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New Concepts in Fish Ladder Design, Volume III of IV, Assessment of Fishway Development and Design, 1982-1983 Final Report.  

Energy Technology Data Exchange (ETDEWEB)

This volume covers the broad, though relatively short, historical basis for this project. The historical developments of certain design features, criteria and research activities are traced. Current design practices are summarized based on the results of an international survey and interviews with agency personnel and consultants. The fluid mechanics and hydraulics of fishway systems are discussed. Fishways (or fishpasses) can be classified in two ways: (1) on the basis of the method of water control (chutes, steps (ladders), or slots); and (2) on the basis of the degree and type of water control. This degree of control ranges from a natural waterfall to a totally artificial environment at a hatchery. Systematic procedures for analyzing fishways based on their configuration, species, and hydraulics are presented. Discussions of fish capabilities, energy expenditure, attraction flow, stress and other factors are included.

Powers, Patrick D.; Orsborn, John F.

1985-08-01

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Selectivity of fish ladders: a bottleneck in Neotropical fish movement  

Directory of Open Access Journals (Sweden)

Full Text Available Although dozens of fish ladders have been constructed at dams of Brazilian reservoirs, there are few studies evaluating their efficiency as a tool for the conservation of Neotropical ichthyofauna, especially for migratory species. Therefore, the present study evaluated the selectivity of the species that entered and ascended the fish ladder located next to Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power Plant on the Tocantins River. Samples were taken monthly from November, 2002 through October, 2003, in the resting pools of the ladder, using cast nets, and in the downstream stretch, using gillnets. The selectivity of the ladder in attracting fish was evaluated by comparing the occurrence, relative abundance, dominance and the congruence of abundance ranks of migratory and non-migratory species in the ladder and in the stretch of river immediately downstream. Species richness and fish abundance in the resting pools were used to evaluate selectivity along the ladder. The effects on selectivity by temporal variations in water level downriver and maximum flow velocity in the fish ladder were also analyzed. Out of the 130 species recorded downriver, 62.3% were caught in the ladder, and migratory species were clearly favored. However, more than 2/3 of the catch belonged to only three species (Rhaphiodon vulpinus, Psectrogaster amazonica and Oxydoras niger. Although the majority of the species that entered the ladder were able to reach its top, there was a sharp reduction in abundance of individuals towards the top. Temporal variations in the water level below the dam influenced richness and abundance of fish concentrated downstream and in the ladder, with lower values during periods of low water. In the ladder, a maximum flow velocity of 2.3 m/s, although also selective, proved to be more appropriate for fish ascension than a velocity of 2.8 m/s. It was concluded that the entry and ascension of the fish in the ladder were not congruent with their proportions in the downriver stretch: fish samples in the ladder were clearly dominated by a few species, including some that do not need to be translocated. Thus, selectivity constitutes an important bottleneck to initiatives for translocating fish aimed at conserving their stocks or biodiversity. It is urgent to review the decision-making process for the construction of fish passages and to evaluate the functioning of those already operating.Dezenas de escadas de peixes foram construídas em barragens de reservatórios brasileiros, mas são raros os estudos acerca de suas eficiências como instrumentos de conservação da ictiofauna Neotropical, em especial de espécies migradoras. Neste contexto, o presente estudo teve como objetivo avaliar a seletividade específica no ingresso e ascensão de peixes na escada localizada junto à barragem de Lajeado (UHE Luis Eduardo Magalhães, rio Tocantins. Amostragens foram realizadas mensalmente de novembro de 2002 a outubro de 2003 nos tanques de descanso da escada, utilizando tarrafas, e no trecho a jusante, utilizando redes de espera. A avaliação da seletividade no ingresso da escada foi realizada através da comparação da ocorrência, abundância relativa, dominância e congruência dos ranks de abundância de espécies migradoras e não migradoras na escada e no trecho imediatamente a jusante. A riqueza e abundância específica nos diferentes tanques de descanso foram utilizadas para avaliar a seletividade ao longo da escada. Os efeitos das variações temporais do nível hidrométrico de jusante e da velocidade de fluxo na seletividade foram também analisados. Das 130 espécies registradas a jusante, 63,2% foram capturadas na escada, com claro favorecimento das espécies migradoras. Entretanto, mais de 2/3 das capturas pertenceram a apenas três espécies (Rhaphiodon vulpinus, Psectrogaster amazonica e Oxydoras niger. Embora a maioria das espécies que ingressa na escada possa alcançar seu topo, constatou-se uma redução pronunciada na abundância. Variações temporais no nível da água a jusante d

Carlos Sérgio Agostinho

2007-01-01

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Fish ladders: safe fish passage or hotspot for predation?  

Directory of Open Access Journals (Sweden)

Full Text Available Fish ladders are a strategy for conserving biodiversity, as they can provide connectivity between fragmented habitats and reduce predation on shoals that accumulate immediately below dams. Although the impact of predation downstream of reservoirs has been investigated, especially in juvenile salmonids during their downstream movements, nothing is known about predation on Neotropical fish in the attraction and containment areas commonly found in translocation facilities. This study analysed predation in a fish passage system at the Lajeado Dam on the Tocantins River in Brazil. The abundance, distribution, and the permanence (time spent of large predatory fish along the ladder, the injuries imposed by piranhas during passage and the presence of other vertebrate predators were investigated. From December 2002 to October 2003, sampling was conducted in four regions (downstream, along the ladder, in the forebay, and upstream of the reservoir using gillnets, cast nets and counts or visual observations. The captured fish were tagged with thread and beads, and any mutilations were registered. Fish, birds and dolphins were the main predator groups observed, with a predominance of the first two groups. The entrance to the ladder, in the downstream region, was the area with the highest number of large predators and was the only region with relevant non-fish vertebrates. The main predatory fish species were Rhaphiodon vulpinus, Hydrolycus armatus, and Serrasalmus rhombeus. Tagged individuals were detected predating along the ladder for up to 90 days. Mutilations caused by Serrasalmus attacks were noted in 36% of species and 4% of individuals at the top of the ladder. Our results suggested that the high density of fish in the restricted ladder environment, which is associated with injuries suffered along the ladder course and the presence of multiple predator groups with different predation strategies, transformed the fish corridor into a hotspot for predation.Passagens para peixes têm sido consideradas como estratégias para conservação da biodiversidade, visando além de assegurar os deslocamentos entre habitats fragmentados, atenuar a mortalidade por predação dos estratos populacionais que se concentram nos trechos imediatamente abaixo de barragens. Embora a mortalidade por predação no trecho a jusante de reservatórios tenha sido bem investigada, especialmente sobre os juvenis de salmonídeos em movimentos descendentes, nada se sabe acerca da predação de peixes neotropicais em áreas de atração e confinamento de peixes, eventos comuns a essas facilidades de transposição. Nesse estudo são analisados aspectos da predaç??o em um sistema de transposição de peixes (barragem de Lajeado, rio Tocantins, Brasil, buscando avaliar a abundância, a distribuição e o tempo de permanência de grandes peixes predadores na escada, as injúrias impostas por piranhas durante a passagem e a ocorrência de outros vertebrados predadores. Para isso foram realizadas amostragens a jusante, ao longo da escada, no trecho imediatamente acima da barragem e a montante do reservatório, utilizando redes de espera, tarrafas e contagens ou registros visuais durante o período de um ano (Novembro de 2002 a Outubro de 2003. Marcações com linha e missanga e registro de mutilações foram também realizados em concomitância. Peixes, aves, quelônios e cetáceos foram os principais grupos de predadores observados, com predomínio dos dois primeiros. A área nas imediações da entrada da escada, a jusante, foi a região com maior número de grandes predadores, sendo a única de relevância para vertebrados não peixes. Indivíduos marcados permaneceram na escada exercendo a piscivoria por até 90 dias. Rhaphiodon vulpinus, Hydrolycus armatus e Serrasalmus rhombeus foram os principais peixes predadores. Mutilações por ataques de Serrasalmus atingiram 36% das espécies e alcançaram 4% dos indivíduos no topo da escada. Os resultados sugerem que a alta densidade de peixes no ambiente restrito da escada, associada às inj

Angelo Antonio Agostinho

2012-10-01

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New Concepts in Fish Ladder Design, Part I of IV, Summary Report, 1982-1984 Final Project Report.  

Energy Technology Data Exchange (ETDEWEB)

The report looks at the most active periods of fishway research since 1938 as background for a project to apply fundamental fluid and bio-mechanics to fishway design, and develop more cost effective fish passage facilities with primary application to small scale hydropower facilities. Also discussed are new concepts in fishway design, an assessment of fishway development and design, and an analysis of barriers to upstream migration. (ACR)

Orsborn, John F.

1985-08-01

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Selectivity of fish ladders: a bottleneck in Neotropical fish movement  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Dezenas de escadas de peixes foram construídas em barragens de reservatórios brasileiros, mas são raros os estudos acerca de suas eficiências como instrumentos de conservação da ictiofauna Neotropical, em especial de espécies migradoras. Neste contexto, o presente estudo teve como objetivo avaliar a [...] seletividade específica no ingresso e ascensão de peixes na escada localizada junto à barragem de Lajeado (UHE Luis Eduardo Magalhães, rio Tocantins). Amostragens foram realizadas mensalmente de novembro de 2002 a outubro de 2003 nos tanques de descanso da escada, utilizando tarrafas, e no trecho a jusante, utilizando redes de espera. A avaliação da seletividade no ingresso da escada foi realizada através da comparação da ocorrência, abundância relativa, dominância e congruência dos ranks de abundância de espécies migradoras e não migradoras na escada e no trecho imediatamente a jusante. A riqueza e abundância específica nos diferentes tanques de descanso foram utilizadas para avaliar a seletividade ao longo da escada. Os efeitos das variações temporais do nível hidrométrico de jusante e da velocidade de fluxo na seletividade foram também analisados. Das 130 espécies registradas a jusante, 63,2% foram capturadas na escada, com claro favorecimento das espécies migradoras. Entretanto, mais de 2/3 das capturas pertenceram a apenas três espécies (Rhaphiodon vulpinus, Psectrogaster amazonica e Oxydoras niger). Embora a maioria das espécies que ingressa na escada possa alcançar seu topo, constatou-se uma redução pronunciada na abundância. Variações temporais no nível da água a jusante da barragem influenciaram a riqueza e a abundância de peixes que se concentram na entrada e dentro da escada, com redução nos valores durante períodos de níveis baixos. Já na escada, a velocidade de fluxo de 2,3 m.s-1, embora também seletiva, mostrou-se mais adequada à ascensão de peixes em relação a de 2,8 m.s-1. Conclui-se, portanto, que o ingresso e a ascensão de peixes na escada não são congruentes com a composição e relações de abundância das espécies no trecho a jusante. O conjunto de espécies que efetivamente ascende a escada é dominado por poucas espécies, podendo incluir entre as dominantes aquelas que não necessitam ser transpostas. Dessa maneira, a seletividade se constitui num importante gargalo nas iniciativas de transposição de peixes visando a conservação dos estoques ou da biodiversidade, sendo urgente a revisão do processo decisório sobre a construção destes dispositivos e a avaliação acerca do funcionamento daquelas já construídas. Abstract in english Although dozens of fish ladders have been constructed at dams of Brazilian reservoirs, there are few studies evaluating their efficiency as a tool for the conservation of Neotropical ichthyofauna, especially for migratory species. Therefore, the present study evaluated the selectivity of the species [...] that entered and ascended the fish ladder located next to Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power Plant) on the Tocantins River. Samples were taken monthly from November, 2002 through October, 2003, in the resting pools of the ladder, using cast nets, and in the downstream stretch, using gillnets. The selectivity of the ladder in attracting fish was evaluated by comparing the occurrence, relative abundance, dominance and the congruence of abundance ranks of migratory and non-migratory species in the ladder and in the stretch of river immediately downstream. Species richness and fish abundance in the resting pools were used to evaluate selectivity along the ladder. The effects on selectivity by temporal variations in water level downriver and maximum flow velocity in the fish ladder were also analyzed. Out of the 130 species recorded downriver, 62.3% were caught in the ladder, and migratory species were clearly favored. However, more than 2/3 of the catch belonged to only three species (Rhaphiodon vulpinus, Pse

Carlos Sérgio, Agostinho; Angelo Antônio, Agostinho; Fernando, Pelicice; Deusimar Augusto de, Almeida; Elineide Eugênio, Marques.

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Fish ladders: safe fish passage or hotspot for predation?  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Passagens para peixes têm sido consideradas como estratégias para conservação da biodiversidade, visando além de assegurar os deslocamentos entre habitats fragmentados, atenuar a mortalidade por predação dos estratos populacionais que se concentram nos trechos imediatamente abaixo de barragens. Embo [...] ra a mortalidade por predação no trecho a jusante de reservatórios tenha sido bem investigada, especialmente sobre os juvenis de salmonídeos em movimentos descendentes, nada se sabe acerca da predação de peixes neotropicais em áreas de atração e confinamento de peixes, eventos comuns a essas facilidades de transposição. Nesse estudo são analisados aspectos da predação em um sistema de transposição de peixes (barragem de Lajeado, rio Tocantins, Brasil), buscando avaliar a abundância, a distribuição e o tempo de permanência de grandes peixes predadores na escada, as injúrias impostas por piranhas durante a passagem e a ocorrência de outros vertebrados predadores. Para isso foram realizadas amostragens a jusante, ao longo da escada, no trecho imediatamente acima da barragem e a montante do reservatório, utilizando redes de espera, tarrafas e contagens ou registros visuais durante o período de um ano (Novembro de 2002 a Outubro de 2003). Marcações com linha e missanga e registro de mutilações foram também realizados em concomitância. Peixes, aves, quelônios e cetáceos foram os principais grupos de predadores observados, com predomínio dos dois primeiros. A área nas imediações da entrada da escada, a jusante, foi a região com maior número de grandes predadores, sendo a única de relevância para vertebrados não peixes. Indivíduos marcados permaneceram na escada exercendo a piscivoria por até 90 dias. Rhaphiodon vulpinus, Hydrolycus armatus e Serrasalmus rhombeus foram os principais peixes predadores. Mutilações por ataques de Serrasalmus atingiram 36% das espécies e alcançaram 4% dos indivíduos no topo da escada. Os resultados sugerem que a alta densidade de peixes no ambiente restrito da escada, associada às injúrias sofridas no percurso e a presença de múltiplos predadores dotados de estratégias de predação variadas, transforme o corredor para passagem de peixes em um "hotspot" de predação Abstract in english Fish ladders are a strategy for conserving biodiversity, as they can provide connectivity between fragmented habitats and reduce predation on shoals that accumulate immediately below dams. Although the impact of predation downstream of reservoirs has been investigated, especially in juvenile salmoni [...] ds during their downstream movements, nothing is known about predation on Neotropical fish in the attraction and containment areas commonly found in translocation facilities. This study analysed predation in a fish passage system at the Lajeado Dam on the Tocantins River in Brazil. The abundance, distribution, and the permanence (time spent) of large predatory fish along the ladder, the injuries imposed by piranhas during passage and the presence of other vertebrate predators were investigated. From December 2002 to October 2003, sampling was conducted in four regions (downstream, along the ladder, in the forebay, and upstream of the reservoir) using gillnets, cast nets and counts or visual observations. The captured fish were tagged with thread and beads, and any mutilations were registered. Fish, birds and dolphins were the main predator groups observed, with a predominance of the first two groups. The entrance to the ladder, in the downstream region, was the area with the highest number of large predators and was the only region with relevant non-fish vertebrates. The main predatory fish species were Rhaphiodon vulpinus, Hydrolycus armatus, and Serrasalmus rhombeus. Tagged individuals were detected predating along the ladder for up to 90 days. Mutilations caused by Serrasalmus attacks were noted in 36% of species and 4% of individuals at the top of the ladder. Our results sugge

Angelo Antonio, Agostinho; Carlos Sergio, Agostinho; Fernando Mayer, Pelicice; Elineide Eugênio, Marques.

2012-10-01

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Chondrococcus columnaris disease of fishes: Influence of Columbia River fish ladders  

Energy Technology Data Exchange (ETDEWEB)

Mortalities in salmonid populations induced by Chondrococcus columnaris are usually associated with warm river water temperatures. Increasing use of the Columbia River for agriculture, industry and power will introduce additional added heat increments which could result,in additional growth of C. columnaris and proliferation of the disease. It is necessary, therefore, that we examine the existing environmental factors which contribute to the disease in the river. Proliferation and release of C. columnaris from fish ladders was demonstrated by the large number of organisms isolated from the Rocky Reach fish ladder on the Columbia River during 1965. The authors found that C. columnaris release into the water was related to the high incidence of infected coarse fishes and anadromous salmonids in the ladder. In this report, we will describe results which suggest that fish ladders may be important, sites for transferring the disease from fish indigenous to the Columbia River to migrating anadromous salmonids.

Fujihara, M.P.; Hungate, F.P.

1970-12-31

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Movements of adult Atlantic salmon in relation to a hydroelectric dam and fish ladder  

International Nuclear Information System (INIS)

The movements of adult Atlantic salmon were recorded as they approached, entered and ascended the pool-and-orifice fish ladder at Pitlochry Dam, Scotland. Thirty-nine returning salmon were captured in the River Tummel by rod-and-line angling, radio-tagged and released near where they were caught. The subsequent movements of each fish were then monitored. An electronic fish counter collected additional data on movements of untagged fish past a fixed point in the ladder. Of the 39 fish that were radio-tagged, 29 individuals were recorded approaching and ascending the ladder. The remaining fish either did not approach the dam (three fish), approached the dam after detailed tracking had ended (two fish), were recaptured by anglers (three fish), or the radio tags failed (two fish). Salmon released earlier in the year delayed longer before first approaching the dam. Delays between first approaching the dam and ascent of the ladder were greater for fish that approached the dam earlier. The majority of salmon visited the ladder entrance more than once (maximum 10 visits) before ascending. Having entered, all but four salmon ascended the fish ladder successfully on their first attempt. The four individuals that failed to do so succeeded on their second attempt. The rate at which salmon ascended the ladder was related directly to temperature. The shortest ascent time of a radio-tagged salmon was 5.25 h. Movements of eight of 11 tagged fish through the ladder ceased with the onsish through the ladder ceased with the onset of darkness but continued on the following morning. No radio-tagged fish entered the ladder at temperatures below 9oC. Similarly, few untagged fish were recorded ascending the ladder by the electronic fish counter at water temperatures below 8.5oC. Records from the fish counter indicated that 92% of upstream movements were made during daylight. (author)

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New Concepts in Fish Ladder Design: Analysis of Barriers to Upstream Fish Migration, Volume IV of IV, Investigation of the Physical and Biological Conditions Affecting Fish Passage Success at Culverts and Waterfalls, 1982-1984 Final Report.  

Energy Technology Data Exchange (ETDEWEB)

A synopsis of the project components was prepared to provide an overview for persons who are not fisheries scientists or engineers. This short report can be used also by technical persons who are interested in the scope of the project, and as a summary of the three main reports. The contents includes an historical perspective on fishway design which provides the basis for this project. The major project accomplishments and significant additions to the body of knowledge about the analysis and design of fishways are discussed. In the next section the research project organization, objectives and components are presented to familiarize the reader with the scope of this project. The summary report concludes with recommendations for assisting in the enhancement and restoration of fisheries resources from the perspective of fish passage problems and their solution. Promising research topics are included.

Powers, Patrick D.; Orsborn, John F.

1985-08-01

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Selection of an experimental fish ladder located at the dam of the Itaipu Binacional, Paraná River, Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available The specific selection of a weir and orifice type experimental fish ladder in the dam of the Itaipu Reservoir (Paraná River was evaluated by samplings in the river downstream and at two points along the ladder (at heights of 10 m and 27 m during 28 months. Among the 65 species recorded in the river (immediate downstream of the dam, 27 were captured on the ladder. The species that showed highest density on the ladder, the majority migratory, were moderately, or only slightly, abundant downstream. Among the most abundant species downstream, only one, non-migratory, was recorded in the ladder. The structure presented a negative selection in relation to large migratory pimelodids that might be overcome by enlarging the scale of its design. The sampling demonstrated a moderate selection of species along the ladder and its hydraulic model proved satisfactory regarding the attraction and efficient ascent of the fishes.A seleção específica de uma escada de peixes do tipo seqüência de tanques, com passagem de fundo (tipo weir and orifice, na barragem da hidrelétrica de Itaipu (rio Paraná, foi avaliada através de amostragens no rio a jusante (amostragem trimestral em 1997 e em dois pontos ao longo da escada (10 e 27m de altura; nov/94 a jan/97 e nov/94 a fev/97, respectivamente. Das 65 espécies registradas no rio imediatamente a jusante da barragem, 27 foram capturadas na escada. As espécies com maior densidade na escada, em sua maioria migradoras, tiveram abundância moderada ou baixa a jusante. Entre as mais abundantes a jusante, apenas uma, não migradora, foi registrada na escada. A escada apresentou seleção negativa aos grandes pimelodídeos migradores que pode ser superada com a ampliação na escala do projeto. As amostragens evidenciaram baixa seletividade específica ao longo da escada, sendo seu modelo hidráulico satisfatório na atração e eficiente na ascensão de peixes.

Domingo Rodriguez Fernandez

2004-08-01

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Selection of an experimental fish ladder located at the dam of the Itaipu Binacional, Paraná River, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A seleção específica de uma escada de peixes do tipo seqüência de tanques, com passagem de fundo (tipo weir and orifice), na barragem da hidrelétrica de Itaipu (rio Paraná), foi avaliada através de amostragens no rio a jusante (amostragem trimestral em 1997) e em dois pontos ao longo da escada (10 e [...] 27m de altura; nov/94 a jan/97 e nov/94 a fev/97, respectivamente). Das 65 espécies registradas no rio imediatamente a jusante da barragem, 27 foram capturadas na escada. As espécies com maior densidade na escada, em sua maioria migradoras, tiveram abundância moderada ou baixa a jusante. Entre as mais abundantes a jusante, apenas uma, não migradora, foi registrada na escada. A escada apresentou seleção negativa aos grandes pimelodídeos migradores que pode ser superada com a ampliação na escala do projeto. As amostragens evidenciaram baixa seletividade específica ao longo da escada, sendo seu modelo hidráulico satisfatório na atração e eficiente na ascensão de peixes. Abstract in english The specific selection of a weir and orifice type experimental fish ladder in the dam of the Itaipu Reservoir (Paraná River) was evaluated by samplings in the river downstream and at two points along the ladder (at heights of 10 m and 27 m) during 28 months. Among the 65 species recorded in the rive [...] r (immediate downstream of the dam), 27 were captured on the ladder. The species that showed highest density on the ladder, the majority migratory, were moderately, or only slightly, abundant downstream. Among the most abundant species downstream, only one, non-migratory, was recorded in the ladder. The structure presented a negative selection in relation to large migratory pimelodids that might be overcome by enlarging the scale of its design. The sampling demonstrated a moderate selection of species along the ladder and its hydraulic model proved satisfactory regarding the attraction and efficient ascent of the fishes.

Domingo Rodriguez, Fernandez; Angelo Antônio, Agostinho; Luis Mauricio, Bini.

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Fish passage post-construction issues: analysis of distribution, attraction and passage efficiency metrics at the Baguari Dam fish ladder to approach the problem  

Directory of Open Access Journals (Sweden)

Full Text Available Fish passages are considered the oldest management tool used to minimize the impact of blocking fish migratory routes by hydroelectric power plants. However, fish passages are being installed without specific criteria in Brazil, with severe consequences to the conservation of the local fish fauna. Therefore, basic data gathered for fish passages already constructed could contribute to define operational rules, in addition to offer subsidies to decision-making and design of future facilities. Thus, the fish ladder of Baguari Dam was evaluated regarding temporal distribution, attraction, and ascension of the local fish fauna. A total of 20 fish samples were conducted immediately downstream of the dam and inside the fish ladder, from January 2010 to June 2011. Seasonal variation in fish abundance and richness was registered below the dam and inside the passage, with higher number of migratory fish in the reproductive season (Kruskall-Wallis, p = 0.04 and p = 0.05. Furthermore, higher concentration of migratory allochthonous and non-migratory species was registered for the spill bay (Wilcoxon, p = 0.009 and p = 0.006 compared to the tailrace, where the fish ladder entrance is located. This result suggests low efficiency of the attraction system of the mechanism during the reproductive period. Once entering the fish ladder, migratory species apparently ascend the facility due to the similar distribution throughout different stretches. Generally, the results showed that an operational rule for the Baguari Dam fish ladder should consider running the facility only during the reproductive period, unless the objectives of the passage are well defined. The attraction system must be more precisely evaluated, using technologies such as radiotelemetry. Similarly, fish ascension also should be better analyzed to evaluate the time spent to ascend and its influence in the reproductive biology of the species using the ladder. Pit-tag system could be used to approach this analysis. It is expected that the discussion of these results would be useful for companies of the energy sector and for environmental agencies in Brazil, subsidizing decisions related to the management of fish passages already installed and to the construction of new facilities in the country.As passagens ou sistemas de transposição de peixes são uma das ferramentas de manejo mais antigas utilizadas para minimizar o impacto do bloqueio de rota migratória de peixes pela implantação de barragens. Todavia, sua implantação tem sido realizada sem muito critério no Brasil, trazendo consequências muitas vezes graves à conservação da ictiofauna local. Por essa razão, dados básicos obtidos para as passagens de peixes em funcionamento podem contribuir para definição de sua regra operativa, além de subsidiar tomada de decisões e o design de futuros sistemas. Assim, a escada de peixes da UHE Baguari foi avaliada quanto à distribuição temporal, atração e subida da ictiofauna local. Foram realizadas 20 amostragens a jusante da barragem e no interior da escada de peixes entre janeiro de 2010 a junho de 2011. Observou-se variação sazonal na distribuição e riqueza de espécies de peixes a jusante da barragem e dentro da escada, sendo que as espécies migradoras foram registradas em maior abundância durante o período reprodutivo (Kruskall-Wallis, p = 0,04 e p = 0,05. Além disso, nesse mesmo período, maior concentração das espécies migradoras alóctones e não migradoras foi registrada para a bacia de dissipação da barragem (Wilcoxon, p = 0,009 e p = 0,006 quando comparado ao canal de fuga, local onde se encontra a entrada da escada. Isso sugere que a eficiência do sistema de atração do mecanismo não seja a esperada nesse período. Uma vez dentro da escada, aparentemente as espécies migradoras percorrem todo o mecanismo, distribuindo-se de forma similar ao longo de sua extensão. Em geral, os resultados obtidos demonstram que, aparentemente, a regra operativa da escada deva indicar seu funcionamento apenas no período reprodutiv

Luiz Gustavo Martins da Silva

2012-10-01

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Deficient downstream passage through fish ladders: the case of Peixe Angical Dam, Tocantins River, Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A passagem descendente de peixes em mecanismos de transposição permanece pouco investigada na América do Sul. Inspirado nessa falha, o presente estudo monitorou a escada de peixes instalada na barragem da UHE Peixe Angical, alto rio Tocantins, entre setembro de 2009 e agosto de 2010. Para investigar [...] a extensão da passagem rio abaixo, a fauna de peixes foi amostrada mensalmente em (i) locais acima e abaixo da barragem, e (ii) dentro da escada. Para identificar corretamente movimentos ascendentes e descendentes dentro da escada, o mecanismo permaneceu aberto (fluxo permanente de água), mas uma tela impediu a passagem completa dos peixes em ambas as direções. Os resultados indicam que a escada é restritiva ao movimento dos peixes em ambos os sentidos, considerando que poucas espécies tiveram acesso ao mecanismo (de um total de 119 espécies na área, apenas 31 ocorreram na escada). O monitoramento revelou, entretanto, que a passagem descendente é consideravelmente mais limitada; apenas 18 espécies foram registradas descendo o mecanismo. Além disso, poucos peixes tentaram descer a escada ao longo do ano; de todos os peixes capturados na escada (n = 17,335), apenas 4% desempenhava movimentos descendentes. Espécies executando apenas movimentos descendentes tiveram baixa abundância ou foram infrequentes, e apenas quatro somaram quase toda captura. Enfatizamos que diversas espécies executaram movimentos exclusivos rio acima, ou apresentaram elevado fluxo de indivíduos subindo a escada. Consequentemente, a razão entre o número de peixes subindo e descendo o mecanismo (peixes/m²) apresentou valores positivos e elevados ao longo do ano (644:1 em média, considerando todas as espécies); espécies migradoras apresentaram valores ainda maiores (1069:1). A escada é, portanto, criticamente deficiente para a descida de peixes migradores e não-migradores, facultando apenas movimentos unilaterais rio acima. Concluímos que a escada de Peixe Angical não desempenha papel conservacionista, com risco de causar impactos sobre populações de peixes e complicar esforços alternativos de conservação. Abstract in english Downstream passage through fish ladders and other facilities remains largely uninvestigated in South America. In view of this concern, we monitored ascending and descending fish movements through the fish ladder at Peixe Angical Dam, upper Tocantins River, Brazil, between September 2009 and August 2 [...] 010. To investigate the extent of downstream passage, the fish fauna was sampled monthly (i) at sites upstream and downstream from the dam and (ii) inside the ladder. To distinguish between ascending and descending movements, the fish ladder remained open (permanent water flow), but a screen blocked the complete passage of fish in both directions. The results of the study indicated that the ladder restricts fish movements in both directions. Few species were found to use the ladder (31 out of 119 species recorded in the area). Moreover, monitoring revealed that downstream passage is even more limited. Only 18 species were recorded moving downstream. In addition, few fish attempted to move downstream during the year; of all fish captured in the ladder (n = 17,335), only 4% were descending. Species performing exclusive downstream movements were numerically rare or infrequent. Most downstream captures involved only four species. We emphasize that several species performed one-way upstream movements or showed a high density of ascending fish. Consequently, the numerical ratio between ascending and descending fish (ind./m²) showed high positive values throughout the year (644:1 on average, considering all species); migratory species showed higher ratios (1069:1). The results of the study show that the facility fails to support the downstream passage of migratory and non-migratory fishes. We conclude that the fish ladder at Peixe Angical Dam does not play a conservation role and may complicate alternative conservation efforts.

Fernando Mayer, Pelicice; Carlos Sérgio, Agostinho.

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New Concepts in Fish Ladder Design, Volume II of IV, Results of Laboratory and Field Research on New Concepts in Weir and Pool Fishways, 1982-1984 Final Project Report.  

Energy Technology Data Exchange (ETDEWEB)

A comprehensive review of fishway design practice led to new design concepts that had previously been untested. This concept was based on the observation that fish can be stimulated to leap when presented with certain hydraulic conditions. A laboratory test program was conducted to develop this concept into a new fishway configuration. Field testing revealed that components of the new design improved fish passage. Verification of the initial premise that fish can be stimulated to leap needs further study.

Aaserude, Robert G.; Orsborn, John F.

1985-08-01

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Fish ladder of Lajeado Dam: migrations on one-way routes?  

Directory of Open Access Journals (Sweden)

Full Text Available Fish ladders are generally conceived to reestablish connectivity among critical habitats for migratory species, thus mitigating the impacts of the blockage of migration routes by dams. If this management tool is to be meaningful for conserving fish species, it must provide a fully permeable connection and assure both upward and downward movements. However, because reservoirs have very different hydrodynamics than the original river, it is expected that, at least in the inner area, they may constitute an additional barrier to this movement, especially for descending fish. Thus, the present study sought to determine if migratory fish and their offspring disperse downstream from the dam after ascending a ladder and spawning in the upper reaches of a basin. To achieve this purpose, we evaluated the limitation imposed by lentic areas to the descent of eggs, larvae and adults of migratory species; we also determined the abundance and composition of larvae present in the plankton near the dam, and compared the intensity of the upward and downward movements of adult fish. Samples of ichthyoplankton were taken upriver, inside the reservoir, in the river downstream from the dam, and in the forebay of the Lajeado Dam on the Tocantins River (Luis Eduardo Magalhães Hydroelectric Plant, from October, 1999 through September, 2004. The densities of fish ascending and descending the ladder were determined experimentally on eight occasions, from June, 2004 to March, 2005. Due to difficulties in identifying the true fish origin (up or down in the environments connected by the fish passage system, the evaluation of the distribution of migratory fish in reservoirs was based on the landings of the commercial fishery conducted along the Itaipu Reservoir during the four years preceding (2001 through 2003 the construction of the lateral channel (fish-passage mechanism. Fish eggs and larvae drifting down the Tocantins River did not appear in samples taken in the lower half of the reservoir; those found in water flowing through the spillways, turbines or fish ladder of Lajeado Dam belonged essentially to non-migratory clupeids that spawn in the inner part of the reservoir. In addition, results showed that in a reservoir with no fish-passage mechanism, migrants select habitats that still maintain riverine characteristics, in the upper parts of the impounded area. The downward movements are negligible compared to those upward, in the experiments conducted in the fish ladder. It is concluded, therefore, that the Lajeado fish ladder, and possibly those at other dams, is essentially a one-way route that promotes upstream movements of migrants, without the necessary return of adults or their offspring. Thus, the low permeability of the connections provided by these management tools can drastically increase the level of environmental impact that they were actually intended to reduce.Escadas de peixes são geralmente concebidas para restabelecer a conectividade entre habitats críticos de espécies migradoras, atenuando os impactos da interceptação de rotas de migração por barragens. Para que esse instrumento de manejo tenha significado na conservação das espécies é necessário que a permeabilidade dessa conexão seja ampla e que os movimentos ascendentes e descendentes sejam assegurados. Entretanto, como os reservatórios têm uma hidrodinâmica muito distinta do rio original, postula-se que, pelo menos em sua área mais interna ele possa se constituir em uma barreira adicional a esses movimentos, especialmente os descendentes. Assim, esse trabalho busca avaliar se peixes migradores e sua prole dispersam para os trechos abaixo da barragem após a transporem e desovar nos trechos altos da bacia. Com esse propósito, foi avaliado o grau de restrição oferecido pelas áreas lênticas de reservatórios aos deslocamentos descendentes de ovos, larvas e adultos de espécies migradoras, identificada a abundância e composição das larvas presentes no plâncton das imediações da barragem e comparada a intensidade dos movimentos as

Angelo Antônio Agostinho

2007-01-01

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Fish passage post-construction issues: analysis of distribution, attraction and passage efficiency metrics at the Baguari Dam fish ladder to approach the problem  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese As passagens ou sistemas de transposição de peixes são uma das ferramentas de manejo mais antigas utilizadas para minimizar o impacto do bloqueio de rota migratória de peixes pela implantação de barragens. Todavia, sua implantação tem sido realizada sem muito critério no Brasil, trazendo consequênci [...] as muitas vezes graves à conservação da ictiofauna local. Por essa razão, dados básicos obtidos para as passagens de peixes em funcionamento podem contribuir para definição de sua regra operativa, além de subsidiar tomada de decisões e o design de futuros sistemas. Assim, a escada de peixes da UHE Baguari foi avaliada quanto à distribuição temporal, atração e subida da ictiofauna local. Foram realizadas 20 amostragens a jusante da barragem e no interior da escada de peixes entre janeiro de 2010 a junho de 2011. Observou-se variação sazonal na distribuição e riqueza de espécies de peixes a jusante da barragem e dentro da escada, sendo que as espécies migradoras foram registradas em maior abundância durante o período reprodutivo (Kruskall-Wallis, p = 0,04 e p = 0,05). Além disso, nesse mesmo período, maior concentração das espécies migradoras alóctones e não migradoras foi registrada para a bacia de dissipação da barragem (Wilcoxon, p = 0,009 e p = 0,006) quando comparado ao canal de fuga, local onde se encontra a entrada da escada. Isso sugere que a eficiência do sistema de atração do mecanismo não seja a esperada nesse período. Uma vez dentro da escada, aparentemente as espécies migradoras percorrem todo o mecanismo, distribuindo-se de forma similar ao longo de sua extensão. Em geral, os resultados obtidos demonstram que, aparentemente, a regra operativa da escada deva indicar seu funcionamento apenas no período reprodutivo, ao menos até que os objetivos da transposição de peixes na UHE Baguari sejam de fato definidos. Já o sistema de atração da escada deverá ser avaliado de forma mais precisa, utilizando-se tecnologias como radiotelemetria. Da mesma forma, a subida dos peixes pela escada deve ser melhor analisada para se avaliar o tempo gasto e a influência desse período sobre a biologia reprodutiva dos peixes. O sistema de Pit-tag pode ser utilizado para realizar essa análise. Espera-se que a discussão das informações obtidas no presente trabalho possa ser utilizada pelas empresas do setor elétrico e órgãos ambientais para subsidiar decisões relacionadas ao manejo de sistemas de transposição de peixes já em funcionamento e à construção de novos empreendimentos. Abstract in english Fish passages are considered the oldest management tool used to minimize the impact of blocking fish migratory routes by hydroelectric power plants. However, fish passages are being installed without specific criteria in Brazil, with severe consequences to the conservation of the local fish fauna. T [...] herefore, basic data gathered for fish passages already constructed could contribute to define operational rules, in addition to offer subsidies to decision-making and design of future facilities. Thus, the fish ladder of Baguari Dam was evaluated regarding temporal distribution, attraction, and ascension of the local fish fauna. A total of 20 fish samples were conducted immediately downstream of the dam and inside the fish ladder, from January 2010 to June 2011. Seasonal variation in fish abundance and richness was registered below the dam and inside the passage, with higher number of migratory fish in the reproductive season (Kruskall-Wallis, p = 0.04 and p = 0.05). Furthermore, higher concentration of migratory allochthonous and non-migratory species was registered for the spill bay (Wilcoxon, p = 0.009 and p = 0.006) compared to the tailrace, where the fish ladder entrance is located. This result suggests low efficiency of the attraction system of the mechanism during the reproductive period. Once entering the fish ladder, migratory species apparently ascend the facility due to the similar

Luiz Gustavo Martins da, Silva; Lorena Bettinelli, Nogueira; Bruno Pereira, Maia; Lucas Borges de, Resende.

2012-10-01

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Fish passage post-construction issues: analysis of distribution, attraction and passage efficiency metrics at the Baguari Dam fish ladder to approach the problem  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese As passagens ou sistemas de transposição de peixes são uma das ferramentas de manejo mais antigas utilizadas para minimizar o impacto do bloqueio de rota migratória de peixes pela implantação de barragens. Todavia, sua implantação tem sido realizada sem muito critério no Brasil, trazendo consequênci [...] as muitas vezes graves à conservação da ictiofauna local. Por essa razão, dados básicos obtidos para as passagens de peixes em funcionamento podem contribuir para definição de sua regra operativa, além de subsidiar tomada de decisões e o design de futuros sistemas. Assim, a escada de peixes da UHE Baguari foi avaliada quanto à distribuição temporal, atração e subida da ictiofauna local. Foram realizadas 20 amostragens a jusante da barragem e no interior da escada de peixes entre janeiro de 2010 a junho de 2011. Observou-se variação sazonal na distribuição e riqueza de espécies de peixes a jusante da barragem e dentro da escada, sendo que as espécies migradoras foram registradas em maior abundância durante o período reprodutivo (Kruskall-Wallis, p = 0,04 e p = 0,05). Além disso, nesse mesmo período, maior concentração das espécies migradoras alóctones e não migradoras foi registrada para a bacia de dissipação da barragem (Wilcoxon, p = 0,009 e p = 0,006) quando comparado ao canal de fuga, local onde se encontra a entrada da escada. Isso sugere que a eficiência do sistema de atração do mecanismo não seja a esperada nesse período. Uma vez dentro da escada, aparentemente as espécies migradoras percorrem todo o mecanismo, distribuindo-se de forma similar ao longo de sua extensão. Em geral, os resultados obtidos demonstram que, aparentemente, a regra operativa da escada deva indicar seu funcionamento apenas no período reprodutivo, ao menos até que os objetivos da transposição de peixes na UHE Baguari sejam de fato definidos. Já o sistema de atração da escada deverá ser avaliado de forma mais precisa, utilizando-se tecnologias como radiotelemetria. Da mesma forma, a subida dos peixes pela escada deve ser melhor analisada para se avaliar o tempo gasto e a influência desse período sobre a biologia reprodutiva dos peixes. O sistema de Pit-tag pode ser utilizado para realizar essa análise. Espera-se que a discussão das informações obtidas no presente trabalho possa ser utilizada pelas empresas do setor elétrico e órgãos ambientais para subsidiar decisões relacionadas ao manejo de sistemas de transposição de peixes já em funcionamento e à construção de novos empreendimentos. Abstract in english Fish passages are considered the oldest management tool used to minimize the impact of blocking fish migratory routes by hydroelectric power plants. However, fish passages are being installed without specific criteria in Brazil, with severe consequences to the conservation of the local fish fauna. T [...] herefore, basic data gathered for fish passages already constructed could contribute to define operational rules, in addition to offer subsidies to decision-making and design of future facilities. Thus, the fish ladder of Baguari Dam was evaluated regarding temporal distribution, attraction, and ascension of the local fish fauna. A total of 20 fish samples were conducted immediately downstream of the dam and inside the fish ladder, from January 2010 to June 2011. Seasonal variation in fish abundance and richness was registered below the dam and inside the passage, with higher number of migratory fish in the reproductive season (Kruskall-Wallis, p = 0.04 and p = 0.05). Furthermore, higher concentration of migratory allochthonous and non-migratory species was registered for the spill bay (Wilcoxon, p = 0.009 and p = 0.006) compared to the tailrace, where the fish ladder entrance is located. This result suggests low efficiency of the attraction system of the mechanism during the reproductive period. Once entering the fish ladder, migratory species apparently ascend the facility due to the similar

Luiz Gustavo Martins da, Silva; Lorena Bettinelli, Nogueira; Bruno Pereira, Maia; Lucas Borges de, Resende.

18

Design and construction of double-sided silicon ladders for the L3 microvertex detector  

International Nuclear Information System (INIS)

The techniques used in the construction of the double-sided ladders for the L3 Silicon Microvertex Detector (SMD) are presented. The detector consists of two cylindrical layers, each of 12 ladders, with double-sided silicon detectors which provide r-phi and z coordinates measurements. This description includes ladder mechanical design and the assembly. A novel solution to readout the z-coordinates is presented. It optimizes very effectively the removal of heat generated by the readout electronics and minimizes the radiation length in the central region. Some results from the survey of the individual ladders are also discussed. (orig.)

19

Design and construction of double-sided silicon ladders for the L3 microvertex detector  

Energy Technology Data Exchange (ETDEWEB)

The techniques used in the construction of the double-sided ladders for the L3 Silicon Microvertex Detector (SMD) are presented. The detector consists of two cylindrical layers, each of 12 ladders, with double-sided silicon detectors which provide r-phi and z coordinates measurements. This description includes ladder mechanical design and the assembly. A novel solution to readout the z-coordinates is presented. It optimizes very effectively the removal of heat generated by the readout electronics and minimizes the radiation length in the central region. Some results from the survey of the individual ladders are also discussed. (orig.)

Ambrosi, G.; Babucci, E.; Battiston, R.; Biasini, M.; Easo, S.; Krastev, V.; Pauluzzi, M.; Santocchia, A.; Bay, A.; Burger, W.J.; Extermann, P.; Perrin, E.; Susinno, G.; Brooks, M.; Kapustinsky, J.S.; Kinnison, W.W.; Lee, D.M.; Mills, G.B.; Thompson, T.C.; DiBitonto, D.; Pennington, T.; Subhani, K.; Hauviller, C. (Univ. Degli Studi di Perugia (Italy) INFN, Perugia (Italy) Univ. of Geneva (Switzerland) Los Alamos National Lab., Los Alamos, NM (United States) Univ. of Alabama, Tuscaloosa, AL (United States) European Lab. for Particle Physics (CERN), Geneva (Switzerland))

1994-04-21

20

Utilization of the fish ladder at the Engenheiro Sergio Motta Dam, Brazil, by long distance migrating potamodromous species  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese A utilização da escada para peixes instalada na barragem Engenheiro Sergio Motta (também conhecida como Porto Primavera) no rio Paraná, no sudeste do Brasil, por espécies potamódromas de longa distância (protocolo I) e os movimentos ascendentes e descendentes (protocolo II) foram avaliados. Três tan [...] ques ao longo da escada para peixes (denominados como foz, meio e tomada) foram amostrados mensalmente entre dezembro de 2004 a março de 2005 para avaliar a abundância de espécies na escada. Os movimentos ascendentes e descendentes das espécies na escada foram analisados no mesmo período. Nas amostragens relativas aos protocolo I e II, foram capturadas 37 espécies representando 17 famílias e cinco ordens (Characiformes, Siluriformes, Perciformes, Gymnotiformes e Myliobatiformes). Os Characiformes foram representados por 21 espécies. Espécies migradoras de longa distância (11 espécies) predominaram (60% do total), com maior abundância de Rhinelepis aspera (5645 indivíduos). A abundância média variou entre os meses e tanques para o protocolo I, com menores valores em dezembro e março para todos os tanques, e maiores em janeiro no tanque foz, devido a maior captura de R. aspera. A abundância de peixes diminuiu do tanque foz para o tanque tomada, especialmente para R. aspera e Rhaphiodon vulpinus. Nas capturas relativas ao protocolo II, foram capturadas 17 espécies ascendendo a escada: Astyanax altiparanae e Leporinus friderici foram as mais abundantes (com 684 e 111 indivíduos, respectivamente). Entretanto, 18 espécies apresentaram movimentos descendentes, com elevadas capturas de Metynnis maculatus e A. altiparanae (339 e 319 indivíduos, respectivamente). Doze espécies apresentaram movimentos ascendentes e descendentes na escada, e das sete espécies migradoras amostradas, quatro apresentaram movimentos para cima e para baixo, e três espécies somente subiram. Esta escada para peixes parece favorecer seletivamente espécies com elevada capacidade de natação. As necessidades de pesquisas futuras para elucidar sobre a atratividade da escada, movimentos descendentes, utilização da escada pelos peixes e os impactos sobre as áreas de reprodução e criadouros, ambos a montante e jusante da barragem, são discutidos. Abstract in english Utilization of the fish ladder installed at the Engenheiro Sergio Motta Dam (also known as Porto Primavera) on the Paraná River, Southern Brazil, by long-distance migrating potamodromous species (sampling Protocol I), and ascending and descending movements (Protocol II) were evaluated. Three pools a [...] long the fish ladder (designated as lower, middle, and upper) were sampled monthly between December, 2004 and March, 2005 to determine the abundance of species in the ladder. The ascending and descending movements of the species in the ladder were also analyzed in the same period. In the samples for both protocols, 37 species representing 17 families and 5 orders (Characiformes, Siluriformes, Perciformes, Gymnotiformes, and Myliobatiformes) were recorded. Characiformes were represented by 21 species. Long- distance migratory species (11 species) predominated in the ladder (60% of the total number of individuals), with high abundance of Rhinelepis aspera (5645 individuals). For protocol I, mean abundance varied greatly among the months and pools, with lowest values in December and March for all pools, and highest in January for the lower pool due to high capture of R. aspera. Fish abundance declined from the lower to the upper pool, especially for R. aspera and Rhaphiodon vulpinus. For Protocol II, 17 species were recorded ascending the ladder, where Astyanax altiparanae and Leporinus friderici were the most abundant species (684 and 111 individuals, respectively). However, 18 species showed descending movements, with high captures of Metynnis maculatus and A. altiparanae (339 and 319 individuals, respectively). Twelve species (52%) moved in both directions, and among the seven migra

Sérgio, Makrakis; Maristela Cavicchioli, Makrakis; Ricardo Luiz, Wagner; João Henrique Pinheiro, Dias; Luiz Carlos, Gomes.

 
 
 
 
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Diel variation in the ascent of fishes up an experimental fish ladder at Itaipu Reservoir: fish size, reproductive stage and taxonomic group influences  

Directory of Open Access Journals (Sweden)

Full Text Available In this study, we evaluated the fish ascent in the experimental ladder at Itaipu Reservoir (Paraná State, Brazil, in relation to diel variation, fish size, reproductive stages and species composition. The study was carried out from October, 1995 to February, 1996 and from November, 1996 to January, 1997 at two points on the ladder (boxes at heights of 10 and 27 m. Twenty-two species were recorded, and Prochilodus lineatus, Pimelodus maculatus, Leporinus obtusidens, Schizodon borellii and Leporinus friderici accounted for 86.6 % of the total catch. Fish length did not differ between diel periods and boxes. On the other hand, fish abundance of the main species was significantly influenced by box position, reproductive stage and diel period. The higher box showed lower abundance, suggesting some selectivity in ascension. The ability to ascend the ladder did not show any relationship with reproductive migration, since non-reproductive adults comprised most of the catch. An interesting finding is that the major taxonomic groups showed specific diel preferences in ascending the ladder: Characiformes ascended the ladder predominantly during daylight, whereas Siluriformes migrated at night. These results emphasize how complex ladders are as management tools, and stress the need to acquire information on several aspects as a condition to achieve conservation goals.Nesse estudo, a transposição de peixes na escada experimental do reservatório de Itaipu (Paraná, Brasil foi avaliada em relação à variação diária, tamanho dos peixes, estágios reprodutivos e a composição das espécies. O estudo foi conduzido de Outubro de 1995 a Fevereiro de 1996, e de Novembro de 1996 a Janeiro de 1997, em dois trechos da escada (caixas a 10 e 27 m de altura. Vinte e duas espécies foram registradas, e Prochilodus lineatus, Pimelodus maculatus, Leporinus obtusidens, Schizodon borellii e Leporinus friderici compuseram 86,6% das capturas. O tamanho dos peixes não diferiu entre os períodos do dia e caixas. Por outro lado, a abundância das principais espécies foi significativamente influenciada pela posição das caixas, estágio de reprodução e período do dia. A caixa superior tendeu a apresentar menor abundância de peixes, sugerindo certa seletividade na subida. A habilidade em ascender a escada não esteve relacionada com a migração reprodutiva, visto que adultos não-reprodutivos compuseram a maior parte das capturas. Um padrão interessante foi a preferência, apresentada pelos grandes grupos taxonômicos, por períodos específicos do dia na ascensão da escada: os Characiformes subiram a escada predominantemente durante o dia, enquanto os Siluriformes durante a noite. Esses resultados enfatizam o quão complexas são as escadas como ferramentas de manejo, e realçam a necessidade de ampliar o nível de informações sobre diversos aspectos como condição chave para que metas conservacionistas sejam alcançadas.

