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Sample records for fish ladder design

  1. Selectivity of fish ladders: a bottleneck in Neotropical fish movement

    OpenAIRE

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

    2007-01-01

    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 thro...

  2. 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)

    Powers, Patrick D.; Orsborn, John F.

    1985-08-01

    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.

  3. Selectivity of fish ladders: a bottleneck in Neotropical fish movement

    Directory of Open Access Journals (Sweden)

    Carlos Sérgio Agostinho

    2007-01-01

    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

  4. Fish ladders: safe fish passage or hotspot for predation?

    OpenAIRE

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

    2012-01-01

    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 pr...

  5. Fish ladders: safe fish passage or hotspot for predation?

    Directory of Open Access Journals (Sweden)

    Angelo Antonio Agostinho

    2012-10-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Orsborn, John F.

    1985-08-01

    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)

  7. Selectivity of fish ladders: a bottleneck in Neotropical fish movement

    Scientific Electronic Library Online (English)

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

    Full Text Available 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, Psectrogaster amazonica and Oxydoras niger). Although the ma

  8. Fish ladders: safe fish passage or hotspot for predation?

    Scientific Electronic Library Online (English)

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

    2012-10-01

    Full Text Available 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 suggested that the high density of fish in the restricted ladd

  9. 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 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)

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

    Scientific Electronic Library Online (English)

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

    2004-08-01

    Full Text Available 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.

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

    Directory of Open Access Journals (Sweden)

    Domingo Rodriguez Fernandez

    2004-08-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Sérgio Makrakis

    2007-01-01

    Full Text Available 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 along 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 migratory species sampled, four were recorded ascending and descending, and three species only ascending the ladder. The fish ladder appears to selectively favor species with high swimming capabilities. A discussion is presented on the requirements for future research on attraction to the fish ladder entrance, downstream movements, fish utilization of the ladder, and impacts on spawning and rearing habitat both upstream and downstream of the dam.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 tanques 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

  13. 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)

    Luiz Gustavo Martins da Silva

    2012-10-01

    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

  14. 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)

    Aaserude, Robert G.; Orsborn, John F.

    1985-08-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Angelo Antônio Agostinho

    2007-01-01

    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

  16. 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)

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

    2012-10-01

    Full Text Available 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 distribution throughout different stretches. Generally, t

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

    Scientific Electronic Library Online (English)

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

    Full Text Available 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 migratory species sampled, four were recorded ascending and de

  18. 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)

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

    Full Text Available 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.

  19. 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)

    Domingo Rodriguez Fernandez

    2007-01-01

    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.

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

    Scientific Electronic Library Online (English)

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

    Full Text Available 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 migratory species; we also determined the abundance and

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

    Directory of Open Access Journals (Sweden)

    Mark D. Bowen

    2006-06-01

    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.

  2. Assessments to determine the effect of current and alternate ladder operations on brood stock collection and behavior of hatchery fall Chinook Salmon at Spring Creek National Fish Hatchery during 2003-2005

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Spring Creek National Fish Hatchery traditionally operates an adult ladder, without closure, from the start of the tule fall Chinook salmon run in late August until...

  3. Fish friendly designs

    International Nuclear Information System (INIS)

    A new fish-friendly facility at the McNary dam on the Columbia river is described. Originally the fish were provided for by a conventional fishladder, a vertical fishlock, a holding pond and an auxiliary water supply. The system was poor and resulted in the loss of 90% of smolts swimming downstream through the auxiliary water supply system. The problems were alleviated by Harza Engineering of Illinois and Atkinson Construction of California: the new system is described. (UK)

  4. 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)

    Domingo Rodrigues Fernandez

    2007-01-01

    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

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

    Scientific Electronic Library Online (English)

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

    Full Text Available 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.

  6. 29 CFR 1910.27 - Fixed ladders.

    Science.gov (United States)

    2010-07-01

    ... OCCUPATIONAL SAFETY AND HEALTH STANDARDS Walking-Working Surfaces § 1910.27 Fixed ladders. (a) Design...) Fastenings. Fastenings shall be an integral part of fixed ladder design. (4) Splices. All splices made...

  7. 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)

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

    2014-01-01

    Full Text Available 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

  8. Student Achievement and Career Ladder Status.

    Science.gov (United States)

    Dickson, LouAnn

    The Career Ladder Teacher Incentive Program was designed by the Arizona legislature to attract, motivate, and retain talented teachers with both professional recognition and monetary incentives. The program was also intended to improve student achievement. Using carefully matched samples of career-ladder and non-career-ladder teachers in Mesa…

  9. First Catch Your Fish: Designing a “Low Energy Fish” Label

    Directory of Open Access Journals (Sweden)

    Andy Grinnall

    2015-05-01

    Full Text Available This paper explores the application of information design principles to label design for fish packaging, identifying energy implications for the product. This stage of the project has consisted of: A review and distillation of the relevant literature on information and label design; environmental and labelling standards; and literature on consumer reaction to the design and information content of the label. Considering the design of a label requires the analysis and integration of a variety of factors while attempting to satisfy the demands of consumers and retailers.

  10. 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)

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

    2001-02-01

    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.

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

    OpenAIRE

    Richmond, Marshall C.; Joanne P.; Thomas J. Carlson; Zhiqun Deng

    2007-01-01

    Fish passing through dams may be injured or killed despite advances in turbine design, project operations and other fish bypass systems. The six-degree-of-freedom (6DOF) Sensor Fish device is an autonomous sensor package that characterizes the physical conditions and physical stresses to which fish are exposed when they pass through complex hydraulic environments. It has been used to identify the locations and operations where conditions are severe enough to injure or kill fish. During the de...

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

    Scientific Electronic Library Online (English)

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

    2012-10-01

    Full Text Available 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

    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.)

  14. Hole doped Hubbard ladders

    OpenAIRE

    Fehske, H.; Hager, G; Wellein, G.; Jeckelmann, E.

    2005-01-01

    The formation of stripes in six-leg Hubbard ladders with cylindrical boundary conditions is investigated for two different hole dopings, where the amplitude of the hole density modulation is determined in the limits of vanishing DMRG truncation errors and infinitely long ladders. The results give strong evidence that stripes exist in the ground state of these systems for strong but not for weak Hubbard couplings. The doping dependence of these findings is analysed.

  15. Hole doped Hubbard ladders

    CERN Document Server

    Fehske, H; Wellein, G; Jeckelmann, E

    2006-01-01

    The formation of stripes in six-leg Hubbard ladders with cylindrical boundary conditions is investigated for two different hole dopings, where the amplitude of the hole density modulation is determined in the limits of vanishing DMRG truncation errors and infinitely long ladders. The results give strong evidence that stripes exist in the ground state of these systems for strong but not for weak Hubbard couplings. The doping dependence of these findings is analysed.

  16. Design and testing of small scale fish meat bone separator useful for fish processing.

    Science.gov (United States)

    Ali Muhammed, M; Manjunatha, N; Murthy, K Venkatesh; Bhaskar, N

    2015-06-01

    The present study relates to the food processing machinery and, more specifically machine for producing boneless comminuted meat from raw fish fillet. This machine is of belt and drum type meat bone separator designed for small scale fish processing in a continuous mode. The basic principal involved in this machine is compression force. The electric geared motor consists of 1HP and the conveyor belt has a linear velocity of 19 to 22 m min(-1), which was sufficient to debone the fish effectively. During the meat bone separation trials an efficiency up to 75 % on dressed fish weight basis was observed and with a capacity to separate 70 kg h(-1) of meat from fish at the machine speed of 25 rpm. During the trials, it was demonstrated that there was no significant change in the proximate composition of comminuted fish meat when compared to unprocessed fish meat. This design has a greater emphasis on hygiene, provision for cleaning-in-place (CIP) and gives cost effective need and reliability for small scale industries to produce fish meat in turn used for their value added products. PMID:26028734

  17. Fish swarm optimization algorithm applied to engineering system design

    Scientific Electronic Library Online (English)

    Fran Sérgio, Lobato; Valder, Steffen Jr..

    2014-01-01

    Full Text Available 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.

  18. 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 (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

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

    Directory of Open Access Journals (Sweden)

    Marshall C. Richmond

    2007-11-01

    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.

  20. Low bandgap ladder polymers

    Energy Technology Data Exchange (ETDEWEB)

    Kertesz, Miklos [Dept. of Chemistry, Georgetown Univ., Washington, DC (United States); Hughbanks, T.R. [Dept. of Chemistry, Texas A and M Univ., College Station, TX (United States)

    1995-03-01

    Unique new ladder polymers consisting of condensed succession of six and five membered conjugated carbon rings have been made recently by Scherf and Muellen. Seven topological isomers of these polyindenoindenes are considered theoretically. The results are analyzed in terms of topological bandgaps and geometry relaxation. Three isomers are expected to have a bandgap smaller than 0.2eV, although the possibility of a ferrimagnetic ground state for these can not be ruled out. (orig.)

  1. Novel design solutions for fishing reel mechanisms

    Science.gov (United States)

    Lovasz, Erwin-Christian; Modler, Karl-Heinz; Neumann, Rudolf; Gruescu, Corina Mihaela; Perju, Dan; Ciupe, Valentin; Maniu, Inocentiu

    2015-07-01

    Currently, there are various reels on the market regarding the type of mechanism, which achieves the winding and unwinding of the line. The designers have the purpose of obtaining a linear transmission function, by means of a simple and small-sized mechanism. However, the present solutions are not satisfactory because of large deviations from linearity of the transmission function and complexity of mechanical schema. A novel solution for the reel spool mechanism is proposed. Its kinematic schema and synthesis method are described. The kinematic schema of the chosen mechanism is based on a noncircular gear in series with a scotch-yoke mechanism. The yoke is driven by a stud fixed on the driving noncircular gear. The drawbacks of other models regarding the effects occurring at the ends of the spool are eliminated through achieving an appropriate transmission function of the spool. The linear function approximation with curved end-arches appropriately computed to ensure mathematical continuity is very good. The experimental results on the mechanism model validate the theoretical approach. The developed mechanism solution is recorded under a reel spool mechanism patent.

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

    International Nuclear Information System (INIS)

    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.

  3. Design and construction of an Electric Fish Finder

    Scientific Electronic Library Online (English)

    William G. R., Crampton; Jonathan K., Wells; Charles, Smyth; Steven A., Walz.

    2007-09-01

    Full Text Available Nós fornecemos o esquema e as instruções para a construção de um Detector de Peixes Elétricos - um amplificador portátil de banda larga utilizado para detectar os campos elétricos de peixes gymnotiformes. Este aparelho pode ser adaptado para encontrar peixes elétricos em diversos ambientes aquáticos [...] . É resistente, à prova d'água e energizado por baterias alcalinas. Esta contribuição faz parte de uma série de artigos técnicos que pretende encorajar estudantes de ictiologia neotropical a explorar a ecologia, sistemática e comunicação elétrica de peixes gymnotiformes. Abstract in english We provide notes on the design and construction of an Electric Fish Finder - a portable differential amplifier for detecting the electrostatic fields of gymnotiform knifefishes. The device can be adapted to locate electric fishes in any kind of aquatic environment. It is rugged, water resistant, and [...] powered by alkaline batteries. This contribution is part of a series of technical papers designed to encourage students of neotropical ichthyology to explore the ecology, systematics, and electric signaling of gymnotiform fishes.

  4. Superconducting ladders take breather

    International Nuclear Information System (INIS)

    One of the more unusual phenomena predicted to occur in nonlinear media is the breather - a state in which energy is strongly localized in one place and does not diffuse to other regions of the system. Now experimental groups at the Massachusetts Institute of Technology and the University of Zaragoza in Spain (E Trias et al. Phys. Rev. Lett. 84 741) and at the University of Erlangen and the Max Planck Institute in Dresden (P Binder et al. Phys. Rev. Lett. 84 745) have observed a particular type of breather - known as a rotating discrete breather in a ''ladder'' of superconducting junctions. In this article the author presents the latest experimental research into nonlinear media. (UK)

  5. Hole-doped Hubbard ladders

    Energy Technology Data Exchange (ETDEWEB)

    Fehske, H. [Institut fuer Physik, Ernst-Moritz-Arndt-Universitaet Greifswald, D-17487 Greifswald (Germany)]. E-mail: fehske@physik.uni-greifswald.de; Hager, G. [Regionales Rechenzentrum Erlangen, Martensstr. 1, D-91058 Erlangen (Germany); Wellein, G. [Regionales Rechenzentrum Erlangen, Martensstr. 1, D-91058 Erlangen (Germany); Jeckelmann, E. [Institut fuer Physik, Johannes-Gutenberg-Universitaet Mainz, D-55099 Mainz (Germany)

    2006-05-01

    The formation of stripes in six-leg Hubbard ladders with cylindrical boundary conditions is investigated for two different hole dopings, where the amplitude of the hole-density modulation is determined in the limits of vanishing density-matrix renormalisation group truncation errors and infinitely long ladders. The results give strong evidence that stripes exist in the ground state of these systems for strong but not for weak Hubbard couplings. The doping dependence of these findings is analysed.

  6. A Review and Modern Approach to LC Ladder Synthesis

    Directory of Open Access Journals (Sweden)

    Alexander J. Casson

    2011-01-01

    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.

  7. Laddering em pesquisa de marketing / Laddering in marketing research

    Scientific Electronic Library Online (English)

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

    2008-03-01

    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 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.

  8. Assessments to determine the effect of current and alternate ladder operations on brood stock collection and behavior of hatchery fall Chinook Salmon at Little White Salmon National Fish Hatchery during 2004-05

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Production of upriver bright fall Chinook salmon at Little White Salmon National Fish Hatchery was introduced as part of the John Day Dam mitigation program in the...

  9. Ladder-Type Circuits Revisited

    Science.gov (United States)

    Yoon, Sung Hyun

    2007-01-01

    Ladder-type circuits where a given unit is repeated infinitely many times are dealt with in many textbooks on electromagnetism as examples of filter circuits. Determining the impedance of such circuits seems to be regarded as simple, which may be due to the fact that the invariance of the infinite system under the operation of adding one more unit…

  10. Design, Implementation and Control of a Fish Robot with Undulating Fins

    OpenAIRE

    Mohsen Siahmansouri; Ahmad Ghanbari; Mir Masoud Seyyed Fakhrabadi

    2011-01-01

    Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the over...

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

    OpenAIRE

    Santoshkumar; Vishal Hiremath

    2012-01-01

    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 t...

  12. Design of multisegmented freeform lens for LED fishing/working lamp with high efficiency.

    Science.gov (United States)

    Lai, Min-Feng; Quoc Anh, Nguyen Doan; Gao, Jia-Zhi; Ma, Hsin-Yi; Lee, Hsiao-Yi

    2015-10-01

    A novel LED fishing/working light is proposed to enhance the lighting efficiency of a fishing boat. The study is focused on the freeform secondary lens design so as to create a lamp that attracts fish and sheds light on the deck for the crew's work. The experimental results show that the proposed multisegmented freeform lens can deliver the proposed aim, giving 3 times as much illuminating power as the traditional high-intensity discharge fishing lamp does with the same input of electrical power. PMID:26479667

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

    OpenAIRE

    Rossi, Claudio; Colorado Montaño, Julián; Coral Cuellar, William; Barrientos Cruz, Antonio

    2011-01-01

    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 o...

  14. Discrete Breathers in Josephson Ladders

    OpenAIRE

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

    2001-01-01

    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 ...

  15. Compact design of fish processing equipment and implementation of lean tools

    OpenAIRE

    Sharapov, Sergei

    2013-01-01

    Following master thesis “Compact design of fish processing equipment and implementation of lean tools” contains description and technical information about newly developed fish processing equipment which includes 122 sub-assemblies and 626 parts. Completely new technical documentation was created and used to manufacture real and functional prototype. Main goal is to design new robust module, create correct and functional technical documentation, implementing new technical solution based on re...

