Cerrado environment. The natural history of M. tridactyla and the phylopatric (sex-biased dispersal behavior of females should increase the effects of isolation and bottlenecking, decreasing gene flow and increasing inbreeding. However, the low levels of polymorphism found in this population may simply be due to the natural history and evolution of M. tridactyla as reported for other species. The genetic structure and dynamics of this population needs to be investigated more profoundly in order to provide sound data for the design of conservation strategies for M. tridactyla in the Emas National Park.

On the duality-transformed Wilson loop operator

International Nuclear Information System (INIS)

Mizrachi, L.

1981-08-01

Duality transformation of the vacuum expectation value of the Wilson loop operator is performed in the radial gauge (xsub(μ)Asub(μ)sup(a)(x) = 0). It is found to be equal, up to a multiplicative constant, to , where O(c) is a line integral along the loop c (defining the Wilson loop operator) of a function of the dual field variables. In the weak coupling region self duality is recovered in the sense that the Lagrangian is local gauge invariant defined in terms of the dual gauge potentials but with g (the coupling constant) replaced by 1/g, and O(c) is simply the line integral of the dual gauge potentials. For large g, a strong coupling expansion is suggested (but the theory is not local gauge invariant). (author)

Loop Transfer Matrix and Loop Quantum Mechanics

International Nuclear Information System (INIS)

Savvidy, George K.

2000-01-01

The gonihedric model of random surfaces on a 3d Euclidean lattice has equivalent representation in terms of transfer matrix K(Q i ,Q f ), which describes the propagation of loops Q. We extend the previous construction of the loop transfer matrix to the case of nonzero self-intersection coupling constant κ. We introduce the loop generalization of Fourier transformation which allows to diagonalize transfer matrices, that depend on symmetric difference of loops only and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out the analogy with quantum mechanics of point particles, to introduce conjugate loop momentum P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using the generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. In particular the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops and is equal to the free energy of 2d Ising model. (author)

Lowered Diversity and Increased Inbreeding Depression within Peripheral Populations of Wild Rice Oryza rufipogon.

Science.gov (United States)

Gao, Li-Zhi; Gao, Cheng-Wen

2016-01-01

The distribution of genetic variability from the interior towards the periphery of a species' range is of great interest to evolutionary biologists. Although it has been long presumed that population genetic variation should decrease as a species' range is approached, results of empirical investigations still remain ambiguous. Knowledge regarding patterns of genetic variability as well as affected factors is particularly not conclusive in plants. To determine genetic divergence in peripheral populations of the wild rice Oryza rufipogon Griff. from China, genetic diversity and population structure were studied in five northern & northeastern peripheral and 16 central populations using six microsatellite loci. We found that populations resided at peripheries of the species possessed markedly decreased microsatellite diversity than those located in its center. Population size was observed to be positively correlated with microsatellite diversity. Moreover, there are significantly positive correlations between levels of microsatellite diversity and distances from the northern and northeastern periphery of this species. To investigate genetic structure and heterozygosity variation between generations of O. rufipogon, a total of 2382 progeny seeds from 186 maternal families were further assayed from three peripheral and central populations, respectively. Peripheral populations exhibited significantly lower levels of heterozygosities than central populations for both seed and maternal generations. In comparisons with maternal samples, significantly low observed heterozygosity (HO) and high heterozygote deficit within populations (FIS) values were detected in seed samples from both peripheral and central populations. Significantly lower observed heterozygosity (HO) and higher FIS values were further observed in peripheral populations than those in central populations for seed samples. The results indicate an excess of homozygotes and thus high inbreeding depression in

Multiple-Ring Digital Communication Network

Science.gov (United States)

Kirkham, Harold

1992-01-01

Optical-fiber digital communication network to support data-acquisition and control functions of electric-power-distribution networks. Optical-fiber links of communication network follow power-distribution routes. Since fiber crosses open power switches, communication network includes multiple interconnected loops with occasional spurs. At each intersection node is needed. Nodes of communication network include power-distribution substations and power-controlling units. In addition to serving data acquisition and control functions, each node acts as repeater, passing on messages to next node(s). Multiple-ring communication network operates on new AbNET protocol and features fiber-optic communication.

A Culture-Behavior-Brain Loop Model of Human Development.

Science.gov (United States)

Han, Shihui; Ma, Yina

2015-11-01

Increasing evidence suggests that cultural influences on brain activity are associated with multiple cognitive and affective processes. These findings prompt an integrative framework to account for dynamic interactions between culture, behavior, and the brain. We put forward a culture-behavior-brain (CBB) loop model of human development that proposes that culture shapes the brain by contextualizing behavior, and the brain fits and modifies culture via behavioral influences. Genes provide a fundamental basis for, and interact with, the CBB loop at both individual and population levels. The CBB loop model advances our understanding of the dynamic relationships between culture, behavior, and the brain, which are crucial for human phylogeny and ontogeny. Future brain changes due to cultural influences are discussed based on the CBB loop model. Copyright © 2015 Elsevier Ltd. All rights reserved.

Correlation between incidences of self-inflicted burns and means of inbreeding coefficients, an ecologic study.

Science.gov (United States)

Saadat, Mostafa; Zendeh-Boodi, Zahra

2006-09-01

The aim of the study is to obtain more insight into the possible association between consanguinity and the incidence of deliberate self-burning. Data were obtained by analysis of medical records of patients hospitalized in two referral burn centers: Chormy Burn Center (Bushehr Province, south of Iran) from March 21, 1998, through March 20, 2004, and Shahid Sadoqi Center of Burns and Injuries (Yazd Province, center of Iran) from March 21, 2000, through March 20, 2004. The incidence of suicidal burns was 6.51 and 2.32/100,000 person-years for Bushehr and Yazd Provinces, respectively. The observed sex ratio of patients in both centers indicated there was a female predominance in patients with self-inflicted burns. Using patients' home addresses, patients were sorted into 16 cities. The incidence of suicide by self-burning ranged from 0.80 (for Tabas, located in Yazd Province) to 12.60/100,000 person-years (for Dilam, located in Bushehr Province). The coefficient of inbreeding defines the probability that an individual received both alleles of a pair from an identical ancestral source. There was a significant correlation between incidences of suicidal burns and mean coefficient of inbreeding (r = 0.782, df = 14, p < 0.001). In addition to other factors, consanguineous marriage may be a risk factor that influences the incidence of suicidal burns in a population.

R-loops: targets for nuclease cleavage and repeat instability.

Science.gov (United States)

Freudenreich, Catherine H

2018-01-11

R-loops form when transcribed RNA remains bound to its DNA template to form a stable RNA:DNA hybrid. Stable R-loops form when the RNA is purine-rich, and are further stabilized by DNA secondary structures on the non-template strand. Interestingly, many expandable and disease-causing repeat sequences form stable R-loops, and R-loops can contribute to repeat instability. Repeat expansions are responsible for multiple neurodegenerative diseases, including Huntington's disease, myotonic dystrophy, and several types of ataxias. Recently, it was found that R-loops at an expanded CAG/CTG repeat tract cause DNA breaks as well as repeat instability (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Two factors were identified as causing R-loop-dependent breaks at CAG/CTG tracts: deamination of cytosines and the MutLγ (Mlh1-Mlh3) endonuclease, defining two new mechanisms for how R-loops can generate DNA breaks (Su and Freudenreich, Proc Natl Acad Sci USA 114, E8392-E8401, 2017). Following R-loop-dependent nicking, base excision repair resulted in repeat instability. These results have implications for human repeat expansion diseases and provide a paradigm for how RNA:DNA hybrids can cause genome instability at structure-forming DNA sequences. This perspective summarizes mechanisms of R-loop-induced fragility at G-rich repeats and new links between DNA breaks and repeat instability.

Monodromy relations in higher-loop string amplitudes

Directory of Open Access Journals (Sweden)

S. Hohenegger

2017-12-01

Full Text Available New monodromy relations of loop amplitudes are derived in open string theory. We particularly study N-point (planar and non-planar one-loop amplitudes described by a world-sheet cylinder and derive a set of relations between subamplitudes of different color orderings. Various consistency checks are performed by matching α′-expansions of planar and non-planar amplitudes involving elliptic iterated integrals with the resulting periods giving rise to two sets of multiple elliptic zeta values. The latter refer to the two homology cycles on the once-punctured complex elliptic curve and the monodromy equations provide relations between these two sets of multiple elliptic zeta values. Furthermore, our monodromy relations involve new objects for which we present a tentative interpretation in terms of open string scattering amplitudes in the presence of a non-trivial gauge field flux. Finally, we provide an outlook on how to generalize the new monodromy relations to the non-oriented case and beyond the one-loop level. Comparing a subset of our results with recent findings in the literature we find therein several serious issues related to the structure and significance of monodromy phases and the relevance of missed contributions from contour integrations.

Extinction of mammalian populations in conservation units of the Brazilian Cerrado by inbreeding depression in stochastic environments

OpenAIRE

Silva, Marcel Müller Fernandes Pereira da; Diniz-Filho, José Alexandre Felizola

2008-01-01

Despite methodological and theoretical advances in conservation genetics, data on genetic variation on broad regional spatial scales are still scarce, leading conservation planners to use general heuristic or simulation models for an integrated analysis of genetic, demographic and landscape parameters. Here, we extended previous results by evaluating spatial patterns of extinction by inbreeding depression under stochastic variation of environments for mammalian populations in 31 conservation ...

Basal and induced granulopoiesis in outbred, F1 hybrid and inbred mice: can inbreeding depression influence the experimental practice?

Czech Academy of Sciences Publication Activity Database

Hofer, Michal; Pospíšil, Milan; Dušek, L.; Holá, Jiřina; Hoferová, Zuzana; Weiterová, Lenka

2010-01-01

Roč. 235, č. 8 (2010), s. 928-931 ISSN 1535-3702 R&D Projects: GA ČR(CZ) GA305/08/0158 Institutional research plan: CEZ:AV0Z50040507; CEZ:AV0Z50040702 Keywords : hematopoiesis * outbred mice * inbreeding depression Subject RIV: BO - Biophysics Impact factor: 2.954, year: 2010

Exact one-fermion-loop contributions in (1+1)-dimensional solitons

International Nuclear Information System (INIS)

Shepard, J.R.; Price, C.E.; Ferree, T.C.

1993-01-01

We find solutions to the (1+1)-dimensional scalar-only linear σ model. A new method is used to compute one-fermion-loop contributions exactly, and agreemment with published results employing other methods is excellent. A renormalization scheme which differs from that commonly used in such calculations but is similar to that required in 1+3 dimensions is also presented. We compare ''kink'' versus ''shallow bag'' solutions, paying careful attention to the implications of the one-fermion-loop contributions for the stability of the former. We find that, for small fermion multiplicities, self-consistent shallow bag solutions are always more bound than their metastable kink counterparts. However, as the fermion multiplicity increases, shallow bags evolve into kinks which eventually are the only self-consistent configurations. This situation is qualitatively the same for the two renormalization schemes considered. When we construct ''baryons,'' each containing three fermions, the kink configuration is typically more bound than the shallow bag when one-fermion-loop contributions are included

Reproductive Success and Inbreeding Differ in Fragmented Populations of Pinus rzedowskii and Pinus ayacahuite var. veitchii, Two Endemic Mexican Pines under Threat

Directory of Open Access Journals (Sweden)

Paty Castilleja Sánchez

2016-08-01

Full Text Available Seed production, quality, germination and seedling establishment are indicators of reproductive success in conifers. Monitoring of these parameters is essential to determine the viability of populations for the purposes of conservation. We analyze cone and seed traits as indicators of reproductive success in the endangered Rzedowski´s pine (Pinus rzedowskii (Madrigal et Caballero and near-threatened veitchii pine (Pinus ayacahuite var. veitchii (Shaw in west-central Michoacán, Mexico. These traits were systematically quantified and their variation assessed using Generalized Linear Mixed Models (GLMMs. We found that the reproductive success of Rzedowski’s pine seems to be critical, presenting low seed efficiency (17.10%, germination (5.0% and seedling establishment (27.7%, with high levels of inbreeding (0.79. In contrast, veitchii pine presents moderate seed efficiency (54.9%, high germination (71.5% and seedling establishment (84%–97% and low inbreeding (0.33. Reproductive indicators differed significantly among zones and populations for each species, where fragment sizes mainly affected seed production and efficiency. This result indicates that fragmentation has played a more important role in the reproductive success of Rzedowski’s pine than in veitchii pine, perhaps by limiting pollen flow among zones and populations and producing higher levels of inbreeding and lower seed efficiency in the former species. We propose a conservation strategy for these important pine species in order to increase their long-term genetic viability.

Strong inbreeding depression and individually variable mating system in the narrow endemic Erodium cazorlanum (Geraniaceae

Directory of Open Access Journals (Sweden)

Alonso, Conchita

2013-06-01

Full Text Available Angiosperms evolved different systems to attract effective pollinators while reducing selfing in hermaphroditic flowers. Selfing ability can be advantageous when pollinators and/or mates are scarce, although inbreeding depression may largely reduce those advantages. Recent comparative analyses suggested endemic species tend to evolve self-compatibility but a better understanding of the associated reproductive and genetic tradeoffs is required. Experimental hand-pollinations under greenhouse conditions were conducted to investigate the selfing ability and estimate inbreeding depression up to the offspring’ first reproductive event in Ero dium cazorlanum, a narrow endemic species restricted to dolomite outcrops in SE Spanish mountains. We found autonomous selfing ineffective. Further, when experimentally applied, pollen of the same flower produced significantly fewer fruits and seeds compared to geitonogamous and cross pollinations. The number of seeds per fruit was significantly higher after cross pollinations and strong inbreeding depression accumulated through the life-cycle. Interestingly, individual plants exhibited broad variation in selfing ability with six out of 14 individuals producing no seed after geitonogamy. Understanding the consequences of individual variation in self compatibility deserves further investigation in the field now that we know that strong inbreeding depression may limit recruitment of selfed progeny.Las Angiospermas han desarrollado diversos sistemas para atraer polinizadores eficientes y al mismo tiempo reducir la posibilidad de autopolinización asociada al hermafroditismo. La capacidad de autopolinización puede ser ventajosa en situaciones de escasez de polinizadores y/o individuos reproductores, beneficios que pueden reducirse ampliamente a causa de la depresión por endogamia. Análisis filogenéticos recientes indicaron que las especies endémicas tienden a presentar sistemas de autocompatibilidad, por tanto

Extinction of canid populations by inbreeding depression under stochastic environments in Southwestern Goiás State: a simulation study

Directory of Open Access Journals (Sweden)

Flávia Melo Rodrigues

2007-01-01

Full Text Available A frequently addressed question in conservation biology is what is the chance of survival for a population for a given number of years under certain conditions of habitat loss and human activities. This can be estimated through an integrated analysis of genetic, demographic and landscape processes, which allows the prediction of more realistic and precise models of population persistence. In this study, we modeled extinction in stochastic environments under inbreeding depression for two canid species, the maned wolf (Chrysocyon brachiurus and the crab-eating fox (Cerdocyon thous, in southwest Goiás State. Genetic parameters were obtained from six microsattelite loci (Short Tandem Repeats - STR, which allowed estimates of inbreeding levels and of the effective population size under a stepwise mutation model based on heterozygosis. The simulations included twelve alternative scenarios with varying rates of habitat loss, magnitude of population fluctuation and initial inbreeding levels. ANOVA analyses of the simulation results showed that times to extinction were better explained by demographic parameters. Times to extinction ranged from 352 to 844, in the worst and best scenario, respectively, for the large-bodied maned wolf. For the small-bodied crab-eating fox, these same estimates were 422 and 974 years. Simulations results are within the expectation based on knowledge about species' life history, genetics and demography. They suggest that populations can persist through a reasonable time (i.e., more than 200 years even under the worst demographic scenario. Our analyses are a starting point for a more focused evaluation of persistence in these populations. Our results can be used in future research aiming at obtaining better estimates of parameters that may, in turn, be used to achieve more appropriate and realist population viability models at a regional scale.

Growth and instability of charged dislocation loops under irradiation in ceramic materials

CERN Document Server

Ryazanov, A I; Kinoshita, C; Klaptsov, A V

2002-01-01

We have investigated the physical mechanisms of the growth and stability of charged dislocation loops in ceramic materials with very strong different mass of atoms (stabilized cubic zirconia) under different energies and types of irradiation conditions: 100-1000 keV electrons, 100 keV He sup + and 300 keV O sup + ions. The anomalous formation of extended defect clusters (charged dislocation loops) has been observed by TEM under electron irradiation subsequent to ion irradiation. It is demonstrated that very strong strain field (contrast) near charged dislocation loops is formed. The dislocation loops grow up to a critical size and after then become unstable. The instability of the charged dislocation loop leads to the multiplication of dislocation loops and the formation of dislocation network near the charged dislocation loops. A theoretical model is suggested for the explanation of the growth and stability of the charged dislocation loop, taking the charge state of point defects. The calculated distribution...

Voice loops as coordination aids in space shuttle mission control.

Science.gov (United States)

Patterson, E S; Watts-Perotti, J; Woods, D D

1999-01-01

Voice loops, an auditory groupware technology, are essential coordination support tools for experienced practitioners in domains such as air traffic management, aircraft carrier operations and space shuttle mission control. They support synchronous communication on multiple channels among groups of people who are spatially distributed. In this paper, we suggest reasons for why the voice loop system is a successful medium for supporting coordination in space shuttle mission control based on over 130 hours of direct observation. Voice loops allow practitioners to listen in on relevant communications without disrupting their own activities or the activities of others. In addition, the voice loop system is structured around the mission control organization, and therefore directly supports the demands of the domain. By understanding how voice loops meet the particular demands of the mission control environment, insight can be gained for the design of groupware tools to support cooperative activity in other event-driven domains.

Loop kinematics

International Nuclear Information System (INIS)

Migdal, A.A.

1982-01-01

Basic operators acting in the loop space are introduced. The topology of this space and properties of the Stokes type loop functionals are discussed. The parametrically invariant loop calculus developed here is used in the loop dynamics

Transition pathways in the unfaulting of dislocation loops

International Nuclear Information System (INIS)

Kubota, Alison; Wolfer, W.G.

2005-01-01

In order to study the dynamic mechanism of loop unfaulting, we performed large-scale classical molecular dynamics simulations involving computational cells with several millions of atoms. To induce dislocation loop unfaulting, we launched 1 ps duration traction stress pulses at a free surface of the computational box. In many cases, we observe unfaulting to involve both intuitive and complex dislocation processes with multiple Shockley partial dislocations. However, in some instances, we observe unfaulting to occur by a sudden instability of the stacking fault without clear traces of dislocation reactions

Deepening Our Understanding of Academic Inbreeding Effects on Research Information Exchange and Scientific Output: New Insights for Academic Based Research

Science.gov (United States)

Horta, Hugo

2013-01-01

This paper analyzes the impact of academic inbreeding in relation to academic research, and proposes a new conceptual framework for its analysis. We find that mobility (or lack of) at the early research career stage is decisive in influencing academic behaviors and scientific productivity. Less mobile academics have more inward oriented…

Investigation of Inner Loop Flight Control Strategies for High-Speed Research

Science.gov (United States)

Newman, Brett; Kassem, Ayman

1999-01-01

This report describes the activities and findings conducted under contract NAS1-19858 with NASA Langley Research Center. Subject matter is the investigation of suitable flight control design methodologies and solutions for large, flexible high-speed vehicles. Specifically, methodologies are to address the inner control loops used for stabilization and augmentation of a highly coupled airframe system possibly involving rigid-body motion, structural vibrations, unsteady aerodynamics, and actuator dynamics. Techniques considered in this body of work are primarily conventional-based, and the vehicle of interest is the High-Speed Civil Transport (HSCT). Major findings include 1) current aeroelastic vehicle modeling procedures require further emphasis and refinement, 2) traditional and nontraditional inner loop flight control strategies employing a single feedback loop do not appear sufficient for highly flexible HSCT class vehicles, 3) inner loop flight control systems will, in all likelihood, require multiple interacting feedback loops, and 4) Ref. H HSCT configuration presents major challenges to designing acceptable closed-loop flight dynamics.

Mating animals by minimising the covariance between ancestral contributions generates less inbreeding without compromising genetic gain in breeding schemes with truncation selection

DEFF Research Database (Denmark)

Henryon, M; Berg, P; Sørensen, A C

2009-01-01

We reasoned that mating animals by minimising the covariance between ancestral contributions (MCAC mating) will generate less inbreeding and at least as much genetic gain as minimum-coancestry mating in breeding schemes where the animals are truncation-selected. We tested this hypothesis by stoch...

The two-loop master integrals for qq-bar→VV

International Nuclear Information System (INIS)

Gehrmann, Thomas; Manteuffel, Andreas von; Tancredi, Lorenzo; Weihs, Erich

2014-01-01

We compute the full set of two-loop Feynman integrals appearing in massless two-loop four-point functions with two off-shell legs with the same invariant mass. These integrals allow to determine the two-loop corrections to the amplitudes for vector boson pair production at hadron colliders, qq-bar→VV, and thus to compute this process to next-to-next-to-leading order accuracy in QCD. The master integrals are derived using the method of differential equations, employing a canonical basis for the integrals. We obtain analytical results for all integrals, expressed in terms of multiple polylogarithms. We optimize our results for numerical evaluation by employing functions which are real valued for physical scattering kinematics and allow for an immediate power series expansion

Alternative loop rings

CERN Document Server

Goodaire, EG; Polcino Milies, C

1996-01-01

For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

Web-based ground loop supervision system for the TJ-II Stellarator

International Nuclear Information System (INIS)

Pena, A. de la; Lapayese, F.; Pacios, L.; Carrasco, R.

2005-01-01

To minimize electromagnetic interferences in diagnostic and control signals, and to guarantee safe operation of TJ-II, ground loops must be avoided. In order to meet this goal, the whole grounding system of the TJ-II was split into multiple single branches that are connected at a single earth point located near the TJ-II structure in the torus hall. A real-time ground loop supervision system (GLSS) has been designed, manufactured and tested by the TJ-II control group for detecting unintentional short circuits between isolated grounded parts. A web server running on the real-time operating system OS-9 provides remote access to the real-time ground loops measurement. Ground loops monitoring and different operation modes can be configured via any web browser. This paper gives the detailed design of the whole TJ-II ground loop supervision system and its results during its operation

Web-based ground loop supervision system for the TJ-II Stellarator

Energy Technology Data Exchange (ETDEWEB)

Pena, A. de la [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain)]. E-mail: a.delapena@ciemat.es; Lapayese, F. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain); Pacios, L. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain); Carrasco, R. [Asociacion EURATOM-CIEMAT Para Fusion, Avd. Complutense 22, 28040 Madrid (Spain)

2005-11-15

To minimize electromagnetic interferences in diagnostic and control signals, and to guarantee safe operation of TJ-II, ground loops must be avoided. In order to meet this goal, the whole grounding system of the TJ-II was split into multiple single branches that are connected at a single earth point located near the TJ-II structure in the torus hall. A real-time ground loop supervision system (GLSS) has been designed, manufactured and tested by the TJ-II control group for detecting unintentional short circuits between isolated grounded parts. A web server running on the real-time operating system OS-9 provides remote access to the real-time ground loops measurement. Ground loops monitoring and different operation modes can be configured via any web browser. This paper gives the detailed design of the whole TJ-II ground loop supervision system and its results during its operation.

Inbreeding trends and pedigree analysis of Bavarian mountain hounds, Hanoverian hounds and Tyrolean hounds.

Science.gov (United States)

Voges, S; Distl, O

2009-10-01

The objective of this study was to analyse genetic diversity for the three scent-hound breeds Bavarian mountain hound (BMH), Hanoverian hound (HH) and Tyrolean hound (TH) using all available pedigree information from scent-hound kennel clubs for these three breeds throughout Europe. The pedigree data of the BMH and the HH date back to 1912 and 1894, respectively. Pedigree data of the TH were available from the 1960s onwards. The reference populations included all BMH (n = 3231), HH (n = 1371) and TH (n = 1167) dogs registered between 1992 and 2004. Average generation intervals were 5.3 years for the BMH and 5.0 years for the HH and TH. Average inbreeding coefficients for the reference populations were 4.5%, 6.8% and 9.5% for the BMH, HH and TH. The effective numbers of founders, ancestors and founder genomes were lowest for the TH and highest for the BMH. The effective numbers of founder genomes were 10.9, 5.6 and 4.3 for the BMH, HH and TH. Effective population size was largest for the BMH with 72.7 effective breeding animals, followed by the HH with 50.9 and TH with 26.5. The most important ten ancestors had genetic contributions to the reference populations of 54.4%, 65.2% and 77.9% in the BMH, HH and TH. The results of our study indicate the need for careful breed management in these highly specialized hound breeds to maintain genetic diversity. European stud books should be established for these dog breeds in order to avoid inbreeding due to missing pedigree records.

[The investigation of the influence of cryopreservation and inbreeding on the variability of morphological characteristics of the evening-primrose biennial (Oenothera biennis L.)].

Science.gov (United States)

Chetviverikova, E P; Iashina, S G; Shabaeva, E V; Egorova, E F; Iashina, A V

2005-01-01

The effect of deep freezing of seeds at -196 degrees C (-320.8 degrees Fahrenheit) and inbreeding on the morphological characteristics of the evening-primrose biennal (Oenothera biennis L.), such as the size of plant parts and the amount of fruits, cauline nodes, and generative and vegetative shoots was investigated. The variation coefficients for these characteristics after treatment with low temperatures and inbreeding were calculated. It was shown that the characteristics of plant size show a low and a middle level of variability in the control group. The variation curves for these characteristics are similar to normal distribution curves. After stresses they slightly change or remain invariant. Large adventive shoots show a high level of variability. The distribution of the results in this case significantly differs from the normal. The branching of plants changes after both stress factors: the amount of all kinds of shoots decreases by half or even more.

Efficient Implementation of Nested-Loop Multimedia Algorithms

Directory of Open Access Journals (Sweden)

Kittitornkun Surin

2001-01-01

Full Text Available A novel dependence graph representation called the multiple-order dependence graph for nested-loop formulated multimedia signal processing algorithms is proposed. It allows a concise representation of an entire family of dependence graphs. This powerful representation facilitates the development of innovative implementation approach for nested-loop formulated multimedia algorithms such as motion estimation, matrix-matrix product, 2D linear transform, and others. In particular, algebraic linear mapping (assignment and scheduling methodology can be applied to implement such algorithms on an array of simple-processing elements. The feasibility of this new approach is demonstrated in three major target architectures: application-specific integrated circuit (ASIC, field programmable gate array (FPGA, and a programmable clustered VLIW processor.

Random walk loop soups and conformal loop ensembles

NARCIS (Netherlands)

van de Brug, T.; Camia, F.; Lis, M.

2016-01-01

The random walk loop soup is a Poissonian ensemble of lattice loops; it has been extensively studied because of its connections to the discrete Gaussian free field, but was originally introduced by Lawler and Trujillo Ferreras as a discrete version of the Brownian loop soup of Lawler and Werner, a

Constructing QCD one-loop amplitudes

International Nuclear Information System (INIS)

Forde, D

2008-01-01

other new methods have also proved fruitful for calculating rational terms [8]. Such developments have again refocused attention on the optimization of the derivation of the cut-constructable pieces of the amplitude. Deriving cut-constructible terms for any one-loop amplitude reduces to the computation of coefficients of a set of scalar bubble, scalar triangle and scalar box integral functions. Box coefficients may be found with very little work, directly from the quadruple cut of the relevant box function [9]. A unique box coefficient contributes to each distinct quadruple cut. Unfortunately triangle and bubble coefficients cannot be derived in quite so direct a manner. Multiple scalar integral coefficients appear inside a two-particle cut or triple cut. It is therefore necessary to disentangle the relevant bubble or triangle coefficients from any other coefficients sharing the same cut [1, 4, 10, 11]. The large number of NLO processes of interest for the LHC suggests that a completely automated computational procedure is highly desired. To this end we discuss, in this proceeding, a recently proposed method [12, 13] for the direct, efficient and systematic extraction of bubble and triangle coefficients which is well suited to automation

A Robust Two-Phase Pumped Loop With Multiple Evaporators and Multiple Radiators, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA's future spacecraft require advanced thermal management technologies to provide effective cooling for multiple instruments and reject heat through multiple...

Steady state flow analysis of two-phase natural circulation in multiple parallel channel loop

International Nuclear Information System (INIS)

Bhusare, V.H.; Bagul, R.K.; Joshi, J.B.; Nayak, A.K.; Kannan, Umasankari; Pilkhwal, D.S.; Vijayan, P.K.

2016-01-01

Highlights: • Liquid circulation velocity increases with increasing superficial gas velocity. • Total two-phase pressure drop decreases with increasing superficial gas velocity. • Channels with larger driving force have maximum circulation velocities. • Good agreement between experimental and model predictions. - Abstract: In this work, steady state flow analysis has been carried out experimentally in order to estimate the liquid circulation velocities and two-phase pressure drop in air–water multichannel circulating loop. Experiments were performed in 15 channel circulating loop. Single phase and two-phase pressure drops in the channels have been measured experimentally and have been compared with theoretical model of Joshi et al. (1990). Experimental measurements show good agreement with model.

Self-optimizing Uplink Outer Loop Power Control for WCDMA Network

Directory of Open Access Journals (Sweden)

A. G. Markoc

2015-06-01

Full Text Available The increasing demands for high data rates, drives the efforts for more efficient usage of the finite natural radio spectrum resources. Existing wideband code division multiple access (WCDMA uplink outer loop power control has difficulty to answer to the new load on air interface. The main reason is that the maximum allowed noise rise per single user is fixed value. In worst case uplink load can be so high that all services, including conversational service, could be blocked. In this paper investigation has been performed to present correlation of main system parameters, used by uplink outer loop power control, to uplink load. Simulation has been created and executed to present difference in current implementation of uplink outer loop power control against proposed changes. Proposed solution is self-optimizing uplink outer loop power control in a way that maximum allowed noise rise per single user would be dynamically changed based on current uplink load on cell.

Marker Assisted Selection can Reduce True as well as Pedigree Estimated Inbreeding

DEFF Research Database (Denmark)

Pedersen, L D; Sørensen, A C; Berg, P

2009-01-01

This study investigated whether selection using genotype information reduced the rate and level of true inbreeding, that is, identity by descent, at a selectively neutral locus as well as a locus under selection compared with traditional BLUP selection. In addition, the founder representation...... each of 40 herds. Selection was performed using BLUP, marker-assisted, or gene-assisted selection for a trait with low heritability (h2 = 0.04) only expressed in females, mimicking a health trait. The simulated genome consisted of 2 chromosomes. One biallelic quantitative trait loci (QTL......) with an initial frequency of the favorable allele of 0.1, and initially explaining 25% of the genetic variance as well as 4 markers were simulated in linkage disequilibrium, all positioned at chromosome 1. Chromosome 2 was selectively neutral, and consisted of a single neutral locus. The results showed...

CFD simulation of a four-loop PWR at asymmetric operation conditions

Energy Technology Data Exchange (ETDEWEB)

Cheng, Jian-Ping; Yan, Li-Ming; Li, Feng-Chen, E-mail: lifch@hit.edu.cn

2016-04-15

Highlights: • A CFD numerical simulation procedure was established for simulating RPV of VVER-1000. • The established CFD approach was validated by comparing with available data. • Thermal hydraulic characteristics under asymmetric operation condition were investigated. • Apparent influences of the shutdown loop on its neighboring loops were obtained. - Abstract: The pressurized water reactor (PWR) with multiple loops may have abnormal working conditions with coolant pumps out of running in some loops. In this paper, a computational fluid dynamics (CFD) numerical study of the four-loop VVER-1000 PWR pressure vessel model was presented. Numerical simulations of the thermohydrodynamic characteristics in the pressure vessel were carried out at different inlet conditions with four and three loops running, respectively. At normal stead-state condition (four-loop running), different parameters were obtained for the full fluid domain, including pressure losses across different parts, pressure, velocity and temperature distributions in the reactor pressure vessel (RPV) and mass flow distribution of the coolant at the inlet of reactor core. The obtained results for pressure losses matched with the experimental reference values of the VVER-1000 PWR at Tianwan nuclear power plant (NPP). For most fuel assemblies (FAs), the inlet flow rates presented a symmetrical distribution about the center under full-loop operation conditions, which accorded with the practical distribution. These results indicate that it is now possible to study the dynamic transition process between different asymmetric operation conditions in a multi-loop PWR using the established CFD method.