Domingo Rodriguez Fernandez

2007-01-01

22

Design a Fish  

Science.gov (United States)

In this activity (page 2 of PDF), learners will study the adaptations different fish species have developed to survive in their habitats. Using basic craft supplies, learners will construct a 3D fish exhibiting these traits, or even design their own fish and detail how it has adapted to another world, then present their fish to the class. Relates to the linked video, DragonflyTV GPS: Alligator Habitat.

Twin Cities Public Television, Inc.

2007-01-01

23

Diel variation in the ascent of fishes up an experimental fish ladder at Itaipu Reservoir: fish size, reproductive stage and taxonomic group influences  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Nesse estudo, a transposição de peixes na escada experimental do reservatório de Itaipu (Paraná, Brasil) foi avaliada em relação à variação diária, tamanho dos peixes, estágios reprodutivos e a composição das espécies. O estudo foi conduzido de Outubro de 1995 a Fevereiro de 1996, e de Novembro de 1 [...] 996 a Janeiro de 1997, em dois trechos da escada (caixas a 10 e 27 m de altura). Vinte e duas espécies foram registradas, e Prochilodus lineatus, Pimelodus maculatus, Leporinus obtusidens, Schizodon borellii e Leporinus friderici compuseram 86,6% das capturas. O tamanho dos peixes não diferiu entre os períodos do dia e caixas. Por outro lado, a abundância das principais espécies foi significativamente influenciada pela posição das caixas, estágio de reprodução e período do dia. A caixa superior tendeu a apresentar menor abundância de peixes, sugerindo certa seletividade na subida. A habilidade em ascender a escada não esteve relacionada com a migração reprodutiva, visto que adultos não-reprodutivos compuseram a maior parte das capturas. Um padrão interessante foi a preferência, apresentada pelos grandes grupos taxonômicos, por períodos específicos do dia na ascensão da escada: os Characiformes subiram a escada predominantemente durante o dia, enquanto os Siluriformes durante a noite. Esses resultados enfatizam o quão complexas são as escadas como ferramentas de manejo, e realçam a necessidade de ampliar o nível de informações sobre diversos aspectos como condição chave para que metas conservacionistas sejam alcançadas. Abstract in english In this study, we evaluated the fish ascent in the experimental ladder at Itaipu Reservoir (Paraná State, Brazil), in relation to diel variation, fish size, reproductive stages and species composition. The study was carried out from October, 1995 to February, 1996 and from November, 1996 to January, [...] 1997 at two points on the ladder (boxes at heights of 10 and 27 m). Twenty-two species were recorded, and Prochilodus lineatus, Pimelodus maculatus, Leporinus obtusidens, Schizodon borellii and Leporinus friderici accounted for 86.6 % of the total catch. Fish length did not differ between diel periods and boxes. On the other hand, fish abundance of the main species was significantly influenced by box position, reproductive stage and diel period. The higher box showed lower abundance, suggesting some selectivity in ascension. The ability to ascend the ladder did not show any relationship with reproductive migration, since non-reproductive adults comprised most of the catch. An interesting finding is that the major taxonomic groups showed specific diel preferences in ascending the ladder: Characiformes ascended the ladder predominantly during daylight, whereas Siluriformes migrated at night. These results emphasize how complex ladders are as management tools, and stress the need to acquire information on several aspects as a condition to achieve conservation goals.

Domingo Rodriguez, Fernandez; Angelo Antonio, Agostinho; Luis Mauricio, Bini; Fernando Mayer, Pelicice.

24

Fish ladder of Lajeado Dam: migrations on one-way routes?  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Escadas de peixes são geralmente concebidas para restabelecer a conectividade entre habitats críticos de espécies migradoras, atenuando os impactos da interceptação de rotas de migração por barragens. Para que esse instrumento de manejo tenha significado na conservação das espécies é necessário que [...] a permeabilidade dessa conexão seja ampla e que os movimentos ascendentes e descendentes sejam assegurados. Entretanto, como os reservatórios têm uma hidrodinâmica muito distinta do rio original, postula-se que, pelo menos em sua área mais interna ele possa se constituir em uma barreira adicional a esses movimentos, especialmente os descendentes. Assim, esse trabalho busca avaliar se peixes migradores e sua prole dispersam para os trechos abaixo da barragem após a transporem e desovar nos trechos altos da bacia. Com esse propósito, foi avaliado o grau de restrição oferecido pelas áreas lênticas de reservatórios aos deslocamentos descendentes de ovos, larvas e adultos de espécies migradoras, identificada a abundância e composição das larvas presentes no plâncton das imediações da barragem e comparada a intensidade dos movimentos ascendentes e descendentes de peixes. Foram realizadas amostragens de ictioplâncton a montante, no reservatório e em seu trecho a jusante, bem como nas imediações da barragem de Lajeado (rio Tocantins; UHE Luis Eduardo Magalhães) durante o período de outubro de 1999 a setembro de 2004 e determinado, experimentalmente, em oito ocasiões durante o período de junho de 2004 e março de 2005, a densidade de peixes em movimentos ascendentes e descendentes na escada de peixes desse reservatório. Já a avaliação na distribuição de peixes migradores em reservatórios foi baseada no acompanhamento dos desembarques da pesca comercial praticada ao longo do reservatório de Itaipu durante os quatro anos que precederam a construção do mecanismo de transposição atualmente existente (2001 a 2003). Os resultados obtidos demonstraram que os ovos e larvas de peixes em deriva, pelo rio Tocantins, desaparecem das amostras na metade inferior do reservatório e aqueles encontrados na água vertida ou turbinada pela barragem de Lajeado e na escada de peixes pertencem, essencialmente, a clupeídeos não migradores, com desovas nas áreas internas do reservatório. Revelam ainda que, em reservatório sem mecanismo de transposição, os peixes migradores selecionam habitats que ainda mantém características fluviais, nos segmentos superiores da área represada. Os experimentos realizados na escada revelam que os movimentos descendentes são irrelevantes quando comparados aos ascendentes. Conclui-se, portanto, que a escada de peixes de Lajeado, e possivelmente de várias outras barragens, é essencialmente uma via de mão única que promove subidas massivas de migrantes sem o almejado retorno de adultos ou de sua prole. Assim, a baixa permeabilidade das conexões proporcionadas por esses instrumentos de manejo pode aumentar drasticamente o nível do impacto ambiental para cuja atenuação ele foi concebido. Abstract in english Fish ladders are generally conceived to reestablish connectivity among critical habitats for migratory species, thus mitigating the impacts of the blockage of migration routes by dams. If this management tool is to be meaningful for conserving fish species, it must provide a fully permeable connecti [...] on and assure both upward and downward movements. However, because reservoirs have very different hydrodynamics than the original river, it is expected that, at least in the inner area, they may constitute an additional barrier to this movement, especially for descending fish. Thus, the present study sought to determine if migratory fish and their offspring disperse downstream from the dam after ascending a ladder and spawning in the upper reaches of a basin. To achieve this purpose, we evaluated the limitation imposed by lentic areas to the descent of eggs, larvae and adults of

Angelo Antônio, Agostinho; Elineide Eugênio, Marques; Carlos Sérgio, Agostinho; Deusimar Augusto de, Almeida; Rafael José de, Oliveira; Jussiclene Rodrigues Bezerra de, Melo.

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Comparing on site human and video counts at Igarapava fish ladder, south eastern Brazil  

Directory of Open Access Journals (Sweden)

Full Text Available On site human observations and video images were collected and compared at the window of the Igarapava Dam fish ladder (IDFL, rio Grande , Southeastern Brazil, between March 1st and June 30th, 2004. We conducted four experiments with two humans (Observer 1 and Observer 2 observing fish passage in the IDFL window while a Sony 3CCD video camera (Observer 3 recorded fish passage at the same time. Experiments, each one hour in length, were distributed throughout the diel cycle using full spectrum lights. We identified fish species, the number of individuals for each species, and the real time that they passed. Counts from each human observer were compared to the video counts. The fish species most commonly observed in the window were - curimba (Prochilodus lineatus, mandi-amarelo (Pimelodus maculatus, piau-três-pintas (Leporinus friderici and ferreirinha (Leporinus octofasciatus. The number of species and individuals were indistinguishable for the three observers. But, the number of species and individuals were significantly different among experiments. Thus, the three observers register the same number of species and count the same number of individuals even when these two response variables differ significantly among experiments. Based on these results, we concluded that the video count was an accurate method to assess fish passage at the IDFL.Observações in loco e vídeo filmagens foram coletadas na janela da escada de peixes da UHE Igarapava (EPUG, rio Grande, sudeste do Brasil, entre 1º de março e 30 junho de 2004. Realizaram-se quatro experimentos com dois observadores humanos (Observador 1 e Observador 2 que observaram a passagem de peixes na janela da EPUG enquanto uma vídeo câmera Sony 3CCD (Observador 3 registrou simultaneamente a passagem de peixes. Os dois observadores humanos registraram in situ a passagem de peixes no visor da escada enquanto a câmera os filmava ao mesmo tempo. Os experimentos, cada um com uma hora de duração, foram realizados durante o ciclo diário, utilizando-se iluminação de espectro completo. Registraram-se as espécies, o número de indivíduos e o horário de passagem. Os registros de cada observador humano in situ foram comparados com os dos vídeos. Consideraram-se curimba (Prochilodus lineatus, mandi-amarelo (Pimelodus maculatus, piau-três-pintas (Leporinus friderici e ferreirinha (Leporinus octofasciatus como espécies alvo, tendo em vista sua alta freqüência de ocorrência na escada de peixes da UHE Igarapava. O número de espécies e o número de indivíduos não foram estatisticamente diferentes entre observadores. Por outro lado, o número de espécies e o número de indivíduos que passaram pelo visor foram estatisticamente diferentes entre experimentos. Assim, demonstrou-se que os três observadores registraram o mesmo número de espécies e contaram o mesmo número de indivíduos, mesmo quando as duas variáveis diferiram significativamente entre experimentos. Concluiu-se que o sistema de vídeo imagem constitui um método eficaz para avaliação da passagem de peixes na escada de peixes de Igarapava.

Mark D. Bowen

2006-06-01

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Comparing on site human and video counts at Igarapava fish ladder, south eastern Brazil  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Observações in loco e vídeo filmagens foram coletadas na janela da escada de peixes da UHE Igarapava (EPUG), rio Grande, sudeste do Brasil, entre 1º de março e 30 junho de 2004. Realizaram-se quatro experimentos com dois observadores humanos (Observador 1 e Observador 2) que observaram a passagem de [...] peixes na janela da EPUG enquanto uma vídeo câmera Sony 3CCD (Observador 3) registrou simultaneamente a passagem de peixes. Os dois observadores humanos registraram in situ a passagem de peixes no visor da escada enquanto a câmera os filmava ao mesmo tempo. Os experimentos, cada um com uma hora de duração, foram realizados durante o ciclo diário, utilizando-se iluminação de espectro completo. Registraram-se as espécies, o número de indivíduos e o horário de passagem. Os registros de cada observador humano in situ foram comparados com os dos vídeos. Consideraram-se curimba (Prochilodus lineatus), mandi-amarelo (Pimelodus maculatus), piau-três-pintas (Leporinus friderici) e ferreirinha (Leporinus octofasciatus) como espécies alvo, tendo em vista sua alta freqüência de ocorrência na escada de peixes da UHE Igarapava. O número de espécies e o número de indivíduos não foram estatisticamente diferentes entre observadores. Por outro lado, o número de espécies e o número de indivíduos que passaram pelo visor foram estatisticamente diferentes entre experimentos. Assim, demonstrou-se que os três observadores registraram o mesmo número de espécies e contaram o mesmo número de indivíduos, mesmo quando as duas variáveis diferiram significativamente entre experimentos. Concluiu-se que o sistema de vídeo imagem constitui um método eficaz para avaliação da passagem de peixes na escada de peixes de Igarapava. Abstract in english On site human observations and video images were collected and compared at the window of the Igarapava Dam fish ladder (IDFL), rio Grande , Southeastern Brazil, between March 1st and June 30th, 2004. We conducted four experiments with two humans (Observer 1 and Observer 2) observing fish passage in [...] the IDFL window while a Sony 3CCD video camera (Observer 3) recorded fish passage at the same time. Experiments, each one hour in length, were distributed throughout the diel cycle using full spectrum lights. We identified fish species, the number of individuals for each species, and the real time that they passed. Counts from each human observer were compared to the video counts. The fish species most commonly observed in the window were - curimba (Prochilodus lineatus), mandi-amarelo (Pimelodus maculatus), piau-três-pintas (Leporinus friderici) and ferreirinha (Leporinus octofasciatus). The number of species and individuals were indistinguishable for the three observers. But, the number of species and individuals were significantly different among experiments. Thus, the three observers register the same number of species and count the same number of individuals even when these two response variables differ significantly among experiments. Based on these results, we concluded that the video count was an accurate method to assess fish passage at the IDFL.

Mark D., Bowen; Simone, Marques; Luiz G. M., Silva; Volney, Vono; Hugo P., Godinho.

27

Fish passage post-construction issues: analysis of distribution, attraction and passage efficiency metrics at the Baguari Dam fish ladder to approach the problem  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Fish passages are considered the oldest management tool used to minimize the impact of blocking fish migratory routes by hydroelectric power plants. However, fish passages are being installed without specific criteria in Brazil, with severe consequences to the conservation of the local fish fauna. Therefore, basic data gathered for fish passages already constructed could contribute to define operational rules, in addition to offer subsidies to decision-making and design of future facilities. ...

Luiz Gustavo Martins da Silva; Lorena Bettinelli Nogueira; Bruno Pereira Maia; Lucas Borges de Resende

2012-01-01

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Environmental factors related to entry into and ascent of fish in the experimental ladder located close to Itaipu Dam  

Directory of Open Access Journals (Sweden)

Full Text Available We evaluated the seasonality of the ascent of fish in an experimental ladder located close to Itaipu Dam, and its relationships to reproduction, temperature, river level and discharge. Samplings of fish and measurements of abiotic factors were performed from February, 1995 through January, 1997, in two resting pools of the ladder. Pool A was located 10 m above the mean level of the Paraná River; Pool B was located at the upper end of the ladder, at a height of 27 m. Autoregressive models were used to remove the temporal dependence between observations. Residuals of the models were used to relate, using Pearson's correlation coefficient, the densities of fish to the environmental variables. Clear patterns of seasonality were observed for temperature. River level, turbine discharge and spillway discharge, although they showed no clear seasonal dynamics, were time-dependent, because the autocorrelation coefficients for different k values were significant. In the samples of larger-sized fish, 23 species were recorded during the two years of study. Most of the individuals were in a non reproductive state, and about 90% of the individuals belonged to only six species. The temporal variability in total abundance, considering all species, indicated a pattern of seasonal variation; high abundances occurred from October through February (75% and in Pool A (61% of the 1343 individuals sampled. Low abundances were recorded during winter, with the correlogram of total density confirming this tendency. In the samples of smaller-sized species, six species were recorded, with all six present in both pools, but more frequent in the first pool (64%. Bryconamericus stramineus comprised 99% of the total numbers of smaller fish in the samples. The total abundance of small species showed different temporal patterns of seasonal variation in the two years of study.O presente estudo avalia a sazonalidade da ascensão de peixes na escada experimental localizada junto à barragem da hidrelétrica de Itaipu e as relações com a reprodução, temperatura, nível do rio e suas vazões. As amostragens de peixes e de fatores abióticos foram obtidas de fevereiro de 1995 a janeiro de 1997, em dois tanques de descanso, aqui denominados Caixas, sendo o primeiro, Caixa A, localizado na altura de 10 m da cota média do rio Paraná, e o segundo, Caixa B, ao final da escada, a 27 m de altura. Modelos autoregressivos foram empregados com o objetivo de remover a dependência temporal entre as observações. Posteriormente, os resíduos dos modelos foram utilizados para relacionar, através do coeficiente de correlação de Pearson, as densidades de peixes com as variáveis ambientais. Padrões claros de sazonalidade foram observados para a variável temperatura. As variáveis cota, vazão turbinada e vazão vertida, embora não tenham apresentado dinâmicas sazonais claras, foram temporalmente dependentes, tendo em vista que os coeficientes de autocorrelação, para diferentes k, foram significativos. Na amostragem de peixes de maior porte foram registradas 23 espécies ao longo dos dois anos de estudo, sendo que a maior parte dos indivíduos não se encontrava em reprodução e cerca de 90% dos indivíduos amostrados pertenciam a apenas seis espécies. A variabilidade temporal da abundância total, considerando o conjunto das espécies, indicou um padrão de variação sazonal, permitindo evidenciar que os maiores valores de abundância foram observados sistematicamente nos meses de outubro a fevereiro (75% e na caixa A (61% dos 1343 indivíduos amostrados. Os menores valores foram registrados nos meses de inverno. O correlograma da densidade total confirma essa tendência. Nas amostragens destinadas às espécies de pequeno porte, foram registradas seis espécies, todas presentes em ambas as caixas, sendo mais freqüentes na primeira (64%. Entre essas espécies, Bryconamericus stramineus contribuiu com 99% do total amostrado. A variabilidade temporal da abundância total das espécies de pequeno porte indicou um padrão distinto de varia

Domingo Rodrigues Fernandez

2007-01-01

29

Design of narrow bandwidth ladder-type filters with sharp transition bands using mutually connected resonator elements.  

Science.gov (United States)

This paper proposes a new design technique for a ladder-type filter to reduce the passband width without sacrificing the insertion loss, out-of-band rejection, and steepness of the transition bands. First, it is shown that 2 transmission zeros can be generated by connecting an additional resonator in either series or parallel arm of the ladder filter topology. This new filter topology can be designed systematically by the derived-m transformation. Second, it is demonstrated that the narrow bandwidth, sharp transition bands, and large out-of- band rejection are simultaneously realized by applying the present technique to specifically designed ladder-type filters. Finally, this technique is applied to the design of a SAW filter fabricated on the Cu-grating/15 degrees YX-LiNbO3 structure. PMID:19574155

Komatsu, Tomoya; Tanaka, Yasutomo; Hashimoto, Ken-ya; Omori, Tatsuya; Yamaguchi, Masatsune

2009-07-01

30

Environmental factors related to entry into and ascent of fish in the experimental ladder located close to Itaipu Dam  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O presente estudo avalia a sazonalidade da ascensão de peixes na escada experimental localizada junto à barragem da hidrelétrica de Itaipu e as relações com a reprodução, temperatura, nível do rio e suas vazões. As amostragens de peixes e de fatores abióticos foram obtidas de fevereiro de 1995 a jan [...] eiro de 1997, em dois tanques de descanso, aqui denominados Caixas, sendo o primeiro, Caixa A, localizado na altura de 10 m da cota média do rio Paraná, e o segundo, Caixa B, ao final da escada, a 27 m de altura. Modelos autoregressivos foram empregados com o objetivo de remover a dependência temporal entre as observações. Posteriormente, os resíduos dos modelos foram utilizados para relacionar, através do coeficiente de correlação de Pearson, as densidades de peixes com as variáveis ambientais. Padrões claros de sazonalidade foram observados para a variável temperatura. As variáveis cota, vazão turbinada e vazão vertida, embora não tenham apresentado dinâmicas sazonais claras, foram temporalmente dependentes, tendo em vista que os coeficientes de autocorrelação, para diferentes k, foram significativos. Na amostragem de peixes de maior porte foram registradas 23 espécies ao longo dos dois anos de estudo, sendo que a maior parte dos indivíduos não se encontrava em reprodução e cerca de 90% dos indivíduos amostrados pertenciam a apenas seis espécies. A variabilidade temporal da abundância total, considerando o conjunto das espécies, indicou um padrão de variação sazonal, permitindo evidenciar que os maiores valores de abundância foram observados sistematicamente nos meses de outubro a fevereiro (75%) e na caixa A (61% dos 1343 indivíduos amostrados). Os menores valores foram registrados nos meses de inverno. O correlograma da densidade total confirma essa tendência. Nas amostragens destinadas às espécies de pequeno porte, foram registradas seis espécies, todas presentes em ambas as caixas, sendo mais freqüentes na primeira (64%). Entre essas espécies, Bryconamericus stramineus contribuiu com 99% do total amostrado. A variabilidade temporal da abundância total das espécies de pequeno porte indicou um padrão distinto de variação sazonal entre dois períodos anuais analisados. Abstract in english We evaluated the seasonality of the ascent of fish in an experimental ladder located close to Itaipu Dam, and its relationships to reproduction, temperature, river level and discharge. Samplings of fish and measurements of abiotic factors were performed from February, 1995 through January, 1997, in [...] two resting pools of the ladder. Pool A was located 10 m above the mean level of the Paraná River; Pool B was located at the upper end of the ladder, at a height of 27 m. Autoregressive models were used to remove the temporal dependence between observations. Residuals of the models were used to relate, using Pearson's correlation coefficient, the densities of fish to the environmental variables. Clear patterns of seasonality were observed for temperature. River level, turbine discharge and spillway discharge, although they showed no clear seasonal dynamics, were time-dependent, because the autocorrelation coefficients for different k values were significant. In the samples of larger-sized fish, 23 species were recorded during the two years of study. Most of the individuals were in a non reproductive state, and about 90% of the individuals belonged to only six species. The temporal variability in total abundance, considering all species, indicated a pattern of seasonal variation; high abundances occurred from October through February (75%) and in Pool A (61% of the 1343 individuals sampled). Low abundances were recorded during winter, with the correlogram of total density confirming this tendency. In the samples of smaller-sized species, six species were recorded, with all six present in both pools, but more frequent in the first pool (64%). Bryconamericus stramineus comprised 99% of the total numbers of

Domingo Rodrigues, Fernandez; Angelo Antonio, Agostinho; Luis Maurício, Bini; Luiz Carlos, Gomes.

31

Ladder Logic  

Science.gov (United States)

Created by Tony R. Kuphaldt, with help from contributor Roger Hollingsworth, this chapter of All About Circuit's fourth volume on Digital circuits describes the logic behind them. The chapter is divided into six sections: "Ladder" diagrams, Digital logic functions, Permissive and interlock circuits, Motor control circuits, Fail-safe design, and Programmable logic controllers. Each section has clear illustrations and a concise, bulleted review of what was covered at the end. There is also a link to the All About Circuits forums, where contributors and other visitors discuss the material presented. This is an excellent resource for educators in physics and electronic engineering classrooms to introduce lessons or units on digital circuits.

Kuphaldt, Tony R.

2008-07-17

32

Utah Teacher Evaluation Project: The Park City Career Ladder Design. Final Report: Secretary's Discretionary Program, Planning Grant to Develop Teacher Incentive Programs.  

Science.gov (United States)

The Park City School District (Utah) career ladder design provides a system in which teachers are positioned and paid according to successful performance and differentiation of responsibilities. It includes an evaluation system to differentiate among teachers. The career ladder design presents a number of innovations; for example, excellent…

Peterson, Ken; And Others

33

Design and test of the final ALICE SDD CARLOS end ladder board  

CERN Document Server

The paper presents the design and test of the final prototype of the CARLOS (Compression And Run Length Encoding Subsystem) end ladder board that is going to be used in the ALICE experiment at CERN. This board is able to compress data coming from one Silicon Drift Detector (SDD) front-end electronics and to send them towards the data concentrator card CARLOSrx in counting room via a 800 Mb/s optical link. The board design faces several constraints, mainly size (54x49 mm) and radiation tolerance: for this reason the board contains several CERN developed ASICs. A test setup has been realized for selecting the good devices among the 500 cards already produced.

Antinori, S; Falchieri, D; Gabrielli, A; Gandolfi, E; Masetti, M; Tosellob, F

2007-01-01

34

Theoretical Design of a 104 MHz Ladder Type IH-RFQ Accelerator  

International Nuclear Information System (INIS)

Beam dynamics and rf designs of a 104 MHz ladder type IH-RFQ (L-IH-RFQ) accelerator are finished at Peking University for the acceleration of 14C+ from 40keV to 500keV. As a specific feature, the output beam energy spread is as low as 0.6% achieved with the internal discrete bunching method, which makes potential applications of RFQ feasible, such as accelerator mass spectrometry and ion implantation. Tolerances of the beam dynamics design are studied by means of changing the input beam parameters, and the results are quite satisfying. On the other hand, the L-IH-RFQ structure is employed, taking advantage of its mechanical stability and the absence of inter-electrode voltage asymmetry. Radio-frequency properties are studied and optimized for reducing power loss with Microwave Studio (MWS). Tuning of the field flatness and frequency is investigated in principle. (nuclear physics)

35

Fish passage ladders from Canoas Complex - Paranapanema River: evaluation of genetic structure maintenance of Salminus brasiliensis (Teleostei: Characiformes  

Directory of Open Access Journals (Sweden)

Full Text Available The aim of this study, utilizing RAPD techniques, was to determine the genetic variability of Salminus brasiliensis groups collected at passage ladders of the hydroelectric plants (HEP Canoas I and Canoas II - Paranapanema River (Brazil, as well as to estimate the population structure through different parameters of genetic diversity. The data obtained allowed us to conclude that S. brasiliensis of the Canoas Complex has a moderate index of genetic variability ( > 42.00% when compared to that of other migratory fish species. All genetic diversity analyses (distance = 0.015 and genetic identity = 0.985, F ST =0.018, AMOVA were signs of low genetic differentiation, and they led to the clustering of S. brasiliensis from Canoas I and Canoas II. This suggests that the species is genetically structured as a single population. Some findings indicate that this population of S. brasiliensis comes from the Capivara Reservoir (Canoas I downstream, probably fed by the Tibagi and Cinzas Rivers. Literature data denote that after fish transposition by passage ladders of the Canoas Complex, the migratory species are not concluding the reproductive cycle. This mechanism, therefore, could be one more impact factor causing the depletion in downstream recruitment, which could in medium and long term be compromising the natural S. brasiliensis population in the middle Paranapanema River.O objetivo desse estudo, utilizando a técnica de RAPD, foi estimar a variabilidade genética de grupos de Salminus brasiliensis coletados nas escadas de transposição das hidroelétricas de Canoas I e Canoas II - rio Paranapanema (Brasil, bem como estimar a estrutura populacional através de diferentes parâmetros de diversidade genética. Os dados obtidos permitiram concluir que S. brasiliensis do Complexo Canoas tem um índice moderado de variabilidade genética ( > 42.00% quando comparado com valores de outras espécies de peixes migradoras. Todas as análises de diversidade genética (distância = 0,015 e identidade genética = 0,985, F ST =0,018, AMOVA foram indicativas de baixa diferenciação genética, e conduziram ao agrupamento de S. brasiliensis proveniente das escadas de transposição de Canoas I e Canoas II, sugerindo que essa espécie está geneticamente estruturada como uma única população. Alguns dados indicam que essa população de S. brasiliensis é proveniente do Reservatório de Capivara (jusante de Canoas I, provavelmente mantida pelos rios Tibagi e das Cinzas. Dados da literatura indicam que após a transposição das escadas para peixes do Complexo Canoas, as espécies migradoras não estão concluindo o ciclo reprodutivo, esse mecanismo, portanto, pode ser mais um fator de impacto causando a depleção no recrutamento a jusante o que pode a médio e longo prazo comprometer a diversidade genética da população de S. brasiliensis no médio rio Paranapanema.

Carla Martins Lopes

2007-01-01

36

Fish passage ladders from Canoas Complex - Paranapanema River: evaluation of genetic structure maintenance of Salminus brasiliensis (Teleostei: Characiformes)  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese O objetivo desse estudo, utilizando a técnica de RAPD, foi estimar a variabilidade genética de grupos de Salminus brasiliensis coletados nas escadas de transposição das hidroelétricas de Canoas I e Canoas II - rio Paranapanema (Brasil), bem como estimar a estrutura populacional através de diferentes [...] parâmetros de diversidade genética. Os dados obtidos permitiram concluir que S. brasiliensis do Complexo Canoas tem um índice moderado de variabilidade genética ( > 42.00%) quando comparado com valores de outras espécies de peixes migradoras. Todas as análises de diversidade genética (distância = 0,015 e identidade genética = 0,985, F ST =0,018, AMOVA) foram indicativas de baixa diferenciação genética, e conduziram ao agrupamento de S. brasiliensis proveniente das escadas de transposição de Canoas I e Canoas II, sugerindo que essa espécie está geneticamente estruturada como uma única população. Alguns dados indicam que essa população de S. brasiliensis é proveniente do Reservatório de Capivara (jusante de Canoas I), provavelmente mantida pelos rios Tibagi e das Cinzas. Dados da literatura indicam que após a transposição das escadas para peixes do Complexo Canoas, as espécies migradoras não estão concluindo o ciclo reprodutivo, esse mecanismo, portanto, pode ser mais um fator de impacto causando a depleção no recrutamento a jusante o que pode a médio e longo prazo comprometer a diversidade genética da população de S. brasiliensis no médio rio Paranapanema. Abstract in english The aim of this study, utilizing RAPD techniques, was to determine the genetic variability of Salminus brasiliensis groups collected at passage ladders of the hydroelectric plants (HEP) Canoas I and Canoas II - Paranapanema River (Brazil), as well as to estimate the population structure through diff [...] erent parameters of genetic diversity. The data obtained allowed us to conclude that S. brasiliensis of the Canoas Complex has a moderate index of genetic variability ( > 42.00%) when compared to that of other migratory fish species. All genetic diversity analyses (distance = 0.015 and genetic identity = 0.985, F ST =0.018, AMOVA) were signs of low genetic differentiation, and they led to the clustering of S. brasiliensis from Canoas I and Canoas II. This suggests that the species is genetically structured as a single population. Some findings indicate that this population of S. brasiliensis comes from the Capivara Reservoir (Canoas I downstream), probably fed by the Tibagi and Cinzas Rivers. Literature data denote that after fish transposition by passage ladders of the Canoas Complex, the migratory species are not concluding the reproductive cycle. This mechanism, therefore, could be one more impact factor causing the depletion in downstream recruitment, which could in medium and long term be compromising the natural S. brasiliensis population in the middle Paranapanema River.

Carla Martins, Lopes; Fernanda Simões de, Almeida; Mário Luís, Orsi; Sandro Geraldo de Castro, Britto; Rodolfo Nardez, Sirol; Leda Maria Koelblinger, Sodré.

37

Design and Implementation for Ladder Diagram in Hydropower Simulation System Based on All Paths Searching Algorithm  

Directory of Open Access Journals (Sweden)

Full Text Available An approach to design and implement the control function of LD (Ladder Diagram in the hydropower simulation system based on all paths searching algorithm is proposed in this paper. LD is widely used as a programming language for PLC (Programmable Logic Controller, but it doesn’t be executed automatically in the hydropower simulation system which is a software system, and there is no compiler or interpretation for LD in it. The approach in this paper is not only to present a graphical interface to design LD, but also implement its control function through transforming it to a corresponding undigraph, in which, all paths be-tween two vertexes (live wire and null line are searched by the proposed algorithm. An application example is presented to verify the validity of the algorithm and shows that the algorithm is correct and practicable. In addition, how to implement the control function based on object-oriented thought is introduced. The running time is shown at last, which proves that the system with the algorithm can meet the real-time request in the hydropower simulation system.

Chun-He SONG

2009-07-01

38

Fish passage ladders from Canoas Complex - Paranapanema River: evaluation of genetic structure maintenance of Salminus brasiliensis (Teleostei: Characiformes)  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study, utilizing RAPD techniques, was to determine the genetic variability of Salminus brasiliensis groups collected at passage ladders of the hydroelectric plants (HEP) Canoas I and Canoas II - Paranapanema River (Brazil), as well as to estimate the population structure through different parameters of genetic diversity. The data obtained allowed us to conclude that S. brasiliensis of the Canoas Complex has a moderate index of genetic variability ( > 42.00%) when compared to t...

Carla Martins Lopes; Fernanda Simões de Almeida; Mário Luís Orsi; Sandro Geraldo de Castro Britto; Rodolfo Nardez Sirol; Leda Maria Koelblinger Sodré

2007-01-01

39

Designing and constructing an 100 bp DNA Ladder by combining PCR and enzyme digestion methods  

Directory of Open Access Journals (Sweden)

Full Text Available "n Normal 0 false false false EN-US X-NONE AR-SA MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Arial; mso-bidi-theme-font:minor-bidi;} Background: Molecular DNA markers are one of the most important tools in molecular biology labs. The size of DNA molecules is determined by comparing them with known bands of markers during gel electrophoresis. There are many different protocols to produce these kinds of molecular markers. In this study we have suggested an efficient strategy to produce molecular weight markers in industrial proportions."n"nMethods : To achieve the desired sizes of DNA fragments, a combination of two previously known methods, restriction enzyme digestion and polymerase chain reaction (PCR, were used. The enzymatic digestion process was based on designing and constructing plasmids which equaled in size with the desired length of DNA fragments and produced the desired DNA fragment upon linearization. In the PCR method, the desired length of DNA fragments were cloned in multiple cloning sites of pTZ57R plasmid and in a PCR reaction, the new constructed plasmid was used as a template to produce the final fragment."n"nResults : Upon application of this strategy, 2000 and 3000 bp DNA fragments were produced by enzymatic digestion of plasmids of the same size. Moreover, 100 to 1500 bp fragments were produced during PCR using only a set of forward and reverse primers at the flanking region of pTZ57R multiple cloning site."n"nConclusion: The highest advantage of this cost-benefit approach is to produce different types of molecular weight markers by using an effective and short protocol."n"nKeywords: DNA markers, DNA Ladder, agarose gel electrophoresis, molecular weight.

Saidijam M

2011-05-01

40

The potential for a fish ladder to mitigate against the loss of marine-estuarine-freshwater connectivity in a subtropical coastal lake  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english Increasing water demand in coastal regions has resulted in the construction of weirs and barrages in coastal freshwaters. These form barriers to migrations of estuarine and euryhaline marine fishes and crustaceans. This study assessed the impact of loss of marine-estuarine-freshwater connectivity ca [...] used by a weir at the outlet of Lake Mzingazi, a coastal lake on the subtropical east coast of South Africa. Facultative catadromous estuarine and euryhaline marine fishes were most affected by the weir, which blocked their upstream migration. These fishes were absent in the lake and were prevented from accessing potential nursery habitat. Crustaceans were less affected by the outlet weir. Salinity tolerances of most penaeid prawn species occurring in southern African estuaries prevent penetration into freshwater reaches of connected systems. Movements of palaemonid prawns which either spawn in or have larvae dependant on estuarine water, and the marine spawning brachyuran Varuna litterata, were not completely impeded by the weir. These species have larvae and juveniles that can climb over the weir in its present form. Historically, the lake served as an estuarine nursery and its physico-chemistry and habitats still offer viable and valuable habitat to estuarine species. There is therefore great potential value in installing a fish ladder at the lake outlet that can be used by juvenile fishes and crustaceans. Re-establishing marine-estuarine-freshwater connectivity here will reinstate a natural migration route that has been impeded for over 70 years and partially restore the ecosystem to its original state

SP, Weerts; CF, MacKay; DP, Cyrus.

2014-01-01

 
 
 
 
41

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...considerations. All ladders, appurtenances, and fastenings shall be designed to meet the following...considered in the design of rails and fastenings. (2) Design stresses. Design...edges, splinters, or burrs. (3) Fastenings. Fastenings shall be an...

2010-07-01

42

Design of heterothermic muscle in fish.  

Science.gov (United States)

Among the tremendous diversity of fish, there are a small number that are considered elite in their swimming performance. These include representatives from the tunas, billfish and sharks. In addition to being elite swimmers, these fish share numerous specialized anatomical features including the structure of their swimming muscles and some form of regional endothermy, termed heterothermy. These heterothermies fall into two classes: those that maintain elevated temperatures in swimming muscles and those that have muscle-derived tissues specialized for delivering warm blood to the brain. Because these versions of heterothermy are manifest in fish whose swimming performance is considered elite, it has been parsimonious to hypothesize that heterothermy is part of an integrated high-performance design. Recognizing that the design of skeletal muscle is hierarchical, the design of heterothermic muscle in fish will be examined within a hierarchical framework. This paper will examine, in order, the specific anatomical specializations, the performance of muscle as a biomaterial and then as a dynamic mechanical structure or device - in each case looking at the extent to which heterothermy is part of an integrated high-performance design or is perhaps just a happy accident. This examination will reveal how difficult it is to make a case for the central importance of heterothermy in the design of these swimming muscle systems. PMID:12110659

Katz, Stephen L

2002-08-01

43

Hood River and Pelton Ladder Monitoring and Evaluation Project and Hood River Fish Habitat Project : Annual Progress Report 1999-2000.  

Energy Technology Data Exchange (ETDEWEB)

The Hood River subbasin is home to four species of anadromous salmonids: chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), steelhead (Oncorhynchus mykiss), and sea run cutthroat trout (Salmo clarki). Indigenous spring chinook salmon were extirpated during the late 1960's. The naturally spawning spring chinook salmon currently present in the subbasin are progeny of Deschutes stock. Historically, the Hood River subbasin hatchery steelhead program utilized out-of-basin stocks for many years. Indigenous stocks of summer and winter steelhead were listed in March 1998 by National Marine Fisheries Service (NMFS) under the Endangered Species Act (ESA) as a ''Threatened'' Species along with similar genetically similar steelhead in the Lower Columbia Basin. This annual report summarizes work for two consecutive contract periods: the fiscal year (FY) 1999 contract period was 1 October, 1998 through 30 September, 1999 and 1 October, 1999 through 30 September, 2000 for FY 2000. Work implemented during FY 1999 and FY 2000 included (1) acclimation of hatchery spring chinook salmon and hatchery summer and winter steelhead smolts, (2) spring chinook salmon spawning ground surveys on the West Fork Hood River (3) genetic analysis of steelhead and cutthroat [contractual service with the ODFW], (4) Hood River water temperature studies, (5) Oak Springs Hatchery (OSH) and Round Butte Hatchery (RBH) coded-wire tagging and clipping evaluation, (6) preparation of the Hood River Watershed Assessment (Coccoli et al., December 1999) and the Fish Habitat Protection, Restoration, and Monitoring Plan (Coccoli et al., February 2000), (7) project implementation of early action habitat protection and restoration projects, (8) Pelton Ladder evaluation studies, (9) management oversight and guidance to BPA and ODFW engineering on HRPP facilities, and (10) preparation of an annual report summarizing project objectives for FY 1999 and FY 2000.

Lambert, Michael B.; McCanna, Joseph P.; Jennings, Mick

2001-02-01

44

Hood River and Pelton Ladder monitoring and evaluation project and Hood River fish habitat project : annual progress report 1999-2000.; ANNUAL  

International Nuclear Information System (INIS)

The Hood River subbasin is home to four species of anadromous salmonids: chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), steelhead (Oncorhynchus mykiss), and sea run cutthroat trout (Salmo clarki). Indigenous spring chinook salmon were extirpated during the late 1960's. The naturally spawning spring chinook salmon currently present in the subbasin are progeny of Deschutes stock. Historically, the Hood River subbasin hatchery steelhead program utilized out-of-basin stocks for many years. Indigenous stocks of summer and winter steelhead were listed in March 1998 by National Marine Fisheries Service (NMFS) under the Endangered Species Act (ESA) as a ''Threatened'' Species along with similar genetically similar steelhead in the Lower Columbia Basin. This annual report summarizes work for two consecutive contract periods: the fiscal year (FY) 1999 contract period was 1 October, 1998 through 30 September, 1999 and 1 October, 1999 through 30 September, 2000 for FY 2000. Work implemented during FY 1999 and FY 2000 included (1) acclimation of hatchery spring chinook salmon and hatchery summer and winter steelhead smolts, (2) spring chinook salmon spawning ground surveys on the West Fork Hood River (3) genetic analysis of steelhead and cutthroat[contractual service with the ODFW], (4) Hood River water temperature studies, (5) Oak Springs Hatchery (OSH) and Round Butte Hatchery (RBH) coded-wire tagging and clipping evaluation, (6) preparation of thclipping evaluation, (6) preparation of the Hood River Watershed Assessment (Coccoli et al., December 1999) and the Fish Habitat Protection, Restoration, and Monitoring Plan (Coccoli et al., February 2000), (7) project implementation of early action habitat protection and restoration projects, (8) Pelton Ladder evaluation studies, (9) management oversight and guidance to BPA and ODFW engineering on HRPP facilities, and (10) preparation of an annual report summarizing project objectives for FY 1999 and FY 2000

45

The Design and Implementation of a Biomimetic Robot Fish  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, a novel design of a biomimetic robot fish is presented. Based on the propulsion and maneuvering mechanisms of real fishes, a tail mechanical structure with cams and connecting rods for fitting carangiform fish body wave is designed, which provides the main propulsion. Two pectoral fins are mounted, and each pectoral fin can flap separately and rotate freely. Coordinating the movements of the tail and pectoral fins, the robot fish can simulate the movements of fishes in water. I...

Chao Zhou; Min Tan; Nong Gu; Zhiqiang Cao; Shuo Wang; Long Wang

2008-01-01

46

Ladder/PLC's  

Science.gov (United States)

This is a webpage with many learning objects on Ladder/PLC's with over 15 lessons in: Basic PLC Software Programming, Relay Ladder Logic, Advanced PLC Software Programming and PLC Hardware/Addressing. Each lesson links to an interactive resource which helps to further illustrate the concepts related.

2012-12-28

47

Design of a single flux quantum {sigma}-{delta} A/D converter with a ladder circuit as an on-chip-clock-generating circuit  

Energy Technology Data Exchange (ETDEWEB)

We investigated an oversampling {sigma}-{delta} A/D converter (ADC) with a large signal-to-noise ratio ({approx}80 dB or more) and a wide bandwidth ({approx}100 MHz), which were formed from single flux quantum circuits. The ADC consisted of a second-order lowpass {sigma}-{delta} modulator and a third-order sinc decimation filter. A ladder circuit was utilized to supply the high frequency sampling clock signal of more than 16 GHz to the modulator. The third-order sinc filter was designed from a multistage decimation sinc filter and a multiple integration sinc filter. By combining both sinc filters, the sinc filter operating with a decimation factor of 16 at the high clock frequency of more than 16 GHz could be designed in the chip area of {approx}10 x 10 mm{sup 2}. Experimentally, we measured the bit rate of the ladder circuit from an average voltage measurement and an oscilloscope observation, and obtained the bit rate of 31 Gbps.

Hasegawa, H.; Hirano, S.; Nagasawa, S.; Miyahara, K.; Enomoto, Y

2003-10-15

48

Fish passage system in an irrigation dam (Pilcomayo River basin : when engineering designs do not match ecohydraulic criteria  

Directory of Open Access Journals (Sweden)

Full Text Available The Route 28 Dam has the potential to block fish movements from La Estrella marsh to the Pilcomayo River. In addition, the many fish that concentrate immediately downstream of the dam may suffer high mortality when they are stranded during low water periods. The goals of this study are to determine if fish are able to pass the spillway and to assess if the design of the installed ladders (pool and weir type effectively supports upstream migration of Prochilodus lineatus (sábalo. Results showed that only fish longer than 39 cm should be able to ascend the spillway chute, but when water levels on the spillway crest are over 0.4 m. Fish are also unable to jump from spillway toe to spillway crest because the downstream dissipation pool does not meet the minimum depth criterion for fish to accelerate to sufficient velocity. Fish ladders have insufficient number of pools and some pool dimensions and designs depart from accepted standard designs. Volumetric dissipation power in the upper pool of each fish ladder is too low for fish to rest. Also, attraction flows relative to total spillway discharge at the entrance to each fishway are insufficient. Fish passage failures of both the spillway and pool and weir systems in La Estrella marsh can be traced to the "salmon-centric" concept used by the designers. We conclude that the Route 28 Dam design including its fish passage systems, do not follow criteria to cope with the strong hydrological variability and bioecological characteristics of fish inhabiting pulsatile systems such as La Estrella marsh.La represa dela ruta 28 posee el potencial de bloquear el desplazamiento del sábalo (Prochilodus lineatus desde el bañado La Estrella hacia el río Pilcomayo. Adicionalmente los numerosos peces que se concentran aguas abajo de la represa pueden sufrir una alta mortalidad cuando quedan atrapados durante el período de aguas bajas. Los objetivos de este estudio es determinar si los peces son capaces de superar el vertedero y evaluar si el diseño de los pasos para peces del tipo tanque-escalón ya instalados esadecuado para facilitar la migración hacia aguas arriba. Los resultados muestran que solo aquellos peces mayores a 39 cm de longitud total son capaces de ascender la pendiente del vertedero, pero únicamente cuando el nivel del agua en la cresta del mismo alcanza o supera los 40 cm. Los peces son incapaces de saltar desde el pie del vertedero hasta la cresta debido a que la pileta de disipación no sigue los criterios de mínima profundidad requeridos para alcanzar la suficiente velocidad y altura. Asimismo, los pasos para peces no poseen el número suficiente de tanques y algunas de sus dimensiones y su diseño se apartan de los estándares aceptados. La potencia de disipación volumétrica en el tanque superior de cada paso es inadecuada para que los peces puedan descansar, mientras que los flujos de atracción relativos a la descarga del vertedero resultan insuficientes. La baja eficiencia del vertedero y de los sistemas de pasos para peces pueden ser adjudicados a un concepto de construcción orientado a salmónidos. Concluimos que la represa de la ruta 28, incluyendo sus sistemas de pasaje para peces, no siguen los criterios adecuados para hacer frente a alta variabilidad hidrológica y las características bioecológica de los peces que habitan en bañados pulsátiles como La Estrella.

Claudio R. M. Baigún

2012-10-01

49

Fish passage system in an irrigation dam (Pilcomayo River basin ): when engineering designs do not match ecohydraulic criteria  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in spanish La represa dela ruta 28 posee el potencial de bloquear el desplazamiento del sábalo (Prochilodus lineatus) desde el bañado La Estrella hacia el río Pilcomayo. Adicionalmente los numerosos peces que se concentran aguas abajo de la represa pueden sufrir una alta mortalidad cuando quedan atrapados dura [...] nte el período de aguas bajas. Los objetivos de este estudio es determinar si los peces son capaces de superar el vertedero y evaluar si el diseño de los pasos para peces del tipo tanque-escalón ya instalados esadecuado para facilitar la migración hacia aguas arriba. Los resultados muestran que solo aquellos peces mayores a 39 cm de longitud total son capaces de ascender la pendiente del vertedero, pero únicamente cuando el nivel del agua en la cresta del mismo alcanza o supera los 40 cm. Los peces son incapaces de saltar desde el pie del vertedero hasta la cresta debido a que la pileta de disipación no sigue los criterios de mínima profundidad requeridos para alcanzar la suficiente velocidad y altura. Asimismo, los pasos para peces no poseen el número suficiente de tanques y algunas de sus dimensiones y su diseño se apartan de los estándares aceptados. La potencia de disipación volumétrica en el tanque superior de cada paso es inadecuada para que los peces puedan descansar, mientras que los flujos de atracción relativos a la descarga del vertedero resultan insuficientes. La baja eficiencia del vertedero y de los sistemas de pasos para peces pueden ser adjudicados a un concepto de construcción orientado a salmónidos. Concluimos que la represa de la ruta 28, incluyendo sus sistemas de pasaje para peces, no siguen los criterios adecuados para hacer frente a alta variabilidad hidrológica y las características bioecológica de los peces que habitan en bañados pulsátiles como La Estrella. Abstract in english The Route 28 Dam has the potential to block fish movements from La Estrella marsh to the Pilcomayo River. In addition, the many fish that concentrate immediately downstream of the dam may suffer high mortality when they are stranded during low water periods. The goals of this study are to determine [...] if fish are able to pass the spillway and to assess if the design of the installed ladders (pool and weir type) effectively supports upstream migration of Prochilodus lineatus (sábalo). Results showed that only fish longer than 39 cm should be able to ascend the spillway chute, but when water levels on the spillway crest are over 0.4 m. Fish are also unable to jump from spillway toe to spillway crest because the downstream dissipation pool does not meet the minimum depth criterion for fish to accelerate to sufficient velocity. Fish ladders have insufficient number of pools and some pool dimensions and designs depart from accepted standard designs. Volumetric dissipation power in the upper pool of each fish ladder is too low for fish to rest. Also, attraction flows relative to total spillway discharge at the entrance to each fishway are insufficient. Fish passage failures of both the spillway and pool and weir systems in La Estrella marsh can be traced to the "salmon-centric" concept used by the designers. We conclude that the Route 28 Dam design including its fish passage systems, do not follow criteria to cope with the strong hydrological variability and bioecological characteristics of fish inhabiting pulsatile systems such as La Estrella marsh.

Claudio R. M., Baigún; John M., Nestler; Priscilla, Minotti; Norberto, Oldani.

