14,270 research outputs found

    Average features of the muon component of EAS or = 10(17) eV

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    Three 10 sq m liquid scintillators were situated at approximately 0 m, 150 m and 250 m from the center of the Haverah Park array. The detectors were shielded by lead/barytes giving muon detection thresholds of 317 MeV, 431 MeV and 488 MeV respectively. During part of the operational period the 431 MeV threshold was lowered to 313 MeV for comparison purposes. For risetime measurement fast phototubes were used and the 10% to 70% amplitude time interval was parameterized by T sub 70. A muon lateral density distribution of the form rho mu (R theta) = krho(500)0.94 1/R(1 + R/490)-eta has been fitted to the data for 120 m R 600 m and 0.27 (500) 2.55. The shower size parameter (500) is the water Cerenkov response at 500 m from the core of the extensive air showers (EAS) and is relatable to the primary energy. The results show general consistency

    Muon fluctuation studies of EAS 10(17) eV

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    Fluctuation studies need to compare a parameter which is sensitive to longitudinal fluctuations against a parameter which is insensitive. Cascade calculations indicate that the shower size parameter at Haverah Park, rho (500), and the muon density are insensitive while parameters that significantly reflect the longitudinal development of a particular extensive air shower (EAS) include the muon/water Cerenkov response ratio and the muon arrival time dispersion. This paper presents conclusions based on muon fluctuation studies of EAS measured between 1976 and 1981 at Haverah Park

    The muon content of EAS as a function of primary energy

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    The muon content of extensive air showers (EAS) was measured over the wide primary energy range 10 to the 16th power to 10 to the 20th power eV. It is reported that the relative muon content of EAS decreases smoothly over the energy range 10 to the 17th power to 10 to the 19th power eV and concluded that the primary cosmic ray flux has a constant mass composition over this range. It is also reported that an apparent significant change in the power index occurs below 10 to the 17th power eV rho sub c (250 m) sup 0.78. Such a change indicates a significant change in primary mass composition in this range. The earlier conclusions concerning EAS of energy 10 to the 17th power eV are confirmed. Analysis of data in the 10 to the 16th power - 10 to the 17th power eV range revealed a previously overlooked selection bias in the data set. The full analysis of the complete data set in the energy range 10 to the 16th power - 10 to the 17th power ev with the selection bias eliminated is presented

    Finite element analysis applied to redesign of submerged entry nozzles for steelmaking

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    The production of steel by continuous casting is facilitated by the use of refractory hollow-ware components. A critical component in this process is the submerged entry nozzle (SEN). The normal operating conditions of the SEN are arduous, involving large temperature gradients and exposure to mechanical forces arising from the flow of molten steel; experimental development of the components is challenging in so hazardous an environment. The effects of the thermal stress conditions in relation to a well-tried design were therefore simulated using a finite element analysis approach. It was concluded from analyses that failures of the type being experienced are caused by the large temperature gradient within the nozzle. The analyses pointed towards a supported shoulder area of the nozzle being most vulnerable to failure and practical in-service experience confirmed this. As a direct consequence of the investigation, design modifications, incorporating changes to both the internal geometry and to the nature of the intermediate support material, were implemented, thereby substantially reducing the stresses within the Al2O3/graphite ceramic liner. Industrial trials of this modified design established that the component reliability would be significantly improved and the design has now been implemented in series production

    Manifestations of quantum holonomy in interferometry

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    Abelian and non-Abelian geometric phases, known as quantum holonomies, have attracted considerable attention in the past. Here, we show that it is possible to associate nonequivalent holonomies to discrete sequences of subspaces in a Hilbert space. We consider two such holonomies that arise naturally in interferometer settings. For sequences approximating smooth paths in the base (Grassmann) manifold, these holonomies both approach the standard holonomy. In the one-dimensional case the two types of holonomies are Abelian and coincide with Pancharatnam's geometric phase factor. The theory is illustrated with a model example of projective measurements involving angular momentum coherent states.Comment: Some changes, journal reference adde

    Metabolic Depression in Cunner (Tautogolabrus adspersus) Is Influenced by Ontogeny, and Enhances Thermal Tolerance