  16. 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

  17. Exactly solvable quantum spin tubes and ladders

    OpenAIRE

    Batchelor, M. T.; Maslen, M.

    1999-01-01

    We find families of integrable n-leg spin-1/2 ladders and tubes with general isotropic exchange interactions between spins. These models are equivalent to su(N) spin chains with N=2^n. Arbitrary rung interactions in the spin tubes and ladders induce chemical potentials in the equivalent spin chains. The potentials are n-dependent and differ for the tube and ladder models. The models are solvable by means of nested Bethe Ansatz.

  18. Developing and implementing a career ladder program.

    Science.gov (United States)

    Wall, Michelle

    2007-01-01

    A career ladder program is a formal management tool used not only by managers looking to recognize and retain employees, but also by employees seeking growth opportunities. A career ladder program involves careful development, frequent and effective communication during implementation, and activities focused on measuring program effectiveness. Career ladders are a way to increase productivity and staff versatility; improve morale, clinical quality, and staff satisfaction; reduce turnover; promote professional growth and job enrichment; and improve patient care. PMID:17696072

  19. Fish Farm Challenge Provides STEM Design Experiences for Youth

    Science.gov (United States)

    Horton , Robert L.; House, Patty L.

    2015-01-01

    In 2014, Monsanto Corporation partnered with National 4-H Council to help inspire and develop professional skills among young agriculturalists. The Ohio State University created Fish Farm Challenge, which engaged more than 8,000 youth across eight states. Youth were taught about worldwide food insecurity and the importance of aquaculture. They…

  20. A New Polyether Ladder Compound Produced by the Dinoflagellate Karenia brevis

    OpenAIRE

    Bourdelais, Andrea J; Henry M. Jacocks; Wright, Jeffrey L.C.; Bigwarfe, Paul M.; Baden, Daniel G

    2005-01-01

    A new ladder-frame polyether compound containing five fused ether rings was isolated from laboratory cultures of the marine dinoflagellate Karenia brevis. This compound, named brevenal, and its dimethyl acetal derivative both competitively displace brevetoxin from its binding site in rat brain synaptosomes. Significantly, these compounds are also nontoxic to fish and antagonize the toxic effects of brevetoxins in fish. The structure and biological activity of brevenal, as well as the dimethyl...

  1. 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

  2. Validation of a Contemplation Ladder in an Adult Substance Use Disorder Sample

    OpenAIRE

    HOGUE, AARON; Dauber, Sarah; Morgenstern, Jon

    2010-01-01

    Developing brief measures of motivation to abstain from substance use that reliably predict treatment retention and outcome is a high priority in the addiction field. This study examined the psychometric properties of a contemplation ladder designed to assess readiness to abstain from alcohol and drug use respectively, based on the contemplation ladder for smoking cessation developed by Biener & Abrams (1991). Participants were 394 substance-using male and female welfare recipients referred f...

  3. 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)

  4. Discrete Breathers in Josephson Ladders

    CERN Document Server

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

    2001-01-01

    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...

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

    Directory of Open Access Journals (Sweden)

    Santoshkumar

    2012-05-01

    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.

  6. Evolutionary multiobjective design of a flexible caudal fin for robotic fish.

    Science.gov (United States)

    Clark, Anthony J; Tan, Xiaobo; McKinley, Philip K

    2015-01-01

    Robotic fish accomplish swimming by deforming their bodies or other fin-like appendages. As an emerging class of embedded computing system, robotic fish are anticipated to play an important role in environmental monitoring, inspection of underwater structures, tracking of hazardous wastes and oil spills, and the study of live fish behaviors. While integration of flexible materials (into the fins and/or body) holds the promise of improved swimming performance (in terms of both speed and maneuverability) for these robots, such components also introduce significant design challenges due to the complex material mechanics and hydrodynamic interactions. The problem is further exacerbated by the need for the robots to meet multiple objectives (e.g., both speed and energy efficiency). In this paper, we propose an evolutionary multiobjective optimization approach to the design and control of a robotic fish with a flexible caudal fin. Specifically, we use the NSGA-II algorithm to investigate morphological and control parameter values that optimize swimming speed and power usage. Several evolved fin designs are validated experimentally with a small robotic fish, where fins of different stiffness values and sizes are printed with a multi-material 3D printer. Experimental results confirm the effectiveness of the proposed design approach in balancing the two competing objectives. PMID:26601975

  7. Mechanical design, fabrication, and test of biomimetic fish robot using LIPCA as artificial muscle

    Science.gov (United States)

    Wiguna, T.; Syaifuddin, M.; Park, Hoon C.; Heo, S.

    2006-03-01

    This paper presents a mechanical design, fabrication and test of biomimetic fish robot using the Lightweight Piezocomposite Curved Actuator (LIPCA). We have designed a mechanism for converting actuation of the LIPCA into caudal fin movement. This linkage mechanism consists of rack-pinion system and four-bar linkage. We also have tested four types of caudal fin in order to examine effect of different shape of caudal fin on thrust generation by tail beat. Subsequently, based on the caudal fin test, four caudal fins which resemble fish caudal fin shapes of ostraciiform, subcarangiform, carangiform and thunniform, respectively, are attached to the posterior part of the robotic fish. The swimming test using 300 V pp input with 1 Hz to 1.5 Hz frequency was conducted to investigate effect of changing tail beat frequency and shape of caudal fin on the swimming speed of the robotic fish. The maximum swimming speed was reached when the device was operated at its natural swimming frequency. At the natural swimming frequency 1 Hz, maximum swimming speeds of 1.632 cm/s, 1.776 cm/s, 1.612 cm/s and 1.51 cm/s were reached for ostraciiform-, subcarangiform-, carangiform- and thunniform-like caudal fins, respectively. Strouhal numbers, which are a measure of thrust efficiency, were calculated in order to examine thrust performance of the present biomimetic fish robot. We also approximated the net forward force of the robotic fish using momentum conservation principle.

  8. Design and Development of an Innovative Mobile Fish Vending Unit for Retailers

    OpenAIRE

    Bikash Sarkar; B.B.Sahu; B.C.Mohapatra; N.K.Barik,; D.Majhi; P. Jayasankar,; P.R.Bhatnagar

    2013-01-01

    The purpose of this study was to design and develop a low cost mobile fish vending unit in urban/municipality areas with proper waste disposal. The prototype model was designed and fabricated using locally available materials at a cost of Rs.52780/-. The main feature of this prototype is that its100 and 70 L insulated chilled crates; utility box; Cutting and processing area; storage of water and waste disposal. Necessary effort has been made to maintain the possible market quality of fish and...

  9. TEST OF LADDERS AND STEP-LADDERS AT SMALL ENTERPRISES AS THE ELEMENT OF WORK SAFETY ASSURANCE / ????????? ??????? ? ????????? ?? ????? ???????????? ? ????????????? ??? ??????? ??????????? ???????????? ?????

    Directory of Open Access Journals (Sweden)

    Senchenko Vladimir Aleksandrovich / ???????? ???????? ?????????????

    2015-02-01

    Full Text Available One of the main means of lifting on height at small enterprises in construction branch are ladders and step-ladders. Therefore regular tests of ladders and step-ladders regarding safety of the use in work is an important task in the sphere of safety of works at height / ????? ?? ???????? ??????? ??????? ?? ?????? ?? ????? ???????????? ???????????? ??????? ???????? ???????? ? ?????????. ??????? ?? ?????????? ????????? ?? ??????? ???????????? ????????????? ? ?????? ???????? ???????????? ??????? ? ????? ??????????? ???????????? ????? ?? ??????

  10. Experimental evidence of variable-order behavior of ladders and nested ladders

    OpenAIRE

    Sierociuk, Dominik; Podlubny, Igor; Petras, Ivo

    2011-01-01

    The experimental study of two kinds of electrical circuits, a domino ladder and a nested ladder, is presented. While the domino ladder is known and already appeared in the theory of fractional-order systems, the nested ladder circuit is presented in this article for the first time. For fitting the measured data, a new approach is suggested, which is based on using the Mittag-Leffler function and which means that the data are fitted by a solution of an initial-value problem f...

  11. Design and Management Criteria for Fish, Amphibian, and Reptile Communities Within Created Agricultural Wetlands

    Science.gov (United States)

    Design and management criteria for created agricultural wetlands in the midwestern United States typically focus on maximizing the ability to process agricultural runoff. Ecological benefits for fish, amphibian, and reptiles are often secondary considerations. One example of this water quality focu...

  12. Design, Implementation and Control of a Fish Robot with Undulating Fins

    Directory of Open Access Journals (Sweden)

    Mohsen Siahmansouri

    2011-11-01

    Full Text Available Biomimetic robots can potentially perform better than conventional robots in underwater vehicle designing. This paper describes the design of the propulsion system and depth control of a robotic fish. In this study, inspired by knife fish, we have designed and implemented an undulating fin to produce propulsive force. This undulating fin is a segmental anal fin that produces sinusoidal wave to propel the robot. The relationship between the individual fin segment and phase angles with the overall fin trajectory has also been discussed. This propulsive force can be adjusted and directed for fish robot manoeuvre by a mechanical system with two servomotors. These servomotors regulate the direction and depth of swimming. A wireless remote control system is designed to adjust the servomotors which enables us to control revolution, speed and phase differences of neighbor servomotors of fins. Finally, Field trials are conducted in an outdoor pool to demonstrate the relationship between robotic fish speed and fin parameters like phase difference, the number of phase and undulatory amplitude.

  13. 29 CFR 1917.119 - Portable ladders.

    Science.gov (United States)

    2010-07-01

    ...shall be removed from the worksite: (i) Broken, split or missing rungs, cleats or steps; (ii) Broken or split side rails; (iii) Missing...runways or scaffolds. (3) Metal and wire-reinforced ladders with wooden side...

  14. A seventeenth-order polylogarithm ladder

    CERN Document Server

    Bailey, D H; Bailey, David H.; Broadhurst, David J.

    1999-01-01

    Cohen, Lewin and Zagier found four ladders that entail the polylogarithms ${\\rm Li}_n(\\alpha_1^{-k}):=\\sum_{r>0}\\alpha_1^{-k r}/r^n$ at order $n=16$, with indices $k\\le360$, and $\\alpha_1$ being the smallest known Salem number, i.e. the larger real root of Lehmer's celebrated polynomial with the smallest known non-trivial Mahler measure. By adjoining the index $k=630$, we generate a fifth ladder at order 16 and a ladder at order 17 that we presume to be unique. This empirical integer relation, between elements of multiplied by integers with nearly 300 digits. It has been checked to more than 59,000 decimal digits. Among the ladders that we found in other number fields, the longest has order 13 and index 294. It is based on be the largest eigenvalue of the adjacency matrix of a graph.

  15. Magnetic order in ferromagnetically coupled spin ladders

    CERN Document Server

    Dalosto, S D

    1999-01-01

    A model of coupled antiferromagnetic spin-1/2 Heisenberg ladders is studied with numerical techniques. In the case of ferromagnetic interladder coupling we find that the dynamic and static structure factor has a peak at $(\\pi,\\pi/2)$ where the first (second) direction is along (transversal) to the ladders. Besides, we suggest that the intensity of this peak and the spin-spin correlation at the maximum distance along the ladder direction remain finite in the bulk limit for strong enough interladder coupling. We discuss the relevance of these results for magnetic compounds containing ladders coupled in a trellis lattice and for the stripe scenario in high-T$_c$ superconducting cuprates.

  16. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  18. Analysis of Environmental Issues Related to Small-Scale Hydroelectric Development II: Design Consideration for Passing Fish Upstream Around Dams

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, S. G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bell, M. C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Anderson, J. J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Richey, E. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Parkhurst, Z. E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    1980-08-01

    The purpose of this report is to provide general information for use by potential developers of small scale hydroelectric projects that will include facilities to pass migrating fish upstream around dams. The document is not intended to be a textbook on design of fish passage facilities, but rather to be a general guide to some factors that are important when designing such facilities.

  19. The transient ladder synchronization of chaotic systems

    Energy Technology Data Exchange (ETDEWEB)

    Chen, H.-K. [Department of Industrial Engineering and Management, Hsiuping Institute of Technology, No. 11, Gungye Rd., Dali City, Taichung, Taiwan (China)]. E-mail: kanechen@giga.net.tw; Sheu, L.-J. [Department of Mechanical Engineering, Chung Hua University, Hsinchu, Taiwan (China)]. E-mail: ljsheu@chu.edu.tw

    2006-07-03

    A new type for chaotically synchronizing systems, transient ladder chaos synchronization, is proposed in this Letter. For some physical systems, chaotic synchronization is possible in only some of the variables. It is shown that, for the non-synchronizing variable, synchronization up to a constant difference for t{sub 1}=ladder chaos synchronization and anti-synchronization are illustrated by using two identical chaotic Froude pendulums. Numerical simulations are shown for demonstration.

  20. DUNDRUM Restriction and Intrusion Liberty Ladders (DRILL)

    OpenAIRE

    KENNEDY, HARRY

    2011-01-01

    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...

  1. Stripe formation in doped Hubbard ladders

    OpenAIRE

    Hager, G; Wellein, G.; Jeckelmann, E.; Fehske, H.

    2004-01-01

    We investigate the formation of stripes in $7\\chunks \\times 6$ Hubbard ladders with $4\\chunks$ holes doped away from half filling using the density-matrix renormalization group (DMRG) method. A parallelized code allows us to keep enough density-matrix eigenstates (up to $m=8000$) and to study sufficiently large systems (with up to $7\\chunks = 21$ rungs) to extrapolate the stripe amplitude to the limits of vanishing DMRG truncation error and infinitely long ladders. Our wor...

  2. Generalized Binomial States: Ladder Operator Approach

    OpenAIRE

    Fu, Hong-Chen; SASAKI, Ryu

    1996-01-01

    We show that the binomial states (BS) of Stoler {\\it et al.} admit the ladder and displacement operator formalism. By generalizing the ladder operator formalism we propose an eigenvalue equation which possesses the number and the squeezed states as its limiting solutions. The explicit forms of the solutions, to be referred to as the {\\it generalized binomial states} (GBS), are given. Corresponding to the wide range of the eigenvalue spectrum these GBS have as widely differen...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

    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.

  4. Design of extended length submerged traveling screen and submerged bar screen fish guidance equipment

    International Nuclear Information System (INIS)

    The hydropower projects on the Snake and lower Columbia Rivers in the Pacific Northwest are unique because these rivers are also the spawning grounds for migratory salmon. The salmon swim upstream from the ocean, lay their eggs, and die. The newly hatched fingerlings must then make their way past the hydroelectric dams to the ocean. Two separate bypass systems are needed, one to pass the adult fish going upstream, and one to pass the fingerlings going downstream. This paper addresses the design considerations for two of the components of the downstream migrant fish passage facilities, the extended Submerged Traveling Screen and Submerged Bar Screen

  5. Effect of spray nozzle design on fish oil-whey protein microcapsule properties.

    Science.gov (United States)

    Legako, Jerrad; Dunford, Nurhan Turgut

    2010-08-01

    Microencapsulation improves oxidative stability and shelf life of fish oil. Spray and freeze drying are widely used to produce microcapsules. Newer spray-nozzles utilize multiple fluid channels allowing for mixing of wall and core materials at the point of atomization. Sonic energy has also been employed as a means of atomization. The objective of this study was to examine the effect of nozzle type and design on fish oil encapsulation efficiency and microcapsule properties. A total of 3 nozzle types, a pressure nozzle with 1 liquid channel, a pressure nozzle with 2 liquid channels, and a sonic atomizer with 2 liquid channels were examined for their suitability to encapsulate fish oil in whey protein isolate. Physical and chemical properties of freeze dried microcapsules were compared to those of microcapsules produced by spray drying. The 2-fluid pressure and ultrasonic nozzles had the highest (91.6%) and the lowest microencapsulation efficiencies (76%), respectively. There was no significant difference in bulk density of microcapsules produced by ultrasonic and 3-fluid pressure nozzles. The ultrasonic nozzle showed a significantly narrower particle size distribution than the other nozzles. This study demonstrated that new nozzle designs that eliminate emulsion preparation prior to spray drying can be beneficial for microencapsulation applications. However, there is still a need for research to improve microencapsulation efficiency of multiple channel spray nozzles. Practical Application: Since this research evaluates new spray nozzle designs for oil microencapsulation, the information presented in this article could be an interest to fish oil producers and food industry. PMID:20722925

  6. Design and Development of an Innovative Mobile Fish Vending Unit for Retailers

    Directory of Open Access Journals (Sweden)

    Bikash Sarkar

    2013-02-01

    Full Text Available The purpose of this study was to design and develop a low cost mobile fish vending unit in urban/municipality areas with proper waste disposal. The prototype model was designed and fabricated using locally available materials at a cost of Rs.52780/-. The main feature of this prototype is that its100 and 70 L insulated chilled crates; utility box; Cutting and processing area; storage of water and waste disposal. Necessary effort has been made to maintain the possible market quality of fish and fish products in the form of raw and semi-processed/processed chilled products. Test trial of ergonomics evaluation indicated that the working heart rate (HR work of the male operator ranged from 123.8 to 134 beats/min with a mean value of 131.9 ± 1.6 beats/min. The corresponding values with women were 119.0 to 149.6 and 131.2 ± 1.0 beats/min, respectively. The heart rate was lower with male as compared to the female. The forces on the pedal are 161.84 N and 377.6 N in case of first and second condition. The calculated mechanical advantages for first and second condition are 0.278 and 0.276, respectively. The design of mobile fish vending unit is stable. The operators both male and female have found the unit to be conducive both in terms of ergonomically as well as operationally.