Explicit formuli for one, two, three and four loops string amplitudes in critical dimension

International Nuclear Information System (INIS)

Morozov, A.Yu.

1987-01-01

A report on explicit formulae for loop string diagrams in the primary-quantized theory of strings is presented. In the critical dimension d=26 tachyon p-loop scattering amplitude in the theory of boson strings is presented as finite-multiple integral with respect to Riemann surface M p moduli space. Integration on M p in continual integral is determined

Acceleration of Feynman loop integrals in high-energy physics on many core GPUs

International Nuclear Information System (INIS)

Yuasa, F; Ishikawa, T; Hamaguchi, N; Koike, T; Nakasato, N

2013-01-01

The current and future colliders in high-energy physics require theorists to carry out a large scale computation for a precise comparison between experimental results and theoretical ones. In a perturbative approach several methods to evaluate Feynman loop integrals which appear in the theoretical calculation of cross-sections are well established in the one-loop level, however, more studies are necessary for higher-order levels. Direct Computation Method (DCM) is developed to evaluate multi-loop integrals. DCM is based on a combination of multidimensional numerical integration and extrapolation on a sequence of integrals. It is a fully numerical method and is applicable to a wide class of integrals with various physics parameters. The computation time depends on physics parameters and the topology of loop diagrams and it becomes longer for the two-loop integrals. In this paper we present our approach to the acceleration of the two-loop integrals by DCM on multiple GPU boards

Validity and Reliability of Orthodontic Loops between Mechanical Testing and Computer Simulation: An Finite Element Method Study

Directory of Open Access Journals (Sweden)

Gaurav Sepolia

2014-01-01

Full Text Available The magnitude and direction of orthodontic force is one of the essential concerns of orthodontic tooth movements. Excessive force may cause root resorption and mobility of the tooth, whereas low force level may results in prolonged treatment. The addition of loops allows the clinician to more accurately achieve the desired results. Aims and objectives: The purpose of the study was to evaluate the validity and reliability of orthodontic loops between mechanical testing and computer simulation. Materials and methods: Different types of loops were taken and divided into four groups: The Teardrop loop, Opus loop, L loop and T loop. These were artificially activated for multiple lengths and studied using the FEM. Results: The Teardrop loop showed the highest force level, and there is no significant difference between mechanical testing and computer simulation.

Genetic Gain and Inbreeding from Genomic Selection in a Simulated Commercial Breeding Program for Perennial Ryegrass

Directory of Open Access Journals (Sweden)

Zibei Lin

2016-03-01

Full Text Available Genomic selection (GS provides an attractive option for accelerating genetic gain in perennial ryegrass ( improvement given the long cycle times of most current breeding programs. The present study used simulation to investigate the level of genetic gain and inbreeding obtained from GS breeding strategies compared with traditional breeding strategies for key traits (persistency, yield, and flowering time. Base population genomes were simulated through random mating for 60,000 generations at an effective population size of 10,000. The degree of linkage disequilibrium (LD in the resulting population was compared with that obtained from empirical studies. Initial parental varieties were simulated to match diversity of current commercial cultivars. Genomic selection was designed to fit into a company breeding program at two selection points in the breeding cycle (spaced plants and miniplot. Genomic estimated breeding values (GEBVs for productivity traits were trained with phenotypes and genotypes from plots. Accuracy of GEBVs was 0.24 for persistency and 0.36 for yield for single plants, while for plots it was lower (0.17 and 0.19, respectively. Higher accuracy of GEBVs was obtained for flowering time (up to 0.7, partially as a result of the larger reference population size that was available from the clonal row stage. The availability of GEBVs permit a 4-yr reduction in cycle time, which led to at least a doubling and trebling genetic gain for persistency and yield, respectively, than the traditional program. However, a higher rate of inbreeding per cycle among varieties was also observed for the GS strategy.

Genetic Gain and Inbreeding from Genomic Selection in a Simulated Commercial Breeding Program for Perennial Ryegrass.

Science.gov (United States)

Lin, Zibei; Cogan, Noel O I; Pembleton, Luke W; Spangenberg, German C; Forster, John W; Hayes, Ben J; Daetwyler, Hans D

2016-03-01

Genomic selection (GS) provides an attractive option for accelerating genetic gain in perennial ryegrass () improvement given the long cycle times of most current breeding programs. The present study used simulation to investigate the level of genetic gain and inbreeding obtained from GS breeding strategies compared with traditional breeding strategies for key traits (persistency, yield, and flowering time). Base population genomes were simulated through random mating for 60,000 generations at an effective population size of 10,000. The degree of linkage disequilibrium (LD) in the resulting population was compared with that obtained from empirical studies. Initial parental varieties were simulated to match diversity of current commercial cultivars. Genomic selection was designed to fit into a company breeding program at two selection points in the breeding cycle (spaced plants and miniplot). Genomic estimated breeding values (GEBVs) for productivity traits were trained with phenotypes and genotypes from plots. Accuracy of GEBVs was 0.24 for persistency and 0.36 for yield for single plants, while for plots it was lower (0.17 and 0.19, respectively). Higher accuracy of GEBVs was obtained for flowering time (up to 0.7), partially as a result of the larger reference population size that was available from the clonal row stage. The availability of GEBVs permit a 4-yr reduction in cycle time, which led to at least a doubling and trebling genetic gain for persistency and yield, respectively, than the traditional program. However, a higher rate of inbreeding per cycle among varieties was also observed for the GS strategy. Copyright © 2016 Crop Science Society of America.

Two-loop hard-thermal-loop thermodynamics with quarks

International Nuclear Information System (INIS)

Andersen, Jens O.; Petitgirard, Emmanuel; Strickland, Michael

2004-01-01

We calculate the quark contribution to the free energy of a hot quark-gluon plasma to two-loop order using hard-thermal-loop (HTL) perturbation theory. All ultraviolet divergences can be absorbed into renormalizations of the vacuum energy and the HTL quark and gluon mass parameters. The quark and gluon HTL mass parameters are determined self-consistently by a variational prescription. Combining the quark contribution with the two-loop HTL perturbation theory free energy for pure glue we obtain the total two-loop QCD free energy. Comparisons are made with lattice estimates of the free energy for N f =2 and with exact numerical results obtained in the large-N f limit

Multiple-source multiple-harmonic active vibration control of variable section cylindrical structures: A numerical study

Science.gov (United States)

Liu, Jinxin; Chen, Xuefeng; Gao, Jiawei; Zhang, Xingwu

2016-12-01

Air vehicles, space vehicles and underwater vehicles, the cabins of which can be viewed as variable section cylindrical structures, have multiple rotational vibration sources (e.g., engines, propellers, compressors and motors), making the spectrum of noise multiple-harmonic. The suppression of such noise has been a focus of interests in the field of active vibration control (AVC). In this paper, a multiple-source multiple-harmonic (MSMH) active vibration suppression algorithm with feed-forward structure is proposed based on reference amplitude rectification and conjugate gradient method (CGM). An AVC simulation scheme called finite element model in-loop simulation (FEMILS) is also proposed for rapid algorithm verification. Numerical studies of AVC are conducted on a variable section cylindrical structure based on the proposed MSMH algorithm and FEMILS scheme. It can be seen from the numerical studies that: (1) the proposed MSMH algorithm can individually suppress each component of the multiple-harmonic noise with an unified and improved convergence rate; (2) the FEMILS scheme is convenient and straightforward for multiple-source simulations with an acceptable loop time. Moreover, the simulations have similar procedure to real-life control and can be easily extended to physical model platform.

LoopIng: a template-based tool for predicting the structure of protein loops.

KAUST Repository

Messih, Mario Abdel; Lepore, Rosalba; Tramontano, Anna

2015-01-01

) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has

Closed-loop, open-source electrophysiology

Directory of Open Access Journals (Sweden)

John D Rolston

2010-09-01

Full Text Available Multiple extracellular microelectrodes (multi-electrode arrays, or MEAs effectively record rapidly varying neural signals, and can also be used for electrical stimulation. Multi-electrode recording can serve as artificial output (efferents from a neural system, while complex spatially and temporally targeted stimulation can serve as artificial input (afferents to the neuronal network. Multi-unit or local field potential recordings can not only be used to control real world artifacts, such as prostheses, computers or robots, but can also trigger or alter subsequent stimulation. Real-time feedback stimulation may serve to modulate or normalize aberrant neural activity, to induce plasticity, or to serve as artificial sensory input. Despite promising closed-loop applications, commercial electrophysiology systems do not yet take advantage of the bidirectional capabilities of multi-electrodes, especially for use in freely moving animals. We addressed this lack of tools for closing the loop with NeuroRighter, an open-source system including recording hardware, stimulation hardware, and control software with a graphical user interface. The integrated system is capable of multi-electrode recording and simultaneous patterned microstimulation triggered by recordings with minimal stimulation artifact. The potential applications of closed-loop systems as research tools and clinical treatments are broad; we provide one example where epileptic activity recorded by a multi-electrode probe is used to trigger targeted stimulation, via that probe, to freely moving rodents.

Multiple Description Coding for Closed Loop Systems over Erasure Channels

DEFF Research Database (Denmark)

Østergaard, Jan; Quevedo, Daniel

2013-01-01

In this paper, we consider robust source coding in closed-loop systems. In particular, we consider a (possibly) unstable LTI system, which is to be stabilized via a network. The network has random delays and erasures on the data-rate limited (digital) forward channel between the encoder (controller......) and the decoder (plant). The feedback channel from the decoder to the encoder is assumed noiseless. Since the forward channel is digital, we need to employ quantization.We combine two techniques to enhance the reliability of the system. First, in order to guarantee that the system remains stable during packet...... by showing that the system can be cast as a Markov jump linear system....

Power in the loop real time simulation platform for renewable energy generation

Science.gov (United States)

Li, Yang; Shi, Wenhui; Zhang, Xing; He, Guoqing

2018-02-01

Nowadays, a large scale of renewable energy sources has been connecting to power system and the real time simulation platform is widely used to carry out research on integration control algorithm, power system stability etc. Compared to traditional pure digital simulation and hardware in the loop simulation, power in the loop simulation has higher accuracy and degree of reliability. In this paper, a power in the loop analog digital hybrid simulation platform has been built and it can be used not only for the single generation unit connecting to grid, but also for multiple new energy generation units connecting to grid. A wind generator inertia control experiment was carried out on the platform. The structure of the inertia control platform was researched and the results verify that the platform is up to need for renewable power in the loop real time simulation.

Study on LOOP and SBO Frequency for Multi-Unit PSA

Energy Technology Data Exchange (ETDEWEB)

Jin, Kyung Ho; Heo, Gyun Young [Kyunghee University, Yongin (Korea, Republic of)

2016-05-15

In conventional single unit PSA, it was assumed that all accidents or events are independent and the risk of only one unit has been evaluated. In other words, the possibility that simultaneous events occur on multiple units was excluded because it was assumed that the probability of concurrent events were extremely low. After Fukushima accidents, however, it was found that external hazards such as tsunami may impact on multiple units; that means, for the sake of proper mitigation the risk of accidents in shared SSCs should be reevaluated. New risk metrics to improve conventional CDF (Core Damage frequency) based on reactor-year is needed to perform MUPSA (Multi-Unit Probabilistic Safety Assessment). IAEA suggested SCDF (Site CDF) as a risk metrics for MUPSA. The frequency based on reactor-year was converted to the frequency based on site-year. In addition, shared SSCs were modeled in single unit PSA as if those units have independent shared SSCs. Therefore, the risk of shared SSCs should be reevaluated. In this paper, the frequency of LOOP (Loss of Offsite Power), which is typically a multi-unit event, was evaluated and the frequency of SBO (Station Blackout) depending on LOOP frequency and emergency power systems such as EDG (Emergency Diesel Generator) and AAC (Alternate AC), that can mitigate SBO events, was modeled. This paper describes how to calculate LOOP and SBO frequency from the simple example for two-unit site with shared AAC. The events impacting on multiple units, which were excluded in conventional PSA, should be considered for MUPSA.

Neocortical electrical stimulation for epilepsy : Closed-loop versus open-loop

NARCIS (Netherlands)

Vassileva, Albena; van Blooijs, Dorien; Leijten, Frans; Huiskamp, Geertjan

2018-01-01

The aim of this review is to evaluate whether open-loop or closed-loop neocortical electrical stimulation should be the preferred approach to manage seizures in intractable epilepsy. Twenty cases of open-loop neocortical stimulation with an implanted device have been reported, in 5 case studies.

DETECTING NANOFLARE HEATING EVENTS IN SUBARCSECOND INTER-MOSS LOOPS USING Hi-C

International Nuclear Information System (INIS)

Winebarger, Amy R.; Moore, Ronald; Cirtain, Jonathan; Walsh, Robert W.; De Pontieu, Bart; Title, Alan; Hansteen, Viggo; Golub, Leon; Korreck, Kelly; Weber, Mark; Kobayashi, Ken; DeForest, Craig; Kuzin, Sergey

2013-01-01

The High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket on 2012 July 11 and captured roughly 345 s of high-spatial and temporal resolution images of the solar corona in a narrowband 193 Å channel. In this paper, we analyze a set of rapidly evolving loops that appear in an inter-moss region. We select six loops that both appear in and fade out of the Hi-C images during the short flight. From the Hi-C data, we determine the size and lifetimes of the loops and characterize whether these loops appear simultaneously along their length or first appear at one footpoint before appearing at the other. Using co-aligned, co-temporal data from multiple channels of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, we determine the temperature and density of the loops. We find the loops consist of cool (∼10 5 K), dense (∼10 10 cm –3 ) plasma. Their required thermal energy and their observed evolution suggest they result from impulsive heating similar in magnitude to nanoflares. Comparisons with advanced numerical simulations indicate that such dense, cold and short-lived loops are a natural consequence of impulsive magnetic energy release by reconnection of braided magnetic field at low heights in the solar atmosphere.

A gauge/gravity relation in the one-loop effective action

International Nuclear Information System (INIS)

Basar, Goekce; Dunne, Gerald V

2010-01-01

We identify an unusual new gauge/gravity relation: the one-loop effective action for a massive spinor in 2n-dimensional AdS space is expressed in terms of precisely the same function (a certain multiple gamma function) as the one-loop effective action for a massive charged scalar in 4n dimensions in a maximally symmetric background electromagnetic field (one for which the eigenvalues of F μν are maximally degenerate, corresponding in four dimensions to a self-dual field, equivalently to a field of definite helicity), subject to the identification F 2 ↔Λ, where Λ is the gravitational curvature. Since these effective actions generate the low energy limit of all one-loop multi-leg graviton or gauge amplitudes, this implies a nontrivial gauge/gravity relation at the non-perturbative level and at the amplitude level. (fast track communication)

Finding Positive Feedback Loops in Environmental Models: A Mathematical Investigation

Science.gov (United States)

Sheikholeslami, R.; Razavi, S.

2016-12-01

Dynamics of most earth and environmental systems are generally governed by interactions between several hydrological (e.g., soil moisture and precipitation), geological (e.g., and erosion), geochemical (e.g., nutrient loading), and atmospheric (e.g., temperature) processes which operate on a range of spatio-temporal scales. These interactions create numerous feedback mechanisms with complex behaviours, and their understanding and representation can vary depending on the scale in space and/or time at which the system is analyzed. One of the most crucial characteristics of such complex systems is the existence of positive feedback loops. The presence of positive feedbacks may increase complexity, accelerate change, or trigger multiple stable states in the underlying dynamical system. Furthermore, because of the inherent non-linearity, it is often very difficult to obtain a general idea of their complex dynamics. Feedback loops in environmental systems have been well recognized and qualitatively discussed. With a quantitative/mathematical view, in this presentation, we address the question of how the positive feedback loops can be identified/implemented in environmental models. We investigate the nature of different feedback mechanisms and dynamics of simple example case studies that underlie fundamental processes such as vegetation, precipitation and soil moisture. To do this, we apply the concept of "interaction graph" from mathematics which is built from the Jacobian matrix of the dynamical system. The Jacobian matrix contains information on how variations of one state variable depends on variations of other variables, and thus can be used to understand the dynamical possibilities of feedback mechanisms in the underlying system. Moreover, this study highlights that there are some situations where the existence of positive feedback loops can cause multiple stable states, and thereby regime shifts in environmental systems. Systems with multiple stable states are

Evidence of high inbreeding in a population of the endangered giant anteater, Myrmecophaga tridactyla (Myrmecophagidae), from Emas National Park, Brazil

OpenAIRE

Collevatti, Rosane G.; Leite, Kelly C.E.; Miranda, Guilherme H.B. de; Rodrigues, Flavio H.G.

2007-01-01

We report the genetic structure, relatedness and mating structure of a population of the endangered giant anteater Myrmecophaga tridactyla Linnaeus, 1758 in the Emas National Park, Brazil, based on variability at five microsatellite loci. Additionally, we addressed the hypothesis that the M. tridactyla population studied has low levels of polymorphism and high levels of inbreeding and relatedness and that animals with overlapping home range are highly related. All five microsatellite loci dis...

MS vs. pole masses of gauge bosons II: Two-loop electroweak fermion correct

International Nuclear Information System (INIS)

Jegerlehner, F.; Kalmykov, M.Yu.; Veretin, O.

2002-12-01

We have calculated the fermion contributions to the shift of the position of the poles of the massive gauge boson propagators at two-loop order in the Standard Model. Together with the bosonic contributions calculated previously the full two-loop corrections are available. This allows us to investigate the full correction in the relationship between anti M anti S and pole masses of the vector bosons Z and W. Two-loop renormalization and the corresponding renormalization group equations are discussed. Analytical results for the master-integrals appearing in the massless fermion contributions are given. A new approach of summing multiple binomial sums has been developed. (orig.)

Sequence-structure relationships in RNA loops: establishing the basis for loop homology modeling.

Science.gov (United States)

Schudoma, Christian; May, Patrick; Nikiforova, Viktoria; Walther, Dirk

2010-01-01

The specific function of RNA molecules frequently resides in their seemingly unstructured loop regions. We performed a systematic analysis of RNA loops extracted from experimentally determined three-dimensional structures of RNA molecules. A comprehensive loop-structure data set was created and organized into distinct clusters based on structural and sequence similarity. We detected clear evidence of the hallmark of homology present in the sequence-structure relationships in loops. Loops differing by structures. Thus, our results support the application of homology modeling for RNA loop model building. We established a threshold that may guide the sequence divergence-based selection of template structures for RNA loop homology modeling. Of all possible sequences that are, under the assumption of isosteric relationships, theoretically compatible with actual sequences observed in RNA structures, only a small fraction is contained in the Rfam database of RNA sequences and classes implying that the actual RNA loop space may consist of a limited number of unique loop structures and conserved sequences. The loop-structure data sets are made available via an online database, RLooM. RLooM also offers functionalities for the modeling of RNA loop structures in support of RNA engineering and design efforts.

Plasma dynamics above solar flare soft x-ray loop tops

Energy Technology Data Exchange (ETDEWEB)

Doschek, G. A.; Warren, H. P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); McKenzie, D. E. [Montana State University, Bozeman, MT 59717 (United States)

2014-06-10

We measure non-thermal motions in flare loop tops and above the loop tops using profiles of highly ionized spectral lines of Fe XXIV and Fe XXIII formed at multimillion-degree temperatures. Non-thermal motions that may be due to turbulence or multiple flow regions along the line of sight are extracted from the line profiles. The non-thermal motions are measured for four flares seen at or close to the solar limb. The profile data are obtained using the Extreme-ultraviolet Imaging Spectrometer on the Hinode spacecraft. The multimillion-degree non-thermal motions are between 20 and 60 km s{sup –1} and appear to increase with height above the loop tops. Motions determined from coronal lines (i.e., lines formed at about 1.5 MK) tend to be smaller. The multimillion-degree temperatures in the loop tops and above range from about 11 MK to 15 MK and also tend to increase with height above the bright X-ray-emitting loop tops. The non-thermal motions measured along the line of sight, as well as their apparent increase with height, are supported by Solar Dynamics Observatory Atmospheric Imaging Assembly measurements of turbulent velocities in the plane of the sky.

Impact of selective logging on inbreeding and gene dispersal in an Amazonian tree population of Carapa guianensis Aubl.

Science.gov (United States)

Cloutier, D; Kanashiro, M; Ciampi, A Y; Schoen, D J

2007-02-01

Selective logging may impact patterns of genetic diversity within populations of harvested forest tree species by increasing distances separating conspecific trees, and modifying physical and biotic features of the forest habitat. We measured levels of gene diversity, inbreeding, pollen dispersal and spatial genetic structure (SGS) of an Amazonian insect-pollinated Carapa guianensis population before and after commercial selective logging. Similar levels of gene diversity and allelic richness were found before and after logging in both the adult and the seed generations. Pre- and post-harvest outcrossing rates were high, and not significantly different from one another. We found no significant levels of biparental inbreeding either before or after logging. Low levels of pollen pool differentiation were found, and the pre- vs. post-harvest difference was not significant. Pollen dispersal distance estimates averaged between 75 m and 265 m before logging, and between 76 m and 268 m after logging, depending on the value of tree density and the dispersal model used. There were weak and similar levels of differentiation of allele frequencies in the adults and in the pollen pool, before and after logging occurred, as well as weak and similar pre- and post-harvest levels of SGS among adult trees. The large neighbourhood sizes estimated suggest high historical levels of gene flow. Overall our results indicate that there is no clear short-term genetic impact of selective logging on this population of C. guianensis.

Ukuran Populasi Efektif, Ukuran Populasi Aktual dan Laju Inbreeding Per Generasi Itik Lokal di Kecamatan Tilatang Kamang Kabupaten Agam

OpenAIRE

Rusfidra, Rusfidra; Zein, R; Hasibuan, A. M. A

2012-01-01

This study aims to obtain the effective population size, actual population size and rate of inbreeding of Kamang local duck. In this study used a sample local duck raised from 30 farmers. This research conducted was survey method with purposive random sampling. The variables were calculated in the study, namely the number of adult male ducks (Nm), number of adult female ducks (Nf), number of young male and young female ducks, number of male and female ducklings, actual population size (Na), e...

Hexagon functions and the three-loop remainder function

Energy Technology Data Exchange (ETDEWEB)

Dixon, Lance J.; Drummond, James M.; von Hippel, Matt; Pennington, Jeffrey

2013-12-01

We present the three-loop remainder function, which describes the scattering of six gluons in the maximally-helicity-violating configuration in planar NN = 4 super-Yang-Mills theory, as a function of the three dual conformal cross ratios. The result can be expressed in terms of multiple Goncharov polylogarithms. We also employ a more restricted class of hexagon functions which have the correct branch cuts and certain other restrictions on their symbols. We classify all the hexagon functions through transcendental weight five, using the coproduct for their Hopf algebra iteratively, which amounts to a set of first-order differential equations. The three-loop remainder function is a particular weight-six hexagon function, whose symbol was determined previously. The differential equations can be integrated numerically for generic values of the cross ratios, or analytically in certain kinematic limits, including the near-collinear and multi-Regge limits. These limits allow us to impose constraints from the operator product expansion and multi-Regge factorization directly at the function level, and thereby to fix uniquely a set of Riemann ζ valued constants that could not be fixed at the level of the symbol. The near-collinear limits agree precisely with recent predictions by Basso, Sever and Vieira based on integrability. The multi-Regge limits agree with the factorization formula of Fadin and Lipatov, and determine three constants entering the impact factor at this order. We plot the three-loop remainder function for various slices of the Euclidean region of positive cross ratios, and compare it to the two-loop one. For large ranges of the cross ratios, the ratio of the three-loop to the two-loop remainder function is relatively constant, and close to -7.

Beating of Aharonov-Bohm oscillations in a closed-loop interferometer

International Nuclear Information System (INIS)

Jo, Sanghyun; Chang, Dong-In; Lee, Hu-Jong; Khym, Gyong Luck; Kang, Kicheon; Chung, Yunchul; Mahalu, Diana; Umansky, Vladimir

2007-01-01

One of the points at issue with closed-loop-type interferometers is beating in the Aharonov-Bohm (AB) oscillations. Recent observations suggest the possibility that the beating results from the Berry-phase pickup by the conducting electrons in materials with the strong spin-orbit interaction (SOI). In this study, we also observed beats in the AB oscillations in a gate-defined closed-loop interferometer fabricated on a GaAs/Al 0.3 Ga 0.7 As two-dimensional electron-gas heterostructure. Since this heterostructure has very small SOI, the picture of the Berry-phase pickup is ruled out. The observation of beats in this study, with the controllability of forming a single transverse subband mode in both arms of our gate-defined interferometer, also rules out the often-claimed multiple transverse subband effect. It is observed that nodes of the beats with an h/2e period exhibit a parabolic distribution for varying the side gate. These results are shown to be well interpreted, without resorting to the SOI effect, by the existence of two-dimensional multiple longitudinal modes in a single transverse subband. The Fourier spectrum of measured conductance, despite showing multiple h/e peaks with the magnetic-field dependence that are very similar to that from strong-SOI materials, can also be interpreted as the two-dimensional multiple-longitudinal-modes effect

LOOP CALCULUS AND BELIEF PROPAGATION FOR Q-ARY ALPHABET: LOOP TOWER

Energy Technology Data Exchange (ETDEWEB)

CHERTKOV, MICHAEL [Los Alamos National Laboratory; CHERNYAK, VLADIMIR [Los Alamos National Laboratory

2007-01-10

Loop calculus introduced in [1], [2] constitutes a new theoretical tool that explicitly expresses symbol Maximum-A-Posteriori (MAP) solution of a general statistical inference problem via a solution of the Belief Propagation (BP) equations. This finding brought a new significance to the BP concept, which in the past was thought of as just a loop-free approximation. In this paper they continue a discussion of the Loop Calculus, partitioning the results into three Sections. In Section 1 they introduce a new formulation of the Loop Calculus in terms of a set of transformations (gauges) that keeping the partition function of the problem invariant. The full expression contains two terms referred to as the 'ground state' and 'excited states' contributions. The BP equations are interpreted as a special (BP) gauge fixing condition that emerges as a special orthogonality constraint between the ground state and excited states, which also selects loop contributions as the only surviving ones among the excited states. In Section 2 they demonstrate how the invariant interpretation of the Loop Calculus, introduced in Section 1, allows a natural extension to the case of a general q-ary alphabet, this is achieved via a loop tower sequential construction. The ground level in the tower is exactly equivalent to assigning one color (out of q available) to the 'ground state' and considering all 'excited' states colored in the remaining (q-1) colors, according to the loop calculus rule. Sequentially, the second level in the tower corresponds to selecting a loop from the previous step, colored in (q-1) colors, and repeating the same ground vs excited states splitting procedure into one and (q-2) colors respectively. The construction proceeds till the full (q-1)-levels deep loop tower (and the corresponding contributions to the partition function) are established. In Section 3 they discuss an ultimate relation between the loop calculus and the Bethe

DETECTING NANOFLARE HEATING EVENTS IN SUBARCSECOND INTER-MOSS LOOPS USING Hi-C

Energy Technology Data Exchange (ETDEWEB)

Winebarger, Amy R.; Moore, Ronald; Cirtain, Jonathan [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Walsh, Robert W. [University of Central Lancashire, Preston, Lancashire PR1 2HE (United Kingdom); De Pontieu, Bart; Title, Alan [Lockheed Martin Solar and Astrophysics Lab, 3251 Hanover St., Org. A0215, Bldg. 252, Palo Alto, CA 94304 (United States); Hansteen, Viggo [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, N-0315 Oslo (Norway); Golub, Leon; Korreck, Kelly; Weber, Mark [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Kobayashi, Ken [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Dr, Huntsville, AL 35805 (United States); DeForest, Craig [Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302 (United States); Kuzin, Sergey, E-mail: amy.r.winebarger@nasa.gov [P.N. Lebedev Physical institute of the Russian Academy of Sciences, Leninskii prospekt 53 119991, Moscow (Russian Federation)

2013-07-01

The High-resolution Coronal Imager (Hi-C) flew aboard a NASA sounding rocket on 2012 July 11 and captured roughly 345 s of high-spatial and temporal resolution images of the solar corona in a narrowband 193 A channel. In this paper, we analyze a set of rapidly evolving loops that appear in an inter-moss region. We select six loops that both appear in and fade out of the Hi-C images during the short flight. From the Hi-C data, we determine the size and lifetimes of the loops and characterize whether these loops appear simultaneously along their length or first appear at one footpoint before appearing at the other. Using co-aligned, co-temporal data from multiple channels of the Atmospheric Imaging Assembly on the Solar Dynamics Observatory, we determine the temperature and density of the loops. We find the loops consist of cool ({approx}10{sup 5} K), dense ({approx}10{sup 10} cm{sup -3}) plasma. Their required thermal energy and their observed evolution suggest they result from impulsive heating similar in magnitude to nanoflares. Comparisons with advanced numerical simulations indicate that such dense, cold and short-lived loops are a natural consequence of impulsive magnetic energy release by reconnection of braided magnetic field at low heights in the solar atmosphere.

Introduction to Loop Heat Pipes

Science.gov (United States)

Ku, Jentung

2015-01-01

This is the presentation file for the short course Introduction to Loop Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. This course will discuss operating principles and performance characteristics of a loop heat pipe. Topics include: 1) pressure profiles in the loop; 2) loop operating temperature; 3) operating temperature control; 4) loop startup; 4) loop shutdown; 5) loop transient behaviors; 6) sizing of loop components and determination of fluid inventory; 7) analytical modeling; 8) examples of flight applications; and 9) recent LHP developments.

Reactor loops at Chalk River

International Nuclear Information System (INIS)

Sochaski, R.O.

1962-07-01

This report describes broadly the nine in-reactor loops, and their components, located in and around the NRX and NRU reactors at Chalk River. First an introduction and general description is given of the loops and their function, supplemented with a table outlining some loop specifications and nine simplified flow sheets, one for each individual loop. The report then proceeds to classify each loop into two categories, the 'main loop circuit' and the 'auxiliary circuit', and descriptions are given of each circuit's components in turn. These components, in part, are comprised of the main loop pumps, the test section, loop heaters, loop coolers, delayed-neutron monitors, surge tank, Dowtherm coolers, loop piping. Here again photographs, drawings and tables are included to provide a clearer understanding of the descriptive literature and to include, in tables, some specifications of the more important components in each loop. (author)

Distribution of individual inbreeding coefficients, relatedness and influence of stocking on native anadromous brown trout ( Salmo trutta ) population structure

DEFF Research Database (Denmark)

Ruzzante, D.E.; Hansen, Michael Møller; Meldrup, Dorte

2001-01-01

inbreeding coefficients do not differ among locations within rivers. Relatedness varies between sites within rivers indicating varied local dynamics at a very small geographical scale. Relatedness is sometimes lower than expected among an equal number of simulated individuals with randomized genotypes......, the proportion of locally assigned trout correlates with the populations' stocking histories, with rivers presently subjected to stocking (hatchery trout) showing low mean similar to0.73), and rivers where stocking was discontinued showing high (mean similar to0.84) proportions of local fish, probably reflecting...

Interlinked Dual-Time Feedback Loops can Enhance Robustness to Stochasticity and Persistence of Memory

OpenAIRE

Smolen, Paul; Baxter, Douglas A.; Byrne, John H.

2012-01-01

Multiple interlinked positive feedback loops shape the stimulus responses of various biochemical systems, such as the cell cycle or intracellular Ca2+ release. Recent studies with simplified models have identified two advantages of coupling fast and slow feedback loops. This dual-time structure enables a fast response while enhancing resistances of responses and bistability to stimulus noise. We now find that: 1) the dual-time structure similarly confers resistance to internal noise due to mo...

