3,592 research outputs found

    Efficient Symmetry Reduction and the Use of State Symmetries for Symbolic Model Checking

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    One technique to reduce the state-space explosion problem in temporal logic model checking is symmetry reduction. The combination of symmetry reduction and symbolic model checking by using BDDs suffered a long time from the prohibitively large BDD for the orbit relation. Dynamic symmetry reduction calculates representatives of equivalence classes of states dynamically and thus avoids the construction of the orbit relation. In this paper, we present a new efficient model checking algorithm based on dynamic symmetry reduction. Our experiments show that the algorithm is very fast and allows the verification of larger systems. We additionally implemented the use of state symmetries for symbolic symmetry reduction. To our knowledge we are the first who investigated state symmetries in combination with BDD based symbolic model checking

    Spraying as an Essential Part of Profitable Apple Orcharding

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    It was therefore planned from the start not merely to demonstrate the possibility of controlling apple insects and diseases but also to determine whether they could be controlled profitably. To accomplish this it was necessary to know: exactly what it cost to spray, what sprayed fruit yielded, and what it was worth in comparison with unsprayed fruit from the same orchards. In every spraying demonstration the time spent in mixing and applying the materials and the quantity of material used were recorded. The cost of labor of men and teams per hour was taken at the orchard owners\u27 estimates and the cost of materials was charged at the prices actually paid by the orchardists. In every orchard a block was set apart for the demonstration spraying, and another block, in every way comparable with the first, was left without spraying as a check on the results of spraying. The exact yields of both marketable and unmarketable fruit from the sprayed and from the unsprayed blocks, or from considerable parts of them, were noted. The net value of the fruit was determined by deducting from the actual prices received by the owners the estimated cost of picking, grading, packing, hauling, etc. The net value, therefore, was what the fruit was worth on the trees

    Cryptic choice of conspecific sperm controlled by the impact of ovarian fluid on sperm swimming behavior

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    Despite evidence that variation in male–female reproductive compatibility exists in many fertilization systems, identifying mechanisms of cryptic female choice at the gamete level has been a challenge. Here, under risks of genetic incompatibility through hybridization, we show how salmon and trout eggs promote fertilization by conspecific sperm. Using in vitro fertilization experiments that replicate the gametic microenvironment, we find complete interfertility between both species. However, if either species’ ova were presented with equivalent numbers of both sperm types, conspecific sperm gained fertilization precedence. Surprisingly, the species’ identity of the eggs did not explain this cryptic female choice, which instead was primarily controlled by conspecific ovarian fluid, a semiviscous, protein-rich solution that bathes the eggs and is released at spawning. Video analyses revealed that ovarian fluid doubled sperm motile life span and straightened swimming trajectory, behaviors allowing chemoattraction up a concentration gradient. To confirm chemoattraction, cell migration tests through membranes containing pores that approximated to the egg micropyle showed that conspecific ovarian fluid attracted many more spermatozoa through the membrane, compared with heterospecific fluid or water. These combined findings together identify how cryptic female choice can evolve at the gamete level and promote reproductive isolation, mediated by a specific chemoattractive influence of ovarian fluid on sperm swimming behavior

    Gate fidelity fluctuations and quantum process invariants

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    We characterize the quantum gate fidelity in a state-independent manner by giving an explicit expression for its variance. The method we provide can be extended to calculate all higher order moments of the gate fidelity. Using these results we obtain a simple expression for the variance of a single qubit system and deduce the asymptotic behavior for large-dimensional quantum systems. Applications of these results to quantum chaos and randomized benchmarking are discussed.Comment: 13 pages, no figures, published versio

    Snow metamorphism: a fractal approach

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    Snow is a porous disordered medium consisting of air and three water phases: ice, vapour and liquid. The ice phase consists of an assemblage of grains, ice matrix, initially arranged over a random load bearing skeleton. The quantitative relationship between density and morphological characteristics of different snow microstructures is still an open issue. In this work, a three-dimensional fractal description of density corresponding to different snow microstructure is put forward. First, snow density is simulated in terms of a generalized Menger sponge model. Then, a fully three-dimensional compact stochastic fractal model is adopted. The latter approach yields a quantitative map of the randomness of the snow texture, which is described as a three-dimensional fractional Brownian field with the Hurst exponent H varying as continuous parameter. The Hurst exponent is found to be strongly dependent on snow morphology and density. The approach might be applied to all those cases where the morphological evolution of snow cover or ice sheets should be conveniently described at a quantitative level