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

    Directory of Open Access Journals (Sweden)

    Wang R.W.

    2010-02-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Knapp, Suzanne M.

    1993-03-01

    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).

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  10. 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)

  11. Dipoles on a Two-leg Ladder

    DEFF Research Database (Denmark)

    Gammelmark, SØren; Zinner, Nikolaj Thomas

    2013-01-01

    We study polar molecules with long-range dipole-dipole interactions confined to move on a two-leg ladder for different orientations of the molecular dipole moments with respect to the ladder. Matrix product states are employed to calculate the many-body ground state of the system as function of lattice filling fractions, perpendicular hopping between the legs, and dipole interaction strength. We show that the system exhibits zig-zag ordering when the dipolar interactions are predominantly repulsive. As a function of dipole moment orientation with respect to the ladder, we find that there is a critical angle at which ordering disappears. This angle is slightly larger than the angle at which the dipoles are non-interacting along a single leg. This behavior should be observable using current experimental techniques.

  12. Pair Correlations in Doped Hubbard Ladders

    CERN Document Server

    Dolfi, Michele; Keller, Sebastian; Troyer, Matthias

    2015-01-01

    Hubbard ladders are an important stepping stone to the physics of the two-dimensional Hubbard model. While many of their properties are accessible to numerical and analytical techniques, the question of whether weakly hole-doped Hubbard ladders are dominated by superconducting or charge-density-wave correlations has so far eluded a definitive answer. In particular, previous numerical simulations of Hubbard ladders have seen a much faster decay of superconducting correlations than expected based on analytical arguments. We revisit this question using a state-of-the-art implementation of the density matrix renormalization group algorithm that allows us to simulate larger system sizes with higher accuracy than before. Performing careful extrapolations of the results, we obtain improved estimates for the Luttinger liquid parameter and the correlation functions at long distances. Our results confirm that, as suggested by analytical considerations, superconducting correlations become dominant in the limit of very s...

  13. Non-Abelian String-Net Ladders

    CERN Document Server

    Schulz, M D; Vidal, J

    2014-01-01

    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.

  14. A seventeenth-order polylogarithm ladder

    OpenAIRE

    Bailey, David H.; Broadhurst, David J.

    1999-01-01

    Cohen, Lewin and Zagier found four ladders that entail the polylogarithms ${\\rm Li}_n(\\alpha_1^{-k}):=\\sum_{r>0}\\alpha_1^{-k r}/r^n$ at order $n=16$, with indices $k\\le360$, and $\\alpha_1$ being the smallest known Salem number, i.e. the larger real root of Lehmer's celebrated polynomial $\\alpha^{10}+\\alpha^9-\\alpha^7-\\alpha^6-\\alpha^5-\\alpha^4-\\alpha^3+\\alpha+1$, with the smallest known non-trivial Mahler measure. By adjoining the index $k=630$, we generate a fifth ladder at...

  15. Generalized binomial states: ladder operator approach

    Science.gov (United States)

    Fu, Hong-Chen; Sasaki, Ryu

    1996-09-01

    We show that the binomial states (BS) of Stoler et al admit the ladder and displacement operator formalism. By generalizing the ladder operator formalism we propose an eigenvalue equation which possesses the number and the squeezed states as its limiting solutions. The explicit forms of the solutions, to be referred to as the generalized binomial states (GBS), are given. Corresponding to the wide range of the eigenvalue spectrum these GBS have as widely different properties. Their limits to number and squeezed states are investigated in detail. The time evolution of BS is obtained as a special case of the approach.

  16. 30 CFR 56.11006 - Fixed ladder landings.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fixed ladder landings. 56.11006 Section 56....11006 Fixed ladder landings. Fixed ladders shall project at least 3 feet above landings, or subtantial handholds shall be provided above the landings....

  17. 30 CFR 57.11006 - Fixed ladder landings.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fixed ladder landings. 57.11006 Section 57... Escapeways Travelways-Surface and Underground § 57.11006 Fixed ladder landings. Fixed ladders shall project at least 3 feet above landings, or substantial handholds shall be provided above the landings....

  18. The Static Ladder Problem with Two Sources of Friction

    Science.gov (United States)

    Bennett, Jonathan; Mauney, Alex

    2011-01-01

    The problem of a ladder leaning against a wall in static equilibrium is a classic example encountered in introductory mechanics texts. Most discussions of this problem assume that the static frictional force between the ladder and wall can be ignored. A few authors consider the case where the static friction coefficients between ladder/wall…

  19. Development of Single- and Double-sided Ladders for the ILD Vertex Detectors

    OpenAIRE

    Baudot, Jerome; Bashinska, Olena; Chon-Sen, Nathalie; Dulinski, Wojciech; Hegner, Franziska; Gelin-Galibel, Marie; Gauld, Rhorry; Goffe, Mathieu; Goldstein, Joel; Gregor, Ingrid; Hu-Guo, Christine; Koetz, Ulrich; Nomerotski, Andrei; Winter, Marc

    2012-01-01

    We discuss two projects exploring the integration of thin CMOS pixel sensors in order to prototype ladders matching the geometry needed for the ILD vertex detector. The PLUME project has designed and fabricated full-size and fully functional double- sided layers which currently reach 0.6 % X0 and aim for 0.3 % X0 in mid-2012. Another approach, SERNWIETE, consists in wrapping the sensors in a polyimide-based micro-cable to obtain a supportless single-sided ladder with a mater...

  20. Development of Single- and Double-sided Ladders for the ILD Vertex Detectors

    CERN Document Server

    Baudot, Jerome; Chon-Sen, Nathalie; Dulinski, Wojciech; Hegner, Franziska; Gelin-Galibel, Marie; Gauld, Rhorry; Goffe, Mathieu; Goldstein, Joel; Gregor, Ingrid; Hu-Guo, Christine; Koetz, Ulrich; Nomerotski, Andrei; Winter, Marc

    2012-01-01

    We discuss two projects exploring the integration of thin CMOS pixel sensors in order to prototype ladders matching the geometry needed for the ILD vertex detector. The PLUME project has designed and fabricated full-size and fully functional double- sided layers which currently reach 0.6 % X0 and aim for 0.3 % X0 in mid-2012. Another approach, SERNWIETE, consists in wrapping the sensors in a polyimide-based micro-cable to obtain a supportless single-sided ladder with a material budget around 0.15 % X0. First promising samples have been produced and the full-size prototype is expected in spring 2012.

  1. A portable bio-amplifier for electric fish research: design and construction

    Scientific Electronic Library Online (English)

    Jonathan K., Wells; William G. R., Crampton.

    2006-06-01

    Full Text Available As fracas descargas dos órgãos elétricos (EODs) dos gimnotiformes podem ser facilmente amplificadas com um amplificador de banda larga conectado a eletrodos submersos. A saída do amplificador pode ser monitorada com auto-falantes ou digitalizada para análise subsequente. Equipamentos disponíveis com [...] ercialmente são caros e requerem fontes elétricas potentes. Nós fornecemos aqui o esquema e as instruções para a construção e calibragem de um bio-amplificador barato, portátil, energizado à bateria recarregável. Este equipamento foi desenhado para permitir a localização de peixes elétricos no campo, além de permitir a aquisiçào relativamente sem ruídos de ondas de EODs de espécimes mantidos temporariamente em cativeiro. Esta contribuição pretende encorajar estudantes de Ictiologia Neotropical a explorar sinais elétricos em peixes gymnotiformes. Abstract in english The weak electric organ discharges (EODs) of gymnotiform knife fishes can be readily amplified with a wideband amplifier connected to submerged electrodes. The output from such an amplifier can then be monitored with audio speakers or digitized for subsequent analysis. Commercially available devices [...] are expensive and usually require mains electrical power. Here we provide design notes and instructions for the construction and calibration of a cheap, portable, battery-powered, AC-coupled wideband bio-amplifier. This device was designed to allow electric fishes to be located in the field, and also to permit the relatively noise-free acquisition of EOD waveforms from specimens held in temporary captivity. This contribution is intended to encourage students of neotropical ichthyology to explore electric signaling in gymnotiform fishes.

  2. Design and Implementation of a new Autonomous Sensor Fish to Support Advanced Hydropower Development

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Zhiqun; Lu, Jun; Myjak, Mitchell J.; Martinez, Jayson J.; Tian, Chuan; Morris, Scott J.; Carlson, Thomas J.; Zhou, Da; Hou, Hongfei

    2014-11-04

    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 wider range of turbine designs and operating environments. It provides in situ measurements of three dimensional (3D) 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. It is being deployed to evaluate the biological effects of turbines or other hydraulic structures in several countries.

  3. Raman cross section of spin ladders

    OpenAIRE

    Jurecka, Christoph; Gruetzun, Verena; Friedrich, Andreas; Brenig, Wolfram

    2001-01-01

    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.

  4. 29 CFR 1915.72 - Ladders.

    Science.gov (United States)

    2010-07-01

    ...1) The use of ladders with broken or missing rungs or steps, broken or split side rails, or...each rail with three 10d common wire nails or fastened with through...each rail with five 10d common wire nails or fastened with...

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

    Directory of Open Access Journals (Sweden)

    Erika da Silva Maciel

    2014-06-01

    Full Text Available 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.

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

    Scientific Electronic Library Online (English)

    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

    Full Text Available 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.

  7. Design and control of an embedded vision guided robotic fish with multiple control surfaces.

    Science.gov (United States)

    Yu, Junzhi; Wang, Kai; Tan, Min; Zhang, Jianwei

    2014-01-01

    This paper focuses on the development and control issues of a self-propelled robotic fish with multiple artificial control surfaces and an embedded vision system. By virtue of the hybrid propulsion capability in the body plus the caudal fin and the complementary maneuverability in accessory fins, a synthesized propulsion scheme including a caudal fin, a pair of pectoral fins, and a pelvic fin is proposed. To achieve flexible yet stable motions in aquatic environments, a central pattern generator- (CPG-) based control method is employed. Meanwhile, a monocular underwater vision serves as sensory feedback that modifies the control parameters. The integration of the CPG-based motion control and the visual processing in an embedded microcontroller allows the robotic fish to navigate online. Aquatic tests demonstrate the efficacy of the proposed mechatronic design and swimming control methods. Particularly, a pelvic fin actuated sideward swimming gait was first implemented. It is also found that the speeds and maneuverability of the robotic fish with coordinated control surfaces were largely superior to that of the swimming robot propelled by a single control surface. PMID:24688413

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

    Directory of Open Access Journals (Sweden)

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

    2010-10-01

    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.

  9. Using ergonomic digital human modeling in evaluation of workplace design and prevention of occupational hazards onboard fishing vessels

    OpenAIRE

    Zhang, Bing; Álvarez Casado, Enrique; Tello Sandoval, Sonija; Mondelo, Pedro

    2010-01-01

    This paper seeks to present methods for improving the occupational health and safety of Spanish fishermen, and for redesigning the workplace onboard small fishing vessels. To achieve its objective, the research project was designed in four steps: First, the equipment and procedures for catching, handling, and storing fish was studied. Second, the work postures of all the fishermen were simulated and assessed by using an ergonomic digital human modeling system (ManneQuin Pro). ...

  10. Fractional Shapiro steps in ladder Josephson arrays

    International Nuclear Information System (INIS)

    We study the response of Josephson ladder arrays (1xN plaquettes) to a combined ac and dc current. For N?1, the arrays are predicted to exhibit Shapiro steps at voltages left-angle V right-angle=nN??/(2e) for n=1/2,1,3/2, . . ., over a broad range of fields f=?/?0 (?=flux per plaquette, ?0=hc/2e). The calculated half-steps persist even in single-plaquette ''arrays'' at all fields f?0, and, when the critical currents parallel to the applied current are sufficiently unequal, even at f=0. Measurements of the step widths ?I1/2(f) and ?I1(f) for 1x600 ladder arrays of Nb-Au-Nb junctions are in good agreement with the calculations

  11. SUSY's Ladder: Reframing Sequestering at Large Volume

    CERN Document Server

    Reece, Matthew

    2015-01-01

    Theories with approximate no-scale structure, such as the Large Volume Scenario, have a distinctive hierarchy of multiple mass scales in between TeV gaugino masses and the Planck scale, which we call SUSY's Ladder. This is a particular realization of Split Supersymmetry in which the same small parameter suppresses gaugino masses relative to scalar soft masses, scalar soft masses relative to the gravitino mass, and the UV cutoff or string scale relative to the Planck scale. This scenario has many phenomenologically interesting properties, and can avoid dangers including the gravitino problem, flavor problems, and the moduli-induced LSP problem that plague other supersymmetric theories. We study SUSY's Ladder using a superspace formalism that makes the mysterious cancelations in previous computations manifest. This opens the possibility of a consistent effective field theory understanding of the phenomenology of these scenarios, based on power-counting in the small ratio of string to Planck scales. We also show...

  12. Stripe formation in doped Hubbard ladders

    CERN Document Server

    Hager, G; Jeckelmann, E; Fehske, H

    2004-01-01

    We investigate the formation of stripes in $7\\chunks \\times 6$ Hubbard ladders with $4\\chunks$ holes doped away from half filling using the density-matrix renormalization group (DMRG) method. A parallelized code allows us to keep enough density-matrix eigenstates (up to $m=8000$) and to study sufficiently large systems (with up to $7\\chunks = 21$ rungs) to extrapolate the stripe amplitude to the limits of vanishing DMRG truncation error and infinitely long ladders. Our work gives strong evidence that stripes exist in the ground state for strong coupling ($U=12t$) but that the structures found in the hole density at weaker coupling ($U=3t$) are an artifact of the DMRG approach.

  13. Clinical ladder program implementation: a project guide.

    Science.gov (United States)

    Ko, Yu Kyung; Yu, Soyoung

    2014-11-01

    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

  14. Stakeholder Participation in Research Design and Decisions: Scientists, Fishers, and Mercury in Saltwater Fish

    OpenAIRE

    Burger, Joanna; Gochfeld, Michael; Fote, Tom

    2013-01-01

    Individuals who fish and eat self-caught fish make decisions about where to fish, the type to eat, and the quantity to eat. Federal and state agencies often issue consumption advisories for some fish with high mercury (Hg) concentrations, but seldom provide either the actual metal levels to the general public, or identify the fish that have low contaminant levels. Community participatory research is of growing importance in defining, studying, and resolving complex exposure and risk issues, a...