Tracking performance of unbalanced QPSK demodulators. I - Biphase Costas loop with passive arm filters

Science.gov (United States)

Simon, M. K.; Alem, W. K.

1978-01-01

Unbalanced quadriphase-shift-keying (QPSK) is an attractive means for transmitting two digital data streams which in general have different average powers, data rates, and data formats. Previous analyses of the tracking performance of Costas loop demodulators of unbalanced QPSK have accounted only for the filtering effect produced by the loop's two arm filters on the equivalent additive noise perturbing the loop. When the bandwidth of these filters is selected on the basis of the order of the data rate, as is typical of optimum Costas loop design, the filtering degradations of the data modulations themselves and the cross-modulation noise produced by their multiplication in the loop often cannot be neglected. The purpose of this paper is to incorporate these additional filtering effects into the analysis. Many of the results obtained herein are in the form of closed-form expressions which can easily be evaluated numerically for design and performance prediction purposes.

Thermal Interface Evaluation of Heat Transfer from a Pumped Loop to Titanium-Water Thermosyphons

Science.gov (United States)

Jaworske, Donald A.; Sanzi, James L.; Gibson, Marc A.; Sechkar, Edward A.

2009-01-01

Titanium-water thermosyphons are being considered for use in the heat rejection system for lunar outpost fission surface power. Key to their use is heat transfer between a closed loop heat source and the heat pipe evaporators. This work describes laboratory testing of several interfaces that were evaluated for their thermal performance characteristics, in the temperature range of 350 to 400 K, utilizing a water closed loop heat source and multiple thermosyphon evaporator geometries. A gas gap calorimeter was used to measure heat flow at steady state. Thermocouples in the closed loop heat source and on the evaporator were used to measure thermal conductance. The interfaces were in two generic categories, those immersed in the water closed loop heat source and those clamped to the water closed loop heat source with differing thermal conductive agents. In general, immersed evaporators showed better overall performance than their clamped counterparts. Selected clamped evaporator geometries offered promise.

Distribution of sizes of erased loops for loop-erased random walks

OpenAIRE

Dhar, Deepak; Dhar, Abhishek

1997-01-01

We study the distribution of sizes of erased loops for loop-erased random walks on regular and fractal lattices. We show that for arbitrary graphs the probability $P(l)$ of generating a loop of perimeter $l$ is expressible in terms of the probability $P_{st}(l)$ of forming a loop of perimeter $l$ when a bond is added to a random spanning tree on the same graph by the simple relation $P(l)=P_{st}(l)/l$. On $d$-dimensional hypercubical lattices, $P(l)$ varies as $l^{-\\sigma}$ for large $l$, whe...

PHOTOSPHERIC PROPERTIES OF WARM EUV LOOPS AND HOT X-RAY LOOPS

Energy Technology Data Exchange (ETDEWEB)

Kano, R. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Ueda, K. [Department of Astronomy, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Tsuneta, S., E-mail: ryouhei.kano@nao.ac.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan)

2014-02-20

We investigate the photospheric properties (vector magnetic fields and horizontal velocity) of a well-developed active region, NOAA AR 10978, using the Hinode Solar Optical Telescope specifically to determine what gives rise to the temperature difference between ''warm loops'' (1-2 MK), which are coronal loops observed in EUV wavelengths, and ''hot loops'' (>3 MK), coronal loops observed in X-rays. We found that outside sunspots, the magnetic filling factor in the solar network varies with location and is anti-correlated with the horizontal random velocity. If we accept that the observed magnetic features consist of unresolved magnetic flux tubes, this anti-correlation can be explained by the ensemble average of flux-tube motion driven by small-scale random flows. The observed data are consistent with a flux tube width of ∼77 km and horizontal flow at ∼2.6 km s{sup –1} with a spatial scale of ∼120 km. We also found that outside sunspots, there is no significant difference between warm and hot loops either in the magnetic properties (except for the inclination) or in the horizontal random velocity at their footpoints, which are identified with the Hinode X-Ray Telescope and the Transition Region and Coronal Explorer. The energy flux injected into the coronal loops by the observed photospheric motion of the magnetic fields is estimated to be 2 × 10{sup 6} erg s{sup –1} cm{sup –2}, which is the same for both warm and hot loops. This suggests that coronal properties (e.g., loop length) play a more important role in giving rise to temperature differences of active-region coronal loops than photospheric parameters.

ANALYSIS AND MODELING OF TWO FLARE LOOPS OBSERVED BY AIA AND EIS

Energy Technology Data Exchange (ETDEWEB)

Li, Y.; Ding, M. D. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Qiu, J. [Department of Physics, Montana State University, Bozeman, MT 59717 (United States)

2012-10-10

We analyze and model an M1.0 flare observed by SDO/AIA and Hinode/EIS to investigate how flare loops are heated and evolve subsequently. The flare is composed of two distinctive loop systems observed in extreme ultraviolet (EUV) images. The UV 1600 A emission at the feet of these loops exhibits a rapid rise, followed by enhanced emission in different EUV channels observed by the Atmospheric Imaging Assembly (AIA) and the EUV Imaging Spectrometer (EIS). Such behavior is indicative of impulsive energy deposit and the subsequent response in overlying coronal loops that evolve through different temperatures. Using the method we recently developed, we infer empirical heating functions from the rapid rise of the UV light curves for the two loop systems, respectively, treating them as two big loops with cross-sectional area of 5'' by 5'', and compute the plasma evolution in the loops using the EBTEL model. We compute the synthetic EUV light curves, which, with the limitation of the model, reasonably agree with observed light curves obtained in multiple AIA channels and EIS lines: they show the same evolution trend and their magnitudes are comparable by within a factor of two. Furthermore, we also compare the computed mean enthalpy flow velocity with the Doppler shift measurements by EIS during the decay phase of the two loops. Our results suggest that the two different loops with different heating functions as inferred from their footpoint UV emission, combined with their different lengths as measured from imaging observations, give rise to different coronal plasma evolution patterns captured both in the model and in observations.

Deploying correct fault loop in distance protection of multiple-circuit shared tower transmission lines with different voltages

DEFF Research Database (Denmark)

Bak, Claus Leth; Silva, Filipe Miguel Faria da

2018-01-01

Combined faults occurring between different voltage levels in overhead lines present a challenge for distance protection. Previous work has shown that such faults most often appears as single phase to ground (SPTG) faults in a normal type of overhead line. However, it is not obvious that distance...... relays will identify and select the correct fault loop according to being similar to SPTG, as all six fault loops get excited when combined faults occur. This paper presents a study where two distance relays of different manufactures are tested using transient replay and secondary test equipment...

Variable Step Closed Loop Power Control with Space Diversity for Low Elevation Angle High Altitude Platforms Communication Channel [Langkah Variabel Kontrol Daya Loop Tertutup dengan Keragaman Ruang untuk Sudut Elevasi Rendah pada Kanal Komunikasi HAPs

Directory of Open Access Journals (Sweden)

Iskandar Iskandar

2016-07-01

Full Text Available This paper proposes variable step closed loop power control algorithm combined with space diversity to improve the performance of High Altitude Platforms (HAPs communication at low elevation angle using Code Division Multiple Access (CDMA. In this contribution, we first develop HAPs channel model which is derived from experimental measurement. From our experiment, we found HAPs channel characteristic can be modeled as a Ricean distribution because the presence of line of sight path. Different elevation angle resulting different K factor value.  This value is then used in Signal to Interference Ratio (SIR based closed loop power control evaluation. The variable step algorithm is simulated under various elevation angles with different speed of mobile user. The performance is presented in terms of user elevation angle, user speed, step size and space diversity order. We found that the performance of variable step closed-loop power control less effective at low elevation angle. However our simulation shows that space diversity is able to improve the performance of closed loop power control for HAPs channel at low elevation angle.*****Kajian ini mengusulkan suatu algoritma kontrol daya langkah variabel loop tertutup dikombinasikan dengan keragaman ruang untuk meningkatkan kinerja komunikasi High Altitude Platforms(HAPs pada sudut elevasi rendah menggunakan Code Division Multiple Access (CDMA. Kami berkontribusi untuk mengembangkan model kanal HAPs yang berasal dari pengukuran eksperimental sebelumnya. Dari percobaan tersebut, kami menemukan karakteristik kanal HAPs yang dapat dimodelkan sebagai distribusi Ricean karena kehadiran jalur tanpa penghalang. Eksperimen menunjukkan bahwa perbedaan sudut elevasi menghasilkan perbedaan nilai factor K. Nilai ini kemudian digunakan dalam Signal to Interference Ratio (SIR berbasiskan evaluasi kontrol daya loop tertutup. Algoritma langkah variabel disimulasikan dibawah sudut elevasi yang berbeda dengan kecepatan

Determination of the force systems produced by different configurations of tear drop orthodontic loops

Directory of Open Access Journals (Sweden)

Guilherme Thiesen

2013-04-01

Full Text Available OBJECTIVE: To determine the mechanical characteristics of teardrop loop with and without helix fabricated using different metal alloy compositions (stainless steel and beta-titanium, submitted to different intensities of bends preactivation (0º and 40º, and with different cross-sectional dimension of the wire used to build these loops (0.017 x 0.025-in and 0.019 x 0.025-in. METHODS: Eighty loops used to close spaces were submitted to mechanical tests. The magnitudes of horizontal force, the moment/force ratio, and the load/deflection ratio produced by the specimens were quantified. Loops were submitted to a total activation of 5.0 mm and the values were registered for each 1.0 mm of activation. For statistic data analysis, a analysis of variance was performed and a Tukey's Multiple Comparison test was used as supplement, considering a 5% level of significance. RESULTS: In general, teardrop loops with helix produced lower magnitudes of horizontal force and load/deflection ratio, and higher moment/force ratio than teardrop loops without helix. Among all analyzed variables, metal alloy composition presented greater influence in the horizontal force and in the load/deflection ratio. The moment/force ratio showed to be more influenced by the preactivation of loops for space closure.

Efficient Closed-Loop Schemes for MIMO-OFDM-Based WLANs

Directory of Open Access Journals (Sweden)

Jiang Yi

2006-01-01

Full Text Available The single-input single-output (SISO orthogonal frequency-division multiplexing (OFDM systems for wireless local area networks (WLAN defined by the IEEE 802.11a standard can support data rates up to 54 Mbps. In this paper, we consider deploying two transmit and two receive antennas to increase the data rate up to 108 Mbps. Applying our recent multiple-input multiple-output (MIMO transceiver designs, that is, the geometric mean decomposition (GMD and the uniform channel decomposition (UCD schemes, we propose simple and efficient closed-loop MIMO-OFDM designs for much improved performance, compared to the standard singular value decomposition (SVD based schemes as well as the open-loop V-BLAST (vertical Bell Labs layered space-time based counterparts. In the explicit feedback mode, precoder feedback is needed for the proposed schemes. We show that the overhead of feedback can be made very moderate by using a vector quantization method. In the time-division duplex (TDD mode where the channel reciprocity is exploited, our schemes turn out to be robust against the mismatch between the uplink and downlink channels. The advantages of our schemes are demonstrated via extensive numerical examples.

arXiv Diagrammatic Hopf algebra of cut Feynman integrals: the one-loop case

CERN Document Server

Abreu, Samuel; Duhr, Claude; Gardi, Einan

2017-12-15

We construct a diagrammatic coaction acting on one-loop Feynman graphs and their cuts. The graphs are naturally identified with the corresponding (cut) Feynman integrals in dimensional regularization, whose coefficients of the Laurent expansion in the dimensional regulator are multiple polylogarithms (MPLs). Our main result is the conjecture that this diagrammatic coaction reproduces the combinatorics of the coaction on MPLs order by order in the Laurent expansion. We show that our conjecture holds in a broad range of nontrivial one-loop integrals. We then explore its consequences for the study of discontinuities of Feynman integrals, and the differential equations that they satisfy. In particular, using the diagrammatic coaction along with information from cuts, we explicitly derive differential equations for any one-loop Feynman integral. We also explain how to construct the symbol of any one-loop Feynman integral recursively. Finally, we show that our diagrammatic coaction follows, in the special case of o...

Analytic results for planar three-loop integrals for massive form factors

Energy Technology Data Exchange (ETDEWEB)

Henn, Johannes M. [PRISMA Cluster of Excellence, Johannes Gutenberg Universität Mainz,55099 Mainz (Germany); Kavli Institute for Theoretical Physics, UC Santa Barbara,Santa Barbara (United States); Smirnov, Alexander V. [Research Computing Center, Moscow State University,119992 Moscow (Russian Federation); Smirnov, Vladimir A. [Skobeltsyn Institute of Nuclear Physics of Moscow State University,119992 Moscow (Russian Federation); Institut für Theoretische Teilchenphysik, Karlsruhe Institute of Technology (KIT),76128 Karlsruhe (Germany)

2016-12-28

We use the method of differential equations to analytically evaluate all planar three-loop Feynman integrals relevant for form factor calculations involving massive particles. Our results for ninety master integrals at general q{sup 2} are expressed in terms of multiple polylogarithms, and results for fiftyone master integrals at the threshold q{sup 2}=4m{sup 2} are expressed in terms of multiple polylogarithms of argument one, with indices equal to zero or to a sixth root of unity.

On loop extensions and cohomology of loops

OpenAIRE

Benítez, Rolando Jiménez; Meléndez, Quitzeh Morales

2015-01-01

In this paper are defined cohomology-like groups that classify loop extensions satisfying a given identity in three variables for association identities, and in two variables for the case of commutativity. It is considered a large amount of identities. This groups generalize those defined in works of Nishigori [2] and of Jhonson and Leedham-Green [4]. It is computed the number of metacyclic extensions for trivial action of the quotient on the kernel in one particular case for left Bol loops a...

An evaluation of multiple annealing and looping based genome amplification using a synthetic bacterial community

KAUST Repository

Wang, Yong

2016-02-23

The low biomass in environmental samples is a major challenge for microbial metagenomic studies. The amplification of a genomic DNA was frequently applied to meeting the minimum requirement of the DNA for a high-throughput next-generation-sequencing technology. Using a synthetic bacterial community, the amplification efficiency of the Multiple Annealing and Looping Based Amplification Cycles (MALBAC) kit that is originally developed to amplify the single-cell genomic DNA of mammalian organisms is examined. The DNA template of 10 pg in each reaction of the MALBAC amplification may generate enough DNA for Illumina sequencing. Using 10 pg and 100 pg templates for each reaction set, the MALBAC kit shows a stable and homogeneous amplification as indicated by the highly consistent coverage of the reads from the two amplified samples on the contigs assembled by the original unamplified sample. Although GenomePlex whole genome amplification kit allows one to generate enough DNA using 100 pg of template in each reaction, the minority of the mixed bacterial species is not linearly amplified. For both of the kits, the GC-rich regions of the genomic DNA are not efficiently amplified as suggested by the low coverage of the contigs with the high GC content. The high efficiency of the MALBAC kit is supported for the amplification of environmental microbial DNA samples, and the concerns on its application are also raised to bacterial species with the high GC content.

Advancements Made to the Wingman Software-in-the-Loop (SIL) Simulation: How to Operate the SIL

Science.gov (United States)

2017-12-01

then comparing the positions in the simulation . This required going through the mesh generation and conversion process multiple times. b. One of the...ARL-TR-8254 ● DEC 2017 US Army Research Laboratory Advancements Made to the Wingman Software-in-the-Loop (SIL) Simulation : How...TR-8254 ● DEC 2017 US Army Research Laboratory Advancements Made to the Wingman Software-in-the-Loop (SIL) Simulation : How to Operate the SIL

Size asymmetry in intraspecific competition and the density-dependence of inbreeding depression in a natural plant population: a case study in cassava (Manihot esculenta Crantz, Euphorbiaceae).

Science.gov (United States)

Pujol, B; McKey, D

2006-01-01

The effects of competition on the genetic composition of natural populations are not well understood. We combined demography and molecular genetics to study how intraspecific competition affects microevolution in cohorts of volunteer plants of cassava (Manihot esculenta) originating from seeds in slash-and-burn fields of Palikur Amerindians in French Guiana. In this clonally propagated crop, genotypic diversity is enhanced by the incorporation of volunteer plants into farmers' stocks of clonal propagules. Mortality of volunteer plants was density-dependent. Furthermore, the size asymmetry of intraspecific competition increased with local clustering of plants. Size of plants was correlated with their multilocus heterozygosity, and stronger size-dependence of survival in clusters of plants, compared with solitary plants, increased the magnitude of inbreeding depression when competition was severe. The density-dependence of inbreeding depression of volunteer plants helps explain the high heterozygosity of volunteers that survive to harvest time and thus become candidates for clonal propagation. This effect could help favour the maintenance of sex in this 'vegetatively' propagated crop plant.

Rapid Simulation of Flat Knitting Loops Based On the Yarn Texture and Loop Geometrical Model

Directory of Open Access Journals (Sweden)

Lu Zhiwen

2017-06-01

Full Text Available In order to create realistic loop primitives suitable for the fast computer-aided design (CAD of the flat knitted fabric, we have a research on the geometric model of the loop as well as the variation of the loop surface. Establish the texture variation model based on the changing process from the normal yarn to loop that provides the realistic texture of the simulative loop. Then optimize the simulative loop based on illumination variation. This paper develops the computer program with the optimization algorithm and achieves the loop simulation of different yarns to verify the feasibility of the proposed algorithm. Our work provides a fast CAD of the flat knitted fabric with loop simulation, and it is not only more realistic but also material adjustable. Meanwhile it also provides theoretical value for the flat knitted fabric computer simulation.

Remnant Pachira quinata pasture trees have greater opportunities to self and suffer reduced reproductive success due to inbreeding depression.

Science.gov (United States)

Rymer, P D; Sandiford, M; Harris, S A; Billingham, M R; Boshier, D H

2015-08-01

Habitat fragmentation is extensive throughout the world, converting natural ecosystems into fragments of varying size, density and connectivity. The potential value of remnant trees in agricultural landscapes as seed sources and in connecting fragments has formed a fertile area of debate. This study contrasted the mating patterns of bat-pollinated Pachira quinata trees in a continuous forest to those in pasture through microsatellite-based paternity analysis of progeny. The breeding system was determined by analysis of pollen tube growth and seed production from controlled pollinations. Fitness of selfed and outcrossed seed was compared by germination and seedling growth. There was more inbreeding within pasture trees (outcrossing=0.828±0.015) compared with forest trees (0.926±0.005). Pasture trees had fewer sires contributing to mating events, but pollen dispersal distances were greater than those in the forest. Paternity analysis showed variation in outcrossing rates among pasture trees with high proportions of external and self pollen sources detected. A leaky self-incompatibility system was found, with self pollen having reduced germination on stigmas and slower growth rate through the style. Controlled pollinations also showed a varied ability to self among trees, which was reflected in the selfing rates among pasture trees shown by the paternity analysis (0-80% selfing). Self pollination resulted in lower seed set, germination and seedling growth compared with outcrossing. While remnant trees in agricultural landscapes are involved in broader mating patterns, they show increased but varied levels of inbreeding, which result in reduced fitness.

Technology transfer of operator-in-the-loop simulation

Science.gov (United States)

Yae, K. H.; Lin, H. C.; Lin, T. C.; Frisch, H. P.

1994-01-01

The technology developed for operator-in-the-loop simulation in space teleoperation has been applied to Caterpillar's backhoe, wheel loader, and off-highway truck. On an SGI workstation, the simulation integrates computer modeling of kinematics and dynamics, real-time computational and visualization, and an interface with the operator through the operator's console. The console is interfaced with the workstation through an IBM-PC in which the operator's commands were digitized and sent through an RS-232 serial port. The simulation gave visual feedback adequate for the operator in the loop, with the camera's field of vision projected on a large screen in multiple view windows. The view control can emulate either stationary or moving cameras. This simulator created an innovative engineering design environment by integrating computer software and hardware with the human operator's interactions. The backhoe simulation has been adopted by Caterpillar in building a virtual reality tool for backhoe design.

Multi-Evaporator Miniature Loop Heat Pipe for Small Spacecraft Thermal Control. Part 1; New Technologies and Validation Approach

Science.gov (United States)

Ku, Jentung; Ottenstein, Laura; Douglas, Donya; Hoang, Triem

2010-01-01

Under NASA s New Millennium Program Space Technology 8 (ST 8) Project, four experiments Thermal Loop, Dependable Microprocessor, SAILMAST, and UltraFlex - were conducted to advance the maturity of individual technologies from proof of concept to prototype demonstration in a relevant environment , i.e. from a technology readiness level (TRL) of 3 to a level of 6. This paper presents the new technologies and validation approach of the Thermal Loop experiment. The Thermal Loop is an advanced thermal control system consisting of a miniature loop heat pipe (MLHP) with multiple evaporators and multiple condensers designed for future small system applications requiring low mass, low power, and compactness. The MLHP retains all features of state-of-the-art loop heat pipes (LHPs) and offers additional advantages to enhance the functionality, performance, versatility, and reliability of the system. Details of the thermal loop concept, technical advances, benefits, objectives, level 1 requirements, and performance characteristics are described. Also included in the paper are descriptions of the test articles and mathematical modeling used for the technology validation. An MLHP breadboard was built and tested in the laboratory and thermal vacuum environments for TRL 4 and TRL 5 validations, and an MLHP proto-flight unit was built and tested in a thermal vacuum chamber for the TRL 6 validation. In addition, an analytical model was developed to simulate the steady state and transient behaviors of the MLHP during various validation tests. Capabilities and limitations of the analytical model are also addressed.

FORWARD MODELING OF STANDING KINK MODES IN CORONAL LOOPS. II. APPLICATIONS

Energy Technology Data Exchange (ETDEWEB)

Yuan, Ding; Doorsselaere, Tom Van, E-mail: DYuan2@uclan.ac.uk [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B bus 2400, B-3001 Leuven (Belgium)

2016-04-15

Magnetohydrodynamic waves are believed to play a significant role in coronal heating, and could be used for remote diagnostics of solar plasma. Both the heating and diagnostic applications rely on a correct inversion (or backward modeling) of the observables into the thermal and magnetic structures of the plasma. However, due to the limited availability of observables, this is an ill-posed issue. Forward modeling is designed to establish a plausible mapping of plasma structuring into observables. In this study, we set up forward models of standing kink modes in coronal loops and simulate optically thin emissions in the extreme ultraviolet bandpasses, and then adjust plasma parameters and viewing angles to match three events of transverse loop oscillations observed by the Solar Dynamics Observatory/Atmospheric Imaging Assembly. We demonstrate that forward models could be effectively used to identify the oscillation overtone and polarization, to reproduce the general profile of oscillation amplitude and phase, and to predict multiple harmonic periodicities in the associated emission intensity and loop width variation.

Multiple roles of mobile active center loops in the E1 component of the Escherichia coli pyruvate dehydrogenase complex - Linkage of protein dynamics to catalysis

Science.gov (United States)

Jordan, Frank; Arjunan, Palaniappa; Kale, Sachin; Nemeria, Natalia S.; Furey, William

2009-01-01

The region encompassing residues 401–413 on the E1 component of the pyruvate dehydrogenase multienzyme complex from Escherichia coli comprises a loop (the inner loop) which was not seen in the X-ray structure in the presence of thiamin diphosphate, the required cofactor for the enzyme. This loop is seen in the presence of a stable analogue of the pre-decarboxylation intermediate, the covalent adduct between the substrate analogue methyl acetylphosphonate and thiamin diphosphate, C2α-phosphonolactylthiamin diphosphate. It has been shown that the residue H407 and several other residues on this loop are required to reduce the mobility of the loop so electron density corresponding to it can be seen once the pre-decarboxylation intermediate is formed. Concomitantly, the loop encompassing residues 541–557 (the outer loop) appears to work in tandem with the inner loop and there is a hydrogen bond between the two loops ensuring their correlated motion. The inner loop was shown to: a) sequester the active center from carboligase side reactions; b) assist the interaction between the E1 and the E2 components, thereby affecting the overall reaction rate of the entire multienzyme complex; c) control substrate access to the active center. Using viscosity effects on kinetics it was shown that formation of the pre-decarboxylation intermediate is specifically affected by loop movement. A cysteine-less variant was created for the E1 component, onto which cysteines were substituted at selected loop positions. Introducing an electron spin resonance spin label and an 19F NMR label onto these engineered cysteines, the loop mobility was examined: a) both methods suggested that in the absence of ligand, the loop exists in two conformations; b) line-shape analysis of the NMR signal at different temperatures, enabled estimation of the rate constant for loop movement, and this rate constant was found to be of the same order of magnitude as the turnover number for the enzyme under the

Orbits in elementary, power-law galaxy bars - 1. Occurrence and role of single loops

Science.gov (United States)

Struck, Curtis

2018-05-01

Orbits in galaxy bars are generally complex, but simple closed loop orbits play an important role in our conceptual understanding of bars. Such orbits are found in some well-studied potentials, provide a simple model of the bar in themselves, and may generate complex orbit families. The precessing, power ellipse (p-ellipse) orbit approximation provides accurate analytic orbit fits in symmetric galaxy potentials. It remains useful for finding and fitting simple loop orbits in the frame of a rotating bar with bar-like and symmetric power-law potentials. Second-order perturbation theory yields two or fewer simple loop solutions in these potentials. Numerical integrations in the parameter space neighbourhood of perturbation solutions reveal zero or one actual loops in a range of such potentials with rising rotation curves. These loops are embedded in a small parameter region of similar, but librating orbits, which have a subharmonic frequency superimposed on the basic loop. These loops and their librating companions support annular bars. Solid bars can be produced in more complex potentials, as shown by an example with power-law indices varying with radius. The power-law potentials can be viewed as the elementary constituents of more complex potentials. Numerical integrations also reveal interesting classes of orbits with multiple loops. In two-dimensional, self-gravitating bars, with power-law potentials, single-loop orbits are very rare. This result suggests that gas bars or oval distortions are unlikely to be long-lived, and that complex orbits or three-dimensional structure must support self-gravitating stellar bars.

Random walk loop soup

OpenAIRE

Lawler, Gregory F.; Ferreras, José A. Trujillo

2004-01-01

The Brownian loop soup introduced in Lawler and Werner (2004) is a Poissonian realization from a sigma-finite measure on unrooted loops. This measure satisfies both conformal invariance and a restriction property. In this paper, we define a random walk loop soup and show that it converges to the Brownian loop soup. In fact, we give a strong approximation result making use of the strong approximation result of Koml\\'os, Major, and Tusn\\'ady. To make the paper self-contained, we include a proof...

Importance of the extracellular loops in G protein-coupled receptors for ligand recognition and receptor activation.

Science.gov (United States)

Peeters, M C; van Westen, G J P; Li, Q; IJzerman, A P

2011-01-01

G protein-coupled receptors (GPCRs) are the major drug target of medicines on the market today. Therefore, much research is and has been devoted to the elucidation of the function and three-dimensional structure of this large family of membrane proteins, which includes multiple conserved transmembrane domains connected by intra- and extracellular loops. In the last few years, the less conserved extracellular loops have garnered increasing interest, particularly after the publication of several GPCR crystal structures that clearly show the extracellular loops to be involved in ligand binding. This review will summarize the recent progress made in the clarification of the ligand binding and activation mechanism of class-A GPCRs and the role of extracellular loops in this process. Copyright © 2010 Elsevier Ltd. All rights reserved.

Neutron transport in irradiation loops (IRENE loop)

International Nuclear Information System (INIS)

Sarsam, Maher.

1980-09-01

This thesis is composed of two parts with different aspects. Part one is a technical description of the loop and its main ancillary facilities as well as of the safety and operational regulations. The measurement methods on the model of the ISIS reactor and on the loop in the OSIRIS reactor are described. Part two deals with the possibility of calculating the powers dissipated by each rod of the fuel cluster, using appropriate computer codes, not only in the reflector but also in the core and to suggest a method of calculation [fr

The loop of Henle as the milestone of mammalian kindey concentrating ability: a historical review.

Science.gov (United States)

Koulouridis, Efstathios; Koulouridis, Ioannis

2014-01-01

The first description of the renal tubules is attributed to Lorenzo Bellini in 1662 and four years later Marcello Malpighi described the glomerulus. In 1842 Sir William Bowman described the capsule that surrounds the Malpighian body and its connection with the renal tubule and introduced the "excretory" hypothesis of urine formation. In the same year, Carl Ludwig introduced the "filtration-reabsorption" hypothesis of urine formation. Bowman's hypothesis was accepted by the so-called "vitalists" and Ludwig's hypothesis by the so-called "mechanists". In the middle of this confliction, Jacob Henle described in 1862 the homonymous "U" shaped loop but his discovery has neglected. In 1942 Werner Kuhn, a physical chemist, proposed that the loop of Henle may be the natural analog of the hairpin countercurrent multiplication system which concentrates urine in mammalian kidneys. In 1951 Kuhn, Hargitay and Wirz showed experimentally that the loop of Henle was the most important part of the countercurrent multiplication system of urine-concentrating mechanism in mammalian kidneys. The new theory was accepted by English-speaking scientists later, in 1958, when Carl Gottschalk and Margaret Mylle published their experimental work and proved that Kuhn's theory was correct. Gottschalk summarized the evidence of the accumulated knowledge in 1962, three centuries after the first description of renal tubules and one century after description of Henle's loop.

Loop space representation of quantum general relativity and the group of loops

International Nuclear Information System (INIS)

Gambini, R.

1991-01-01

The action of the constraints of quantum general relativity on a general state in the loop representation is coded in terms of loop derivatives. These differential operators are related to the infinitesimal generators of the group of loops and generalize the area derivative first considered by Mandelstam. A new sector of solutions of the physical states space of nonperturbative quantum general relativity is found. (orig.)

Fermions and loops on graphs: I. Loop calculus for determinants

International Nuclear Information System (INIS)

Chernyak, Vladimir Y; Chertkov, Michael

2008-01-01

This paper is the first in a series devoted to evaluation of the partition function in statistical models on graphs with loops in terms of the Berezin/fermion integrals. The paper focuses on a representation of the determinant of a square matrix in terms of a finite series, where each term corresponds to a loop on the graph. The representation is based on a fermion version of the loop calculus, previously introduced by the authors for graphical models with finite alphabets. Our construction contains two levels. First, we represent the determinant in terms of an integral over anti-commuting Grassmann variables, with some reparametrization/gauge freedom hidden in the formulation. Second, we show that a special choice of the gauge, called the BP (Bethe–Peierls or belief propagation) gauge, yields the desired loop representation. The set of gauge fixing BP conditions is equivalent to the Gaussian BP equations, discussed in the past as efficient (linear scaling) heuristics for estimating the covariance of a sparse positive matrix

Expanding and Contracting Coronal Loops as Evidence of Vortex Flows Induced by Solar Eruptions

Energy Technology Data Exchange (ETDEWEB)

Dudík, J. [Astronomical Institute of the Czech Academy of Sciences, Fričova 298, 251 65 Ondřejov (Czech Republic); Zuccarello, F. P.; Aulanier, G.; Schmieder, B.; Démoulin, P., E-mail: jaroslav.dudik@asu.cas.cz [LESIA, Observatoire de Paris, Psl Research University, CNRS, Sorbonne Universits, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cit, 5 place Jules Janssen, F-92195 Meudon (France)

2017-07-20

Eruptive solar flares were predicted to generate large-scale vortex flows at both sides of the erupting magnetic flux rope. This process is analogous to a well-known hydrodynamic process creating vortex rings. The vortices lead to advection of closed coronal loops located at the peripheries of the flaring active region. Outward flows are expected in the upper part and returning flows in the lower part of the vortex. Here, we examine two eruptive solar flares, the X1.1-class flare SOL2012-03-05T03:20 and the C3.5-class SOL2013-06-19T07:29. In both flares, we find that the coronal loops observed by the Atmospheric Imaging Assembly in its 171 Å, 193 Å, or 211 Å passbands show coexistence of expanding and contracting motions, in accordance with the model prediction. In the X-class flare, multiple expanding and contracting loops coexist for more than 35 minutes, while in the C-class flare, an expanding loop in 193 Å appears to be close by and cotemporal with an apparently imploding loop arcade seen in 171 Å. Later, the 193 Å loop also switches to contraction. These observations are naturally explained by vortex flows present in a model of eruptive solar flares.