50

Fish passage system in an irrigation dam (Pilcomayo River basin ): when engineering designs do not match ecohydraulic criteria  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in spanish La represa dela ruta 28 posee el potencial de bloquear el desplazamiento del sábalo (Prochilodus lineatus) desde el bañado La Estrella hacia el río Pilcomayo. Adicionalmente los numerosos peces que se concentran aguas abajo de la represa pueden sufrir una alta mortalidad cuando quedan atrapados dura [...] nte el período de aguas bajas. Los objetivos de este estudio es determinar si los peces son capaces de superar el vertedero y evaluar si el diseño de los pasos para peces del tipo tanque-escalón ya instalados esadecuado para facilitar la migración hacia aguas arriba. Los resultados muestran que solo aquellos peces mayores a 39 cm de longitud total son capaces de ascender la pendiente del vertedero, pero únicamente cuando el nivel del agua en la cresta del mismo alcanza o supera los 40 cm. Los peces son incapaces de saltar desde el pie del vertedero hasta la cresta debido a que la pileta de disipación no sigue los criterios de mínima profundidad requeridos para alcanzar la suficiente velocidad y altura. Asimismo, los pasos para peces no poseen el número suficiente de tanques y algunas de sus dimensiones y su diseño se apartan de los estándares aceptados. La potencia de disipación volumétrica en el tanque superior de cada paso es inadecuada para que los peces puedan descansar, mientras que los flujos de atracción relativos a la descarga del vertedero resultan insuficientes. La baja eficiencia del vertedero y de los sistemas de pasos para peces pueden ser adjudicados a un concepto de construcción orientado a salmónidos. Concluimos que la represa de la ruta 28, incluyendo sus sistemas de pasaje para peces, no siguen los criterios adecuados para hacer frente a alta variabilidad hidrológica y las características bioecológica de los peces que habitan en bañados pulsátiles como La Estrella. Abstract in english The Route 28 Dam has the potential to block fish movements from La Estrella marsh to the Pilcomayo River. In addition, the many fish that concentrate immediately downstream of the dam may suffer high mortality when they are stranded during low water periods. The goals of this study are to determine [...] if fish are able to pass the spillway and to assess if the design of the installed ladders (pool and weir type) effectively supports upstream migration of Prochilodus lineatus (sábalo). Results showed that only fish longer than 39 cm should be able to ascend the spillway chute, but when water levels on the spillway crest are over 0.4 m. Fish are also unable to jump from spillway toe to spillway crest because the downstream dissipation pool does not meet the minimum depth criterion for fish to accelerate to sufficient velocity. Fish ladders have insufficient number of pools and some pool dimensions and designs depart from accepted standard designs. Volumetric dissipation power in the upper pool of each fish ladder is too low for fish to rest. Also, attraction flows relative to total spillway discharge at the entrance to each fishway are insufficient. Fish passage failures of both the spillway and pool and weir systems in La Estrella marsh can be traced to the "salmon-centric" concept used by the designers. We conclude that the Route 28 Dam design including its fish passage systems, do not follow criteria to cope with the strong hydrological variability and bioecological characteristics of fish inhabiting pulsatile systems such as La Estrella marsh.

Claudio R. M., Baigún; John M., Nestler; Priscilla, Minotti; Norberto, Oldani.

2012-10-01

51

The eel ladders of the double slot pass Geesthacht; Aalleitern am Doppelschlitzpass Geesthacht  

Energy Technology Data Exchange (ETDEWEB)

To facilitate the upstream migration of glass eels, four eel ladders were installed within and next to the fish pass at the Geesthacht dam. Similar to other fish pass construction types it was necessary to ensure that the ladders could be both detected and passed by the juvenile eels. A custom built monitoring station will be used to guarantee the correct functioning of the eel ladders and subsequently document the eel migration from the beginning of the next season. (orig.)

Adam, Beate [Institut fuer angewandte Oekologie, Kirtorf-Wahlen (Germany); Neumann, Christof [Knabe Enders Duehrkop Ingenieure GmbH, Hamburg (Germany)

2012-07-01

52

Investigations of the thermal properties of the LHCb Inner Tracker silicon ladders by finite element analysis  

CERN Document Server

This note reports about the thermal performance of silicon ladder designs which are being proposed for the LHCb Inner Tracker. The heat characteristics for different silicon ladder design options are evaluated by using the finite element analysis program package ANSYS. The thermal performance of the silicon ladder after 10 years of operation in the LHCb radiation environment is investigated.

Blocki, J

2001-01-01

53

The Design and Implementation of a Biomimetic Robot Fish  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, a novel design of a biomimetic robot fish is presented. Based on the propulsion and maneuvering mechanisms of real fishes, a tail mechanical structure with cams and connecting rods for fitting carangiform fish body wave is designed, which provides the main propulsion. Two pectoral fins are mounted, and each pectoral fin can flap separately and rotate freely. Coordinating the movements of the tail and pectoral fins, the robot fish can simulate the movements of fishes in water. In order to obtain the necessary environmental information, several kinds of sensors (video, infrared, temperature, pressure and PH value sensors were mounted. Finally, the realization of the robot fish is presented.

Chao Zhou

2008-11-01

54

Deflector designs for fish habitat restoration.  

Science.gov (United States)

Paired current deflectors are structures that are installed on each bank of a river to locally reduce the width of the channel, thereby creating flow acceleration and promoting scouring. These instream habitat structures have been used extensively in restoration projects to create pool habitat for fish, but there are many discrepancies in deflector design recommendations in terms of orientation, height, and length. Our objectives were to (1) examine how the angle, height, and length of paired deflectors affect scour hole dimensions and potential for bank erosion; and (2) test the applicability to paired deflectors of existing equations for scour hole depth and volume. Three deflector angles (45 degrees, 90 degrees, and 135 degrees), two deflector heights (with flow under and over the deflector height), and two lengths (reducing the width by 25% and 50%) were investigated using uniform sand in a laboratory flume. Results showed a 26-30% smaller scour depth resulting from 45 degrees deflectors than from 90 degrees deflectors and a 5-10% smaller scour depth for 135 degrees deflectors compared to 90 degrees deflectors. The volume of scour and the potential for bank erosion were greater when flow was under the height of the deflectors rather than overtopping and when the length of deflector was increased. When flow was under the deflector height, 135 degrees deflectors had the highest amount of bank erosion; whereas during overtopping flow conditions, 90 degrees deflectors had the greatest bank erosion potential. Values predicted by the model of Kuhnle and others were closest to observed scour depth and volume measurements. The assumption that upstream-oriented deflectors always generate the largest scour should be revised. PMID:14994157

Biron, Pascale M; Robson, Colleen; Lapointe, Michel F; Gaskin, Susan J

2004-01-01

55

Baryons and ladders  

International Nuclear Information System (INIS)

By formal manipulation of the QCD functional integral we arrive at a relativistic low energy effective theory of non-local color singlet mesons and baryons, which at tree level sums up ladders of effective glue exchange between constituent quarks. (orig.)

56

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...must be at least equivalent in strength to a one-piece side rail...the carrier, to provide the strength necessary to stop employees...shall not reduce the design strength of the ladder. (24...limited to, flat metal or concrete surfaces that are...

2010-07-01

57

Design of a re-entrant double-staggered ladder circuit for V-band coupled-cavity traveling-wave tubes  

International Nuclear Information System (INIS)

The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, as well as easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling-wave tube is constructed. The electromagnetic characteristics and the beam—wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

58

Bioinspiration from fish for smart material design and function  

International Nuclear Information System (INIS)

Fish are a potentially rich source of inspiration for the design of smart materials. Fish exemplify the use of flexible materials to generate forces during locomotion, and a hallmark of fish functional design is the use of body and fin deformation to power propulsion and maneuvering. As a result of nearly 500 million years of evolutionary experimentation, fish design has a number of interesting features of note to materials engineers. In this paper we first provide a brief general overview of some key features of the mechanical design of fish, and then focus on two key properties of fish: the bilaminar mechanical design of bony fish fin rays that allows active muscular control of curvature, and the role of body flexibility in propulsion. After describing the anatomy of bony fish fin rays, we provide new data on their mechanical properties. Three-point bending tests and measurement of force inputs to and outputs from the fin rays show that these fin rays are effective displacement transducers. Fin rays in different regions of the fin differ considerably in their material properties, and in the curvature produced by displacement of one of the two fin ray halves. The mean modulus for the proximal (basal) region of the fin rays was 1.34 GPa, but this varied from 0.24 to 3.7 GPa for different fin rays. The distal fin region was less stiff, and moduli for the different fin rays measured varied from 0.11 to 0.67 GPa. These data are similar to those for human tendons (modulusimilar to those for human tendons (modulus around 0.5 GPa). Analysis of propulsion using flexible foils controlled using a robotic flapping device allows investigation of the effect of altering flexural stiffness on swimming speed. Flexible foils with the leading edge moved in a heave show a distinct peak in propulsive performance, while the addition of pitch input produces a broad plateau where the swimming speed is relatively unaffected by the flexural stiffness. Our understanding of the material design of fish and the control of tissue stiffness is still in its infancy, and the development of smart materials to assist in investigating the active control of stiffness and in the construction of robotic fish-like devices is a key challenge for the near future

59

FPGA Implementations of Ladder Diagrams  

Directory of Open Access Journals (Sweden)

Full Text Available The performance of programmable logic controllers is often constrained by the microprocessor and the real-time firmware of the controller. Field programmable gate arrays (FPGAs are an attractive potential implementation medium for high-speed control because of their fast and parallel execution and programmable nature. Ladder Diagrams are a standard graphical programming method for industrial controllers, but compilers from Ladder Diagrams to FPGA hardware do not yet exist. This paper explores the comparative speed of four different classes of FGPA implementation of Ladder Diagrams - Interpreted Software, Compiled Software, Interpreted Hardware and Compiled Hardware. It also explores parallel versus serial execution of Ladder Diagrams in hardware, and identifies timers as a major resource user in parallel implementations. Overall, a Shared Timer Serial Compiled Hardware system for FPGA implementation of Ladder Diagrams is recommended. Using comparable FPGA resources to other alternatives it provides a 20-600 times speed improvement over other solutions whilst maintaining correct Ladder Diagram semantics.

Neil William Bergmann

2013-02-01

60

Improved intake design for downstream migrating fish at hydropower plants  

International Nuclear Information System (INIS)

This paper reports on hydroelectric power projects on the Columbia River which provided low-cost electricity to the Pacific Northwest. However, they are detrimental to anadromous fisheries resources. Anadromous fish are migratory. They begin their life in shallow mountain streams. After several months, they migrate to the ocean, where the fish grow to maturity before their return migration. Remarkably, most anadromous fish return to spawn in their natal streams. At dams, the upstream migration of grown salmon and steelhead is accomplished through fishways. The downstream migration of juveniles remains a serious problem. Juvenile fish follow the water flow during their sea-ward migration. When passing through a turbine, fish can be severely injured due to the sudden pressure drop, high velocity shear zones, and rotating turbine blades. Stunned fish that survive the gauntlet of the turbine are easy prey for sea gulls and squawfish in the tailrace of the powerhouse. Fish mortality per turbine passage is estimated at 15 percent. With nine hydropower projected on the main steam of the Columbia River, their combined mortality is very serious. The historical Columbia River anadromous run of about 12 million fish has declined to 2.5 million in recent years. Modern high-output hydraulic turbines are designed to be placed at a lower elevation to minimize cavitation damage to turbine blades. The modern design trend of deep intake submergence has caused parallel and unsteady vortex flow patterns in the forebay, resulting in a decrease in the guiding efficiency of the screens, such as at Bonneville Second Powerhouse and at Rocky Reach Project

 
 
 
 
61

Six-Degree-of-Freedom Sensor Fish Design and Instrumentation  

Directory of Open Access Journals (Sweden)

Full Text Available Fish passing through dams may be injured or killed despite advances in turbinedesign, project operations and other fish bypass systems. The six-degree-of-freedom (6DOFSensor Fish device is an autonomous sensor package that characterizes the physical conditionsand physical stresses to which fish are exposed when they pass through complex hydraulicenvironments. It has been used to identify the locations and operations where conditions aresevere enough to injure or kill fish. During the design process, a set of governing equationsof motion for the Sensor Fish was derived and simulated to understand the design implica-tions of instrument selection and placement within the body of the device. The Sensor Fishpackage includes three rotation sensors, three acceleration sensors, a pressure sensor, and atemperature sensor with a sampling frequency of 2,000 Hz. Its housing is constructed of clearpolycarbonate plastic. It is 24.5 mm in diameter and 90 mm in length and weighs about 43 g,similar to the size and density of a yearling salmon smolt. The accuracy of the pressure sensorwas determined to be within 0.2 psi. In laboratory acceptance tests, the relative errors of boththe linear acceleration and angular velocity measurements were determined to be less than5%. An exposure is defined as a significant event when the acceleration reaches predefinedthresholds. Based on the different characteristic of acceleration and rotation velocities, theexposure event is categorized as either a collision between the Sensor Fish and a solid struc-ture or shear caused by turbulence. Since its development in 2005, the 6DOF Sensor Fish hasbeen deployed successfully at many major dams in the United States.

Marshall C. Richmond

2007-11-01

62

29 CFR 1917.119 - Portable ladders.  

Science.gov (United States)

...side rails; (iii) Missing or loose bolts, rivets or fastenings; (iv) Defective ropes; or (v) Any other structural...the ladder. (f) Ladder usage. (1) Ladders made by fastening rungs or devices across a single rail are prohibited....

2010-07-01

63

Fish swarm optimization algorithm applied to engineering system design  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Nowadays, optimization techniques based on the analogy with swarming principles and collective activities of social species in nature have been used in the development of methodologies for solving a variety of real-world optimization problems. In this context, the social behavior of fish colonies ha [...] s been recently explored to develop a novel algorithm, the so-called Fish Swarm Optimization Algorithm (FSOA), based on the behavior of fish swarm in search for food. In this paper, the FSOA is applied to four engineering systems, involving typical structural design and distillation column design. The results obtained are then compared with those obtained from other classical evolutionary approaches.

Fran Sérgio, Lobato; Valder, Steffen Jr..

64

Fish swarm optimization algorithm applied to engineering system design  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Nowadays, optimization techniques based on the analogy with swarming principles and collective activities of social species in nature have been used in the development of methodologies for solving a variety of real-world optimization problems. In this context, the social behavior of fish colonies ha [...] s been recently explored to develop a novel algorithm, the so-called Fish Swarm Optimization Algorithm (FSOA), based on the behavior of fish swarm in search for food. In this paper, the FSOA is applied to four engineering systems, involving typical structural design and distillation column design. The results obtained are then compared with those obtained from other classical evolutionary approaches.

Fran Sérgio, Lobato; Valder, Steffen Jr..

2014-01-01

65

Design and construction of Eicher penstock fish screens  

International Nuclear Information System (INIS)

A penstock screen design, patented by George Eicher, was developed to accomodate site conditions at the Puntledge Dam. The screen removes juvenile and anadromous fish from the power flow and returns them to the river downstream of the dam. Hydraulic modelling at 1:10.96 scale was carried out to determine the optimum location and design of the screen, and a screen location 3 diameters downstream of the intakes was chosen. A standard Johnson stainless steel wedgewire screen with a uniform porosity of 58% was chosen. The screens are cleaned by rotating them about a horizontal trunnion at their midpoint. Total cost of the project was $4,750,000. Turbine mortality, which was greater than 60% of annual migration, was eliminated. Mortality through the screen and bypass facility is less than 1%. Details are presented of the design of the screens, fish bypass pipes and evaluation facility. 2 refs., 1 fig

66

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...provided with cages, wells, ladder safety devices...or (iii) A cage or well, and multiple ladder...individual-rung ladders; (ii) Vertical bars shall be on the...vertically; (vi) Vertical bars shall be spaced...of access. (21) Wells for fixed ladders...

2010-07-01

67

Integral representations combining ladders and crossed-ladders  

CERN Document Server

We use the worldline formalism to derive integral representations for three classes of amplitudes in scalar field theory: (i) the scalar propagator exchanging N momenta with a scalar background field (ii) the "half-ladder" with N rungs in x - space (iii) the four-point ladder with N rungs in x - space as well as in (off-shell) momentum space. In each case we give a compact expression combining the N! Feynman diagrams contributing to the amplitude. As our main application, we reconsider the well-known case of two massive scalars interacting through the exchange of a massless scalar. Applying asymptotic estimates and a saddle-point approximation to the N-rung ladder plus crossed ladder diagrams, we derive a semi-analytic approximation formula for the lowest bound state mass in this model.

Bastianelli, F; Schubert, C; Thakur, R; Weber, A

2014-01-01

68

Integral representations combining ladders and crossed-ladders  

Science.gov (United States)

We use the worldline formalism to derive integral representations for three classes of amplitudes in scalar field theory: (i) the scalar propagator exchanging N momenta with a scalar background field (ii) the "half-ladder" with N rungs in x-space (iii) the four-point ladder with N rungs in x-space as well as in (off-shell) momentum space. In each case we give a compact expression combining the N! Feynman diagrams contributing to the amplitude. As our main application, we reconsider the well-known case of two massive scalars interacting through the exchange of a massless scalar. Applying asymptotic estimates and a saddle-point approximation to the N-rung ladder plus crossed ladder diagrams, we derive a semi-analytic approximation formula for the lowest bound state mass in this model.

Bastianelli, F.; Huet, A.; Schubert, C.; Thakur, R.; Weber, A.

2014-07-01

69

Bending continuous structures with SMAs: a novel robotic fish design.  

Science.gov (United States)

In this paper, we describe our research on bio-inspired locomotion systems using deformable structures and smart materials, concretely shape memory alloys (SMAs). These types of materials allow us to explore the possibility of building motor-less and gear-less robots. A swimming underwater fish-like robot has been developed whose movements are generated using SMAs. These actuators are suitable for bending the continuous backbone of the fish, which in turn causes a change in the curvature of the body. This type of structural arrangement is inspired by fish red muscles, which are mainly recruited during steady swimming for the bending of a flexible but nearly incompressible structure such as the fishbone. This paper reviews the design process of these bio-inspired structures, from the motivations and physiological inspiration to the mechatronics design, control and simulations, leading to actual experimental trials and results. The focus of this work is to present the mechanisms by which standard swimming patterns can be reproduced with the proposed design. Moreover, the performance of the SMA-based actuators' control in terms of actuation speed and position accuracy is also addressed. PMID:22126900

Rossi, C; Colorado, J; Coral, W; Barrientos, A

2011-12-01

70

A Child Care Career Ladder  

Science.gov (United States)

A child care agency has developed a career ladder to make the child care position more attractive to young people. As another step toward professionalization of the child care field, it could serve as a model for other agencies. (GO)

Stevens, George T.; Mueller, Carl

1976-01-01

71

Can fishing gear protect non-target fish? Design and evaluation of bycatch reduction technology for commercial fisheries  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The impacts of commercial fishing extend far beyond direct effects on targeted species. As much as 40% of global marine catch is attributable to bycatch, or the capture of non-target organisms which occurs during fishing. The amount of bycatch in a fishery is determined in part by the selectivity of the industry’s fishing gear, and bycatch mitigation often focuses on improving the selectivity of these gears. This thesis explores bycatch mitigation through the design and evaluation of bycatc...

Favaro, Brett

2013-01-01

72

Fish  

Science.gov (United States)

In this project you will learn about different types of fish. In your science journal write what you know about fish. Draw a picture of a common fish you might see where you live. On the handout record the information you learn during this unit. Click here to see the Angel Fish. Record information on Handout #1. Now go to the Clown Fish. ...

Hunter, Ms.

2009-07-07

73

Can Fish Morphological Characteristics be Used to Re-design Hydroelectric Turbines?  

Energy Technology Data Exchange (ETDEWEB)

Safe fish passage affects not only migratory species, but also populations of resident fish by altering biomass, biodiversity, and gene flow. Consequently, it is important to estimate turbine passage survival of a wide range of susceptible fish. Although fish-friendly turbines show promise for reducing turbine passage mortality, experimental data on their beneficial effects are limited to only a few species, mainly salmon and trout. For thousands of untested species and sizes of fish, the particular causes of turbine passage mortality and the benefits of fish-friendly turbine designs remain unknown. It is not feasible to measure the turbine-passage survival of every species of fish in every hydroelectric turbine design. We are attempting to predict fish mortality based on an improved understanding of turbine-passage stresses (pressure, shear stress, turbulence, strike) and information about the morphological, behavioral, and physiological characteristics of different fish taxa that make them susceptible to the stresses. Computational fluid dynamics and blade strike models of the turbine environment are re-examined in light of laboratory and field studies of fish passage effects. Comparisons of model-predicted stresses to measured injuries and mortalities will help identify fish survival thresholds and the aspects of turbines that are most in need of re-design. The coupled model and fish morphology evaluations will enable us to make predictions of turbine-passage survival among untested fish species, for both conventional and advanced turbines, and to guide the design of hydroelectric turbines to improve fish passage survival.

Cada, G. F.; Richmond, Marshall C.

2011-07-19

74

LTU Physlet: Ladder Leaning Against a Wall  

Science.gov (United States)

This Java Applet simulates the well-known "leaning ladder" physics problem. It consists of a ladder leaning against a wall and a person standing on the ladder (represented by a blue ball). The user can adjust mass of ladder, mass of person, distance person stands from base of ladder, coefficient of static friction underneath ladder, and the theta angle. Force vectors and values are shown for the lateral force and force of static friction on the base of the ladder. The ladder will fall if the lateral is greater than the frictional force. This is part of a larger collection of Physlet-based tutorials developed at Lawrence Technological University to support instruction of introductory physics.

Schneider, Scott

2011-09-02

75

46 CFR 108.160 - Vertical ladders.  

Science.gov (United States)

...2010-10-01 2010-10-01 false Vertical ladders. 108.160 Section 108.160 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... Construction and Arrangement Means of Escape § 108.160 Vertical ladders. (a) Each vertical...

2010-10-01

76

A Review and Modern Approach to LC Ladder Synthesis  

Directory of Open Access Journals (Sweden)

Full Text Available Ultra low power circuits require robust and reliable operation despite the unavoidable use of low currents and the weak inversion transistor operation region. For analogue domain filtering doubly terminated LC ladder based filter topologies are thus highly desirable as they have very low sensitivities to component values: non-exact component values have a minimal effect on the realised transfer function. However, not all transfer functions are suitable for implementation via a LC ladder prototype, and even when the transfer function is suitable the synthesis procedure is not trivial. The modern circuit designer can thus benefit from an updated treatment of this synthesis procedure. This paper presents a methodology for the design of doubly terminated LC ladder structures making use of the symbolic maths engines in programs such as MATLAB and MAPLE. The methodology is explained through the detailed synthesis of an example 7th order bandpass filter transfer function for use in electroencephalogram (EEG analysis.

Alexander J. Casson

2011-01-01

77

Laddering em pesquisa de marketing / Laddering in marketing research  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O artigo discute a técnica de pesquisa laddering em marketing, considerando a proposta de renovação de conhecimentos sobre metodologia na área. Para isso investiga diversos estudos, artigos e pesquisas que tratam do assunto em nível nacional e internacional. O conceito de cadeias meios-fins é aborda [...] do pela estrutura teórica que fundamenta a técnica, ligando atributos, conseqüências percebidas do consumo e valores pessoais relativos a um produto. O artigo segue com a explicação dos procedimentos de campo, como a entrevista e a análise dos dados. A laddering é um instrumento de pesquisa qualitativa bastante útil e poderoso, mas ainda pouco utilizado tanto por acadêmicos como por profissionais de mercado, no Brasil, provavelmente por desconhecimento e pouca divulgação. Cabe, portanto, uma maior disseminação de seu uso. Abstract in english The objective of this paper is to discuss laddering technique in marketing, considering the proposal of renewing knowledge on research methodology. It investigates national and international studies, articles, and researches that approach the subject. The means-end theory that grounds the technique, [...] linking attributes, consequences and values related to a product, is presented in the article. Common practices in the field research are presented as well, emphasizing data collection and analysis. Although very powerful, laddering is still underutilized for both academics and practitioners, probably for lacking of knowledge and dissemination. It is important to propagate the use of this technique in academic and market researches.

Tânia Modesto, Veludo-de-Oliveira; Ana Akemi, Ikeda.

78

Laddering em pesquisa de marketing Laddering in marketing research  

Directory of Open Access Journals (Sweden)

Full Text Available O artigo discute a técnica de pesquisa laddering em marketing, considerando a proposta de renovação de conhecimentos sobre metodologia na área. Para isso investiga diversos estudos, artigos e pesquisas que tratam do assunto em nível nacional e internacional. O conceito de cadeias meios-fins é abordado pela estrutura teórica que fundamenta a técnica, ligando atributos, conseqüências percebidas do consumo e valores pessoais relativos a um produto. O artigo segue com a explicação dos procedimentos de campo, como a entrevista e a análise dos dados. A laddering é um instrumento de pesquisa qualitativa bastante útil e poderoso, mas ainda pouco utilizado tanto por acadêmicos como por profissionais de mercado, no Brasil, provavelmente por desconhecimento e pouca divulgação. Cabe, portanto, uma maior disseminação de seu uso.The objective of this paper is to discuss laddering technique in marketing, considering the proposal of renewing knowledge on research methodology. It investigates national and international studies, articles, and researches that approach the subject. The means-end theory that grounds the technique, linking attributes, consequences and values related to a product, is presented in the article. Common practices in the field research are presented as well, emphasizing data collection and analysis. Although very powerful, laddering is still underutilized for both academics and practitioners, probably for lacking of knowledge and dissemination. It is important to propagate the use of this technique in academic and market researches.

Tânia Modesto Veludo-de-Oliveira

2008-03-01

79

Laddering em pesquisa de marketing / Laddering in marketing research  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: Portuguese Abstract in portuguese O artigo discute a técnica de pesquisa laddering em marketing, considerando a proposta de renovação de conhecimentos sobre metodologia na área. Para isso investiga diversos estudos, artigos e pesquisas que tratam do assunto em nível nacional e internacional. O conceito de cadeias meios-fins é aborda [...] do pela estrutura teórica que fundamenta a técnica, ligando atributos, conseqüências percebidas do consumo e valores pessoais relativos a um produto. O artigo segue com a explicação dos procedimentos de campo, como a entrevista e a análise dos dados. A laddering é um instrumento de pesquisa qualitativa bastante útil e poderoso, mas ainda pouco utilizado tanto por acadêmicos como por profissionais de mercado, no Brasil, provavelmente por desconhecimento e pouca divulgação. Cabe, portanto, uma maior disseminação de seu uso. Abstract in english The objective of this paper is to discuss laddering technique in marketing, considering the proposal of renewing knowledge on research methodology. It investigates national and international studies, articles, and researches that approach the subject. The means-end theory that grounds the technique, [...] linking attributes, consequences and values related to a product, is presented in the article. Common practices in the field research are presented as well, emphasizing data collection and analysis. Although very powerful, laddering is still underutilized for both academics and practitioners, probably for lacking of knowledge and dissemination. It is important to propagate the use of this technique in academic and market researches.

Tânia Modesto, Veludo-de-Oliveira; Ana Akemi, Ikeda.

2008-03-01

80

Getting Clever with the Sliding Ladder  

Science.gov (United States)

The familiar system involving a uniform ladder sliding against a vertical wall and a horizontal floor is considered again. The floor is taken to be smooth and the wall to be possibly rough--a situation where no matter how large the static friction coefficient between the ladder and the wall, the ladder cannot lean at rest and must slide down.…

De, Subhranil

2014-01-01

 
 
 
 
81

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...angle such that the horizontal distance from the top support to the...length of the ladder (the distance along the ladder between the...angle such that the horizontal distance is one-eighth the working...secured to prevent accidental displacement. (7) Ladders shall...

2010-07-01

82

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...provided with cages, wells, ladder safety devices...or (iii) A cage or well, and multiple ladder...the following: (i) Horizontal bands shall be fastened...distance between the bottom horizontal band and the next higher...of access. (21) Wells for fixed ladders...

2010-07-01

83

29 CFR 1917.118 - Fixed ladders.  

Science.gov (United States)

...Cage (basket guard) means a barrier enclosing... (2) Fixed ladder means a ladder, including...attached to a structure, building or piece of equipment...Ladder safety device means a support system limiting...20 feet (6.1 m) in height shall be provided...

2010-07-01

84

Shaft door with folding ladder  

International Nuclear Information System (INIS)

A shaft door is patented with a folding ladder which may easily be opened from the top and bottom of the shaft. It excludes the opening of the door by falling objects which improves work safety. This door is suitable for access shafts to biological protective cabins for repairs and maintenance inside nuclear reactors and for other purposes. (Ha)

85

The nonforward QCD ladder diagrams  

International Nuclear Information System (INIS)

We extend the standard analysis of the QCD planar ladder diagrams to the nonforward direction. Results are used for calculating exclusive and semiinclusive cross sections of diffractive photoproduction in the small-x region of ep-collisions. As an example we estimate the event rate for diffractive photoproduction of the neutral vector boson at Hera energies. (orig.)

86

Fish-Friendly Engineering  

Science.gov (United States)

Students further their understanding of the salmon life cycle and the human structures and actions that aid in the migration of fish around hydroelectric dams by playing an animated PowerPoint game involving a fish that must climb a fish ladder to get over a dam. They first brainstorm their own ideas, and then learn about existing ways engineers have made dams "friendlier" to migrating fish, before being quizzed as part of the game.

Integrated Teaching And Learning Program

87

Convergent validation study of the Contemplation Ladder for application via telephone in tobacco users Estudo da validação convergente da Escala de Contemplação Ladder aplicada por telefone em tabagistas  

Directory of Open Access Journals (Sweden)

Full Text Available OBJECTIVE: This work was designed to validate the Portuguese version of the Contemplation Ladder, whose purpose is to assess the motivational phase to quit smoking among tobacco users using a telephone service. METHOD: A cross-sectional study was conducted in a nationwide drug use information hotline. In order to assess the convergent validation, the correlation between the Contemplation Ladder and the URICA Scale was calculated, which was previously validated. RESULTS: The study included 271 tobacco users. Statistically significant correlations were found between the Contemplation Ladder scores and the scores of the URICA precontemplation (r=-0.16; pOBJETIVO: Este estudo teve como objetivo validar a versão em português da Escala de Contemplação Ladder, que visa verificar o estágio motivacional para parar de fumar em tabagistas, em um serviço de atendimento telefônico. MÉTODO: Um estudo transversal foi conduzido em um serviço de âmbito nacional de informação sobre uso de drogas por telefone. Para avaliação da validação convergente foi calculada a correlação entre a Escala de Contemplação Ladder e a Escala URICA, a qual já foi validada anteriormente. RESULTADOS: O estudo incluiu 271 tabagistas. Foram encontradas correlações estatisticamente significativas entre os escores da Escala de Contemplação Ladder e os escores das subescalas de pré-contemplação (r=-0,16; p<0,01, ação (r=0,15; p<0,01 e manutenção (r=0,18; p<0,01 da URICA. A correlação entre o escore composto da Escala URICA e a Escala de Contemplação Ladder também foi significativa (r=0,31; p<0,01. CONCLUSÃO: Os resultados do nosso estudo sugerem que a Escala de Contemplação Ladder pode ser uma alternativa para a Escala URICA (cuja aplicação dura no máximo 20 minutos, sem se impor uma carga maior de perguntas ao entrevistado. O estudo mostrou evidências de validade convergente da Escala de Contemplação Ladder, quando aplicada por telefone, em usuários de tabaco.

Mauro Barbosa Terra

2009-01-01

88

A Ladder of Thinking  

Science.gov (United States)

Introducing students to metacognition, or thinking about one's thinking, allows them to discover the value of reflection. Courses related to thinking theory are often included in the curriculum for high-achieving students, but these methods can also be used effectively to enhance the learning of average or below-average students. This article presents a lesson on top-down and bottom-up processing, two of the main ways in which people handle information. It is designed to help students understand why they should proceed slowly and deliberately when making observations in a science lab or when answering questions on a test.

Lovrich, Deborah

2004-04-01

89

46 CFR 116.438 - Stairtowers, stairways, ladders, and elevators.  

Science.gov (United States)

...Stairtowers, stairways, ladders, and elevators. 116.438 Section 116.438 Shipping...Stairtowers, stairways, ladders, and elevators. (a) A vessel carrying more than...requirements for stairways, ladders, and elevators in § 72.05-20 of this chapter....

2010-10-01

90

Mathematical model for definition of main design characteristics of average fishing trawlers  

Directory of Open Access Journals (Sweden)

Full Text Available The mathematical model is developed to define basic design characteris-tics of average fishing trawlers, allowing to increase their economic efficiency and to ensure the set parameters of vibration habitability. The model considers organization conditions of a fishing trade and results of statistical research for the ships of this type.

Lyong Hung Ngoc

2009-10-01

91

Walk-to-ladder Climb Transfer with Force Adjustment for a Multi-locomotion Robot  

Directory of Open Access Journals (Sweden)

Full Text Available This study presents a walk-to-ladder climb transfer for a Multi-locomotion Robot (MLR with force adjustment using a key joint method which has been developed originally for releasing the additional internal stress by changing a redundant position control joint to force control. Walk-to-ladder climb transfer is a multi-contact complicate robot motion with robot hands and feet cooperation. Three sub-motions were designed in this motion transfer: (1 Raise hands to catch the ladder’s rung, (2 Walk close to the ladder, (3 Climb on the ladder with legs. In order to compensate the position errors which always happened with position control, the key joint method has been studied in this study to improve the contact situations between the robot hand and the supporting rung. Experimental results show that this control method is effective for compensating the distance errors between hands and feet, thus the sliding of robot foot and the tumble problems has been prevented successfully. As a result, the MLR performs the walk-to-ladder climb transfer stably and smoothly.

Zhiguo Lu

2013-01-01

92

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...or wells. (i) Cages or wells (except on chimney ladders...construction. (ii) Cages or wells (except as provided in subparagraph...shall be clear of projections. Vertical bars shall be located at a...to center. (vi) Ladder wells shall have a clear width...

2010-07-01

93

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...except that each extra-heavy-duty type 1A metal or plastic ladder shall...except that each extra-heavy-duty type 1A metal or plastic ladders shall...loads caused by ice buildup, winds, rigging, and impact...

2010-07-01

94

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...buildup, winds, rigging, and impact loads resulting from the use...clear distance between the side rails of other fixed ladders shall...clear distance between side rails for all portable ladders shall...obtain a given length of side rail, the resulting side rail...

2010-07-01

95

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...of wood side rails and wood rungs or cleats, used...of 11/8 inches for wood ladders. (ii...section. All splices and connections shall have smooth transition...and rusting. (ii) Wood ladders, when used...incorporate lifebelts, friction brakes, and...

2010-07-01

96

Convergent validation study of the Contemplation Ladder for application via telephone in tobacco users / Estudo da validação convergente da Escala de Contemplação Ladder aplicada por telefone em tabagistas  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese OBJETIVO: Este estudo teve como objetivo validar a versão em português da Escala de Contemplação Ladder, que visa verificar o estágio motivacional para parar de fumar em tabagistas, em um serviço de atendimento telefônico. MÉTODO: Um estudo transversal foi conduzido em um serviço de âmbito nacional [...] de informação sobre uso de drogas por telefone. Para avaliação da validação convergente foi calculada a correlação entre a Escala de Contemplação Ladder e a Escala URICA, a qual já foi validada anteriormente. RESULTADOS: O estudo incluiu 271 tabagistas. Foram encontradas correlações estatisticamente significativas entre os escores da Escala de Contemplação Ladder e os escores das subescalas de pré-contemplação (r=-0,16; p Abstract in english OBJECTIVE: This work was designed to validate the Portuguese version of the Contemplation Ladder, whose purpose is to assess the motivational phase to quit smoking among tobacco users using a telephone service. METHOD: A cross-sectional study was conducted in a nationwide drug use information hotlin [...] e. In order to assess the convergent validation, the correlation between the Contemplation Ladder and the URICA Scale was calculated, which was previously validated. RESULTS: The study included 271 tobacco users. Statistically significant correlations were found between the Contemplation Ladder scores and the scores of the URICA precontemplation (r=-0.16; p

Mauro Barbosa, Terra; Dartiu Xavier da, Silveira; Taís de Campos, Moreira; Maristela, Ferigolo; Claudia, Mazoni; Fernanda Xavier, Arena; Helena Maria Tannhauser, Barros.

97

Development of Ladder Climbing Robot LCR-1  

International Nuclear Information System (INIS)

A new mobile robot has been developed, which is capable of ascending and descending vertical ladders such as those used in nuclear power plants and other facilities. The Ladder Climbing Robot releases personnel from dangerous and hard work at high places. The body of the robot has four grippers which grip each rung of the ladder as it ascends or descends. Each gripper is able to move up, down, forward or backward, and has two kinds of sensors to detect a rung: one photoelectric-switch and the other limit-switch. This robot can operate automatically or be remote controlled. Three of the grippers are continuously in contact with the ladder rungs to prevent falling. As a result of experiment, it has been confirmed that the prototype model LCR-1 for trial can ascend and descend automatically the actual vertical ladder with a micro-computer on the body. (author)

98

Discrete Breathers in Josephson Ladders  

CERN Document Server

We present a study of nonlinear localized excitations called discrete breathers in a superconducting array. These localized solutions were recently observed in Josephson-junction ladder arrays by two different experimental groups. We review the experiments made by Trias et al. We report the detection of different single-site and multi-site breather states and study the dynamics when changing the array bias current. By changing the temperature we can control the value of the damping (the Stewart-McCumber parameter) in the array, thus allowing an experimental study at different array parameters. We propose a simple DC circuit model to understand most of the features of the detected states. We have also compared this model and the experiments with simulations of the dynamics of the array. We show that the study of the resonances in the ladder and the use of harmonic balance techniques allow for understanding of most of the numerical results. We have computed existence diagrams of breather solutions in our arrays...

Trias, E; Brinkman, A C; Orlando, T P

2001-01-01

99

Discrete breathers in Josephson ladders  

Science.gov (United States)

We present a study of nonlinear localized excitations called discrete breathers in a superconducting array. These localized solutions were recently observed in Josephson-junction ladder arrays by two different experimental groups [Phys. Rev. Lett. 84 (2000) 741; Phys. Rev. Lett. 84 (2000) 745; Phys. Rev. E 62 (2000) 2858]. We review the experiments made by Tr?´as et al. [Phys. Rev. Lett. 84 (2000) 741]. We report the detection of different single-site and multi-site breather states and study the dynamics when changing the array bias current. By changing the temperature we can control the value of the damping (the Stewart-McCumber parameter) in the array, thus allowing an experimental study at different array parameters. We propose a simple DC circuit model to understand most of the features of the detected states. We have also compared this model and the experiments with simulations of the dynamics of the array. We show that the study of the resonances in the ladder and the use of harmonic balance techniques allow for understanding of most of the numerical results. We have computed existence diagrams of breather solutions in our arrays, found resonant localized solutions and described the localized states in terms of vortex and antivortex motion.

Trías, E.; Mazo, J. J.; Brinkman, A.; Orlando, T. P.

2001-08-01

100

Cutting and dismantling of the South West ladder of the Atucha I nuclear power plant  

International Nuclear Information System (INIS)

The metallic ladder built in stainless steel was used originally to check the welding of the reactor pressure vessel. It was located between the thermal insulation and reactor pressure vessel. Because of a failure in the mechanism, which let the ladder runs around the vessel, it had to be removed. A special tool remotely operated was designed to make different cuts in the bottom of the structure in a very high radioactive location

 
 
 
 
101

Sampling designs and methods for estimating fish-impingement losses at cooling-water intakes  

International Nuclear Information System (INIS)

Several systems for estimating fish impingement at power plant cooling-water intakes are compared to determine the most statistically efficient sampling designs and methods. Compared to a simple random sampling scheme the stratified systematic random sampling scheme, the systematic random sampling scheme, and the stratified random sampling scheme yield higher efficiencies and better estimators for the parameters in two models of fish impingement as a time-series process. Mathematical results and illustrative examples of the applications of the sampling schemes to simulated and real data are given. Some sampling designs applicable to fish-impingement studies are presented in appendixes

102

Dynamics of Josephson-junction ladders  

International Nuclear Information System (INIS)

We have numerically studied dynamical behaviors of Josephson-junction ladders consisting of Np plaquettes, where the 2(Np+1) superconducting islands are coupled by resistively shunted Josephson junctions with negligible capacitance. When a ladder is subjected to a current of the form Idc+Iacsin(?t) in the [10] direction the dc I-V curve, in the presence of a transverse external magnetic field, becomes a devil's staircase for Np=1, and exhibits hysteresis and a transition to chaos for Np?2. We have identified the ''symmetric state,'' where the phase variables of the junctions satisfy symmetry relations and motion of the system is constrained to the phase space of smaller dimension than the original one. The dynamic behavior of each junction in the ladder depends very sensitively on whether the number of the plaquettes in a ladder is odd or even. However, the averaged dc I-V curves of the whole ladders with Np?3 turn out similar to one another, enabling one to understand the dynamical behavior of a large ladder from that of a three-plaquette ladder

103

Dilogarithm ladders from Wilson loops  

CERN Document Server

We consider a light-like Wilson loop in N=4 SYM evaluated on a regular n-polygon contour. Sending the number of edges to infinity the polygon approximates a circle and the expectation value of the light-like WL is expected to tend to the localization result for the circular one. We show this explicitly at one loop, providing a prescription to deal with the divergences of the light-like WL and the large n limit. Taking this limit entails evaluating certain sums of dilogarithms which, for a regular polygon, evaluate to the same constant independently of n. We show that this occurs thanks to underpinning dilogarithm identities, related to the so-called polylogarithm ladders, which appear in rather different contexts of physics and mathematics and enable us to perform the large n limit analytically.

Bianchi, Marco S

2014-01-01

104

Phase separation in t-J ladders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The phase separation boundary of isotropic t-J ladders is analyzed using density matrix renormalization group techniques. The complete boundary to phase separation as a function of J/t and doping is determined for a chain and for ladders with two, three and four legs. Six-chain ladders have been analyzed at low hole doping. We use a direct approach in which the phase separation boundary is determined by measuring the hole density in the part of the system which contains both...

Rommer, Stefan; White, Steven R.; Scalapino, D. J.

1999-01-01

105

Teacher Evaluation and the Career Ladder.  

Science.gov (United States)

Surveys of Texas classroom teachers' attitudes were made in 1984, 1985, and 1986. Teachers' perceptions of competency testing, career ladders, teacher morale, teacher persistence, public support, and student achievement were requested. Results are presented. (MT)

Capps, Emerson; And Others

1987-01-01

106

A Laplace ladder of discrete Laplace equations  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The notion of a Laplace ladder for a discrete analogue of the Laplace equation is presented. The adjoint of the discrete Moutard equation and a discrete counterpart of the nonlinear form of Goursat equation are introduced.

Nieszporski, Maciej

2002-01-01

107

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...resist corrosion and rusting. (ii) Wood ladders, when used under conditions...or minimize the accumulation of water on wood parts. (iii) When different types...such as those that incorporate lifebelts, friction brakes, and sliding attachments...

2010-07-01

108

29 CFR 1917.118 - Fixed ladders.  

Science.gov (United States)

...Climbing devices such as step bolts or structural members of tanks and towers; (3) Ladders built into or vertically attached...consisting of individual rungs that are attached to walls, conical manhole sections or river cells shall: (1) Be capable...

2010-07-01

109

Clinical career ladders: Hamot Medical Center.  

Science.gov (United States)

The clinical career ladder program for pharmacists at Hamot Medical Center (HMC), a 500-bed not-for-profit community teaching hospital, is described. Between 1980 and 1989 a career ladder at HMC evolved from an idea to an established program with parallel administrative, business, and clinical tracks. The development of the career ladder mirrored the growth of clinical programs and the diversification of pharmaceutical services. A formal plan for a clinical ladder was developed when the first satellite pharmacy opened in 1984. An entry-level pharmacist at HMC starts with a six-month period during which he or she learns the drug distribution system and prepares for several certification tests. The employee is then promoted to staff pharmacist. Staff pharmacists are promoted to clinical pharmacist II (CP II) upon meeting requirements for competence in a broad range of clinical skills and knowledge. Candidates for the position of clinical pharmacist specialist (CP I) must have either a minimum of three years of experience as a CP II or a Pharm.D. degree and have established an area of clinical expertise. A CP I can progress to assistant and associate director positions as vacancies occur. The clinical ladder has enhanced job satisfaction and encouraged the development of clinical practitioners who provide improved care. Problems have included time constraints, competition for positions, and management of incentives. A parallel career ladder program with a clinical track has enhanced the growth of pharmacy practice at HMC and improved the quality of pharmaceutical care. PMID:2589340

Meyer, J D; Chrymko, M M; Kelly, W N

1989-11-01

110

Design and Development of Wireless Sensor Network System to Monitor Parameters Influencing Freshwater Fishes  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper we have designed, developed and proposed a prototype Wireless Sensor Network (WSN System to monitor the Fish Farm. Salinity of the fresh water is a prominent parameter and isresponsible for the difference in environment from marine conditions. Salt is an effective ingredient for fishes in fighting disease, parasites and chemical poisoning. The pH is equally a key parameter which influences the environment where fishes live. Generally, the fishes can live in pH ranges from 6.0 to 9.0, but their quality of life is best between pH 7.0 to 8.0. The change in the value of pH even by a small amount will be more stressful for fish. The temperature is other parameter which decides the value of pHand in turn affects the fishes. The developed prototype WSN system monitors these three parameters affecting the fresh water fishes. The open source technology-ARDUINO (open electronics prototype andopen source is used to develop the system.

Santoshkumar

2012-05-01

111

Hood River and Pelton Ladder Evaluation Studies : Annual Report 1994.  

Energy Technology Data Exchange (ETDEWEB)

In 1992, the Northwest Power Planning Council approved the Hood River and Pelton ladder master plans within the framework of the Columbia River Basin Fish and Wildlife Program. The master plans define an approach for implementing a hatchery supplementation program in the Hood River subbasin. The hatchery program as defined in the master plans is called the Hood River Hatchery Production Program (HRPP). The HRPP will be phased in over several years and will be jointly implemented by the Oregon Department of Fish and Wildlife (ODFW) and the Confederated Tribes of the Warm Springs (CTWS) Reservation. In December 1991, a monitoring and evaluation program was implemented in the Hood River subbasin to collect life history and production information on stocks of anadromous salmonids returning to the Hood River subbasin. The program was implemented to provide the baseline information needed to: (1) evaluate various management options for implementing the HRPP and (2) determine any post-project impacts the HRPP has on indigenous populations of resident fish. Information collected during the 1992-94 fiscal years will also be used to prepare an environmental impact statement (EIS) evaluating the program`s impact on the human environment. To begin construction on project facilities, it was proposed that the HRPP be implemented in two phases. Phase I would include work that would fall under a {open_quotes}categorical exclusion{close_quotes} from NEPA, and Phase II would include work requiring an EIS prior to implementation. This report summarizes the life history and escapement data collected in the Hood River subbasin and the status work of implemented under Phase I of the HR Life history and escapement data will be used to: (1) test the assumptions on which harvest and escapement goals for the Hood River and Pelton ladder master plans are based and (2) develop biologically based management recommendations for implementing the HRPP.

Olsen, Erik A.; French, Rod A.; Ritchey, Alan D.

1995-09-01

112

Fish schooling as a basis for wind farm design  

Science.gov (United States)

It is known that horizontal axis wind turbines (HAWT) suffer from reduced aerodynamic efficiency when in close proximity to neighboring turbines. In contrast, recent work has shown that closely spaced vertical axis wind turbines (VAWT) may benefit from enhanced performance, reducing the associated land use for VAWT wind farm installations. A potential flow model of VAWT interactions is developed to determine configurations that optimize the power output of the array. A geometric arrangement based on fish schooling has been shown to significantly increase the array performance as measured by an Array Power Coefficient, which compares the average performance of turbines in the array to an isolated turbine. The results suggest that significant gains may be obtained through careful arrangement of VAWTs, showing up to a two order of magnitude decrease in land use (equivalently, a two order of magnitude increase in power density) compared to HAWTs.

Whittlesey, Robert; Dabiri, John

2009-11-01

113

Doped spin ladders under magnetic field  

International Nuclear Information System (INIS)

This thesis deals with the physics of doped two-leg ladders which are a quasi one-dimensional and unconventional superconductor. We particularly focus on the properties under magnetic field. Models for strongly correlated electrons on ladders are studied using exact diagonalization and density-matrix renormalization group (DMRG). Results are also enlightened by using the bosonization technique. Taking into account a ring exchange it highlights the relation between the pairing of holes and the spin gap. Its influence on the dynamics of the magnetic fluctuations is also tackled. Afterwards, these excitations are probed by the magnetic field by coupling it to the spin degree of freedom of the electrons through Zeeman effect. We show the existence of doping-dependent magnetization plateaus and also the presence of an inhomogeneous superconducting phase (FFLO phase) associated with an exceeding of the Pauli limit. When a flux passes through the ladder, the magnetic field couples to the charge degree of freedom of the electrons via orbital effect. The diamagnetic response of the doped ladder probes the commensurate phases of the t-J model at low J/t. Algebraic transverse current fluctuations are also found once the field is turned on. Lastly, we report numerical evidences of a molecular superfluid phase in the 3/2-spin attractive Hubbard model: at a density low enough, bound states of four fermions, called quartets, acquire dominant superfluid fluctuations. The observed competition between the superfluid and density fluctuations is connected to the physics of doped ladders. (author)

114

Salmon jumping: behavior, kinematics and optimal conditions, with possible implications for fish passageway design  

Energy Technology Data Exchange (ETDEWEB)

Behavioral and kinematic properties and capacities of wild migratory salmonid fishes swimming upstream and jumping up waterfalls generally have played only minor roles in the design and construction of passageways intended to help these fishes get past dams and other human-made obstacles blocking their movements. This paper reports the results of an experimental study of relevant behavioral and kinematic properties of adult kokanee salmon (Oncorhynchus nerka) jumping up waterfalls as they migrate upstream. We used a portable, adjustable apparatus to study in the field fish responding to artificial waterfalls under a range of flow conditions. We observed fish under conditions of varying water flow rates, pool depths, fall heights and fall angles. We analyzed digital video recordings of their behaviors. Kokanee salmon spontaneously jump up waterfalls within a relatively narrow range of conditions, including low flow speeds, near vertical angles and pool depth to fall height ratios near 1.0. Preferred values for each parameter are, to some extent, dependent on other parameters. In contrast to previous misconceptions, jumping behavior is initiated by running S-start accelerations from beneath the boils formed in the plunge pools below waterfalls, as opposed to C-start standing jumps from the surface. S-starts are immediately followed by burst swimming to the point of takeoff at the surface. These results can contribute to an improved basis for developing designs of fish passageways that may ultimately make them more effective and efficient.