    Pathways to social well-being of children with intellectual disability: testing the Family Investment Model

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    BACKGROUND: Social well-being, including prosocial and peer relationship skills, independence and co-operation, is a particularly important developmental outcome in intellectual disability (ID). The present study investigated pathways to social well-being through the early years' family environment, particularly the role of parental investments in mediating the path from family poverty to child social well-being. METHODS: In line with the Family Investment Model (FIM), we tested whether parental investments between 3 and 5 years of age mediate the impact of family poverty at 9 months of age on children's social well-being at 7 years. Structural equation models were fitted to data from 555 children with ID identified from a UK population-based cohort. RESULTS: Findings indicated that home learning investments and the structural home environment (though not play) significantly mediated the effect of family poverty on children's social skills, albeit in different directions. While all parental investments reduced in the presence of poverty, the home learning environment appeared to promote social well-being, whereas the structural home environment did not. Sensitivity analyses controlling for co-occurring autism confirmed the pattern of findings. Child gender, ethnicity and parental educational qualifications did not moderate the mediational relationships, suggesting that FIM pathways to social well-being were relevant to all families. CONCLUSIONS: The FIM provides a helpful framework to map developmental pathways for children with an ID. Parental investments related to home learning, the structural home environment and play are reduced in the presence of poverty although their impact on child social well-being appears to differ

    The mental health and well-being of adolescents with/without intellectual disability in the UK

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    Aims To estimate the self-reported and parent-reported mental well-being of adolescents (aged 14 and 17) with/without intellectual disability in a sample of young people representative of the UK population. Methods Secondary analysis of data collected in Waves 6 and 7 of the UK's Millennium Cohort Study. The analytic sample consisted of 10,838 adolescent respondents at age 14 (361 with intellectual disability and 10,477 without) and 9,408 adolescent respondents at age 17 (292 with intellectual disability and 9,116 without). Results Parental reports of adolescent problems on the Strengths and Difficulties Questionnaire (SDQ) indicated that adolescents with intellectual disability at ages 14 and 17 were more likely to have problems than those without intellectual disability across all SDQ domains. Adolescent self-report data at age 17 indicated that adolescents with intellectual disability were more likely to (self)-report that they had problems than those without intellectual disability on all but one SDQ domain. The magnitude of relative inequality between those with and without intellectual disability was consistently lower for self-report than parental report. On indicators of depression, mental well-being, self-harm, positive mental health, happiness and general psychological distress at ages 14 and 17, we found no self-reported group differences between adolescents with and without intellectual disability. Conclusions Further research is needed to understand: (1) why the magnitude of mental health inequalities between those with and without intellectual disability on the SDQ may be dependent on the identity of the informant; and (2) whether such differences are also apparent for other measures of mental health or well-being

    Pax3 synergizes with Gli2 and Zic1 in transactivating the Myf5 epaxial somite enhancer

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    AbstractBoth Glis, the downstream effectors of hedgehog signaling, and Zic transcription factors are required for Myf5 expression in the epaxial somite. Here we demonstrate a novel synergistic interaction between members of both families and Pax3, a paired-domain transcription factor that is essential for both myogenesis and neural crest development. We show that Pax3 synergizes with both Gli2 and Zic1 in transactivating the Myf5 epaxial somite (ES) enhancer in concert with the Myf5 promoter. This synergy is dependent on conserved functional domains of the proteins, as well as on a novel homeodomain motif in the Myf5 promoter and the essential Gli motif in the ES enhancer. Importantly, overexpression of Zic1 and Pax3 in the 10T1/2 mesodermal cell model results in enrichment of these factors at the endogenous Myf5 locus and induction of Myf5 expression. In our previous work, we showed that by enhancing nuclear translocation of Gli factors, Zics provide spatiotemporal patterning for Gli family members in the epaxial induction of Myf5 expression. Our current study indicates a complementary mechanism in which association with DNA-bound Pax3 strengthens the ability of both Zic1 and Gli2 to transactivate Myf5 in the epaxial somite
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