Dechanneling by dislocation loops

International Nuclear Information System (INIS)

Chalant, Gerard.

1976-09-01

Ion implantation always induces the creation of dislocation loops. When the damage profile is determined by a backscattering technique, the dechanneling by these loops is implicitely at the origin of these measurements. The dechanneling of alpha particles by dislocation loops produced by the coalescence of quenched-in vacancies in aluminium is studied. The dechanneling and the concentration of loops were determined simultaneously. The dechanneling width around dislocation was found equal to lambda=6A, both for perfect and imperfect loops having a mean diameter d=250A. In the latter case, a dechanneling probability chi=0.34 was determined for the stacking fault, in good agreement with previous determination in gold. A general formula is proposed which takes into account the variation of lambda with the curvature (or the diameter d) of the loops. Finally, by a series of isothermal anneals, the self-diffusion energy ΔH of aluminium was measured. The value obtained ΔH=1.32+-0.10eV is in good agreement with the values obtained by other methods [fr

String-inspired BCJ numerators for one-loop MHV amplitudes

International Nuclear Information System (INIS)

He, Song; Monteiro, Ricardo; Schlotterer, Oliver

2016-01-01

We find simple expressions for the kinematic numerators of one-loop MHV amplitudes in maximally supersymmetric Yang-Mills theory and supergravity, at any multiplicity. The gauge-theory numerators satisfy the Bern-Carrasco-Johansson (BCJ) duality between color and kinematics, so that the gravity numerators are simply the square of the gauge-theory ones. The duality holds because the numerators can be written in terms of structure constants of a kinematic algebra, which is familiar from the BCJ organization of self-dual gauge theory and gravity. The close connection that we find between one-loop amplitudes in the self-dual case and in the maximally supersymmetric case is reminiscent of the dimension-shifting formula. The starting point for arriving at our expressions is the dimensional reduction of ten-dimensional amplitudes obtained in the field-theory limit of open superstrings.

Three-Dimensional Printing of Vitrification Loop Prototypes for Aquatic Species.

Science.gov (United States)

Tiersch, Nolan J; Childress, William M; Tiersch, Terrence R

2018-05-16

Vitrification is a method of cryopreservation that freezes samples rapidly, while forming an amorphous solid ("glass"), typically in small (μL) volumes. The goal of this project was to create, by three-dimensional (3D) printing, open vitrification devices based on an elliptical loop that could be efficiently used and stored. Vitrification efforts can benefit from the application of 3D printing, and to begin integration of this technology, we addressed four main variables: thermoplastic filament type, loop length, loop height, and method of loading. Our objectives were to: (1) design vitrification loops with varied dimensions; (2) print prototype loops for testing; (3) evaluate loading methods for the devices; and (4) classify vitrification responses to multiple device configurations. The various configurations were designed digitally using 3D CAD (Computer Aided Design) software, and prototype devices were produced with MakerBot ® 3D printers. The thermoplastic filaments used to produce devices were acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Vitrification devices were characterized by the film volumes formed with different methods of loading (pipetting or submersion). Frozen films were classified to determine vitrification quality: zero (opaque, or abundant crystalline ice formation); one (translucent, or partial vitrification), or two (transparent, or substantial vitrification, glass). A published vitrification solution was used to conduct experiments. Loading by pipetting formed frozen films more reliably than by submersion, but submersion yielded fewer filling problems and was more rapid. The loop designs that yielded the highest levels of vitrification enabled rapid transfer of heat, and most often were characterized as being longer and consisting of fewer layers (height). 3D printing can assist standardization of vitrification methods and research, yet can also provide the ability to quickly design and fabricate custom devices when

Smith predictor-based multiple periodic disturbance compensation for long dead-time processes

Science.gov (United States)

Tan, Fang; Li, Han-Xiong; Shen, Ping

2018-05-01

Many disturbance rejection methods have been proposed for processes with dead-time, while these existing methods may not work well under multiple periodic disturbances. In this paper, a multiple periodic disturbance rejection is proposed under the Smith predictor configuration for processes with long dead-time. One feedback loop is added to compensate periodic disturbance while retaining the advantage of the Smith predictor. With information of the disturbance spectrum, the added feedback loop can remove multiple periodic disturbances effectively. The robust stability can be easily maintained through the rigorous analysis. Finally, simulation examples demonstrate the effectiveness and robustness of the proposed method for processes with long dead-time.

The Brownian loop soup

OpenAIRE

Lawler, Gregory F.; Werner, Wendelin

2003-01-01

We define a natural conformally invariant measure on unrooted Brownian loops in the plane and study some of its properties. We relate this measure to a measure on loops rooted at a boundary point of a domain and show how this relation gives a way to ``chronologically add Brownian loops'' to simple curves in the plane.

Advanced multi-evaporator loop thermosyphon

International Nuclear Information System (INIS)

Mameli, M.; Mangini, D.; Vanoli, G.F.T.; Araneo, L.; Filippeschi, S.; Marengo, M.

2016-01-01

A novel prototype of multi-evaporator closed loop thermosyphon is designed and tested at different heaters position, inclinations and heat input levels, in order to prove that a peculiar arrangement of multiple heaters may be used in order to enhance the flow motion and consequently the thermal performance. The device consists in an aluminum tube (Inner/Outer tube diameter 3.0 mm/5.0 mm), bent into a planar serpentine with five U-turns and partially filled with FC-72, 50% vol. The evaporator zone is equipped with five heated patches (one for each U-turn) in series with respect to the flow path. In the first arrangement, heaters are wrapped on each bend symmetrically, while in the second layout heaters are located on the branch just above the U-turn, non-symmetrical with respect to the gravity direction, in order to promote the fluid circulation in a preferential direction. The condenser zone is cooled by forced air and equipped with a 50 mm transparent section for the flow pattern visualization. The non-symmetrical heater arrangement effectively promotes a stable fluid circulation and a reliable operation for a wider range of heat input levels and orientations with respect to the symmetrical case. In vertical position, the heat flux dissipation exceeds the pool boiling heat transfer limit for FC-72 by 75% and the tube wall temperatures in the evaporator zone are kept lower than 80 °C. Furthermore, the heat flux capability is up to five times larger with respect to the other existing wickless heat pipe technologies demonstrating the attractiveness of the new concept for electronic cooling thermal management. - Highlights: • A novel passive heat transfer device named Multi-Evaporator Loop Thermosyphon is tested. • The loop is investigated at different heating patterns, inclinations and heat power levels. • The non-symmetrical heating configuration promotes the fluid circulation within the loop. • The performance in terms of maximum heat flux exceeds the

Reactor recirculation pump test loop

International Nuclear Information System (INIS)

Taka, Shusei; Kato, Hiroyuki

1979-01-01

A test loop for a reactor primary loop recirculation pumps (PLR pumps) has been constructed at Ebara's Haneda Plant in preparation for production of PLR pumps under license from Byron Jackson Pump Division of Borg-Warner Corporation. This loop can simulate operating conditions for test PLR pumps with 130 per cent of the capacity of pumps for a 1100 MWe BWR plant. A main loop, primary cooling system, water demineralizer, secondary cooling system, instrumentation and control equipment and an electric power supply system make up the test loop. This article describes the test loop itself and test results of two PLR pumps for Fukushima No. 2 N.P.S. Unit 1 and one main circulation pump for HAZ Demonstration Test Facility. (author)

Disruption of endosperm development: an inbreeding effect in almond (Prunus dulcis).

Science.gov (United States)

Ortega, Encarnación; Martínez-García, Pedro J; Dicenta, Federico; Egea, José

2010-06-01

A homozygous self-compatible almond, originated from self-fertilization of a self-compatible genotype and producing a reasonable yield following open pollination, exhibited a very high fruit drop rate when self-pollinated. To investigate whether fruit dropping in this individual is related to an abnormal development of the embryo sac following self-fertilization, histological sections of ovaries from self and cross-pollinated flowers were observed by light microscopy. Additionally, the presence of pollen tubes in the ovary and fruit set were determined for both types of pollination. Despite pollen tubes reached the ovary after both pollinations, differences in embryo sac and endosperm development after fertilization were found. Thus, while for cross-fertilized ovules a pro-embryo and an endosperm with abundant nuclei were generally observed, most self-fertilized ovules remained in a previous developmental stage in which the embryo sac was not elongated and endosperm nuclei were absent. Although 30 days after pollination fruit set was similar for both pollination types, at 60 days it was significantly reduced for self-pollination. These results provide evidence that the high fruit drop in this genotype is the consequence of a disrupted development of the endosperm, what could be an expression of its high level of inbreeding.

Wilson loops in minimal surfaces

International Nuclear Information System (INIS)

Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

1999-01-01

The AdS/CFT correspondence suggests that the Wilson loop of the large N gauge theory with N = 4 supersymmetry in 4 dimensions is described by a minimal surface in AdS 5 x S 5 . The authors examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which the authors call BPS loops, whose expectation values are free from ultra-violet divergence. They formulate the loop equation for such loops. To the extent that they have checked, the minimal surface in AdS 5 x S 5 gives a solution of the equation. The authors also discuss the zig-zag symmetry of the loop operator. In the N = 4 gauge theory, they expect the zig-zag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. They will show how this is realized for the minimal surface

Wilson loops and minimal surfaces

International Nuclear Information System (INIS)

Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

1999-01-01

The AdS-CFT correspondence suggests that the Wilson loop of the large N gauge theory with N=4 supersymmetry in four dimensions is described by a minimal surface in AdS 5 xS 5 . We examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which we call BPS loops, whose expectation values are free from ultraviolet divergence. We formulate the loop equation for such loops. To the extent that we have checked, the minimal surface in AdS 5 xS 5 gives a solution of the equation. We also discuss the zigzag symmetry of the loop operator. In the N=4 gauge theory, we expect the zigzag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. We will show how this is realized for the minimal surface. (c) 1999 The American Physical Society

Advanced ECCD based NTM control in closed-loop operation at ASDEX Upgrade (AUG)

Science.gov (United States)

Reich, Matthias; Barrera-Orte, Laura; Behler, Karl; Bock, Alexander; Giannone, Louis; Maraschek, Marc; Poli, Emanuele; Rapson, Chris; Stober, Jörg; Treutterer, Wolfgang

2012-10-01

In high performance plasmas, Neoclassical Tearing Modes (NTMs) are regularly observed at reactor-grade beta-values. They limit the achievable normalized beta, which is undesirable because fusion performance scales as beta squared. The method of choice for controlling and avoiding NTMs at AUG is the deposition of ECCD inside the magnetic island for stabilization in real-time (rt). Our approach to tackling such complex control problems using real-time diagnostics allows rigorous optimization of all subsystems. Recent progress in rt-equilibrium reconstruction (< 3.5 ms), rt-localization of NTMs (< 8 ms) and rt beam tracing (< 25 ms) allows closed-loop feedback operation using multiple movable mirrors as the ECCD deposition actuator. The rt-equilibrium uses function parametrization or a fast Grad-Shafranov solver with an option to include rt-MSE measurements. The island localization is based on a correlation of ECE and filtered Mirnov signals. The rt beam-tracing module provides deposition locations and their derivative versus actuator position of multiple gyrotrons. The ``MHD controller'' finally drives the actuators. Results utilizing closed-loop operation with multiple gyrotrons and their effect on NTMs are shown.

A Switching Anti-windup Design Using Multiple Lyapunov Functions

NARCIS (Netherlands)

Lu, L.; Lin, Z.; Chen, J.

2009-01-01

This paper proposes a switching anti-windup design, which aims to enlarge the domain of attraction of the closed-loop system. Multiple anti-windup gains along with an index function that orchestrates the switching among these anti-windup gains are designed based on the min function of multiple

THE ROLE OF KELVIN–HELMHOLTZ INSTABILITY FOR PRODUCING LOOP-TOP HARD X-RAY SOURCES IN SOLAR FLARES

Energy Technology Data Exchange (ETDEWEB)

Fang, Xia; Yuan, Ding; Xia, Chun; Doorsselaere, Tom Van; Keppens, Rony [Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, 3001 Leuven (Belgium)

2016-12-10

We propose a model for the formation of loop-top hard X-ray (HXR) sources in solar flares through the inverse Compton mechanism, scattering the surrounding soft X-ray (SXR) photons to higher energy HXR photons. We simulate the consequences of a flare-driven energy deposit in the upper chromosphere in the impulsive phase of single loop flares. The consequent chromosphere evaporation flows from both footpoints reach speeds up to hundreds of kilometers per second, and we demonstrate how this triggers Kelvin–Helmholtz instability (KHI) in the loop top, under mildly asymmetric conditions, or more toward the loop flank for strongly asymmetric cases. The KHI vortices further fragment the magnetic topology into multiple magnetic islands and current sheets, and the hot plasma within leads to a bright loop-top SXR source region. We argue that the magnetohydrodynamic turbulence that appears at the loop apex could be an efficient accelerator of non-thermal particles, which the island structures can trap at the loop-top. These accelerated non-thermal particles can upscatter the surrounding thermal SXR photons emitted by the extremely hot evaporated plasma to HXR photons.

BPS Wilson loops and Bremsstrahlung function in ABJ(M): a two loop analysis

Energy Technology Data Exchange (ETDEWEB)

Bianchi, Marco S. [Institut für Physik, Humboldt-Universität zu Berlin,Newtonstraße 15, 12489 Berlin (Germany); Griguolo, Luca [Dipartimento di Fisica e Scienze della Terra, Università di Parmaand INFN Gruppo Collegato di Parma,Viale G.P. Usberti 7/A, 43100 Parma (Italy); Leoni, Matias [Physics Department, FCEyN-UBA & IFIBA-CONICETCiudad Universitaria, Pabellón I, 1428, Buenos Aires (Argentina); Penati, Silvia [Dipartimento di Fisica, Università di Milano-Bicoccaand INFN, Sezione di Milano-Bicocca,Piazza della Scienza 3, I-20126 Milano (Italy); Seminara, Domenico [Dipartimento di Fisica, Università di Firenzeand INFN Sezione di Firenze,via G. Sansone 1, 50019 Sesto Fiorentino (Italy)

2014-06-19

We study a family of circular BPS Wilson loops in N=6 super Chern-Simons-matter theories, generalizing the usual 1/2-BPS circle. The scalar and fermionic couplings depend on two deformation parameters and these operators can be considered as the ABJ(M) counterpart of the DGRT latitudes defined in N=4 SYM. We perform a complete two-loop analysis of their vacuum expectation value, discuss the appearance of framing-like phases and propose a general relation with cohomologically equivalent bosonic operators. We make an all-loop proposal for computing the Bremsstrahlung function associated to the 1/2-BPS cusp in terms of these generalized Wilson loops. When applied to our two-loop result it reproduces the known expression. Finally, we comment on the generalization of this proposal to the bosonic 1/6-BPS case.

Low genetic diversity despite multiple introductions of the invasive plant species Impatiens glandulifera in Europe.

Science.gov (United States)

Hagenblad, Jenny; Hülskötter, Jennifer; Acharya, Kamal Prasad; Brunet, Jörg; Chabrerie, Olivier; Cousins, Sara A O; Dar, Pervaiz A; Diekmann, Martin; De Frenne, Pieter; Hermy, Martin; Jamoneau, Aurélien; Kolb, Annette; Lemke, Isgard; Plue, Jan; Reshi, Zafar A; Graae, Bente Jessen

2015-08-20

Invasive species can be a major threat to native biodiversity and the number of invasive plant species is increasing across the globe. Population genetic studies of invasive species can provide key insights into their invasion history and ensuing evolution, but also for their control. Here we genetically characterise populations of Impatiens glandulifera, an invasive plant in Europe that can have a major impact on native plant communities. We compared populations from the species' native range in Kashmir, India, to those in its invaded range, along a latitudinal gradient in Europe. For comparison, the results from 39 other studies of genetic diversity in invasive species were collated. Our results suggest that I. glandulifera was established in the wild in Europe at least twice, from an area outside of our Kashmir study area. Our results further revealed that the genetic diversity in invasive populations of I. glandulifera is unusually low compared to native populations, in particular when compared to other invasive species. Genetic drift rather than mutation seems to have played a role in differentiating populations in Europe. We find evidence of limitations to local gene flow after introduction to Europe, but somewhat less restrictions in the native range. I. glandulifera populations with significant inbreeding were only found in the species' native range and invasive species in general showed no increase in inbreeding upon leaving their native ranges. In Europe we detect cases of migration between distantly located populations. Human activities therefore seem to, at least partially, have facilitated not only introductions, but also further spread of I. glandulifera across Europe. Although multiple introductions will facilitate the retention of genetic diversity in invasive ranges, widespread invasive species can remain genetically relatively invariant also after multiple introductions. Phenotypic plasticity may therefore be an important component of the

A strategy analysis for genetic association studies with known inbreeding

Directory of Open Access Journals (Sweden)

del Giacco Stefano

2011-07-01

Full Text Available Abstract Background Association studies consist in identifying the genetic variants which are related to a specific disease through the use of statistical multiple hypothesis testing or segregation analysis in pedigrees. This type of studies has been very successful in the case of Mendelian monogenic disorders while it has been less successful in identifying genetic variants related to complex diseases where the insurgence depends on the interactions between different genes and the environment. The current technology allows to genotype more than a million of markers and this number has been rapidly increasing in the last years with the imputation based on templates sets and whole genome sequencing. This type of data introduces a great amount of noise in the statistical analysis and usually requires a great number of samples. Current methods seldom take into account gene-gene and gene-environment interactions which are fundamental especially in complex diseases. In this paper we propose to use a non-parametric additive model to detect the genetic variants related to diseases which accounts for interactions of unknown order. Although this is not new to the current literature, we show that in an isolated population, where the most related subjects share also most of their genetic code, the use of additive models may be improved if the available genealogical tree is taken into account. Specifically, we form a sample of cases and controls with the highest inbreeding by means of the Hungarian method, and estimate the set of genes/environmental variables, associated with the disease, by means of Random Forest. Results We have evidence, from statistical theory, simulations and two applications, that we build a suitable procedure to eliminate stratification between cases and controls and that it also has enough precision in identifying genetic variants responsible for a disease. This procedure has been successfully used for the beta-thalassemia, which is

Steam drum level control studies of a natural circulation multi loop reactor

Energy Technology Data Exchange (ETDEWEB)

Kumar, Rajesh; Contractor, A.D.; Srivastava, Abhishek; Lele, H.G. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Safety Div.; Vaze, K.K. [Bhabha Atomic Research Centre, Trombay, Mumbai (India). Reactor Design and Development Group

2013-12-15

The proposed heavy water moderated and light water cooled pressure tube type boiling water reactor works on natural circulation at all power levels. It has parallel inter-connected loops with 452 boiling channels in the main heat transport system configuration. These multiple (four) interconnected loops influence the steam drum level control adversely through the common reactor inlet header. Alternate design studies made earlier for efficient control of SD levels have shown favorable results. This has lead to explore further the present scheme with the compartmentalization of CRIH into four compartments catering to four loops separately. The conventional 3-element level control has been found to be working satisfactorily. The interconnections between ECCS header and inlet header compartments have also increased the safety margin for various LOCA and design basis events. The paper deals with the SD level control aspects for this novel MHT configuration which has been analyzed for various PIEs (Postulated Initiating Events) and found to be satisfactory. (orig.)

Phenylnaphthalene Derivatives as Heat Transfer Fluids for Concentrating Solar Power: Loop Experiments and Final Report

Energy Technology Data Exchange (ETDEWEB)

McFarlane, Joanna [ORNL; Bell, Jason R [ORNL; Felde, David K [ORNL; Joseph III, Robert Anthony [ORNL; Qualls, A L [ORNL; Weaver, Samuel P [ORNL

2013-02-01

ORNL and subcontractor Cool Energy completed an investigation of higher-temperature, organic thermal fluids for solar thermal applications. Although static thermal tests showed promising results for 1-phenylnaphthalene, loop testing at temperatures to 450 C showed that the material isomerized at a slow rate. In a loop with a temperature high enough to drive the isomerization, the higher melting point byproducts tended to condense onto cooler surfaces. So, as experienced in loop operation, eventually the internal channels of cooler components such as the waste heat rejection exchanger may become coated or clogged and loop performance will decrease. Thus, pure 1-phenylnaphthalene does not appear to be a fluid that would have a sufficiently long lifetime (years to decades) to be used in a loop at the increased temperatures of interest. Hence a decision was made not to test the ORNL fluid in the loop at Cool Energy Inc. Instead, Cool Energy tested and modeled power conversion from a moderate-temperature solar loop using coupled Stirling engines. Cool Energy analyzed data collected on third and fourth generation SolarHeart Stirling engines operating on a rooftop solar field with a lower temperature (Marlotherm) heat transfer fluid. The operating efficiencies of the Stirling engines were determined at multiple, typical solar conditions, based on data from actual cycle operation. Results highlighted the advantages of inherent thermal energy storage in the power conversion system.

Improving predicted protein loop structure ranking using a Pareto-optimality consensus method.

Science.gov (United States)

Li, Yaohang; Rata, Ionel; Chiu, See-wing; Jakobsson, Eric

2010-07-20

Accurate protein loop structure models are important to understand functions of many proteins. Identifying the native or near-native models by distinguishing them from the misfolded ones is a critical step in protein loop structure prediction. We have developed a Pareto Optimal Consensus (POC) method, which is a consensus model ranking approach to integrate multiple knowledge- or physics-based scoring functions. The procedure of identifying the models of best quality in a model set includes: 1) identifying the models at the Pareto optimal front with respect to a set of scoring functions, and 2) ranking them based on the fuzzy dominance relationship to the rest of the models. We apply the POC method to a large number of decoy sets for loops of 4- to 12-residue in length using a functional space composed of several carefully-selected scoring functions: Rosetta, DOPE, DDFIRE, OPLS-AA, and a triplet backbone dihedral potential developed in our lab. Our computational results show that the sets of Pareto-optimal decoys, which are typically composed of approximately 20% or less of the overall decoys in a set, have a good coverage of the best or near-best decoys in more than 99% of the loop targets. Compared to the individual scoring function yielding best selection accuracy in the decoy sets, the POC method yields 23%, 37%, and 64% less false positives in distinguishing the native conformation, indentifying a near-native model (RMSD Pareto optimality and fuzzy dominance, the POC method is effective in distinguishing the best loop models from the other ones within a loop model set.

Evaluating four-loop conformal Feynman integrals by D-dimensional differential equations

Science.gov (United States)

Eden, Burkhard; Smirnov, Vladimir A.

2016-10-01

We evaluate a four-loop conformal integral, i.e. an integral over four four-dimensional coordinates, by turning to its dimensionally regularized version and applying differential equations for the set of the corresponding 213 master integrals. To solve these linear differential equations we follow the strategy suggested by Henn and switch to a uniformly transcendental basis of master integrals. We find a solution to these equations up to weight eight in terms of multiple polylogarithms. Further, we present an analytical result for the given four-loop conformal integral considered in four-dimensional space-time in terms of single-valued harmonic polylogarithms. As a by-product, we obtain analytical results for all the other 212 master integrals within dimensional regularization, i.e. considered in D dimensions.

Evaluating four-loop conformal Feynman integrals by D-dimensional differential equations

Energy Technology Data Exchange (ETDEWEB)

Eden, Burkhard [Institut für Mathematik und Physik, Humboldt-Universität zu Berlin,Zum großen Windkanal 6, 12489 Berlin (Germany); Smirnov, Vladimir A. [Skobeltsyn Institute of Nuclear Physics, Moscow State University,119992 Moscow (Russian Federation)

2016-10-21

We evaluate a four-loop conformal integral, i.e. an integral over four four-dimensional coordinates, by turning to its dimensionally regularized version and applying differential equations for the set of the corresponding 213 master integrals. To solve these linear differential equations we follow the strategy suggested by Henn and switch to a uniformly transcendental basis of master integrals. We find a solution to these equations up to weight eight in terms of multiple polylogarithms. Further, we present an analytical result for the given four-loop conformal integral considered in four-dimensional space-time in terms of single-valued harmonic polylogarithms. As a by-product, we obtain analytical results for all the other 212 master integrals within dimensional regularization, i.e. considered in D dimensions.

Higher-genus su(N) fusion multiplicities as polytope volumes

International Nuclear Information System (INIS)

Flynn, G; Rasmussen, J; Tahic, M; Walton, M A

2002-01-01

We show how higher-genus su(N) fusion multiplicities may be computed as the discretized volumes of certain polytopes. The method is illustrated by explicit analyses of some su(3) and su(4) fusions, but applies to all higher-point and higher-genus su(N) fusions. It is based on an extension of the realm of Berenstein-Zelevinsky triangles by including so-called gluing and loop-gluing diagrams. The identification of the loop-gluing diagrams is our main new result, since they enable us to characterize higher-genus fusions in terms of polytopes. Also, the genus-2 0-point su(3) fusion multiplicity is found to be a simple binomial coefficient in the affine level

The SH2 domain of Abl kinases regulates kinase autophosphorylation by controlling activation loop accessibility

Science.gov (United States)

Lamontanara, Allan Joaquim; Georgeon, Sandrine; Tria, Giancarlo; Svergun, Dmitri I.; Hantschel, Oliver

2014-11-01

The activity of protein kinases is regulated by multiple molecular mechanisms, and their disruption is a common driver of oncogenesis. A central and almost universal control element of protein kinase activity is the activation loop that utilizes both conformation and phosphorylation status to determine substrate access. In this study, we use recombinant Abl tyrosine kinases and conformation-specific kinase inhibitors to quantitatively analyse structural changes that occur after Abl activation. Allosteric SH2-kinase domain interactions were previously shown to be essential for the leukemogenesis caused by the Bcr-Abl oncoprotein. We find that these allosteric interactions switch the Abl activation loop from a closed to a fully open conformation. This enables the trans-autophosphorylation of the activation loop and requires prior phosphorylation of the SH2-kinase linker. Disruption of the SH2-kinase interaction abolishes activation loop phosphorylation. Our analysis provides a molecular mechanism for the SH2 domain-dependent activation of Abl that may also regulate other tyrosine kinases.

Computational stability appraisal of rectangular natural circulation loop: Effect of loop inclination

International Nuclear Information System (INIS)

Krishnani, Mayur; Basu, Dipankar N.

2017-01-01

Highlights: • Computational model developed for single-phase rectangular natural circulation loop. • Role of loop inclination to vertical on thermalhydraulic stability is explored. • Inclination has strong stabilizing effect due to lower effective gravitation force. • Increase in tilt angle reduces settling time and highest amplitude of oscillation. • An angle of 15° is suggested for the selected loop geometry. - Abstract: Controlling stability behavior of single-phase natural circulation loops, without significantly affecting its steady-state characteristics, is a topic of wide research interest. Present study explores the role of loop inclination on a particular loop geometry. Accordingly a 3D computational model of a rectangular loop is developed and transient conservation equations are solved to obtain the temporal variation in flow parameters. Starting from the quiescent state, simulations are performed for selected sets of operating conditions and also with a few selected inclination angles. System experiences instability at higher heater powers and also with higher sink temperatures. Inclination is found to have a strong stabilizing influence owing to the reduction in the effective gravitational acceleration and subsequent decline in local buoyancy effects. The settling time and highest amplitude of oscillations substantially reduces for a stable system with a small inclination. Typically-unstable systems can also suppress the oscillations, when subjected to tilting, within a reasonable period of time. It is possible to stabilize the loop within shorter time span by increasing the tilt angle, but at the expense of reduction in steady-state flow rate. Overall a tilt angle of 15° is suggested for the selected geometry. Results from the 3D model is compared with the predictions from an indigenous 1D code. While similar qualitative influence of inclination is observed, the 1D model predicts early appearance of the stability threshold and hence hints

FamSeq: a variant calling program for family-based sequencing data using graphics processing units.

Directory of Open Access Journals (Sweden)

Gang Peng

2014-10-01

Full Text Available Various algorithms have been developed for variant calling using next-generation sequencing data, and various methods have been applied to reduce the associated false positive and false negative rates. Few variant calling programs, however, utilize the pedigree information when the family-based sequencing data are available. Here, we present a program, FamSeq, which reduces both false positive and false negative rates by incorporating the pedigree information from the Mendelian genetic model into variant calling. To accommodate variations in data complexity, FamSeq consists of four distinct implementations of the Mendelian genetic model: the Bayesian network algorithm, a graphics processing unit version of the Bayesian network algorithm, the Elston-Stewart algorithm and the Markov chain Monte Carlo algorithm. To make the software efficient and applicable to large families, we parallelized the Bayesian network algorithm that copes with pedigrees with inbreeding loops without losing calculation precision on an NVIDIA graphics processing unit. In order to compare the difference in the four methods, we applied FamSeq to pedigree sequencing data with family sizes that varied from 7 to 12. When there is no inbreeding loop in the pedigree, the Elston-Stewart algorithm gives analytical results in a short time. If there are inbreeding loops in the pedigree, we recommend the Bayesian network method, which provides exact answers. To improve the computing speed of the Bayesian network method, we parallelized the computation on a graphics processing unit. This allowed the Bayesian network method to process the whole genome sequencing data of a family of 12 individuals within two days, which was a 10-fold time reduction compared to the time required for this computation on a central processing unit.

Diffusion of Wilson loops

International Nuclear Information System (INIS)

Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

2005-01-01

A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

One-loop calculations in quantum field theory: from Feynman diagrams to unitarity cuts

Energy Technology Data Exchange (ETDEWEB)

Ellis, R. Keith [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Kunszt, Zoltan [Institute for Theoretical Physics (Switzerland); Melnikov, Kirill [Johns Hopkins Univ., Baltimore, MD (United States); Zanderighi, Giulia [Rudolf Peierls Centre for Theoretical Physics (United Kingdom)

2012-09-01

The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques become inefficient. Recently new approaches based on unitarity have been developed for calculating one-loop scattering amplitudes in quantum field theory. These methods are especially suitable for the description of multi-particle processes in QCD and are amenable to numerical implementations. We present a systematic pedagogical description of both conceptual and technical aspects of the new methods.

One-loop calculations in quantum field theory: From Feynman diagrams to unitarity cuts

International Nuclear Information System (INIS)

Ellis, R. Keith; Kunszt, Zoltan; Melnikov, Kirill; Zanderighi, Giulia

2012-01-01

The success of the experimental program at the Tevatron re-inforced the idea that precision physics at hadron colliders is desirable and, indeed, possible. The Tevatron data strongly suggests that one-loop computations in QCD describe hard scattering well. Extrapolating this observation to the LHC, we conclude that knowledge of many short-distance processes at next-to-leading order may be required to describe the physics of hard scattering. While the field of one-loop computations is quite mature, parton multiplicities in hard LHC events are so high that traditional computational techniques become inefficient. Recently, new approaches based on unitarity have been developed for calculating one-loop scattering amplitudes in quantum field theory. These methods are especially suitable for the description of multi-particle processes in QCD and are amenable to numerical implementations. We present a systematic pedagogical description of both conceptual and technical aspects of the new methods.