Lauritzen, D V; Jordan, L K; Gordon, M S [Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA 90095-1606 (United States); Hertel, F S, E-mail: dlauritz@ccsf.ed, E-mail: fritz.hertel@csun.ed, E-mail: msgordon@ucla.ed, E-mail: ljordan@ucla.ed [Department of Biology, California State University-Northridge, Northridge, CA 91330 (United States)

2010-09-15

115

Salmon jumping: behavior, kinematics and optimal conditions, with possible implications for fish passageway design  

International Nuclear Information System (INIS)

Behavioral and kinematic properties and capacities of wild migratory salmonid fishes swimming upstream and jumping up waterfalls generally have played only minor roles in the design and construction of passageways intended to help these fishes get past dams and other human-made obstacles blocking their movements. This paper reports the results of an experimental study of relevant behavioral and kinematic properties of adult kokanee salmon (Oncorhynchus nerka) jumping up waterfalls as they migrate upstream. We used a portable, adjustable apparatus to study in the field fish responding to artificial waterfalls under a range of flow conditions. We observed fish under conditions of varying water flow rates, pool depths, fall heights and fall angles. We analyzed digital video recordings of their behaviors. Kokanee salmon spontaneously jump up waterfalls within a relatively narrow range of conditions, including low flow speeds, near vertical angles and pool depth to fall height ratios near 1.0. Preferred values for each parameter are, to some extent, dependent on other parameters. In contrast to previous misconceptions, jumping behavior is initiated by running S-start accelerations from beneath the boils formed in the plunge pools below waterfalls, as opposed to C-start standing jumps from the surface. S-starts are immediately followed by burst swimming to the point of takeoff at the surface. These results can contribute to an improved basis for developing designs of fish passageways that may ultimately make them more effective and efficient.

116

5 CFR 335.104 - Eligibility for career ladder promotion.  

Science.gov (United States)

...false Eligibility for career ladder promotion. 335.104 Section 335.104 ...MANAGEMENT CIVIL SERVICE REGULATIONS PROMOTION AND INTERNAL PLACEMENT General Provisions...104 Eligibility for career ladder promotion. No employee shall receive a...

2010-01-01

117

Constructing a DNA ladder Range for Lambda Phage by multiplex PCR  

Directory of Open Access Journals (Sweden)

Full Text Available Background and Objectives: DNA ladder contains DNA fragments of different length but with known size, used to determine the size of unknown DNA molecules. Different DNA ladders are available for expected DNA length. Conserved sequences were selected for design of primers to generate DNA fragments of known specific size."nMaterials and Methods: In this study, we describe a method by which DNA ladder was prepared based on multiplex PCR technique. Different lengths of DNA fragments were amplified using the primers designed according to the 1216-2136 sequence extent of lambda phage DNA. Target DNA fragments were amplified using multiplex PCR and extracted."nResults: The results showed an amplified lambda phage DNA at particular target sites by using 1 forward and 6 different reverse primers (for 100, 200, 400, 600, 800, 1000bp for the successful amplification."nConclusion: This method would be more cost effective than commercial DNA molecular weight markers.

S Joseph

2010-12-01

118

Optimizing of the functionality of fish passes; Optimierung der Auffindbarkeit von Fischaufstiegsanlagen  

Energy Technology Data Exchange (ETDEWEB)

An important criterion of the correct operation of fish passes is their ease of localize for fishes and benthos willing to migrate upstream. If in practice an optimal solution can not be realized because of local restrictions, some aids can improve the functionality of fish ladders, such as a supplied tube, a fish attracting pump or a useful positioned fish deflector. (orig.)

Sobirey, Axel [WAGU GmbH Kassel (Germany)

2011-07-01

119

Comparative Phylogeography in Fijian Coral Reef Fishes: A Multi-Taxa Approach towards Marine Reserve Design  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Delineating barriers to connectivity is important in marine reserve design as they describe the strength and number of connections among a reserve's constituent parts, and ultimately help characterize the resilience of the system to perturbations at each node. Here we demonstrate the utility of multi-taxa phylogeography in the design of a system of marine protected areas within Fiji. Gathering mtDNA control region data from five species of coral reef fish in five genera and two families, we f...

Drew, Joshua A.; Barber, Paul H.

2012-01-01

120

Non-Abelian String-Net Ladders  

CERN Document Server

We study the string-net model with a string tension for non-Abelian particles in the ladder geometry. Focusing on the simplest non-Abelian theory with a total quantum dimension larger than two, we find evidence for a "russian doll" spectrum featuring size-independent energy levels. Contrary to Fibonacci and Ising ladders, the spectrum is found to be gapped at the self-dual points and low-energy excitations in the ground-state sector consist in two-quasiparticle bound states that are discussed in the weak-tension limit. We argue that such properties are prototypical of theories containing more than one non-Abelian particle.

Schulz, M D; Vidal, J

2014-01-01

 
 
 
 
121

Contribution of experimental fluid mechanics to the design of vertical slot fish passes  

Directory of Open Access Journals (Sweden)

Full Text Available This paper presents the main results of an experimental study of mean and turbulent characteristics of flow in a scale model of a vertical slot fish pass with varying width and slope (from 5% to 15%. Experimental hydraulic modelling was combined with the study of fish behaviour in the model. The discharge coefficient, which significantly affects the design of such facilities, varied from 0.67 to 0.89 and was strongly influenced by the slope. Two distinct flow patterns were observed, depending on the slope and the fish pass width. The point of transition between the two states was determined. Low velocity areas are likely resting zones for fish and particular attention was paid to evaluating these areas. Slope was found to affect both the volume of the low velocity zone, and the value of turbulent kinetic energy in these areas. The statistical characteristics of turbulent kinetic energy in the pools were linked primarily to the maximum velocity in the jet. An analysis of the behaviour of juvenile brown trout (Salmo trutta in the scale model clearly showed that the fish avoided the areas of high velocities in the jet, except at the slot itself where they took advantage of the jet’s non-stationary character. Low-velocity areas were not frequented uniformly by fish, which stayed most frequently in the zone located just downstream from the slot and behind the small side baffle. It is suggested that future studies might investigate lower pool-length to slot-width ratios, which might make it possible to increase the slope significantly and should also examine ways of improving hydraulic conditions for fish by carefully distributing obstacles in pools.

Wang R.W.

2010-02-01

122

DC/AC Student Guide: R2R Ladder Network  

Science.gov (United States)

R2R Ladder Networks provide a simple and inexpensive method of converting digital information to an analog signal. The R2R ladder circuit is a very common piece of almost all Digital-to-Analog converters.  By understanding how the R2R ladder system works, a better understanding of Digital-to-Analog converters can be had.

Casas, Jesus

2014-07-29

123

46 CFR 72.05-20 - Stairways, ladders, and elevators.  

Science.gov (United States)

...2010-10-01 false Stairways, ladders, and elevators. 72.05-20 Section 72.05-20...05-20 Stairways, ladders, and elevators. (a)(1) Except as further noted...area. (3) Stairways, ladders, and elevators within main machinery spaces or...

2010-10-01

124

29 CFR 1910.25 - Portable wood ladders.  

Science.gov (United States)

...2010-07-01 2010-07-01 false Portable wood ladders. 1910.25 Section 1910...Walking-Working Surfaces § 1910.25 Portable wood ladders. (a) Application of requirements...and use of the common types of portable wood ladders, in order to insure...

2010-07-01

125

Careers Under Construction: Models for Developing Career Ladders.  

Science.gov (United States)

This publication describes resources and processes that are a catalyst for discussion and action for local workforce investment partners--employers, training providers, and workers--to plan and implement regional career ladder programs. Section 1 discusses career ladders and uses. Section 2 describes how to build an industry career ladder or…

2003

126

Evaluation of Juvenile Fish Bypass and Adult Fish Facilities at Water Diversions in the Umatilla River; 1992 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

We report on our progress from October 1991 through September 1992 in evaluating juvenile fish bypass facilities at Three Mile Falls and Westland dams on the Umatilla River. We also report on our progress from October 1991 through June 1992 in evaluating adult fish passage in the lower Umatilla River and adult fish passage facilities at Three Mile Falls Dam. The study is a cooperative effort by the Oregon Department of Fish and Wildlife (ODFW) and the Confederated Tribes of the Umatilla Indian Reservation (CTUIR). These are the study objectives addressed by ODFW and CTUIR: (1) Report A (ODFW): To evaluate the juvenile fish bypass facility in the West Extension Irrigation District Canal at Three Mile Falls Dam and document juvenile salmonid passage through the juvenile fish bypass facility and east-bank adult fish ladder. To measure velocity and develop trap designs at Westland Dam. (2) Report B (CTUIR): To examine the passage of adult salmonids at Three Mile Falls Dam. The study is part of a program to rehabilitate anadromous fish stocks in the Umatilla River Basin, including restoration of coho salmon (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus tshawytscha), as well as enhancement of summer steelhead (Oncorhynchus mykiss).

Knapp, Suzanne M.

1993-03-01

127

Walla Walla River Fish Passage Operations Program, 2004-2005 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

In the late 1990s, the Confederated Tribes of the Umatilla Indian Reservation, Oregon Department of Fish and Wildlife, and Washington Department of Fish and Wildlife, along with many other agencies, began implementing fisheries restoration activities in the Walla Walla Basin. An integral part of these efforts is to alleviate the inadequate fish migration conditions in the basin. The migration concerns are being addressed by removing diversion structures, constructing fish passage facilities, implementing minimum instream flow requirements, and providing trap and haul efforts when needed. The objective of the Walla Walla River Fish Passage Operations Project is to increase the survival of migrating adult and juvenile salmonids in the Walla Walla River basin. The project is responsible for coordinating operation and maintenance of ladders, screen sites, bypasses, trap facilities, and transportation equipment. In addition, the project provides technical input on passage criteria and passage and trapping facility design and operation. Operation of the various passage facilities and passage criteria guidelines are outlined in an annual operations plan that the project develops. During the 2004-2005 project year, there were 590 adult summer steelhead, 31 summer steelhead kelts (Oncorhynchus mykiss), 70 adult bull trout (Salvelinus confluentus); 80 adult and 1 jack spring Chinook (O. tshawytscha) enumerated at the Nursery Bridge Dam fishway video counting window between December 13, 2004, and June 16, 2005. Summer steelhead and spring chinook were observed moving upstream while bull trout were observed moving both upstream and downstream of the facility. In addition, the old ladder trap was operated by ODFW in order to enumerate fish passage. Of the total, 143 adult summer steelhead and 15 summer steelhead kelts were enumerated at the west ladder at Nursery Bridge Dam during the video efforts between February 4 and May 23, 2005. Operation of the Little Walla Walla River juvenile trap for trap and haul purposes was not necessary this year.

Bronson, James P. (Confederated Tribes of the Umatilla Indian Reservation, Department of Natural Resources, Pendleton, OR); Duke, Bill B. (Oregon Department of Fish and Wildlife, Pendleton, OR)

2006-02-01

128

Calculated Investigation of Gravitational Sagging of ITS Outer Layer Model Ladder for ALICE and Optimization of Parameters of Ladder  

CERN Document Server

The report presents results of stiffness' calculations of the about 1.1 m length lightweight model ladder and some of its modifications for Inner Tracking System Abstract: for ALICE. As a result, dependences of the ladder's stiffness and mass Abstract: Abstract: characteristics on its geometrical parameters are investigated and an optimum structure of the ladder Abstract: (carbon fibre space frame) is determined.

Gloukhov, N P; CERN. Geneva

1996-01-01

129

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...extensive projections. (5) Electrolytic action. Adequate means...protect dissimilar metals from electrolytic action when such metals are...ladder to the nearest edge of equipment or structure shall be not...nearest edge of structure or equipment, a landing platform...

2010-07-01

130

Literature Ladders: Linking Books and Internet Resources.  

Science.gov (United States)

Describes Literature Learning Ladders, a project that uses books for children and young adults as the focal point for technology-rich thematic activities. Explains the use of Internet Web sites to find book information as well as sties that demonstrate how resources can be used as part of technology-based classroom activities. (LRW)

Lamb, Annette

2001-01-01

131

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...lifeline and the point of attachment to the body belt or harness...where they can be displaced by workplace activities or traffic, such...equipped with a single support attachment. (11) Ladders shall not...blocked (such as with a plywood attachment that spans several...

2010-07-01

132

Raman cross section of spin ladders  

CERN Document Server

We demonstrate that a two-triplet resonance strongly renormalizes the Raman spectrum of two-leg spin ladders and moreover suggest this to be the origin of the asymmetry of the magnetic Raman continuum observed in CaV2O5.

Jurecka, C; Friedrich, A; Brenig, W; Jurecka, Christoph; Gruetzun, Verena; Friedrich, Andreas; Brenig, Wolfram

2001-01-01

133

Hadron structure in the ladder model  

International Nuclear Information System (INIS)

The (flavor non-singlet) Green's function to find a far-off-shell quark in a hadron is obtained in the renormalization group improved ladder model for QCD in the space-like axial gauge. Particular attention is paid to the role of the singularity in the gluon propagator. 4 figures

134

Multiinstanton ladders in baryon number violating processes  

CERN Document Server

We estimate the contribution of a class of multiinstanton ladder graphs to baryon and lepton number violating processes in the standard model. We find that this contribution is negligible and does not alter the high energy behavior of the leading semiclassical approximation.

Lazarides, G

1995-01-01

135

Rope ladder routing: position-based multipath routing for wireless mesh networks  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, we present a novel multipath structure called rope-ladder which combines the advantages of path, node and link protection schemes. We also propose a position-based multipath routing protocol in order to efficiently construct rope-ladders in wireless networks. By design, the paths which are constructed by our protocol are closely together which allows to quickly switch back and forth between them in cases of node or link failures. Hence, the size of loss gaps (i.e. the number of...

Lessmann, Johannes; Schoeller, Marcus; Zdarsky, Frank A.

2010-01-01

136

Study of fish oil bleaching using the sodium bentonite through a factorial design  

Directory of Open Access Journals (Sweden)

Full Text Available This work was a experimental design in order to optimize the process of bleaching of fish oil, using the sodium bentonite as adsorbent, from the influence of variables such as weight of sodium bentonite, the temperature process, thermal activation of sodium bentonite and time of agitation. It was then possible to fit a mathematical model with the influence of each variable in the process of bleaching of the oil. The response variable was the absorbance at 444 nm.

Marcia Regina Simões

2011-06-01

137

Software documentation and user's manual for fish-impingement sampling design and estimation method computer programs  

International Nuclear Information System (INIS)

This report contains a description of three computer programs that implement the theory of sampling designs and the methods for estimating fish-impingement at the cooling-water intakes of nuclear power plants as described in companion report ANL/ES-60. Complete FORTRAN listings of these programs, named SAMPLE, ESTIMA, and SIZECO, are given and augmented with examples of how they are used

138

Design and implementation of a new autonomous sensor fish to support advanced hydropower development  

Science.gov (United States)

Acceleration in development of additional conventional hydropower requires tools and methods to perform laboratory and in-field validation of turbine performance and fish passage claims. The new-generation Sensor Fish has been developed with more capabilities to accommodate a wider range of users over a broader range of turbine designs and operating environments. It provides in situ measurements of three-dimensional (3D) linear accelerations, 3D rotational velocities, 3D orientation, pressure, and temperature at a sampling frequency of 2048 Hz. It also has an automatic floatation system and built-in radio-frequency transmitter for recovery. The relative errors of the pressure, acceleration, and rotational velocity were within ±2%, ±5%, and ±5%, respectively. The accuracy of orientation was within ±4° and accuracy of temperature was ±2 °C. The new-generation Sensor Fish is becoming a major technology and being deployed for evaluating the conditions for fish passage of turbines or other hydraulic structures in both the United States and several other countries.

Deng, Z. D.; Lu, J.; Myjak, M. J.; Martinez, J. J.; Tian, C.; Morris, S. J.; Carlson, T. J.; Zhou, D.; Hou, H.

2014-11-01

139

9 CFR 93.902 - Ports designated for the importation of live fish, fertilized eggs, and gametes.  

Science.gov (United States)

...fertilized eggs, and gametes. (a) The following ports are designated as ports of entry for live fish, fertilized eggs, and gametes...imported under this subpart: (1) Air and ocean ports . Los Angeles and San Francisco, CA;...

2010-01-01

140

Guest Editorial: Building Ladders to the Stars  

Science.gov (United States)

Young children love the stars and planets. They love the idea of leaving the Earth and traveling to the stars, of meeting aliens and exploring unknown worlds. Our goal in elementary school is to build the ladder to the stars and help students up the first few rungs by engaging them in explorations of the universe through some of the easily observable phenomena in the sky. After all, astronomy is the most beautiful, engaging, and life-enriching science out there!

George D. "Pinky" Nelson

2008-09-01

 
 
 
 
141

Entanglement spectra of quantum Heisenberg ladders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bipartite entanglement measures are fantastic tools to investigate quantum phases of correlated electrons. Here, I analyze the entanglement spectrum of **gapped** two-leg quantum Heisenberg ladders on a periodic ribbon partitioned into two identical periodic chains. Comparison of various entanglement entropies proposed in the literature is given. The entanglement spectrum is shown to closely reflect the low-energy gapless spectrum of each individual edge, for any sign of the...

Poilblanc, Didier

2010-01-01

142

Clinical ladder program implementation: a project guide.  

Science.gov (United States)

This article describes the development of a clinical ladder program (CLP) implementation linked to a promotion system for nurses. The CLP task force developed criteria for each level of performance and a performance evaluation tool reflecting the self-motivation of the applicant for professional development. One year after implementation, the number of nurses taking graduate courses increased, and 7 nurses were promoted to nurse manager positions. PMID:25340927

Ko, Yu Kyung; Yu, Soyoung

2014-11-01

143

Ladders for Wilson Loops Beyond Leading Order  

CERN Document Server

We set up a general scheme to resum ladder diagrams for the quark-anti-quark potential in N=4 super-Yang-Mills theory, and do explicit calculations at the next-to-leading order. The results perfectly agree with string theory in AdS(5)xS(5) when continued to strong coupling, in spite of a potential order-of-limits problem.

Bykov, D

2012-01-01

144

Raman Scattering cross section of Spin Ladders  

CERN Document Server

The Raman scattering spectra from magnetic excitations in anantiferromagnetic spin-1/2 two leg ladder is investigated for weak and stronginterladder coupling. In the first case, a cusp in the Raman intensityisobtained at a frequency twice the gap. In the second case, a peak at twice thegap replaces the cusp. We discuss the relevance of our calculation to recentexperiments on CaV2O5 and Sr14Cu24O41.

Orignac, E

2000-01-01

145

Magnetic properties of frustrated spin ladder  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The magnetic properties of the antiferromagnetic spin ladder with the next-nearest neighbor interaction, particularly under external field, are investigated by the exact diagonalization of the finite clusters and size scaling techniques. It is found that there exist two phases, the rung-dimer and rung-triplet phases, not only in the nonmagnetic ground state but also magnetized one, where the phase boundary has a small magnetization dependence. Only in the former phase, the m...

Sakai, Toru; Okazaki, Nobuhisa

2000-01-01

146

Raman Scattering cross section of Spin Ladders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Raman scattering spectra from magnetic excitations in an antiferromagnetic spin-1/2 two leg ladder is investigated for weak and strong interladder coupling. In the first case, a cusp in the Raman intensityis obtained at a frequency twice the gap. In the second case, a peak at twice the gap replaces the cusp. We discuss the relevance of our calculation to recent experiments on CaV2O5 and Sr14Cu24O41.

Orignac, E.; Citro, R.

2000-01-01

147

Dynamic Spin Response for Heisenberg Ladders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We employ the recently proposed plaquette basis to investigate static and dynamic properties of isotropic 2-leg Heisenberg spin ladders. Simple non-interacting multi-plaquette states provide a remarkably accurate picture of the energy/site and dynamic spin response of these systems. Insights afforded by this simple picture suggest a very efficient truncation scheme for more precise calculations. When the small truncation errors are accounted for using recently developed Cont...

Piekarewicz, J.; Shepard, J. R.

1997-01-01

148

Excitation spectrum of Heisenberg spin ladders  

International Nuclear Information System (INIS)

Heisenberg antiferromagnetic spin ''ladders'' (two coupled spin chains) are low-dimensional magnetic systems which for S=1/2 interpolate between half-integer-spin chains, when the chains are decoupled, and effective integer-spin one-dimensional chains in the strong-coupling limit. The spin-1/2 ladder may be realized in nature by vanadyl pyrophosphate, (VO)2P2O7. In this paper we apply strong-coupling perturbation theory, spin-wave theory, Lanczos techniques, and a Monte Carlo method to determine the ground-state energy and the low-lying excitation spectrum of the ladder. We find evidence of a nonzero spin gap for all interchain couplings Jperpendicular>0. A band of spin-triplet excitations above the gap is also analyzed. These excitations are unusual for an antiferromagnet, since their long-wavelength dispersion relation behaves as (k-k0)2 (in the strong-coupling limit Jperpendicular much-gt J, where J is the in-chain antiferromagnetic coupling). Their band is folded, with a minimum energy at k0=?, and a maximum between k1=?/2 (for Jperpendicular=0) and 0 (for Jperpendicular=?). We also give numerical results for the dynamical structure factor S(q,?), which can be determined in neutron scattering experiments. Finally, possible experimental techniques for studying the excitation spectrum are discussed

149

Box ladders in non-integer dimension  

CERN Document Server

We construct a class of triangle-ladder diagrams which can be calculated by making a use of Belokurov-Usyukina loop reduction technique in d = 4 -2e dimensions. The main idea of the approach consists in generalization of this loop reduction technique existing in d = 4 dimensions. The recursive formula relating L-loop result for any triangle ladder of that class and (L-1)-loop result for another triangle ladder of the same class is derived. Since the method proposed in the present paper combines analytic and dimensional regularizations, at the end of the calculation we have to remove the analytic regularization by taking the limit in which the parameters of the analytic regularization are vanishing. In this limit on the left hand side of the recursive relations we obtain in the position space the diagram in which the indices of the rungs are 1 and all the other indices are 1-e. Fourier transforms of this type of diagrams are the momentum space diagrams which have indices of the rungs equal to 1-e and all the o...

Gonzalez, Ivan

2012-01-01

150

Effects of uniaxial pressure in cuprate ladder compound  

International Nuclear Information System (INIS)

Strain and resistivity measurements were performed under uniaxial pressure on single crystals of Sr2.5Ca11.5Cu24O41 (superconductive under isotropic pressure over 2GPa) to clarify the role of pressure in the ladder superconductivity. Compressibility along the uniaxial pressure is the largest in the layer-stacking direction. By increasing the compression of the layer-spacing, the ladder planes are expanded and the resistive component both along and across the ladders are found to decrease monotonically. This indicates that a charge transfer from the CuO2-chain planes to the Cu2O3-ladder planes is promoted by the layer compression

151

D0 Silicon Upgrade: Thermal Analysis of the D0 3 CHIP Single Sided Ladder  

International Nuclear Information System (INIS)

The design of the D0 single sided 3 chip ladder is shown in figures 1-3. The SVX II chips are mounted directly opposite the cooling channel so that they are most efficiently cooled. Outboard of the cooling channel on the ladder top side is mounted a flex hybrid of copper/kapton. which is adhered to a beryllium substrate using a two part epoxy. The beryllium substrate. aside from providing a solid mounting structure for the flex circuit. provides a thermal conduction path between the components on the hybrid which dissipate heat and the cooling channel. The thickness of the top and bottom beryllium substrates is selected based on the (expected) channel temperature. the power dissipation of the SVX II chips, the power dissipation of the hybrid passive components, and the maximum acceptable silicon temperature within the ladder. The thermal conductivity of the various materials within the ladder must be known to a fair degree of confidence in order to accurately simulate the ladder steady state cooling performance. The thermal conductivity of a number of ladder epoxy candidates was measured using a device at Lab D at Fermilab. Preliminary measurements at Lab D, using a similar setup. have been performed in order to measure the thermal conductivity of beryllium. silicon, aluminum, and other ladder materials. In order to simulate the cooling performance with confidence. prototype ladders were constructed using aluminum substrates (in place of beryllium), blank silicon, and nonfunctional prototype flex hybrid circuits. SVX II heat loads were simulated using 350 ohm strain gages which were adhered to the flex hybrid using a thin layer of epoxy. Temperatures were measured on the prototype ladders using a hand-held IR temperature probe, which has a laser focusing beam enabling simple optical focal length determination. The IR probe allows a correction to account for the surface emissivity of the material being measured. Preliminary measurements at Lab D indicate that the alloy used to construct the ladder models has a conductivity of 237 W/m-K. The assumed conductivity of the blank silicon is 149 W/m-K. Ladder prototypes with aluminum substrates were constructed using the prototype 3 chip assembly fixture at Lab D. A two dimensional cooling simulation program was written using a simultaneous equation solver. The simulation is written by dividing the 2D model into small dx and dy elements and performing an energy balance on each element based on the thermal resistance between the individual elements and their neighbors. It is otherwise known as the finite difference method. The steady state solution is obtained by solving the array of energy balance equations as a DC circuit Convective boundaries can be added on exposed elements using appropriate equations. Following is a schematic which shows the energy balance terms in each element.

152

Designing a mathematical model of management techniques (TQM, BPR in Zahedan , weave fishing net industries  

Directory of Open Access Journals (Sweden)

Full Text Available Currently reengineering and Total Quality Management (TQM techniques known improvement in organizations. in this research initially a Mathematical model was designed to find out the main factors in relative reengineering and TQM. Based on finding factors of Model, a 40 element questionary formed and the questionnaire distributed among the staff of fishing net factory in a random order, finding by using of SPSS, the data analyzed and concluding Remark shows the installation and acceptance of TQM by using reengineering is possible to the factory.

Dr.Baqer Kord, Dr. Habibollah Salarzehi, Hamed Aramesh, Somayeh Mousavi

2010-10-01

153

Ladder-type SAW filters using thinned density of randomly distributed "hot" electrodes.  

Science.gov (United States)

A new method for the design of relatively narrowband ladder-type SAW filters is proposed. It consists of the thinning procedure and consecutive randomization of positions of the remaining transductive periods inside the IDT to suppress undesirable additional passbands. A 0.9% fractional bandwidth filter on LiTaO(3) 42°-cut was designed and manufactured using the proposed approach. PMID:21041145

Kim, Che-Uk; Balashov, Sergey M; Plessky, Victor P; Nam, Chang-Woo; Lee, Kyu-Chul

2010-11-01

154

Magnetization Plateau in the Frustrated Spin Ladder  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The magnetization process of the S=1/2 antiferromagnetic spin ladder at T=0 is studied by the exact diagonalization of finite clusters and size scaling analyses. It is found that a magnetization plateau appears at half the saturation value (m=1/2) in the presence of a sufficiently large next-nearest-neighbor exchange interaction to yield the frustration, when the rung coupling is larger than the leg one. The phase diagram at m=1/2 is given by the analysis based on the confor...

Okazaki, Nobuhisa; Miyoshi, Junji; Sakai, Toru

1999-01-01

155

46 CFR 92.10-15 - Vertical ladders not accepted.  

Science.gov (United States)

(a) Vertical ladders and deck scuttles shall not in general be considered satisfactory as one of the required means of escape. However, where it is demonstrated that the installation of a stairway would be impracticable, a vertical ladder may be used as the second means of...

2010-10-01

156

Discussing Laddering Application by the Means-End Chain Theory  

Science.gov (United States)

This article aims at analyzing laddering as a technique of qualitative research, emphasizing the procedures for data collection, analysis and interpretation, and its main limitations as well. "Laddering refers to an in-depth, one-on-one interviewing technique used to develop an understanding of how consumers translate the attributes of products…

Veludo-de-Oliveira, Tania Modesto; Ikeda, Ana Akemi; Campomar, Marcos Cortez

2006-01-01

157

Function control of fish bypass facilities. Necessity and techniques; Funktionskontrolle von Fischaufstiegsanlagen. Notwendigkeit und Methodik  

Energy Technology Data Exchange (ETDEWEB)

The necessity and practical implementation of fish ladders have been discussed in various contributions during the past few years. This publication presents the various viewpoints and attempts a critical evaluation on the basis of ecological and economic aspects. (orig.)

Ebel, G. [Buero fuer Gewaesseroekologie und Fischereibiologie Dr. Ebel (BGF), Halle (Saale) (Germany); Fredrich, F. [Leibniz-Institut fuer Gewaesseroekologie und Binnenfischerei im Forschungsverbund Berlin e.V. (Germany); Gluch, A. [Landesbetrieb fuer Hochwasserschutz und Wasserwirtschaft Sachsen-Anhalt (LHW), Halle (Saale) (Germany); Lecour, C. [Niedersaechsisches Landesamt fuer Verbraucherschutz und Lebensmittelsicherheit (LaVes), Hannover (Germany). Inst. fuer Fischkunde Cuxhaven, Abt. Binnenfischerei; Wagner, F. [Institut fuer Gewaesseroekologie und Fischereibiologie (IGF), Jena (Germany)

2007-07-01

158

Frequency Synchronization in Disordered, Underdamped Josephson Ladders  

Science.gov (United States)

We simulated via the RCSJ model ladder arrays of underdamped Josephson junctions with critical current disorders of up to 5% and over a wide range of McCumber parameters (1??_c? 100). When the junctions are current biased above their critical currents, coupling between the neighboring junctions that make up the rungs of the ladder can result in voltage oscillations across different junctions that have the same frequency. Such frequency synchronization is found to occur once the junction coupling strength, ?, is increased to a critical value. We report on the synchronization behavior of the RCSJ model as a function of: array size, amount of critical current disorder, McCumber parameter, as well as for both periodic and open boundary conditions. We also used a multiple time scale perturbation method to derive an averaged version of the RCSJ equations. The result is an extension of the standard Kuramoto model for the case of nearest-neighbor couplings which includes the effects of oscillator inertia. One consequence of the underdamped (inertial) nature of the arrays is hysteretic behavior in the synchronization as ? is increase and decreased. This work was supported by the OWU Summer Science Research Program.

Trees, B. R.; Saranathan, V.

2004-03-01

159

Designing and validating the methodology for the Internet assessment of fish consumption at a university setting  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Assessing fish consumption is complex and involves several factors; however, the use of questionnaires in surveys and the use of the Internet as tool to collect data have been considered promising approaches. Therefore, the objective of this research was to design a data collection technique using a [...] questionnaire to assess fish consumption by making it available on a specific home page on the Internet. A bibliographical survey or review was carried out to identify the features of the instrument, and therefore pre-tests were conducted with previous instruments, followed by the Focus Group technique. Specialists then performed an analysis and conducted an online pre-test. Multivariate data analysis was applied using the SmartPLS software. The results indicate that 1.966 participants belonging to the University of São Paulo (USP) community participated in the test, and after the exclusion of some variables, a statistically significant results were obtained. The final constructs comprised consumption, quality, and general characteristics. The instrument consisted of behavioral statements in a 5-point Likert scale and multiple-choice questions. The Cronbach's alpha reliability coefficient was 0.66 for general characteristics, 0.98 for quality, and 0.91 for consumption, which indicate good reliability of the instrument. In conclusion, the results proved that the Internet assessment is efficient. The instrument of analysis allowed us to better understand the process of buying and consuming fish in the country, and it can be used as base for further research.

Erika da Silva, Maciel; Julia Santos, Vasconcelos; Luciana Kimie Savay da, Silva; Jaqueline Girnos, Sonati; Juliana, Galvão; Dirceu da, Silva; Marília, Oetterer.

2014-06-01

160

Designing and validating the methodology for the Internet assessment of fish consumption at a university setting  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english Assessing fish consumption is complex and involves several factors; however, the use of questionnaires in surveys and the use of the Internet as tool to collect data have been considered promising approaches. Therefore, the objective of this research was to design a data collection technique using a [...] questionnaire to assess fish consumption by making it available on a specific home page on the Internet. A bibliographical survey or review was carried out to identify the features of the instrument, and therefore pre-tests were conducted with previous instruments, followed by the Focus Group technique. Specialists then performed an analysis and conducted an online pre-test. Multivariate data analysis was applied using the SmartPLS software. The results indicate that 1.966 participants belonging to the University of São Paulo (USP) community participated in the test, and after the exclusion of some variables, a statistically significant results were obtained. The final constructs comprised consumption, quality, and general characteristics. The instrument consisted of behavioral statements in a 5-point Likert scale and multiple-choice questions. The Cronbach's alpha reliability coefficient was 0.66 for general characteristics, 0.98 for quality, and 0.91 for consumption, which indicate good reliability of the instrument. In conclusion, the results proved that the Internet assessment is efficient. The instrument of analysis allowed us to better understand the process of buying and consuming fish in the country, and it can be used as base for further research.

Erika da Silva, Maciel; Julia Santos, Vasconcelos; Luciana Kimie Savay da, Silva; Jaqueline Girnos, Sonati; Juliana, Galvão; Dirceu da, Silva; Marília, Oetterer.

 
 
 
 
161

Molecular Sieves: Energy-Efficient Hydrogen Separation by AB-Type Ladder-Polymer Molecular Sieves (Adv. Mater. 39/2014).  

Science.gov (United States)

I. Pinnau and co-workers on page 6696 describe intrinsically ultramicroporous ladder polymers developed for energy-efficient membrane-based hydrogen separation. The versatility of an AB synthetic approach in the integration of 3D triptycene moieties into highly rigid, fully fused-ring ladder polymers yields strongly size-sieving membrane materials with exceptionally high hydrogen permeability. These novel polymeric sieves are illustrated in this cover page by Ying Zhao of Warmspace Design Inc. PMID:25319152

Ghanem, Bader S; Swaidan, Raja; Ma, Xiaohua; Litwiller, Eric; Pinnau, Ingo

2014-10-01

162

Synthesis of DNA Ladder by Polymerase Chain Reaction and Optimization of Yield Using Response Surface Methodology  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A factorial design approach was applied to optimize the PCR yield of 2 kb fragment involved in preparing DNA ladder. On applying response surface methodology, the effect of six independent variables was studied. From this study we concluded that three fold increase was obatainable upon optimization under the following conditions: primer concentration, 10 pmole; number of cycles, 24; Taq concentration, 2.75 U; Mg+2 concentration, 1.97 mM; annealing temperature, 57°C and exte...

Abdel-fattah, Yasser R.; Gaballa, Ahmed A.

2006-01-01

163

Magnetic responses of randomly depleted spin ladders  

Science.gov (United States)

The magnetic responses of a spin-1/2 ladder doped with nonmagnetic impurities are studied combining both analytical and numerical methods. The regime where frustration induces incommensurability is taken into account. Several improvements are made on the results of the seminal work by Sigrist and Furusaki [M. Sigrist and A. Furusaki, J. Phys. Soc. Jpn.JUPSAU0031-901510.1143/JPSJ.65.2385 65, 2385 (1996)] and deviations from the Brillouin magnetization curve due to interactions are also analyzed. We first discuss the magnetic profile around a single impurity and the effective interactions between impurities within the bond-operator mean-field theory. The results are compared to density-matrix renormalization group calculations. In particular, these quantities are shown to be sensitive to the transition to the incommensurate regime. We then focus on the behavior of the zero-field susceptibility through an effective Curie constant. At zero temperature, we give doping-dependent corrections to the results of Sigrist and Furusaki on general bipartite lattices and compute exactly the distribution of ladder clusters due to chain breaking effects. Solving the effective model with exact diagonalization and quantum Monte Carlo simulations gives the temperature dependence of the Curie constant. Its high-temperature limit is understood within a random dimer model, while the low-temperature tail is compatible with a real-space renormalization group scenario. Interestingly, solving the full microscopic model does not show a plateau corresponding to the saturation of the impurities in isotropic ladders. The second magnetic response that is analyzed is the magnetic curve. Below fields of the order of the spin gap, the magnetization process is controlled by the physics of interacting impurity spins. The random dimer model is shown to capture the bulk of the curve, accounting for the deviation from a Brillouin behavior due to interactions. The effective model calculations agree rather well with density-matrix renormalization group calculations at zero temperature and with quantum Monte Carlo simulations at finite temperature. In all, the effect of incommensurability does not display a strong qualitative effect on both the magnetic susceptibility and the magnetic curve. Consequences for experiments on the BiCu2PO6 compound and other spin-gapped materials are briefly mentioned.

Lavarélo, Arthur; Roux, Guillaume; Laflorencie, Nicolas

2013-10-01

164

Macrocomposite mechanical design, modeling, and behavior of physical models of bioinspired fish armor  

Science.gov (United States)

The macrocomposite design of flexible biological exoskeletons, consisting of overlapping mineralized armor units embedded in a compliant tissue, is a key determinant of their mechanical function (e.g penetration resistance and biomechanical flexibility). Here, we investigate the role of macrocomposite structure, composition, geometric orientation, and spatial distribution in a flexible model natural armor system present in the majority of teleost fish species. Physical multi-material composite models are fabricated using a combination of 3-D printing and molding methods. Mechanical experiments using digital image correlation enable measurement of both the macroscopic response and underlying deformation mechanisms during various loading scenarios. Finite element-based mechanical models yield detailed insights into the roles and the tradeoffs of the composite structure providing constraint, shear, and bending mechanisms to impart protection and flexibility.

Browning, Ashley; Ortiz, Christine; Boyce, Mary C.

2012-02-01

165

Inhomogeneously doped two-leg ladder systems  

CERN Document Server

A chemical potential difference between the legs of a two-leg ladder is found to be harmful for Cooper pairing. The instability of superconductivity in such systems is analyzed by compairing results of various analytical and numerical methods. Within a strong coupling approach for the t-J model, supplemented by exact numerical diagonalization, hole binding is found unstable beyond a finite, critical chemical potential difference. The doping dependent phase diagram of the t-J model, obtained from spinon-holon mean field theory, indicates a stepwise reduction of superconductivity upon increasing the chemical potential difference. Based on a renormalization group approach and Abelian bosonization, similar conclusions are reached for the weakly interacting Hubbard model.

Wessel, S; Laeuchli, A; Ledermann, U; Sigrist, M; Wessel, Stefan; Indergand, Martin; Laeuchli, Andreas; Ledermann, Urs; Sigrist, Manfred

2002-01-01

166

Field-induced superconductivity in a spin-ladder cuprate.  

Science.gov (United States)

We report on the modulation of the transport properties of thin films, grown by molecular beam epitaxy, of the spin-ladder compound [CaCu2O3]4, using the field effect in a gated structure. At high hole-doping levels, superconductivity is induced in the nominally insulating ladder material without the use of high-pressure or chemical substitution. The observation of superconductivity is in agreement with the theoretical prediction that holes doped into spin ladders could pair and possibly superconduct. PMID:11577230

Schön, J H; Dorget, M; Beuran, F C; Xu, X Z; Arushanov, E; Laguës, M; Deville Cavellin, C

2001-09-28

167

A tunable split-ladder photonic crystal cavity by nanoelectromechanical actuator  

Science.gov (United States)

In this paper, we demonstrate a novel split-ladder photonic crystal cavity, which can be tuned across a very large wavelength range by an on-chip integrated nano-electromechanical actuator. The nano-electromechanical actuator is used to control the cavity's central gap. When the cavity gap is widened, the resonance wavelength is blue-shifted correspondingly. The dimensions of the proposed split-ladder cavity are designed by 3D Finite-difference time-domain (FDTD) calculations. We fabricated and tested the devices. Experimental results show that the optomechanical coupling coefficient of the second order resonance mode is about 80 GHz/nm. In addition, there is a relatively linear relationship between the resonance shift and the gap change. The maximum measured resonance wavelength shift is about 17 nm, corresponding to a cavity central gap increase of 26 nm.

Tian, Feng; Zhou, Guangya; Chau, Fook Siong; Deng, Jie; Akkipeddi, Ramam; Tang, Xiaosong; Teo, Siew Lang; Loke, Yee Cheong

2013-03-01

168

Evaluation of swimming capability and potential velocity barrier problems for fish. Part A: Swimming performance of selected warm and cold water fish species relative to fish passage and fishway design  

International Nuclear Information System (INIS)

The objective of this study was to provide information about the swimming capability of several widely distributed, economically or recreationally important fish species, for use in mitigating potential velocity barrier problems associated with hydroelectric power facilities. Swimming capability of anadromous and landlocked Atlantic salmon, brook trout, brown trout, lake sturgeon, and walleye, collected from various locations throughout Canada, were investigated to develop criteria for sustained, prolonged, burst swimming performance characteristics of the study species, fish physiology, life history and migration distance on swimming performance. Swimming performance characteristics in the wild, especially the use of physiological telemetry, as well as development of new methodology for the measurement of burst speed was also central to the study. Models were derived to describe swimming capabilities for each study species/life stage in relation to fish length, water velocity, water temperature, and other significant environmental factors. The data will form the basis of guideline development and decision making to improve design and evaluation of fish passage facilities. A series of annotated bibliographies resulting from the study are described in Appendix B. 74 refs., 8 tabs., figs., 2 appendices

169

Design and Analysis of an Underwater White LED Fish-Attracting Lamp and Its Light Propagation  

Directory of Open Access Journals (Sweden)

Full Text Available Light emitting diodes (LED are a new source for replacing traditional light sources including under water illumination. As traditional underwater light sources operate under a radiative transfer model, the luminous intensity is dispersed evenly at each emission angle, with the scattering factors included in the attenuation coefficient. By contrast, LED light sources are characterized by being highly directional, causing underwater luminous energy to vary with different emission angles. Thus, the traditional theory of underwater optical transfer becomes inapplicable when an underwater LED lighting module is designed. Therefore, to construct an underwater transfer model for LED light sources, this study employed the average cosine of the underwater light field, the method for light scattering probability, the LED luminous intensity distribution curve (LIDC and axial luminous intensity. Afterwards, an underwater LED fish?attracting lamp was designed. Experimental results showed that, compared with the simulation values, the luminous intensity of the underwater LED lighting module at all emission angles had a percentage error of less than 10%.

Sheng Chih Shen

2013-03-01

170

Entanglement in resonating valence bond states: ladder versus isotropic lattices  

Energy Technology Data Exchange (ETDEWEB)

We study the behavior of bipartite, as well as genuine multipartite, entanglement of a resonating valence bond state on a ladder. Although there is negligible bipartite entanglement (BE) present in the rails, as is the case for isotropic lattices in two and higher dimensions, we show that the system possesses significant amounts of BE in the steps of the ladder. However, we find that the genuine multipartite entanglement in the system is substantially low. Therefore, both the properties of bipartite as well as multipartite entanglement in the ladder are contrary to the behavior of entanglement in isotropic lattices, indicating that the geometry of the lattice can play a significant role in quantum information processing tasks. Our results also indicate that numerical and analytical investigations obtained on ladders cannot infer the same on two-dimensional lattices. (paper)

Dhar, Himadri Shekhar; Sen, Aditi, E-mail: aditi@hri.res.in [School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110067 (India)

2011-11-18

171

Entanglement in resonating valence bond states: ladder versus isotropic lattices  

International Nuclear Information System (INIS)

We study the behavior of bipartite, as well as genuine multipartite, entanglement of a resonating valence bond state on a ladder. Although there is negligible bipartite entanglement (BE) present in the rails, as is the case for isotropic lattices in two and higher dimensions, we show that the system possesses significant amounts of BE in the steps of the ladder. However, we find that the genuine multipartite entanglement in the system is substantially low. Therefore, both the properties of bipartite as well as multipartite entanglement in the ladder are contrary to the behavior of entanglement in isotropic lattices, indicating that the geometry of the lattice can play a significant role in quantum information processing tasks. Our results also indicate that numerical and analytical investigations obtained on ladders cannot infer the same on two-dimensional lattices. (paper)

172

Quantum phase competition in antiferromagnetic spin-1 ladders  

International Nuclear Information System (INIS)

Motivated by recent chemical explorations into organic-radical-based higher-spin ladder systems, we study the ground-state properties of a wide class of antiferromagnetic spin-1 ladders. Numerical analysis featuring the level-spectroscopy technique reveals the rich phase diagram, correcting a preceding nonlinear-sigma-model prediction. A variational analysis well interprets the phase competition with particular emphasis on the re-entrant phase boundary on the way from single to coupled chains. (author)

173

Bond Disorder in Even-Leg Heisenberg Ladders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Random bond disorder in antiferromagnetic spin-1/2 Heisenberg ladders is investigated using the Stochastic Series Expansion Quantum Monte Carlo method. We find that the effects of individual bond impurities vary strongly, depending on their position on legs and rungs. We initially focus on how the distribution of local bond energies depends on the impurity concentration. Then we study how the phase diagram of even-leg ladders is affected by random bond doping. We observe Bos...

Trinh, Kien; Haas, Stephan

2012-01-01

174

Spreading Design of Radioactivity in Sea Water, Algae and Fish Samples inthe Coastal of Muria Peninsula Area  

International Nuclear Information System (INIS)

Spreading design of radioactivity in sea water, brown algae (phaeopyceae)and kerapu fish (epeniphelus) samples in the coastal of Muria peninsula areahas been studied. This research was carried out with designed beside to knowspreading each radioactivity but also spreading design in relation to thecontent of Pu-239 and Cs-137. Samples taken, preparation and analysis basedon the procedures of environmental radioactivity analysis. The instrumentused for the analysis radioactivity were alpha counter with detector ZnS, lowlevel beta counter modified P3TM-BATAN with detector GM and spectrometergamma with detector Ge(Li). Alpha radioactivity obtained of sea water, algaeand fish were the fluctuation form of the natural background. Radionuclide ofPu-239 in samples not detect, because its concentration/radioactivity stillbelow the maximum concentration detection value of Pu-239 for algae and fishwas that 1.10 Bq/g, whereas for sea water was that 0.07 Bq/mL. Result for theradioactivity which give the highest alpha radioactivity obtained on thekerapu fish was that 1.56 x 10-3 Bq/g, beta radioactivity on sea water wasthat 1.75 x 102 mBq/L, gamma radioactivity of K-40 on brown algae was that3.72 x 10-2 Bq/g and gamma radioactivity of Tl-208 on fish as mentionedabove was that 1.35 x 10-2 Bq/g. All the peak spectrum gamma energy ofCs-137 do not detect with gamma counter, so there are not the radionuclide ofCs-137 in the samples. Spreading design of radioactivity which occur in thecoastal of Muria peninsula area for alpha radioactivity was found on kerapufish, beta radioactivities on sea water and gamma radioactivity on brownalgae and kerapu fish. (author)

175

The snakes and ladders of National Health Service management in England.  

Science.gov (United States)

This article explores managerial careers in the National Health Service (NHS) through the lens of talent management, particularly focusing on how managers view barriers (snakes) and facilitators (ladders) to career progression. There is a significant literature on enablers and barriers to career progression, but much of this focuses on specific groups such as black and minority ethnic and female workers, and there is relatively little material on the general workforce of the NHS. The research design is a mixed method quantitative (questionnaire) and qualitative (interview and focus group) approach consisting of a quasi-probability element that focuses on a maximum variety sample and a purposive element that seeks policy views at central and strategic health authority level, and examines talent management in high-performing NHS organisations. Ladders are identified as follows: volunteering, secondment, networking, mentoring, academic qualifications, development, good role models/managers and appraisal/personal development plan. Snakes are identified as managing expectations; identity and cognitive diversity; location; sector; NHS toxic and favouritism culture; poor talent spotting; credentialism; exclusive approach to talent; and sustainability. It concludes that while previous conceptual and empirical work is fairly clear on any ladders, it is less clear on snakes. PMID:24203889

Powell, Martin

2014-01-01

176

Fixed-location hydroacoustic monitoring designs for estimating fish passage using stratified random and systematic sampling  

International Nuclear Information System (INIS)

Five alternate sampling designs are compared using 15 d of 24-h continuous hydroacoustic data to identify the most favorable approach to fixed-location hydroacoustic monitoring of salmonid outmigrants. Four alternative aproaches to systematic sampling are compared among themselves and with stratified random sampling (STRS). Stratifying systematic sampling (STSYS) on a daily basis is found to reduce sampling error in multiday monitoring studies. Although sampling precision was predictable with varying levels of effort in STRS, neither magnitude nor direction of change in precision was predictable when effort was varied in systematic sampling (SYS). Furthermore, modifying systematic sampling to include replicated (e.g., nested) sampling (RSYS) is further shown to provide unbiased point and variance estimates as does STRS. Numerous short sampling intervals (e.g., 12 samples of 1-min duration per hour) must be monitored hourly using RSYS to provide efficient, unbiased point and interval estimates. For equal levels of effort, STRS outperformed all variations of SYS examined. Parametric approaches to confidence interval estimates are found to be superior to nonparametric interval estimates (i.e., bootstrap and jackknife) in estimating total fish passage. 10 refs., 1 fig., 8 tabs

177

Economic integration in the quality ladder model  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Realizamos aqui o mesmo tipo de "experimentos de integração" que em Rivera-Batiz e Romer (1991), desta vez no contexto de um modelo de "escada de qualidade", onde integração via comércio internacional não é suficiente para impedir redundância de esforços de P&D. Daí que um tipo adicional de integraç [...] ão seja analisada: "integração financeira". Adotamos como arcabouço o "modelo Schumpeteriano Simples" de Aghion e Howitt (2005), cuja tecnologia de inovação difere claramente daquelas concebidas em Rivera-Batiz e Romer (1991) por exibir retornos decrescentes de escala. Abstract in english Here we perform the same kind of "integration experiments" as in Rivera-Batiz and Romer (1991), this time in the context of a "quality ladder model", where international trade integration is not enough to prevent redundancy of R&D efforts. Thus a further kind of integration is analysed: "financial m [...] arket integration". We adopt as a setup the Simple Schumpeterian Model in Aghion and Howitt (2005), whose innovation technology differs sharply from the ones conceived by Rivera-Batiz and Romer in that it displays decreasing returns to scale.

Eduardo Correia de, Souza.

2008-12-01

178

Ladder Operators for Lamé Spheroconal Harmonic Polynomials  

Directory of Open Access Journals (Sweden)

Full Text Available Three sets of ladder operators in spheroconal coordinates and their respective actions on Lamé spheroconal harmonic polynomials are presented in this article. The polynomials are common eigenfunctions of the square of the angular momentum operator and of the asymmetry distribution Hamiltonian for the rotations of asymmetric molecules, in the body-fixed frame with principal axes. The first set of operators for Lamé polynomials of a given species and a fixed value of the square of the angular momentum raise and lower and lower and raise in complementary ways the quantum numbers $n_1$ and $n_2$ counting the respective nodal elliptical cones. The second set of operators consisting of the cartesian components $hat L_x$, $hat L_y$, $hat L_z$ of the angular momentum connect pairs of the four species of polynomials of a chosen kind and angular momentum. The third set of operators, the cartesian components $hat p_x$, $hat p_y$, $hat p_z$ of the linear momentum, connect pairs of the polynomials differing in one unit in their angular momentum and in their parities. Relationships among spheroconal harmonics at the levels of the three sets of operators are illustrated.