  15. Hood River and Pelton Ladder Evaluation Studies, Annual Report 2000-2001.

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Erik

    2009-09-01

    The Bonneville Power Administration (BPA) funded the development of two master plans which outline the rationale, and general approach, for implementing a defined group of projects that are an integral part of a comprehensive watershed goal to 'Protect, enhance and restore wild and natural populations of anadromous and resident fish within the Hood River Subbasin'. The Hood River Production Master Plan and the Pelton Ladder Master Plan were completed in 1991 and subsequently approved by the Northwest Power Planning Council in 1992. Action items identified in the two master plans, as well as in a later document entitled 'Hood River/Pelton Ladder Master Agreement' (ODFW and CTWSRO Undated), are designed to achieve two biological fish objectives: (1) to increase production of wild summer and winter steelhead (Oncorhynchus mykiss) to levels commensurate with the subbasins current carrying capacity and (2) re-establishing a self-sustaining population of spring chinook salmon (Oncorhynchus tshawytscha). Numerical fish objectives for subbasin escapement, spawner escapement, and subbasin harvest are defined for each of these species in Coccoli (2000). Several projects are presently funded by the BPA to achieve the Hood River subbasin's numerical fish objectives for summer and winter steelhead and spring chinook salmon. They include BPA project numbers 1998-021-00 (Hood River Fish Habitat), 1998-053-03 (Hood River Production Program - CTWSRO: M&E), 1998-053-07 (Parkdale Fish Facility), 1998-053-08 (Powerdale/Oak Springs O&M), and 1998-053-12 (Hood River Steelhead Genetics Study). Collectively, they are implemented under the umbrella of what has come to be defined as the Hood River Production Program (HRPP). The HRPP is jointly implemented by the Oregon Department of Fish and Wildlife (ODFW) and The Confederated Tribes of the Warm Springs Reservation of Oregon (CTWSRO). Strategies for achieving the HRPP's biological fish objectives for the Hood River subbasin were initially devised based on various assumptions about (1) subbasin carrying capacity, (2) survival rates for selected life history stages, and (3) historic and current escapements of wild, natural, and hatchery stocks of anadromous salmonids to the Hood River subbasin. The Oregon Department of Fish and Wildlife began funding a monitoring and evaluation (M&E) project in December 1991 to collect the quantitative biological information needed to (1) more accurately assess the validity of these assumptions and (2) evaluate the proposed hatchery supplementation component of the HRPP. Bonneville Power Administration assumed funding of the M&E project in August 1992. The M&E project was initially confined to sampling anadromous salmonids escaping to an adult trapping facility operated at Powerdale Dam; which is located at River Mile (RM) 4.5 on the mainstem of the Hood River. Stock specific life history and biological data was collected to (1) monitor subbasin spawner escapements and (2) collect pre-implementation data critical to evaluating the newly proposed HRPP's potential biological impact on indigenous populations of resident fish. The scope of the M&E project was expanded in 1994 to collect the data needed to quantify (1) subbasin smolt production and carrying capacity, (2) smolt to adult survival rates, and (3) the spatial distribution of indigenous populations of summer and winter steelhead, spring and fall chinook salmon, and coho salmon. A creel was incorporated into the M&E project in December 1996 to evaluate the HRPP with respect to its defined subbasin and spawner escapement objectives for Hood River stocks of wild and hatchery summer and winter steelhead and for natural and Deschutes stock hatchery spring chinook salmon. In 1996, the M&E project also began monitoring streamflow at various locations in the Hood River subbasin. Streamflow data will be used to correlate subbasin smolt production with summer streamflows. Data collected from 1991-1999 is reported in the following annual progress report

  16. Braess like Paradox on Ladder Network

    CERN Document Server

    Toyota, Norihito

    2015-01-01

    Braess \\cite{1} has been studied about a traffic flow on a diamond type network and found that introducing new edges to the networks always does not achieve the efficiency. Some researchers studied the Braess' paradox in similar type networks by introducing various types of cost functions. But whether such paradox occurs or not is not scarcely studied in complex networks except for Dorogovtsev-Mendes network\\cite{2}. In this article, we study the paradox on Ladder type networks, as the first step to the research about Braess' paradox on Watts and Strogatz type small world network\\cite{Watt1}\\cite{Watt2}. %We theoretically and numerically studied Braess' paradox on Ladder networks. For the purpose, we construct $4 \\times 3$ models as extensions of the original Braess' models. We analyze theoretically and numerically studied the models on Ladder networks. Last we give a phase diagram for (a) model, where the cost functions of bypasses are constant =0 or flow, base on two parameters $r$ and $p$ by numerical simu...

  17. Quantum Monte Carlo Study of Weakly Coupled Spin Ladders

    OpenAIRE

    Kim, Y. J.; Birgeneau, R. J.; Kastner, M. A.; Lee, Y. S.; Endoh, Y.; Shirane, G.; Yamada, K.

    1999-01-01

    We report a quantum Monte Carlo study of the thermodynamic properties of arrays of spin ladders with various widths ($n$), coupled via a weak inter-ladder exchange coupling $\\alpha J$, where $J$ is the intra-ladder coupling both along and between the chains. This coupled ladder system serves as a simplified model for the magnetism of presumed ordered spin and charge stripes in the two-dimensional CuO$_2$ planes of hole-doped copper oxides. Our results for $n=3$ with weak int...

  18. Healthcare organization-education partnerships and career ladder programs for health care workers.

    Science.gov (United States)

    Dill, Janette S; Chuang, Emmeline; Morgan, Jennifer C

    2014-12-01

    Increasing concerns about quality of care and workforce shortages have motivated health care organizations and educational institutions to partner to create career ladders for frontline health care workers. Career ladders reward workers for gains in skills and knowledge and may reduce the costs associated with turnover, improve patient care, and/or address projected shortages of certain nursing and allied health professions. This study examines partnerships between health care and educational organizations in the United States during the design and implementation of career ladder training programs for low-skill workers in health care settings, referred to as frontline health care workers. Mixed methods data from 291 frontline health care workers and 347 key informants (e.g., administrators, instructors, managers) collected between 2007 and 2010 were analyzed using both regression and fuzzy-set qualitative comparative analysis (QCA). Results suggest that different combinations of partner characteristics, including having an education leader, employer leader, frontline management support, partnership history, community need, and educational policies, were necessary for high worker career self-efficacy and program satisfaction. Whether a worker received a wage increase, however, was primarily dependent on leadership within the health care organization, including having an employer leader and employer implementation policies. Findings suggest that strong partnerships between health care and educational organizations can contribute to the successful implementation of career ladder programs, but workers' ability to earn monetary rewards for program participation depends on the strength of leadership support within the health care organization. PMID:25441318

  19. Using career ladders to motivate and retain employees: an implementation success story.

    Science.gov (United States)

    Garletts, Joseph A

    2002-01-01

    In October 2000, Phoenix-based Sonora Quest Laboratories, LLC (SQL), commissioned The Gelfond Group to survey SQL employees. Responding to negative survey scores, SQL developed and implemented an entry-level career ladder for line staff of the specimen management/referral testing department. The program was piloted in February 2001, and was implemented fully shortly thereafter. The ladder was designed to provide job enrichment opportunities through company-conducted training and advancement provisions. It contained requirements for productivity and quality of work performed in addition to increasingly rigorous training and competency documentation. Employees were accountable for their own advancement and for ensuring that all documentation was complete. Advancement was automatic once requirements were completed. Pay increases accompanied each advancement on a predetermined scale. At the end of 12 months, employee turnover dropped from 39% to less than 20% annually. Both productivity and morale improved, and results on a second employee survey indicated dramatic improvement in five key areas. The career ladder concept has been replicated successfully in several other departments, including phlebotomy, and a six-tiered ladder is under development for the clinical laboratory. It will encompass CLA, MLT, and MT positions from entry level to technical coordinator. PMID:12506829

  20. Sodium-reduced lean sausages with fish oil optimized by a mixture design approach.

    Science.gov (United States)

    Marchetti, L; Argel, N; Andrés, S C; Califano, A N

    2015-06-01

    A partial NaCl replacement by KCl and sodium tripolyphosphate on low-fat meat sausages formulated with fish oil was studied using a mixture design. Thermal behavior by modulated differential scanning calorimetry, physicochemical, and textural properties were determined; afterwards they were mathematically modeled as a function of salts content. The thermo-rheological behavior of the different formulations was also studied in a control-stress rheometer. The optimal sodium reduction was found employing a desirability function approach. This formulation was experimentally validated and employed for microstructure analysis by environmental scanning microscopy. The results obtained in this work revealed that partial sodium replacement affected the matrix microstructure, but this change had no impact on sensory acceptability. In comparison with US and Argentinean commercial sausages, our product has 58% and 70% less Na(+) respectively. PMID:25725284

  1. Education System and the "Ladder of Success"

    OpenAIRE

    Ueda, Akiko

    2004-01-01

    Since the launch of development activities in 1961, English medium education seems to have replaced literacy in Dzongkha and Choeky as the means of climbing up the ladder of success. It appears that young people's preferences for a kind of education system, a training institute, and a course they choose is responsive to the government grading system of the civil service. It in turn means that the civil service grading system is a valid means to give incentives and dis-incentives to selected a...

  2. Bound states in weakly disordered spin ladders

    OpenAIRE

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

    2004-01-01

    We study the appearance of bound states in the spin gap of spin-1/2 ladders induced by weak bond disorder. Starting from the strong-coupling limit, i.e., the limit of weakly coupled dimers, we perform a projection on the single-triplet subspace and derive the position of bound states for the single impurity problem of one modified coupling as well as for small impurity clusters. The case of a finite concentration of impurities is treated with the coherent-potential approxima...

  3. Larval dispersal and movement patterns of coral reef fishes, and implications for marine reserve network design.

    Science.gov (United States)

    Green, Alison L; Maypa, Aileen P; Almany, Glenn R; Rhodes, Kevin L; Weeks, Rebecca; Abesamis, Rene A; Gleason, Mary G; Mumby, Peter J; White, Alan T

    2015-11-01

    Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1-0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5-3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3-10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5-15 km, and self-recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of marine reserves in tropical marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) marine reserves should be more than twice the size of the home range of focal species (in all directions), thus marine reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside reserves; (ii) reserve spacing should be <15 km, with smaller reserves spaced more closely; and (iii) marine reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts. PMID:25423947

  4. 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

  5. Inhomogeneously doped two-leg ladder systems

    CERN Document Server

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

    2002-01-01

    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.

  6. Bound states in weakly disordered spin ladders

    Energy Technology Data Exchange (ETDEWEB)

    Arlego, M. [Departamento de Fisica, Universidad Nacional de La Plata, CC 67 (1900) La Plata (Argentina)]. E-mail: arlego@venus.fisica.unlp.edu.ar; Brenig, W. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Cabra, D.C. [Laboratoire de Physique Theorique, Universite Louis Pasteur Strasbourg (France); Heidrich-Meisner, F. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Honecker, A. [Institut fuer Theoretische Physik, Technische Universitaet Braunschweig (Germany); Rossini, G. [Departamento de Fisica, Universidad Nacional de La Plata, CC 67 (1900) La Plata (Argentina)

    2005-04-30

    We study the appearance of bound states in the spin gap of spin-12 ladders induced by weak bond disorder. Starting from the strong-coupling limit, i.e., the limit of weakly coupled dimers, we perform a projection on the single-triplet subspace and derive the position of bound states for the single impurity problem of one modified coupling as well as for small impurity clusters. The case of a finite concentration of impurities is treated with the coherent-potential approximation (CPA) in the strong-coupling limit and compared with numerical results. Further, we analyze the details in the structure of the density of states and relate their origin to the influence of impurity clusters.

  7. Bound states in weakly disordered spin ladders

    CERN Document Server

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

    2005-01-01

    We study the appearance of bound states in the spin gap of spin-1/2 ladders induced by weak bond disorder. Starting from the strong-coupling limit, i.e., the limit of weakly coupled dimers, we perform a projection on the single-triplet subspace and derive the position of bound states for the single impurity problem of one modified coupling as well as for small impurity clusters. The case of a finite concentration of impurities is treated with the coherent-potential approximation in the strong-coupling limit and compared with numerical results. Furthermore, we analyze the details in the structure of the density of states and relate their origin to the influence of impurity clusters.

  8. Magnetizing and heating quantum spin ladders

    Indian Academy of Sciences (India)

    Andrey Zheludev

    2008-11-01

    Quasi-one-dimensional quantum spin liquids, such as weakly coupled even-legged S=1/2 spin ladders or spin tubes, have a singlet non-magnetic ground state and gap in the excitation spectrum. Their low-temperature properties can be described in terms of triplet massive quasiparticles. These magnons possess some unique features due to the peculiar topology of one dimension. For example, two-particle interactions totally destroy single-particle states for certain energy and momentum transfers, resulting in the so-called termination of the magnon spectrum. At high field a Bose–Einstein condensation of these magnons produces a `quantum spin solid' phase, where `conventional` antiferromagnetic order coexists with excitations that are totally outside conventional spin wave theory. At finite temperatures strong repulsion between quasiparticles leads to a universal renormalization of their masses and lifetimes. These diverse phenomena are best probed by neutron scattering experiments that directly measure the spin correlation functions and excitation spectra.

  9. Thévenin equivalents for inhomogeneous ladder networks of generators

    International Nuclear Information System (INIS)

    We find general formulas for Thévenin equivalents (equivalent voltage and equivalent impedance) for inhomogeneous ladder networks of generators defined as a voltage source and an impedance in series. In the projective matrix representation, this is accomplished by adopting a special decomposition of a 3 × 3 transfer matrix which transforms a product of transfer matrices to a product of diagonal matrices up to a prefactor and a postfactor. In particular, we calculate Thévenin equivalents in a closed form for two ladder networks of generators with a periodic transfer matrix of period 1 (tapered ladder network) and period 2. (paper)

  10. Installaton of a fish migration channel for spawning at Itaipu

    International Nuclear Information System (INIS)

    The objective of installing a fish migration channel for spawning at the Itaipu hydroelectric station on the Parana river between Brazil and Paraguay is to improve fish recovery downstream from the dam. Preliminary data from the first phase has proved the efficiency of an experimental project, with the entry and ascendancy of fish in a migration channel ladder. These data now provide the technical basis for implementation of the complementary spawning channel stage. (author)

  11. Nonperturbative study of generalized ladder graphs in a \\phi^2\\chi theory

    OpenAIRE

    Nieuwenhuis, Taco; Tjon, J.A.

    1996-01-01

    The Feynman-Schwinger representation is used to construct scalar-scalar bound states for the set of all ladder and crossed-ladder graphs in a \\phi^2\\chi theory in (3+1) dimensions. The results are compared to those of the usual Bethe-Salpeter equation in the ladder approximation and of several quasi-potential equations. Particularly for large couplings, the ladder predictions are seen to underestimate the binding energy significantly as compared to the generalized ladder cas...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-12-30

    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.

  13. Entanglement in resonating valence bond states: ladder versus isotropic lattices

    Energy Technology Data Exchange (ETDEWEB)

    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

    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)

  14. 29 CFR 1918.24 - Fixed and portable ladders.

    Science.gov (United States)

    2010-07-01

    ...shall be removed from the vessel: (i) Broken, split or missing rungs, cleats or steps; (ii) Broken or split side rails; (iii) Missing...runways or scaffolds. (6) Metal and wire-reinforced ladders (even with...

  15. Ladder operators and differential equations for multiple orthogonal polynomials

    OpenAIRE

    Filipuk, Galina; Van Assche, Walter; Zhang, Lun

    2012-01-01

    In this paper, we obtain the ladder operators and associated compatibility conditions for the type I and the type II multiple orthogonal polynomials. These ladder equations extend known results for orthogonal polynomials and can be used to derive the differential equations satisfied by multiple orthogonal polynomials. Our approach is based on Riemann-Hilbert problems and the Christoffel-Darboux formula for multiple orthogonal polynomials, and the nearest-neighbor recurrence ...