On some properties of conjugacy closed loops

International Nuclear Information System (INIS)

Adeniran, John Olusola

2002-07-01

It is shown that central loops are not conjugacy closed loops but instead are loops of units in their loop algebras that are conjugacy closed. It is also shown that certain inner mappings of a conjugacy closed loop are nuclear. Some invariants of left conjugacy closed loops are obtained. (author)

The interplay of multiple feedback loops with post-translational kinetics results in bistability of mycobacterial stress response

International Nuclear Information System (INIS)

Tiwari, Abhinav; Igoshin, Oleg A; Balázsi, Gábor; Gennaro, Maria Laura

2010-01-01

Bacterial persistence is the phenomenon in which a genetically identical fraction of a bacterial population can survive exposure to stress by reduction or cessation of growth. Persistence in mycobacteria has been recently linked to a stress-response network, consisting of the MprA/MprB two-component system and alternative sigma factor σ E . This network contains multiple positive transcriptional feedback loops which may give rise to bistability, making it a good candidate for controlling the mycobacterial persistence switch. To analyze the possibility of bistability, we develop a method that involves decoupling of the network into transcriptional and post-translational interaction modules. As a result we reduce the dimensionality of the dynamical system and independently analyze input–output relations in the two modules to formulate a necessary condition for bistability in terms of their logarithmic gains. We show that neither the positive autoregulation in the MprA/MprB network nor the σ E -mediated transcriptional feedback is sufficient to induce bistability in a biochemically realistic parameter range. Nonetheless, inclusion of the post-translational regulation of σ E by RseA increases the effective cooperativity of the system, resulting in bistability that is robust to parameter variation. We predict that overexpression or deletion of RseA, the key element controlling the ultrasensitive response, can eliminate bistability

A Three Level Framework for Closed-Loop Supply Chain Management—Linking Society, Chain and Actor Level

Directory of Open Access Journals (Sweden)

Stefan Seuring

2011-04-01

Full Text Available Supply chain management and closed-loop supply chain management (CLSCM have developed into established concepts in recent years. The related material cycles and product returns form an important part of all related processes with high potential for reducing environmental burden. The paper proposes a framework for (environmentally triggered closed-loop supply chain management, spanning three different levels: the societal or governance, the chain and the actor level. Within each level, a set of activities or processes can be identified. Taken together, the levels allow a comprehensive analysis of a closed-loop supply chain system. This is illustrated building on two case studies in the textile and apparel industry, where closed-loop supply chains have been designed to take specific apparel products back. The case studies are analyzed against all three levels and allow exemplification of related challenges and interrelations among the three levels. The three levels contribute to the further comprehension of the multiple issues having to be taken into account for successfully implementing closed-loop supply chains.

Mirror symmetry and loop operators

Energy Technology Data Exchange (ETDEWEB)

Assel, Benjamin [Department of Mathematics, King’s College London,The Strand, London WC2R 2LS (United Kingdom); Gomis, Jaume [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada)

2015-11-09

Wilson loops in gauge theories pose a fundamental challenge for dualities. Wilson loops are labeled by a representation of the gauge group and should map under duality to loop operators labeled by the same data, yet generically, dual theories have completely different gauge groups. In this paper we resolve this conundrum for three dimensional mirror symmetry. We show that Wilson loops are exchanged under mirror symmetry with Vortex loop operators, whose microscopic definition in terms of a supersymmetric quantum mechanics coupled to the theory encode in a non-trivial way a representation of the original gauge group, despite that the gauge groups of mirror theories can be radically different. Our predictions for the mirror map, which we derive guided by branes in string theory, are confirmed by the computation of the exact expectation value of Wilson and Vortex loop operators on the three-sphere.

Interlinked dual-time feedback loops can enhance robustness to stochasticity and persistence of memory.

Science.gov (United States)

Smolen, Paul; Baxter, Douglas A; Byrne, John H

2009-03-01

Multiple interlinked positive feedback loops shape the stimulus responses of various biochemical systems, such as the cell cycle or intracellular Ca2+ release. Recent studies with simplified models have identified two advantages of coupling fast and slow feedback loops. This dual-time structure enables a fast response while enhancing resistances of responses and bistability to stimulus noise. We now find that (1) the dual-time structure similarly confers resistance to internal noise due to molecule number fluctuations, and (2) model variants with altered coupling, which better represent some specific biochemical systems, share all the above advantages. We also develop a similar bistable model with coupling of a fast autoactivation loop to a slow loop. This model's topology was suggested by positive feedback proposed to play a role in long-term synaptic potentiation (LTP). The advantages of fast response and noise resistance are also present in this autoactivation model. Empirically, LTP develops resistance to reversal over approximately 1h . The model suggests this resistance may result from increased amounts of synaptic kinases involved in positive feedback.

Performance Analysis of a De-correlated Modified Code Tracking Loop for Synchronous DS-CDMA System under Multiuser Environment

Science.gov (United States)

Wu, Ya-Ting; Wong, Wai-Ki; Leung, Shu-Hung; Zhu, Yue-Sheng

This paper presents the performance analysis of a De-correlated Modified Code Tracking Loop (D-MCTL) for synchronous direct-sequence code-division multiple-access (DS-CDMA) systems under multiuser environment. Previous studies have shown that the imbalance of multiple access interference (MAI) in the time lead and time lag portions of the signal causes tracking bias or instability problem in the traditional correlating tracking loop like delay lock loop (DLL) or modified code tracking loop (MCTL). In this paper, we exploit the de-correlating technique to combat the MAI at the on-time code position of the MCTL. Unlike applying the same technique to DLL which requires an extensive search algorithm to compensate the noise imbalance which may introduce small tracking bias under low signal-to-noise ratio (SNR), the proposed D-MCTL has much lower computational complexity and exhibits zero tracking bias for the whole range of SNR, regardless of the number of interfering users. Furthermore, performance analysis and simulations based on Gold codes show that the proposed scheme has better mean square tracking error, mean-time-to-lose-lock and near-far resistance than the other tracking schemes, including traditional DLL (T-DLL), traditional MCTL (T-MCTL) and modified de-correlated DLL (MD-DLL).

WWER type reactor primary loop imitation on large test loop facility in MARIA reactor

International Nuclear Information System (INIS)

Moldysh, A.; Strupchevski, A.; Kmetek, Eh.; Spasskov, V.P.; Shumskij, A.M.

1982-01-01

At present in Poland in cooperation with USSR a nuclear water loop test facility (WL) in 'MARIA' reactor in Sverke is under construction. The program objective is to investigate processes occuring in WWER reactor under emergency conditions, first of all after the break of the mainprimary loop circulation pipe-line. WL with the power of about 600 kW consists of three major parts: 1) an active loop, imitating the undamaged loops of the WWER reactor; 2) a passive loop assignedfor modelling the broken loop of the WWER reactor; 3) the emergency core cooling system imitating the corresponding full-scale system. The fuel rod bundle consists of 18 1 m long rods. They were fabricated according to the standard WWER fuel technology. In the report some general principles of WWERbehaviour imitation under emergency conditions are given. They are based on the operation experience obtained from 'SEMISCALE' and 'LOFT' test facilities in the USA. A description of separate modelling factors and criteria effects on the development of 'LOCA'-type accident is presented (the break cross-section to the primary loop volume ratio, the pressure differential between inlet and outlet reactor chambers, the pressure drop rate in the loop, the coolant flow rate throuh the core etc.). As an example a comparison of calculated flow rate variations for the WWER-1000 reactor and the model during the loss-of-coolant accident with the main pipe-line break at the core inlet is given. Calculations have been carried out with the use of TECH'-M code [ru

Natively unstructured loops differ from other loops.

Directory of Open Access Journals (Sweden)

Avner Schlessinger

2007-07-01

Full Text Available Natively unstructured or disordered protein regions may increase the functional complexity of an organism; they are particularly abundant in eukaryotes and often evade structure determination. Many computational methods predict unstructured regions by training on outliers in otherwise well-ordered structures. Here, we introduce an approach that uses a neural network in a very different and novel way. We hypothesize that very long contiguous segments with nonregular secondary structure (NORS regions differ significantly from regular, well-structured loops, and that a method detecting such features could predict natively unstructured regions. Training our new method, NORSnet, on predicted information rather than on experimental data yielded three major advantages: it removed the overlap between testing and training, it systematically covered entire proteomes, and it explicitly focused on one particular aspect of unstructured regions with a simple structural interpretation, namely that they are loops. Our hypothesis was correct: well-structured and unstructured loops differ so substantially that NORSnet succeeded in their distinction. Benchmarks on previously used and new experimental data of unstructured regions revealed that NORSnet performed very well. Although it was not the best single prediction method, NORSnet was sufficiently accurate to flag unstructured regions in proteins that were previously not annotated. In one application, NORSnet revealed previously undetected unstructured regions in putative targets for structural genomics and may thereby contribute to increasing structural coverage of large eukaryotic families. NORSnet found unstructured regions more often in domain boundaries than expected at random. In another application, we estimated that 50%-70% of all worm proteins observed to have more than seven protein-protein interaction partners have unstructured regions. The comparative analysis between NORSnet and DISOPRED2 suggested

Loop corrections and a new test of inflation

CERN Document Server

Tasinato, Gianmassimo; Nurmi, Sami; Wands, David

2013-01-01

Inflation is the leading paradigm for explaining the origin of primordial density perturbations and the observed temperature fluctuations of the cosmic microwave background. However many open questions remain, in particular whether one or more scalar fields were present during inflation and how they contributed to the primordial density perturbation. We propose a new observational test of whether multiple fields, or only one (not necessarily the inflaton) generated the perturbations. We show that our test, relating the bispectrum and trispectrum, is protected against loop corrections at all orders, unlike previous relations.

A type of loop algebra and the associated loop algebras

International Nuclear Information System (INIS)

Tam Honwah; Zhang Yufeng

2008-01-01

A higher-dimensional twisted loop algebra is constructed. As its application, a new Lax pair is presented, whose compatibility gives rise to a Liouville integrable hierarchy of evolution equations by making use of Tu scheme. One of the reduction cases of the hierarchy is an analogous of the well-known AKNS system. Next, the twisted loop algebra, furthermore, is extended to another higher dimensional loop algebra, from which a hierarchy of evolution equations with 11-potential component functions is obtained, whose reduction is just standard AKNS system. Especially, we prove that an arbitrary linear combination of the four Hamiltonian operators directly obtained from the recurrence relations is still a Hamiltonian operator. Therefore, the hierarchy with 11-potential functions possesses 4-Hamiltonian structures. Finally, an integrable coupling of the hierarchy is worked out

DETERMINING HEATING RATES IN RECONNECTION FORMED FLARE LOOPS OF THE M8.0 FLARE ON 2005 MAY 13

Energy Technology Data Exchange (ETDEWEB)

Liu Wenjuan; Qiu Jiong; Longcope, Dana W. [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Caspi, Amir [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States)

2013-06-20

We analyze and model an M8.0 flare on 2005 May 13 observed by the Transition Region and Coronal Explorer and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to determine the energy release rate from magnetic reconnection that forms and heats numerous flare loops. The flare exhibits two ribbons in UV 1600 A emission. Analysis shows that the UV light curve at each flaring pixel rises impulsively within a few minutes, and decays slowly with a timescale longer than 10 minutes. Since the lower atmosphere (the transition region and chromosphere) responds to energy deposit nearly instantaneously, the rapid UV brightening is thought to reflect the energy release process in the newly formed flare loop rooted at the footpoint. In this paper, we utilize the spatially resolved (down to 1'') UV light curves and the thick-target hard X-ray emission to construct heating functions of a few thousand flare loops anchored at the UV footpoints, and compute plasma evolution in these loops using the enthalpy-based thermal evolution of loops model. The modeled coronal temperatures and densities of these flare loops are then used to calculate coronal radiation. The computed soft X-ray spectra and light curves compare favorably with those observed by RHESSI and by the Geostationary Operational Environmental Satellite X-ray Sensor. The time-dependent transition region differential emission measure for each loop during its decay phase is also computed with a simplified model and used to calculate the optically thin C IV line emission, which dominates the UV 1600 A bandpass during the flare. The computed C IV line emission decays at the same rate as observed. This study presents a method to constrain heating of reconnection-formed flare loops using all available observables independently, and provides insight into the physics of energy release and plasma heating during the flare. With this method, the lower limit of the total energy used to heat the flare loops in

Four loop wave function renormalization in the non-abelian Thirring model

International Nuclear Information System (INIS)

Ali, D.B.; Gracey, J.A.

2001-01-01

We compute the anomalous dimension of the fermion field with N f flavours in the fundamental representation of a general Lie colour group in the non-abelian Thirring model at four loops. The implications on the renormalization of the two point Green's function through the loss of multiplicative renormalizability of the model in dimensional regularization due to the appearance of evanescent four fermi operators are considered at length. We observe the appearance of one new colour group Casimir, d F abcd d F abcd , in the final four loop result and discuss its consequences for the relation of the Knizhnik-Zamolodchikov critical exponents in the Wess-Zumino-Witten-Novikov model to the non-abelian Thirring model. Renormalization scheme changes are also considered to ensure that the underlying Fierz symmetry broken by dimensional regularization is restored

Modeling of compact loop antennas

International Nuclear Information System (INIS)

Baity, F.W.

1987-01-01

A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively-tuned resonant double loop (RDL) antennas the model treats stub-tuned resonant double loop antennas. Calculations using the model have been compared with measurements on full-scale mockups of resonant double loop antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and for the Compact Ignition Tokamak

Rogowski Loop design for NSTX

International Nuclear Information System (INIS)

McCormack, B.; Kaita, R.; Kugel, H.; Hatcher, R.

2000-01-01

The Rogowski Loop is one of the most basic diagnostics for tokamak operations. On the National Spherical Torus Experiment (NSTX), the plasma current Rogowski Loop had the constraints of the very limited space available on the center stack, 5,000 volt isolation, flexibility requirements as it remained a part of the Center Stack assembly after the first phase of operation, and a +120 C temperature requirement. For the second phase of operation, four Halo Current Rogowski Loops under the Center Stack tiles will be installed having +600 C and limited space requirements. Also as part of the second operational phase, up to ten Rogowski Loops will installed to measure eddy currents in the Passive Plate support structures with +350 C, restricted space, and flexibility requirements. This presentation will provide the details of the material selection, fabrication techniques, testing, and installation results of the Rogowski Loops that were fabricated for the high temperature operational and bakeout requirements, high voltage isolation requirements, and the space and flexibility requirements imposed upon the Rogowski Loops. In the future operational phases of NSTX, additional Rogowski Loops could be anticipated that will measure toroidal plasma currents in the vacuum vessel and in the Passive Plate assemblies

H-infty Control of systems with multiple i/o delays

NARCIS (Netherlands)

Agoes Ariffin Moelja, A.A.; Meinsma, Gjerrit; Mirkin, Leonid

2003-01-01

In this paper the standard (four-block) H-infty control problem for systems with multiple i/o delays in the feedback loop is studied. The central idea is to see the multiple delay operator as a special series connection of elementary delay operators, called the adobe delay operators. The adobe delay

Hybrid Combustion-Gasification Chemical Looping

Energy Technology Data Exchange (ETDEWEB)

Herbert Andrus; Gregory Burns; John Chiu; Gregory Lijedahl; Peter Stromberg; Paul Thibeault

2009-01-07

For the past several years Alstom Power Inc. (Alstom), a leading world-wide power system manufacturer and supplier, has been in the initial stages of developing an entirely new, ultra-clean, low cost, high efficiency power plant for the global power market. This new power plant concept is based on a hybrid combustion-gasification process utilizing high temperature chemical and thermal looping technology The process consists of the oxidation, reduction, carbonation, and calcination of calcium-based compounds, which chemically react with coal, biomass, or opportunity fuels in two chemical loops and one thermal loop. The chemical and thermal looping technology can be alternatively configured as (i) a combustion-based steam power plant with CO{sub 2} capture, (ii) a hybrid combustion-gasification process producing a syngas for gas turbines or fuel cells, or (iii) an integrated hybrid combustion-gasification process producing hydrogen for gas turbines, fuel cells or other hydrogen based applications while also producing a separate stream of CO{sub 2} for use or sequestration. In its most advanced configuration, this new concept offers the promise to become the technology link from today's Rankine cycle steam power plants to tomorrow's advanced energy plants. The objective of this work is to develop and verify the high temperature chemical and thermal looping process concept at a small-scale pilot facility in order to enable AL to design, construct and demonstrate a pre-commercial, prototype version of this advanced system. In support of this objective, Alstom and DOE started a multi-year program, under this contract. Before the contract started, in a preliminary phase (Phase 0) Alstom funded and built the required small-scale pilot facility (Process Development Unit, PDU) at its Power Plant Laboratories in Windsor, Connecticut. Construction was completed in calendar year 2003. The objective for Phase I was to develop the indirect combustion loop with CO{sub 2

Thermal-hydraulic analyses for in-pile SCWR fuel qualification test loops and SCWR material loop

Energy Technology Data Exchange (ETDEWEB)

Vojacek, A.; Mazzini, G.; Zmitkova, J.; Ruzickova, M. [Research Centre Rez (Czech Republic)

2014-07-01

One of the R&D directions of Research Centre Rez is dedicated to the supercritical water-cooled reactor concept (SCWR). Among the developed experimental facilities and infrastructure in the framework of the SUSEN project (SUStainable ENergy) is construction and experimental operation of the supercritical water loop SCWL focusing on material tests. At the first phase, this SCWL loop is assembled and operated out-of-pile in the dedicated loop facilities hall. At this out-of-pile operation various operational conditions are tested and verified. After that, in the second phase, the SCWL loop will be situated in-pile, in the core of the research reactor LVR-15, operated at CVR. Furthermore, it is planned to carry out a test of a small scale fuel assembly within the SuperCritical Water Reactor Fuel Qualification Test (SCWR-FQT) loop, which is now being designed. This paper presents the results of the thermal-hydraulic analyses of SCWL loop out-of-pile operation using the RELAP5/MOD3.3. The thermal-hydraulic modeling and the performed analyses are focused on the SCWL loop model validation through a comparison of the calculation results with the experimental results obtained at various operation conditions. Further, the present paper focuses on the transient analyses for start-up and shut-down of the FQT loop, particularly to explore the ability of system codes ATHLET 3.0A to simulate the transient between subcritical conditions and supercritical conditions. (author)

Algorithm for counting large directed loops

Energy Technology Data Exchange (ETDEWEB)

Bianconi, Ginestra [Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste (Italy); Gulbahce, Natali [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, NM 87545 (United States)

2008-06-06

We derive a Belief-Propagation algorithm for counting large loops in a directed network. We evaluate the distribution of the number of small loops in a directed random network with given degree sequence. We apply the algorithm to a few characteristic directed networks of various network sizes and loop structures and compare the algorithm with exhaustive counting results when possible. The algorithm is adequate in estimating loop counts for large directed networks and can be used to compare the loop structure of directed networks and their randomized counterparts.

Oscillation damping of chiral string loops

International Nuclear Information System (INIS)

Babichev, Eugeny; Dokuchaev, Vyacheslav

2002-01-01

Chiral cosmic string loops tend to the stationary (vorton) configuration due to energy loss into gravitational and electromagnetic radiation. We describe the asymptotic behavior of near stationary chiral loops and their fading to vortons. General limits on the gravitational and electromagnetic energy losses by near stationary chiral loops are found. For these loops we estimate the oscillation damping time. We present solvable examples of gravitational radiation energy loss by some chiral loop configurations. The analytical dependence of string energy with time is found in the case of the chiral ring with small amplitude radial oscillations

LoopX: A Graphical User Interface-Based Database for Comprehensive Analysis and Comparative Evaluation of Loops from Protein Structures.

Science.gov (United States)

Kadumuri, Rajashekar Varma; Vadrevu, Ramakrishna

2017-10-01

Due to their crucial role in function, folding, and stability, protein loops are being targeted for grafting/designing to create novel or alter existing functionality and improve stability and foldability. With a view to facilitate a thorough analysis and effectual search options for extracting and comparing loops for sequence and structural compatibility, we developed, LoopX a comprehensively compiled library of sequence and conformational features of ∼700,000 loops from protein structures. The database equipped with a graphical user interface is empowered with diverse query tools and search algorithms, with various rendering options to visualize the sequence- and structural-level information along with hydrogen bonding patterns, backbone φ, ψ dihedral angles of both the target and candidate loops. Two new features (i) conservation of the polar/nonpolar environment and (ii) conservation of sequence and conformation of specific residues within the loops have also been incorporated in the search and retrieval of compatible loops for a chosen target loop. Thus, the LoopX server not only serves as a database and visualization tool for sequence and structural analysis of protein loops but also aids in extracting and comparing candidate loops for a given target loop based on user-defined search options.

Closed-loop surface-related multiple elimination and its application to simultaneous data reconstruction

NARCIS (Netherlands)

Lopez Angarita, G.A.; Verschuur, D.J.

2015-01-01

Surface-related multiple elimination (SRME) is one of the most commonly used methods for suppressing surface multiples. However, to obtain an accurate surface multiple estimation, dense source and receiver sampling is required. The traditional approach to this problem is performing data

Fully Closed-Loop Multiple Model Probabilistic Predictive Controller Artificial Pancreas Performance in Adolescents and Adults in a Supervised Hotel Setting.

Science.gov (United States)

Forlenza, Gregory P; Cameron, Faye M; Ly, Trang T; Lam, David; Howsmon, Daniel P; Baysal, Nihat; Kulina, Georgia; Messer, Laurel; Clinton, Paula; Levister, Camilla; Patek, Stephen D; Levy, Carol J; Wadwa, R Paul; Maahs, David M; Bequette, B Wayne; Buckingham, Bruce A

2018-05-01

Initial Food and Drug Administration-approved artificial pancreas (AP) systems will be hybrid closed-loop systems that require prandial meal announcements and will not eliminate the burden of premeal insulin dosing. Multiple model probabilistic predictive control (MMPPC) is a fully closed-loop system that uses probabilistic estimation of meals to allow for automated meal detection. In this study, we describe the safety and performance of the MMPPC system with announced and unannounced meals in a supervised hotel setting. The Android phone-based AP system with remote monitoring was tested for 72 h in six adults and four adolescents across three clinical sites with daily exercise and meal challenges involving both three announced (manual bolus by patient) and six unannounced (no bolus by patient) meals. Safety criteria were predefined. Controller aggressiveness was adapted daily based on prior hypoglycemic events. Mean 24-h continuous glucose monitor (CGM) was 157.4 ± 14.4 mg/dL, with 63.6 ± 9.2% of readings between 70 and 180 mg/dL, 2.9 ± 2.3% of readings 250 mg/dL. Moderate hyperglycemia was relatively common with 24.6 ± 6.2% of readings between 180 and 250 mg/dL, primarily within 3 h after a meal. Overnight mean CGM was 139.6 ± 27.6 mg/dL, with 77.9 ± 16.4% between 70 and 180 mg/dL, 3.0 ± 4.5% 250 mg/dL. Postprandial hyperglycemia was more common for unannounced meals compared with announced meals (4-h postmeal CGM 197.8 ± 44.1 vs. 140.6 ± 35.0 mg/dL; P < 0.001). No participants met safety stopping criteria. MMPPC was safe in a supervised setting despite meal and exercise challenges. Further studies are needed in a less supervised environment.

On the loop-loop scattering amplitudes in Abelian and non-Abelian gauge theories

International Nuclear Information System (INIS)

Meggiolaro, Enrico

2005-01-01

The high-energy elastic scattering amplitude of two colour-singlet qq-bar pairs is governed by the correlation function of two Wilson loops, which follow the classical straight lines for quark (antiquark) trajectories. This quantity is expected to be free of IR divergences, differently from what happens for the parton-parton elastic scattering amplitude, described, in the high-energy limit, by the expectation value of two Wilson lines. We shall explicitly test this IR finiteness by a direct non-perturbative computation of the loop-loop scattering amplitudes in the (pedagogic, but surely physically interesting) case of quenched QED. The results obtained for the Abelian case will be generalized to the case of a non-Abelian gauge theory with Nc colours, but stopping to the order O(g4) in perturbation theory. In connection with the above-mentioned IR finiteness, we shall also discuss some analytic properties of the loop-loop scattering amplitudes in both Abelian and non-Abelian gauge theories, when going from Minkowskian to Euclidean theory, which can be relevant to the still unsolved problem of the s-dependence of hadron-hadron total cross-sections

New Hamiltonians for loop quantum cosmology with arbitrary spin representations

Science.gov (United States)

Ben Achour, Jibril; Brahma, Suddhasattwa; Geiller, Marc

2017-04-01

In loop quantum cosmology, one has to make a choice of SU(2) irreducible representation in which to compute holonomies and regularize the curvature of the connection. The systematic choice made in the literature is to work in the fundamental representation, and very little is known about the physics associated with higher spin labels. This constitutes an ambiguity of which the understanding, we believe, is fundamental for connecting loop quantum cosmology to full theories of quantum gravity like loop quantum gravity, its spin foam formulation, or cosmological group field theory. We take a step in this direction by providing here a new closed formula for the Hamiltonian of flat Friedmann-Lemaître-Robertson-Walker models regularized in a representation of arbitrary spin. This expression is furthermore polynomial in the basic variables which correspond to well-defined operators in the quantum theory, takes into account the so-called inverse-volume corrections, and treats in a unified way two different regularization schemes for the curvature. After studying the effective classical dynamics corresponding to single and multiple-spin Hamiltonians, we study the behavior of the critical density when the number of representations is increased and the stability of the difference equations in the quantum theory.

Higher dimensional loop quantum cosmology

International Nuclear Information System (INIS)

Zhang, Xiangdong

2016-01-01

Loop quantum cosmology (LQC) is the symmetric sector of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogeneous cosmological model in n + 1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n + 1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n + 1 dimensional model and the 3 + 1 dimensional one. Our model serves as a first example of higher dimensional loop quantum cosmology and offers the possibility to investigate quantum gravity effects in higher dimensional cosmology. (orig.)

Hyperstaticity and loops in frictional granular packings

Science.gov (United States)

Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

2009-06-01

The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

Loop Heat Pipe Startup Behaviors

Science.gov (United States)

Ku, Jentung

2016-01-01

A loop heat pipe must start successfully before it can commence its service. The startup transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe startup behaviors. Topics include the four startup scenarios, the initial fluid distribution between the evaporator and reservoir that determines the startup scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power startup, and methods to enhance the startup success. Also addressed are the pressure spike and pressure surge during the startup transient, and repeated cycles of loop startup and shutdown under certain conditions.

Conformal boundary loop models

International Nuclear Information System (INIS)

Jacobsen, Jesper Lykke; Saleur, Hubert

2008-01-01

We study a model of densely packed self-avoiding loops on the annulus, related to the Temperley-Lieb algebra with an extra idempotent boundary generator. Four different weights are given to the loops, depending on their homotopy class and whether they touch the outer rim of the annulus. When the weight of a contractible bulk loop x≡q+q -1 element of (-2,2], this model is conformally invariant for any real weight of the remaining three parameters. We classify the conformal boundary conditions and give exact expressions for the corresponding boundary scaling dimensions. The amplitudes with which the sectors with any prescribed number and types of non-contractible loops appear in the full partition function Z are computed rigorously. Based on this, we write a number of identities involving Z which hold true for any finite size. When the weight of a contractible boundary loop y takes certain discrete values, y r ≡([r+1] q )/([r] q ) with r integer, other identities involving the standard characters K r,s of the Virasoro algebra are established. The connection with Dirichlet and Neumann boundary conditions in the O(n) model is discussed in detail, and new scaling dimensions are derived. When q is a root of unity and y=y r , exact connections with the A m type RSOS model are made. These involve precise relations between the spectra of the loop and RSOS model transfer matrices, valid in finite size. Finally, the results where y=y r are related to the theory of Temperley-Lieb cabling

The complete two-loop integrated jet thrust distribution in soft-collinear effective theory

International Nuclear Information System (INIS)

Manteuffel, Andreas von; Schabinger, Robert M.; Zhu, Hua Xing

2014-01-01

In this work, we complete the calculation of the soft part of the two-loop integrated jet thrust distribution in e + e − annihilation. This jet mass observable is based on the thrust cone jet algorithm, which involves a veto scale for out-of-jet radiation. The previously uncomputed part of our result depends in a complicated way on the jet cone size, r, and at intermediate stages of the calculation we actually encounter a new class of multiple polylogarithms. We employ an extension of the coproduct calculus to systematically exploit functional relations and represent our results concisely. In contrast to the individual contributions, the sum of all global terms can be expressed in terms of classical polylogarithms. Our explicit two-loop calculation enables us to clarify the small r picture discussed in earlier work. In particular, we show that the resummation of the logarithms of r that appear in the previously uncomputed part of the two-loop integrated jet thrust distribution is inextricably linked to the resummation of the non-global logarithms. Furthermore, we find that the logarithms of r which cannot be absorbed into the non-global logarithms in the way advocated in earlier work have coefficients fixed by the two-loop cusp anomalous dimension. We also show that in many cases one can straightforwardly predict potentially large logarithmic contributions to the integrated jet thrust distribution at L loops by making use of analogous contributions to the simpler integrated hemisphere soft function

Mitochondrial D-loop sequence of domesticated waterfowl in Central Java: goose and muscovy duck

Science.gov (United States)

Susanti, R.; Iswari, R. S.

2018-03-01

This study aims to determine the genetic characterization of domesticated waterfowl (goose and Muscovy duck) in Central Java based on a D-loop mtDNA gene. The D-loop gene was amplified using PCR technique by specific primer and sequenced using dideoxy termination method. Multiple alignments of D-loop gene obtained were 710 nucleotides at position 74 to 783 at the 5’ end (for goose) and 712 nucleotides at position 48 to 759 at the 5’ end (for Muscovy duck). The results of the polymorphism analysis on D-loop sequences of muscovy duck produced 3 haplotypes. In the D-loop gene of goose does not show polymorphism, with substitution at G117A. Phylogenetic trees reconstructions of goose and Muscovy duck, which was collected during this research compared with another species from Anser, Chairina and Anas was generated 2 forms of clusters. The first group consists of all kind of Muscovy duck together with Chairina moschata and Anas, while the second group consists of all geese and Anser cygnoides the other. The determination of Muscovy duck and geese identity can be distinguished from the genetic marker information. Based on the phylogenetic analysis, it can be concluded that the Muscovy duck is closely related to Chairina moschata, while geese is closely related to Anser cygnoides.

Large lithium loop experience

International Nuclear Information System (INIS)

Kolowith, R.; Owen, T.J.; Berg, J.D.; Atwood, J.M.

1981-10-01

An engineering design and operating experience of a large, isothermal, lithium-coolant test loop are presented. This liquid metal coolant loop is called the Experimental Lithium System (ELS) and has operated safely and reliably for over 6500 hours through September 1981. The loop is used for full-scale testing of components for the Fusion Materials Irradiation Test (FMIT) Facility. Main system parameters include coolant temperatures to 430 0 C and flow to 0.038 m 3 /s (600 gal/min). Performance of the main pump, vacuum system, and control system is discussed. Unique test capabilities of the ELS are also discussed

Modular invariance and covariant loop calculus

International Nuclear Information System (INIS)

Petersen, J.L.; Roland, K.O.; Sidenius, J.R.

1988-01-01

The covariant loop calculus provides an efficient technique for computing explicit expressions for the density on moduli space corresponding to arbitrary (bosonic string) loop diagrams. Since modular invariance is not manifest, however, we carry out a detailed comparison with known explicit two- and three-loop results derived using analytic geometry (one loop is known to be okay). We establish identity to 'high' order in some moduli and exactly in others. Agreement is found as a result of various nontrivial cancellations, in part related to number theory. We feel our results provide very strong support for the correctness of the covariant loop calculus approach. (orig.)

Modular invariance and covariant loop calculus

International Nuclear Information System (INIS)

Petersen, J.L.; Roland, K.O.; Sidenius, J.R.

1988-01-01

The covariant loop calculus provides and efficient technique for computing explicit expressions for the density on moduli space corresponding to arbitrary (bosonic string) loop diagrams. Since modular invariance is not manifest, however, we carry out a detailed comparison with known explicit 2- and 3- loop results derived using analytic geometry (1 loop is known to be ok). We establish identity to 'high' order in some moduli and exactly in others. Agreement is found as a result of various non-trivial cancellations, in part related to number theory. We feel our results provide very strong support for the correctness of the covariant loop calculus approach. (orig.)

Parallel tiled Nussinov RNA folding loop nest generated using both dependence graph transitive closure and loop skewing.