Ricardo Méndez-Fragoso

2012-10-01

179

Analysis of environmental issues related to small scale hydroelectric development. II. Design considerations for passing fish upstream around dams. Environmental Sciences Division Publication No. 1567  

Energy Technology Data Exchange (ETDEWEB)

The possible requirement of facilities to move migrating fish upstream around dams may be a factor in determining the feasibility of retrofitting small dams for hydroelectric generation. Basic design considerations are reported that should be evaluated on a site-specific basis if upstream fish passage facilities are being considered for a small scale hydroelectric project (defined as an existing dam that can be retrofitted to generate 25 MW or less). Information on general life history and geographic distribution of fish species that may require passage is presented. Biological factors important in the design of upstream passage facilities are discussed: gas bubble disease, fish swimming speed, oxygen consumption by fish, and diel and photo behavior. Three general types of facilities (fishways, fish locks, and fish lifts) appropriate for upstream fish passage at small scale hydroelectric projects are described, and size dimensions are presented. General design criteria for these facilities (including fish swimming ability and behavior) and general location of facilities at a site are discussed. Basic cost considerations for each type of passage facility, including unit cost, operation and maintenance costs, and costs for supplying attraction water, are indicated.

Hildebrand, S.G. (ed.)

1980-08-01

180

Walla Walla River Fish Passage Operations Project : Annual Progress Report October 2007 - September 2008.  

Energy Technology Data Exchange (ETDEWEB)

In the late 1990s, the Confederated Tribes of the Umatilla Indian Reservation, Oregon Department of Fish and Wildlife, and Washington Department of Fish and Wildlife, along with many other agencies, began implementing fisheries restoration activities in the Walla Walla Basin. An integral part of these efforts is to alleviate the inadequate fish migration conditions in the basin. Migration concerns are being addressed by removing diversion structures, constructing fish passage facilities, implementing minimum instream flow requirements, and providing trap and haul efforts when needed. The objective of the Walla Walla River Fish Passage Operations Project is to increase the survival of migrating adult and juvenile salmonids in the Walla Walla River basin. The project is responsible for coordinating operation and maintenance of ladders, screen sites, bypasses, trap facilities, and transportation equipment. In addition, the project provides technical input on passage and trapping facility design, operation, and criteria. Operation of the various passage facilities and passage criteria guidelines are outlined in an annual operations plan that the project develops. Beginning in March of 2007, two work elements from the Walla Walla Fish Passage Operations Project were transferred to other projects. The work element Enumeration of Adult Migration at Nursery Bridge Dam is now conducted under the Walla Walla Basin Natural Production Monitoring and Evaluation Project and the work element Provide Transportation Assistance is conducted under the Umatilla Satellite Facilities Operation and Maintenance Project. Details of these activities can be found in those project's respective annual reports.

Bronson, James P.; Duke, Bill; Loffink, Ken

2008-12-30

 
 
 
 
181

Estimación de reservas en una compañía aseguradora. Una aplicación en Excel del método Chain-Ladder y Bootstrap || Estimating the Reserves in Insurance Companies: An Excel Application of the Chain-Ladder Method and Bootstrap  

Directory of Open Access Journals (Sweden)

Full Text Available Las compañías aseguradoras deben calcular la cuantía de las reservas y la dotación de provisiones para hacer frente al pago de siniestros que o bien no han sido comunicados o bien no han sido cerrados. En este trabajo, se aplica el método Chain-Ladder para la estimación puntual de las reservas y, posteriormente, se recurre al bootstrap para obtener el error de muestreo y una estimación por intervalos. Dado que el cálculo de las reservas es un problema real al que se enfrentan las aseguradoras, su resolución es de gran interés para los estudiantes de Ciencias Actuariales. Para facilitar la comprensión y el seguimiento del proceso a desarrollar, los métodos Chain-Ladder y bootstrap se ejecutan paso a paso en una aplicación Excel diseñada ad hoc. || Insurance companies have to estimate reserves and provisions to cover the payment of either unreported claims or unsettled claims. In this paper, we apply the Chain-Ladder method to obtain a point estimate of reserves, and then we use the bootstrap technique to estimate the margin of error and the confidence interval of the reserves. Since estimating reserves is a real problem which insurance companies have to face, its solving has a special interest for students of Actuarial Sciences. To ease the understanding and monitoring the process, the Chain-Ladder method and bootstrap is run step by step by using an Excel application designed for that purpose.

Coll-Serrano, Vicente

2012-01-01

182

Hood River production program monitoring and evaluation. Report A: Hood River and Pelton Ladder evaluation studies. Annual report for 1996  

International Nuclear Information System (INIS)

In 1992, the Northwest Power Planning Council approved the Hood River and Pelton Ladder master plans within the framework of the Columbia River Basin Fish and Wildlife Program. The master plans define an approach for implementing a hatchery supplementation program in the Hood River subbasin. The hatchery program, as defined in the master plans, is called the Hood River Production Program (HRPP). The HRPP will be implemented at a reduced hatchery production level until (1) the construction of all proposed hatchery facilities has been completed and (2) numbers of returning wild jack and adult fish are sufficient to meet broodstock collection goals. It is anticipated that construction on the hatchery production facilities will be completed by the spring of 1998. The HRPP is jointly implemented by the Oregon Department of Fish and Wildlife (ODFW) and the Confederated Tribes of the Warm Springs (CTWS) Reservation

183

Certification and clinical ladder as the impetus for professional development.  

Science.gov (United States)

With today's healthcare challenges of nursing shortages and financial instability, it is imperative that healthcare organizations retain clinically competent nurses at the bedside. Professional development and recognition are key motivators to increase nursing job satisfaction, thus reducing shortages and turnover. Implementation of specialty certification and clinical advancement programs is of benefit to the public, employers, and nurses alike. Clinical ladder and Magnet recognition are often the impetus for specialty nursing certification in healthcare institutions. Clinical ladder history, purpose, models, perceptions, and satisfiers are discussed. Certification statistics, types, impetus, benefits, incentives, and barriers are highlighted, as well as a facility's innovative strategy to increase specialty certification. Certification and clinical ladder programs demonstrate commitment of healthcare organizations and nursing staff to provide high-quality care and professional nursing development, an investment that hospitals cannot afford to overlook. PMID:20019510

Watts, Misty D

2010-01-01

184

Fractal ladder models and power law wave equations.  

Science.gov (United States)

The ultrasonic attenuation coefficient in mammalian tissue is approximated by a frequency-dependent power law for frequencies less than 100 MHz. To describe this power law behavior in soft tissue, a hierarchical fractal network model is proposed. The viscoelastic and self-similar properties of tissue are captured by a constitutive equation based on a lumped parameter infinite-ladder topology involving alternating springs and dashpots. In the low-frequency limit, this ladder network yields a stress-strain constitutive equation with a time-fractional derivative. By combining this constitutive equation with linearized conservation principles and an adiabatic equation of state, a fractional partial differential equation that describes power law attenuation is derived. The resulting attenuation coefficient is a power law with exponent ranging between 1 and 2, while the phase velocity is in agreement with the Kramers-Kronig relations. The fractal ladder model is compared to published attenuation coefficient data, thus providing equivalent lumped parameters. PMID:19813816

Kelly, James F; McGough, Robert J

2009-10-01

185

NEW DESIGN FOR AIRLIFT PUMP USED IN FISH CULTURE TANKS WITH THE ENDANGERED RIO GRANDE SILVERY MINNOW (Hybognathus amarus  

Directory of Open Access Journals (Sweden)

Full Text Available This article describes an airlift pump used to produce a circular flow in a fish culture tank that does not attach to the tank. The design produces an airlift pump that does not swing back and forth or float upwards while in use. It is easy to build, inexpensive, and can be quickly installed and removed so that it does not interfere with sampling or harvest. The airlift pump was evaluated during a 30-d survival trial with the endangered Rio Grande silvery minnow (Hybognathus amarus in 2.44-m-diameter circular tanks (3,666 l. Because the fish is endangered, all new culture units must be evaluated in a survival trial. To be able to use a new 15-tank system, survival had to be evaluated in a random representation of three tanks. U.S. Fish and Wildlife Service, which regulates all activities with this endangered species, decided that permitted take (maximum permitted mortality was 60% for the survival trial; consequently, survival >40% in each tank would be considered successful. Two airlift pumps were placed in each tank. The two airlift pumps moved a mean±SD of 33.697±5.563 l/min; this produced total tank turnovers through the airlift pumps of 110.65±16.93 min. Water velocities were measured at nine locations in the tanks. Water velocities were 0.0-0.04 m/sec. Dissolved oxygen concentration never went below 6.30 mg/l. The airlift pumps operated flawlessly and required no maintenance. They produced water velocities preferred by the fish and helped keep dissolved oxygen concentration above the permitted minimum (5 mg/l. The airlift pumps will be used in future fish culture activities in these and other tanks. Survival in the three tanks was 78%, 94% and 96%; overall survival was 89.3%. Because take (10.7% was under the permitted level (60%, the trial was successful.

Alison M. Hutson

2012-10-01

186

Identification of topologically different valence bond states in spin ladders  

CERN Document Server

We discuss relation between three different methods to identify topologically distinct short-range valence-bond ground states in spin-$\\frac12$ two-leg ladders: the string order parameters, the level-crossing method, and the ground-state expectation value of the twist operator. For this purpose we reexamine a phase transition in the frustrated spin ladder. We propose a proper bosonization of the string order parameters. Then, these three methods are shown to be equivalent reflecting the $Z_2\\times Z_2$ symmetry breaking of the order and the disorder fields of the two-dimensional Ising model.

Nakamura, M

2003-01-01

187

Magnetic properties and quantum entanglement on decorated zigzag ladder  

International Nuclear Information System (INIS)

Magnetic properties and quantum entanglement of Heisenberg model with two-, three- and four- site exchange interactions on zigzag ladder are studied. Magnetic properties and concurrence (measure of quantum entanglement) are analyzed by means of variational mean-field-like treatment based on the Gibbs-Bogoliubov inequality. The magnetization plateau and second-order phase transition were obtained. A comparison of the entanglement and magnetic behavior for zigzag ladder is made. We have found that in the antiferromagnetic region the behavior of the concurrence coincides with the magnetization one

188

Notebook Positioning by Perceptual Map and Laddering Method  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this applied paper is to determine positioning of laptops by perceptual map and laddering method. Data collection method was survey using questionnaire. First by using the views of computer experts of selected brands, including Sony, Acer, Asus, Dell and Msi, 5 among 20 attributes, which were considered more important, were selected through application of factor analysis technique. Then, after classification of these features by laddering technique, they were analyzed by using another questionnaire to determine the position of each brand in the perceptual map. We try to show factors and laptop brands position with regard two factors of price and quality in the resulted perceptual map.

Mehdi Zaribaf

2012-01-01

189

A snakes and ladders representation of stock prices and returns  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Snakes and ladders is an ancient Indian game of chance that offers amusement as well as a metaphor for life’s many ups and downs. Games offer useful and fun ways of conveying ideas as well as solution techniques and this game has considerable mathematical tractability. This note shows how snakes and ladders can be used to represent the ups and downs of share ownership and solve for fair values of a multistage project that pays fixed dividends at uncertain completion times and has random ret...

Gager, P.; Shackleton, M. B.

2009-01-01

190

DUNDRUM Restriction-Intrusion of Liberty Ladders (DRILL) Audit Toolkit  

LENUS (Irish Health Repository)

This series of rating \\'ladders\\' is intended to allow a quantitative and qualitative analysis of the use of restrictive and intrusive interventions as part of the therapeutic management of violence and aggression in psychiatric hospital settings. This is an evolving handbook. The ladders are currently organised to facilitate a behavioural analysis. Context, antecedents, behaviour, interventions, consequences are conceptualised as a series of events organised in temporal sequence so that causes, interactions and effects can be considered. The complexity of analysis possible is limited by the statistical power of the numbers of cases and events available. \\r\

Kennedy, Harry G

2011-09-01

191

The new reconstructive ladder: modifications to the traditional model.  

Science.gov (United States)

The traditional reconstructive ladder has withstood the test of time, serving as a thought paradigm to guide surgeons in choosing their method of wound closure for an assortment of defects. Advances in anatomical understanding and technological innovations have improved our ability to achieve definitive closure in a wide variety of patients. In this article, the older construct is updated to reflect the use of negative-pressure wound therapy and dermal matrices. Perforator flap concepts are also discussed in terms of their inclusion as a rung on the ladder. PMID:21200292

Janis, Jeffrey E; Kwon, Robert K; Attinger, Christopher E

2011-01-01

192

Walla Walla River Fish Passage Operations Program, 2003-2004 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

In the late 1990s, the Confederated Tribes of the Umatilla Indian Reservation, Oregon Department of Fish and Wildlife, and Washington Department of Fish and Wildlife, along with many other agencies, began implementing fisheries restoration activities in the Walla Walla Basin. An integral part of these efforts is to alleviate the inadequate fish migration conditions in the basin. The migration concerns are being addressed by removing diversion structures, constructing fish passage facilities, implementing minimum instream flow requirements, and providing trap and haul efforts when needed. The objective of the Walla Walla River Fish Passage Operations Project is to increase the survival of migrating adult and juvenile salmonids in the Walla Walla River basin. The project is responsible for coordinating operation and maintenance of ladders, screen sites, bypasses, trap facilities, and transportation equipment. In addition, the project provides technical input on passage criteria and passage and trapping facility design and operation. Operation of the various passage facilities and passage criteria guidelines are outlined in an annual operations plan that the project develops. During the 2003-2004 project year, there were 379 adult summer steelhead (Oncorhynchus mykiss), 36 adult bull trout (Salvelinus confluentus); 108 adult and 3 jack spring chinook (O. tshawytscha) enumerated at the Nursery Bridge Dam fishway video counting window between December 21, 2003, and June 30, 2004. Summer steelhead and spring chinook were observed moving upstream while bull trout were observed moving both upstream and downstream of the facility. In addition, the old ladder trap was operated by the WWBNPME project in order to radio tag spring chinook adults. A total of 2 adult summer steelhead, 4 bull trout, and 23 adult spring chinook were enumerated at the west ladder at Nursery Bridge Dam during the trapping operations between May 6 and May 23, 2004. Operation of the Little Walla Walla River juvenile trap for trap and haul purposes was not necessary this year. The project transported adult spring chinook from Threemile Dam to the South Fork Walla Walla Brood Holding Facility. A total of 239 spring chinook were outplanted in August for natural spawning in the basin.

Bronson, James P. (Confederated Tribes of the Umatilla Indian Reservation, Department of Natural Resources, Pendleton, OR)

2004-12-01

193

On the basis number of the composition of different ladders with some graphs  

Directory of Open Access Journals (Sweden)

Full Text Available The basis number b(G of a graph G is defined to be the least integer k such that G has a k-fold basis for its cycle space. In this paper, we investigate the basis number of the composition of paths and cycles with ladders, circular ladders, and Möbius ladders.

Maref Y. Alzoubi

2005-08-01

194

9 CFR 93.911 - Ports designated for the importation of live VHS-regulated fish species.  

Science.gov (United States)

...the importation of live VHS-regulated fish species. 93.911 Section 93.911...IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN ANIMAL, BIRD... General Provisions for Vhs-Regulated Fish Species § 93.911 Ports...

2010-01-01

195

Color conductivity and ladder summation in hot QCD  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The color conductivity is computed at leading logarithmic order using a Kubo formula. We show how to sum an infinite series of planar ladder diagrams, assuming some approximations based on the dominance of soft scattering processes between hard particles in the plasma. The result agrees with the one obtained previously from a kinetical approach.

Resco, J. M. Martinez; Basagoiti, M. A. Valle

2000-01-01

196

Reading Ladders for Human Relations. 5th Edition.  

Science.gov (United States)

Updated through the help of teachers, librarians, and other specialists, the book aims at advancing the cause of better human relations through literature, especially drama and fiction. The reading ladders include: 1) Creating a Positive Self-Image, recognizing one's strengths and weaknesses, growing into maturity and accepting oneself,…

Reid, Virginia M., Ed.

197

Magnetization Plateau of an S=1 Frustrated Spin Ladder  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the magnetization plateau at 1/4 of the saturation magnetization of the S=1 antiferromagnetic spin ladder both analytically and numerically, with the aim of explaining recent experimental results on BIP-TENO by Goto et al. We propose two mechanisms for the plateau formation and clarify the plateau phase diagram on the plane of the coupling constants between spins.

Okamoto, Kiyomi; Okazaki, Nobuhisa; Sakai, To?ru

2000-01-01

198

29 CFR 1918.24 - Fixed and portable ladders.  

Science.gov (United States)

...side rails; (iii) Missing or loose bolts, rivets or fastenings; (iv) Defective ropes; or (v) Any other structural...additional length. (8) Single rail ladders (i.e. made by fastening rungs or devices across a single rail) shall not be...

2010-07-01

199

Jacob's ladders and some new consequences from A. Selberg's formula  

CERN Document Server

It is proved in this paper that the Jacob's ladders together with the A. Selberg's classical formula (1942) lead to a new kind of formulae for some short trigonometric sums. These formulae cannot be obtained in the classical theory of A. Selberg, and all the less, in the theories of Balasubramanian, Heath-Brown and Ivic.

Moser, Jan

2010-01-01

200

Superconductivity and magnetic properties of spin-ladder compounds  

International Nuclear Information System (INIS)

A review is given of the structural, magnetic and transport studies on two-leg spin-ladder (M2Cu2O3)m(CuO2)n systems (where M are divalent or/and trivalent cations). The crystals belonging to these systems consist of two interpenetrated subsystems. The first subsystem [M2Cu2O3] is composed of (Cu2O3) two-leg ladder planes and M ions coordinated to them. The second subsystem consists of CuO2 1D-chains. In these materials, the superconductivity was discovered for m/n = 1/1, 5/7, 7/10. The intrinsic and extrinsic superconducting properties of spin-ladder systems are presented and discussed in detail. The important role played by the hole transfer from CuO2 planes to the spin-ladder planes is stressed. It is shown that the superconductivity in this new family of high-temperature superconductors should be described as an extreme type II limit. (orig.)

 
 
 
 
201

Career Ladder Policy for Teachers: The Case of Ghana  

Science.gov (United States)

In 1984 the Ministry of Education in Ghana introduced a career ladder policy for teachers. While reformers believe that this has improved the condition of the teaching profession, the net gains of the policy remain deceptive. There has even been a reduction in some of the benefits that teachers used to enjoy in the single salary scheme in the…

Osei, George M.

2008-01-01

202

PLUME collaboration: Ultra-light ladders for linear collider vertex detector  

Energy Technology Data Exchange (ETDEWEB)

The PLUME (Pixelated Ladder with Ultra-Low Material Embedding) Collaboration is developing ultra-light ladders for the vertex detector for a future linear collider. The double-sided ladder will integrate the sensors, readout infrastructure and mechanical supports with the aim of total material budget of 0.3% of radiation length. The requirement of as light as possible construction is driven by physics, in particular by measurements requiring determination of the quark charge sign. The first prototype ladders were prepared and tested in the beam. The alignment issues for the ladders will be tested within the AIDA (Advanced European Infrastructures for Detectors at Accelerators) EU FP7 project.

Nomerotski, A., E-mail: A.Nomerotski@physics.ox.ac.uk [University of Oxford, Particle Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Bachynska, O. [DESY Hamburg, Notkestr. 85, D-22607 Hamburg (Germany); Baudot, J.; Chon-Sen, N.; Claus, G.; De Masi, R. [IPHC/IN2P3/CNRS and Universite de Strasbourg, Strasbourg (France); Deveaux, M. [IK-Frankfurt, Goethe-Universitaet, Frankfurt am Main (Germany); Dulinski, W. [IPHC/IN2P3/CNRS and Universite de Strasbourg, Strasbourg (France); Gauld, R. [University of Oxford, Particle Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Goffe, M. [IPHC/IN2P3/CNRS and Universite de Strasbourg, Strasbourg (France); Goldstein, J. [University of Bristol, Tyndall Avenue, Bristol BS8 1TL (United Kingdom); Gregor, I.-M. [DESY Hamburg, Notkestr. 85, D-22607 Hamburg (Germany); Hu-Guo, Ch.; Imhoff, M. [IPHC/IN2P3/CNRS and Universite de Strasbourg, Strasbourg (France); Koetz, U. [DESY Hamburg, Notkestr. 85, D-22607 Hamburg (Germany); Lau, W. [University of Oxford, Particle Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom); Muntz, C. [IK-Frankfurt, Goethe-Universitaet, Frankfurt am Main (Germany); Santos, C. [IPHC/IN2P3/CNRS and Universite de Strasbourg, Strasbourg (France); Schrader, C. [IK-Frankfurt, Goethe-Universitaet, Frankfurt am Main (Germany); Specht, M. [IPHC/IN2P3/CNRS and Universite de Strasbourg, Strasbourg (France); and others

2011-09-11

203

Determination of selenium in fish from designated critical habitat of the Gunnison River, Colorado, summer 2011  

Science.gov (United States)

This report presents results for the summer 2011 sampling of muscle plugs from common carps (Cyprinus Linnaeus), roundtail chub (Gila robusta), and bonytail chub (Gila elegans) inhabiting critical habitat in the Gunnison River in Western Colorado. Total selenium in fish muscle plugs was determined by instrumental neutron activation analysis. Total selenium concentrations (range and mean ± standard deviation) in micrograms per gram dry weight for each species were as follows: common carp: 8.5 to 35, 13 ± 7.8; roundtail chub: 5.5 to 11.2, 7.3 ± 1.6; bonytail chub: 0.8 to 8.6, 3.9 ± 4.2. Selenium concentrations in muscle plugs from 4 out of 15 roundtail chub, all 15 common carp, and 2 out of 5 bonytail chub exceeded the 8 micrograms per gram dry weight toxicity guideline for selenium in fish muscle tissue.

May, Thomas W.; Walther, Michael J.

2012-01-01

204

Effects of foot placement, hand positioning, age and climbing biodynamics on ladder slip outcomes.  

Science.gov (United States)

Ladder falls frequently cause severe injuries; yet the factors that influence ladder slips/falls are not well understood. This study aimed to quantify (1) the effects of restricted foot placement, hand positioning, climbing direction and age on slip outcomes, and (2) differences in climbing styles leading to slips versus styles leading to non-slips. Thirty-two occupational ladder users from three age groups (18-24, 25-44 and 45-64 years) were unexpectedly slipped climbing a vertical ladder, while being assigned to different foot placement conditions (unrestricted vs. restricted toe clearance) and different hand positions (rails vs. rungs). Constraining foot placement increased the climber's likelihood of slipping (p positioning were found in styles leading to a slip. Maintaining sufficient toe clearance and targeting ladder safety training to younger and older workers may reduce ladder falls. Practitioner Summary: Ladder falls frequently cause severe occupational fall injuries. This study aims to identify safer ladder climbing techniques and individuals at risk of falling. The results suggest that ladders with unrestricted toe clearance and ladder climbing training programmes, particularly for younger and older workers, may reduce ladder slipping risk. PMID:25116116

Pliner, Erika M; Campbell-Kyureghyan, Naira H; Beschorner, Kurt E

2014-11-01

205

Versatile design and synthesis platform for visualizing genomes with Oligopaint FISH probes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A host of observations demonstrating the relationship between nuclear architecture and processes such as gene expression have led to a number of new technologies for interrogating chromosome positioning. Whereas some of these technologies reconstruct intermolecular interactions, others have enhanced our ability to visualize chromosomes in situ. Here, we describe an oligonucleotide- and PCR-based strategy for fluorescence in situ hybridization (FISH) and a bioinformatic platform that enables t...

Beliveau, Brian J.; Joyce, Eric F.; Apostolopoulos, Nicholas; Yilmaz, Feyza; Fonseka, Chamith Y.; Mccole, Ruth B.; Chang, Yiming; Li, Jin Billy; Senaratne, Tharanga Niroshini; Williams, Benjamin R.; Rouillard, Jean-marie; Wu, Chao-ting

2012-01-01

206

The Effects of Laddering and Spinning in Underwriter Manipulation of IPOs  

Directory of Open Access Journals (Sweden)

Full Text Available Using a unique and larger sample of companies from going public from 1998- 2000 classified by both spinning and laddering manipulation, we are able to disentangle the effects of laddering and spinning and find that much of the underpricing during the internet bubble was due to laddering rather than spin-ning. In fact, we find that a laddered IPO is expected to be underpriced by 110% compared to a non-laddered IPO. The effects of spinning are insig-nificant once laddering is simultaneously considered. Our study lends further support to the laddering theory of Aggarwal et al. (2006 as a reason for IPO underpricing during the internet bubble.

Ludwig Chincarini

2012-09-01

207

Means – End Chain Theory and Laddering Technique: Applications in Consumer Behavior Research  

Directory of Open Access Journals (Sweden)

Full Text Available Means – end chain (MEC theory and laddering technique uncovers the decision making process of consumers related to marketing offerings such as goods, services and experiences in a cognitive approach from a consumer perspective view which are popularly used approaches in marketing context. The purpose of the study is to discusss and present the laddering techique to Turkish literature, which is a frequently used qualitative research method in consumer behavior, both with related theoretical structure and practice. With this purpose, the overview of the literature within the frame of means – end chain theory, practices in consumer behavior, laddering technique, data collection, data analyze and interperation steps, limits of the laddering technique and alternatives of soft laddering (hard laddering is discussed. Laddering technique among with alternative data collection tools are anticipated Turkish researchers’ interest.

Ayca Kangal

2013-04-01

208

Fish Allergy  

Science.gov (United States)

About Fish Allergy A fish allergy is not exactly the same as a seafood allergy. Seafood includes both fish (like tuna ... alert bracelet. Continue What Happens in a Fish Allergy When someone is allergic to fish, the body's ...

209

The evolution of cranial design, diet, and feeding mechanisms in batoid fishes.  

Science.gov (United States)

The batoid fishes (electric rays, sawfishes, skates, guitarfishes, and stingrays) are a trophically and morphologically diverse clade in which the observed range of diets is a product of a feeding mechanism with few parts and therefore a limited number of functional interactions. This system allows an intriguing comparison to the complex network of associations in the feeding apparatus of bony fishes and an anatomically simple framework for investigations of the mechanisms underlying the evolution of functional and phenotypic diversity. We quantified morphology from reconstructed CT scans of 40 batoid species, representing more than half of the extant genera. We used pairwise comparisons to evaluate the extent of coevolution among components of the feeding apparatus and among morphologies and diets. These relationships were then used to predict diets in poorly studied taxa and in a reconstruction of the batoid ancestor. Although functionally there are fewer examples of convergence in the batoid feeding mechanism than in bony fishes, our data show multiple evolutions of similar dietary compositions underlain by a broad morphological diversity. Elements of the feeding apparatus evolved independently of one another, suggesting that decoupling components of the head skeleton created separate but interacting evolutionary modules that allowed trophic diversification. Our data imply that food habits exhibit strong independent and convergent evolution and that suites of morphologies are associated with certain diets; however, lack of behavioral data for this clade, and one example of divergent diets underlain by convergent morphology, caution against the assumption of simplistic relationships between form and function. We therefore urge future work to ground truth our study by testing the functional, dietary and evolutionary hypotheses suggested by our data. PMID:21672821

Dean, Mason N; Bizzarro, Joseph J; Summers, Adam P

2007-07-01

210

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT...OCCUPATIONAL SAFETY AND HEALTH STANDARDS Walking-Working...will cause the maximum stress in the structural member...Design stresses. Design stresses for wood components...to have no deleterious effect one upon the...

2010-07-01

211

New Design of Crypto-Based Pseudo random number generator (CBPRNG using BLOW FISH cipher  

Directory of Open Access Journals (Sweden)

Full Text Available Random Number Generators (RNGs are an important building block for algorithms and protocols in cryptography. Random number generation is used in a wide variety of cryptographic operations, such as key generation and challenge/response protocols. A random number generator outputs a sequence of 0s and 1s such that at any position, the next bit cannot be expected on the previous bits. However, true random number produces non- deterministic output since if the same random generator is run twice, identical results are not received. Thus we go for pseudo random number generator that is deterministic device because if this random number generator is run twice or more, it gives same results. Our paper presents new crypto based pseudorandom number generator. It uses BLOW FISH ciphers and the Cipher-Block chaining (CBC mode that uses three stages of the block chaining. The plain text for each stage comes from the output of the first BLOW FISH, which uses the 64-Bit date and time as the plain text. CBPRNG creates three 64-bit random numbers, the first and the second are concatenated to create a 128-random number and the third is used as next initial vector (IV for CBPRNG. Our Crypto-Based Pseudo-random Number Generator produces a sequence of bits that has arandom looking distribution. This new generator helps to develop huge range cryptographic applications to increase the system security. A number of applications such as financial security applications and Pretty Good Privacy (PGP use this technique.

T.Chalama Reddy

2013-06-01

212

Action–angle variables, ladder operators and coherent states  

International Nuclear Information System (INIS)

This Letter is devoted to the building of coherent states from arguments based on classical action–angle variables. First, we show how these classical variables are associated to an algebraic structure in terms of Poisson brackets. In the quantum context these considerations are implemented by ladder type operators and a structure known as spectrum generating algebra. All this allows to generate coherent states and thereby the correspondence of classical–quantum properties by means of the aforementioned underlying structure. This approach is illustrated with the example of the one-dimensional Pöschl–Teller potential system. -- Highlights: ? We study the building of coherent states from classical action–angle variables arguments. ? The classical variables are associated to an algebraic structure in terms of Poisson brackets. ? In the quantum context these considerations are implemented by ladder type operators. ? All this allows to formulate coherent states and the correspondence of classical–quantum properties.

213

Action–angle variables, ladder operators and coherent states  

Energy Technology Data Exchange (ETDEWEB)

This Letter is devoted to the building of coherent states from arguments based on classical action–angle variables. First, we show how these classical variables are associated to an algebraic structure in terms of Poisson brackets. In the quantum context these considerations are implemented by ladder type operators and a structure known as spectrum generating algebra. All this allows to generate coherent states and thereby the correspondence of classical–quantum properties by means of the aforementioned underlying structure. This approach is illustrated with the example of the one-dimensional Pöschl–Teller potential system. -- Highlights: ? We study the building of coherent states from classical action–angle variables arguments. ? The classical variables are associated to an algebraic structure in terms of Poisson brackets. ? In the quantum context these considerations are implemented by ladder type operators. ? All this allows to formulate coherent states and the correspondence of classical–quantum properties.

Campoamor-Stursberg, R., E-mail: rutwigcs@gmail.com [Departamento de Geometría y Topología, Universidad Complutense de Madrid, 28040 Madrid (Spain); Gadella, M., E-mail: manuelgadella1@gmail.com [Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47071 Valladolid (Spain); Kuru, ?., E-mail: kuru@science.ankara.edu.tr [Department of Physics, Faculty of Science, Ankara University, 06100 Ankara (Turkey); Negro, J., E-mail: jnegro@fta.uva.es [Departamento de Física Teórica, Atómica y Óptica, Universidad de Valladolid, 47071 Valladolid (Spain)

2012-07-30

214

Daughters of Bilitis and the Ladder that Teetered.  

Science.gov (United States)

ABSTRACT This article traces the economic history of the Daughters of Bilitis, the first national Lesbian organization, and its periodical The Ladder. Besides membership, subscriptions and fundraisers were monetary donations and in-kind "gifts" from businesses. Staff labor was volunteer. Compensation for authors was DOB's guarantee of full rights to their own work. Funding was precarious until an anonymous donor came to the rescue. Funds were funneled through a member/friend who singularly decided what project to back. Officers of the organization were not privy to an overall plan, nor any accounting of how the funds were spent. In the end, secrecy was the undoing of DOB as a national organization and the demise of The Ladder as well. PMID:24802830

Martin, D; Lyon, P

2001-01-01

215

Experimentally testing Bell's theorem based on Hardy's nonlocal ladder proofs  

Science.gov (United States)

Bell's theorem argues the existence of quantum nonlocality which goes basically against the hidden variable theory (HVT). Many experiments have been done via testing the violations of Bell's inequalities to statistically verify the Bell's theorem. Alternatively, by testing the Hardy's ladder proofs we experimentally demonstrate the deterministic violation of HVT and thus confirm the quantum nonlocality. Our tests are implemented with non-maximal entangled photon pairs generated by spontaneous parametric down conversions (SPDCs). We show that the degree freedom of photon entanglement could be significantly enhanced by using interference filters. As a consequence, the Hardy's ladder proofs could be tested and Bell's theorem is verified robustly. The probability of violating the locality reach to 41.9%, which is close to the expectably ideal value 46.4% for the photon pairs with degree of entanglement ? = 0.93. The higher violating probability is possible by further optimizing the experimental parameters.

Guo, WeiJie; Fan, DaiHe; Wei, LianFu

2014-09-01

216

Broken time-reversal symmetry in strongly correlated ladder structures  

CERN Document Server

We provide, for the first time, in a doped strongly correlated system (two-leg ladder), a controlled theoretical demonstration of the existence of a state in which long-ranged circulating currents are arranged in a staggered pattern. The method used is the highly accurate density matrix renormalization group technique. This brings us closer to recent proposals that this order is realized in the enigmatic pseudogap phase of the cuprate high temperature superconductors.

Schollwöck, U; Fjaerestad, J O; Marston, J B; Troyer, M; Chakravarty, Sudip

2003-01-01

217

Speeding up the Training of Lattice-Ladder Multilayer Perceptrons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A lattice-ladder multilayer perceptron (LLMLP) is an appealing structure for advanced signal processing in a sense that it is nonlinear, possesses infinite impulse response and stability monitoring of it during training is simple. However, even moderate implementation of LLMLP training hinders the fact that a lot of storage and computation power must be allocated. In this paper we deal with the problem of computational efficiency of LLMLP training algorithms that are based on computation of g...

Navakauskas, Dalius

2002-01-01

218

Single-particle potential from resummed ladder diagrams  

Energy Technology Data Exchange (ETDEWEB)

A recent work on the resummation of fermionic in-medium ladder diagrams to all orders is extended by calculating the complex single-particle potential U(p, k{sub f}) + i W(p, k{sub f}) p > k{sub f}. The on-shell single-particle potential is constructed by means of a complex-valued in-medium loop that includes corrections from a test particle of momentum vector p added to the filled Fermi sea. The single-particle potential U(k{sub f}, k{sub f}) at the Fermi surface as obtained from the resummation of the combined particle and hole ladder diagrams is shown to satisfy the Hugenholtz-Van-Hove theorem. The perturbative contributions at various orders a{sup n} in the scattering length are deduced and checked against the known analytical results at order a{sup 1} and a{sup 2}. The limit a {yields} {infinity} is studied as a special case and a strong momentum dependence of the real (and imaginary) single-particle potential is found. This feature indicates an instability against a phase transition to a state with an empty shell inside the Fermi sphere such that the density gets reduced by about 5%. The imaginary single-particle potential vanishes linearly at the Fermi surface. For comparison, the same analysis is performed for the resummed particle-particle ladder diagrams alone. In this truncation an instability for hole excitations near the Fermi surface is found at strong coupling. For the set of particle-hole ring diagrams the single-particle potential is calculated as well. Furthermore, the resummation of in-medium ladder diagrams to all orders is studied for a two-dimensional Fermi gas with a short-range two-body contact interaction. (orig.)

Kaiser, N. [Technische Universitaet Muenchen, Physik-Department T39, Garching (Germany)

2013-11-15

219

Correlations in Quantum Spin Ladders with Site and Bond Dilution  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We investigate the effects of quenched disorder, in the form of site and bond dilution, on the physics of the $S=1/2$ antiferromagnetic Heisenberg model on even-leg ladders. Site dilution is found to prune rung singlets and thus create localized moments which interact via a random, unfrustrated network of effective couplings, realizing a random-exchange Heisenberg model (REHM) in one spatial dimension. This system exhibits a power-law diverging correlation length as the temp...

Trinh, Kien; Haas, Stephan; Yu, Rong; Roscilde, Tommaso

2011-01-01

220

Snakes and ladders: localized solutions of plane Couette flow  

CERN Document Server

We demonstrate the existence of a large number of exact solutions of plane Couette flow, which share the topology of known periodic solutions but are localized in space. Solutions of different size are organized in a snakes-and-ladders structure strikingly similar to that observed for simpler pattern-forming PDE systems. These new solutions are a step towards extending the dynamical systems view of transitional turbulence to spatially extended flows.

Schneider, Tobias M; Burke, John

2009-01-01

 
 
 
 
221

Field-Induced Gaps in the Frustrated Spin Ladder  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study the magnetization process of the $S=1/2$ antiferromagnetic spin ladder in the presence of the second and the third-neighbor couplings which lead to frustration with the typical nearest-neighbor coupling. We use degenerate perturbation theory and level spectroscopy analysis of the numerical diagonalization data of the Hamiltonian for finite systems. We find two kinds of plateaux at half the saturation moment in the magnetization curve. One is mainly due to the second...

Okazaki, Nobuhisa; Okamoto, Kiyomi; Sakai, Toru

2000-01-01

222

Climbing the ladder from novice to expert plastic surgeon.  

Science.gov (United States)

This article reviews the nature of novice and expert thinking and shows how pattern recognition is a key distinction between the two. The article also discusses the ladder that learners climb as they move from medical student to senior staff surgeon and suggests ways of viewing surgical trainees as they progress through the process so that learning activities can be adopted that best fit them. PMID:22418717

Weber, Robert A; Aretz, H Thomas

2012-07-01

223

Chirping a two-photon transition in a multistate ladder  

International Nuclear Information System (INIS)

We consider a two-photon transition in a specific ladder system driven by a chirped laser pulse. In the weak field limit, we find that the excited state probability amplitude arises due to interference of multiple quantum paths which are weighted by quadratic phase factors. The excited state population has the form of a Gauss sum which plays a prominent role in number theory

224

The search for competing charge orders in frustrated ladder systems  

International Nuclear Information System (INIS)

A recent study revealed the dynamics of the charge sector of a one-dimensional quarter- filled electronic system with extended Hubbard interactions to be that of an effective pseudospin transverse-field Ising model (TFIM) in the strong coupling limit. With the twin motivations of studying the co-existing charge and spin order found in strongly correlated chain systems and the effects of inter-chain couplings, we investigate the phase diagram of coupled effective (TFIM) systems. A bosonisation and RG analysis for a two-leg TFIM ladder yields a rich phase diagram showing Wigner/Peierls charge order and Neel/dimer spin order. In a broad parameter regime, the orbital antiferromagnetic phase is found to be stable. An intermediate gapless phase of finite width is found to lie in between two charge-ordered gapped phases. Kosterlitz-Thouless transitions are found to lead from the gapless phase to either of the charge-ordered phases. Low energy effective Hamiltonian analyses of a strongly coupled 2-chain ladder system confirm a phase diagram with in-chain CO, rung-dimer, and orbital antiferromagnetic ordered phases with varying interchain couplings as well as superconductivity upon hole-doping. Our work is potentially relevant for a unified description of a class of strongly correlated, quarter-filled chain and ladder systems. (autor)

225

"Why caipirinha?"- the online via chat laddering technique CAN answer  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english As customers are becoming increasingly connected to the internet, this means that they are available for online interviews, thus opening up a space for investigating research methods, especially qualitative research, in an attempt to identify how to adapt data collecting instruments to the so-called [...] "connected customer era". In this context, the focus of this article is on the application viability analysis of the laddering technique used online and in real-time chat by asking the following question: "Why caipirinha?". Conducting online in-depth interviews through the MSN Messenger and Skype (the most commonly used chat tools in Brazil), 23 attributes, 22 consequences and 13 values were identified, resulting in 133 ladders, 71 of which reached the value level. Along with friends/mates, Integration, Entertainment and Fun, in addition to Alcohol, Insouciance/ relaxation and Pleasure constitute the most frequent ladders. Concerning the application itself, the participants gave positive feedback, even though some of them did not feel satisfied because they became tired. Convenience, objectivity, disinhibition, easy scheduling and flexibility were identified. The viability of online in-depth interviewing via real-time chats was confirmed, raising the question of the possibility of it achieving other qualitative research techniques.

Bruno, Bordeaux-Rego; Fernanda, Nedwed-Machado; Marta Olivia Rovedder de, Oliveira; Denise Avancini, Alves; Luiz Antonio, Slongo.

2011-06-01

226

“Why Caipirinha?”- The Online via Chat Laddering Technique CAN Answer  

Directory of Open Access Journals (Sweden)

Full Text Available As customers are becoming increasingly connected to the internet, this means that they are available for online interviews, thus opening up a space for investigating research methods, especially qualitative research, in an attempt to identify how to adapt data collecting instruments to the so-called “connected customer era”. In this context, the focus of this article is on the application viability analysis of the laddering technique used online and in real-time chat by asking the following question: “Why caipirinha?”. Conducting online in-depth interviews through the MSN Messenger and Skype (the most commonly used chat tools in Brazil, 23 attributes, 22 consequences and 13 values were identified, resulting in 133 ladders, 71 of which reached the value level. Along with friends/mates, Integration, Entertainment and Fun, in addition to Alcohol, Insouciance/ relaxation and Pleasure constitute the most frequent ladders. Concerning the application itself, the participants gave positive feedback, even though some of them did not feel satisfied because they became tired. Convenience, objectivity, disinhibition, easy scheduling and flexibility were identified. The viability of online in-depth interviewing via real-time chats was confirmed, raising the question of the possibility of it achieving other qualitative research techniques.

Bruno Bordeaux-Rego

2011-04-01

227

"Why caipirinha?"- the online via chat laddering technique CAN answer  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english As customers are becoming increasingly connected to the internet, this means that they are available for online interviews, thus opening up a space for investigating research methods, especially qualitative research, in an attempt to identify how to adapt data collecting instruments to the so-called [...] "connected customer era". In this context, the focus of this article is on the application viability analysis of the laddering technique used online and in real-time chat by asking the following question: "Why caipirinha?". Conducting online in-depth interviews through the MSN Messenger and Skype (the most commonly used chat tools in Brazil), 23 attributes, 22 consequences and 13 values were identified, resulting in 133 ladders, 71 of which reached the value level. Along with friends/mates, Integration, Entertainment and Fun, in addition to Alcohol, Insouciance/ relaxation and Pleasure constitute the most frequent ladders. Concerning the application itself, the participants gave positive feedback, even though some of them did not feel satisfied because they became tired. Convenience, objectivity, disinhibition, easy scheduling and flexibility were identified. The viability of online in-depth interviewing via real-time chats was confirmed, raising the question of the possibility of it achieving other qualitative research techniques.

Bruno, Bordeaux-Rego; Fernanda, Nedwed-Machado; Marta Olivia Rovedder de, Oliveira; Denise Avancini, Alves; Luiz Antonio, Slongo.

228

Calculation of tensor susceptibility beyond rainbow-ladder approximation  

International Nuclear Information System (INIS)

In this paper, we extend the calculation of tensor vacuum susceptibility in the rainbow-ladder approximation of the Dyson-Schwinger (DS) approach in Shi et al. (Phys Lett B 639:248, 2006) to that of employing the Ball-Chiu (BC) vertex. The dressing effect of the quark-gluon vertex on the tensor vacuum susceptibility is investigated. Our results show that compared with its rainbow-ladder approximation value, the tensor vacuum susceptibility obtained in the BC vertex approximation is reduced by about 10%. This shows that the dressing effect of the quark-gluon vertex is not large in the calculation of the tensor vacuum susceptibility in the DS approach. In this paper we also demonstrate that the tensor vacuum susceptibility can be used to demarcate the domain of coupling strength within a theory upon which chiral symmetry is dynamically broken. For couplings below the associated critical value and in the absence of confinement, the tensor vacuum susceptibility remains zero. This situation changes until the interaction strength is larger than a critical point. It is found that the critical point in the rainbow-ladder approximation is larger than that in the BC vertex approximation. This is easy to understand, because the effect of the BC vertex itself amounts to enhancing the interaction strength. (author)

229

Versatile design and synthesis platform for visualizing genomes with Oligopaint FISH probes.  

Science.gov (United States)

A host of observations demonstrating the relationship between nuclear architecture and processes such as gene expression have led to a number of new technologies for interrogating chromosome positioning. Whereas some of these technologies reconstruct intermolecular interactions, others have enhanced our ability to visualize chromosomes in situ. Here, we describe an oligonucleotide- and PCR-based strategy for fluorescence in situ hybridization (FISH) and a bioinformatic platform that enables this technology to be extended to any organism whose genome has been sequenced. The oligonucleotide probes are renewable, highly efficient, and able to robustly label chromosomes in cell culture, fixed tissues, and metaphase spreads. Our method gives researchers precise control over the sequences they target and allows for single and multicolor imaging of regions ranging from tens of kilobases to megabases with the same basic protocol. We anticipate this technology will lead to an enhanced ability to visualize interphase and metaphase chromosomes. PMID:23236188

Beliveau, Brian J; Joyce, Eric F; Apostolopoulos, Nicholas; Yilmaz, Feyza; Fonseka, Chamith Y; McCole, Ruth B; Chang, Yiming; Li, Jin Billy; Senaratne, Tharanga Niroshini; Williams, Benjamin R; Rouillard, Jean-Marie; Wu, Chao-ting

2012-12-26

230

The cyclic cystine ladder of theta-defensins as a stable, bifunctional scaffold: A proof-of-concept study using the integrin-binding RGD motif.  

Science.gov (United States)

Peptides have the specificity and size required to target the protein-protein interactions involved in many diseases. Some cyclic peptides have been utilised as scaffolds for peptide drugs because of their stability; however, other cyclic peptide scaffolds remain to be explored. ?-Defensins are cyclic peptides from mammals; they are characterised by a cyclic cystine ladder motif and have low haemolytic and cytotoxic activity. Here we demonstrate the potential of the cyclic cystine ladder as a scaffold for peptide drug design by introducing the integrin-binding Arg-Gly-Asp (RGD) motif into the ?-defensin RTD-1. The most active analogue had an IC50 of 18 nM for the ?v ?3 integrin as well as high serum stability, thus demonstrating that a desired bioactivity can be imparted to the cyclic cystine ladder. This study highlights how ?-defensins can provide a stable and conformationally restrained scaffold for bioactive epitopes in a ?-strand or turn conformation. Furthermore, the symmetry of the cyclic cystine ladder presents the opportunity to design peptides with dual bioactive epitopes to increase activity and specificity. PMID:24382674

Conibear, Anne C; Bochen, Alexander; Rosengren, K Johan; Stupar, Petar; Wang, Conan; Kessler, Horst; Craik, David J

2014-02-10

231

9 CFR 93.911 - Ports designated for the importation of live VHS-regulated fish species.  

Science.gov (United States)

IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN ANIMAL, BIRD, AND POULTRY PRODUCTS; REQUIREMENTS FOR MEANS OF CONVEYANCE AND SHIPPING CONTAINERS Aquatic Animal Species General Provisions for Vhs-Regulated Fish Species §...

2010-01-01

232

Electronic transport through a ladder nano structure in the presence of network defects  

International Nuclear Information System (INIS)

The present research studied the electronic transport of an ideal infinite ladder nano structure in the presence/absence of network defects by using Green's function method at the tight-binding approximation. The network defects can be simulated by considering a finite ladder which is connected via two contacts to two similar infinite ladders. The results showed that the hopping energy of rungs determines the overlapping region of the ladder conductance channels. By increasing hopping energy of rungs, the allowed energy region of the ladder increases, while the overlapping region shrinks and eventually vanishes. Creation of branched bonds in the center ladder leads, through the system, to a harder electron tunneling. Moreover, the closer electron energy to the system gap edges leads to a better tunneling.

233

Density Matrix Recursion Method: Genuine Multisite Entanglement Distinguishes Odd from Even Quantum Heisenberg Ladders  

CERN Document Server

We introduce an analytical iterative method, the density matrix recursion method, to generate arbitrary reduced density matrices, and bipartite as well as multipartite entanglement of multi-legged periodic spin-1/2 quantum Heisenberg ladders with an arbitrary number of legs. We apply this technique to distinguish between even- and odd-legged ladders. Specifically, we show that while multipartite entanglement decreases with increasing system-size for even-legged ladders, it does the opposite for odd-legged ones.

Dhar, Himadri Shekhar; Sen, Ujjwal

2011-01-01

234

Fish schooling as a basis for vertical axis wind turbine farm design.  

Science.gov (United States)

Most wind farms consist of horizontal axis wind turbines (HAWTs) due to the high power coefficient (mechanical power output divided by the power of the free-stream air through the turbine cross-sectional area) of an isolated turbine. However when in close proximity to neighboring turbines, HAWTs suffer from a reduced power coefficient. In contrast, previous research on vertical axis wind turbines (VAWTs) suggests that closely spaced VAWTs may experience only small decreases (or even increases) in an individual turbine's power coefficient when placed in close proximity to neighbors, thus yielding much higher power outputs for a given area of land. A potential flow model of inter-VAWT interactions is developed to investigate the effect of changes in VAWT spatial arrangement on the array performance coefficient, which compares the expected average power coefficient of turbines in an array to a spatially isolated turbine. A geometric arrangement based on the configuration of shed vortices in the wake of schooling fish is shown to significantly increase the array performance coefficient based upon an array of 16 x 16 wind turbines. The results suggest increases in power output of over one order of magnitude for a given area of land as compared to HAWTs. PMID:20729568

Whittlesey, Robert W; Liska, Sebastian; Dabiri, John O

2010-09-01

235

Fish schooling as a basis for vertical axis wind turbine farm design  

Energy Technology Data Exchange (ETDEWEB)

Most wind farms consist of horizontal axis wind turbines (HAWTs) due to the high power coefficient (mechanical power output divided by the power of the free-stream air through the turbine cross-sectional area) of an isolated turbine. However when in close proximity to neighboring turbines, HAWTs suffer from a reduced power coefficient. In contrast, previous research on vertical axis wind turbines (VAWTs) suggests that closely spaced VAWTs may experience only small decreases (or even increases) in an individual turbine's power coefficient when placed in close proximity to neighbors, thus yielding much higher power outputs for a given area of land. A potential flow model of inter-VAWT interactions is developed to investigate the effect of changes in VAWT spatial arrangement on the array performance coefficient, which compares the expected average power coefficient of turbines in an array to a spatially isolated turbine. A geometric arrangement based on the configuration of shed vortices in the wake of schooling fish is shown to significantly increase the array performance coefficient based upon an array of 16 x 16 wind turbines. The results suggest increases in power output of over one order of magnitude for a given area of land as compared to HAWTs.