  16. Thermal drag in spin ladders coupled to phonons

    OpenAIRE

    Bartsch, Christian; Brenig, Wolfram

    2013-01-01

    We study the spin-phonon drag effect in the magnetothermal transport of spin-1/2 two-leg ladders coupled to lattice degrees of freedom. Using a bond operator description for the triplon excitations of the spin ladder and magnetoelastic coupling to acoustic phonons, we employ the time convolutionless projection operator method to derive expressions for the diagonal and off-diagonal thermal conductivities of the coupled two-component triplon-phonon system. We find that for mag...

  17. Development and benefits of a pharmacy technician career ladder.

    Science.gov (United States)

    Strozyk, W R; Underwood, D A

    1994-03-01

    The development and benefits of a career ladder for pharmacy technicians are described. A career ladder for technicians was implemented at a 575-bed community hospital in 1989 to provide incentives for technicians to improve their skills and take on additional responsibilities. The ladder consisted of four steps, each requiring additional years of experience, proficiency at specific skills, and involvement in specific departmental activities (e.g., maintaining floor-stock medications, preparing i.v. admixtures, and implementing new policies and procedures). Pay increases were given with each move up the ladder. At the start of the program, eight technicians were placed at level 2 and the remaining 16 were placed at level 1. Three years after the ladder was implemented, annual technician turnover had decreased from 33% to 15%. Employee surveys suggested increased job satisfaction among the technicians. Reassignment of tasks to technicians (e.g., maintaining narcotic distribution and coordinating daily purchasing activities) increased scheduling flexibility and helped provide an additional eight hours per week for pharmacist involvement in patient care activities. A pharmacy technician career ladder was associated with lower technician turnover, expansion of technicians' job responsibilities, and an increase in pharmacists' time for clinical activity. PMID:8203386

  18. Lock and Dam No. 9 : Arkansas River, Arkansas : Supplement No. 2 to Design Memorandum No. 1, General Fish and Wildlife Facilities at Holla Bend National Wildlife Refuge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This supplement is prepared in compliance with instructions included in 2d endorsement ENGCWEZ dated 9 June 1965 to the transmittal letter for Design Memorandum No....

  19. Essential Fish Habitat (EFH) Areas Protected From Fishing

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Designated Essential Fish Habitat (EFH) areas where fishing or the use of fishing gears has been restricted or modified in order to minimize the adverse effects of...

  20. 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)

    Alison M. Hutson

    2012-10-01

    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.

  1. 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)

    Coll-Serrano, Vicente

    2012-01-01

    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.

  2. 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

  3. On the Impact of Cepheid Outliers on the Distance Ladder

    CERN Document Server

    Becker, M R; Rozo, E; Marshall, P; Rykoff, E S

    2015-01-01

    Recent work by Efstathiou (2014) highlighted the importance of outliers in the period-luminosity (PL) relation of Cepheid data on the distance ladder. We present a statistical framework designed to address this difficulty, and apply it to the Cepheid data from the Milky Way (MW), the Large Magellanic Cloud (LMC), and the Riess et al. (2011) (hereafter R11) dataset. We consider two possible models of the outlier population in the R11 Cepheid dataset. One of these models exhibits tension between the PL relation of the R11 cepheids and the MW+LMC cepheids, while the other does not. We extend our models to adequately account for tension between the cepheid data sets when appropriate. Our outlier treatment has a significant impact on the distance scales to Supernovae hosts with Cepheid distances, increasing the uncertainty in these distances by a median factor of ~30%. We further find that our Cepheid outlier treatment translates into a modest, but non-negligible increase in the statistical uncertainty of H0, addi...

  4. Meet the surrogate fish

    International Nuclear Information System (INIS)

    This article gives details of the US Department of Energy's innovative research into the development of a sensor system that will work as a surrogate fish to provide information to aid the design of fish-friendly turbines for hydroelectric power plants. The selection of the dams for the testing of sensor fish, the release and recovery of the sensor fish, the recording of the physical forces exerted on fish as they pass through the turbines, and use of the information gathered to build more sensor fish are discussed. Fish investigations conducted at the Pacific Northwest National Laboratory are briefly described. (UK)

  5. The Effects of Laddering and Spinning in Underwriter Manipulation of IPOs

    OpenAIRE

    Ludwig Chincarini; Alex Etzkowitz; Jonathan Kadish

    2012-01-01

    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 con...

  6. Design and fish culture considerations for catfish farming in split ponds

    Science.gov (United States)

    Split ponds are simple, pond-based aquaculture systems constructed by dividing an existing catfish pond into two unequal basins with an earthen levee. Fish are confined in the smaller basin (usually about 15-20% of total water area) while the larger basin serves as a waste-treatment lagoon. A high-v...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-12-01

    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.

  8. Evaluation of Fish Passage Sites in the Walla Walla River Basin, 2008

    Energy Technology Data Exchange (ETDEWEB)

    Chamness, Mickie A. [Pacific Northwest National Laboratory

    2008-08-29

    In 2008, Pacific Northwest National Laboratory evaluated the Hofer Dam fish screen and provided technical assistance at two other fish passage sites as requested by the Bonneville Power Administration, the Walla Walla Watershed Council, or the Confederated Tribes of the Umatilla Indian Reservation. Evaluation of new sites such as Hofer Dam focuses on their design, construction, operation, and maintenance to determine if they effectively provide juvenile salmonids with safe passage through irrigation diversions. There were two requests for technical assistance in 2008. In the first, the Confederated Tribes of the Umatilla Indian Reservation requested an evaluation of the Nursery Bridge fish screens associated with the fish ladder on the east side of the Walla Walla River. One set of brushes that clean the screens was broken for an extended period. Underwater videography and water velocity measurements were used to determine there were no potential adverse effects on juvenile salmonids when the west set of screens was clean enough to pass water normally. A second request, received from the National Marine Fisheries Service and the Walla Walla Watershed Council, asked for evaluation of water velocities through relatively new head gates above and adjacent to the Eastside Ditch fish screens on the Walla Walla River. Water moving through the head gates and not taken for irrigation is diverted to provide water for the Nursery Bridge fish ladder on the east side of the river. Elevations used in the design of the head gates were incorrect, causing excessive flow through the head gates that closely approached or exceeded the maximum swimming burst speed of juvenile salmonids. Hofer Dam was evaluated in June 2008. PNNL researchers found that conditions at Hofer Dam will not cause impingement or entrainment of juvenile salmonids but may provide habitat for predators and lack strong sweeping flows to encourage juvenile salmonid passage downstream. Further evaluation of velocities at the Eastside Ditch and wasteway gates should occur as changes are made to compensate for the design problems. These evaluations will help determine whether further changes are required. Hofer Dam also should be evaluated again under more normal operating conditions when the river levels are typical of those when fish are emigrating and the metal plate is not affecting flows.

  9. Method- and species-specific detection probabilities of fish occupancy in Arctic lakes: Implications for design and management

    Science.gov (United States)

    Haynes, Trevor B.; Rosenberger, Amanda E.; Lindberg, Mark S.; Whitman, Matthew; Schmutz, Joel A.

    2013-01-01

    Studies examining species occurrence often fail to account for false absences in field sampling. We investigate detection probabilities of five gear types for six fish species in a sample of lakes on the North Slope, Alaska. We used an occupancy modeling approach to provide estimates of detection probabilities for each method. Variation in gear- and species-specific detection probability was considerable. For example, detection probabilities for the fyke net ranged from 0.82 (SE = 0.05) for least cisco (Coregonus sardinella) to 0.04 (SE = 0.01) for slimy sculpin (Cottus cognatus). Detection probabilities were also affected by site-specific variables such as depth of the lake, year, day of sampling, and lake connection to a stream. With the exception of the dip net and shore minnow traps, each gear type provided the highest detection probability of at least one species. Results suggest that a multimethod approach may be most effective when attempting to sample the entire fish community of Arctic lakes. Detection probability estimates will be useful for designing optimal fish sampling and monitoring protocols in Arctic lakes.

  10. The fish fauna in the fish passage at the Ourinhos Dam, Paranapanema River

    Scientific Electronic Library Online (English)

    Marlene Sofia, Arcifa; André Luiz Henríques, Esguícero.

    2012-10-01

    Full Text Available A composição e abundância da ictiofauna da escada de peixes da barragem de Ourinhos, a mais nova hidrelétrica (fechada em 2005) na sequência de barragens construídas no rio Paranapanema, foram avaliadas três vezes em um ciclo diário, em três períodos de coleta, dois no verão e um no inverno de 2008- [...] 2009. A escada foi fechada e esvaziada e os peixes coletados e identificados, antes da devolução da maior parte deles a jusante. A ictiofauna da escada foi comparada à do reservatório de Ourinhos, coletada na mesma época. Vinte e sete espécies e 4862 indivíduos foram coletados na escada. Pimelodus maculatus foi a única espécie migradora coletada, mas em número baixo na escada, onde predominaram espécies sedentárias pequenas. As espécies mais abundantes foram as sedentárias Apareiodon affinis, Bryconamericus stramineus, Astyanax fasciatus e Parodon nasus. Observações feitas na janela da escada revelaram que os peixes realizavam movimentos ascendentes e descendentes. A escada de peixes é um microhabitat habitado por uma abundante associação de organismos bentônicos que é provavelmente usada como recurso alimentar pela ictiofauna na escada. A similaridade entre a ictiofauna no reservatório de Ourinhos e na escada é baixa (26%). A riqueza de espécies migradoras no trecho entre os reservatórios a montante (Chavantes) e a jusante (Salto Grande), antes do fechamento da barragem de Ourinhos (23 espécies) foi reduzida para 16 e 12 espécies, respectivamente em Salto Grande e Ourinhos, depois do fechamento da barragem, e a apenas uma espécie na escada Abstract in english The composition and abundance of the fish assemblage were evaluated in the fish ladder of Ourinhos Dam, the newest dam (closed in 2005) in the cascade of dams constructed on the Paranapanema River. Samplings were carried out three times on a diel cycle, in three sampling periods, two in the warm sea [...] son and one in the cold season of 2008 - 2009. The ladder was closed and emptied and the entire fish assemblage was sampled and identified. Most individuals were released alive downstream of the dam. The assemblage found in the ladder was compared with the fish fauna sampled in the reservoir and in downstream sites, in the same period. Twenty seven species and a total of 4682 individuals were caught in the ladder. Pimelodus maculatus was the only migratory species, which was caught in low number in the ladder (0.04% of the total captured), where small sedentary species predominated. The most abundant species were the non-migratory Apareiodon affinis, Bryconamericus stramineus, Astyanax fasciatus and Parodon nasus. Individuals observed in the ladder's window were moving up- and down the passage. The fish ladder is a microhabitat inhabited by an abundant association of benthic organisms that is probably used as a food resource for the fish assemblage in the ladder. The similarity between the fish fauna in the ladder and that of the Ourinhos Reservoir was low (26%). The species richness of migrants in the stretch between the uspstream reservoir (Chavantes) and the downstream one (Salto Grande), before the Ourinhos dam closure (23 species) was reduced to 16 and 12 species in Salto Grande and Ourinhos reservoirs, respectively, after the dam closure, and to a single species in the ladder.

  11. The fish fauna in the fish passage at the Ourinhos Dam, Paranapanema River

    Directory of Open Access Journals (Sweden)

    Marlene Sofia Arcifa

    2012-10-01

    Full Text Available The composition and abundance of the fish assemblage were evaluated in the fish ladder of Ourinhos Dam, the newest dam (closed in 2005 in the cascade of dams constructed on the Paranapanema River. Samplings were carried out three times on a diel cycle, in three sampling periods, two in the warm season and one in the cold season of 2008 - 2009. The ladder was closed and emptied and the entire fish assemblage was sampled and identified. Most individuals were released alive downstream of the dam. The assemblage found in the ladder was compared with the fish fauna sampled in the reservoir and in downstream sites, in the same period. Twenty seven species and a total of 4682 individuals were caught in the ladder. Pimelodus maculatus was the only migratory species, which was caught in low number in the ladder (0.04% of the total captured, where small sedentary species predominated. The most abundant species were the non-migratory Apareiodon affinis, Bryconamericus stramineus, Astyanax fasciatus and Parodon nasus. Individuals observed in the ladder's window were moving up- and down the passage. The fish ladder is a microhabitat inhabited by an abundant association of benthic organisms that is probably used as a food resource for the fish assemblage in the ladder. The similarity between the fish fauna in the ladder and that of the Ourinhos Reservoir was low (26%. The species richness of migrants in the stretch between the uspstream reservoir (Chavantes and the downstream one (Salto Grande, before the Ourinhos dam closure (23 species was reduced to 16 and 12 species in Salto Grande and Ourinhos reservoirs, respectively, after the dam closure, and to a single species in the ladder.A composição e abundância da ictiofauna da escada de peixes da barragem de Ourinhos, a mais nova hidrelétrica (fechada em 2005 na sequência de barragens construídas no rio Paranapanema, foram avaliadas três vezes em um ciclo diário, em três períodos de coleta, dois no verão e um no inverno de 2008-2009. A escada foi fechada e esvaziada e os peixes coletados e identificados, antes da devolução da maior parte deles a jusante. A ictiofauna da escada foi comparada à do reservatório de Ourinhos, coletada na mesma época. Vinte e sete espécies e 4862 indivíduos foram coletados na escada. Pimelodus maculatus foi a única espécie migradora coletada, mas em número baixo na escada, onde predominaram espécies sedentárias pequenas. As espécies mais abundantes foram as sedentárias Apareiodon affinis, Bryconamericus stramineus, Astyanax fasciatus e Parodon nasus. Observações feitas na janela da escada revelaram que os peixes realizavam movimentos ascendentes e descendentes. A escada de peixes é um microhabitat habitado por uma abundante associação de organismos bentônicos que é provavelmente usada como recurso alimentar pela ictiofauna na escada. A similaridade entre a ictiofauna no reservatório de Ourinhos e na escada é baixa (26%. A riqueza de espécies migradoras no trecho entre os reservatórios a montante (Chavantes e a jusante (Salto Grande, antes do fechamento da barragem de Ourinhos (23 espécies foi reduzida para 16 e 12 espécies, respectivamente em Salto Grande e Ourinhos, depois do fechamento da barragem, e a apenas uma espécie na escada

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

    Directory of Open Access Journals (Sweden)

    Yasser R. Abdel-Fattah

    2006-01-01

    Full Text Available 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 extension time, 72 sec. A verification of the predicted model revealed a 91.5% accuracy level.

  13. Fractal ladder models and power law wave equations.

    Science.gov (United States)

    Kelly, James F; McGough, Robert J

    2009-10-01

    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

  14. Design and characterization of self-assembled fish sarcoplasmic protein-alginate nanocomplexes

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; Mattebjerg, Maria Ahlm; Wattjes, Jasper; Milisavljevic, Ana; Jessen, Flemming; Qvortrup, Klaus; Goycoolea, Francisco M.; Chronakis, Ioannis S.

    2015-01-01

    Macrostructures based on natural polymers are subject to large attention, as the application range is wide within the food and pharmaceutical industries. In this study we present nanocomplexes (NCXs) made from electrostatic self-assembly between negatively charged alginate and positively charged fish sarcoplasmic proteins (FSP), prepared by bulk mixing. A concentration screening revealed that there was a range of alginate and FSP concentrations where stable NCXs with similar properties were form...

  15. Design and Control of an Embedded Vision Guided Robotic Fish with Multiple Control Surfaces

    OpenAIRE

    Junzhi Yu; Kai Wang; Min Tan; Jianwei Zhang

    2014-01-01

    This paper focuses on the development and control issues of a self-propelled robotic fish with multiple artificial control surfaces and an embedded vision system. By virtue of the hybrid propulsion capability in the body plus the caudal fin and the complementary maneuverability in accessory fins, a synthesized propulsion scheme including a caudal fin, a pair of pectoral fins, and a pelvic fin is proposed. To achieve flexible yet stable motions in aquatic environments, a central pattern genera...