Science.gov (United States)

Palkowski, Marek; Bielecki, Wlodzimierz

2017-06-02

RNA secondary structure prediction is a compute intensive task that lies at the core of several search algorithms in bioinformatics. Fortunately, the RNA folding approaches, such as the Nussinov base pair maximization, involve mathematical operations over affine control loops whose iteration space can be represented by the polyhedral model. Polyhedral compilation techniques have proven to be a powerful tool for optimization of dense array codes. However, classical affine loop nest transformations used with these techniques do not optimize effectively codes of dynamic programming of RNA structure predictions. The purpose of this paper is to present a novel approach allowing for generation of a parallel tiled Nussinov RNA loop nest exposing significantly higher performance than that of known related code. This effect is achieved due to improving code locality and calculation parallelization. In order to improve code locality, we apply our previously published technique of automatic loop nest tiling to all the three loops of the Nussinov loop nest. This approach first forms original rectangular 3D tiles and then corrects them to establish their validity by means of applying the transitive closure of a dependence graph. To produce parallel code, we apply the loop skewing technique to a tiled Nussinov loop nest. The technique is implemented as a part of the publicly available polyhedral source-to-source TRACO compiler. Generated code was run on modern Intel multi-core processors and coprocessors. We present the speed-up factor of generated Nussinov RNA parallel code and demonstrate that it is considerably faster than related codes in which only the two outer loops of the Nussinov loop nest are tiled.

Gauge theory loop operators and Liouville theory

International Nuclear Information System (INIS)

Drukker, Nadav; Teschner, Joerg

2009-10-01

We propose a correspondence between loop operators in a family of four dimensional N=2 gauge theories on S 4 - including Wilson, 't Hooft and dyonic operators - and Liouville theory loop operators on a Riemann surface. This extends the beautiful relation between the partition function of these N=2 gauge theories and Liouville correlators found by Alday, Gaiotto and Tachikawa. We show that the computation of these Liouville correlators with the insertion of a Liouville loop operator reproduces Pestun's formula capturing the expectation value of a Wilson loop operator in the corresponding gauge theory. We prove that our definition of Liouville loop operators is invariant under modular transformations, which given our correspondence, implies the conjectured action of S-duality on the gauge theory loop operators. Our computations in Liouville theory make an explicit prediction for the exact expectation value of 't Hooft and dyonic loop operators in these N=2 gauge theories. The Liouville loop operators are also found to admit a simple geometric interpretation within quantum Teichmueller theory as the quantum operators representing the length of geodesics. We study the algebra of Liouville loop operators and show that it gives evidence for our proposal as well as providing definite predictions for the operator product expansion of loop operators in gauge theory. (orig.)

A True Open-Loop Synchronization Technique

DEFF Research Database (Denmark)

Golestan, Saeed; Vidal, Ana; Yepes, Alejandro G.

2016-01-01

Synchronization techniques can be broadly classified into two major categories: Closed-loop and open-loop methods. The open-loop synchronization (OLS) techniques, contrary to the closed-loop ones, are unconditionally stable and benefit from a fast dynamic response. Their performance, however, tends...... is to develop a true OLS (and therefore, unconditionally stable) technique without any need for the calculation of sine and cosine functions. The effectiveness of the proposed synchronization technique is confirmed through the simulation and experimental results....

A kinematic view of loop closure.

Science.gov (United States)

Coutsias, Evangelos A; Seok, Chaok; Jacobson, Matthew P; Dill, Ken A

2004-03-01

We consider the problem of loop closure, i.e., of finding the ensemble of possible backbone structures of a chain segment of a protein molecule that is geometrically consistent with preceding and following parts of the chain whose structures are given. We reduce this problem of determining the loop conformations of six torsions to finding the real roots of a 16th degree polynomial in one variable, based on the robotics literature on the kinematics of the equivalent rotator linkage in the most general case of oblique rotators. We provide a simple intuitive view and derivation of the polynomial for the case in which each of the three pair of torsional axes has a common point. Our method generalizes previous work on analytical loop closure in that the torsion angles need not be consecutive, and any rigid intervening segments are allowed between the free torsions. Our approach also allows for a small degree of flexibility in the bond angles and the peptide torsion angles; this substantially enlarges the space of solvable configurations as is demonstrated by an application of the method to the modeling of cyclic pentapeptides. We give further applications to two important problems. First, we show that this analytical loop closure algorithm can be efficiently combined with an existing loop-construction algorithm to sample loops longer than three residues. Second, we show that Monte Carlo minimization is made severalfold more efficient by employing the local moves generated by the loop closure algorithm, when applied to the global minimization of an eight-residue loop. Our loop closure algorithm is freely available at http://dillgroup. ucsf.edu/loop_closure/. Copyright 2004 Wiley Periodicals, Inc. J Comput Chem 25: 510-528, 2004

Keeping Energy Savings in the LOOP

Energy Technology Data Exchange (ETDEWEB)

Parrish, Kristen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Mercado, Andrea [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2012-11-01

Mesa Lane Partners (MLP) partnered with the U.S. Department of Energy (DOE) to develop and implement solutions to a build a new, low-energy mixed-use building that consumes at least 50% less energy than requirements set by Energy Standard 90.1-2007 of the American Society of Heating, Refrigerating, and Air-conditioning Engineers (ASHRAE), the American National Standards Institute (ANSI), and the Illuminating Engineering Society of America (IESNA), as part of DOE’s Commercial Building Partnerships (CBP)3 Program. Lawrence Berkeley National Laboratory (LBNL) provided technical expertise in support of this DOE program. The privately developed 46,000-square-foot LOOP project, which is intended to provide affordable off-campus student housing in an underserved community next to University of California at Santa Barbara, will contain more than 7,000 square feet of retail space, a roof deck, an event space, a gym, and 48 apartments. The project developer, MLP, is aiming to exceed CBP requirement, targeting energy consumption that is at least 65% less than that required by the standard. If the LOOP meets this goal, it is expected to achieve Leadership in Energy and Environmental Design (LEED) Gold certification. To meet this goal, the project design incorporates a variety of energy efficiency measures (EEMs) that address the needs of the multiple use types that the project will house.

The Wilson loop and some applications

International Nuclear Information System (INIS)

Bezerra, V.B.

1983-01-01

A simple relation between the classical Wilson loop and the angular deviation in the parallel shift is found. An example of potential which given field copies and which give the same classical Wilson loop for a given trajectory is exchibited. Afterwards, the asymptotic behaviour of the Wilson loop for the BPST instanton and meron is discussed. Using the dimensional regularization technique to calculate the second order term of Quantum Wilson loop, the influence of geometrical factors for the residue in the polo due to contact points, cusp and intersections, in function of the upsilon dimension of the space-time is investigated. Finally, the charge renormalization in Quantum Electrodynamics using Quantum Wilson loop is calculated. (L.C.) [pt

The Wilson loop and some applications

International Nuclear Information System (INIS)

Bezerra, V.B.

1983-04-01

A simple relation between the classical Wilson loop and the angular deviation in the parallel displacement is found. An example of potentials which give field copies and which suplly the same classical Wilson loop for a particular trajectory is exhibited. The asymptotic behaviour of the Wilson loop for the BPST instanton and the meron, is discussed. By using the dimensional regularization technique to calculate the second order term of the quantum Wilson loop, the influence of geometrical factors for the residue in the pole due to contact points, cuspides and intersections, in function of the space-time ν, is investigated. Charge renormalization in Quantum electrodynamics is finally calculated by using the quantum Wilson loop. (L.C.) [pt

Collective estimation of multiple bivariate density functions with application to angular-sampling-based protein loop modeling

KAUST Repository

Maadooliat, Mehdi

2015-10-21

This paper develops a method for simultaneous estimation of density functions for a collection of populations of protein backbone angle pairs using a data-driven, shared basis that is constructed by bivariate spline functions defined on a triangulation of the bivariate domain. The circular nature of angular data is taken into account by imposing appropriate smoothness constraints across boundaries of the triangles. Maximum penalized likelihood is used to fit the model and an alternating blockwise Newton-type algorithm is developed for computation. A simulation study shows that the collective estimation approach is statistically more efficient than estimating the densities individually. The proposed method was used to estimate neighbor-dependent distributions of protein backbone dihedral angles (i.e., Ramachandran distributions). The estimated distributions were applied to protein loop modeling, one of the most challenging open problems in protein structure prediction, by feeding them into an angular-sampling-based loop structure prediction framework. Our estimated distributions compared favorably to the Ramachandran distributions estimated by fitting a hierarchical Dirichlet process model; and in particular, our distributions showed significant improvements on the hard cases where existing methods do not work well.

Collective estimation of multiple bivariate density functions with application to angular-sampling-based protein loop modeling

KAUST Repository

Maadooliat, Mehdi; Zhou, Lan; Najibi, Seyed Morteza; Gao, Xin; Huang, Jianhua Z.

2015-01-01

This paper develops a method for simultaneous estimation of density functions for a collection of populations of protein backbone angle pairs using a data-driven, shared basis that is constructed by bivariate spline functions defined on a triangulation of the bivariate domain. The circular nature of angular data is taken into account by imposing appropriate smoothness constraints across boundaries of the triangles. Maximum penalized likelihood is used to fit the model and an alternating blockwise Newton-type algorithm is developed for computation. A simulation study shows that the collective estimation approach is statistically more efficient than estimating the densities individually. The proposed method was used to estimate neighbor-dependent distributions of protein backbone dihedral angles (i.e., Ramachandran distributions). The estimated distributions were applied to protein loop modeling, one of the most challenging open problems in protein structure prediction, by feeding them into an angular-sampling-based loop structure prediction framework. Our estimated distributions compared favorably to the Ramachandran distributions estimated by fitting a hierarchical Dirichlet process model; and in particular, our distributions showed significant improvements on the hard cases where existing methods do not work well.

An experimental study of dislocation loop nucleation

International Nuclear Information System (INIS)

Bounaud, J.Y.; Leteurtre, J.

1975-01-01

The nucleation of dislocation loops is experimentally studied by observing the demixion of the Burgers vectors of dislocation loops nucleated in copper whiskers irradiated in flexion by fission fragments at room temperature. The demixion of Burgers vectors is observed by the dimensional effects of dislocation loops: after irradiation, the applied stress is removed; the whisker shows a residual strain that is due to loops because, after an annealing treatment to evaporate dislocation loops, each whisker recovers its initial straight shape. Everywhere along the whisker, the radius of curvature is measured and plotted vs the max. applied stress. Estimations of the interstitial and vacancy dislocation loop nuclei are derived [fr

Growth rate effects on the formation of dislocation loops around deep helium bubbles in Tungsten

International Nuclear Information System (INIS)

Sandoval, Luis; Perez, Danny; Uberuaga, Blas P.; Voter, Arthur Ford

2016-01-01

Here, the growth process of spherical helium bubbles located 6 nm below a (100) surface is studied using molecular dynamics and parallel replica dynamics simulations, over growth rates from 10"6 to 10"1"2 helium atoms per second. Slower growth rates lead to a release of pressure and lower helium content as compared with fast growth cases. In addition, at slower growth rates, helium bubbles are not decorated by multiple dislocation loops, as these tend to merge or emit given sufficient time. At faster rates, dislocation loops nucleate faster than they can emit, leading to a more complicated dislocation structure around the bubble.

Gauge theory loop operators and Liouville theory

Energy Technology Data Exchange (ETDEWEB)

Drukker, Nadav [Humboldt Univ. Berlin (Germany). Inst. fuer Physik; Gomis, Jaume; Okuda, Takuda [Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada); Teschner, Joerg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

2009-10-15

We propose a correspondence between loop operators in a family of four dimensional N=2 gauge theories on S{sup 4} - including Wilson, 't Hooft and dyonic operators - and Liouville theory loop operators on a Riemann surface. This extends the beautiful relation between the partition function of these N=2 gauge theories and Liouville correlators found by Alday, Gaiotto and Tachikawa. We show that the computation of these Liouville correlators with the insertion of a Liouville loop operator reproduces Pestun's formula capturing the expectation value of a Wilson loop operator in the corresponding gauge theory. We prove that our definition of Liouville loop operators is invariant under modular transformations, which given our correspondence, implies the conjectured action of S-duality on the gauge theory loop operators. Our computations in Liouville theory make an explicit prediction for the exact expectation value of 't Hooft and dyonic loop operators in these N=2 gauge theories. The Liouville loop operators are also found to admit a simple geometric interpretation within quantum Teichmueller theory as the quantum operators representing the length of geodesics. We study the algebra of Liouville loop operators and show that it gives evidence for our proposal as well as providing definite predictions for the operator product expansion of loop operators in gauge theory. (orig.)

Relating loop quantum cosmology to loop quantum gravity: symmetric sectors and embeddings

International Nuclear Information System (INIS)

Engle, J

2007-01-01

In this paper we address the meaning of states in loop quantum cosmology (LQC), in the context of loop quantum gravity. First, we introduce a rigorous formulation of an embedding proposed by Bojowald and Kastrup, of LQC states into loop quantum gravity. Then, using certain holomorphic representations, a new class of embeddings, called b-embeddings, are constructed, following the ideas of Engle (2006 Quantum field theory and its symmetry reduction Class. Quantum Gravity 23 2861-94). We exhibit a class of operators preserving each of these embeddings, and show their consistency with the LQC quantization. In the b-embedding case, the classical analogues of these operators separate points in phase space. Embedding at the gauge and diffeomorphism invariant level is discussed briefly in the conclusions

DNA looping by FokI: the impact of twisting and bending rigidity on protein-induced looping dynamics

Science.gov (United States)

Laurens, Niels; Rusling, David A.; Pernstich, Christian; Brouwer, Ineke; Halford, Stephen E.; Wuite, Gijs J. L.

2012-01-01

Protein-induced DNA looping is crucial for many genetic processes such as transcription, gene regulation and DNA replication. Here, we use tethered-particle motion to examine the impact of DNA bending and twisting rigidity on loop capture and release, using the restriction endonuclease FokI as a test system. To cleave DNA efficiently, FokI bridges two copies of an asymmetric sequence, invariably aligning the sites in parallel. On account of the fixed alignment, the topology of the DNA loop is set by the orientation of the sites along the DNA. We show that both the separation of the FokI sites and their orientation, altering, respectively, the twisting and the bending of the DNA needed to juxtapose the sites, have profound effects on the dynamics of the looping interaction. Surprisingly, the presence of a nick within the loop does not affect the observed rigidity of the DNA. In contrast, the introduction of a 4-nt gap fully relaxes all of the torque present in the system but does not necessarily enhance loop stability. FokI therefore employs torque to stabilise its DNA-looping interaction by acting as a ‘torsional’ catch bond. PMID:22373924

Water loop for training

International Nuclear Information System (INIS)

Moeller, S.V.

1983-02-01

The procedures used to operate the water loop of the Institute of Nuclear Enginering (IEN) in Brazil are presented. The aim is to help future operators of the training water loop in the operation technique and in a better comprehension of the phenomena occured during the execution of an experience. (E.G.) [pt

Loop equations in the theory of gravitation

International Nuclear Information System (INIS)

Makeenko, Yu.M.; Voronov, N.A.

1981-01-01

Loop-space variables (matrices of parallel transport) for the theory of gravitation are described. Loop equations, which are equivalent to the Einstein equations, are derived in the classical case. Loop equations are derived for gravity with cosmological constant as well. An analogy with the loop-space approach in Yang-Mills theory is discussed [ru

Tritium Management Loop Design Status

Energy Technology Data Exchange (ETDEWEB)

Rader, Jordan D. [ORNL; Felde, David K. [ORNL; McFarlane, Joanna [ORNL; Greenwood, Michael Scott [ORNL; Qualls, A L. [ORNL; Calderoni, Pattrick [Idaho National Laboratory (INL)

2017-12-01

This report summarizes physical, chemical, and engineering analyses that have been done to support the development of a test loop to study tritium migration in 2LiF-BeF2 salts. The loop will operate under turbulent flow and a schematic of the apparatus has been used to develop a model in Mathcad to suggest flow parameters that should be targeted in loop operation. The introduction of tritium into the loop has been discussed as well as various means to capture or divert the tritium from egress through a test assembly. Permeation was calculated starting with a Modelica model for a transport through a nickel window into a vacuum, and modifying it for a FLiBe system with an argon sweep gas on the downstream side of the permeation interface. Results suggest that tritium removal with a simple tubular permeation device will occur readily. Although this system is idealized, it suggests that rapid measurement capability in the loop may be necessary to study and understand tritium removal from the system.

Criteria for saturated magnetization loop

International Nuclear Information System (INIS)

Harres, A.; Mikhov, M.; Skumryev, V.; Andrade, A.M.H. de; Schmidt, J.E.; Geshev, J.

2016-01-01

Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe_3O_4 and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

Criteria for saturated magnetization loop

Energy Technology Data Exchange (ETDEWEB)

Harres, A. [Departamento de Física, UFSM, Santa Maria, 97105-900 Rio Grande do Sul (Brazil); Mikhov, M. [Faculty of Physics, University of Sofia, 1164 Sofia (Bulgaria); Skumryev, V. [Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona (Spain); Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Andrade, A.M.H. de; Schmidt, J.E. [Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil); Geshev, J., E-mail: julian@if.ufrgs.br [Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)

2016-03-15

Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe{sub 3}O{sub 4} and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

The Z decay width in the SMEFT: y{sub t} and λ corrections at one loop

Energy Technology Data Exchange (ETDEWEB)

Hartmann, Christine [Niels Bohr International Academy, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Shepherd, William [Niels Bohr International Academy, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Institut für Physik, Johannes-Gutenberg-Universität Mainz,Staudingerweg 7, D-55128 Mainz (Germany); Trott, Michael [Niels Bohr International Academy, University of Copenhagen,Blegdamsvej 17, DK-2100 Copenhagen (Denmark)

2017-03-10

We calculate one loop y{sub t} and λ dependent corrections to Γ̄{sub Z},R̄{sub f}{sup 0} and the partial Z widths due to dimension six operators in the Standard Model Effective Field Theory (SMEFT), including finite terms. We assume CP symmetry and a U(3){sup 5} symmetry in the UV matching onto the dimension six operators, dominantly broken by the Standard Model Yukawa matrices. Corrections to these observables are predicted using the input parameters {α̂_e_w,M̂_Z,Ĝ_F,m̂_t,m̂_h} extracted with one loop corrections in the same limit. We show that at one loop the number of SMEFT parameters contributing to the precise LEPI pseudo-observables exceeds the number of measurements. As a result the SMEFT parameters contributing to LEP data are formally unbounded when the size of loop corrections are reached until other data is considered in a global analysis. The size of these loop effects is generically a correction of order ∼% to leading effects in the SMEFT, but we find multiple large numerical coefficients in our calculation at this order. We use a (MS)-bar scheme, modified for the SMEFT, for renormalization. Some subtleties involving novel evanescent scheme dependence present in this result are explained.

Transforming differential equations of multi-loop Feynman integrals into canonical form

Energy Technology Data Exchange (ETDEWEB)

Meyer, Christoph [Institut für Physik, Humboldt-Universität zu Berlin,12489 Berlin (Germany)

2017-04-03

The method of differential equations has been proven to be a powerful tool for the computation of multi-loop Feynman integrals appearing in quantum field theory. It has been observed that in many instances a canonical basis can be chosen, which drastically simplifies the solution of the differential equation. In this paper, an algorithm is presented that computes the transformation to a canonical basis, starting from some basis that is, for instance, obtained by the usual integration-by-parts reduction techniques. The algorithm requires the existence of a rational transformation to a canonical basis, but is otherwise completely agnostic about the differential equation. In particular, it is applicable to problems involving multiple scales and allows for a rational dependence on the dimensional regulator. It is demonstrated that the algorithm is suitable for current multi-loop calculations by presenting its successful application to a number of non-trivial examples.

Transforming differential equations of multi-loop Feynman integrals into canonical form

Science.gov (United States)

Meyer, Christoph

2017-04-01

The method of differential equations has been proven to be a powerful tool for the computation of multi-loop Feynman integrals appearing in quantum field theory. It has been observed that in many instances a canonical basis can be chosen, which drastically simplifies the solution of the differential equation. In this paper, an algorithm is presented that computes the transformation to a canonical basis, starting from some basis that is, for instance, obtained by the usual integration-by-parts reduction techniques. The algorithm requires the existence of a rational transformation to a canonical basis, but is otherwise completely agnostic about the differential equation. In particular, it is applicable to problems involving multiple scales and allows for a rational dependence on the dimensional regulator. It is demonstrated that the algorithm is suitable for current multi-loop calculations by presenting its successful application to a number of non-trivial examples.

Transforming differential equations of multi-loop Feynman integrals into canonical form

International Nuclear Information System (INIS)

Meyer, Christoph

2017-01-01

The method of differential equations has been proven to be a powerful tool for the computation of multi-loop Feynman integrals appearing in quantum field theory. It has been observed that in many instances a canonical basis can be chosen, which drastically simplifies the solution of the differential equation. In this paper, an algorithm is presented that computes the transformation to a canonical basis, starting from some basis that is, for instance, obtained by the usual integration-by-parts reduction techniques. The algorithm requires the existence of a rational transformation to a canonical basis, but is otherwise completely agnostic about the differential equation. In particular, it is applicable to problems involving multiple scales and allows for a rational dependence on the dimensional regulator. It is demonstrated that the algorithm is suitable for current multi-loop calculations by presenting its successful application to a number of non-trivial examples.

Unexpected Relationships and Inbreeding in HapMap Phase III Populations

Science.gov (United States)

Stevens, Eric L.; Baugher, Joseph D.; Shirley, Matthew D.; Frelin, Laurence P.; Pevsner, Jonathan

2012-01-01

Correct annotation of the genetic relationships between samples is essential for population genomic studies, which could be biased by errors or omissions. To this end, we used identity-by-state (IBS) and identity-by-descent (IBD) methods to assess genetic relatedness of individuals within HapMap phase III data. We analyzed data from 1,397 individuals across 11 ethnic populations. Our results support previous studies (Pemberton et al., 2010; Kyriazopoulou-Panagiotopoulou et al., 2011) assessing unknown relatedness present within this population. Additionally, we present evidence for 1,657 novel pairwise relationships across 9 populations. Surprisingly, significant Cotterman's coefficients of relatedness K1 (IBD1) values were detected between pairs of known parents. Furthermore, significant K2 (IBD2) values were detected in 32 previously annotated parent-child relationships. Consistent with a hypothesis of inbreeding, regions of homozygosity (ROH) were identified in the offspring of related parents, of which a subset overlapped those reported in previous studies (Gibson et al. 2010; Johnson et al. 2011). In total, we inferred 28 inbred individuals with ROH that overlapped areas of relatedness between the parents and/or IBD2 sharing at a different genomic locus between a child and a parent. Finally, 8 previously annotated parent-child relationships had unexpected K0 (IBD0) values (resulting from a chromosomal abnormality or genotype error), and 10 previously annotated second-degree relationships along with 38 other novel pairwise relationships had unexpected IBD2 (indicating two separate paths of recent ancestry). These newly described types of relatedness may impact the outcome of previous studies and should inform the design of future studies relying on the HapMap Phase III resource. PMID:23185369

Capillary-Condenser-Pumped Heat-Transfer Loop

Science.gov (United States)

Silverstein, Calvin C.

1989-01-01

Heat being transferred supplies operating power. Capillary-condenser-pumped heat-transfer loop similar to heat pipe and to capillary-evaporator-pumped heat-transfer loop in that heat-transfer fluid pumped by evaporation and condensation of fluid at heat source and sink, respectively. Capillary condenser pump combined with capillary evaporator pump to form heat exchanger circulating heat-transfer fluids in both loops. Transport of heat more nearly isothermal. Thermal stress in loop reduced, and less external surface area needed in condenser section for rejection of heat to heat sink.

Quantum chromodynamics as dynamics of loops

International Nuclear Information System (INIS)

Makeenko, Yu.; Migdal, A.A.

1980-01-01

The problem of a possibility of reformulating quantum chromodynamics (QCD) in terms of colourless composite fields instead of coloured quarks and gluons is considered. The role of such fields is played by the gauge invariant loop functionals. The Shwinger equations of motion is derived in the loop space which completely describe dynamics of the loop fields. New manifestly gauge invariant diagram technique in the loop space is developed. These diagrams reproduce asymptotic freedom in the ultraviolet range and are consistent with the confinement law in the infrared range

Abnormal duodenal loop demonstrated by X-ray

International Nuclear Information System (INIS)

Thommesen, P.; Funch-Jensen, P.

1986-01-01

The occurrence of dyspeptic symptoms has previously been correlated with the shape of the duodenal loop in patients with X-ray-negative dyspepsia. An abnormal duodenal loop was associated with a significantly higher incidence of symtoms provoked by meals, vomiting, regurgitations, heartburn, and the irritable bowel syndrome. 89% of these patients (26 patients with a normal duodenal loop and 39 patients with abnormal duodenal loop) were available for a 5-year follow-up study of symptomatic outcome. The incidence of symptoms provoked by meals was still significantly higher in patients with an abnormal duodenal loop, and there was also a significant difference concerning symptomatic outcome. Approximately 75% of the patients with a normal duodenal loop had improved, and 25% had unchanged clinical conditions. Approximately 50% of the patients with an abnormal duodenal loop had improved, and 50% had an unchanged or even deteriorated clinical condition

Kalman Orbit Optimized Loop Tracking

Science.gov (United States)

Young, Lawrence E.; Meehan, Thomas K.

2011-01-01

Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

R-loops cause genomic instability in T helper lymphocytes from patients with Wiskott-Aldrich syndrome.

Science.gov (United States)

Sarkar, Koustav; Han, Seong-Su; Wen, Kuo-Kuang; Ochs, Hans D; Dupré, Loïc; Seidman, Michael M; Vyas, Yatin M

2017-12-15

Wiskott-Aldrich syndrome (WAS), X-linked thrombocytopenia (XLT), and X-linked neutropenia, which are caused by WAS mutations affecting Wiskott-Aldrich syndrome protein (WASp) expression or activity, manifest in immunodeficiency, autoimmunity, genomic instability, and lymphoid and other cancers. WASp supports filamentous actin formation in the cytoplasm and gene transcription in the nucleus. Although the genetic basis for XLT/WAS has been clarified, the relationships between mutant forms of WASp and the diverse features of these disorders remain ill-defined. We sought to define how dysfunctional gene transcription is causally linked to the degree of T H cell deficiency and genomic instability in the XLT/WAS clinical spectrum. In human T H 1- or T H 2-skewing cell culture systems, cotranscriptional R-loops (RNA/DNA duplex and displaced single-stranded DNA) and DNA double-strand breaks (DSBs) were monitored in multiple samples from patients with XLT and WAS and in normal T cells depleted of WASp. WASp deficiency provokes increased R-loops and R-loop-mediated DSBs in T H 1 cells relative to T H 2 cells. Mechanistically, chromatin occupancy of serine 2-unphosphorylated RNA polymerase II is increased, and that of topoisomerase 1, an R-loop preventing factor, is decreased at R-loop-enriched regions of IFNG and TBX21 (T H 1 genes) in T H 1 cells. These aberrations accompany increased unspliced (intron-retained) and decreased spliced mRNA of IFNG and TBX21 but not IL13 (T H 2 gene). Significantly, increased cellular load of R-loops and DSBs, which are normalized on RNaseH1-mediated suppression of ectopic R-loops, inversely correlates with disease severity scores. Transcriptional R-loop imbalance is a novel molecular defect causative in T H 1 immunodeficiency and genomic instability in patients with WAS. The study proposes that cellular R-loop load could be used as a potential biomarker for monitoring symptom severity and prognostic outcome in the XLT-WAS clinical spectrum

LOOP: engineering marvel, economic calamity

Energy Technology Data Exchange (ETDEWEB)

Brossard, E B

1985-01-01

The Louisiana Offshore Oil Port (LOOP) is the first superport built in the Lower 48. The United States was the only major oil-importing country that did not have a superport, and therefore, could not offload very large crude carriers (VLCCs). Unfortunately, a number of factors changed after it was decided to build LOOP, and these, plus the onerous provisions of the Deepwater Ports Act of 1974, which authorized superports, prevented LOOP from operating economically. LOOP's facilities consist of an offshore platform complex with three single-point-mooring (SPM) system buoys, 19 miles offshore in 110 feet of water, as well as a 32-million-barrel storage terminal 31 miles inland at Clovelly Salt Dome, and connecting pipelines offshore and onshore. By the time LOOP was started-up in May 1981, demand for oil had declined, because of rises in the price of oil, and the source of US oil imports had shifted back to the western hemisphere, away from the eastern hemisphere, closer to the US. The refinery mix in the US also changed, because of up-grading of a number of big refineries, which further reduced demand and made heavier crudes from countries like Mexico and Venezuela more economical. Because of reduced oil imports and shorter hauls, oil shippers started using or continued to use smaller tankers. Smaller tankers are not economical for LOOP, nor do they need LOOP. The start-up of the Trans-Alaska Pipeline System (TAPS) in mid-1977 backed out 1.5 million bd/sup -1/ of foreign imports. TAPS' capacity coincides with LOOP's offloading capacity of 1.4 million bd/sup -1/. US decontrol of domestic crude in 1981 and increased drilling, plus general energy conservation further reduced US oil imports. US consumption declined to 15.1 million bd/sup -1/ in 1983, from 18.8 million bd/sup -1/ in 1978. This award-winning superport needed federal decontrol and increased oil imports along with more VLCCs, in order to operate economically.

Open loop thanks to direct torque control (DTC). Motor control without feedback loop; Open loop dank direkter Drehmomentregelung (DTC). Hochwertige Motorregelung ohne Rueckfuehrung

Energy Technology Data Exchange (ETDEWEB)

Link, Michael [ABB Automation Products GmbH, Ladenburg (Germany)

2009-07-01

Servo drives are used in various applications. The range of applications is huge and thus also requirements to the drive system. Mainly, a fast torque and speed control is required. This is the domaine of direct torque control (DTC). In many applications DTC can meet this challenge to control the motor with full torque at zero speed. The servo converter based on DTC technology provides a control concept for synchronous and asynchronous motors for both closed loop and open loop control. DTC controlled drives support the whole range from open loop up to high performance motion control applications. (orig.)

Stability, structure, and evolution of cool loops

International Nuclear Information System (INIS)

Cally, P.S.; Robb, T.D.

1991-01-01

The criteria for the existence and stability of cool loops are reexamined. It is found that the stability of the loops strongly depends on the form of the heating and radiative loss functions and that if the Ly-alpha peak which appears in most calculations of the radiative loss function is real, cool loops are almost certainly unstable. Removing the hydrogen contribution from the recent loss function Q(T) by Cook et al. (1989) does not produce the much-used result, Q proportional to T-cubed, which is so favorable to cool loop stability. Even using the probably unrealistically favorable loss function Q1 of Cook et al. with the hydrogen contribution removed, the maximum temperature attainable in stable cool loops is a factor of 2-3 too small to account for the excess emission observed in lower transition region lines. Dynamical simulations of cool loop instabilities reveal that the final state of such a model is the hot loop equilibrium. 26 refs

Conformal anomaly of super Wilson loop

Energy Technology Data Exchange (ETDEWEB)

Belitsky, A.V., E-mail: andrei.belitsky@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)

2012-09-11

Classically supersymmetric Wilson loop on a null polygonal contour possesses all symmetries required to match it onto non-MHV amplitudes in maximally supersymmetric Yang-Mills theory. However, to define it quantum mechanically, one is forced to regularize it since perturbative loop diagrams are not well defined due to presence of ultraviolet divergences stemming from integration in the vicinity of the cusps. A regularization that is adopted by practitioners by allowing one to use spinor helicity formalism, on the one hand, and systematically go to higher orders of perturbation theory is based on a version of dimensional regularization, known as Four-Dimensional Helicity scheme. Recently it was demonstrated that its use for the super Wilson loop at one loop breaks both conformal symmetry and Poincare supersymmetry. Presently, we exhibit the origin for these effects and demonstrate how one can undo this breaking. The phenomenon is alike the one emerging in renormalization group mixing of conformal operators in conformal theories when one uses dimensional regularization. The rotation matrix to the diagonal basis is found by means of computing the anomaly in the Ward identity for the conformal boost. Presently, we apply this ideology to the super Wilson loop. We compute the one-loop conformal anomaly for the super Wilson loop and find that the anomaly depends on its Grassmann coordinates. By subtracting this anomalous contribution from the super Wilson loop we restore its interpretation as a dual description for reduced non-MHV amplitudes which are expressed in terms of superconformal invariants.