Whittlesey, Robert W; Liska, Sebastian; Dabiri, John O, E-mail: robertw@caltech.ed, E-mail: jodabiri@caltech.ed [Graduate Aeronautical Laboratories, California Institute of Technology, 1200 E California Blvd, MC 205-45, Pasadena, CA 91125 (United States)

2010-09-15

236

Spatially resolved fish population analysis for designing MPAs : influence on inside and neighbouring habitats  

DEFF Research Database (Denmark)

The sandeel population analysis model (SPAM) is presented as a simulation tool for exploring the efficiency of Marine Protected Areas (MPAs) for sandeel stocks. SPAM simulates spatially resolved sandeel population distributions, based on a high-resolution map of all fishery-established sandbank habitats for settled sandeels, combined with a life-cycle model for survival, growth, and reproduction, and a three-dimensional hydrodynamic model for describing larval transport between the network of habitats. SPAM couples stock dynamics to ecosystem and anthropogenic forcing via well-defined drivers. The SPAM framework was tested using ICES statistical rectangle 37F2 as an MPA, and the impact on sandeel populations within the MPA and neighbouring habitats was investigated. Increased larval spillover compensated for lost catches inside the MPA. The temporal and spatial scales of stock response to MPAs demonstrated that ecosystem self-regulation must be included when modelling the efficiency of MPAs, and for lesser sandeel, that self-regulation partially counteracts the benefits of a fishing sanctuary. The use of realistic habitat connectivity is critical for both qualitative and quantitative MPA assessment. The results confirm that the stock levels are more sensitive to changes in life conditions of larval stages than later parts of the life cycle.

Christensen, AsbjØrn; Mosegaard, Henrik

2009-01-01

237

Science Career Ladder at the NY Hall of Science: Youth Facilitators as Agents of Inquiry  

Science.gov (United States)

The New York Hall of Science is New York City's hands-on science and technology center, with more than 400 interactive exhibits exploring physics, chemistry, and biology. The Hall also creates and presents demonstrations and programs for students and families, and is the leading provider of professional development in the physical sciences for New York City teachers. The Hall is located in Queens, the most ethnically diverse county in the country. Therefore, a centerpiece of the Hall's efforts to build and support diversity is its Science Career Ladder (SCL): a program that engages young people in a hierarchy of paid experiences in the museum, designed to cultivate interest in science and science education as possible career paths.

Siegel, Eric; Gupta, Preeti

2008-01-01

238

Resistivity of Doped Two-Leg Spin Ladders  

CERN Document Server

In doped two-leg spin ladder systems, holes are expected to form charged bosonic pairs. We study charge transport in this system in the temperature range where the bosons can be described as weakly interacting quasi-particles. We consider boson-phonon and boson-impurity scattering processes. We suggest that due to the Ioffe-Regel resistivity saturation mechanism, the resistivity may exhibit a local maximum at intermediate temperatures. We propose that this may explain a similar feature found in recent experimental results.

Carneiro, G M; Carneiro, Gilson; Lederer, Pascal

1997-01-01

239

Beyond rainbow-ladder in bound state equations  

International Nuclear Information System (INIS)

In this work we devise a new method to study quark-anti-quark interactions beyond simple ladder-exchange that yield massless pions in the chiral limit. The method is based on the requirement to have a representation of the quark-gluon vertex that is explicitly given in terms of quark dressings functions. We outline a general procedure to generate the Bethe-Salpeter kernel for a given vertex representation. Our method allows not only the identification of the mesons' masses but also the extraction of their Bethe-Salpeter wave functions exposing their internal structure. We exemplify our method with vertex models that are of phenomenological interest. (orig.)

240

Exact solutions and ladder operators for a new anharmonic oscillator  

International Nuclear Information System (INIS)

In this Letter, we propose a new anharmonic oscillator and present the exact solutions of the Schrodinger equation with this oscillator. The ladder operators are established directly from the normalized radial wave functions and used to evaluate the closed expressions of matrix elements for some related functions. Some comments are made on the general calculation formula and recurrence relation for off-diagonal matrix elements. Finally, we show that this anharmonic oscillator possesses a hidden symmetry between E(r) and E(ir) by substituting r->ir

 
 
 
 
241

Quantum spin ladder systems associated with SU(2|2)  

International Nuclear Information System (INIS)

Two integrable quantum spin ladder systems will be introduced associated with the fundamental SU 92/20 solution of the Yang-baxter equation. The first model is a generalized quantum Ising system with Ising rung interactions. In the second model the addition of extra interactions allows us to impose Heisenberg rung interactions without violating integrability. The existence of a Bethe ansatz solution for both models allows us to investigate the elementary excitations for antiferromagnetic rung couplings. We find that the first model does not show a gap whilst in the second case there is a gap for all positive values of the rung coupling. (author)

242

Quantum Phase Transitions and Dimerized Phases in Frustrated Spin Ladder  

International Nuclear Information System (INIS)

In this paper, we study the phase diagram of a frustrated spin ladder model by applying the bosonization technique and the density-matrix renormalization-group (DMRG) algorithm. Effect of the intra-chain next-nearestneighbor (NNN) super-exchange interaction is investigated in detail and the order parameters are calculated to detect the emergence of the dimerized phases. We find that the intra-chain NNN interaction plays a key role in inducing dimerized phases. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

243

Period halving of Persistent Currents in Mesoscopic Mobius ladders  

CERN Document Server

We investigate the period halving of persistent currents(PCs) of non-interacting electrons in isolated mesoscopic M\\"{o}bius ladders without disorder, pierced by Aharonov-Bhom flux. The mechanisms of the period halving effect depend on the parity of the number of electrons as well as on the interchain hopping. Although the data of PCs in mesoscopic systems are sample-specific, some simple rules are found in the canonical ensemble average, such as all the odd harmonics of the PCs disappear, and the signals of even harmonics are non-negative. {PACS number(s): 73.23.Ra, 73.23.-b, 68.65.-k}

Wen Ji Deng; Ping, L I U; Wen-Ji, DENG; Ji-Huan, XU; Ping, LIU

2002-01-01

244

The phonon and thermal properties of a ladder nanostructure  

Directory of Open Access Journals (Sweden)

Full Text Available  In this paper, we study the phonon thermal properties of a ladder nanostructure in harmonic approximation. We present a model consisting of two infinite chains with different masses. Then, we investigate the effect of different masses on the phonon spectrum. Moreover, as a specific case, in the absence of the second neighbor interaction, we calculate the phonon density of states/modes. Finally, we consider the thermal conductivity of the system. The results show that the phonon spectrum shifts down to the lower frequencies by increasing the masses. Furthermore, a frequency gap appears in the phonon spectrum. By increasing the springs constants, the thermal conductance decreases.

M Mardaani

2011-12-01

245

Beyond rainbow-ladder in bound state equations  

Energy Technology Data Exchange (ETDEWEB)

In this work we devise a new method to study quark-anti-quark interactions beyond simple ladder-exchange that yield massless pions in the chiral limit. The method is based on the requirement to have a representation of the quark-gluon vertex that is explicitly given in terms of quark dressings functions. We outline a general procedure to generate the Bethe-Salpeter kernel for a given vertex representation. Our method allows not only the identification of the mesons' masses but also the extraction of their Bethe-Salpeter wave functions exposing their internal structure. We exemplify our method with vertex models that are of phenomenological interest. (orig.)

Heupel, Walter; Goecke, Tobias; Fischer, Christian S. [Justus-Liebig-University Giessen, Institute for Theoretical Physics, Giessen (Germany)

2014-05-15

246

Absence of extended states in a ladder model of DNA  

CERN Document Server

We consider a ladder model of DNA for describing carrier transport in a fully coherent regime through finite segments. A single orbital is associated to each base, and both interstrand and intrastrand overlaps are considered within the nearest-neighbor approximation. Conduction through the sugar-phosphate backbone is neglected. We study analytically and numerically the spatial extend of the corresponding states by means of the Landauer and Lyapunov exponents. We conclude that intrinsic-DNA correlations, arising from the natural base pairing, does not suffice to observe extended states, in contrast to previous claims.

Díaz, E; Sedrakyan, D; Domínguez-Adame, F

2006-01-01

247

Optical coherences and wavelength mismatch in ladder systems  

CERN Document Server

We investigate experimentally and theoretically the coherent and incoherent processes in open 3-level ladder systems in room temperature gases and identify in which regime electromagnetically induced transparency (EIT) occurs. The peculiarity of this work lies in the unusual situation where the wavelength of the probe field is shorter than that of the coupling field. The nature of the observed spectral features depends considerably on the total response of different velocity classes, the varying Doppler shifts for bichromatic excitation fields, on optical pumping to additional electronic states and transit time effects. All these ingredients can be absorbed in a model based on optical Bloch equations with only five electronic states.

Urvoy, A; Ritter, R; Adams, C S; Weatherill, K J; Löw, R

2013-01-01

248

Optical coherences and wavelength mismatch in ladder systems  

Science.gov (United States)

We investigate experimentally and theoretically the coherent and incoherent processes in open three-level ladder systems in room temperature gases and identify in which regime electromagnetically induced transparency (EIT) occurs. The peculiarity of this work lies in the unusual situation where the wavelength of the probe field is shorter than that of the coupling field. The nature of the observed spectral features depends considerably on the total response of different velocity classes, the varying Doppler shifts for bichromatic excitation fields, on optical pumping to additional electronic states and transit time effects. All these ingredients can be absorbed in a model based on optical Bloch equations with only five electronic states.

Urvoy, A.; Carr, C.; Ritter, R.; Adams, C. S.; Weatherill, K. J.; Löw, R.

2013-12-01

249

Beyond Rainbow-Ladder in bound state equations  

CERN Document Server

In this work we devise a new method to study quark anti-quark interactions beyond simple ladder-exchange that yield massless pions in the chiral limit. The method is based on the requirement to have a representation of the quark-gluon vertex that is explicitly given in terms of quark dressings functions. We outline a general procedure to generate the Bethe-Salpeter kernel for a given vertex representation. Our method allows not only the identification of the mesons' masses but also the extraction of their Bethe-Salpeter wave functions exposing their internal structure. We exemplify our method with vertex models that are of phenomenological interest.

Heupel, Walter; Fischer, Christian S

2014-01-01

250

One Fish Two Fish.  

Science.gov (United States)

This activity explains fisheries resource management to seven-year olds. First-grade students learn concepts such as offspring viability, life expectancy, and distribution of species, which help to determine when, where, and how people fish and the importance of fishing responsibly. Lists materials, procedures, and extensions. (SJR)

Hoffman, Michele

1998-01-01

251

Orientation through chemo reception in fishes  

Science.gov (United States)

A system designed to acquire and process data describing locomotor behavior of fish is described. Data are recorded in relation to the fish's response to olfactory stimuli. It was concluded that fish orientation is based on rheataxis or chemotropotaxis.

Kleerekoper, H.

1972-01-01

252

Dissipation, Voltage Profile and Levy Dragon in a Special Ladder Network  

Science.gov (United States)

A ladder network constructed by an elementary two-terminal network consisting of a parallel resistor-inductor block in series with a parallel resistor-capacitor block sometimes is said to have a non-dispersive dissipative response. This special ladder network is created iteratively by replacing the elementary two-terminal network in place of the…

Ucak, C.

2009-01-01

253

Characterising reef fish populations and habitats within and outside the US Virgin Islands Coral Reef National Monument: A lesson in marine protected area design  

Science.gov (United States)

Marine protected areas are an important tool for management of marine ecosystems. Despite their utility, ecological design criteria are often not considered or feasible to implement when establishing protected areas. In 2001, the Virgin Islands Coral Reef National Monument (VICRNM) in St John, US Virgin Islands was established by Executive Order. The VICRNM prohibits almost all extractive uses. Surveys of habitat and fishes inside and outside of the VICRNM were conducted in 2002-2004. Areas outside the VICRNM had significantly more hard corals, greater habitat complexity, and greater richness, abundance and biomass of reef fishes than areas within the VICRNM. The administrative process used to delineate the boundaries of the VICRNM did not include a robust ecological characterisation of the area. Because of reduced habitat complexity within the VICRNM, the enhancement of the marine ecosystem may not be fully realised or increases in economically important reef fishes may take longer to detect. ?? 2007 The Authors. Journal compilation ?? 2007 Blackwell Publishing Ltd.

Monaco, M. E.; Friedlander, A. M.; Caldow, C.; Christensen, J. D.; Rogers, C.; Beets, J.; Miller, J.; Boulon, R.

2007-01-01

254

DNA sequencing and genotyping by transcriptional synthesis of chain-terminated RNA ladders and MALDI-TOF mass spectrometry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Sets of RNA ladders can be synthesized by transcription of a bacteriophage-encoded RNA polymerase using 3?-deoxynucleotides as chain terminators. These ladders can be used for sequencing of DNA. Using a nicked form of phage SP6 RNA polymerase in this study substantially enhanced yields of transcriptional sequencing ladders. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of chain-terminated RNA ladders allowed DN...

Kwon, Young-soo; Tang, Kai; Cantor, Charles R.; Ko?ster, Hubert; Kang, Changwon

2001-01-01

255

The effect of instructions on potential slide-out failures during portable extension ladder angular positioning.  

Science.gov (United States)

Accidents involving portable ladders are a common cause of serious occupational and non-occupational injuries throughout the industrialized world. Many of these injuries could be prevented with better instruction on the proper usage of portable ladders. Research is reported that focused on both the human factors and engineering aspects of portable extension ladder usage based on common ladder setup procedures. Results of the human factors experiment revealed evidence of unsafe acts that could lead to catastrophic ladder slide-out accidents in real-life situations. Six different ladder setup methods were evaluated for safety and stability based on placement angles: the basic, 75 degree, stand-reach, L sticker, 4:1, and bubble level methods. Ideally, ladder users would set the ladder up at 75.5 degrees to achieve the consensus industry standard safest angle. Setup methods varied in complexity and nature of instruction. The level method produced the most accurate and the least variable results. The engineering analysis determined the coefficient of friction of a variety of clean and contaminated surfaces commonly used with ladders. This analysis determined the total number of slide-out failures that would likely have occurred in the data obtained in each of the ladder setup methods tested in the human factors experiment. Based on test participants' setup angles, the average calculated ladder slide-out failure rate was 8.7 percent for ladders positioned on a surface with the lowest measured coefficient of friction. When broken down by ladder setup method, the 4:1 method had a failure rate of 18.8 percent, the 75 degree method had a failure rate of 15.2 percent, and the basic method had a failure rate of 9.8 percent. The stand-reach and L sticker methods had identical failure rates at 3.3 percent and the level method was best at 1.1 percent. The level method provided the lowest error, least variability, and setup closest to the target angle of 75.5 degrees. Analysis of the overall results revealed the need for additional user training and clearer instructions affixed to ladders. This research is unique in that it combines an analysis and comparison of human factors and engineering in the same study. PMID:24594362

Campbell, Alan O; Pagano, Christopher C

2014-06-01

256

Antiferromagnetic spin ladders effectively coupled by one-dimensional electron liquids  

CERN Document Server

We study a model of the stripe state in strongly correlated systems consisting of a array of antiferromagnetic spin ladders, each with $n_{\\rm{leg}}$ legs, coupled to each other through the spin-exchange interaction to charged stripes in between each pair of ladders. The charged stripe are assumed to be Luttinger liquids in a spin-gap regime (Luther-Emery). An effective interaction for a pair of neighboring ladders is calculated by integrating out the gapped spin degree of freedom in the charged stripe. The low energy effective theory of each ladder is the usual nonlinear $\\sigma$-model with additional cross couplings of neighboring ladders. These interactions are found to favor either in-phase or anti-phase short range spin orderings depending on whether the charge stripe is site-centered or bond-centered as well as on its filling factor and other physical parameters of the charged stripe.

Liu, W V; Fradkin, Eduardo

2001-01-01

257

The Doped t-J Ladder via series expansions  

International Nuclear Information System (INIS)

Full text: We have developed a new series expansion approach for calculating the zero-temperature properties of lattice electron models for arbitrary finite doping. This is done by introducing particle fluctuation terms in the Hamiltonian, within perturbation theory. The method is demonstrated by application to the 2-chain t-J ladder. This model has been extensively studied, in connection with materials such as SrCu2O3. There is evidence that some of these systems become superconducting upon doping. Results will be presented for the ground state energy, chemical potential, and spin excitations. Comparisons with previous work will be given. We have also recently developed a series expansion method for calculating precisely the spectra of two-particle bound states, and here we apply this new technique to study the dynamic properties of 2-holes doped into the t-J ladder. The overall 2-hole spectrum is much richer than that obtained in previous studies. Several singlet and triplet bound/antibound states are found. The number of bound states depends on the coupling constants as well as the wavevector

258

Two experimental fish aggregating systems (fads) in the Aegean sea: their design and application  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Duas bóias de aço spar foram construídas e ancoradas em 50 e 100 m de profundidade nas águas do Mar Egeu para dar apoio à pesca recreativa. O primeiro FAD foi implantado nas coordenadas 38°01'48''N 26°58'02''E, a uma distância de 3 milhas náuticas da costa. O outro ficou ancorado a 1,1 milha náutica [...] da costa nas coordenadas 38°03'11''N; 26°59'01''E. Uma âncora (1.2x1.2x0.8 m3), pesando aproximadamente 2,76 toneladas, feita de concreto armado, foi usada para prender um FAD de peso aproximado de 1,5 toneladas. Foram realizados cálculos para determinação das conexões dos FADs, dos cabos e da ancoragem. A interação entre as forças de ondas e correntes com os FADs foi também investigada. No experimento, todas as forças (força de arrasto, força de empuxo, etc) atuantes sobre os FADs foram calculadas. É proposto que para a construção dos FADs deverão ser levados em consideração os seguintes fatores: ondas e correntes, forças relacionadas com os FADs, profundidade de implantação, sistema computacional dos moorings e cordas de amarração. Esse conhecimento proporcionará referência importante para os interessados em realizar projetos que visem aumentar o desempenho e a vida útil dos FADs. Abstract in english Two steel spar buoys were constructed and moored in 50 and 100 m deep of water in the Aegean Sea to support recreational fisheries. The first FAD was deployed at coordinates 38°01´48´´N 26°58´02´´E and at a distance of 3 nautical miles from the shoreline. The other FAD was moored at 1.1 nautical mil [...] es from the shoreline at coordinates 38°03´11´´N; 26°59´01´´E. An anchor (1.2x1.2x0.8 m3) weighing approximate 2.76 metric ton, made of reinforced concrete, was used to hold a FAD weighing approximate 1.5 metric ton. Hardware and connections of FADs, ropes, mooring calculation and anchor design were made. The interaction between the forces of wave and current and FADs in those waters was investigated. In the experiment, all forces (drag force, buoyancy force etc.) acting on FADs were calculated. It is proposed that the construction of the FADs should take the following design criteria into consideration: wave and current, forces related to the FADs, deployment depth, mooring hardware and ropes. This knowledge provides an important reference for stakeholders performing projects aiming to increase the performance and service life FADs.

Aytaç, Özgül; Altan, Lök; F. Ozan, Düzbastilar.

259

Heisenberg S=1/2 Spin Ladders: New Molecular-Based Examples  

Science.gov (United States)

Heisenberg spin ladders have a cooperative spin singlet ground state and two critical fields. The ratios of the two fields depend on the ratio of the interaction strengths along the rungs and along the rails of the ladder. Coordination polymers provide examples of spin ladders with exchange strengths small enough to induce critical fields that are less than 60 tesla. To date these molecular-based compounds consist either of lattices of CuBr4 dianions packed into ladders by large organic molecules [1,2] or neutral Cu2X4 dimers (X = Cl, Br) linked into ladders by bridging diazine molecules such as quinoxaline [3]. We present the structures and results of magnetic measurements of three new spin ladders, (quinolinium)2CuBr4, Cu(methylpyrazine)Cl2, and Cu(2,3-dimethylpyrazine)Cl2. The susceptibility of each of the compounds possesses a characteristic rounded maximum near 20 K, with a rapid decrease at lower temperatures. Comparison of the data for Cu(2,3-dimethylpyrazine)Cl2 to a spin ladder model reveals the rung and rail exchange constants to be 29.0 K and 17.2 K, respectively. [1] C. P. Landee et al, Phys. Rev. B 63, R100402 (2001). [2] R D. Willett et al, Inorganic Chemistry 43, 3804-3811 2004). [3] C. P. Landee et al, Polyhedron 22, 2325-2329 (2003).

Landee, Christopher; Shapira, A.

2005-03-01

260

Vitamin content of fish and fish products consumed in Portugal  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Portuguese Food Composition Table only includes values for vitamins A, B1, B2, PP determined before 1963. Most fish and fish products consumed in Portugal are not included in international food composition tables. Aims: To study vitamin content of fish and fish products consumed in Portugal. Design: Vitamins A, E, D, B1, B2, B6, B12, PP and Folate content was determined in fifty-six samples of raw and cooked fish and fish products, collected between October 1999 and February 2002....

Dias, M. Grac?a; Sa?nchez, M. V.; Ba?rtolo, H.; Oliveira, Lui?sa

2003-01-01

 
 
 
 
261

Consumers' perceptions of African wildlife meat : A laddering study  

DEFF Research Database (Denmark)

African wildlife meat offers South Africans' a healthy and novel red meat alternative, yet consumption is far less than that of beef and lamb. Laddering interviews with 40 respondents were employed to identify the consequences and values associated with the product's perceived attributes. Important attributes included low levels of fat, dryness, novelty, and special preparation requirements. Significant values included security, self-esteem, hedonism, tradition, and stimulation. Promoters of the product are advised to capitalize on consumers' interest in health and the health benefits of the meat in their advertising strategy. They can also address current barriers to consumption as indicated by negative, undesirable consequences (difficult and time-consuming to prepare) by promoting quick and easy ways of preparation, provision of ready-to-eat dishes and training.

Radder, Laetitia; Grunert, Klaus G.

2009-01-01

262

Breathers in Josephson junction ladders: Resonances and electromagnetic wave spectroscopy  

DEFF Research Database (Denmark)

We present a theoretical study of the resonant interaction between dynamical localized states (discrete breathers) and linear electromagnetic excitations (EE's) in Josephson junction ladders. By making use of direct numerical simulations we find that such an interaction manifests itself by resonant steps and various sharp switchings (voltage jumps) in the current-voltage characteristics. Moreover, the power of ac oscillations away from the breather center (the breather tail) displays singularities as the externally applied dc bias decreases. All these features may be mapped to the spectrum of EE's that has been derived analytically and numerically. Using an improved analysis of the breather tail, a spectroscopy of the EE's is developed, The nature of breather instability driven by localized EE's is established.

Miroshnichenko, A. E.; Flach, S.

2001-01-01

263

Attractive Tomonaga-Luttinger Liquid in a Quantum Spin Ladder  

Science.gov (United States)

We present NMR measurements of a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15 T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR lines, we determine the phase boundary and the order parameter of the low-temperature (three-dimensional) long-range-ordered phase. In the Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects characteristic power-law decay of spin correlation functions as 1/T1?T1/2K-1, which allows us to determine the interaction parameter K as a function of field. We find that field-dependent K varies within the 1

Jeong, M.; Mayaffre, H.; Berthier, C.; Schmidiger, D.; Zheludev, A.; Horvati?, M.

2013-09-01

264

Generalized Kaluza-Klein monopole, quadratic algebras and ladder operators  

Energy Technology Data Exchange (ETDEWEB)

We present a generalized Kaluza-Klein monopole system. We solve this quantum superintegrable system on a Euclidean Taub Nut manifold using the separation of variables of the corresponding Schroedinger equation in spherical and parabolic coordinates. We present the integrals of motion of this system, the quadratic algebra generated by these integrals, the realization in terms of a deformed oscillator algebra using the Daskaloyannis construction and the energy spectrum. The structure constants and the Casimir operator are functions not only of the Hamiltonian but also of other two integrals commuting with all generators of the quadratic algebra and forming an Abelian subalgebra. We present another algebraic derivation of the energy spectrum of this system using the factorization method and ladder operators.

Marquette, Ian, E-mail: im553@york.ac.uk [Department of Mathematics, University of York, Heslington, York YO10 5DD (United Kingdom)

2011-06-10

265

Formalism for fuzzy automation Petri Nets to Ladder Logic Diagrams  

Directory of Open Access Journals (Sweden)

Full Text Available Process automation has been the default standard for industries since processors are prominently figured in the scheme of production. The significant characteristic of Process automation is clarity in the definition of tasks, sequence of operation and concurrency. Programmable Logic Controllers are a set of this morphing of processors prominently favored in the Process Automation due to its ease of use, ruggedness and low cost. PLC, as it is abbreviated is preferred also because of most important reason - ease of programming. Programming of PLC was started with Ladder Logic Diagrams and in spite of other developed high level languages plays a prominent role even today. This problem however is recognized and programming for DES is suggested via a modified approach called Grafcet. In this paper, a fuzzy formalism is introduced into the modeling system as Fuzzy Automation Petri Nets (FAPN and formal method for conversion of this FAPN into LLD is suggested.

S. Meenatchisundaram

2009-12-01

266

Transport coefficients and ladder summation in hot gauge theories  

CERN Document Server

We show how to compute transport coefficients in gauge theories by considering the expansion of the Kubo formulas in terms of ladder diagrams in the imaginary time formalism. All summations over Matsubara frequencies are performed and the analytical continuation to get the retarded correlators is done. As an illustration of the procedure, we present a derivation of the transport equation for the shear viscosity in the scalar theory. Assuming the Hard Thermal Loop approximation for the screening of distant collisions of the hard particles in the plasma, we derive a couple of integral equations for the effective vertices which, to logarithmic accuracy, are shown to be identical to the linearized Boltzmann equations previously found by Arnold, Moore and Yaffe.

Valle-Basagoiti, M A

2002-01-01

267

Phase sensitive quantum interference on forbidden transition in ladder scheme  

CERN Document Server

A three level ladder system is analyzed and the coherence of initially electric-dipole forbidden transition is calculated. Due to the presence of two laser fields the initially dipole forbidden transition becomes dynamically permitted due to ac Stark effect. It is shown that such transitions exhibit quantum-interference-related phenomena, such as electromagnetically induced transparency, gain without inversion and enhanced refractive index. Gain and dispersion characteristics of such transitions strongly depend upon the relative phase between the driving and the probe fields. Unlike allowed transitions, gain/absorption behavior of ac-Stark allowed transitions exhibit antisymmetric feature on the Rabi sidebands. It is found that absorption/gain spectra possess extremely narrow sub-natural resonances on these ac Stark allowed forbidden transitions. An interesting finding is simultaneous existence of gain and negative dispersion at Autler-Townes transition which may lead to both reduction of the group velocity a...

Koganov, Gennady A

2014-01-01

268

Magnetism in the pseudo-two-leg ladder compound CaCu2O3  

International Nuclear Information System (INIS)

Contrary to SrCu2O3, the pseudo-ladder two-leg compound CaCu2O3 does not show a significant spin-gap behavior as expected for typical two-leg ladder systems. Magnetization measurements on single crystals show CaCu2O3 to be a three-dimensional (3D) antiferromagnet (T N=27 K), showing relatively strong magnetic anisotropy and metamagnetic transitions. The 3D behavior is due to exchange between the ladders as deduced from electronic structure calculations within the local density approximation

269

The density matrix recursion method: genuine multisite entanglement distinguishes odd from even quantum spin ladder states  

International Nuclear Information System (INIS)

We introduce an analytical iterative method, the density matrix recursion method, to generate arbitrary reduced density matrices of superpositions of short-range dimer coverings on periodic or non-periodic quantum spin-1/2 ladder lattices, with an arbitrary number of legs. The method can be used to calculate bipartite as well as multipartite physical properties, including bipartite and multi-partite entanglement. We apply this technique to distinguish between even- and odd-legged ladders. Specifically, we show that while genuine multi-partite entanglement decreases with increasing system size for the even-legged ladder states, it does the opposite for odd-legged ones. (paper)

270

Hamiltonians with two-ladder spectra and solutions to the Painlevé IV equation  

Science.gov (United States)

Some supersymmetric partners of the harmonic oscillator Hamiltonian possess third-order differential ladder operators and, thus, they realize the second-order polynomial Heisenberg algebras. The corresponding spectra consist of an infinite ladder of energy levels plus a finite one that can be placed at any position with respect to the infinite ladder. Both of them have equally spaced energy levels. Departing from these Hamiltonians several families of real and complex solutions to the Painlevé IV equation with real parameters will be generated.

Bermudez, David; Fernández C, David J.

2014-05-01

271

Thermodynamics of the Spin Luttinger Liquid in a Model Ladder Material  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The phase diagram in temperature and magnetic field of the metal-organic, two-leg, spin-ladder compound (C5H12N)(2)CuBr4 is studied by measurements of the specific heat and the magnetocaloric effect. We demonstrate the presence of an extended spin Luttinger-liquid phase between two field-induced quantum critical points and over a broad range of temperature. Based on an ideal spin-ladder Hamiltonian, comprehensive numerical modeling of the ladder specific heat yields excellent quantitative agr...

2008-01-01

272

An Evaluation of the Selectivity Characteristics of Different Juvenile Fish Escape Panel Designs for the Demersal Trap Fishery of Abu Dhabi, United Arab Emirates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The selectivity characteristics of 4 juvenile fish escape panel designs and their utility for the regulation of a multi-species demersal trap fishery were evaluated using a suite of objective socio-economic and biological criteria. The panel designs consisted of a control (type A) which had a hexagonal mesh size which was the same as that of the body of the trap (3.5 cm), a rectangular mesh (type B) which was representative of the current regulation (5.0 x 7.6 cm) and 2 escape panels with squ...

Edwin Mark Grandcourt; Thabit Zahran Al Abdessalaam; Stanley Alexander Hartmann; Ahmed Tarish Al Shamsi; Franklin Francis

2011-01-01

273

Ab initio study of ladder-type polymers polythiophene and polypyrrole  

CERN Document Server

This article presents an \\textit{ab initio} study of four polymers, polythiophene, polypyrrole, ladder-type polythiophene, and ladder-type polypyrrole. Upon an analysis of the variation of the band gap when comparing the unconstrained and the ladder-type polymers, a discrepancy was found between the thiophene and the pyrrole polymer families. For polythiophene, the ladder-type polymer has a larger gap than the unconstrained polymer whereas the opposite is found for the pyrrole polymers. The structural properties and the charge densities using the Bader charge analysis of these four compounds are investigated. The different band gap behaviors in thiophene and pyrrole polymers can be explained in terms of the competition between the bond length alternation and the effect of the charge density in the carbon backbone.

Pesant, S; Côté, M; Ernzerhof, M; Pesant, Simon; Boulanger, Paul; C\\^ot\\'e, Michel; Ernzerhof, Matthias

2006-01-01

274

Staggered orbital currents in the half-filled two-leg ladder  

CERN Document Server

Using abelian bosonization we show that a certain phase of the half-filled two-leg ladder, previously identified as having spin-Peierls order, instead exhibits staggered orbital currents with no dimerization.

Fjaerestad, J O

2002-01-01

275

Computational flow simulation supporting the design of the Geesthacht fish pass; Numerische Modelluntersuchungen im Rahmen der Planung der Fischaufstiegsanlage Geesthacht  

Energy Technology Data Exchange (ETDEWEB)

In the year 2010 Europe's largest fish pass with basins at the Elbe-weir near Geesthacht was put into operation. Since then fish of many different kinds and sizes pass the building every day. The geometrical configuration of the facility, realized as a double slot pass, is based on extensive hydraulic model investigations. Thereby, apart from the flow characteristic within the building, also location-specific and operational aspects were to be analyzed and integrated into the planning concept. Due to the complex hydraulic boundary conditions as well as the high fish-ecological requirements a hybrid modeling approach with computational flow simulation in connection with physical model tests was employed, whereby substantial synergies as well as a good prognosis ability of the computer-aided simulation showed up. (orig.)

Oberle, Peter; Musall, Mark; Riesterer, Jochen; Nestmann, Franz [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (DE). Inst. fuer Wasser und Gewaesserentwicklung (IWG)

2012-07-01

276

Dare we jump off Arnstein's ladder? Social learning as a new policy paradigm  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Participation is now a central consideration of policy discourses at EU; national and local levels, particularly in relation to environmental resources. As it becomes a social expectation so the form, meaning and purpose of participation has diversified. While Arnstein’s ladder of citizen participation (Arnstein, 1969) revealed that much ‘participation’ does little to broker a reassignment of power, this paper argues that it is perhaps time to jump off the ladder. In doing so, we sugges...

Collins, Kevin; Ison, Raymond

2006-01-01

277

Means – End Chain Theory and Laddering Technique: Applications in Consumer Behavior Research  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Means – end chain (MEC) theory and laddering technique uncovers the decision making process of consumers related to marketing offerings such as goods, services and experiences in a cognitive approach from a consumer perspective view which are popularly used approaches in marketing context. The purpose of the study is to discusss and present the laddering techique to Turkish literature, which is a frequently used qualitative research method in consumer behavior, both with related theoretical...

Ayca Kangal

2013-01-01

278

Training Algorithm for Extra Reduced Size Lattice-Ladder Multilayer Perceptrons  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A quick gradient training algorithm for a specific neural network structure called an extra reduced size lattice-ladder multilayer perceptron is introduced. Presented derivation of the algorithm utilizes recently found by author simplest way of exact computation of gradients for rotation parameters of lattice-ladder filter. Developed neural network training algorithm is optimal in terms of minimal number of constants, multiplication and addition operations, while the regularity of the structu...

Navakauskas, Dalius

2003-01-01

279

Persistent currents in a Möbius ladder A test of interchain coherence of interacting electrons  

CERN Document Server

Persistent currents in a Moebius ladder are shown to be very sensitive to the effects of intrachain interactions on the hopping of electrons between chains. Their periodicity as a function of flux is doubled for strong enough repulsive interactions because electrons cannot hop coherently between the chains and have to travel along the full edge of the Moebius ladder, thus encircling the flux twice. Mesoscopic devices that should enable one to observe these effects are proposed.

Mila, F; Capponi, S; Mila, Frederic; Stafford, Charles; Capponi, Sylvain

1998-01-01

280

A complete characterization of the spectrum of the Kitaev model on spin ladders  

CERN Document Server

We study the Kitaev model on a ladder network and find the complete spectrum of the Hamiltonian in closed form. Closed and manageable forms for all eigenvalues and eigenvectors, allow us to calculate the partition function and averages of non-local operators in addition to the reduced density matrices of different subsystems at arbitrary temperatures. It is also briefly discussed how these considerations can be generalized to more general lattices, including three-leg ladders and two dimensional square lattices.

Karimipour, Vahid

2009-01-01

 
 
 
 
281

The Short Call Ladder strategy and its application in trading and hedging  

Directory of Open Access Journals (Sweden)

Full Text Available The paper presents a new approach to the formation of Short Call Ladder (SCL strategy based on the functions of profit. Anoptimal algorithm for the use of this strategy in trading is introduced as well. Furthermore, this paper is focused on the applicationof Short Call Ladder strategy in hedging against a price rise of the underlying asset. In the end, the results are compared with theresults of hedging obtained by Short Combo and Vertical Ratio Call Back Spread option strategy.

Marcel Rešovský

2010-03-01

282

A Robust Embedded Ladder-Oxide/Cu Multilevel Interconnect Technology for 0.13 ?m Complementary Metal Oxide Semiconductor Generation  

Science.gov (United States)

A robust embedded ladder-oxide (k=2.9)/copper (Cu) multilevel interconnect is demonstrated for 0.13 ?m complementary metal oxide semiconductor (CMOS) generation. A stable ladder-oxide intermetal dielectric (IMD) is integrated by the Cu metallization with a minimum wiring pitch of 0.34 ?m, and a single damascene (S/D) Cu-plug structure is applied. An 18% reduction in wiring capacitance is obtained compared with that in SiO2 IMDs. The superior controllability of metal thickness by the S/D process enables us to enhance the MPU maximum frequency easily. The stress-migration lifetime of vias on wide metals for the S/D Cu-plug structure is longer than that for a dual damascene (D/D) structure. Reliability test results such as electromigration (EM), the temperature dependant dielectric breakdown (TDDB) of Cu interconnects, and pressure cooker test (PCT) results are acceptable. Moreover, a high flexibility in a thermal design is obtained.

Oda, Noriaki; Ito, Shinya; Takewaki, Toshiyuki; Shiba, Kazutoshi; Kunishima, Hiroyuki; Hironaga, Nobuo; Honma, Ichiro; Nanba, Hiroaki; Yokogawa, Shinji; Kameyama, Akiko; Goto, Takayuki; Usami, Tatsuya; Ohto, Koichi; Kubo, Akira; Suzuki, Mieko; Yamamoto, Yoshiaki; Watanabe, Susumu; Yamada, Kenta; Ikeda, Masahiro; Ueno, Kazuyoshi; Horiuchi, Tadahiko

2007-03-01

283

Petri Nets and Ladder Logic for Fully-Automating and Programmable Logic Control of Semi-Automatic Machines and Systems  

Directory of Open Access Journals (Sweden)

Full Text Available Problem statement: Automating semi-automatic dynamic machines and complex systems, where some functionalities are already automated but the machine doesn?t run fully in automatic mode, represents another challenge to automating dynamic and manual complex systems. This study deals with a special case of this general problem, where the system?s semi-automatic and automatic functionalities run separately in a sequence with either automatic and/or semi-automatic functionality running at any point of time, but not both. Approach: Petri-nets can successfully represent the operations of both the semi-automated and fully-automated functionalities of such dynamic systems. Three roles for the programmable logic controllers were suggested: (a Ignoring the presence of the semi-automatic part, (b simulating the semi-automatic part and recognizing discrepancies and(c simulating the semi-automatic functionalities and supporting it, where the last choice was most costly and most reliable. Results: This study presents a case study for a PVC mixing dynamic process to illustrate the three suggested controller design possibilities, where a Petri net model and related ladder logic program were developed to show these three controller design options. In this respect, the semiautomatic functionality is an intermediate step between the two automated functionalities, within which an important decision should be made to end the previous automatic step and to begin the next automatic step. Conclusion/Recommendations: The automation method that was introduced in this study is applicable to a large number of machines within industrial and mechanical systems that were built using older semi-automatic control systems. Various decision analyses {DA1, DA2, DA3} were shown to produce basic choices for such types of applications. Petri-nets and ladder logic in this respect can successfully represent the operations of both the semi-automated and fully-automated functionalities, where a Petri net model and the consequent ladder logic program, used to program the utilized programmable logic controller, are developed to show three possible controller designs, where the choice between three designs depend on the designers objective of cost, reliability and fault tolerance.

Mahmoud A. Barghash

2011-01-01

284

New approaches to all carbon ladder polymers: Cyclization reactions of acetylenes  

Energy Technology Data Exchange (ETDEWEB)

All-carbon conjugated ladder polymers promise to exhibit attractive electrical and optical properties. While a few very elegant synthesis of all-carbon ladder polymers (and oligomers) have been reported, it can be said that present synthetic procedures are insufficient to realize the true potential of this important class of material. The limited state of synthetic procedures stems from the inherent insolubility of ladder polymers which precludes standard synthetic methods. This paper reports herein the authors` investigations towards new synthetic routes to all-carbon ladder polymers with novel architectures by cyclization reactions of poly(1,2-denthynyl-phenylenes) and solid state polymerization of macrocyclic diacetylenes. High molecular weight (53,000-170,000) poly(1,2-diethynyl-phenylenes) have been synthesized by palladium catalyzed cross-coupling reactions. It is proposed that these materials may be converted to all-carbon ladder polymers by a zipper version of the Bergman cyclization reaction. A strained macrocylic diacetylene is reported which appears to undergo cyclo-polymerization in the solid state. This reaction also is being investigated as a route to all-carbon ladder polymers.

Zhou, Q.; Swager, T.M. [Univ. of Pennsylvania, Philadelphia, PA (United States)

1993-12-31

285

Field-induced incommensurate order in frustrated spin ladder  

International Nuclear Information System (INIS)

In the magnetization process of the S = 1/2 spin ladder system there are two critical magnetic fields Hc1 and Hc2. The spin gap vanishes at Hc1 and the magnetization is saturated at Hc2. Usually the commensurate antiferromagnetic spin correlation perpendicular to the external field H is dominant and the canted Neel order would be stabilized by interladder interaction for Hc1c2. The present theoretical study based on numerical diagonalization indicated the following interesting results. In the presence of the next-nearest-neighbour interaction, the incommensurate spin correlation parallel to H would be possibly stronger than the commensurate one for some intermediate external field. As a result, with interladder interaction, another field-induced transition would occur from the usual canted Neel order to the incommensurate one. The new field-induced transition is based on the so-called ?-inversion, namely a change from ?z>?x to ?zx, where ?z and ?x are the critical exponents of the parallel and perpendicular spin correlation functions, respectively. Some phase diagrams including the ?-inversion and the magnetization plateau are presented

286

Spin and charge modes of the t-J ladder  

International Nuclear Information System (INIS)

The spin and charge excitations of the t-J ladder are studied by exact diagonalization techniques for several electron densities. The various modes are classified according to their spin (singlet or triplet excitations) and their parity under a reflection with respect to the symmetry axis along the chains and a finite-size scaling of the related gaps is performed. At low doping, formation of hole pairs leads to a spin gap for all J/t ratios. This phase is characterized by (at least) one vanishing energy mode only in the charge bonding channel when Kx?0 consistent with the existence of superconducting pairing correlations. At larger doping the spin gap disappears. Although the antibonding modes remain gapped, low-energy Kx?0 and Kx?2kF spin and charge bonding modes are found consistent with a single-band Luttinger scenario. At sufficient low electron density and above a critical value of J/t we also expect another phase of electron pairs with gapped spin excitations

287

HST/WFC3 flux calibration ladder: Vega  

Science.gov (United States)

Vega is one of only a few stars calibrated against an SI-traceable blackbody, and is the historical flux standard. Photometric zeropoints of the Hubble Space Telescope's instruments rely on Vega, through the transfer of its calibration via stellar atmosphere models to the suite of standard stars. HST's recently implemented scan mode has enabled us to develop a path to an absolute SI traceable calibration for HST IR observations. To fill in the crucial gap between 0.9 and 1.7 micron in the absolute calibration, we acquired -1st order spectra of Vega with the two WFC3 infrared grisms. At the same time, we have improved the calibration of the -1st orders of both WFC3 IR grisms, as well as extended the dynamic range of WFC3 science observations by a factor of 10000. We describe our progress to date on the WFC3 `flux calibration ladder' project to provide currently needed accurate zeropoint measurements in the IR

Deustua, Susana E.; Bohlin, Ralph; Pirzkal, Nor; MacKenty, John

2014-08-01

288

Fish Allergy  

Science.gov (United States)

... read ingredient labels to identify fish ingredients. Salmon, tuna and halibut are the most common kinds of ... Pollock Salmon Scrod Swordfish Sole Snapper Tilapia Trout Tuna Some Unexpected Sources of Fish* Caesar salad and ...

289

Theoretical study of anisotropic mobility in ladder-type molecule organic semiconductors  

Science.gov (United States)

The properties of two ladder-type semiconductors {M1: 2,2'-(2,7-dihexy1-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-4,9-diylidene) dimalononitrile and M2: 2,7-dihexy1-4,9-dihydro- s-indaceno[1,2- b:5,6- b']dithiophene-4,9-dione} as the n-type and ambipolar organic materials are systematically investigated using the first-principle density functional theory combined with the Marcus-Hush electron transfer theory. It is found that the substitution of M1 induces large changes in its electron-transfer mobility of 1.370 cm2 V-1 s-1. M2 has both large electron- and hole-transfer mobility of 0.420 and 0.288 cm2 V-1 s-1, respectively, which indicates that M2 is potentially a high efficient ambipolar organic semiconducting material. Both the M1 and M2 crystals show remarkable anisotropic behavior. A proper design of the n-type and ambipolar organic electronic materials, which may have high mobility performance, is suggested based on the investigated two molecules.

Wei, Hui-Ling; Liu, Yu-Fang

2014-09-01

290

Equivalence of particle-particle random phase approximation correlation energy and ladder-coupled-cluster doubles.  

Science.gov (United States)

The recent proposal to determine the (exact) correlation energy based on pairing matrix fluctuations by van Aggelen et al. ["Exchange-correlation energy from pairing matrix fluctuation and the particle-particle random phase approximation," preprint arXiv:1306.4957 (2013)] revived the interest in the simplest approximation along this path: the particle-particle random phase approximation (pp-RPA). In this paper, we present an analytical connection and numerical demonstrations of the equivalence of the correlation energy from pp-RPA and ladder-coupled-cluster doubles. These two theories reduce to identical algebraic matrix equations and correlation energy expressions. The numerical examples illustrate that the correlation energy missed by pp-RPA in comparison with coupled-cluster singles and doubles is largely canceled out when considering reaction energies. This theoretical connection will be beneficial to design density functionals with strong ties to coupled-cluster theories and to study molecular properties at the pp-RPA level relying on well established coupled cluster techniques. PMID:24050333

Peng, Degao; Steinmann, Stephan N; van Aggelen, Helen; Yang, Weitao

2013-09-14

291

Bony Fishes  

Science.gov (United States)

Sea World informational resource on bony fishes. Excellent introduction to bony fishes including information on their classification, habitat, physical characteristics, diet, reproduction, and much more. Includes photographs and illustrations throughout, and features a spreadsheet showing the different subclasses and the number of species found within each. Site also provides a comprehensive list of books about bony fishes for the younger reader.

292

Ashlu Creek hydroelectric project: Design and optimization of hydraulic structures under construction using 2D and 3D numerical modeling  

Energy Technology Data Exchange (ETDEWEB)

A hydroelectric project located on Ashlu Creek, halfway between Whistler and Vancouver in British Columbia, consisted of a run-of-river project that used a short stretch of steep rapids to generate a capacity of 49.9MW. This paper presented the design and the optimization of the hydraulic structures during the construction phases using 2-D and 3-D numerical modelling. The proposed works included an emergency spillway weir equipped with an Obermeyer gate, a rock-fill weir, a Denil type fish ladder, a sluiceway and a side intake. The design and the verification of the upstream works were carried out using these models. The hydraulic conditions during construction phases were also simulated using the models in order to estimate the impact of the operations and validate the diversion works. It was found that numerical modeling can be an efficient alternative to small-scale physical modeling for specific applications in designing hydraulic structures.

Briand, Marie-Helene; Tremblay, Catherine; Bosse, Yannick; Gacek, Julian; Alfaro, Carola [RSW Inc., (Canada); Blanchet, Richard [Innergex Renewable Energy, Vancouver, (Canada)

2010-07-01

293

Hood River Pelton Ladder evaluation studies: Annual report 1995  

International Nuclear Information System (INIS)

Data collected from this program will provide the baseline information needed to (1) evaluate various management options for implementing the Hood River Production Plan and (2) determine any post-project impacts the Hood River Production Plan has on indigenous populations of resident fish

294

Considerations for Dynamic Temperature Compensation of Wideband Ladder-type SAW Filter  

Science.gov (United States)

Because of there excellent features such as small-size, wide bandwidth, and low insertion loss, the ladder-type filters based on surface acoustic wave (SAW) technology have been widely used as radio-frequency (RF) filters in mobile communications. We can make wide bandwidth, and low insertion loss, the ladder-type SAW filters on a Cu-grating/15°LiNbO3 substrate structure. On the other hand, it is said that wide bandwidth filters is bad temperature characteristic. So this paper discusses dynamic temperature compensation of wideband ladder-type SAW filters. First, we investigate how wide tunability is achievable using variable capacitors parallel- and/or series-connectted to SAW resonators in the filter configuration. Second, we measured the temperature characteristic of resonator. Finally, we simulated temperature compensation of wideband ladder-type SAW filters. As a result, we were able to compensate the change of the characteristic with the ladder-type SAW filter connected variable capacitors.

Nakamura, Nobuyuki; Komatsu, Tomoya; Omori, Tatsuya; Hashimoto, Ken-Ya; Yamaguchi, Masatsune

295

Doped spin ladders under magnetic field; Echelles de spins dopees sous champ magnetique  

Energy Technology Data Exchange (ETDEWEB)

This thesis deals with the physics of doped two-leg ladders which are a quasi one-dimensional and unconventional superconductor. We particularly focus on the properties under magnetic field. Models for strongly correlated electrons on ladders are studied using exact diagonalization and density-matrix renormalization group (DMRG). Results are also enlightened by using the bosonization technique. Taking into account a ring exchange it highlights the relation between the pairing of holes and the spin gap. Its influence on the dynamics of the magnetic fluctuations is also tackled. Afterwards, these excitations are probed by the magnetic field by coupling it to the spin degree of freedom of the electrons through Zeeman effect. We show the existence of doping-dependent magnetization plateaus and also the presence of an inhomogeneous superconducting phase (FFLO phase) associated with an exceeding of the Pauli limit. When a flux passes through the ladder, the magnetic field couples to the charge degree of freedom of the electrons via orbital effect. The diamagnetic response of the doped ladder probes the commensurate phases of the t-J model at low J/t. Algebraic transverse current fluctuations are also found once the field is turned on. Lastly, we report numerical evidences of a molecular superfluid phase in the 3/2-spin attractive Hubbard model: at a density low enough, bound states of four fermions, called quartets, acquire dominant superfluid fluctuations. The observed competition between the superfluid and density fluctuations is connected to the physics of doped ladders. (author)

Roux, G

2007-07-15

296

Experiments on Ladders Reveal a Complex Interplay between a Spin-Gapped Normal State and Superconductivity  

CERN Document Server

In recent years, the study of ladder materials has developed into a well-established area of research within the general context of Strongly Correlated Electrons. This effort has been triggered by an unusual cross-fertilization between theory and experiments. In this paper, the main experimental results obtained in the context of ladders are reviewed from the perspective of a theorist. Emphasis is given to the many similarities between the two-dimensional high-$\\rm T_c$ cuprates and the two-leg ladder compounds, including Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ (14-24-41) which has a superconducting phase at high pressure and a small hole density. Examples of these similarities include regimes of linear resistivity vs temperature in metallic ladders and a normal state with spin-gap or pseudogap characteristics. Some controversial results in this context are also discussed. It is remarked that the ladder 14-24-41 is the first superconducting copper-oxide material with a non-square-lattice layered arrangement, and c...