  16. A Motor-less and Gear-less Bio-mimetic Robotic Fish Design

    OpenAIRE

    Rossi, Claudio; Coral Cuellar, William; Colorado Montaño, Julián; Barrientos Cruz, Antonio

    2011-01-01

    In this paper, we describe our current work on bio-inspired locomotion systems using a deformable structure and smart materials, concretely Shape Memory Alloys, exploring the possibility of building motor-less and gear-less robots. A swimming underwater robot has been developed whose movements are generated using such actuators, used for bending the backbone of the fish, which in turn causes a change on the curvature of the body. This paper focuses on how standard swimming patterns can be rep...

  17. Fine-Tuning of Magnetic Interactions in Organic Spin Ladders

    OpenAIRE

    Yamaguchi, Hironori; Miyagai, Hirotsugu; Shimokawa, Tokuro; Iwase, Kenji; Ono, Toshio; Kono, Yohei; Kase, Naoki; Araki, Koji; Kittaka, Shunichiro; Sakakibara, Toshiro; Kawakami, Takashi; Okunishi, Kouichi; Hosokoshi, Yuko

    2014-01-01

    We have succeeded in synthesizing two types of new organic radical crystals 3-I-V [= 3- (3-iodophenyl)-1,5-diphenylverdazyl] and 3-Br-4-F-V [= 3-(3-bromo-4-fluorophenyl)-1,5- diphenylverdazyl]. Their crystal strucutures are found to be isomorphous to that of previously reported spin ladder 3-Cl-4-F-V. Through the quantitative analysis of their molecular arrangements and magnetic properties, we confirm that these materials form ferromagnetic chain-based spin ladders with slig...

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

    LENUS (Irish Health Repository)

    Kennedy, Harry G

    2011-09-01

    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\

  19. Ladder operators and differential equations for multiple orthogonal polynomials

    International Nuclear Information System (INIS)

    In this paper, we obtain the ladder operators and associated compatibility conditions for types I and II multiple orthogonal polynomials. These ladder equations extend known results for orthogonal polynomials and can be used to derive the differential equations satisfied by multiple orthogonal polynomials. Our approach is based on Riemann–Hilbert problems and the Christoffel–Darboux formula for multiple orthogonal polynomials, and the nearest-neighbor recurrence relations. As an illustration, we give several explicit examples involving multiple Hermite and Laguerre polynomials, and multiple orthogonal polynomials with exponential weights and cubic potentials. (paper)

  20. Efficient infrared upconversion via a ladder-type atomic configuration

    CERN Document Server

    Ding, Dong-Sheng; Shi, Bao-Sen; Zou, Xu-Bo; Guo, Guang-Can

    2012-01-01

    We experimentally demonstrate an infrared light at 1529.4nm can be converted into the visible at 780nm with 54% efficiency through a ladder-type atomic configuration in Rb85. In particular, theoretically, we analyze the high efficiency is due to the large nonlinear dispersion of the index of refraction from the off-resonant enhancement in four-wave mixing process. The high efficiency using a ladder-type configuration in hot Rb85 atoms is an important advance in nonlinear optics and quantum information fields.

  1. Notebook Positioning by Perceptual Map and Laddering Method

    Directory of Open Access Journals (Sweden)

    Mehdi Zaribaf

    2012-01-01

    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.

  2. Combining a clinical ladder and performance appraisal system as a reward strategy: the EXCEL clinical ladder program.

    Science.gov (United States)

    Moe, J K; Lonowski, L R; Yancer, D A

    1994-09-01

    In response to the dramatic changes occurring in health care today and a desire to reward professional nurses for clinical behaviors that would be valued in the future, Bergan Mercy Medical Center (BMMC) has developed an innovative clinical ladder/performance appraisal system. The BMMC EXCEL Clinical Ladder program, which is based on the developmental model of Patricia Benner, is a competency-based system that uniquely combines a clinical ladder and performance appraisal system. The program is clinically focused and contains optional components in which registered nurses (RNs) can receive additional credit for participation in professional growth and leadership activities. Nurses document examples of their practice through nursing narratives that describe actual clinical situations. The development and implementation processes, challenges encountered, and recommendations for alternative approaches to the implementation of such a unique system are discussed. PMID:7922675

  3. 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 ( ... medical alert bracelet. Continue What Happens in a Fish Allergy When someone is allergic to fish, the ...

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

    Directory of Open Access Journals (Sweden)

    T.Chalama Reddy

    2013-06-01

    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.

  5. Schroedinger operators with the q-ladder symmetry algebras

    Science.gov (United States)

    Skorik, Sergei; Spiridonov, Vyacheslav

    1994-01-01

    A class of the one-dimensional Schroedinger operators L with the symmetry algebra LB(+/-) = q(+/-2)B(+/-)L, (B(+),B(-)) = P(sub N)(L), is described. Here B(+/-) are the 'q-ladder' operators and P(sub N)(L) is a polynomial of the order N. Peculiarities of the coherent states of this algebra are briefly discussed.

  6. Single-particle potential from resummed ladder diagrams

    CERN Document Server

    Kaiser, Norbert

    2013-01-01

    A recent work on the resummation of fermionic in-medium ladder diagrams to all orders is extended by calculating the single-particle potential $U(p,k_f)$ for hole-states with $pk_f$ is also considered.

  7. Ladder operators for solvable potentials connected with exceptional orthogonal polynomials

    Science.gov (United States)

    Quesne, C.

    2015-04-01

    Exceptional orthogonal polynomials constitute the main part of the bound-state wavefunctions of some solvable quantum potentials, which are rational extensions of well-known shape-invariant ones. The former potentials are most easily built from the latter by using higher-order supersymmetric quantum mechanics (SUSYQM) or Darboux method. They may in general belong to three different types (or a mixture of them): types I and II, which are strictly isospectral, and type III, for which k extra bound states are created below the starting potential spectrum. A well-known SUSYQM method enables one to construct ladder operators for the extended potentials by combining the supercharges with the ladder operators of the starting potential. The resulting ladder operators close a polynomial Heisenberg algebra (PHA) with the corresponding Hamiltonian. In the special case of type III extended potentials, for this PHA the k extra bound states form k singlets isolated from the higher excited states. Some alternative constructions of ladder operators are reviewed. Among them, there is one that combines the state-adding and state-deleting approaches to type III extended potentials (or so-called Darboux-Crum and Krein-Adler transformations) and mixes the k extra bound states with the higher excited states. This novel approach can be used for building integrals of motion for two-dimensional superintegrable systems constructed from rationally-extended potentials.

  8. Antiferromagnetic Ising model saturation field entropies: ladders and kagome lattice

    CERN Document Server

    Varma, Vipin Kerala

    2013-01-01

    Saturation field entropies of antiferromagnetic Ising models on quasi one-dimensional lattices (ladders) and the kagome lattice are calculated. The former is evaluated exactly by constructing the corresponding transfer matrices, while the latter calculation uses Binder's algorithm for efficiently and exactly computing the partition function of over 1300 spins to give S/k_B = 0.393589(6).

  9. Sequencing DNA using mass spectrometry for ladder detection.

    OpenAIRE

    Taranenko, N I; Allman, S. L.; Golovlev, V V; Taranenko, N V; Isola, N R; Chen, C. H.

    1998-01-01

    Sequencing of DNA fragments of 130 and 200 bp using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for DNA ladder detection was demonstrated. With further improvement in mass resolution and detection sensitivity, mass spectrometry shows great promise for routine DNA sequencing in the future.

  10. 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.)

  11. Dynamics of a Sliding Ladder Leaning against a Wall

    Science.gov (United States)

    Oliveira, J. B.; Simeão Carvalho, P.; Mota, M. F.; Quintas, M. J.

    2015-01-01

    This study is about the dynamics of a sliding ladder leaning against a vertical wall. The results are understood by considering the motion divided in two parts: (i) for 0 = t = t[subscript s] with one degree of freedom, and (ii) for t > t[subscript s] with two degrees of freedom, where the separation is determined by the instance t[subscript…

  12. Ladder Theorem for a Leray alpha model of turbulence

    OpenAIRE

    Ali, Hani

    2009-01-01

    In this paper, we study the Modified Leray alpha model with periodic boundary conditions. We show that when the initial data are infinitely differentiable then the unique solution are infinitely differentiable in space and time. Furthermore, this regular solution verifies a sequence of energy inequalities that is called "ladder inequalities".

  13. Towards flavored bound states beyond rainbows and ladders

    Energy Technology Data Exchange (ETDEWEB)

    El-Bennich, B.; Rojas, E.; Melo, J. P. B. C. de [Laboratório de Física Teórica e Computacional, Universidade Cruzeiro do Sul, São Paulo 01506-000 SP (Brazil); Paracha, M. A. [Laboratorio de Fisica Teorica e Computacional, Universidade Cruzeiro do Sul, Sao Paulo 01506-000 SP, Brazil and Centre for Advanced Mathematics and Physics, National University of Science and Technology, Islamabad (Pakistan)

    2014-11-11

    We give a snapshot of recent progress in solving the Dyson-Schwinger equation with a beyond rainbow-ladder ansatz for the dressed quark-gluon vertex which includes ghost contributions. We discuss the motivations for this approach with regard to heavy-flavored bound states and form factors and briefly describe future steps to be taken.

  14. Nonperturbative Study of Generalized Ladder Graphs in a var-phi 2? Theory

    International Nuclear Information System (INIS)

    The Feynman-Schwinger representation is used to construct scalar-scalar bound states for the set of all ladder and crossed-ladder graphs in a var-phi 2? theory in 3+1 dimensions. The results are compared to those of the usual Bethe-Salpeter equation in the ladder approximation and of several quasipotential equations. Particularly for large couplings, the ladder predictions are seen to underestimate the binding energy significantly as compared to the generalized ladder case, whereas the solutions of the quasipotential equations provide a better correspondence. Results for the calculated bound state wave functions are also presented. copyright 1996 The American Physical Society

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

    International Nuclear Information System (INIS)

    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.

  16. Nonperturbative study of generalized ladder graphs in a $\\phi^{2}\\chi$ theory

    CERN Document Server

    Nieuwenhuis, T; Nieuwenhuis, Taco

    1996-01-01

    The Feynman-Schwinger representation is used to construct scalar-scalar bound states for the set of all ladder and crossed-ladder graphs in a \\phi^2\\chi theory in (3+1) dimensions. The results are compared to those of the usual Bethe-Salpeter equation in the ladder approximation and of several quasi-potential equations. Particularly for large couplings, the ladder predictions are seen to underestimate the binding energy significantly as compared to the generalized ladder case, whereas the solutions of the quasi-potential equations provide a better correspondence. Results for the calculated bound state wave functions are also presented.

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  18. The Effects of Laddering and Spinning in Underwriter Manipulation of IPOs

    Directory of Open Access Journals (Sweden)

    Ludwig Chincarini

    2012-09-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Ayca Kangal

    2013-04-01

    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.

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

    International Nuclear Information System (INIS)

    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.

  1. Design and characterization of self-assembled fish sarcoplasmic protein-alginate nanocomplexes.

    Science.gov (United States)

    Stephansen, Karen; Mattebjerg, Maria; Wattjes, Jasper; Milisavljevic, Ana; Jessen, Flemming; Qvortrup, Klaus; Goycoolea, Francisco M; Chronakis, Ioannis S

    2015-05-01

    Macrostructures based on natural polymers are subject to large attention, as the application range is wide within the food and pharmaceutical industries. In this study we present nanocomplexes (NCXs) made from electrostatic self-assembly between negatively charged alginate and positively charged fish sarcoplasmic proteins (FSP), prepared by bulk mixing. A concentration screening revealed that there was a range of alginate and FSP concentrations where stable NCXs with similar properties were formed, rather than two exact concentrations. The size of the NCXs was 293 ± 3 nm, and the zeta potential was -42 ± 0.3 mV. The NCXs were stable in water, gastric buffer, intestinal buffer and HEPES buffered glycose, and at all pH values from 2 to 9 except pH 3, where they aggregated. When proteolytic enzymes were present in the buffer, the NCXs were degraded. Only at high concentrations the NCXs caused a decreased viability in HeLa and U2OS cell lines. The simple processing procedure and the high stability of the NCXs, makes them excellent candidates for use in the food and pharmaceutical industry. PMID:25709012

  2. Design and characterization of self-assembled fish sarcoplasmic protein-alginate nanocomplexes

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; Mattebjerg, Maria Ahlm

    2015-01-01

    Macrostructures based on natural polymers are subject to large attention, as the application range is wide within the food and pharmaceutical industries. In this study we present nanocomplexes (NCXs) made from electrostatic self-assembly between negatively charged alginate and positively charged fish sarcoplasmic proteins (FSP), prepared by bulk mixing. A concentration screening revealed that there was a range of alginate and FSP concentrations where stable NCXs with similar properties were formed, rather than two exact concentrations. The size of the NCXs was 293 +/- 3 nm, and the zeta potential was -42 +/- 0.3 mV. The NCXs were stable in water, gastric buffer, intestinal buffer and HEPES buffered glycose, and at all pH values from 2 to 9 except pH 3, where they aggregated. When proteolytic enzymes were present in the buffer, the NCXs were degraded. Only at high concentrations the NCXs caused a decreased viability in HeLa and U2OS cell lines. The simple processing procedure and the high stability of the NCXs, makes them excellent candidates for use in the food and pharmaceutical industry. (C) 2015 Elsevier B.V. All rights reserved.

  3. The resonance self-shielding calculation with regularized random ladders

    International Nuclear Information System (INIS)

    The straightforward method for calculation of resonance self-shielding is to generate one or several resonance ladders, and to process them as resolved resonances. The main drawback of Monte Carlo methods used to generate the ladders, is the difficulty of reducing the dispersion of data and results. Several methods are examined, and it is shown how one (a regularized sampling method) improves the accuracy. Analytical methods to compute the effective cross-section have recently appeared: they are basically exempt from dispersion, but are inevitably approximate. The accuracy of the most sophisticated one is checked. There is a neutron energy range which is improperly considered as statistical. An examination is presented of what happens when it is treated as statistical, and how it is possible to improve the accuracy of calculations in this range. To illustrate the results calculations have been performed in a simple case: nucleus 238U, at 300 K, between 4250 and 4750 eV. (author)

  4. Bethe–Salpeter studies of mesons beyond rainbow-ladder

    Directory of Open Access Journals (Sweden)

    Williams R.

    2010-04-01

    Full Text Available We investigate the masses of light mesons from a coupled system of Dyson–Schwinger and Bethe– Salpeter equations. We explicitly take into account dominant non-Abelian and sub-leading Abelian contributions to the dressed quark-gluon vertex. We also include unquenching e?ects in the form of hadronic resonance contributions via the back-reaction of pions. We construct the corresponding Bethe–Salpeter kernel that satis?es the axial-vector Ward-Takahashi identity. Our numerical treatment fully includes all momentum dependencies with all equations solved completely in the complex plane. This approach goes well beyond the rainbow-ladder approximation and permits us to investigate the relative impact of di?erent corrections beyond rainbow-ladder on the properties of mesons. We ?nd that sub-leading Abelian corrections are further dynamically suppressed, and that our results supersede early qualitative predictions with signi?cantly simpler truncation schemes.

  5. Phase sensitive quantum interference on forbidden transition in ladder scheme

    OpenAIRE

    Koganov, Gennady A.; Shuker, Reuben

    2014-01-01

    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 characteristic...

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

    Scientific Electronic Library Online (English)

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

    2011-06-01

    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.

  7. 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)

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

    Directory of Open Access Journals (Sweden)

    Bruno Bordeaux-Rego

    2011-04-01

    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.

  9. Up and Down the Communications Ladder

    Science.gov (United States)

    Harriman, Bruce

    1974-01-01

    Describes the steps one company took when it found it had serious difficulties. Discusses "up-and-down" theory of communications, which the company used to design its own "upward communications program." Describes each part of the program, explaining how it was set up, what stumbling blocks were encountered, and what successes were experienced.…

  10. 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.