Soft Neutrosophic Loops and Their Generalization

Directory of Open Access Journals (Sweden)

Mumtaz Ali

2014-06-01

Full Text Available Soft set theory is a general mathematical tool for dealing with uncertain, fuzzy, not clearly defined objects. In this paper we introduced soft neutrosophic loop,soft neutosophic biloop, soft neutrosophic N -loop with the discuission of some of their characteristics. We also introduced a new type of soft neutrophic loop, the so called soft strong neutrosophic loop which is of pure neutrosophic character. This notion also found in all the other corresponding notions of soft neutrosophic thoery. We also given some of their properties of this newly born soft structure related to the strong part of neutrosophic theory.

Two- and three-loop amplitudes in covariant loop calculus

International Nuclear Information System (INIS)

Roland, K.

1988-04-01

We study 2- and 3-loop vacuum-amplitudes for the closed bosonic string. We compare two sets of expressions for the corresponding density on moduli space: One, based on the covariant Reggeon loop calculus (where modular invariance is not manifest). The other, based on analytic geometry. We want to prove identity between the two sets of expressions. Quite apart from demonstrating modular invariance of the Reggeon results, this would in itself be a remarkable mathematical feature. Identity is established to 'high' order in some moduli and exactly in others. The expansions reveal an essentially number-theoretical structure. Agreement is found only by exploiting the connection between the 4 Jacobi θ-functions and number theory. (orig.)

Two- and three-loop amplitudes in covariant loop calculus

International Nuclear Information System (INIS)

Roland, K.

1989-01-01

We study two- and three-loop vacuum amplitudes for the closed bosonic string. We compare two sets of expressions for the corresponding density on moduli space. One is based on the covariant reggeon loop calculus (where modular invariance is not manifest). The other is based on analytic geometry. We want to prove identity between the two sets of expressions. Quite apart from demonstrating modular invariance of the reggeon results, this would in itself be a remarkable mathematical feature. Identity is established to ''high'' order in some moduli and exactly in others. The expansions reveal an essentially number-theoretic structure. Agreement is found only by exploiting the connection between the four Jacobi θ-functions and number theory. (orig.)

High-temperature helium-loop facility

International Nuclear Information System (INIS)

Tokarz, R.D.

1981-09-01

The high-temperature helium loop is a facility for materials testing in ultrapure helium gas at high temperatures. The closed loop system is capable of recirculating high-purity helium or helium with controlled impurities. The gas loop maximum operating conditions are as follows: 300 psi pressure, 500 lb/h flow rate, and 2100 0 F temperature. The two test sections can accept samples up to 3.5 in. diameter and 5 ft long. The gas loop is fully instrumented to continuously monitor all parameters of loop operation as well as helium impurities. The loop is fully automated to operate continuously and requires only a daily servicing by a qualified operator to replenish recorder charts and helium makeup gas. Because of its versatility and high degree of parameter control, the helium loop is applicable to many types of materials research. This report describes the test apparatus, operating parameters, peripheral systems, and instrumentation system. The experimental capabilities and test conand presents the results that have been obtained. The study has been conducted using a four-phase approach. The first phase develops the solution to the steady-state radon-diffusion equation in one-dimensieered barriers; disposal charge analysis; analysis of spent fuel policy implementation; spent f water. Field measurements and observations are reported for each site. Analytical data and field measurements are presented in tables and maps. Uranium concentrations in the sediments which were above detection limits ranged from 0.10 t 51.2 ppM. The mean of the logarithms of the uranium concentrations was 0.53. A group of high uranium concentrations occurs near the junctions of quadrangles AB, AC, BB, a 200 mK. In case 2), x-ray studies of isotopic phase separation in 3 He-- 4 He bcc solids were carried out by B. A. Fraass

Loop Quantum Gravity

Directory of Open Access Journals (Sweden)

Rovelli Carlo

1998-01-01

Full Text Available The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii A derivation of the Bekenstein-Hawking black hole entropy formula. (iii An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

Estimation of complex permittivity using loop antenna

DEFF Research Database (Denmark)

Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

2004-01-01

A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna.......A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna....

Functional Fourier transforms and the loop equation

International Nuclear Information System (INIS)

Bershadskii, M.A.; Vaisburd, I.D.; Migdal, A.A.

1986-01-01

The Migdal-Makeenko momentum-space loop equation is investigated. This equation is derived from the ordinary loop equation by taking the Fourier transform of the Wilson functional. A perturbation theory is constructed for the new equation and it is proved that the action of the loop operator is determined by vertex functions which coincide with those of the previous equation. It is shown how the ghost loop arises in direct iterations of the momentum-space equation with respect to the coupling constant. A simple example is used to illustrate the mechanism of appearance of an integration in the interior loops in transition to observables

Loop Evolution Observed with AIA and Hi-C

Science.gov (United States)

Mulu-Moore, Fana; Winebarger, Amy R.; Cirtain, Jonathan W.; Kobayashi, Ken; Korreck, Kelly E.; Golub, Leon; Kuzin, Sergei; Walsh, Robert William; DeForest, Craig E.; De Pontieu, Bart;

First cytoplasmic loop of glucagon-like peptide-1 receptor can function at the third cytoplasmic loop position of rhodopsin.

Science.gov (United States)

Yamashita, Takahiro; Tose, Koji; Shichida, Yoshinori

2008-01-01

G protein-coupled receptors (GPCRs) are classified into several families based on their amino acid sequences. In family 1, GPCRs such as rhodopsin and adrenergic receptor, the structure-function relationship has been extensively investigated to demonstrate that exposure of the third cytoplasmic loop is essential for selective G protein activation. In contrast, much less is known about other families. Here we prepared chimeric mutants between Gt-coupled rhodopsin and Gi/Go- and Gs-coupled glucagon-like peptide-1 (GLP-1) receptor of family 2 and tried to identify the loop region that functions at the third cytoplasmic loop position of rhodopsin. We succeeded in expressing a mutant having the first cytoplasmic loop of GLP-1 receptor and found that this mutant activated Gi and Go efficiently but did not activate Gt. Moreover, the rhodopsin mutant having the first loop of Gs-coupled secretin receptor of family 2 decreased the Gi and Go activation efficiencies. Therefore, the first loop of GLP-1 receptor would share a similar role to the third loop of rhodopsin in G protein activation. This result strongly suggested that different families of GPCRs have maintained molecular architectures of their ancestral types to generate a common mechanism, namely exposure of the cytoplasmic loop, to activate peripheral G protein.

High pressure experimental water loop

International Nuclear Information System (INIS)

Grenon, M.

1958-01-01

A high pressure experimental water loop has been made for studying the detection and evolution of cladding failure in a pressurized reactor. The loop has been designed for a maximum temperature of 360 deg. C, a maximum of 160 kg/cm 2 and flow rates up to 5 m 3 /h. The entire loop consists of several parts: a main circuit with a canned rotor circulation pump, steam pressurizer, heating tubes, two hydro-cyclones (one de-gasser and one decanter) and one tubular heat exchanger; a continuous purification loop, connected in parallel, comprising pressure reducing valves and resin pots which also allow studies of the stability of resins under pressure, temperature and radiation; following the gas separator is a gas loop for studying the recombination of the radiolytic gases in the steam phase. The preceding circuits, as well as others, return to a low pressure storage circuit. The cold water of the low pressure storage flask is continuously reintroduced into the high pressure main circuit by means of a return pump at a maximum head of 160 kg /cm 2 , and adjusted to the pressurizer level. This loop is also a testing bench for the tight high pressure apparatus. The circulating pump and the connecting flanges (Oak Ridge type) are water-tight. The feed pump and the pressure reducing valves are not; the un-tight ones have a system of leak recovery. To permanently check the tightness the circuit has been fitted with a leak detection system (similar to the HRT one). (author) [fr

Niveles y efectos de la consanguinidad en variables de comportamiento durante la tienta y la lidia en dos ganaderías de reses bravas de Colombia Levels and effects of inbreeding on performance traits during tempt and fight from two fighting bull farms in Colombia

Directory of Open Access Journals (Sweden)

David Calero Quintero

2010-04-01

Full Text Available En el estudio se estimaron los niveles y las tendencias de la consanguinidad en variables de comportamiento durante la tienta y la lidia en dos ganaderías colombianas de reses bravas: Ernesto González Caicedo (EGC - Popayán, Cauca, encaste Santacoloma; y Guachicono (GUA - Bolívar, Cauca, Colombia, encaste Parladé. Se analizaron los pedigríes de 2.094 animales EGC nacidos entre 1918 y 2007 y 963 GUA, nacidos entre 1928 y 2005. Los coeficientes de consanguinidad de los bovinos se obtuvieron usando el Proc Inbreed del programa SAS v. 9.1.3. Se estudiaron además de las notas del ganadero, las variables propias y comunes a las faenas de tienta y de lidia. Los promedios y las desviaciones estándar de la consanguinidad en EGC y GUA fueron 4.9±6.6 y 4.2±4.2% para todos los animales, 4.5±5.8 y 6.0±3.4% para la última época estudiada, y 10.6±5.8 y 6.5±3.5% considerando sólo los consanguíneos. Se encontraron efectos positivos en las variables responsables de ‘toreabilidad’ y estilo, y depresivos en la fuerza de los animales. La consanguinidad actual en ambas ganaderías es mediana, sin embargo debe diseñarse un plan de apareamiento.This study was carried out to estimate levels and trends of the inbreeding on behavior variables during the tempt and fight from two fighting farms: Ernesto González Caicedo (EGC and Guachicono (GUA with strains Santacoloma, and Parladé respectively, located on Popayán and Bolívar, municipalities of the Cauca Department, Colombia. The pedigrees of 2094 EGC animals born between 1918 and 2007, and 963 GUA animals born between 1928 and 2005 were analyzed. Inbreeding coefficients of the cattle were obtained using PROC INBREED from the software SAS v. 9.1.3. In addition to the breeder’s notes the own variables, dealing and common to the tempt and fight task were studied. The average and standard deviations of the blood relationship during the total and the last time studied for the cattle raising EGC and

Use of multiple objective evolutionary algorithms in optimizing surveillance requirements

International Nuclear Information System (INIS)

Martorell, S.; Carlos, S.; Villanueva, J.F.; Sanchez, A.I; Galvan, B.; Salazar, D.; Cepin, M.

2006-01-01

This paper presents the development and application of a double-loop Multiple Objective Evolutionary Algorithm that uses a Multiple Objective Genetic Algorithm to perform the simultaneous optimization of periodic Test Intervals (TI) and Test Planning (TP). It takes into account the time-dependent effect of TP performed on stand-by safety-related equipment. TI and TP are part of the Surveillance Requirements within Technical Specifications at Nuclear Power Plants. It addresses the problem of multi-objective optimization in the space of dependable variables, i.e. TI and TP, using a novel flexible structure of the optimization algorithm. Lessons learnt from the cases of application of the methodology to optimize TI and TP for the High-Pressure Injection System are given. The results show that the double-loop Multiple Objective Evolutionary Algorithm is able to find the Pareto set of solutions that represents a surface of non-dominated solutions that satisfy all the constraints imposed on the objective functions and decision variables. Decision makers can adopt then the best solution found depending on their particular preference, e.g. minimum cost, minimum unavailability

Automation of loop amplitudes in numerical approach

International Nuclear Information System (INIS)

Fujimoto, J.; Ishikawa, T.; Shimizu, Y.; Kato, K.; Nakazawa, N.; Kaneko, T.

1997-01-01

An automatic calculating system GRACE-L1 of one-loop Feynman amplitude is reviewed. This system can be applied to 2 to 2-body one-loop processes. A sample calculation of 2 to 3-body one-loop amplitudes is also presented. (orig.)

Loop-quantum-gravity vertex amplitude.

Science.gov (United States)

Engle, Jonathan; Pereira, Roberto; Rovelli, Carlo

2007-10-19

Spin foam models are hoped to provide the dynamics of loop-quantum gravity. However, the most popular of these, the Barrett-Crane model, does not have the good boundary state space and there are indications that it fails to yield good low-energy n-point functions. We present an alternative dynamics that can be derived as a quantization of a Regge discretization of Euclidean general relativity, where second class constraints are imposed weakly. Its state space matches the SO(3) loop gravity one and it yields an SO(4)-covariant vertex amplitude for Euclidean loop gravity.

Bootstrapping the Three-Loop Hexagon

Energy Technology Data Exchange (ETDEWEB)

Dixon, Lance J.; /CERN /SLAC; Drummond, James M.; /CERN /Annecy, LAPTH; Henn, Johannes M.; /Humboldt U., Berlin /Santa Barbara, KITP

2011-11-08

We consider the hexagonal Wilson loop dual to the six-point MHV amplitude in planar N = 4 super Yang-Mills theory. We apply constraints from the operator product expansion in the near-collinear limit to the symbol of the remainder function at three loops. Using these constraints, and assuming a natural ansatz for the symbol's entries, we determine the symbol up to just two undetermined constants. In the multi-Regge limit, both constants drop out from the symbol, enabling us to make a non-trivial confirmation of the BFKL prediction for the leading-log approximation. This result provides a strong consistency check of both our ansatz for the symbol and the duality between Wilson loops and MHV amplitudes. Furthermore, we predict the form of the full three-loop remainder function in the multi-Regge limit, beyond the leading-log approximation, up to a few constants representing terms not detected by the symbol. Our results confirm an all-loop prediction for the real part of the remainder function in multi-Regge 3 {yields} 3 scattering. In the multi-Regge limit, our result for the remainder function can be expressed entirely in terms of classical polylogarithms. For generic six-point kinematics other functions are required.

Lattice QED in the loop space

International Nuclear Information System (INIS)

Fort, H.

1994-01-01

We present a survey on the state of the art in the formulation of lattice compact QED in the space of loops. In a first part we review our most recent Hamiltonian results which signal a second order transition for (3+1) compact QED. We devote the second part to the Lagrangian loop formalism, showing the equivalence of the recently proposed loop action with the Villain form. (orig.)

Loop quantization as a continuum limit

International Nuclear Information System (INIS)

Manrique, Elisa; Oeckl, Robert; Weber, Axel; Zapata, Jose A

2006-01-01

We present an implementation of Wilson's renormalization group and a continuum limit tailored for loop quantization. The dynamics of loop-quantized theories is constructed as a continuum limit of the dynamics of effective theories. After presenting the general formalism we show as a first explicit example the 2D Ising field theory, an interacting relativistic quantum field theory with local degrees of freedom quantized by loop quantization techniques

Flat Knitting Loop Deformation Simulation Based on Interlacing Point Model

Directory of Open Access Journals (Sweden)

Jiang Gaoming

2017-12-01

Full Text Available In order to create realistic loop primitives suitable for the faster CAD of the flat-knitted fabric, we have performed research on the model of the loop as well as the variation of the loop surface. This paper proposes an interlacing point-based model for the loop center curve, and uses the cubic Bezier curve to fit the central curve of the regular loop, elongated loop, transfer loop, and irregular deformed loop. In this way, a general model for the central curve of the deformed loop is obtained. The obtained model is then utilized to perform texture mapping, texture interpolation, and brightness processing, simulating a clearly structured and lifelike deformed loop. The computer program LOOP is developed by using the algorithm. The deformed loop is simulated with different yarns, and the deformed loop is applied to design of a cable stitch, demonstrating feasibility of the proposed algorithm. This paper provides a loop primitive simulation method characterized by lifelikeness, yarn material variability, and deformation flexibility, and facilitates the loop-based fast computer-aided design (CAD of the knitted fabric.

Variational solution of the loop equation in QCD

International Nuclear Information System (INIS)

Agishtein, M.E.; Migdal, A.A.

1988-01-01

A new technique for the large N loop equation of QCD is worked out. The Wilson loop W(C) is approximated by a Gaussian functional. The parameters are fitted to the loop equation, after which the equation is statisfied up to 0.2%. The resulting Wilson loop corresponds to linearly rising Regge trajectories. The problem of tachyon is still present, but it could be cured by iteration of the loop equation starting from this variational solution. (orig.)

Variational solution of the loop equation in QCD

International Nuclear Information System (INIS)

Agishtein, M.E.; Migdal, A.A.

1988-01-01

A new technique for the large N loop equation of QCD is worked out. The Wilson loop W(C) is approximated by a Gaussian functional. The parameters are fitted to the loop equation, after which the equation is satisfied up to 0.2%. The resulting Wilson loop corresponds to linearly rising Regge trajectories. The problem of tachyon is still present, but it could be cured by iteration of the loop equation starting from this variational solution

Loop Quantum Cosmology

Directory of Open Access Journals (Sweden)

Bojowald Martin

2008-07-01

Full Text Available Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.

Loop Quantum Cosmology

Directory of Open Access Journals (Sweden)

Bojowald Martin

2005-12-01

Full Text Available Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new kinds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.

Inventory decision in a closed-loop supply chain with inspection, sorting, and waste disposal

Science.gov (United States)

Dwicahyani, A. R.; Jauhari, W. A.; Kurdhi, N. A.

2016-02-01

The study of returned item inventory management in a closed-loop supply chain system has become an important issue in recent years. So far, investigations about inventory decision making in a closed-loop supply chain system have been confined to traditional forward and reverse oriented material flow supply chain. In this study, we propose an integrated inventory model consisting a supplier, a manufacturer, and a retailer where the manufacturer inspects all of the returned items collected from the customers and classifies them as recoverable or waste. Returned items that recovered through the remanufacturing process and the newly manufactured products are then used to meet the demand of the retailer. However, some recovered items which are not comparable to the ones in quality, classified as refurbished items, are sold to a secondary market at a reduced price. This study also suggests that the flow of returned items is controlled by a decision variable, namely an acceptance quality level of recoverable item in the system. We apply multiple remanufacturing cycle and multiple production cycle policy to the proposed model and give the corresponding iterative procedure to determine the optimal solutions. Further, numerical examples are presented for illustrative purpose.

CHY loop integrands from holomorphic forms

Energy Technology Data Exchange (ETDEWEB)

Gomez, Humberto [Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia); Perimeter Institute for Theoretical Physics,31 Caroline Street N, Waterloo, ON N2L 2Y5 (Canada); Mizera, Sebastian; Zhang, Guojun [Perimeter Institute for Theoretical Physics,31 Caroline Street N, Waterloo, ON N2L 2Y5 (Canada); Department of Physics & Astronomy, University of Waterloo,Waterloo, ON N2L 3G1 (Canada)

2017-03-16

Recently, the Cachazo-He-Yuan (CHY) approach for calculating scattering amplitudes has been extended beyond tree level. In this paper, we introduce a way of constructing CHY integrands for Φ{sup 3} theory up to two loops from holomorphic forms on Riemann surfaces. We give simple rules for translating Feynman diagrams into the corresponding CHY integrands. As a complementary result, we extend the L-algorithm, originally introduced in https://arxiv.org/abs/1604.05373, to two loops. Using this approach, we are able to analytically verify our prescription for the CHY integrands up to seven external particles at two loops. In addition, it gives a natural way of extending to higher-loop orders.

Systematic determination of the mosaic structure of bacterial genomes: species backbone versus strain-specific loops

Directory of Open Access Journals (Sweden)

Gendrault-Jacquemard A

2005-07-01

Full Text Available Abstract Background Public databases now contain multitude of complete bacterial genomes, including several genomes of the same species. The available data offers new opportunities to address questions about bacterial genome evolution, a task that requires reliable fine comparison data of closely related genomes. Recent analyses have shown, using pairwise whole genome alignments, that it is possible to segment bacterial genomes into a common conserved backbone and strain-specific sequences called loops. Results Here, we generalize this approach and propose a strategy that allows systematic and non-biased genome segmentation based on multiple genome alignments. Segmentation analyses, as applied to 13 different bacterial species, confirmed the feasibility of our approach to discern the 'mosaic' organization of bacterial genomes. Segmentation results are available through a Web interface permitting functional analysis, extraction and visualization of the backbone/loops structure of documented genomes. To illustrate the potential of this approach, we performed a precise analysis of the mosaic organization of three E. coli strains and functional characterization of the loops. Conclusion The segmentation results including the backbone/loops structure of 13 bacterial species genomes are new and available for use by the scientific community at the URL: http://genome.jouy.inra.fr/mosaic.

Loop quantum cosmology and singularities.

Science.gov (United States)

Struyve, Ward

2017-08-15

Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of so-called loop quantum cosmology which concerns symmetry-reduced models of quantum gravity. In this paper, the problem of singularities is analysed in the context of the Bohmian formulation of loop quantum cosmology. In this formulation there is an actual metric in addition to the wave function, which evolves stochastically (rather than deterministically as the case of the particle evolution in non-relativistic Bohmian mechanics). Thus a singularity occurs whenever this actual metric is singular. It is shown that in the loop quantum cosmology for a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker space-time with arbitrary constant spatial curvature and cosmological constant, coupled to a massless homogeneous scalar field, a big bang or big crunch singularity is never obtained. This should be contrasted with the fact that in the Bohmian formulation of the Wheeler-DeWitt theory singularities may exist.

Liquid Lead-Bismuth Materials Test Loop

International Nuclear Information System (INIS)

Tcharnotskaia, Valentina; Ammerman, Curtt; Darling, Timothy; King, Joe; Li, Ning; Shaw, Don; Snodgrass, Leon; Woloshun, Keith

2002-01-01

We designed and built the Liquid Lead-Bismuth Materials Test Loop (MTL) to study the materials behavior in a flow of molten lead-bismuth eutectic (LBE). In this paper we present a description of the loop with main components and their functions. Stress distribution in the piping due to sustained, occasional and expansion loads is shown. The loop is designed so that a difference of 100 deg. C can be attained between the coldest and the hottest parts at a nominal flow rate of 8.84 GPM. Liquid LBE flow can be activated by a mechanical sump pump or by natural convection. In order to maintain a self-healing protective film on the surface of the stainless steel pipe, a certain concentration of oxygen has to be maintained in the liquid metal. We developed oxygen sensors and an oxygen control system to be implemented in the loop. The loop is outfitted with a variety of instruments that are controlled from a computer based data acquisition system. Initial experiments include preconditioning the loop, filling it up with LBE, running at uniform temperature and tuning the oxygen control system. We will present some preliminary results and discuss plans for the future tests. (authors)

Towards an Artificial Phonological Loop: An Assistive Device for Working Memory and Attentional Control

Directory of Open Access Journals (Sweden)

D. Bogen

2006-01-01

Full Text Available We describe the initial development of an artificial phonological loop (APL, a new technology to assist individuals with impairment of the working memory system. The phonological loop, along with the visuospatial sketchpad, is one of the two slave short-term memory subsystems that comprise working memory, a cognitive function closely associated with the control of attention. In the phonological loop, phonological (speech information lasting for 1–2 second is maintained active by repetitive, subvocal (silent speech rehearsal. Deficits in working memory, specifically in the phonological loop, occur in many disorders, including attention-deficit disorder and Alzheimer’s disease. In these disorders, it appears that the ability for phonological rehearsal is intact, but the regulation or triggering of the rehearsal process is inadequate, thus causing the contents of working memory to be lost. The purpose, then, of the APL is to facilitate the phonological loop by artificially extending the duration of phonological rehearsals. The APL mimics the natural phonological loop by providing audible vocal echoes to take the place of subvocal rehearsals. In this system, the user talks to him/herself in short (1–2 second phrases; the device records these phrases, stores them in electronic memory, and then repeats— i.e., echoes—the phrases multiple times over an extended period. Two versions of this device have been developed: the Echo-APL and the Rearticulation-APL. In the Echo-APL, only echoing is involved. In the Rearticulation-APL, however, the user re-vocalizes (rearticulates the phrase in response to an audible cue. The device repeats the cue until it detects (hears the re-vocalization. Future research and development of the APL will require extensive testing and careful evaluation of possible echo-schedules: the predefined program controlling inter-echo time intervals and echo-amplitude (echo loudness. The APL essentially exteriorizes the silent

Efeito da endogamia na produção de sementes de pepino caipira Effect of inbreeding in seeds yield of "caipira" cucumber

Directory of Open Access Journals (Sweden)

Amanda Regina Godoy

2006-01-01

Full Text Available Este trabalho teve por objetivo verificar se existe depressão por endogamia para produção de sementes com sucessivas gerações de autofecundações em uma população de pepino caipira, obtida a partir da geração F2 do cruzamento (Safira x Hatem x Safira. O delineamento experimental utilizado foi em blocos ao acaso, com seis tratamentos (diferentes gerações de autofecundação - S0 a S5, quatro repetições e cinco plantas por parcela. Não houve diferença estatística para todas as características avaliadas (número de frutos por planta, massa de sementes por planta, massa de sementes por fruto, número de sementes por planta, número de sementes por fruto, massa de 100 sementes, teste-padrão de germinação, primeira contagem do teste-padrão de germinação e índice de velocidade de germinação, observando-se que a endogamia não afetou a produção e qualidade das sementes nessa população.The objective of this work was to evaluate the inbreeding depression after successive generations of self-pollination in a cucumber population, generation F2 from the cross (Safira x Hatem x Safira. Experimental design was randomized blocks with six treatments (different generations of self-pollination - S0 to S5, four replicates and five plants per plot. There was no statistical difference among all evauated characteristics (fruit number per plant, number and weight of seeds per plant and per fruit, germination test, first count of germinated seeds, index of germination a and weight of 100 seeds, showing that inbreeding did not affect seed production and quality in this population.

The four-loop six-gluon NMHV ratio function

Energy Technology Data Exchange (ETDEWEB)

Dixon, Lance J. [SLAC National Accelerator Lab., Stanford, CA (United States); California Inst. of Technology (CalTech), Pasadena, CA (United States); von Hippel, Matt [Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada); McLeod, Andrew J. [SLAC National Accelerator Lab., Stanford, CA (United States)

2016-01-11

We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N = 4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q^- differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We test the result against multi- Regge predictions at NNLL and N³LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We also study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. Furthermore, we provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.

The four-loop six-gluon NMHV ratio function

Energy Technology Data Exchange (ETDEWEB)

Dixon, Lance J. [SLAC National Accelerator Laboratory, Stanford University,Stanford, CA 94309 (United States); Walter Burke Institute for Theoretical Physics, California Institute of Technology,Pasadena, CA 91125 (United States); Hippel, Matt von [Perimeter Institute for Theoretical Physics,Waterloo, Ontario N2L 2Y5 (Canada); McLeod, Andrew J. [SLAC National Accelerator Laboratory, Stanford University,Stanford, CA 94309 (United States)

2016-01-11

We use the hexagon function bootstrap to compute the ratio function which characterizes the next-to-maximally-helicity-violating (NMHV) six-point amplitude in planar N=4 super-Yang-Mills theory at four loops. A powerful constraint comes from dual superconformal invariance, in the form of a Q̄ differential equation, which heavily constrains the first derivatives of the transcendental functions entering the ratio function. At four loops, it leaves only a 34-parameter space of functions. Constraints from the collinear limits, and from the multi-Regge limit at the leading-logarithmic (LL) and next-to-leading-logarithmic (NLL) order, suffice to fix these parameters and obtain a unique result. We test the result against multi-Regge predictions at NNLL and N{sup 3}LL, and against predictions from the operator product expansion involving one and two flux-tube excitations; all cross-checks are satisfied. We study the analytical and numerical behavior of the parity-even and parity-odd parts on various lines and surfaces traversing the three-dimensional space of cross ratios. As part of this program, we characterize all irreducible hexagon functions through weight eight in terms of their coproduct. We also provide representations of the ratio function in particular kinematic regions in terms of multiple polylogarithms.

The four-loop remainder function and multi-Regge behavior at NNLLA in planar N=4 super-Yang-Mills theory

Energy Technology Data Exchange (ETDEWEB)

Dixon, Lance J. [SLAC National Accelerator Laboratory,Stanford University, Stanford, CA 94309 (United States); Drummond, James M. [CERN,Geneva 23 (Switzerland); School of Physics and Astronomy, University of Southampton,Highfield, Southampton, SO17 1BJ (United Kingdom); LAPTH, CNRS et Université de Savoie,F-74941 Annecy-le-Vieux Cedex (France); Duhr, Claude [Institute for Particle Physics Phenomenology, University of Durham,Durham, DH1 3LE (United Kingdom); Pennington, Jeffrey [SLAC National Accelerator Laboratory,Stanford University, Stanford, CA 94309 (United States)

2014-06-19

We present the four-loop remainder function for six-gluon scattering with maximal helicity violation in planar N=4 super-Yang-Mills theory, as an analytic function of three dual-conformal cross ratios. The function is constructed entirely from its analytic properties, without ever inspecting any multi-loop integrand. We employ the same approach used at three loops, writing an ansatz in terms of hexagon functions, and fixing coefficients in the ansatz using the multi-Regge limit and the operator product expansion in the near-collinear limit. We express the result in terms of multiple polylogarithms, and in terms of the coproduct for the associated Hopf algebra. From the remainder function, we extract the BFKL eigenvalue at next-to-next-to-leading logarithmic accuracy (NNLLA), and the impact factor at N{sup 3}LLA. We plot the remainder function along various lines and on one surface, studying ratios of successive loop orders. As seen previously through three loops, these ratios are surprisingly constant over large regions in the space of cross ratios, and they are not far from the value expected at asymptotically large orders of perturbation theory.

Loop-Loop Interactions Regulate KaiA-Stimulated KaiC Phosphorylation in the Cyanobacterial KaiABC Circadian Clock

Energy Technology Data Exchange (ETDEWEB)

Egli, Martin [Vanderbilt Univ., Nashville, TN (United States); Pattanayek, Rekha [Vanderbilt Univ., Nashville, TN (United States); Sheehan, Jonathan H. [Vanderbilt Univ., Nashville, TN (United States); Xu, Yao [Vanderbilt Univ., Nashville, TN (United States); Mori, Tetsuya [Vanderbilt Univ., Nashville, TN (United States); Smith, Jarrod A. [Vanderbilt Univ., Nashville, TN (United States); Johnson, Carl H. [Vanderbilt Univ., Nashville, TN (United States)

2013-01-25

We found that the Synechococcus elongatus KaiA, KaiB, and KaiC proteins in the presence of ATP generate a post-translational oscillator that runs in a temperature-compensated manner with a period of 24 h. KaiA dimer stimulates phosphorylation of KaiC hexamer at two sites per subunit, T432 and S431, and KaiB dimers antagonize KaiA action and induce KaiC subunit exchange. Neither the mechanism of KaiA-stimulated KaiC phosphorylation nor that of KaiB-mediated KaiC dephosphorylation is understood in detail at present. We demonstrate here that the A422V KaiC mutant sheds light on the former mechanism. It was previously reported that A422V is less sensitive to dark pulse-induced phase resetting and has a reduced amplitude of the KaiC phosphorylation rhythm in vivo. A422 maps to a loop (422-loop) that continues toward the phosphorylation sites. By pulling on the C-terminal peptide of KaiC (A-loop), KaiA removes restraints from the adjacent 422-loop whose increased flexibility indirectly promotes kinase activity. We found in the crystal structure that A422V KaiC lacks phosphorylation at S431 and exhibits a subtle, local conformational change relative to wild-type KaiC. Molecular dynamics simulations indicate higher mobility of the 422-loop in the absence of the A-loop and mobility differences in other areas associated with phosphorylation activity between wild-type and mutant KaiCs. Finally, the A-loop–422-loop relay that informs KaiC phosphorylation sites of KaiA dimer binding propagates to loops from neighboring KaiC subunits, thus providing support for a concerted allosteric mechanism of phosphorylation.

Two-phase Heating in Flaring Loops

Science.gov (United States)

Zhu, Chunming; Qiu, Jiong; Longcope, Dana W.