Dagotto, E

1999-01-01

297

Three-photon electromagnetically induced absorption in a ladder-type atomic system  

Science.gov (United States)

We report on three-photon electromagnetically induced absorption (TPEIA) due to three-photon coherence in ladder-type atomic systems for the 5S1/2-5P3/2-5D5/2 transition in 87Rb atoms. When a counterpropagating coupling field was added to the typical ladder-type electromagnetically induced transparency (EIT) experiment, both EIT and two-photon absorption (TPA) switched to TPEIA. Considering three-photon coherence in a Doppler-broadened three-level ladder-type atomic system, the spectrum of the switch from EIT and TPA to TPEIA was numerically calculated and could be understood by decomposing the calculated spectrum into two-photon coherence and three-photon coherence components.

Moon, Han Seb; Jeong, Taek

2014-03-01

298

High-energy, large-momentum-transfer processes: Ladder diagrams in var-phi 3 theory  

International Nuclear Information System (INIS)

Relativistic quantum field theories may help one to understand high-energy, large-momentum-transfer processes, where the center-of-mass energy is much larger than the transverse momentum transfers, which are in turn much larger than the masses of the participating particles. With this possibility in mind, the author studies ladder diagrams in var-phi 3 theory. He shows that in the limit s much-gt |t| much-gt m2, the scattering amplitude for the N-rung ladder diagram takes the form s-1|t|-N+1 times a homogeneous polynomial of degree 2N - 2 and ln s and ln |t|. This polynomial takes different forms depending on the relation of ln |t| to ln s. More precisely, the asymptotic formula for the N-rung ladder diagram has points of non-analytically when ln |t| = ? ln s for ? = 1/2, 1/3, hor-ellipsis, 1/N-2

299

Determination of selenium in fish from designated critical habitat in the Gunnison River, Colorado, March through October, 2012  

Science.gov (United States)

This report presents results for the summer 2012 sam-pling of muscle plugs from common carp (Cyprinus carpio), bonytail chub (Gila elegans), Colorado pikeminnow (Ptycho-cheilus lucius), and razorback suckers (Xyrauchen texanus) inhabiting critical habitat in the Gunnison River in western Colorado. Total selenium in fish muscle plugs was determinedby instrumental neutron activation analysis. Total selenium concentrations (range and mean ± standard deviation) in micrograms per gram dry weight were 6.0 to 10.7, 8.8 ± 1.3 for common carp; 2.9 to 8.7, 5.6 ± 2.4 for Colorado pikemin-now; and 1.4 to 7.3, 3.4 ± 2.7 for razorback sucker. The selenium concentration for one bonytail chub sample was 0.8 micrograms per gram dry weight. Selenium concentrations in muscle plugs from 1 Colorado pikeminnow and 12 common carp exceeded the 8 micrograms per gram dry weight toxicity guideline for selenium in fish muscle tissue.

May, Thomas W.; Walther, Michael J.

2013-01-01

300

The ladder mill. A high variant of the traditional windmill; De laddermolen. Een kilometershoge variant op de traditionele windmolen  

Energy Technology Data Exchange (ETDEWEB)

Despite the decreasing price difference, electricity from wind turbines is still considerably more expensive than electricity generated from fossil fuels. The ladder mill, an invention by the brothers Jan Hendrik Ockels and Wubbo Ockels, can change that situation in one stroke. A brief overview is given of the principles of the ladder mills a revolution in wind energy in the air?.

Ockels, W. [O-Mill BV, Aerdenhout (Netherlands)

1998-05-01

 
 
 
 
301

Shoulder muscle loading and task performance for overhead work on ladders versus Mobile Elevated Work Platforms.  

Science.gov (United States)

A high incidence of Musculoskeletal Disorders (MSDs) has been reported in the construction sector. The use of ladders in the workplace has long been identified as a significant risk that can lead to workplace accidents. However, it is unclear if platform types have an effect on the physical risk factors for MSDs in overhead work. The aim of this study is to perform a pilot study on the effects of hand activity on both shoulder muscle loading and task performance while working on ladders versus Mobile Elevated Working Platforms (MEWPs). It is hypothesised that work on ladders would result in greater muscle loading demands, increased levels of discomfort, and reduced performance due to the restrictions on postures that could be adopted. A field study (n = 19) of experienced electricians on a construction site found that workers spent approximately 28% of their working time on ladders versus 6% on MEWPs. However, the durations of individual tasks were higher on MEWPs (153 s) than on ladders (73 s). Additionally, maximum levels of perceived discomfort (on a VAS 0-100) were reported for the shoulders (27), neck (23), and lower regions of the body (22). A simulated study (n = 12) found that task performance and discomfort were not significantly different between platform types (ladder vs. MEWP) when completing either of three tasks: cabling, assembly and drilling. However, platform and task had significant effects (p < 0.05) on median electromyographic (EMG) activity of the anterior deltoid and upper trapezius. EMG amplitudes were higher for the deltoid than the upper trapezius. For the deltoid, the peak amplitudes were, on average, higher for ladder work over MEWP work for the hand intensive cabling (32 vs. 27% Maximal Voluntary Exertion (MVE)) and the assembly task (19 vs. 6% MVE). Conversely, for drilling, the peak EMG amplitudes were marginally lower for ladder compared to the MEWP (3.9 vs. 5.1% MVE). The general implication was that working on the MEWP involved lower shoulder muscle loading for cabling and assembly task. A difference due to platform type was not present for drilling work. PMID:24768091

Phelan, Denis; O'Sullivan, Leonard

2014-11-01

302

Electric field induced localization phenomena in a ladder network with superlattice configuration: Effect of backbone environment  

Directory of Open Access Journals (Sweden)

Full Text Available Electric field induced localization properties of a tight-binding ladder network in presence of backbone sites are investigated. Based on Green's function formalism we numerically calculate two-terminal transport together with density of states for different arrangements of atomic sites in the ladder and its backbone. Our results lead to a possibility of getting multiple mobility edges which essentially plays a switching action between a completely opaque to fully or partly conducting region upon the variation of system Fermi energy, and thus, support in fabricating mesoscopic or DNA-based switching devices.

Paramita Dutta

2014-09-01

303

Zero energy Majorana modes in spin ladders and a possible realization of the Kitaev model  

CERN Document Server

We show that in double-chain Mott insulators (ladders), disordered alternating ionic potentials may locally destroy coherence of magnetic excitations and lead to the appearance of spontaneously dimerized islands inside the Haldane spin-liquid phase. We argue that a boundary between the dimerized and Haldane phases of a spin-1/2 ladder supports a localized zero-energy Majorana fermion mode. Based on these findings we suggest a realization of a generalized Kitaev model where Majorana fermions can propagate in more than one dimension.

Nersesyan, A A

2011-01-01

304

High-energy, large-momentum-transfer processes: Ladder diagrams in ?3 theory. Pt. 1  

International Nuclear Information System (INIS)

Relativistic quantum field theories may give us useful guidance to understanding high-energy, large-momentum-transfer processes, where the center-of-mass energy is much larger than the transverse momentum transfers, which are in turn much larger than the masses of the participating particles. With this possibility in mind, we study the ladder diagrams in ?3 theory. In this paper, some of the necessary techniques are developed and applied to the simplest cases of the fourth- and sixth-order ladder diagrams. (orig.)

305

Linearized coherent states for Hamiltonian systems with two equidistant ladder spectra  

Science.gov (United States)

A simple way to construct exactly solvable Hamiltonians whose spectra contain two equidistant ladders, one finite and another infinite, appears when applying supersymmetric quantum mechanics to the harmonic oscillator. Some of those supersymmetric partners have third order differential ladder operators, although the order of the transformation is higher than one. In this work the linearized coherent states for these specific Hamiltonians are studied. To each SUSY partner Hamiltonian corresponds two families of linearized coherent states: one inside the subspace associated with the isospectral part of the spectrum and another one in the finite subspace generated by the states inserted through the SUSY technique.

Bermudez, D.; Contreras-Astorga, A.; Fernández C, D. J.

2014-05-01

306

A Novel Approach to Reliability Analysis Using Petri Nets and Ladder Logic Diagrams  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract— In this paper the dynamic modeling of repairable and standby components of complex systems is analyzed using Petri Nets and ladder logic diagrams. The use of Petri Nets as modelling of a complex system avoids two basic disadvantages of Markov chain analysis. First, the Petri Net model does not grow in size as increasing the number of components and second, Markov chain has been limited to the exponential probability distribution. PetriLLD software is used for building Petri Net models and then the Petri Net models are converted to ladder logic diagrams for reliability analysis.

Majid Pakdel and Kazem Mazlumi

2014-03-01

307

Equivalence of Particle-Particle Random Phase Approximation Correlation Energy and Ladder-Coupled-Cluster-Double  

CERN Document Server

We present an analytical proof and numerical demonstrations of the equivalence of the correlation energy from particle-particle random phase approximation (pp-RPA) and ladder-couple-cluster-doubles (ladder-CCD). These two theories reduce to the identical algebraic matrix equation and correlation energy expressions, under the assumption that the pp-RPA equation is stable. The numerical examples illustrate that the correlation energy missed by pp-RPA in comparison with couple-cluster single and double is largely canceled out when considering reaction energies. This theoretical connection will be beneficial to future pp-RPA studies based on the well established couple cluster theory.

Peng, Degao; van Aggelen, Helen; Yang, Weitao

2013-01-01

308

Diagrammatic analysis of multiphoton processes in a ladder-type three-level atomic system  

Energy Technology Data Exchange (ETDEWEB)

We present a diagrammatic method for complete characterization of multiphoton processes in three-level atomic systems. By considering the interaction routes of the coupling and probe photons for a ladder-type, three-level, noncycling (or cycling) atomic system, we are able to completely discriminate between the pure one-photon and the pure two-photon resonance effects, and the effect of their combination in electromagnetically induced transparency (EIT) using our diagrammatic method. We show that the proposed diagrammatic method is very useful for the analysis of multiphoton processes in ladder-type EIT.

Noh, Heung-Ryoul [Department of Physics, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Moon, Han Seb [Department of Physics, Pusan National University, Busan 609-735 (Korea, Republic of)

2011-11-15

309

Universal finite-size corrections of the entanglement entropy of quantum ladders and the entropic area law  

Science.gov (United States)

We investigate the finite-size corrections of the entanglement entropy of critical ladders and propose a conjecture for its scaling behaviour. The conjecture is verified for free fermions, for Heisenberg ladders, and for quantum Ising ladders. Our results support that the prefactor of the logarithmic correction of the entanglement entropy of critical ladder models is universal and is associated with the central charge of the one-dimensional version of the models and with the number of branches associated with gapless excitations. Our results suggest that it is possible to infer whether there is a violation of the entropic area law in two-dimensional critical systems by analyzing the scaling behaviour of the entanglement entropy of ladder systems, which are easier to deal with.

Xavier, J. C.; Ramos, F. B.

2014-10-01

310

An Evaluation of the Selectivity Characteristics of Different Juvenile Fish Escape Panel Designs for the Demersal Trap Fishery of Abu Dhabi, United Arab Emirates  

Directory of Open Access Journals (Sweden)

Full Text Available The selectivity characteristics of 4 juvenile fish escape panel designs and their utility for the regulation of a multi-species demersal trap fishery were evaluated using a suite of objective socio-economic and biological criteria. The panel designs consisted of a control (type A which had a hexagonal mesh size which was the same as that of the body of the trap (3.5 cm, a rectangular mesh (type B which was representative of the current regulation (5.0 x 7.6 cm and 2 escape panels with square meshes of 7.5 x 7.5 cm (type C and 10.0 x 10.0 cm (type D. The results demonstrated that there was only a limited reduction in the proportion of juvenile fish and by-catch retained for the existing juvenile escape panel design (type B. Furthermore, as the selectivity characteristics for the key species (Epinephelus coioides and Diagramma pictum were similar to the control type, the predicted increases in yields, revenues and spawning stock biomass were small by comparison. The escape panel with the largest mesh size (type D retained the least un-utilized and discarded by-catch. Whilst simulations predicted the highest spawner biomass per recruit, long term yields and revenues for the key species, its use was associated with a dramatic short-term decline in revenues which were 23.3% of the value of the control type. Traps fitted with the type C which had a square mesh of 7.5 x 7.5 cm had the lowest juvenile retention and the highest overall score for all the assessment criteria combined. The study provides an empirical basis for gear regulations for the demersal trap fishery of the Emirate of Abu Dhabi and the wider Arabian Gulf region.

Edwin Mark Grandcourt

2011-10-01

311

Benefits of fish passage and protection measures at hydroelectric projects  

International Nuclear Information System (INIS)

The US Department of Energy's Hydropower Program is engaged in a multi-year study of the costs and benefits of environmental mitigation measures at nonfederal hydroelectric power plants. An initial report (Volume 1) reviewed and surveyed the status of mitigation methods for fish passage, instream flows, and water quality; this paper focuses on the fish passage/protection aspects of the study. Fish ladders were found to be the most common means of passing fish upstream; elevators/lifts were less common, but their use appears to be increasing. A variety of mitigative measures is employed to prevent fish from being drawn into turbine intakes, including spill flows, narrow-mesh intake screens, angled bar racks, and lightor sound-based guidance measures. Performance monitoring and detailed, quantifiable performance criteria were frequently lacking at non-federal hydroelectric projects. Volume 2 considers the benefits and costs of fish passage and protection measures, as illustrated by case studies for which performance monitoring has been conducted. The report estimates the effectiveness of particular measures, the consequent impacts on the fish populations that are being maintained or restored, and the resulting use and non-use values of the maintained or restored fish populations

312

Venomous Fish  

Science.gov (United States)

While most fish are completely harmless to people, there are some species that are mildly to extremely venomous and can actually kill humans. In this video, Jonathan travels the world to meet some of the most venomous fish in the sea. Please see the accompanying study guide for educational objectives and discussion points.

Productions, Jonathan B.

2010-08-10

313

Use of DNA ladders for reproducible protein fractionation by SDS-PAGE for quantitative proteomics  

Science.gov (United States)

In proteomics, one-dimensional (1D) SDS-PAGE is widely used for protein fractionation prior to mass spectrometric analysis to enhance dynamic range of analysis and to improve identification of low-abundance proteins. Such protein pre-fractionation works well for quantitation strategies if the proteins are labeled prior to separation. However, due to the poor reproducibility of cutting gel slices, especially when small amounts of samples are analyzed, its application in label-free and peptide labeling quantitative proteomics methods has been greatly limited. To overcome this limitation, we developed a new strategy in which a DNA ladder is mixed with the protein sample before PAGE separation. After PAGE separation, the DNA ladder is stained to allow for easy, precise and reproducible gel cutting. To this end, a novel visible DNA staining method was developed. This staining method is fast, sensitive and compatible with mass spectrometry. To evaluate the reproducibility of DNA ladder assisted gel cutting for quantitative protein fractionation, we used SILAC (stable isotope labeling with amino acids in cell culture). Our results show that the quantitative error associated with fractionation can be minimized by using the DNA assisted fractionation and multiple replicates of gel cutting. In conclusion, 1D PAGE fractionation in combination with DNA ladders can be used for label-free comparative proteomics without compromising quantitation. PMID:18189343

Zhang, Guoan; Fenyo, David; Neubert, Thomas A.

2009-01-01

314

Career Ladders and the Professionalization of Teaching: Down the Up Staircase.  

Science.gov (United States)

School systems interested in improving teacher performance, effectiveness, and job satisfaction while reducing turnover rates might do better to seek ways to enhance the intrinsic rewards of teaching rather than implement such extrinsic motivators as merit pay plans and career ladders. A review of the research literature brings several important…

Dunwell, Robert R.

315

Means-end chains and laddering: An inventory of problems and an agenda for research  

DEFF Research Database (Denmark)

Laddering and means-end chains are one of the most promising developments in consumer research since the 1980s. It is an approach that takes consumers' individuality seriously but, nevertheless, comes up with quantitative results. It is rooted in a cognitive approach, and allows for emotional and unconscious (or, at least, semiconscious) factors. It is intuitively appealing to the practitioner but has, likewise, attracted academic research. Increased acceptance and use of a new approach inevitably leads to the detection of unresolved issues and problems. Many of these unresolved issues are related to the collection and analysis of laddering data. However, many of these also point at problems of a more theoretical nature. In this chapter presented are some of the issues regarded as unresolved and suggested research that could help in solving these problems. The mayor part of this chapter deals with methodological problems of the interview technique called laddering, og coding laddering data, and of analysing the coded data. However, also shown, methodological and theoretical issues are partly interlinked: resolutions of methodological problems may require theoretical progress or at least a clarification of some theoretical issues. We therefore start with a discussion of some unresolved theoretical issues.

Grunert, Klaus G.; Beckmann, Suzanne C.

2001-01-01

316

Jacob's ladders and the tangent law for short parts of the Hardy-Littlewood integral  

CERN Document Server

The elementary geometric properties of the Jacob's ladders \\cite{7} lead to a class of new formulae for short parts of the Hardy-Littlewood integral. This class of formulae cannot be obtained by methods of Balasubramanian, Heath-Brown and Ivic.

Moser, Jan

2009-01-01

317

Jacob's ladders and the quantization of the Hardy-Littlewood integral  

CERN Document Server

We use Jacob's ladders to solve the fine problem how to divide of the Hardy-Littlewood integral to equal parts, for example of magnitude $h=6.6\\times 10^{-27}$ (the numerical value of elementary Planck quantum). The result of the paper cannot be obtained in known theories of Balasubramanian, Heath-Brown and Ivic.

Moser, Jan

2009-01-01

318

Theory of bosons in two-leg ladders with large magnetic fields  

Science.gov (United States)

We calculate the ground state of a Bose gas trapped on a two-leg ladder where Raman-induced hopping mimics the effect of a large magnetic field. In the mean-field limit, where there are large numbers of particles per site, this maps onto a uniformly frustrated two-leg ladder classical spin model. The net particle current always vanishes in the ground state, but generically there is a finite "chiral current," corresponding to equal and opposite flow on the two legs. We vary the strength of the hopping across the rungs of the ladder and the interaction between the bosons. We find the following three phases. (1) A "saturated chiral current phase" (SCCP), where the density is uniform and the chiral current is simply related to the strength of the magnetic field. In this state the only broken symmetry is the U(1) condensate phase. (2) A "biased ladder phase" (BLP), where the density is higher on one leg than the other. The fluid velocity is higher on the lower density leg, so the net current is zero. In addition to the U(1) condensate phase, this has a broken Z2 reflection symmetry. (3) A "modulated density phase" (MDP), where the atomic density is modulated along the ladder. In addition to the U(1) condensate phase, this has a second broken U(1) symmetry corresponding to translations of the density wave. We further study the fluctuations of the condensate in the BLP, finding a roton-maxon-like excitation spectrum. Decreasing the hopping along the rungs softens the spectrum. As the energy of the "roton" reaches to zero, the BLP becomes unstable. We describe the experimental signatures of these phases, including the response to changing the frequency of the Raman transition.

Wei, Ran; Mueller, Erich J.

2014-06-01

319

Isomeric DNA ladder formation of a plasmid encoding tobramycin resistance from Escherichia coli.  

Science.gov (United States)

During a 20-month survey of resistance to three aminoglycosides (gentamicin, tobramycin, and amikacin) in Escherichia coli at a university hospital, six tobramycin-, kanamycin-resistant isolates containing a 50 kilobase conjugative R-plasmid which encoded an aminoglycoside phosphotransferase (APH-(3')) were isolated. The APH-(3') conferred resistance to kanamycin (MIC = 100 mg/L) but not to tobramycin (MIC = 20 mg/L). In both the original isolates and transconjugants the six R-plasmids demonstrated an isomeric ladder in the range of 50-112 kb, which was enhanced by exposure of the bacterial cultures to tobramycin. pJFJ2522 is the prototype for this group of plasmids. Bacterial DNA gyrase reversed the isomeric DNA ladder in pJFJ25222 by increasing the supercoiling of the plasmid DNA. Regardless of the level of supercoiling, the plasmids produced indistinguishable restriction endonuclease fragment patterns. The clinical isolates containing these plasmids demonstrated different restriction fragment length polymorphism (RFLP) of their EcoRI digested genomic DNA using E. coli rRNA as a probe. Ladder formation was plasmid specific since other tobramycin R-plasmids did not form a ladder, but it was not host specific. pJFJ25222 formed a ladder in a recA- host and displayed the same restriction pattern in a recA- as in a recA+ environment. In conclusion, pJFJ2522 contains a new tobramycin resistance gene whose mechanism of resistance is not known and whose product probably influences the isomerization of the plasmid. PMID:1685732

Singh, M; John, J F

1991-11-01

320

Effects of aluminum trichloride and magnesium chloride on the synthesis of ladder polyphenylsilsesquioxane  

Directory of Open Access Journals (Sweden)

Full Text Available Ladder polyphenylsilsesquioxane (Ph-LPSQ has been synthesized at 80°C through the hydrolysis and condensation of phenyltrichlorosilane (PhSiCl3, with aluminum chloride (AlCl3 or magnesium chloride (MgCl2 as an assistant reactant. The Ph-LPSQ obtained has been characterized and analyzed by SEM, FTIR, TGA, 29Si NMR, and MALDI-TOF MS, and the effects of AlCl3and MgCl2on the structure regularity of Ph-LPSQ and the condensation polymerizationhavealso been studied. The results showed that Ph-LPSQ could be obtained in theAlCl3and MgCl2systems, respectively, but the experimental phenomena and results showed significant differences between the two systems. SEM observation revealed spherical Ph-LPSQ particles from the PhSiCl3/AlCl3system, but irregular and agglomerated Ph-LPSQ particles from the PhSiCl3/1.5(MgCl2 system. TGA, 29SiNMR, and MALDI-TOF MS indicated that the ladder structure of Ph-LPSQ from the PhSiCl3/1.5(MgCl2 system was more regular. Inthe PhSiCl3/AlCl3system, Al could be incorporated into the ladder chain structure through competing reactions between Si-O-Al and Si-O-Si, which slightly decreased the regularity of the ladder chain structure of Ph-LPSQ. Mechanistic analysis suggests that the presence of AlCl3or MgCl2in the hydrolysis and condensation system favors the intermolecular condensation of intermediate products of polyhydroxyl silanol to form a regular ladder structure.

Jiang Yunyun

2012-01-01

 
 
 
 
321

Do Fish Enhance Tank Mixing?  

DEFF Research Database (Denmark)

The design of fish rearing tanks represents a critical stage in the development of optimal aquaculture systems, especially in the context of recirculating systems. Poor hydrodynamics can compromise water quality, waste management and the physiology and behaviour of fish, and thence, production potential and operational profitability. The hydrodynamic performance of tanks, therefore, represents an important parameter during the tank design process. Because there are significant complexities in combining the rigid principles of hydrodynamics with the stochastic behaviour of fish, however, most data upon tank hydrokinetics has been derived using tanks void of fish. Clearly, the presence of randomly moving objects, such as fish, in a water column will influence not only tank volumes by displacing water, but due to their activity, water dynamics and associated in-tank processes. In order to determine the impact of fish presence upon tank hydrodynamics, Rhodamine fluorometry was employed to examine mixing within a recirculating aquaculture system. Two different methods were compared, traditional, outlet-based measurements and a technique that employed in-tank data acquisition. Circular tanks were employed during data collection either in the presence or absence of xperimental fish-red drum Sciaenops ocellatus (n =36; 5 kg total wet wt); and at two flow rates. Irrespective of flow rate, the presence of fish dramatically enhanced the mixing process ( P< 0.001), with mixing times in tanks with fish being one-third that for tanks without animals. In-tank dispersion coefficients and dispersion numbers also differed ( P b0.001) in the presence of fish, irrespective of flow. Presence or absence of fish had no effect upon hydraulic residence or circulation times. Unlike measurements at the outlet, in-tank observations were more able to isolate the effects of stochastic, fish-induced mixing, from deterministic, hydrodynamic mixing.

Rasmussen, Michael R.; Laursen, Jesper

2005-01-01

322

Exact Ground States of Frustrated Spin-1 Ising-Heisenberg and Heisenberg Ladders in a Magnetic Field  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ground states of the frustrated spin-1 Ising-Heisenberg two-leg ladder with Heisenberg intra-rung coupling and only Ising interaction along legs and diagonals are rigorously found by taking advantage of local conservation of the total spin on each rung. The constructed ground-state phase diagram of the frustrated spin-1 Ising-Heisenberg ladder is then compared with the analogous phase diagram of the fully quantum spin-1 Heisenberg two-leg ladder obtained by density matrix re...

Strecka, Jozef; Michaud, Frederic; Mila, Frederic

2013-01-01

323

Career Ladder and Curriculum Guide. Entry Position: Code Enforcement Aide, Mid-Level Position: Code Enforcement Inspector I, Goal Position: Code Enforcement Inspector II; Entry Position: Zoning Inspector Aide, Mid-Level Position: Zoning Inspector I, Goal Position: Zoning Inspector II. Instructor's Manual.  

Science.gov (United States)

This instructor's manual contains two independent "volumes," Career Ladder and Curriculum Guides to Code Positions and Zoning Positions. Each guide is structured representing the progression of required and/or suggested training needed to progress from entry to journeyman levels in the requisite occupational field. The training designs are…

Department of Housing and Urban Development, Washington, DC.

324

Multiple Robotic Fish’s Target Search and Cooperative Hunting Strategies  

Directory of Open Access Journals (Sweden)

Full Text Available Multi-robotic fish’s cooperative hunting is through that the robotic fish groups’ collaboration and against, ultimately achieves the purpose of encirclement target; there is important significance to realize security of the underwater group. This paper studied the problem of multi-robotic fish’s target search and cooperative hunting, discussed on the multi-robotic fish’s group size, conditions of search target and hunting successful, conditions of failure successfully. Proposed the partition global search strategy, hunt-robotic fish use a hunting strategy that based on dynamic surrounding point, and designed intelligent escape strategy for invasion-robotic fish. A simulation experience is conducted to verify the hunting strategy and escape strategy that proposed in this paper, and the results show that on the basic of fast search to the target, multi-robotic fishes can achieve hunting task efficiently, but also reflects the game against behavior between the intruders and hunters.     Keywords:

Da Lin

2013-07-01

325

Fish oil  

Science.gov (United States)

... with this combination.Talk with your health provider.Orlistat (Xenical, Alli)Orlistat (Xenical, Alli) might keep the beneficial fatty acids ... absorbed by the body. Taking fish oil and orlistat (Xenical, Alli) at least 2 hours apart may ...

326

Fish cognition.  

Science.gov (United States)

The central nervous system, and the brain in particular, is one of the most remarkable products of evolution. This system allows an individual to acquire, process, store and act on information gathered from the environment. The resulting flexibility in behavior beyond genetically coded strategies is a prime adaptation in animals. The field of animal cognition examines the underlying processes and mechanisms. Fishes are a particularly interesting group of vertebrates to study cognition for two reasons (Figure 1). First, they occupy a key position in the vertebrate phylogenetic tree: the common ancestor of the tetrapods was a bony fish. Thus, all vertebrates share key genetic features that code for the body structure, including the vertebrate brain. Similarities in brain structure and function are hence likely to be due to common ancestry. A second reason to study fish cognition is that fish have had their own independent evolution/radiation since they split from tetrapods. Bony fishes are by far the most species-rich vertebrate group. As a consequence, they provide the best options for a comparative approach that aims to link the evolution of cognition to a species' ecology. Therefore, the study of fishes may reveal general principles of ecological effects on cognitive abilities in vertebrates. PMID:25291632

Bshary, Redouan; Brown, Culum

2014-10-01

327

Alkylphenols, Other Endocrine-Active Chemicals, and Fish Responses in Three Streams in Minnesota - Study Design and Data, February-September 2007  

Science.gov (United States)

This report presents the study design and environmental data for an integrated chemical and biological study of three streams (South Fork Crow River, Redwood River, and Grindstone River) that receive wastewater in Minnesota. The objective of the study was to identify distribution patterns of endocrine-active chemicals and other organic chemicals indicative of wastewater, and to identify fish responses in the same streams. Endocrine-active chemicals are a class of chemicals that interfere with the natural regulation of endocrine systems, and an understanding of their distribution in aquatic systems is important so that aquatic organism exposure can be evaluated. This study was a cooperative effort of the U.S. Geological Survey (USGS), the Minnesota Pollution Control Agency, and St. Cloud State University (St. Cloud, Minn.). The USGS collected and analyzed water and quality-assurance samples and measured streamflow during six sampling events in each of three streams. Water samples were collected upstream from and at two successive points downstream from wastewater-treatment plant (WWTP) effluent discharge and from treated effluent from February through September 2007. Bed-sediment samples were collected during one sampling period at each of the stream locations. Water and bed-sediment samples were analyzed for endocrine-active chemicals including alkylphenols, alkylphenol polyethoxylates, and nonylphenol ethoxycarboxlylates (NPECs). Water samples also were analyzed for major ions, nutrients, and organic carbon. In addition, as part of an intensive time-series investigation, the USGS staff collected daily water samples for 8 weeks from the Redwood River near Marshall, Minn., for analyses of total alkylphenols and atrazine. St. Cloud State University staff collected and analyzed fish to determine male fish responses at all water sampling sites and at an additional site near the discharge of wastewater-treatment plant effluent to these streams. Male fish responses included the presence and concentration of vitellogenin in plasma, gonadosomatic indices, and histological characterizations of liver and testes tissue. Hydrologic, chemical and biological characteristics were different among sites. The percentage of streamflow contributed by WWTP effluent (ranging from less than 1 to 79 percent) was greatest at the South Fork Crow River and least at the Grindstone River. WWTP effluent generally contributed the greatest percentage of streamflow during winter and late summer when streamflows were low. A wide variety of chemicals were detected. More chemicals were detected in WWTP effluent samples than in stream samples during most time periods. The most commonly detected chemicals in samples collected monthly and analyzed at the USGS National Research Program Laboratory were 2,6-di-tert-butyl-1,4-benzoquinone, 2,6-di-tert-butyl-4-methylphenol, 3-beta-coprostanol, 4-methylphenol, 4-nonylphenol (NP), 4-tert-octylphenol, bisphenol A, cholesterol, ethylenediaminetetraacetic acid, and triclosan. The chemicals 4-nonylphenolmonoethoxycarboxylate (NP1EC), 4-nonylphenoldiethoxycarboxylate (NP2EC), and 4-nonylphenoltriethoxycarboxylate (NP3EC) also were detected. Excluding nondetections, the sum of NP1EC through NP3EC concentrations ranged from 5.1 to 260 ug/L among all samples. NP was detected in upstream, effluent, and downstream samples in each stream during at least one time period. NP was detected in 49 percent of environmental samples. Excluding nondetections, concentrations of NP ranged from 100 to 880 nanograms per liter among all samples. NP was also detected in more than one-half of the bed-sediment samples. The most commonly detected wastewater indicator chemicals in samples analyzed by schedule 4433 at the USGS National Water Quality Laboratory were 3,4-dichlorophenyl isocyanate, acetyl-hexamethyl-tetrahydronaphthalene, benzophenone, cholesterol, hexahydrohexamethyl-cyclopenta-benzopyran, N,N-diethyl-meta-toluamide, and

Lee, Kathy E.; Schoenfuss, Heiko L.; Jahns, Nathan D.; Brown, Greg K.; Barber, Larry B.

2008-01-01

328

Effects of acoustic alarms, designed to reduce small cetacean bycatch in gillnet fisheries, on the behaviour of North Sea fish species in a large tank.  

Science.gov (United States)

World-wide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven commercially-available pingers on the behaviour of five North Sea fish species in a large tank were quantified. The species tested were: sea bass (Dicentrarchus labrax), pout (Trisopterus luscus), thicklip mullet (Chelon labrosus), herring (Clupea harengus), and cod (Gadus morhua). The fish were housed as single-species schools of 9-13 individuals in a tank. The behaviour of fish in quiet periods was compared with their behaviour during periods with active pingers. The results varied both between pingers and between fish species. Sea bass decreased their speed in response to one pinger and swam closer to the surface in response to another. Thicklip mullet swam closer to the bottom in response to two pingers and increased their swimming speed in response to one pinger. Herring swam faster in response to one pinger, and pout and cod (close relatives) showed no behavioural responses to any of the pingers. Of the seven pingers tested, four elicited responses in at least one fish species, and three elicited no responses. Whether similar responses would be elicited in these fish species in the wild, and if so, whether such responses would influence the catch rate of fisheries, cannot be derived from the results of this study. However, the results indicate the need for field studies with pingers and fish. Based on the small number of fish species tested, the present study suggests that the higher the frequency of a pinger, the less likely it is to affect the behaviour of marine fish. PMID:17316783

Kastelein, Ronald A; van der Heul, Sander; van der Veen, Jan; Verboom, Willem C; Jennings, Nancy; de Haan, Dick; Reijnders, Peter J H

2007-08-01

329

Status of fish passage facilities at nonfederal hydropower projects  

International Nuclear Information System (INIS)

The status of direct mitigation practices for fish passage was assessed as part of an ongoing, multi-year study of the costs and benefits of environmental mitigation measures at nonfederal hydroelectric power plants. Information was obtained from the Federal Energy Regulatory Commission, hydropower developers and state and federal resource agencies involved in hydropower regulation. Fish ladders were found to be the most common means of passing fish upstream; elevators/lifts were less common, but their use appears to be increasing. A wide variety of mitigative measures, including spill flows, narrow-mesh intake screens, angled bar racks and light- or sound-based guidance measures, is employed to prevent fish from being drawn into turbine intakes. Performance monitoring and detailed, quantifiable performance criteria were frequently lacking. Fifty-two of the 66 projects (82%) with operating downstream fish passage measures had no performance monitoring requirements; 50 of 71 project operators (70%) indicated that no performance objectives had been specified for the mitigative measures. The authors found that comprehensive field studies needed to evaluate the effectiveness of fish passage devices have been rare. 16 refs., 8 figs

330

Tunable Hybridization at Mid Zone and Anomalous Bloch-Zener Oscillations in Optical Waveguide Ladders  

CERN Document Server

We have studied the optical oscillation and tunneling of light waves in optical waveguide ladders formed by two coupled planar optical waveguide arrays. For the band structure, a mid-zone gap is formed due to band hybridization and its wavenumber position can be tuned throughout the whole Brillouin zone, which is different from the Bragg gap. By imposing a gradient in the propagation constant in each array, Bloch-Zener oscillation (BZO) is realized with Zener tunneling between the bands occurring at mid zone, which is contrary to the common BZO with tunneling at the center or edge of the Brillouin zone. The occurrence of BZO is demonstrated by using the field-evolution analysis. The tunable hybridization at mid zone enhances the tunability of BZO in the optical waveguide ladders. This work is of general and fundamental importance in understanding the coherent phenomena in lattice structures.

Zheng, Ming Jie; Yu, Kin Wah

2010-01-01

331

Enhancement of chaotic subdiffusion in disordered ladders with synthetic gauge fields  

Science.gov (United States)

We study spreading wave packets in a disordered nonlinear ladder with broken time-reversal symmetry induced by synthetic gauge fields. The model describes the dynamics of interacting bosons in a disordered and driven optical ladder within a mean-field approximation. The second moment of the wave packet m2=gt? grows subdiffusively with the universal exponent ? ?1/3 similar to the time-reversal case. However, the prefactor g is strongly modified by the field strength and shows a nonmonotonic dependence. For a weak field, the prefactor increases since time-reversal enhanced backscattering is suppressed. For strong fields the spectrum of the linear wave equation reduces the localization length through the formation of gaps and narrow bands. Consequently the prefactor for the subdiffusive spreading law is suppressed.

Yu, Xiaoquan; Flach, Sergej

2014-09-01

332

IPA-CuCl3: a S=1/2 Ladder with Ferromagnetic Rungs  

International Nuclear Information System (INIS)

The spin gap material IPA-CuCl3 has been extensively studied as a ferromagnetic-antiferromagnetic bond-alternating S = 1/2 chain. This description of the system was derived from structural considerations and bulk measurements. New inelastic neutron scattering experiments reveal a totally different picture: IPA-CuCl3 consists of weakly coupled spin ladders with antiferromagnetic legs and ferromagnetic rungs. The ladders run perpendicular to the originally supposed bond-alternating chain direction. The ferromagnetic rungs make this system equivalent to a Haldane S = 1 antiferromagnet. With a gap energy of 1.17(1) meV, a zone-boundary energy of 4.1(1) meV, and almost no magnetic anisotropy, IPA-CuCl3 may be the best Haldane-gap material yet, in terms of suitability for neutron scattering studies in high magnetic fields.

333

IPA-CuCl$_3$: a S=1/2 Ladder with Ferromagnetic Rungs  

CERN Document Server

The spin gap material IPA-CuCl3 has been extensively studied as a ferromagnetic-antiferromagnetic bondalternating S = 1/2 chain. This description of the system was derived from structural considerations and bulk measurements. New inelastic neutron scattering experiments reveal a totally different picture: IPA-CuCl3 consists of weakly coupled spin ladders with antiferromagnetic legs and ferromagnetic rungs. The ladders run perpendicular to the originally supposed bondalternating chain direction. The ferromagnetic rungs make this system equivalent to a Haldane S = 1 antiferromagnet. With a gap energy of 1.17(1) meV, a zone-boundary energy of 4.1(1) meV, and almost no magnetic anisotropy, IPA-CuCl3 may the best Haldane-gap material yet, in terms of suitability for neutron scattering studies in high magnetic fields.

Masuda, T; Manaka, H; Chung, J H

2005-01-01

334

Significance of decay mechanism into continuum in dynamical Wannier-Stark ladder  

Energy Technology Data Exchange (ETDEWEB)

We examine the resonance structure of photodressed electron states of laser-driven Wannier-Stark ladder, namely, dynamic Wannier-Stark ladder, in terms of the excess density of states (DOS) closely related to a lifetime of the state of concern. It is revealed that the resonance structure in the strong laser-field region shows clear dependence on the ratio, ?, of a Bloch-frequency to a laser frequency. As the laser strength increases, for ? = 1, the excess DOS becomes involved with a lot of newly-growing resonance peaks. This result would be understood from the viewpoint of a Fano-like decay-mechanism caused by a multichannel continuum effect, in marked contrast to the cases of larger ?’s; for ? = 3, the excess DOS just is found to show a pronounced red-shift of a single dominant peak caused by a single-channel continuum effect.

Nemoto, Yuya [Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573 (Japan); Maeshima, Nobuya; Hino, Ken-ichi [Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8573, Japan and Center for computational Sciences, University of Tsukuba, Tsukuba 305-8577 (Japan)

2013-12-04

335

Non-perturbative effective field theory for two-leg antiferromagnetic spin ladders  

CERN Document Server

We study the long wavelength limit of a spin 1/2 Heisenberg antiferromagnetic two-leg ladder, treating the interchain coupling in a non-perturbative way. We perform a mean field analysis and then include exactly the fluctuations. This allows for a discussion of the phase diagram of the system and provides an effective field theory for the low energy excitations. The coset fermionic Lagrangian obtained corresponds to a perturbed SU(4)_1/U(1) Conformal Field Theory (CFT). This effective theory is naturally embedded in a SU(2)_2 x Z_2 CFT, where perturbations are easily identified in terms of conformal operators in the two sectors. Crossed and zig-zag ladders are also discussed using the same approach.

Cabra, D C; Rossini, G L

2001-01-01

336

A New Numerical Approach Toward MPS State on Spin Ladder Systems  

Science.gov (United States)

The matrix product state (MPS) representation used by DMRG is extremely effective in 1D, but loses effectiveness exponentially with the width in ladder systems. Tensor product wavefunction, such as PEPS, are efficient representations of 2D states but calculations utilizing them are very inefficient. As an intermediate approach between these, we consider a wavefunction consisting of an MPS multiplied by local bond exponentials ^-?Hbond applied on adjacent sites in the lattice which appear distant in the MPS. The exponentials restore the area law to the MPS. For efficient calculation, the bond-exponentials are transferred to the Hamiltonian in a matrix product operator representation, acting as a similarity transformation, preserving the eigenvalues. For this method to be successful, not only should the modified MPS representation be efficient, the MPO representation of the transformed Hamiltonian should have a small matrix dimension. We report on preliminary results on ladders with several legs for this approach.

Zhu, Zhenyue; White, Steven

2010-03-01

337

Significance of decay mechanism into continuum in dynamical Wannier-Stark ladder  

International Nuclear Information System (INIS)

We examine the resonance structure of photodressed electron states of laser-driven Wannier-Stark ladder, namely, dynamic Wannier-Stark ladder, in terms of the excess density of states (DOS) closely related to a lifetime of the state of concern. It is revealed that the resonance structure in the strong laser-field region shows clear dependence on the ratio, ?, of a Bloch-frequency to a laser frequency. As the laser strength increases, for ? = 1, the excess DOS becomes involved with a lot of newly-growing resonance peaks. This result would be understood from the viewpoint of a Fano-like decay-mechanism caused by a multichannel continuum effect, in marked contrast to the cases of larger ?’s; for ? = 3, the excess DOS just is found to show a pronounced red-shift of a single dominant peak caused by a single-channel continuum effect

338

Antiferromagnetic model and magnetization plateaus on the zigzag ladder with two- and three-site exchanges  

International Nuclear Information System (INIS)

The Ising approximation is proposed for the Heisenberg model with two- and three-spin exchange interactions on a zigzag ladder placed in a strong magnetic field. Using the transfer matrix technique the magnetization is calculated and compared with the results obtained in the dynamical recursive approach. Magnetization plateaus are found at m=0 and m=1/3 with the two- and three-spin exchanges. The magnetic susceptibility in small and large zigzag ladders for various exchange parameters and temperatures is also analyzed. As temperature decreases the magnetic susceptibility versus magnetic field shows the formation of spin pseudogaps and transformation from double to four peak structure. Small clusters also exhibit characteristic features of large thermodynamic systems

339

Antiferromagnetic model and magnetization plateaus on the zigzag ladder with two- and three-site exchanges  

Energy Technology Data Exchange (ETDEWEB)

The Ising approximation is proposed for the Heisenberg model with two- and three-spin exchange interactions on a zigzag ladder placed in a strong magnetic field. Using the transfer matrix technique the magnetization is calculated and compared with the results obtained in the dynamical recursive approach. Magnetization plateaus are found at m=0 and m=1/3 with the two- and three-spin exchanges. The magnetic susceptibility in small and large zigzag ladders for various exchange parameters and temperatures is also analyzed. As temperature decreases the magnetic susceptibility versus magnetic field shows the formation of spin pseudogaps and transformation from double to four peak structure. Small clusters also exhibit characteristic features of large thermodynamic systems.

Hovhannisyan, V.V. [Department of Theoretical Physics, Yerevan Physics Institute, Alikhanian Brothers 2, 375036 Yerevan (Armenia)], E-mail: vahmer@rambler.ru; Ananikian, N.S. [Department of Theoretical Physics, Yerevan Physics Institute, Alikhanian Brothers 2, 375036 Yerevan (Armenia)

2008-05-05

340

Three-Leg Antiferromagnetic Heisenberg Ladder with Frustrated Boundary Condition Ground State Properties  

CERN Document Server

The antiferromagnetic Heisenberg spin systems on the three-leg ladder are investigated. Periodic boundary condition is imposed in the rung direction. The system has an excitation gap for all antiferromagnetic inter-chain coupling ($J_{\\perp}>0$). The estimated gap for the strong coupling limit ($J_{\\perp}/J_1 \\to \\infty$) is 0.28$J_1$. Although the interaction is homogeneous and only nearest-neighbor, the ground states of the system are dimerized and break the translational symmetry in the thermodynamic limit. Introducing the next-nearest neighbor coupling ($J_2$), we can see that the system is solved exactly. The ground state wave function is completely dimer-ordered. Using density matrix renomalization group algorithm, we show numerically that the original model ($J_2=0$) has the same nature with the exactly solvable model. The ground state properties of the ladder with a higher odd number of legs are also discussed.

Kawano, K; Kawano, Kenro; Takahashi, Minoru

1997-01-01

 
 
 
 
341

Electronic States and Excitation Spectra of Copper Oxides with Ladder and/or Chain  

CERN Document Server

Recently the superconductivity has been reported in the copper oxides (Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$ with ladders and edge-sharing chains under pressure. In order to understand the mechanism of the superconductivity, it is crucial to clarify the distribution of self-doped holes. From the analysis of the optical conductivity by ionic model and exact diagonalization method, we confirm that with substituting Ca for Sr, the self-doped holes are transferred from the chains to the ladders. We also examine the electronic states of edge-sharing chain in a variety of copper oxides, and derive the effective Hamiltonian. The dependences of the magnetic interactions between Cu ions and of the hopping energies of the Zhang-Rice singlet on the bond angle of Cu-O-Cu are discussed.

Mizuno, Y; Maekawa, S; Mizuno, Yoshiaki; Tohyama, Takami; Maekawa, Sadamichi

1998-01-01

342

Minibands and Wannier-Stark ladders in semiconductor superlattices studied by infrared spectroscopy  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english We review the basic features of interminiband absorption in superlattices, focussing on the joint density of states, the oscillator strength and the associated sum rule. Then we will discuss infrared spectroscopic studies under application of an electric field. With a field in the plane of the layer [...] s, a hot-electron distribution can be generated. Using the temperature dependence of the interminiband absorption, energy loss and relaxation rates can be determined. A vertical electric field leads to negative differential resistance, domain formation and the break-up of the minibands into Wannier- Stark ladders. We will present experiments showing the formation of interpenetrating Wannier- Stark ladders in the continuum, which are strongly coupled by Zener resonances. This is the first time to correlate transport and infrared absorption in a biased superlattice.

M., Helm; W., Hilber; G., Strasser; R., DeMeester; F. M., Peeters.

1999-12-01

343

Asymptotic behavior of the proton electromagnetic form factor with pion exchanges in the ladder approximation  

International Nuclear Information System (INIS)

The asymptotic behavior of the proton electromagnetic form factor due to virtual pion exchanges is studied by restricting to a class of ladder diagrams. We set up an off-mass-shell integral equation for the modified proton-proton-photon vertex due to virtual pion exchanges by summing up an infinite number of ladder diagrams. This integral equation is converted into a set of coupled differential equations involving Lorentz-invariant amplitudes. From the solutions of the differential equations it is found that the usual form factor is modified by a factor exp][-1/2 +- (1/2)(1-g2/?2)/sup 1/2/]lnt] at large momentum transfers, where g is the pion-nucleon coupling constant

344

Electromagnetically induced transparency in ladder-type inhomogeneously broadened media: Theory and experiment  

International Nuclear Information System (INIS)

We develop a theory of electromagnetically induced transparency in a three-level, ladder-type Doppler-broadened medium, paying special attention to the case where the coupling and probe beams are counterpropagating and have similar frequencies, so as to reduce the total Doppler width of the two-photon process. The theory is easily generalized to deal with the ? configuration, where the ideal arrangement involves two copropagating beams. We discuss different possible regimes, depending on the relative importance of the various broadening mechanisms, and identify ways to optimize the absorption-reduction effect. The theory is compared to the results of a recent experiment (on a ladder-type system), using the Rb D2 line, with generally very good agreement. The maximum absorption reduction observed (64.4%) appears to be mostly limited by the relatively large (?5 MHz) linewidth of the diode lasers used in our experiment

345

Staggered-ladder quasienergy spectra for generic quasimomentum and quantum-dynamical manifestations  

Science.gov (United States)

A non-Poisson regular quasienergy spectrum is found for the generalized kicked particle under quantum-resonance conditions at generic quasimomentum, a quantity most relevant in atom-optics experimental realizations of kicked-rotor systems. The regular spectrum has the structure of a staggered ladder, i.e., it is the superposition of a finite number of ladder subspectra all having the same spacing, which is independent of the nonintegrability of the system. This spectral structure is shown to have distinct quantum-dynamical manifestations: a suppression of quantum resonances and a dynamical localization characterized by unique features such as traveling-wave components in the time evolution. These phenomena are found to be robust under small variations of the quasimomentum and should therefore be experimentally observable using Bose-Einstein condensates with sufficiently small quasimomentum width.

Dana, Itzhack

2013-04-01

346

Telecast of Astronaut Neil Armstrong descending ladder to surface of the moon  

Science.gov (United States)

Astronaut Neil A. Armstrong, Apollo 11 commander, descends the ladder of the Apollo 11 Lunar Module prior to making the first step by man on the moon. This view is a black and white reproduction taken from a telecast by the Apollo 11 lunar surface camera during extravehicular activity. The black bar running through the center of the picture is an anamoly in the television ground data system at the Goldstone Tracking Station.

1969-01-01

347

Unexpectedly low mitochondrial DNA variation within the ladder snake Rhinechis scalaris  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The Iberian Peninsula, as an important glacial refugia for much fauna and flora, is a well known biodiversity hotspot. Of the studied herpetofauna almost all species that are not recent colonizers of the area show extensive intraspecific genetic variation, often at a level that has implied cryptic speciation. In this study variation within the ladder snake, Rhinechis scalaris, essentially an Iberian endemic, was examined using cytochrome b mitochondrial DNA sequences. Surprisingly no variati...

James Harris, D.; Carretero, Miguel A.; Biaggini, Marta; Nulchis, Valeria

2008-01-01

348

Large Spin Formation and Thermodynamic Properties of Disordered Spin Ladders with Site Dilution  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Low temperature properties of antiferromagnetic two-leg spin-1/2 ladders with bond randomness and site dilution (or doping with nonmagnetic impurities) are studied using the real-space renormalization-group technique. We find that for non zero doping concentrations the systems are driven into a phase dominated by large effective spins, i.e. the Large Spin phase. The susceptibility follows a universal Curie-like 1/T behavior at low temperature,regardless of the doping concent...