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    To examine the effect of ontogeny on metabolic depression in the cunner (Tautogolabrus adspersus), and to understand how ontogeny and the ability to metabolically depress influence this species' upper thermal tolerance: 1) the metabolic rate of 9°C-acclimated cunner of three size classes [0.2–0.5 g, young of the year (YOY); 3–6 g, small; and 80–120 g, large (adult)] was measured during a 2°C per day decrease in temperature; and 2) the metabolic response of the same three size classes of cunner to an acute thermal challenge [2°C h−1 from 10°C until Critical Thermal Maximum, CTMax] was examined, and compared to that of the Atlantic cod (Gadus morhua). The onset-temperature for metabolic depression in cunner increased with body size, i.e. from 5°C in YOY cunner to 7°C in adults. In contrast, the extent of metabolic depression was ∼80% (Q10 = ∼15) for YOY fish, ∼65% (Q10 = ∼8) for small fish and ∼55% (Q10 = ∼5) for adults, and this resulted in the metabolic scaling exponent (b) gradually increasing from 0.84 to 0.92 between 9°C to 1°C. All size classes of cunner had significantly (approximately 60%) lower routine metabolic rates at 10°C than Atlantic cod. However, there was no species' difference in the temperature-induced maximum metabolic rate, and this resulted in factorial metabolic scope values that were more than two-fold greater for cunner, and CTMax values that were 6–9°C higher (∼21 vs. 28°C). These results: 1) show that ontogeny influences the temperature of initiation and the extent of metabolic depression in cunner, but not O2 consumption when in a hypometabolic state; and 2) suggest that the evolution of cold-induced metabolic depression in this northern wrasse species has not resulted in a trade-off with upper thermal tolerance, but instead, an enhancement of this species' metabolic plasticity

    Additional three-dimensional boundary-layer computations for a finite swept wing

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    Calculations have been made of the three-dimensional, compressible, turbulent boundary layer on the finite supercritical wing of the NASA modified F-8 transonic research airplane. The calculations were based on the wing pressure distribution measured in flight at M = 0.90, instead of on wind tunnel data at M = 0.50 and 0.99. Data on the boundary-layer thickness, displacement thickness, skin-friction components, and integrated streamwise skin friction are presented for points along the streamwise stations at which pressure measurements were made

    National Register of Historic Places Eligibility Testing of Site 41SM385 Within TxDOT\u27s Tyler District, Smith County, Texas

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    PBS&J, an Atkins company, was contracted by the North East Texas Regional Mobility Authority to conduct National Register of Historic Places eligibility testing of site 41SM385, a prehistoric campsite on a small rise above the floodplain of Indian Creek in western Smith County, Texas. Testing investigations were conducted during March and September 2009. The site was subjected to a systematic program of shovel testing, mechanical trenching, and hand excavation in an effort to identify cultural features or living surfaces and optimize recovery of diagnostic faunal, floral, and artifactual remains. The recovered cultural artifacts indicate that site 41SM385 represents a probable Woodland and Caddo‐aged occupation on a small rise on the creek floodplain. The Woodland component is based on recovered small Gary and Kent projectile points characteristic of Woodland culture of the region. The Caddo component is based on ceramic sherds of probable Early or Middle Caddo origin identified at the site. Radiocarbon dating of four ceramic sherds supports these assessments with three sherds dating to the Early to Middle Caddo periods and one sherd dating to the Woodland period. The lack of identified cultural features suggests that the Woodland component probably represents a series of ephemeral usages of the location, probably as short‐term campsites. The Caddo‐aged artifacts at the site probably represent a series of ephemeral usage of the location, either as a resource procurement locus ancillary to nearby site 41SM404 or as a short‐term campsite. The testing program failed to locate living surfaces or cultural features containing in situ artifactual or organic remains preserved on the site. The absence of cultural features and the paucity of lithic tools or ceramic remains make more‐meaningful functional interpretation infeasible. For this reason, the site lacks the data resources that would warrant National Register of Historic Places isting or designation as a State Archeological Landmark. No further work is recommended

    Detoxification enzyme activities (CYP1A1 and GST) in the skin of humpback whales as a function of organochlorine burdens and migration status

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    The activities of glutathione-s-transferase (GST) and cytochrome P-450 1A1 (CYP1A1) enzymes were measured in freshly extracted epidermis of live-biopsied, migrating, southern hemisphere humpback whales (Megaptera novaeangliae). The two quantified enzyme activities did not correlate strongly with each other. Similarly, neither correlated strongly with any of the organochlorine compound groups previously measured in the superficial blubber of the sample biopsy core, likely reflecting the anticipated low levels of typical aryl-hydrocarbon receptor ligands. GST activity did not differ significantly between genders or between northward (early migration) or southward (late migration) migrating cohorts. Indeed, the inter-individual variability in GST measurements was relatively low. This observation raises the possibility that measured activities were basal activities and that GST function was inherently impacted by the fasting state of the sampled animals, as seen in other species. These results do not support the implementation of CYP1A1 or GST as effective biomarkers of organochlorine contaminant burdens in southern hemisphere populations of humpback whales as advocated for other cetacean species. Further investigation of GST activity in feeding versus fasting cohorts may, however, provide some insight into the fasting metabolism of these behaviourally adapted populations. © 2014