2018-03-01

We analyze and model a C5.7 two-ribbon solar flare observed by the Solar Dynamics Observatory, Hinode, and GOES on 2011 December 26. The flare is made of many loops formed and heated successively over one and half hours, and their footpoints are brightened in the UV 1600 Å before enhanced soft X-ray and EUV missions are observed in flare loops. Assuming that anchored at each brightened UV pixel is a half flaring loop, we identify more than 6700 half flaring loops, and infer the heating rate of each loop from the UV light curve at the footpoint. In each half loop, the heating rate consists of two phases: intense impulsive heating followed by a low-rate heating that is persistent for more than 20 minutes. Using these heating rates, we simulate the evolution of their coronal temperatures and densities with the model of the “enthalpy-based thermal evolution of loops.” In the model, suppression of thermal conduction is also considered. This model successfully reproduces total soft X-ray and EUV light curves observed in 15 passbands by four instruments GOES, AIA, XRT, and EVE. In this flare, a total energy of 4.9 × 1030 erg is required to heat the corona, around 40% of this energy is in the slow-heating phase. About two-fifths of the total energy used to heat the corona is radiated by the coronal plasmas, and the other three fifth transported to the lower atmosphere by thermal conduction.

Control-structure interaction in precision pointing servo loops

Science.gov (United States)

Spanos, John T.

1989-01-01

The control-structure interaction problem is addressed via stability analysis of a generic linear servo loop model. With the plant described by the rigid body mode and a single elastic mode, structural flexibility is categorized into one of three types: (1) appendage, (2) in-the-loop minimum phase, and (3) in-the-loop nonminimum phase. Closing the loop with proportional-derivative (PD) control action and introducing sensor roll-off dynamics in the feedback path, stability conditions are obtained. Trade studies are conducted with modal frequency, modal participation, modal damping, loop bandwidth, and sensor bandwidth treated as free parameters. Results indicate that appendage modes are most likely to produce instability if they are near the sensor rolloff, whereas in-the-loop modes are most dangerous near the loop bandwidth. The main goal of this paper is to provide a fundamental understanding of the control-structure interaction problem so that it may benefit the design of complex spacecraft and pointing system servo loops. In this framework, the JPL Pathfinder gimbal pointer is considered as an example.

Numerical evaluation of one-loop QCD amplitudes

DEFF Research Database (Denmark)

Badger, Simon David; Biedermann, Benedikt; Uwer, Peter

2012-01-01

We present the publicly available program NGluon allowing the numerical evaluation of primitive amplitudes at one-loop order in massless QCD. The program allows the computation of one-loop amplitudes for an arbitrary number of gluons. The focus of the present article is the extension to one-loop ...

Vertically Polarized Omnidirectional Printed Slot Loop Antenna

DEFF Research Database (Denmark)

Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper

2015-01-01

A novel vertically polarized omnidirectional printed slot loop antenna has been designed, simulated, fabricated and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform and in-phase fields in the slot in order to obtain an omnidirectional radiation...... pattern. The antenna is designed for the 2.45 GHz Industrial, Scientific and Medical band. Applications of the antenna are many. One is for on-body applications since it is ideal for launching a creeping waves due to the polarization....

Measurement of kinetic inductance of superconducting wires and application for measuring flux state of Josephson-junction loops

Energy Technology Data Exchange (ETDEWEB)

Shimazu, Y.; Yokoyama, T

2004-10-01

In order to realize strong coupling in a system of multiple flux qubits with a DC-SQUID, the use of kinetic inductance is advantageous because it can be much larger than geometrical inductance for narrow superconducting wires. We measured the inductance associated with narrow Al wires, and estimated the contributions of kinetic and geometrical inductances. The London penetration depth which determines the kinetic inductance is evaluated. We fabricated samples of two Josephson-junction loops and a DC-SQUID which are all coupled with kinetic inductances. The observed magnetic flux due to the loops is in good agreement with the result of numerical simulation based on the estimated inductances.

String breaking with Wilson loops?

CERN Document Server

Kratochvila, S; Kratochvila, Slavo; Forcrand, Philippe de

2003-01-01

A convincing, uncontroversial observation of string breaking, when the static potential is extracted from Wilson loops only, is still missing. This failure can be understood if the overlap of the Wilson loop with the broken string is exponentially small. In that case, the broken string ground state will only be seen if the Wilson loop is long enough. Our preliminary results show string breaking in the context of the 3d SU(2) adjoint static potential, using the L\\"uscher-Weisz exponential variance reduction approach. As a by-product, we measure the fundamental SU(2) static potential with improved accuracy and see clear deviations from Casimir scaling.

BMN correlators by loop equations

International Nuclear Information System (INIS)

Eynard, Bertrand; Kristjansen, Charlotte

2002-01-01

In the BMN approach to N=4 SYM a large class of correlators of interest are expressible in terms of expectation values of traces of words in a zero-dimensional gaussian complex matrix model. We develop a loop-equation based, analytic strategy for evaluating such expectation values to any order in the genus expansion. We reproduce the expectation values which were needed for the calculation of the one-loop, genus one correction to the anomalous dimension of BMN-operators and which were earlier obtained by combinatorial means. Furthermore, we present the expectation values needed for the calculation of the one-loop, genus two correction. (author)

Loop-space quantum formulation of free electromagnetism

International Nuclear Information System (INIS)

Di Bartolo, C.; Nori, F.; Gambini, R.; Trias, A.

1983-01-01

A procedure for direct quantization of free electromagnetism in the loop-space is proposed. Explicit solutions for the loop-dependent vacuum and the Wilson loop-average are given. It is shown that elementary lines of magnetic field appear as extremals in the vacuum state as a result of the regularization procedure

A totally diverting loop colostomy.

Science.gov (United States)

Merrett, N. D.; Gartell, P. C.

1993-01-01

A technique is described where the distal limb of a loop colostomy is tied with nylon or polydioxanone. This ensures total faecal diversion and dispenses with the supporting rod, enabling early application of stoma appliances. The technique does not interfere with the traditional transverse closure of a loop colostomy. PMID:8379632

Loop Quantum Cosmology.

Science.gov (United States)

Bojowald, Martin

2008-01-01

Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time. Supplementary material is available for this article at 10.12942/lrr-2008-4.

Hydraulic loop: practices using open control systems

International Nuclear Information System (INIS)

Carrasco, J.A.; Alonso, L.; Sanchez, F.

1998-01-01

The Tecnatom Hydraulic Loop is a dynamic training platform. It has been designed with the purpose of improving the work in teams. With this system, the student can obtain a full scope vision of a system. The hydraulic Loop is a part of the Tecnatom Maintenance Centre. The first objective of the hydraulic Loop is the instruction in components, process and process control using open control system. All the personal of an electric power plant can be trained in the Hydraulic Loop with specific courses. The development of a dynamic tool for tests previous to plant installations has been an additional objective of the Hydraulic Loop. The use of this platform is complementary to the use of full-scope simulators in order to debug and to analyse advanced control strategies. (Author)

Osmotic mechanism of the loop extrusion process

Science.gov (United States)

Yamamoto, Tetsuya; Schiessel, Helmut

2017-09-01

The loop extrusion theory assumes that protein factors, such as cohesin rings, act as molecular motors that extrude chromatin loops. However, recent single molecule experiments have shown that cohesin does not show motor activity. To predict the physical mechanism involved in loop extrusion, we here theoretically analyze the dynamics of cohesin rings on a loop, where a cohesin loader is in the middle and unloaders at the ends. Cohesin monomers bind to the loader rather frequently and cohesin dimers bind to this site only occasionally. Our theory predicts that a cohesin dimer extrudes loops by the osmotic pressure of cohesin monomers on the chromatin fiber between the two connected rings. With this mechanism, the frequency of the interactions between chromatin segments depends on the loading and unloading rates of dimers at the corresponding sites.

Two-Loop Scattering Amplitudes from the Riemann Sphere

CERN Document Server

Geyer, Yvonne; Monteiro, Ricardo; Tourkine, Piotr

2016-01-01

The scattering equations give striking formulae for massless scattering amplitudes at tree level and, as shown recently, at one loop. The progress at loop level was based on ambitwistor string theory, which naturally yields the scattering equations. We proposed that, for ambitwistor strings, the standard loop expansion in terms of the genus of the worldsheet is equivalent to an expansion in terms of nodes of a Riemann sphere, with the nodes carrying the loop momenta. In this paper, we show how to obtain two-loop scattering equations with the correct factorization properties. We adapt genus-two integrands from the ambitwistor string to the nodal Riemann sphere and show that these yield correct answers, by matching standard results for the four-point two-loop amplitudes of maximal supergravity and super-Yang-Mills theory. In the Yang-Mills case, this requires the loop analogue of the Parke-Taylor factor carrying the colour dependence, which includes non-planar contributions.

Quantum chromodynamics as dynamics of loops

International Nuclear Information System (INIS)

Makeenko, Yu.M.; Migdal, A.A.

1981-01-01

QCD is entirely reformulated in terms of white composite fields - the traces of the loop products. The 1/N expansion turns out to be the WKB (Hartree-Fock) approximation for these fields. The 'classical' equation describing the N = infinite case is reduced tp a bootstrap form. New, manifestly gauge-invariant perturbation theory in the loop space, reproducing asymptotic freedom, is developed by iterations of this equation. The area law appears to be a self-consistent solution at large loops. (orig.)

The Universal One-Loop Effective Action

CERN Document Server

Drozd, Aleksandra; Quevillon, Jérémie; You, Tevong

2016-01-01

We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.

The universal one-loop effective action

International Nuclear Information System (INIS)

Drozd, Aleksandra; Ellis, John; Quevillon, Jérémie; You, Tevong

2016-01-01

We present the universal one-loop effective action for all operators of dimension up to six obtained by integrating out massive, non-degenerate multiplets. Our general expression may be applied to loops of heavy fermions or bosons, and has been checked against partial results available in the literature. The broad applicability of this approach simplifies one-loop matching from an ultraviolet model to a lower-energy effective field theory (EFT), a procedure which is now reduced to the evaluation of a combination of matrices in our universal expression, without any loop integrals to evaluate. We illustrate the relationship of our results to the Standard Model (SM) EFT, using as an example the supersymmetric stop and sbottom squark Lagrangian and extracting from our universal expression the Wilson coefficients of dimension-six operators composed of SM fields.

Mathematical Modeling of Loop Heat Pipes

Science.gov (United States)

Kaya, Tarik; Ku, Jentung; Hoang, Triem T.; Cheung, Mark L.

1998-01-01

The primary focus of this study is to model steady-state performance of a Loop Heat Pipe (LHP). The mathematical model is based on the steady-state energy balance equations at each component of the LHP. The heat exchange between each LHP component and the surrounding is taken into account. Both convection and radiation environments are modeled. The loop operating temperature is calculated as a function of the applied power at a given loop condition. Experimental validation of the model is attempted by using two different LHP designs. The mathematical model is tested at different sink temperatures and at different elevations of the loop. Tbc comparison of the calculations and experimental results showed very good agreement (within 3%). This method proved to be a useful tool in studying steady-state LHP performance characteristics.

Loop expansion in massless three-dimensional QED

International Nuclear Information System (INIS)

Guendelman, E.I.; Radulovic, Z.M.

1983-01-01

It is shown how the loop expansion in massless three-dimensional QED can be made finite, up to three loops, by absorbing the infrared divergences in a gauge-fixing term. The same method removes leading and first subleading singularities to all orders of perturbation theory, and all singularities of the fermion self-energy to four loops

Tracking Positioning Algorithm for Direction of Arrival Based on Direction Lock Loop

Directory of Open Access Journals (Sweden)

Xiu-Zhi Cheng

2015-06-01

Full Text Available In order to solve the problem of poor real-time performance, low accuracy and high computational complexity in the traditional process of locating and tracking of Direction of Arrival (DOA of moving targets, this paper proposes a DOA algorithm based on the Direction Lock Loop (DILL which adopts Lock Loop structure to realize the estimation and location of DOA and can adjust the direction automatically along with the changes of a signal’s angular variation to track the position of the signal. Meanwhile, to reduce the influence of nonlinearity and noise on its performance, the UKF filter is designed for eliminating interference of the estimated target signal to improve accuracy of the signal tracking and stability of the system. Simulation results prove that the algorithm can not only get a high resolution DOA estimate signal, but can also locate and track multiple mobile targets effectively with enhanced accuracy, efficiency and stability.

Enhancing the effectiveness of human-robot teaming with a closed-loop system.

Science.gov (United States)

Teo, Grace; Reinerman-Jones, Lauren; Matthews, Gerald; Szalma, James; Jentsch, Florian; Hancock, Peter

2018-02-01

With technological developments in robotics and their increasing deployment, human-robot teams are set to be a mainstay in the future. To develop robots that possess teaming capabilities, such as being able to communicate implicitly, the present study implemented a closed-loop system. This system enabled the robot to provide adaptive aid without the need for explicit commands from the human teammate, through the use of multiple physiological workload measures. Such measures of workload vary in sensitivity and there is large inter-individual variability in physiological responses to imposed taskload. Workload models enacted via closed-loop system should accommodate such individual variability. The present research investigated the effects of the adaptive robot aid vs. imposed aid on performance and workload. Results showed that adaptive robot aid driven by an individualized workload model for physiological response resulted in greater improvements in performance compared to aid that was simply imposed by the system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Simple ML Detector for Multiple Antennas Communication System

Directory of Open Access Journals (Sweden)

Ahmad Taqwa

2010-10-01

Full Text Available In order to support providing broadband wireless communication services against limited and expensive frequency bandwidth, we have to develop a bandwidth efficient system. Therefore, in this paper we propose a closed-loop MIMO (Multiple-Input-Multiple-Output system using ML (Maximum Likelihood detector to optimize capacity and to increase system performance. What is especially exciting about the benefits offered by MIMO is that a high capacity and performance can be attained without additional frequency-spectral resource. The grand scenario of this concept is the attained advantages of transformation matrices having capability to allocate transmitted signals power suit to the channel. Furthermore, product of these matrices forms parallel singular channels. Due to zero inter-channels correlation, thus we can design ML detector to increase the system performance. Finally, computer simulations validates that at 0 dB SNR our system can reach optimal capacity up to 1 bps/Hz and SER up to 0.2 higher than opened-loop MIMO.

Construction of a single/multiple wavelength RZ optical pulse source at 40 GHz by use of wavelength conversion in a high-nonlinearity DSF-NOLM

DEFF Research Database (Denmark)

Yu, Jianjun; Yujun, Qian; Jeppesen, Palle

2001-01-01

A single or multiple wavelength RZ optical pulse source at 40 GHz is successfully obtained by using wavelength conversion in a nonlinear optical loop mirror consisting of high nonlinearity-dispersion shifted fiber.......A single or multiple wavelength RZ optical pulse source at 40 GHz is successfully obtained by using wavelength conversion in a nonlinear optical loop mirror consisting of high nonlinearity-dispersion shifted fiber....

A LabVIEW model incorporating an open-loop arterial impedance and a closed-loop circulatory system.

Science.gov (United States)

Cole, R T; Lucas, C L; Cascio, W E; Johnson, T A

2005-11-01

While numerous computer models exist for the circulatory system, many are limited in scope, contain unwanted features or incorporate complex components specific to unique experimental situations. Our purpose was to develop a basic, yet multifaceted, computer model of the left heart and systemic circulation in LabVIEW having universal appeal without sacrificing crucial physiologic features. The program we developed employs Windkessel-type impedance models in several open-loop configurations and a closed-loop model coupling a lumped impedance and ventricular pressure source. The open-loop impedance models demonstrate afterload effects on arbitrary aortic pressure/flow inputs. The closed-loop model catalogs the major circulatory waveforms with changes in afterload, preload, and left heart properties. Our model provides an avenue for expanding the use of the ventricular equations through closed-loop coupling that includes a basic coronary circuit. Tested values used for the afterload components and the effects of afterload parameter changes on various waveforms are consistent with published data. We conclude that this model offers the ability to alter several circulatory factors and digitally catalog the most salient features of the pressure/flow waveforms employing a user-friendly platform. These features make the model a useful instructional tool for students as well as a simple experimental tool for cardiovascular research.

Inbreeding and building up small populations of stingless bees (Hymenoptera, Apidae

Directory of Open Access Journals (Sweden)

Paulo Nogueira-Neto

2002-12-01

Full Text Available A study of the viability of small populations of Hymenoptera is a matter of importance to gain a better zoological, ethological, genetical and ecological knowledge of these insects, and for conservation purposes, mainly because of the consequences to the survival of colonies of many species of bees, wasps, and ants. Based on the Whiting (1943 principle, Kerr & Vencovski (1982 presented a hypothesis that states that viable populations of stingless bees (Meliponini should have at least 40 colonies to survive. This number was later extended to 44 colonies by Kerr (1985. This would be necessary to avoid any substantial amount of homozygosis in the pair of chromosomic sexual loci, by keeping at least six different sexual gene alleles in a reproductive population. In most cases this would prevent the production of useless diploid males. However, several facts weigh against considering this as a general rule. From 1990 to 2001, 287 colony divisions were made, starting with 28 foundation colonies, in the inbreeding and population experiments with the Meliponini reported here. These experiments constitute the most extensive and longest scientific research ever made with Meliponini bees. In ten different experiments presented here, seven species (one with two subspecies of Meliponini bees were inbred in five localities inside their wide-reaching native habitats, and in two localities far away from these habitats. This was done for several years. On the whole, the number of colonies increased and the loss of colonies over the years was small. In two of these experiments, although these populations were far (1,000 km and 1,200 km from their native habitat, their foundation colonies were multiplied successfuly. It was possible to build up seven strong and three expanding medium populations, starting with one, two, three or even five colonies. However, in six other cases examined here, the Whiting (1943 principle and the hypothesis of Kerr & Vencovski (1982

$H^\\infty$ control of systems with multiple I/O delays via decomposition to adobe problems

NARCIS (Netherlands)

Meinsma, Gjerrit; Mirkin, Leonid

In this paper, the standard (four-block) $H^\\infty$ control problem for systems with multiple input-output delays in the feedback loop is studied. The central idea is to see the multiple delay operator as a special series connection of elementary delay operators, called the adobe delay operators.

Mechanical evaluation of space closure loops in orthodontics.

Science.gov (United States)

Rodrigues, Eduardo Uggeri; Maruo, Hiroshi; Guariza Filho, Odilon; Tanaka, Orlando; Camargo, Elisa Souza

2011-01-01

This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS) and beta-titanium (BT) wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01) of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01). Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01). It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

Mechanical evaluation of space closure loops in Orthodontics

Directory of Open Access Journals (Sweden)

Eduardo Uggeri Rodrigues

2011-02-01

Full Text Available This study evaluated the mechanical performance of teardrop-shaped loops and teardrop-shaped loops with helix used in orthodontic space closure. Sixty retraction loops made with 0.019" x 0.025" stainless steel (SS and beta-titanium (BT wires were used. They were attached to a testing machine to measure the magnitudes of the sagittal force and the load-deflection ratio necessary for 1 mm, 2 mm and 3 mm activation. The results demonstrated that the BT alloy presented significantly smaller mean values (p < 0.01 of sagittal force and load-deflection than the SS alloy. The loop with the highest mean value of sagittal force and load-deflection was the teardrop-shaped loop (p < 0.01. Differences were observed in the mean values of sagittal force and load-deflection among activations, and the highest mean value was found in the activation of 3 mm, while the smallest mean value was evident in the activation of 1 mm (p < 0.01. It could be concluded that the metallic alloy used and the presence of a helix in configuration of the loops may have a strong influence on the sagittal force produced and on the load-deflection ratio; the teardrop-shaped loops and teardrop-shaped loops with helix in BT presented the release of lighter forces; the teardrop-shaped loop in SS generated a high load-deflection ratio, providing high magnitudes of horizontal force during its deactivation.

Protein Loop Structure Prediction Using Conformational Space Annealing.

Science.gov (United States)

Heo, Seungryong; Lee, Juyong; Joo, Keehyoung; Shin, Hang-Cheol; Lee, Jooyoung

2017-05-22

We have developed a protein loop structure prediction method by combining a new energy function, which we call E PLM (energy for protein loop modeling), with the conformational space annealing (CSA) global optimization algorithm. The energy function includes stereochemistry, dynamic fragment assembly, distance-scaled finite ideal gas reference (DFIRE), and generalized orientation- and distance-dependent terms. For the conformational search of loop structures, we used the CSA algorithm, which has been quite successful in dealing with various hard global optimization problems. We assessed the performance of E PLM with two widely used loop-decoy sets, Jacobson and RAPPER, and compared the results against the DFIRE potential. The accuracy of model selection from a pool of loop decoys as well as de novo loop modeling starting from randomly generated structures was examined separately. For the selection of a nativelike structure from a decoy set, E PLM was more accurate than DFIRE in the case of the Jacobson set and had similar accuracy in the case of the RAPPER set. In terms of sampling more nativelike loop structures, E PLM outperformed E DFIRE for both decoy sets. This new approach equipped with E PLM and CSA can serve as the state-of-the-art de novo loop modeling method.

Effect of Loop Diameter on the Steady State and Stability Behaviour of Single-Phase and Two-Phase Natural Circulation Loops

Directory of Open Access Journals (Sweden)

P. K. Vijayan

2008-01-01

Full Text Available In natural circulation loops, the driving force is usually low as it depends on the riser height which is generally of the order of a few meters. The heat transport capability of natural circulation loops (NCLs is directly proportional to the flow rate it can generate. With low driving force, the straightforward way to enhance the flow is to reduce the frictional losses. A simple way to do this is to increase the loop diameter which can be easily adopted in pressure tube designs such as the AHWR and the natural circulation boilers employed in fossil-fuelled power plants. Further, the loop diameter also plays an important role on the stability behavior. An extensive experimental and theoretical investigation of the effect of loop diameter on the steady state and stability behavior of single- and two-phase natural circulation loops have been carried out and the results of this study are presented in this paper.

UPTF loop seal tests and their RELAP simulation

International Nuclear Information System (INIS)

Tuomainen, M.; Tuunanen, J.

1997-01-01

In a pressurized water reactor the loop seals have an effect on the natural circulation. If a loop seal is filled with water it can cause a flow stagnation in the loop during two-phase natural circulation. Also the pressure loss over a filled loop seal is high, which lowers the water level in the core. Tests to investigate the loop seal behaviour were performed on a German Upper Plenum Test Facility (UPTF). The purpose of the tests was to study the amount of water in the loop seal under different steam flow rates. The tests were simulated with RELAP5/MOD3.2. With high steam flow rates the code had problems in simulating the amount of the water remaining in the pump elbow, but in general the agreement between the calculated results and the experimental data was good. (orig.)

SU(2) string tension from large Wilson loops

International Nuclear Information System (INIS)

Karsch, F.; Lang, C.B.

1984-01-01

We determine expectation values of Wilson loops and correlations of Polyakov loops on lattices of size 10 X 16 3 and 8 X 16 3 at β values 2.25 and 2.375. Utilizing a recently proposed method to reduce the variance of loop expectation values, we are able to measure loops up to 6 X 6. We find Λsub(L) = 0.0151 +- 0.0006√sub(K) at β = 2.375. (orig.)

Incremental Closed-loop Identification of Linear Parameter Varying Systems

DEFF Research Database (Denmark)

Bendtsen, Jan Dimon; Trangbæk, Klaus

2011-01-01

, closed-loop system identification is more difficult than open-loop identification. In this paper we prove that the so-called Hansen Scheme, a technique known from linear time-invariant systems theory for transforming closed-loop system identification problems into open-loop-like problems, can be extended...

Studying DNA looping by single-molecule FRET.

Science.gov (United States)

Le, Tung T; Kim, Harold D

2014-06-28

Bending of double-stranded DNA (dsDNA) is associated with many important biological processes such as DNA-protein recognition and DNA packaging into nucleosomes. Thermodynamics of dsDNA bending has been studied by a method called cyclization which relies on DNA ligase to covalently join short sticky ends of a dsDNA. However, ligation efficiency can be affected by many factors that are not related to dsDNA looping such as the DNA structure surrounding the joined sticky ends, and ligase can also affect the apparent looping rate through mechanisms such as nonspecific binding. Here, we show how to measure dsDNA looping kinetics without ligase by detecting transient DNA loop formation by FRET (Fluorescence Resonance Energy Transfer). dsDNA molecules are constructed using a simple PCR-based protocol with a FRET pair and a biotin linker. The looping probability density known as the J factor is extracted from the looping rate and the annealing rate between two disconnected sticky ends. By testing two dsDNAs with different intrinsic curvatures, we show that the J factor is sensitive to the intrinsic shape of the dsDNA.

Process/Equipment Co-Simulation on Syngas Chemical Looping Process

Energy Technology Data Exchange (ETDEWEB)

Zeng, Liang; Zhou, Qiang; Fan, Liang-Shih

2012-09-30

The chemical looping strategy for fossil energy applications promises to achieve an efficient energy conversion system for electricity, liquid fuels, hydrogen and/or chemicals generation, while economically separate CO{sub 2} by looping reaction design in the process. Chemical looping particle performance, looping reactor engineering, and process design and applications are the key drivers to the success of chemical looping process development. In order to better understand and further scale up the chemical looping process, issues such as cost, time, measurement, safety, and other uncertainties need to be examined. To address these uncertainties, advanced reaction/reactor modeling and process simulation are highly desired and the modeling efforts can accelerate the chemical looping technology development, reduce the pilot-scale facility design time and operating campaigns, as well as reduce the cost and technical risks. The purpose of this work is thus to conduct multiscale modeling and simulations on the key aspects of chemical looping technology, including particle reaction kinetics, reactor design and operation, and process synthesis and optimization.

Perception as a closed-loop convergence process.

Science.gov (United States)

Ahissar, Ehud; Assa, Eldad

2016-05-09

Perception of external objects involves sensory acquisition via the relevant sensory organs. A widely-accepted assumption is that the sensory organ is the first station in a serial chain of processing circuits leading to an internal circuit in which a percept emerges. This open-loop scheme, in which the interaction between the sensory organ and the environment is not affected by its concurrent downstream neuronal processing, is strongly challenged by behavioral and anatomical data. We present here a hypothesis in which the perception of external objects is a closed-loop dynamical process encompassing loops that integrate the organism and its environment and converging towards organism-environment steady-states. We discuss the consistency of closed-loop perception (CLP) with empirical data and show that it can be synthesized in a robotic setup. Testable predictions are proposed for empirical distinction between open and closed loop schemes of perception.

Feedback Loop Gains and Feedback Behavior (1996)

DEFF Research Database (Denmark)

Kampmann, Christian Erik

2012-01-01

Linking feedback loops and system behavior is part of the foundation of system dynamics, yet the lack of formal tools has so far prevented a systematic application of the concept, except for very simple systems. Having such tools at their disposal would be a great help to analysts in understanding...... large, complicated simulation models. The paper applies tools from graph theory formally linking individual feedback loop strengths to the system eigenvalues. The significance of a link or a loop gain and an eigenvalue can be expressed in the eigenvalue elasticity, i.e., the relative change...... of an eigenvalue resulting from a relative change in the gain. The elasticities of individual links and loops may be found through simple matrix operations on the linearized system. Even though the number of feedback loops can grow rapidly with system size, reaching astronomical proportions even for modest systems...

Two-Loop Splitting Amplitudes

International Nuclear Information System (INIS)

Bern, Z.

2004-01-01

Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes

Two-loop splitting amplitudes

International Nuclear Information System (INIS)

Bern, Z.; Dixon, L.J.; Kosower, D.A.

2004-01-01

Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes

Results from GRACE/SUSY at one-loop

International Nuclear Information System (INIS)

Fujimoto, J.; Ishikawa, T.; Kurihara, Y.; Jimbo, M.; Yasui, Y.; Kaneko, T.; Kon, T.; Kuroda, M.; Shimizu, Y.

2007-01-01

We report the recent development on the SUSY calculations with the help of GRACE system. GRACE/SUSY/1LOOP is the computer code which can generate Feynman diagrams in the MSSM automatically and compute one-loop amplitudes in the numerical way. We present new results of various two-body widths and chargino pair production at ILC (international linear collider) at one-loop level. (author)

LMFBR with booster pump in pumping loop

International Nuclear Information System (INIS)

Rubinstein, H.J.

1975-01-01

A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation

Computational advantages of reverberating loops for sensorimotor learning.

Science.gov (United States)

Fortney, Kristen; Tweed, Douglas B

2012-03-01

When we learn something new, our brain may store the information in synapses or in reverberating loops of electrical activity, but current theories of motor learning focus almost entirely on the synapses. Here we show that loops could also play a role and would bring advantages: loop-based algorithms can learn complex control tasks faster, with exponentially fewer neurons, and avoid the problem of weight transport. They do all this at a cost: in the presence of long feedback delays, loop algorithms cannot control very fast movements, but in this case, loop and synaptic mechanisms can complement each other-mixed systems quickly learn to make accurate but not very fast motions and then gradually speed up. Loop algorithms explain aspects of consolidation, the role of attention, and the relapses that are sometimes seen after a task has apparently been learned, and they make further predictions.

Innovative hybrid pile oscillator technique in the Minerve reactor: open loop vs. closed loop

Science.gov (United States)

Geslot, Benoit; Gruel, Adrien; Bréaud, Stéphane; Leconte, Pierre; Blaise, Patrick

2018-01-01

Pile oscillator techniques are powerful methods to measure small reactivity worth of isotopes of interest for nuclear data improvement. This kind of experiments has long been implemented in the Mineve experimental reactor, operated by CEA Cadarache. A hybrid technique, mixing reactivity worth estimation and measurement of small changes around test samples is presented here. It was made possible after the development of high sensitivity miniature fission chambers introduced next to the irradiation channel. A test campaign, called MAESTRO-SL, took place in 2015. Its objective was to assess the feasibility of the hybrid method and investigate the possibility to separate mixed neutron effects, such as fission/capture or scattering/capture. Experimental results are presented and discussed in this paper, which focus on comparing two measurements setups, one using a power control system (closed loop) and another one where the power is free to drift (open loop). First, it is demonstrated that open loop is equivalent to closed loop. Uncertainty management and methods reproducibility are discussed. Second, results show that measuring the flux depression around oscillated samples provides valuable information regarding partial neutron cross sections. The technique is found to be very sensitive to the capture cross section at the expense of scattering, making it very useful to measure small capture effects of highly scattering samples.

Thermal instabilities in magnetically confined plasmas: Solar coronal loops

International Nuclear Information System (INIS)

Habbal, S.R.; Rosner, R.

1979-01-01

The thermal stability of confined solar coronal structures (''loops'') is investigated, following both normal mode and a new, global instability analysis. We demonstrate that: (a) normal mode analysis shows modes with size scales comparable to that of loops to be unstable, but to be strongly affected by the loop boundary conditions; (b) a global analysis, based upon variation of the total loop energy losses and gains, yields loop stability conditions for global modes dependent upon the coronal loop heating process, with magnetically coupled heating processes giving marginal stability. The connection between the present analysis and the minimum flux corona of Hearn is also discussed

Feedback loop compensates for rectifier nonlinearity

Science.gov (United States)

1966-01-01

Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

Observing string breaking with Wilson loops

CERN Document Server

Kratochvila, S; Kratochvila, Slavo; Forcrand, Philippe de

2003-01-01

An uncontroversial observation of adjoint string breaking is proposed, while measuring the static potential from Wilson loops only. The overlap of the Wilson loop with the broken-string state is small, but non-vanishing, so that the broken-string groundstate can be seen if the Wilson loop is long enough. We demonstrate this in the context of the (2+1)d SU(2) adjoint static potential, using an improved version of the Luscher-Weisz exponential variance reduction. To complete the picture we perform the more usual multichannel analysis with two basis states, the unbroken-string state and the broken-string state (two so-called gluelumps). As by-products, we obtain the temperature-dependent static potential measured from Polyakov loop correlations, and the fundamental SU(2) static potential with improved accuracy. Comparing the latter with the adjoint potential, we see clear deviations from Casimir scaling.

Near BPS Wilson loop in β-deformed theories