Yusuf, Eddy; Yang, Kun

2002-01-01

349

Three-ladder vertex in the Reggeon graph technique in QCD  

International Nuclear Information System (INIS)

Using perturbative QCD a Reggeon graph technique is formulated for calculating the asymptotic behavior of the amplitudes of deep-inelastic processes at high energies. The three-ladder (three-Pomeron) vertex G is calculated. It turns out that in QCD the vertex G does not become zero for the momenta transferred to the Pomerons Q/sub t/?0. It is shown that the usual AGK rules are valid for the cutting of Reggeons in QCD

350

Analysis of an integral equation for causal distributions in the ladder PHI63 theory  

International Nuclear Information System (INIS)

Using the integral equation for a spectral function, the behaviour of the spectral function of the Deser-Gilbert-Sudarshan representation for matrix elements of the current commutator in the ladder approximation for the PHI63 field theory is studied. The integral equation for a spectral function is formulated and solved. The solution for the spectral function does not satisfy the necessary condition of automodelity. The current commutator behaviour near the light cone is derived

351

Comment on ``Anomalous Thermal Conductivity of Frustrated Heisenberg Spin Chains and Ladders''  

CERN Document Server

In a recent letter [Phys. Rev. Lett. 89, 156603 (2002); cond-mat/0201300], Alvarez and Gros have numerically analyzed the Drude weight for thermal transport in spin ladders and frustrated chains of up to 14 sites and have proposed that it remains finite in the thermodynamic limit. In this comment, we argue that this conclusion cannot be sustained if the finite-size analysis is taken to larger system sizes.

Heidrich-Meisner, F; Cabra, D C; Brenig, W

2003-01-01

352

Gain-assisted sub- and super-luminal in a ladder atomic system  

Energy Technology Data Exchange (ETDEWEB)

With the occurrence of an incoherent pumping field, the properties of the dispersion and the absorption of a three-level ladder-type system are changed greatly. With proper parameters, the system can produce normal and anomalous dispersion regions in the gain region. The existence of the incoherent pumping is the cause for these phenomena, and it can be a knob to manipulate the group velocity of a weak probe field from sub-luminal to super-luminal.

Zeng Yaguang [Physics Department, Foshan University, Foshan 528000 (China); Han, Dingan, E-mail: handingan@yahoo.com.c [Physics Department, Foshan University, Foshan 528000 (China); Bai Yanfeng [Department of Physics, Southeast University, Nanjing 210096 (China); Chen Weicheng; Cao Hui; Lu Hong [Physics Department, Foshan University, Foshan 528000 (China)

2009-09-21

353

Defect Motion and Lattice Pinning Barrier in Josephson-Junction Ladders  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study motion of domain wall defects in a fully frustrated Josephson-unction ladder system, driven by small applied currents. For small system sizes, the energy barrier E_B to the defect motion is computed analytically via symmetry and topological considerations. More generally, we perform numerical simulations directly on the equations of motion, based on the resistively-shunted junction model, to study the dynamics of defects, varying the system size. Coherent motion of ...

Kang, H.; Lim, Jong Soo; Fortin, J. -y; Choi, J.; Choi, M. Y.

2005-01-01

354

Chirping a two-photon transition in a multi-state ladder  

CERN Document Server

We consider a two-photon transition in a specific ladder system driven by a chirped laser pulse. In the weak field limit, we find that the excited state probability amplitude arises due to interference of multiple quantum paths which are weighted by quadratic phase factors. The excited state population has the form of a Gauss sum which plays a prominent role in number theory.

Merkel, W; Schleich, W P; Lutz, E; Paulus, G G; Girard, B; Merkel, Wolfgang; Mack, Holger; Schleich, Wolfgang P.; Lutz, Eric; Paulus, Gerhard G.; Girard, Bertrand

2007-01-01

355

Beyond Rainbow-Ladder in a covariant three-body Bethe-Salpeter approach: Baryons  

CERN Document Server

We report on recent results of a calculation of the nucleon and delta masses in a covariant bound-state approach, where to the simple rainbow-ladder gluon-exchange interaction kernel we add a pion-exchange contribution to account for pion cloud effects. We observe good agreement with lattice data at large pion masses. At the physical point our masses are too large by about five percent, signaling the need for more structure in the gluon part of the interaction.

Sanchis-Alepuz, Hèlios; Fischer, Christian S

2014-01-01

356

Integrable models and quantum spin ladders: comparison between theory and experiment for the strong coupling compounds  

CERN Document Server

(abbreviated) This article considers the integrable spin ladder models and their application to the physics of real compounds. The ground state properties of the integrable two-leg spin-1/2 and the mixed spin-(1/2,1) ladder models at zero temperature are analyzed by means of the Thermodynamic Bethe Ansatz. Solving the TBA equations yields exact results for the critical fields and critical behaviour. The thermal and magnetic properties of the models are investigated in terms of the recently introduced High Temperature Expansion method, which is discussed in detail. It is shown that in the strong coupling limit the integrable spin-1/2 ladder model exhibits three quantum phases: (i) a gapped phase in the regime $HH_{c2}$, and (iii) a Luttinger liquid magnetic phase in the regime $H_{c1}

Batchelor, M T; Oelkers, N; Tsuboi, Z

2005-01-01

357

Orbital currents and charge density oscillations in a generalized Hubbard ladder  

CERN Document Server

We study a generalized Hubbard model on the two-leg ladder at zero temperature, focusing on a parameter region with staggered flux (SF)/d-density wave (DDW) order. Using bosonization and a perturbative renormalization-group (RG) approach, we investigate the location of a SF/DDW phase with true long-range order in the phase diagram of the weakly interacting half-filled ladder. Finite-system density-matrix renormalization-group (DMRG) calculations are used to study ladders with up to 200 rungs, for hole doping delta and intermediate-strength interactions. In the doped SF/DDW phase, the staggered rung current and the rung electron density both show periodic spatial oscillations, with characteristic wavelengths 2/delta and 1/delta, respectively, corresponding to ordering wavevectors 2k_F and 4k_F for the currents and densities, where 2k_F = pi(1-delta). The density minima are located at the anti-phase domain walls of the staggered current. For sufficiently large dopings, SF/DDW order is suppressed. The rung densi...

Fjaerestad, J O; Schollwöck, U

2004-01-01

358

Entanglement spectra between coupled Tomonaga-Luttinger liquids: Applications to ladder systems and topological phases  

Science.gov (United States)

We study the entanglement spectrum (ES) and entropy between two coupled Tomonaga-Luttinger liquids (TLLs) on parallel periodic chains. This problem gives access to the entanglement properties of various interesting systems, such as spin ladders as well as two-dimensional topological phases. By expanding interchain interactions to quadratic order in bosonic fields, we are able to calculate the ES for both gapped and gapless systems using only methods for free theories. In certain gapless phases of coupled nonchiral TLLs, we interestingly find an ES with a dispersion relation proportional to the square root of the subsystem momentum, which we relate to a long-range interaction in the entanglement Hamiltonian. We numerically demonstrate the emergence of this unusual dispersion in a model of hard-core bosons on a ladder. In gapped phases of coupled nonchiral TLLs, which are relevant to spin ladders and topological insulators, we show that the ES consists of linearly dispersing modes, which resembles the spectrum of a single-chain TLL but is characterized by a modified TLL parameter. Based on a calculation for coupled chiral TLLs, we are also able to provide a very simple proof for the correspondence between the ES and the edge-state spectrum in quantum Hall systems consistent with previous numerical and analytical studies.

Lundgren, Rex; Fuji, Yohei; Furukawa, Shunsuke; Oshikawa, Masaki

2013-12-01

359

Zero Modes and Thermodynamics of Disordered Spin-1/2 Ladders  

CERN Document Server

The influence of nonmagnetic doping on the thermodynamic properties of two-leg S = 1/2 spin ladders is studied in this paper. It is shown that, for a weak interchain coupling, the problem can be mapped onto a model of random mass Dirac (Majorana) fermions. We investigate in detail the structure of the fermionic states localized at an individual mass kink (zero modes) in the framework of a generalized Dirac model. The low-temperature thermodynamic properties are dominated by these zero modes. We use the single-fermion density of states, known to exhibit the Dyson singularity in the zero-energy limit, to construct the thermodynamics of the spin ladder. In particular, we find that the magnetic susceptibility $\\chi$ diverges at $T\\to 0$ as $1/T\\ln^2(1/T)$, and the specific heat behaves as $C\\propto 1/\\ln^3(1/T)$. The predictions on magnetic susceptibility are consistent with the most recent results of quantum Monte Carlo simulations on doped ladders with randomly distributed impurities. We also calculate the aver...

Gogolin, A O; Tsvelik, A M; Yu, L; Gogolin, Alexander O.; Nersesyan, Alexander A.; Tsvelik, Alexei M.

1999-01-01

360

Ladders with two, three and four coupled Ising spin chains. Magnetic properties  

International Nuclear Information System (INIS)

We consider ladders with two, three and four coupled Ising spin chains, characterized by interchain and intrachain couplings, to study their magnetic behaviour for different ratios of interaction constants and different values of magnetic field, by using a transfer matrix method and a complex algorithm realizing the diagonalization and the differentiation. It is interesting that when the competition between interchain and intrachain interactions is different from zero the magnetization goes from the value one to the value zero in a narrow interval of nonzero temperatures, where, also, the susceptibility exhibits a very high peak. This narrow interval, increasing the number of chains, is displaced towards the higher temperatures. Also, in the case of interchain antiferromagnetic couplings, it becomes clear the formation of interchain spin pairs. The spin -1/2 ladder or the system of coupled spin chains may be realized in nature by vanadyl pyrophosphate ((VO)2P2O7) or similar materials. All these intermediate systems are today important to gain further insights into the physics of one-dimensional spin chains and the two-dimensional high-Tc spin systems, both of which have shown interesting and unusual magnetic and superconducting properties. It is plausible that experimental and theoretical studies of ladders may lead to other interesting physical phenomena. (author). 22 refs, 6 figs

 
 
 
 
361

Quantum transport in ladder-type networks: the role of nonlinearity, topology and spin  

International Nuclear Information System (INIS)

We investigate the quantum transport of electrons, phase solitons, etc, through the mesoscopic networks of zero-dimensional quantum dots. Straight and circular ladders are chosen as networks with each coupled with three semi-infinite leads (with one incoming and the other two outgoing). Two transmission probabilities as functions of the incident energy ? show a transition from anti-phase aperiodic to degenerate periodic spectra at the critical energy ?c which is determined by a bifurcation point of the bulk energy dispersions. TPs of the circular ladder depend only on the parity of the winding number. The introduction of a single missing bond (MB) or missing step doubles the period of the periodic spectra at ? > ?c. Shift of the MB by a lattice constant results in a striking switching effect at ? c. In the presence of the electric-field-induced spin-orbit interaction (SOI), an obvious spin filtering occurs for the spin-unpolarized injection. For the spin-polarized injection, on the other hand, the spin transport shows spin-flip (magnetization reversal) oscillations with respect to SOI. We also show a role of soliton in the context of its transport through the ladder networks.

362

Bond-impurity induced bound states in disordered spin-1/2 ladders  

CERN Document Server

We discuss the effect of weak bond-disorder in two-leg spin ladders on the dispersion relation of the elementary triplet excitations with a particular focus on the appearance of bound states in the spin gap. Both the cases of modified exchange couplings on the rungs and the legs of the ladder are analyzed. Based on a projection on the single-triplet subspace, the single-impurity and small cluster problems are treated analytically in the strong-coupling limit. Numerically, we study the problem of a single impurity in a spin ladder by exact diagonalization to obtain the low-lying excitations. At finite concentrations and to leading order in the inter-rung coupling, we compare the spectra obtained from numerical diagonalization of large systems within the single-triplet subspace with the results of diagrammatic techniques, namely low-concentration and coherent-potential approximations. The contribution of small impurity clusters to the density of states is also discussed.

Arlego, M; Cabra, D C; Heidrich-Meisner, F; Honecker, A; Rossini, G

2004-01-01

363

DISEÑO DE UNA HERRAMIENTA DE EVALUACIÓN DEL DESEMPEÑO AMBIENTAL EN LAS GRANJAS PISCÍCOLAS / DESIGNING AN ASSESMENT TOOL OF ENVIROMENTAL PERFORMANCE INTO FISHING FARMS  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Con el objetivo de evaluar el desempeño ambiental de las empresas piscícolas, se diseñó y aplicó una herramienta basada en las listas de chequeo la cuál fue elaborada a partir de las recomendaciones dadas por la FAO en su código de conducta para una acuicultura responsable, en las guías de organizac [...] iones no gubernamentales que buscan el desarrollo de una acuicultura responsable y de modificaciones a las propuestas metodológicas de Vinatea (1999) y Leripio (2003). La aplicación por entrevista del cuestionario, acompañada de inspección ocular, permitió la recolección de valiosa información que calificó la actuación de las empresas piscícolas como crítica, pésima, aceptable, buena y excelente sostenibilidad. La información entregada a los planificadores del municipio en cuestión se convirtió en una guía para sus acciones a través de metas, estrategias y responsables a corto, mediano y largo plazo. Se comprobó que los aspectos negativos al desempeño ambiental son en su mayoría de rápida y económica solución, y que se requiere de trabajo proactivo entre municipio, corporación ambiental regional y productores. Se recomienda la aplicación de la herramienta en cuatro fases: evaluación preliminar, sensibilización y concienciación, autoevaluación y suministro de guías y recomendaciones para el buen desempeño ambiental. Abstract in english With the objective of evaluating the environmental performance of the fish farms facilities, it was designed and it applied a tool based on the check lists, which was elaborated of agreement with the recommendations given by the FAO in their Conduct Code for a Responsible Aquaculture, in the guides [...] of non government organizations (NGOs) that look for the development of a responsible aquaculture and of modifications to the methodological proposals of Vinatea (1999) and Leripio (2003). The application for interview of the questionnaire, accompanied by ocular inspection, allowed the gathering of valuable information that qualified the performance of the fish farms facilities like critic, terrible, acceptable, good and excellent sustainability. The report of results given to the municipal government became a guide for its actions through goals, strategies and responsible entities. It was certain that the negative aspects to the environmental acting are in their majority of quick and economic solution, and that it is required of work proactive among the municipal government, the regional environmental corporation and the producers. The application of the tool is recommended in four phases: preliminary evaluation, sensitization and understanding, autoevaluation and supply of guides and recommendations for the good environmental acting.

Sandra, Pardo; Héctor, Suárez; Paulo, Jardim-Manso; Eduardo, Soriano-Sierra.

364

DISEÑO DE UNA HERRAMIENTA DE EVALUACIÓN DEL DESEMPEÑO AMBIENTAL EN LAS GRANJAS PISCÍCOLAS / DESIGNING AN ASSESMENT TOOL OF ENVIROMENTAL PERFORMANCE INTO FISHING FARMS  

Scientific Electronic Library Online (English)

Full Text Available SciELO Colombia | Language: Spanish Abstract in spanish Con el objetivo de evaluar el desempeño ambiental de las empresas piscícolas, se diseñó y aplicó una herramienta basada en las listas de chequeo la cuál fue elaborada a partir de las recomendaciones dadas por la FAO en su código de conducta para una acuicultura responsable, en las guías de organizac [...] iones no gubernamentales que buscan el desarrollo de una acuicultura responsable y de modificaciones a las propuestas metodológicas de Vinatea (1999) y Leripio (2003). La aplicación por entrevista del cuestionario, acompañada de inspección ocular, permitió la recolección de valiosa información que calificó la actuación de las empresas piscícolas como crítica, pésima, aceptable, buena y excelente sostenibilidad. La información entregada a los planificadores del municipio en cuestión se convirtió en una guía para sus acciones a través de metas, estrategias y responsables a corto, mediano y largo plazo. Se comprobó que los aspectos negativos al desempeño ambiental son en su mayoría de rápida y económica solución, y que se requiere de trabajo proactivo entre municipio, corporación ambiental regional y productores. Se recomienda la aplicación de la herramienta en cuatro fases: evaluación preliminar, sensibilización y concienciación, autoevaluación y suministro de guías y recomendaciones para el buen desempeño ambiental. Abstract in english With the objective of evaluating the environmental performance of the fish farms facilities, it was designed and it applied a tool based on the check lists, which was elaborated of agreement with the recommendations given by the FAO in their Conduct Code for a Responsible Aquaculture, in the guides [...] of non government organizations (NGOs) that look for the development of a responsible aquaculture and of modifications to the methodological proposals of Vinatea (1999) and Leripio (2003). The application for interview of the questionnaire, accompanied by ocular inspection, allowed the gathering of valuable information that qualified the performance of the fish farms facilities like critic, terrible, acceptable, good and excellent sustainability. The report of results given to the municipal government became a guide for its actions through goals, strategies and responsible entities. It was certain that the negative aspects to the environmental acting are in their majority of quick and economic solution, and that it is required of work proactive among the municipal government, the regional environmental corporation and the producers. The application of the tool is recommended in four phases: preliminary evaluation, sensitization and understanding, autoevaluation and supply of guides and recommendations for the good environmental acting.

Sandra, Pardo; Héctor, Suárez; Paulo, Jardim-Manso; Eduardo, Soriano-Sierra.

2005-07-01

365

Development of DNA vaccines for fish : Vector design, intramuscular injection and antigen expression using viral haemorrhagic septicaemia virus genes as model  

DEFF Research Database (Denmark)

Disease control is one of the major concerns in the aquaculture industry. However, there are no vaccines available for the prevention of many piscine infectious diseases, especially those of viral and parasitic origin. DNA-based vaccination could circumvent several problems associated with traditional methods of immunization, but little is known on its efficacy in fish. The luciferase and lacZ reporter genes were used to characterize expression of plasmid-encoded genes in rainbow trout and zebra fish injected intramuscularly. For a given dose of DNA, the luciferase activity was higher in fish than in mouse muscle. The enzyme activity in fish peaked with 1 ?g of DNA and remained constant for over 12 weeks, but it was not limited to the injected muscle since luciferase activity was also detected in the gills. Thin sections of rainbow trout muscle injected with the lacZ reporter gene showed no permanent tissue damage. To further investigate the ability of DNA-based vaccines to induce protective immunity in fish,viral haemorrhagic septicaemia virus G and N genes were cloned individually into an expression plasmid. Both G and N proteins produced in transfected fish cells appeared identical to native viral proteins, as they were recognized by specific monoclonal antibodies. Coinjection of the G and luciferase genes in fish muscle resulted in a rapid decrease of the luciferase activity over time, when compared to the control, suggesting that fish raised a cellular immune response to the G protein, killing the transfected host cells and ablating further expression of G protein and luciferase. Finally, young rainbow trout injected with the G construct, alone or together with the N construct, were strongly protected against challenge with live virus. These results suggest that DNA vaccines should be as successful for fish as they are for other animals.

Heppell, Joël; Lorenzen, Niels

1998-01-01

366

Fish barriers  

International Nuclear Information System (INIS)

Experiments to test the avoidance reactions to sound was also performed. The evaluation of these results where however complicated by the fact that the fishes swam rapidly to and fro in the experimental chamber and thus by pure chance very frequently were close to the sound generator

367

Effects of acoustic alarms, designed to reduce small cetacean bycatch in gillnet fisheries, on the behaviour of North Sea fish species in a large tank  

Digital Repository Infrastructure Vision for European Research (DRIVER)

World-wide many cetaceans drown incidentally in fishing nets. To reduce the unwanted bycatch in gillnets, pingers (acoustic alarms) have been developed that are attached to the nets. In the European Union, pingers will be made compulsory in some areas in 2005 and in others in 2007. However, pingers may effect non-target marine fauna such as fish. Therefore in this study, the effects of seven commercially-available pingers on the behaviour of five North Sea fish species in a large tank were qu...

Kastelein, R. A.; Heul, S.; Veen, J.; Verboom, W. C.; Jennings, N.; Haan, D.; Reijnders, P. J. H.

2007-01-01

368

Fish irradiation  

International Nuclear Information System (INIS)

Chub-mackerel was chosen for the study because they are the most common fish in Thailand. Preliminary investigations were conducted to determine the maximum radiation dose of gamma-rays by organoleptic tests. The samples were subjected to radiation at various doses up to 4 Mrad. Many experiments were conducted using other kinds of fish. The results showed that 1 Mrad would be the maximum acceptable dose for fish. Later, the influence of the radiation dose from 0.1-1 Mrad was studied in order to find the optimum acceptable dose for preservation of fish without off-flavour. For this purpose, the Hedonic scale was used. It was found that 0.2 and 0.5 Mrad gave the best result on Chub mackerel. The determinations of optimum dose, organoleptic, microbiological and trimethylamine content changes were done. The results showed that Chub mackerel irradiated at 0.2, 0.5 and 1 Mrad stored at 30C for 71 days were still acceptable, on the contrary the untreated samples were found unacceptable at 14 days. The trimethylamine increment was significantly higher in the untreated samples. At 15 days storage, trimethylamine in the non-irradiated Chub-mackerel was about 10 times higher than the irradiated ones. At 51 and 79 days storage, about 13 times higher in the control samples than the irradiated samples except 0.1 Mrad. Only 2 times higher was found for the 0.1 Mrad. The microbiological results showed that the irradiation above 0.2 Mrad gave favorable extension of shelf-life of fish

369

D0 Silicon Upgrade: Thermally Induced Stresses in the Components of a D0 Ladder in the Silicon Tracker  

International Nuclear Information System (INIS)

During the operation of the silicon tracker, the ladders will be in direct thermal contact with a cooling channel. The expected operating temperature of the cooling channel is 0 C, maintained by a cooling fluid whose bulk temperature is below 0 C. The assembly temperature is assumed to be 22 C. Due to the mis-match of material expansion coefficients, thermal stresses will be induced in the epoxy, beryllium, and silicon of the ladders. Calculations are presented here as well as some thermal cycling results on test samples. Shown in Figures 1 and 2 are perspective views of the top and bottom of a 3 chip ladder. The silicon temperature within the ladders will not be uniform due to the relative location of the heat dissipating components and the cooling channel. As an example the following plot demonstrates the expected temperature distribution in the 3 chip single sided ladder during operation. Under expected operating conditions of 0.75 W hybrid component power dissipation and 0.5 W per SVX II chip, the temperature profile is shown for two situations of how the ladder is constructed. The cooling channel corresponds roughly to locations on the silicon between 32 and 42 mm. The silicon in this region is sandwiched between two plates of beryllium and is about 4 C. For a construction temperature of 22 C the beryllium/silicon/beryllium assembly will see a 18 C change in temperature. To be conservative a 20 C temperature change will be assumed (some larger temperature extremes will be considered) within the ladder.

370

36 CFR 2.3 - Fishing.  

Science.gov (United States)

...by Federal statutory law. (5) Fishing by the use of drugs, poisons, explosives, or electricity. (6) Digging...200 feet of a public raft or float designated for water sports, or within the limits of locations designated as...

2010-07-01

371

Dynamic (Vibrational and Static Structural Analysis of Ladder Frame  

Directory of Open Access Journals (Sweden)

Full Text Available Automotive chassis is the back bone of an automobile, which acts as the frame to support the body and other different parts of the vehicle. It is the most crucial element that gives strength and stability to the vehicle under different conditions. So the frame should be extremely rigid and strong so that it can withstand shocks, twists, stresses and vibrations to which it is subjected while vehicle is moving on road. Thus strength and stiffness are the two important design considerations. In this paper static structural analysis and model analysis of a Tata 407 truck chassis is done. Since it is easy to analyse structural systems by finite element method, the chassis is modelled using CATIA and the finite element analysis is done using the ANSYS workbench.

Ketan Gajanan Nalawade

2014-05-01

372

Genetic diversity of Salminus brasiliensis (Characiformes: Characidae) collected in the passage ladder of the Canoas I hydropower plant in the Paranapanema River, Brazil
Diversidade genética de Salminus brasiliensis (Characiformes: Characidae) coletados na escada de transposição da Hidrelétrica de Canoas I, rio Paranapanema, Brasil
 

Digital Repository Infrastructure Vision for European Research (DRIVER)

The aim of this study was to evaluate the genetic diversity of Salminus brasiliensis collected three times in the passage ladder of the hydropower plant Canoas I, in the Paranapanema River (Brazil). Fish samples were collected on 14 (CI14), 18 (CI18) and 25 (CI25) February 2008. Eight primers using RAPD technique were evaluated. Seventy-nine in 105 fragments amplified using these primers were polymorphic fragments (75.2%), 32 had frequencies with significant differences (P<0.05), 10 had low f...

Patricia Cristina Gomes; Nelson Mauricio Lopera-Barrero; Lauro Vargas; Danilo Pedro Streit Junior; Jayme Aparecido Povh; Rodolfo Nardez Sirol; Ricardo Pereira Ribeiro

2013-01-01

373

Role of inter-ladder coupling in LiV$_{2}$O$_{5}$ and NaV$_{2}$O$_{5}$  

CERN Document Server

We calculate the optical conductivity of LiV$_{2}$O$_{5}$ and NaV$_{2}$O$_{5}$ using the standard Lanczos algorithm. It is shown that a quarter-filled extended Hubbard model on a system of coupled ladders provides a quantitative explanation for the highly anisotropic optical conductivity of these two vanadium oxides. In particular, the complete suppression of low-energy peaks in the spectrum of LiV$_{2}$O$_{5}$ with electrical field parallel to the leg direction has to be attributed both to the double chain charge ordering pattern and to the strong inter-ladder hopping. Furthermore, it is found that the main differences between the optical properties of LiV$_{2}$O$_{5}$ and NaV$_{2}$O$_{5}$ are due to the completely different nature of the inter-ladder coupling: In contrast to LiV$_{2}$O$_{5}$, in NaV$_{2}$O$_{5}$ neighboring ladders are coupled by a strong Coulomb repulsion, and not by inter-ladder hopping.

Huebsch, A; Becker, K W

2001-01-01

374

Synthesis, structure, and magnetic properties of an antiferromagnetic spin-ladder complex: bis(2,3-dimethylpyridinium) tetrabromocuprate.  

Science.gov (United States)

The complex (2,3-dmpyH)2CuBr4 has been synthesized and its crystal packing determined by single-crystal X-ray diffraction (2,3-dmpyH = 2,3-dimethylpyridinium). The compound crystallizes in the triclinic space group P1. The crystal packing is characterized by the formation of a ladder structure for the CuBr4 anions showing short Br...Br contacts. The rungs of the ladder are formed via a crystallographic inversion center, while the rails are formed via unit cell translations. Variable temperature magnetic susceptibility measurements agree very well with the ladder model [Jrung = -3.10 cm-1 (-4.34 K) and Jrail = -6.02 cm-1 (-8.42 K)]. The assignment as a magnetic ladder is confirmed by first principles bottom-up theoretical calculations which conclude that Jrung = -3.49 cm-1 (-4.89 K) and Jrail = -7.79 cm-1 (-10.9 K), in very good agreement with the experimental values. They also support the absence of additional significant magnetic exchange within the crystals. Thus, (2,3-dmpyH)2CuBr4 represents the second reported example of a weak-exchange limit magnetic ladder (that is, one in which the exchange along the rail is stronger than that across the rung). PMID:17243832

Shapiro, Alexander; Landee, Christopher P; Turnbull, Mark M; Jornet, Joaquim; Deumal, Mercè; Novoa, Juan J; Robb, Michael A; Lewis, William

2007-01-31

375

Crossover from Electromagnetically Induced Transparency to Autler-Townes Splitting in Open Ladder Systems with Doppler Broadening  

CERN Document Server

We propose a general theoretical scheme to investigate the crossover from electromagnetically induced transparency (EIT) to Autler-Townes splitting (ATS) in open ladder-type atomic and molecular systems with Doppler broadening. We show that when the wavenumber ratio $k_c/k_p\\approx -1$, EIT, ATS, and EIT-ATS crossover exist for both ladder-I and ladder-II systems, where $k_c$ ($k_p$) is the wavenumber of control (probe) field. Furthermore, when $k_c/k_p$ is far from $-1$ EIT can occur but ATS is destroyed if the upper state of the ladder-I system is a Rydberg state. In addition, ATS exists but EIT is not possible if the control field used to couple the two lower states of the ladder-II system is a microwave field. The theoretical scheme developed here can be applied to atoms, molecules, and other systems (including Na$_2$ molecules, and Rydberg atoms), and the results obtained may have practical applications in optical information processing and transformation.

Tan, Chaohua

2013-01-01

376

Hood River and Pelton Ladder Evaluation Studies and Hood River Fish Habitat Project, 1998 Annual Progress Report.  

Energy Technology Data Exchange (ETDEWEB)

The Hood River subbasin is home to four species of anadromous salmonids: chinook salmon (Oncorhynchus tshawytscha), coho salmon (Oncorhynchus kisutch), steelhead (Oncorhynchus mykiss), and sea run cutthroat trout (Salmo clarki). Indigenous spring chinook salmon were extirpated during the late 1960's. The naturally spawning spring chinook salmon currently present in the subbasin are progeny of Deschutes stock. Historically, the Hood River subbasin hatchery steelhead program utilized out-of-basin stocks for many years. Indigenous stocks of summer and winter steelhead were listed in March 1998 by National Marine Fisheries Service (NMFS) under the Endangered Species Act (ESA) as a ''Threatened'' Species along with similar genetically similar steelhead in the Lower Columbia Basin.

Lambert, Michael B.; McCanna, Joseph P.; Jennings, Mick

1999-12-01

377

SU(4) spin-orbital two-leg ladder, square, and triangle lattices  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Based on the generalized valence bond picture, a Schwinger boson mean field theory is applied to the symmetric SU(4) spin-orbital systems. For a two-leg SU(4) ladder, the ground state is a spin-orbital liquid with a finite energy gap, in good agreement with recent numerical calculations. In two-dimensional square and triangle lattices, the SU(4) Schwinger bosons condense at (\\pi/2,\\pi/2) and (\\pi/3,\\pi/3), respectively. Spin, orbital, and coupled spin-orbital static suscepti...

Shen, Sq

2002-01-01

378

Snakes and ladders: Localized states in the Swift-Hohenberg equation  

International Nuclear Information System (INIS)

The Swift-Hohenberg equation with cubic and quintic nonlinearities exhibits multiple stable and unstable spatially localized states of arbitrary length in the vicinity of the Maxwell point between spatially homogeneous and periodic states. The even and odd states are organized in a characteristic snaking structure and are connected by branches of mixed parity states forming a ladder-like structure. Numerical computations are used to illustrate the changes in the localized solutions as they grow in spatial extent and to determine the stability and wavelength of the resulting states

379

Magnetic properties of the coupled ladder system $MgV_{2}O_5$  

CERN Document Server

We present magnetic susceptibility measurements on MgV$_2$O$_5$, a compound in which the vanadium oxide planes have the same topology as in CaV$_2$O$_5$. The most striking property is that there is an energy gap of about 15 K, much smaller than in CaV$_2$O$_5$, where the values reported are of the order of 500 K. We show that this may be understood naturally in terms of the phase diagram of the frustrated, coupled ladder system. This analysis leads to the prediction that MgV$_2$O$_5$ should have incommensurate dynamic spin fluctuations.

Millet, P; Bonvoisin, J; Normand, B; Penc, K; Albrecht, M; Mila, F

1998-01-01

380

Effect of pressure on the quantum spin ladder material IPA-CuCl3  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Inelastic neutron scattering and bulk magnetic susceptibility studies of the quantum S=1/2 spin ladder system IPA-CuCl3 are performed under hydrostatic pressure. The pressure dependence of the spin gap $\\Delta$ is determined. At $P=1.5$ GPa it is reduced to $\\Delta=0.79$ meV from $\\Delta=1.17$ meV at ambient pressure. The results allow us to predict a soft-mode quantum phase transition in this system at P$_\\mathrm{c}\\sim 4$ GPa. The measurements are complicated by a proximit...

Hong, Tao; Garlea, V. O.; Zheludev, A.; Fernandez-baca, J.; Manaka, H.; Chang, S.; Leao, J. B.; Poulton, S. J.

2008-01-01

 
 
 
 
381

Field-induced incommensurate phase in the strong-rung spin ladder with ferromagnetic legs  

Science.gov (United States)

We report magnetization, specific heat, and NMR measurements of 3-Br-4-F-V [=3-(3-bromo-4-fluorophenyl)-1,5-diphenylverdazyl], a strong-rung S =1/2 Heisenberg spin ladder with ferromagnetic leg interactions. We explain the magnetic and thermodynamic properties based on the strong-rung regime. Furthermore, we find a field-induced successive phase transition in the specific heat and the nuclear spin-lattice relaxation rate 1/T1. 19F-NMR spectra for higher- and lower-temperature phases indicate partial magnetic order and incommensurate long-range order, respectively, evidencing the presence of frustration due to weak interladder couplings.

Yamaguchi, H.; Miyagai, H.; Yoshida, M.; Takigawa, M.; Iwase, K.; Ono, T.; Kase, N.; Araki, K.; Kittaka, S.; Sakakibara, T.; Shimokawa, T.; Okubo, T.; Okunishi, K.; Matsuo, A.; Hosokoshi, Y.

2014-06-01

382

Ultrafast dynamics of photoinduced phenomena in the spin ladder system NaV2O5  

International Nuclear Information System (INIS)

Recent developments in the study of ultrafast dynamics are reviewed concerning the spin ladder system, ?'-NaV2O5, which is known to have a charge order phase transition accompanying spin dimerization at 34 K. The low energy excitations specific to the low temperature phase is observed by coherent excitation method and their origins are discussed, comparing with the Raman and infrared absorption data. Photoinduced phenomena are studied by transient reflectance and time-resolved Raman spectroscopy and the thermal and nonthermal effects are distinguished by their response time

383

Two-magnon Raman scattering in spin-ladders with exact singlet-rung ground state  

CERN Document Server

We suggest a family of spin-ladder models with exact singlet-rung vacuum. In addition to the terms describing interactions along legs and rungs the Hamiltonian has frustration and cyclic terms. Using coordinate Bethe ansatze all one- and two-dimensional states are constructed. The explicit formula for zero-temperature Raman scattering cross section is derived. The corresponding line-shapes are strongly asymmetric and have no more than one van-Hove singularity. The results are in good agreement with experimental data.

Bibikov, P N

2004-01-01

384

Bethe-Salpeter equations: mesons beyond the rainbow-ladder truncation  

CERN Document Server

We investigate masses of light mesons from a coupled system of Dyson--Schwinger (DSE) and Bethe--Salpeter equations (BSE), taking into account dominant non-Abelian, sub-leading Abelian, and dominant pion cloud contributions to the dressed quark-gluon vertex. The axial-vector Ward-Takahashi identity preserving Bethe-Salpeter kernel is constructed and the spectrum of light mesons calculated. Our model goes significantly beyond the rainbow-ladder. We find that sub-leading Abelian corrections are further dynamically suppressed, and that our results supersede early qualitative predictions from simple truncation schemes.

Williams, Richard

2009-01-01

385

New integral equation for summing Feynman graph series (phi3 ladder graph case)  

International Nuclear Information System (INIS)

The Schwinger parameter formalism is used to derive a new integral equation verified by the sum of the ''open amplitudes'' of the ladder graph series with a phi3 interaction. We prove the existence of a solution to this equation and of the corresponding Green's function. This solution, for any finite value of the coupling constant, is a finite sum of solutions to Fredholm integral equations plus the sum of a convergent series. Its set of singularities is a set of poles from which the spectrum of Regge poles is obtained

386

Defect motion and lattice pinning barriers in Josephson-junction ladders  

International Nuclear Information System (INIS)

We study the motion of domain wall defects in a fully frustrated Josephson-junction ladder system, driven by small applied currents. For small system sizes, the energy barrier EB to the defect motion is computed analytically via symmetry and topological considerations. More generally, we perform numerical simulations directly on the equations of motion, based on the resistively-shunted junction model, to study the dynamics of defects, varying the system size. Coherent motion of domain walls is observed for large system sizes. In the thermodynamical limit, we find EB=0.1827 in units of the Josephson coupling energy

387

Large area VHF plasma production using a ladder-shaped electrode  

International Nuclear Information System (INIS)

VHF excited plasma is produced with a ladder-shaped electrode and the plasma parameters are measured with a heated Langmuir probe. When the discharge frequency (? 100 MHz) of the RF power source is increased, the plasma density increases while the electron temperature decreases. Plasma uniformity less than 15% over 1.2 m x 1.5 m is realized by employing the phase modulation method, that is, the pattern of the standing wave on the electrode can be controlled by changing the phase of the RF power

388

Fish screens at hydroelectric diversions  

International Nuclear Information System (INIS)

Preventing downstream migrating fish from entering the turbines at hydroelectric projects is a standard mitigation goal of state and federal fishery management agencies. The object is to minimize the adverse impacts to the fish associated with the exclusion and passage through the bypass water conveyance facilities. In the western United States, most of the fishery management agencies have fish screen design criteria that focus on the approach and transportational velocities, maximum opening dimensions of the screen material, and the cleaning standards. Recently, more attention has been given to fish behavioral traits such as attraction and sustained and darting swimming speed, which has resulted in more attention to the position of the screens to the flow and the length of time the downstream migrants are exposed to the screens. Criteria for length of time of exposure, size and position of bypass, flow and velocities in the bypass entrances, discharge requirements back into the receiving water, and exposure to predation have created unique challenges to the fish screen designer. This paper discusses some of the more recent types of fixed fish screens that are being installed at hydroelectric plants that meet these challenges

389

Find far fish fast  

Science.gov (United States)

Science author Nicholas Makris from the Massachusetts Institute of Technology helped to create the new fish finding tool. He says that the fish finder will help scientists better understand how fish behave. It will also let scientists calculate the number of fish in different parts of the ocean â a task that is incredibly difficult using current methods for fish counting.

American Association for the Advancement of Science (AAAS;)

2006-02-02

390

Role of bound pairs in the optical properties of highly excited semiconductors a self consistent ladder approximation approach  

CERN Document Server

Presence of bound pairs (excitons) in a low-temperature electron-hole plasma is accounted for by including correlation between fermions at the ladder level. Using a simplified one-dimensional model with on-site Coulomb interaction, we calculate the one-particle self-energies, chemical potential, and optical response. The results are compared to those obtained in the Born approximation, which does not account for bound pairs. In the self-consistent ladder approximation the self-energy and spectral function show a characteristic correlation peak at the exciton energy for low temperature and density. In this regime the Born approximation overestimates the chemical potential. Provided the appropriate vertex correction in the interaction with the photon is included, both ladder and Born approximations reproduce the excitonic and free pair optical absorption at low density, and the disappearance of the exciton absorption peak at larger density. However, lineshapes and energy shifts with density of the absorption an...

Piermarocchi, C

2000-01-01

391

The Deadlock Recovery Problem in the AGV System with the Ladder Guidepath Layout and its Computational Complexity  

Science.gov (United States)

This paper proposes the minimum time deadlock recovery problem in the AGV system with the ladder guidepath layout(DRPL, for short) and analyzes its computational complexity. In order to analyze the computational complexity, this paper introduces the decision problem version of DRPL to ask whether all deadlocks in the AGV system are recoverable within predetermined time, and NP-hardness in a special case of the problem is proved. Moreover, the condition by which the problem becomes NP-hard when the AGV system has a ladder guidepath layout is clarified, and we propose a polynomial time algorithm that solves the optimization problem version of this problem whenever the problem in the ladder guidepath layout is not NP-hard.

Koizumi, Kenji; Masuyama, Shigeru

392

Fish Tales  

Energy Technology Data Exchange (ETDEWEB)

This talk is about fishing and the friendships that have resulted in its pursuit. It is also about theoretical physics, and the relationship of imagination and fantasy to the establishment of ideas about nature. Fishermen, like theoretical physicists, are well known for their inventive imaginations. Perhaps neither are as clever as sailors, who conceived of the mermaid. If one doubts the power of this fantasy, one should remember the ghosts of the many sailors who drowned pursuing these young nymphs. An extraordinary painting by J. Waterhouse is shown as Fig. 1. The enchantment of a mermaid must reflect an extraordinary excess of imagination on the part of the sailor, perhaps together with an impractical turn of mind. A consummated relationship with a mermaid is after all, by its very nature a fantasy incapable of realization. To a theoretical physicist, she is symbolic of many ideas we develop. There are many truths known to fisherman in which one might also find parallels to the goals of scientists: (1) A fish is the only animal that keeps growing after its death; (2) Nothing makes a fish bigger than almost being caught; (3) ''...of all the liars among mankind, the fisherman is the most trustworthy.'' (William Sherwood Fox, in Silken Lines and Silver Hooks); and (4) Men and fish are alike. They both get into trouble when they open their mouths. These quotes may be interpreted as reflecting skepticism regarding the honesty of fisherman, and probably do not reflect adequate admiration for a creative imagination. Is it fair to criticize a person for believing a falsehood that he or she sincerely believes to be true? The fisherman simultaneously invents the lie, and believes in it himself. The parallel with theoretical physics is perhaps only approximate, although we physicists may invent stories that we come to believe, on some rare occasions our ideas actually correspond to a more or less true descriptions of nature. These minor philosophical differences are not really the central issue, however. It is more to the point that both fishermen and scientists enjoy creating a good story, and we also enjoy a story well told. The correct mixture of truth, lie, fantasy and excitement is a witches brew.

McLerran, L.

2010-07-06

393

Field-controlled magnetic order in the quantum spin-ladder system (Hpip)2CuBr4  

DEFF Research Database (Denmark)

Neutron diffraction is used to investigate the field-induced, antiferromagnetically ordered state in the two-leg spin-ladder material (Hpip)(2)CuBr4. This "classical" phase, a consequence of weak interladder coupling, is nevertheless highly unconventional: its properties are influenced strongly by the spin Luttinger-liquid state of the ladder subunits. We determine directly the order parameter (transverse magnetization), the ordering temperature, the spin structure, and the critical exponents around the transition. We introduce a minimal microscopic model for the interladder coupling and calculate the quantum fluctuation corrections to the mean-field interaction.

Christensen, Niels Bech

2009-01-01

394

Energy level ordering and ground state quantum numbers for frustrated two-leg spin-1/2 ladder model  

CERN Document Server

The Lieb-Mattis theorem about ordering of energy levels on bipartite lattices is generalized to two-leg spin-1/2 ladder model frustrated by diagonal interactions. For reflection symmetric model with site-dependent interactions it is proved that the lowest energies in sectors with fixed total spin and reflection quantum numbers are nondegenerate and are monotone increasing as a function of total spin. We prove also that the ground state is unique spin singlet for wide range of coupling constants. Similar results have been obtained for the ladder with arbitrary boundary impurity spin. Some partial results have also been obtained in case of periodical boundary conditions.

Hakobyan, T

2007-01-01

395

Stark-ladder transition in a (GaAs) 5/(AlAs) 2 Zener tunneling diode  

Science.gov (United States)

It has been predicted that resonances between Stark-ladder states and the Zener tunneling current gives rise to oscillatory structure in the derivative of the Zener current. In order to clarify the prediction, we carried out measurements in a p-i-n diode whose intrinsic region consists of a very thin superlattice, and observed oscillatory structure in the second derivative of the current. Electroreflectance (ER) measurements in the same structure were carried out to clarify the relation between the oscillatory structure in the Zener tunneling current and Stark-ladders. The results of the ER measurements are in good agreement with the calculated Zener current.

Nagasawa, H.; Murayama, K.; Morifuji, M.; Di Carlo, A.; Vogl, P.; Böhm, G.; Tränkle, G.; Weimann, G.; Hamaguchi, C.

1996-09-01

396

Staggered-spin contribution to nuclear spin-lattice relaxation in two-leg antiferromagnetic spin-1/2 ladders  

CERN Document Server

We study the nuclear spin-lattice relaxation rate $1/T_1$ in the two-leg antiferromagnetic spin-1/2 Heisenberg ladder. More specifically, we consider the contribution to $1/T_1$ from the processes with momentum transfer $(\\pi,\\pi)$. In the limit of weak coupling between the two chains, this contribution is of activation type with gap $2\\Delta$ at low temperatures ($\\Delta$ is the spin gap), but crosses over to a slowly-decaying temperature dependence at the crossover temperature $T\\approx\\Delta$. This crossover possibly explains the recent high-temperature NMR results on ladder-containing cuprates by T. Imai et al.

Ivanov, D A; Lee, Patrick A.

1998-01-01

397

The impact of product experience, product involvement and verbal processing style on consumers' cognitive structure with regard to fresh fish  

DEFF Research Database (Denmark)

Executive summary 1) The means-end chain model has been widely advocated for the understanding of how consumers perceive self-relevant consequences of products. The model implies that subjective product meaning is established by associations between product attributes and more abstract, more central cognitive categories like values. A means-end chain consists of concrete product attributes, abstract product attributes, functional consequences, psychosocial consequences, instrumental values, a terminal values. 2) The most common method of measuring means-end chains has been the laddering interview technique. Laddering is a semi-qualitative technique which is open for the respondent's own answers without flooding the interviewer with data, as do other qualitative techniques. The results from the laddering interviews are coded and usually presented in a so-called hierarchical value map. 3) However popular, a number of problems with means-end chain analysis have been pointed out. In this paper we report how threevariables affect the outcome of a laddering study, namely (1) product experience, (2) product involvement, and (3) verbal processing style. 4) 90 respondents in the Copenhagen area were interviewed. Respondents were asked to rank four meat types, ie, (1) a fresh, whole, gutted plaice, (2) a package of frozen fish fillets, (3) a whole, frozen chicken, and (4) a package of fresh pork chops, according to how likely it would be that they would use them for a hot meal on a work Respondents were asked to give reasons for the ranking, and from the answers given, laddering procedures were carried out. 5) At the aggregate level, ie when comparing hierarchical value maps across different groups of consumers, the investigation showed that less involved consumers perceived more negative consequences of the consumption of fresh plaice than did the more involved consumers. Fresh fish is perceived to be difficult to get hold of ­ it has to be bought at the fishmonger's ­ di to prepare, and difficult to eat. These aspects are considered time-consuming and result in less time spent with the family. Both the less involved and the more involved consumers regard fresh plaice as healthy. 6) At the individual level, ie when comparing the amount and character of the data provided by the individual respondents, we found that consumers' level of experience had a significant positive relationship with the number of ladders retrieved in the interviews and a significant ne relationship with the proportion of consequence categories. There was no effect on the value categories' share of the total number of categories. As for consumers' level of involvement we found a significant positive correlation with the number of ladders provided in the interviews. Consumers' tendency towards a verbal processing style seemed to have no influence on neither the number of ladders, average length of the ladders, nor the proportion of value categories in the data set. 7) The study seems to indicate that it is possible to employ laddering with consumers withboth higher and lower degrees of involvement and experience. The study also showed that the respondent's capability of verbal processing had no influence on the results. method can therefore not be said to be more or less applicable to respondents with varying degrees of verbal processing ability.

SØrensen, Elin; Grunert, Klaus G.

1996-01-01

398

Thermal conductivity of anisotropic spin-1/2 two leg ladder: Green's function approach  

Science.gov (United States)

We study the thermal transport of a spin-1/2 two leg antiferromagnetic ladder in the direction of legs. The possible effect of spin-orbit coupling and crystalline electric field are investigated in terms of anisotropies in the Heisenberg interactions on both leg and rung couplings. The original spin ladder is mapped to a bosonic model via a bond-operator transformation, where an infinite hard-core repulsion is imposed to constrain one boson occupation per site. The Green's function approach is applied to obtain the energy spectrum of quasi-particle excitations responsible for thermal transport. The thermal conductivity is found to be monotonically decreasing with temperature due to increased scattering among triplet excitations at higher temperatures. A tiny dependence of thermal transport on the anisotropy in the leg direction at low temperatures is observed in contrast to the strong one on the anisotropy along the rung direction, due to the direct effect of the triplet densities. Our results reach asymptotically the ballistic regime of the spin-1/2 Heisenberg chain and present a complement regime for the exact diagonalization data.

Rezania, Hamed; Langari, Abdollah; van Loosdrecht, Paul H. M.; Zotos, Xenophon

2014-08-01

399

Elimination of Oil Residual inside the Copper Pipe Using Ladder Technique  

Directory of Open Access Journals (Sweden)

Full Text Available This study presents the methodology to eliminate oil residual in copper pipe due to rolling process for manufacturing coil used in air conditioner. The pressure caused by Nitrogen flow rate was applied starting from 0, 5, 10, and 15 bar, respectively which was depending on time delay and pipe length. The developed system was divided into 2 modules: Parallel pressure ladder module (PPLM [1] and Serial pressure ladder module (SPLM which were experimented with 2 sizes of copper pipe: diameter 7.29 mm, thickness 0.25 mm, and length 10 km, and diameter 8 mm, thickness 0.25 mm, and length 10 km. From experiment, it can be noted that PPLM would perform better in elimination of oil residual compared to SPLM. About 97.44% (0.04 mg/m and 97.59% (0.05 mg/m of oil residual can be respectively eliminated from diameter 7.29 mm pipe and diameter 8 mm pipe which exceeded the standard allowance of 30% or 0.1 mg/m. Moreover, the cost of Nitrogen can be reduced by 6.25% per month.

Witsarut Sriratana

2013-01-01

400

Charge ordering in quarter-filled ladder systems coupled to the lattice  

CERN Document Server

We investigate charge ordering in the presence of electron-phonon coupling for quarter-filled ladder systems by using Exact Diagonalization. As an example we consider NaV2O5 using model parameters obtained from first-principles band-structure calculations. The relevant Holstein coupling to the lattice considerably reduces the critical value of the nearest-neighbor Coulomb repulsion at which formation of the zig-zag charge-ordered state occurs, which is then accompanied by a static lattice distortion. Energy and length of a kink-like excitation on the background of the distorted lattice are calculated. Spin and charge spectra on ladders with and without static distortion are obtained, and the charge gap and the effective spin-spin exchange parameter J are extracted. J agrees well with experimental results. Analysis of the dynamical Holstein model, restricted to a small number of phonons, shows that low frequency lattice vibrations increase the charge order, accompanied by dynamically produced zig-zag lattice d...

Aichhorn, M; Sherman, E Y; Spitaler, J; Ambrosch-Draxl, C; Evertz, H G

2004-01-01