  11. 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)

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

    2007-01-01

    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.

  12. Magnetization transport in spin ladders and next-nearest-neighbor chains

    OpenAIRE

    Znidaric, Marko

    2013-01-01

    We study magnetization transport at high temperatures in several spin ladder systems as well as in next-nearest-neighbor coupled spin chains. In the integrable ladder considered we analytically show that the transport is ballistic in sectors with nonzero average magnetization, while numerical simulations of a nonequilibrium stationary setting indicate an anomalous transport in the zero magnetization (half-filling) sector. For other systems, isotropic Heisenberg ladder and sp...

  13. Development of ultra-light pixelated ladders for an ILC vertex detector

    CERN Document Server

    Chon-Sen, N; Claus, G; De Masi, R; Deveaux, M; Dulinski, W; Goffe, M; Goldstein, J; Gregor, I -M; Imhoff, Ch Hu-Guo M; Müntz, C; Nomerotski, A; Santos, C; Schrader, C; Specht, M; Stroth, J; Winter, M

    2010-01-01

    The development of ultra-light pixelated ladders is motivated by the requirements of the ILD vertex detector at ILC. This paper summarizes three projects related to system integration. The PLUME project tackles the issue of assembling double-sided ladders. The SERWIETE project deals with a more innovative concept and consists in making single-sided unsupported ladders embedded in an extra thin plastic enveloppe. AIDA, the last project, aims at building a framework reproducing the experimental running conditions where sets of ladders could be tested.

  14. EFFECT OF FISH AQUACULTURE ON WATER QUALITY IN RESTORED, HISTORICAL FISH PONDS ON MOLOKAI ISLAND, HAWAII

    Science.gov (United States)

    The Molokoi Fish Pond Project is designed to determine effects on water quality of commercial fish production within several different historical fish ponds and immediately offshore in order to establish appropriate water quality standards and discharge permit conditions for the ...

  15. Ladder operators and coherent states for nonlinear potentials

    Energy Technology Data Exchange (ETDEWEB)

    Roman-Ancheyta, R; De los Santos-Sanchez, O; Recamier, J [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apdo. Postal 48-3, Cuernavaca, Morelos 62251 (Mexico)

    2011-10-28

    In this work, we make use of deformed operators to construct the coherent states of some nonlinear systems by generalization of two definitions: (i) as eigenstates of a deformed annihilation operator and (ii) by application of a deformed displacement operator to the vacuum state. We also construct the coherent states for the same systems using the ladder operators obtained by traditional methods with the knowledge of the eigenfunctions and eigenvalues of the corresponding Schroedinger equation. We show that both methods yield coherent states with identical algebraic structure. (paper)

  16. Ladder operators and recursion relations for the associated Bessel polynomials

    International Nuclear Information System (INIS)

    Introducing the associated Bessel polynomials in terms of two non-negative integers, and under an integrability condition we simultaneously factorize their corresponding differential equation into a product of the ladder operators by four different ways as shape invariance symmetry equations. This procedure gives four different pairs of recursion relations on the associated Bessel polynomials. In spite of description of Bessel and Laguerre polynomials in terms of each other, we show that the associated Bessel differential equation is factorized in four different ways whereas for Laguerre one we have three different ways

  17. Diverging thermal conductivity of spin-chains and ladders

    CERN Document Server

    Alvarez, J V; Gros, Claudius

    2002-01-01

    We study the thermal transport properties of quantum spin chains and ladders. We find a diverging thermal conductivity at finite temperatures, independent of microscopic details of the models. The temperature at which the non-diverging prefactor kappa^{(th)}(T) peaks is in general substantially lower than the temperature at which the corresponding specific heat c_V(T) is maximal. We show that this effect has far-reaching consequences for the magnetic mean-free path lambda extracted by analyzing recent experiments with the microscopic theory results.

  18. Period halving of Persistent Currents in Mesoscopic Mobius ladders

    CERN Document Server

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

    2002-01-01

    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}

  19. 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

  20. Optical coherences and wavelength mismatch in ladder systems

    CERN Document Server

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

    2013-01-01

    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.

  1. Inverse magnetocaloric effects in two-leg spin ladder system

    International Nuclear Information System (INIS)

    Magnetocaloric properties of the two-leg frustrated spin ladder system are investigated by the use of transfer-matrix method. Exact results for the magnetization, entropy, entropy change and magnetocaloric cooling rate versus temperature and field are presented and discussed in detail. Large inverse magnetocaloric effects induced by the field arise at low temperature, and exhibit strong dependency relationship on the exchange couplings. In the vicinity of the critical field, the enhanced inverse magnetocaloric effects and normal magnetocaloric effects are both observed. Besides, the influences of the single-ion anisotropy on the entropy change are discussed as well.

  2. Beyond rainbow-ladder in bound state equations

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-15

    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.)

  3. Fish tapeworm

    Science.gov (United States)

    Fish tapeworm is an infection with a parasite found in fish. ... The fish tapeworm ( Diphyllobothrium latum ), is the largest parasite that infects humans. Humans become infected when they eat raw ...

  4. Vitamin content of fish and fish products consumed in Portugal

    OpenAIRE

    Dias, M.Graça; M.V. Sánchez; Bártolo, H; Oliveira, Luísa

    2003-01-01

    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....

  5. Reported Job Interest and Perceived Utilization of Talents and Training by Airmen in 97 Career Ladders.

    Science.gov (United States)

    Gould, R. Bruce

    As part of the United States Air Force Occupational Survey Program, this report summarizes the results of a study conducted to determine the dimensions of job satisfaction within and between career ladders as perceived by airmen. Surveyed on 97 career ladders were some 100,000 respondents. Findings include: (1) Most of the airmen surveyed found…

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

    Science.gov (United States)

    Ucak, C.

    2009-01-01

    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…

  7. Non-perturbative renormalization group analysis of dynamical chiral symmetry breaking with beyon ladder contributions

    Energy Technology Data Exchange (ETDEWEB)

    Tomoyose, M. [Kanazawa University, Institute for Theoretical Physics, Kanazawa, Ishikawa (Japan)

    2001-07-01

    The order parameters of dynamical chiral symmetry breaking in QCD are evaluated by solving the non-perturbative renormalization group (NPRG) equations. We employ an approximation scheme beyond the ladder approximation. The chiral condensates are enhanced in comparison with the ladder approximation. The gauge dependence of the order parameters is reduced significantly in this scheme. (author)

  8. Bio-inspired particle separator design based on the food retention mechanism by suspension-feeding fish.

    Science.gov (United States)

    Hung, Tien-Chieh; Piedrahita, Raul H; Cheer, Angela

    2012-12-01

    A new particle separator is designed using a crossflow filtration mechanism inspired by suspension-feeding fish in this study. To construct the model of the bio-inspired particle separator, computational fluid dynamics techniques are used, and parameters related to separator shape, fluid flow and particle properties that might affect the performance in removing particles from the flow, are varied and tested. The goal is to induce a flow rotation which enhances the separation of particles from the flow, reduce the particle-laden flow that exits via a collection zone at the lower/posterior end of the separator, while at the same time increase the concentration of particles in that flow. Based on preliminary particle removal efficiency tests, an exiting flow through the collection zone of about 8% of the influent flow rate is selected for all the performance tests of the separator including trials with particles carried by air flow instead of water. Under this condition, the simulation results yield similar particle removal efficiencies in water and air but with different particle properties. Particle removal efficiencies (percentage of influent particles that exit through the collection zone) were determined for particles ranging in size from 1 to 1500 µm with a density between 1000 and 1150 kg m(-3) in water and 2 and 19 mm and 68 and 2150 kg m(-3) in air. As an example, removal efficiencies are 66% and 64% for 707 µm diameter particles with a density of 1040 kg m(-3) in water and for 2 mm particles with a density of 68 kg m(-3) in air, respectively. No significant performance difference is found by geometrically scaling the inlet diameter of the separator up or down in the range from 2.5 to 10 cm. PMID:22820145

  9. Bio-inspired particle separator design based on the food retention mechanism by suspension-feeding fish

    International Nuclear Information System (INIS)

    A new particle separator is designed using a crossflow filtration mechanism inspired by suspension-feeding fish in this study. To construct the model of the bio-inspired particle separator, computational fluid dynamics techniques are used, and parameters related to?separator shape, fluid flow and particle properties that might affect the performance in removing particles from the flow, are varied and tested. The goal is to induce a flow rotation which enhances the separation of particles from the flow, reduce the particle-laden flow that exits via a collection zone at the lower/posterior end of the separator, while at the same time increase the concentration of particles in that flow. Based on preliminary particle removal efficiency tests, an exiting flow through the collection zone of about 8% of the influent flow rate is selected for all the performance tests of the separator including trials with particles carried by air flow instead of water. Under this condition, the simulation results yield similar particle removal efficiencies in water and air but with different particle properties. Particle removal efficiencies (percentage of influent particles that exit through the collection zone) were determined for particles ranging in size from 1 to 1500 µm with a density between 1000 and 1150 kg m?3 in water and 2 and 19 mm and 68 and 2150 kg m?3 in air. As an example, removal efficiencies are 66% and 64% for 707 µm diameter particles with a density of 1040 kg?m?3 in water and for 2 mm particles with a density of 68 kg m?3 in air, respectively. No significant performance difference is found by geometrically scaling the inlet diameter of the separator up or down in the range from 2.5 to 10 cm. (paper)

  10. A Phenylene-alkylated Thiophene-based Partially Ladder-type Conjugated Polymer

    International Nuclear Information System (INIS)

    A partially ladder-type polymer was synthesized, where the ladder-type planar structure was prepared using BBr3-promoted cyclization and alkylated thiophene was used as a soluble derivative. The relatively small band gap and broad absorption band, in addition to the crystallinity, make this polymer an attractive material for use in a variety of optoelectronic applications. The rigid coplanar structures of such polymers provide resistance to deformation and enhanced ?-conjugation, which result in a number of desirable properties, such as intense luminescence, high carrier mobility, and environmental stability. Most studies in this field have focused on poly(p-phenylene)-based polymers, including both step ladder-type or fully ladder-type poly(phenylene)s. However, the commercial exploitation of ladder poly(phenylene) homopolymers has been hampered by their intractable nature

  11. QMC Study of the three-chain Hubbard ladder

    Science.gov (United States)

    Evertz, H. G.; Faber, Chr.; Hanke, W.

    1996-03-01

    Ladder systems permit the study of dimensional crossover from 1 to 2 dimensions. In the Heisenberg model one expects that ladders with an even number of legs show a spin-gap, whereas those with an odd number are gapless. This has been verified experimentally in compounds like Sr_nCu_n+1O_2n+1 and La_1-xSrx Cu O_2.5 (Z. Hiroi and M. Takano, Nature 377), 41 (1995); ^2 M. Frischmuth et al., in preparation; ^3 E. Arrigoni, cond-mat/9509145; ^4 H.G. Evertz, G. Lana, M. Marcu, PRL 70, 875 (1993); N. Kawashima, J.E. Gubernatis, H.G. Evertz, PRB 50, 136 (1994). and theoretically, e.g. by QMC simulations ^2. For the Hubbard model the situation is more complicated. Weak coupling (small U) renormalization group ^3 for the three-leg system shows a rich phase diagram. At half filling, three phases are predicted as the coupling t_? between the chains is changed: insulating spin-gapped, metal gapless, and insulating gapped. For the doped system, a large number of further phases appear, e.g. a fermi liquid at isotropic couplings. We performed QMC studies using both determinantal methods and the very efficient loop-algorithm ^4 in the worldline formalism. We report results on the phase diagram and on pairing properties for different couplings and temperatures.

  12. Slow magnetic relaxation in lanthanide ladder type coordination polymers.

    Science.gov (United States)

    Girginova, Penka I; Pereira, Laura C J; Coutinho, Joana T; Santos, Isabel C; Almeida, Manuel

    2014-01-28

    A series of four isostructural lanthanide-containing one dimensional coordination polymers with picolinic (pic) and glutaric (glu) acids, Ln(glu)(pic)(H2O)2, where Ln = Gd(III) (1), Tb(III) (2), Dy(III) (3) and Er(III) (4) were synthesized under hydrothermal conditions and structurally characterized by powder and single-crystal X-ray diffraction, elemental analysis, IR spectroscopy and thermogravimetric measurements. These compounds are isostructural to the previously reported Sm(glu)(pic)(H2O)2 and the structure consists in pairs of lanthanide ions double bridged by carboxylic groups which are connected along c by the glutaric acid ligands as a ladder type 1D coordination polymer. The magnetic properties of these compounds were studied by static magnetization and AC magnetic susceptibility measurements in the temperature range 1.7-300 K. Weak dominant ferromagnetic interactions between lanthanide cations were found in the compounds, except in compound 3. Compounds 1, 3 and 4 reveal frequency dependent AC susceptibility and slow relaxation of the magnetization under applied external static field. These data classify the Gd(III), Dy(III) and Er(III) compounds as molecular magnets. In spite of the ladder chain structure of the compounds this magnetic behaviour is not due to a single chain but instead it is ascribed to single ion anisotropic effects in the case of 3 and 4 and possibly to a phonon-bottleneck effect of the spin-lattice relaxation in 1. PMID:24264729

  13. FishWatch

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — FishWatch is designed to help you make informed decisions about the seafood you eat. It can also help you understand the management and science requirements...

  14. Multicriteria assessment in restoring migratory fish stocks in the river Iijoki; Monitavoitearviointi Iijoen vaelluskalakantojen palauttamisen tukena

    Energy Technology Data Exchange (ETDEWEB)

    Karjalainen, T.P.; Rytkoenen, A.-M.; Marttunen, M.; Maeki-Petaeys, A.; Autti, O.

    2011-05-15

    The Iijoki is one of Finland's most important former salmon rivers. Construction of multiple main stem dams on the river in the 1960s effectively blocked the migration corridors of migratory fish. Suitable spawning and nursery habitats above the dams span an estimated 600-800 hectares. With riverside residents are very much in favour of the return of migratory fish, watershed planning for this has been set as a target. Such measures are rendered urgent by the fact that there is still a possibility of replenishing the Iijoki's own salmon stock, thereby restoring the fishes' natural lifecycle and natural selection. This report has been completed as part of the project 'The return of migratory fish to the River Iijoki (2008-2010)', where the main object was reconciling the target of enhancing the natural life cycle of migratory fish with the continued generation of hydropower. Under a multicriteria assessment, various alternatives and measures for improving migratory fish stocks were clarified and their desirability, costs and benefits systematically and transparently evaluated. Furthermore, interest groups' views of the three options and their effects (as distinct from the expert evaluation) were clarified with the help of computer aided interviews. The alternatives were transferring salmon above the main stem dams and two fish-ladder options. The multicriteria assessment viewed the construction of fish ladders, alongside other large-scale support measures, as the best option. Based on all of the criteria applied in a cost-benefit analysis, the stock transfer alternative was the most economically viable, because its net product value was positive in all cases. The fish ladder options were the most expensive due to the construction costs involved, but they also provided the greatest benefits. Above all, fish ladder construction is supported by the fact that it would return migratory fish to their natural lifecycle and attain the EU's watershed planning objectives. In addition, its effects on local identity, fishing tourism and the attractiveness of the area speak in its favour. With respect to the return of migratory fish, the greatest uncertainties lie in developments in the state of the Baltic Sea and the regulation of fishing. A multicriteria assessment helped the respondents and stakeholders achieve a better overall understanding of the planning situation and the various parties' objectives and views. This assisted in creating common ground in building a co-management model to establish further measures for the return of migrant fish. (orig.)

  15. The tunable quantum spin ladder Cu(Qnx)(Cl(1?x)Brx)2

    International Nuclear Information System (INIS)

    We report magnetic, specific heat and ESR measurements on a series of S=1/2 spin ladder compounds Cu(Qnx)(Cl(1?x)Brx)2. Down to T=2 K all the observables can be described by the spin ladder model with about 1% of S=1/2 impurities in the background, which are present even in a nominally pure Cu(Qnx)Cl2 and Cu(Qnx)Br2, for the whole range of 0?x?1. We extract ladder exchange constants Jl(x) and Jr(x) as well as the gap value ?(x) by comparing the experimental data to quantum Monte-Carlo simulations. As the ESR measurements show the g-factor of impurities to be precisely equal to g-factor of the ladder spins, we suppose the impurities to be the consequence of structural defects resulting in broken ladder ends. - Highlights: • A family of isostructural spin-ladder compounds was investigated. • A variation in exchange parameters with the degree of chemical substitution was found. • A small amount of paramagnetic spins was attributed to structural defects in a ladder

  16. Helical quantum Hall edge modes in bilayer graphene: a realization of quantum spin-ladders

    Science.gov (United States)

    Mazo, Victoria; Shimshoni, Efrat; Huang, Chia-Wei; Carr, Sam T.; Fertig, H. A.

    2015-10-01

    The rich phase diagram of quantum spin-ladder systems has attracted much attention in the theoretical literature. The progress in experimental realizations of this fascinating physics however has been much slower. While materials with a ladder-like structure exist, one always has coupling between the ladders to muddy the waters. In addition, such materials exhibit limited (if any) tunability in terms of the magnetic exchange parameters, and experimental probing of the different phases is a great challenge. In this work, we show that a realization of spin-ladder physics can occur in an engineered nanostructure made out of bilayer graphene in the ? =0 quantum Hall state. Specifically, we describe a split-double-gated setup in which a domain wall (DW) is explicitly induced in the middle of the sample, and show that an effective spin-ladder forms along this DW. The interaction strengths of the ladder are tunable by adjusting magnetic and electric fields as well as the spacing between the gates. Furthermore, we demonstrate that the effective spin ladder has a helical nature, meaning that the spin-correlations may be probed rather simply with charge transport experiments. We describe the phase diagram of this system, and show that certain transport measurements are very sensitive to the phase.

  17. Renormalized ladder-type expansions for many-particle propagators

    International Nuclear Information System (INIS)

    For a system of indistinguishable fermions with pairwise interactions, we consider renormalized, perturbative expansions for the three- and four-particle propagators (Green's functions) in terms of exact one-particle propagators, along with a pair interaction that may be bare (as it appears in the Hamiltonian) or dressed (polarized). Care is taken to provide a rigorous foundation for the diagrammatic representations of these perturbation series; in particular, it is demonstrated how each topologically distinct diagram represents an embedding (in three-dimensional space) of numerous separate terms in the perturbation series. Within a renormalized ladder approximation for the three- and four-particle propagators, we derive diagram weights (which differ from the two-particle diagram weights) in order to limit the perturbation series to topologically distinct, permutationally independent diagrams. These results lay the foundation for perturbative approximations that decouple the propagator and density matrix equations of motion

  18. Staggered parity-time-symmetric ladders with cubic nonlinearity.

    Science.gov (United States)

    D'Ambroise, Jennie; Kevrekidis, P G; Malomed, Boris A

    2015-03-01

    We introduce a ladder-shaped chain with each rung carrying a parity-time- (PT-) symmetric gain-loss dimer. The polarity of the dimers is staggered along the chain, meaning alternation of gain-loss and loss-gain rungs. This structure, which can be implemented as an optical waveguide array, is the simplest one which renders the system PT-symmetric in both horizontal and vertical directions. The system is governed by a pair of linearly coupled discrete nonlinear Schrödinger equations with self-focusing or defocusing cubic onsite nonlinearity. Starting from the analytically tractable anticontinuum limit of uncoupled rungs and using the Newton's method for continuation of the solutions with the increase of the inter-rung coupling, we construct families of PT-symmetric discrete solitons and identify their stability regions. Waveforms stemming from a single excited rung and double ones are identified. Dynamics of unstable solitons is investigated too. PMID:25871238

  19. The onset of superfluidity of hardcore bosons in disordered ladders

    Science.gov (United States)

    Carrasquilla, Juan; Becca, Federico; Fabrizio, Michele

    2011-03-01

    The effect of disorder on the zero-temperature phase diagram of a two-leg ladder of hardcore bosons is investigated using quantum Monte Carlo simulations. We first review some aspects of the clean system which are relevant for the understanding of the disordered case. In the disordered case, an intervening Bose-glass phase between the frozen Mott insulator with zero (or one) bosons per site and the superfluid phase is found. We also investigate the effect of disorder exactly at half filling, where for small values of disorder, there is a commensurate phase with a gap to all excitations, which is eventually destroyed for larger values of disorder. We argue that this phase is always surrounded by the so-called Bose glass and a direct transition from the superfluid is found only in the clean system. Finally, a phase diagram based on our numerical evidence is suggested.

  20. Consumers' perceptions of African wildlife meat : A laddering study

    DEFF Research Database (Denmark)

    Radder, Laetitia; Grunert, Klaus G.

    2009-01-01

    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.

  1. Phase diagram of the frustrated two-leg ladder model

    Science.gov (United States)

    Hakobyan, T.; Hetherington, J. H.; Roger, M.

    2001-04-01

    Using density-matrix renormalization group calculations, we investigate the general phase diagram of the frustrated two-leg ladder with Heisenberg interactions along legs, rungs, and diagonals. We confirm that all antiferromagnetic gapped states belong to the same universality class as the Haldane phase. In a three-dimensional phase diagram, we determine a continuous surface with singularities in the string-order parameter or its first derivative, corresponding to a transition between two Haldane phases with different topological order. Some parts of this transition surface are critical with zero gap and vanishing string-order parameter. In the complementary parts, the transition is first order with finite gap and string order. The boundary of this surface with the ferromagnetic region is a critical end line, when the surface is critical, and a triple line anywhere else. Part of this boundary coincides with the exactly soluble model proposed by Dmitriev, Krivnov, and Ovchinnikov [Phys. Rev. B 56, 5985 (1997)].

  2. Nuclear Spin Relaxation in Hole Doped Two-Leg Ladders

    CERN Document Server

    Fujiyama, S; Motoyama, N; Eisaki, H; Uchida, S I

    2000-01-01

    The nuclear spin-lattice relaxation rate ($1/T_{1}$) has been measured in the single crystals of hole doped two-leg ladder compounds Sr$_{14-x}$Ca$_{x}$Cu$_{24}$O$_{41}$ and in the undoped parent material La$_6$Ca$_8$Cu$_{24}$O$_{41}$. Comparison of $1/T_{1}$ at the Cu and the two distinct oxygen sites revealed that the major spectral weight of low frequency spin fluctuations is located near $q \\sim (\\pi, \\pi)$ for most of the temperature and doping ranges investigated. Remarkable difference in the temperature dependence of $1/T_1$ for the two oxygen sites in the heavily doped $x$=12 sample revealed reduction of singlet correlations between two legs in place of growing antiferromagnetic correlations along the leg direction with increasing temperature. Such behavior is most likely caused by the dissociation of bound hole pairs.

  3. Phase sensitive quantum interference on forbidden transition in ladder scheme

    CERN Document Server

    Koganov, Gennady A

    2014-01-01

    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...

  4. Quasiparticle collapsing in an anisotropic t-J ladder

    Science.gov (United States)

    Zhu, Zheng; Weng, Zheng-Yu

    2015-03-01

    Quasiparticle collapsing is a central issue in the study of strongly correlated electron systems. In the one-dimensional case, the quasiparticle collapsing in a form of spin-charge separation has been well established, but the problem remains elusive in dimensions higher than one. By using density matrix renormalization group (DMRG) algorithm, we show that in an anisotropic two-leg t- J ladder, an injected single hole behaves like a well-defined quasiparticle in the strong rung limit, but undergoes a ``phase transition'' with the effective mass diverging at a critical point towards the isotropic limit. After the transition, the quasiparticle collapses into a composite object of a self-localized charge (holon) and a deconfined spin-1/2 (spinon), accompanied by a substantially enhanced binding energy between two holes. We discuss the underlying novel mechanism, which is generic for a bipartite lattice of any dimensions.

  5. Measuring subjective meaning structures by the laddering method: Theoretical considerations and methodological problems

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Grunert, Suzanne C.

    1995-01-01

    Starting from a general model of measuring cognitive structures for predicting consumer behaviour, we discuss laddering as a possible method to obtain estimates of consumption-relevant cognitive structures which will have predictive validity. Four criteria for valid measurement are derived and applied, which refer to data collection, coding, and analysis. These criteria are evaluated using examples from a laddering study where additional data was collected to shed light on respondents' subj interpretation of the laddering task as well as interviewers' experiences with it. Several possible validity threats are identified, and ways to improve the method are suggested.

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

    Directory of Open Access Journals (Sweden)

    Mahmoud A. Barghash

    2011-01-01

    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.

  7. Fish Facts

    Science.gov (United States)

    ... 1 serving) per week. • Do not eat these fish, which are high in mercury: • Swordfish • Tilefish • King mackerel • Shark • Check before eating fish caught in local waters. State health departments have ...

  8. Fish Kids

    Science.gov (United States)

    ... and threaten the waters where we swim and fish. See all water resources . Water Bodies Oceans, Coasts, ... Systems More Wastewater resources Water Quality Beach Closures Fish Advisories How's My Waterway? More Water Quality resources ...

  9. Phase diagram for hard-core $\\mathbb{Z}_3$ anyons on the ladder

    OpenAIRE

    Pfeifer, Robert N. C.

    2015-01-01

    Low-dimensional quantum systems provide an important window onto the influence of particle statistics on collective behaviour, with the prototypical system being the two-leg ladder. Particle statistics in two dimensions are particularly rich, admitting not only bosonic and fermionic but also anyonic excitations, and while the behaviours of fermions and hard-core bosons on the ladder are well understood, the same cannot be said about anyons. Numerical analysis of the hard-cor...

  10. Ladder Dyson-Schwinger calculation of the anomalous gamma-3pi form factor

    OpenAIRE

    Cotanch, Stephen R.; Maris, Pieter,

    2003-01-01

    The anomalous processes, \\gamma \\to 3 \\pi and \\gamma \\pi \\to \\pi\\pi, are investigated within the Dyson-Schwinger framework using the rainbow-ladder approximation. Calculations reveal that a complete set of ladder diagrams beyond the impulse approximation are necessary to reproduce the fundamental low-energy theorem for the anomalous form factor. Higher momentum calculations also agree with the limited form factor data and exhibit the same resonance behavior as the phenomenol...

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

    OpenAIRE

    Masuda, T; A. Zheludev; Manaka, H.; Chung, J. -H.

    2005-01-01

    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 bondalternat...

  12. Magnetic and Caloric Properties of Ideal and Random Bond Quantum Spin Ladders in a Magnetic Field

    OpenAIRE

    Ryll, Hanjo

    2012-01-01

    A possible origin of new states of matter is one-dimensionality in quantum systems. These can be realised experimentally in magnetic insulators with antiferromagnetic exchange interactions. Among the currently most important systems being investigated for such novel macroscopic quantum phenomena are spin ladders. In this case, dimers of spin-1/2 magnetic moments form ”rungs” of the ladder and a cooperative quantum singlet phase evolves. The absolute strength of the antiferromagnetic exchange ...

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

    OpenAIRE

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

    2013-01-01

    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 fu...

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

    OpenAIRE

    Ayca Kangal

    2013-01-01

    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 s...

  15. Fish Aware: Textile Design as an Environmental Intervention. How textile design can be used as a medium to raise awareness of overfishing; and influence the pattern of fish consumption.

    OpenAIRE

    Barclay, Paula

    2013-01-01

    This thesis is a cooperation between WWF Finland and Makia Clothing, to create textile print designs within in a campaign context. The study specifically addresses the issue of overfishing, with the purpose to raise awareness and better sustainable practices within consumers and companies. Unsustainability has brought design and designers to a position where they have to think and design with an uncertain future in mind. There is no steady route to success or path to follow. Econom...

  16. A ladder polysilane as a template for folding palladium nanosheets.

    Science.gov (United States)

    Sunada, Yusuke; Haige, Ryohei; Otsuka, Kyohei; Kyushin, Soichiro; Nagashima, Hideo

    2013-01-01

    Although discrete nano-sized compounds consisting of a monolayer sheet of multiple atoms have attracted much attention, monolayer transition metal nanosheets are difficult to access. Here we report a template synthesis of the folding metal nanosheet (2) consisting of 11 palladium atoms by treatment of a ladder polysilane, decaisopropylbicyclo[2.2.0]hexasilane (1), with Pd(CN(t)Bu)2. Crystallographic analysis reveals that the compound is composed of two monolayer Pd7 sheets sharing three palladium atoms at the junction. Each Pd atom is stabilized by Pd-Si ?-bonds, Pd-Pd bonds and coordination of isocyanides. Ligand exchange of 2 from CN(t)Bu to CN(2,4,6-Me3-C6H2) is accompanied by structural rearrangement, leading to the formation of another folding Pd11 nanosheet (3) consisting of two edge-sharing Pd7 sheets. The shapes of the Pd7 sheets as well as the dihedral angle between the two Pd7 sheets are dependent on the substituent of the isocyanide ligand. PMID:23764831

  17. Petri net to ladder logic diagram converter and a batch process simulation

    Directory of Open Access Journals (Sweden)

    Mostafa M. Gomaa

    2011-02-01

    Full Text Available Discrete-event dynamic systems (DEDS are characterized by a set of states which the system can take, and by the set of asynchronous events that cause the state changes at discrete time points. Programmable logic controllers (PLCs are still important special purpose computers used to automate the DEDS in industry. Ladder logic diagrams (LLDs are still the most popular graphical programming tools of the PLCs; but the major problem is that programming is done heuristically and the LLDs are difficult to be used for both analysis and performance evaluation. Petri nets (PNs are nowadays the most effective modeling environment for both the design and implementation of DEDS. This paper proposes a PN to LLD conversion tool, used for graphical editing of a PN net model of a DEDS controller and for converting this PN into the equivalent LLD for programming a PLC. The conversion algorithm is presented, considering many types of transitions, places, and arcs with generality that many types of PNs can be considered. This paper also presents a simulation of a batch process, on a personal computer from one side, interfaced with a real PLC from the other side, that is programmed using a LLD obtained from the conversion of a suitable PN model using the proposed conversion tool. Compared with a LDD got heuristically, the LLD got from a PN conversion is simpler, understandable, and meeting all the characteristics obtained from the PN analysis.

  18. Anadromous fish behaviour important for fish passage

    International Nuclear Information System (INIS)

    An understanding of the behavior of target fish species is necessary for proper design, location, and operation of a successful upstream or downstream fishway for anadromous migrants. Important fish behaviors are seasonal and daily timing of migration; rheotaxis and near field behavior; stimulus-response behavior; swimming capability; shoaling behavior; response to physical environmental factors such as illumination, sound, water depth, current velocity, and structure; response to chemicals; and response to biological factors such as competition for space and response to predators. The information on migrant fish behavior is reviewed, using examples from the literature on the behavior of eastern anadromous species, particularly Atlantic salmon (Salmo salar) and American shad (Alosa sapidissima). 87 refs

  19. Who cares about fish welfare?

    DEFF Research Database (Denmark)

    Ellingsen, Kristian; Grimsrud, Kristine; Nielsen, Hanne Marie; Mejdell, Cecilie; Olesen, Ingrid; Honkanen, Pirjo; Navrud, Ståle; Gamborg, Christian; Sandøe, Peter

    2015-01-01

    Purpose – The purpose of this paper is threefold: first, to assess how concerned Norwegians are about fish welfare; second, to investigate Norwegians’ willingness to pay for salmon filet made from welfare-assured farmed fish with high levels of welfare; and third, to examine Norwegian opinions about the appropriate way to pay for better welfare standards in fish production. Design/methodology/approach – On the basis of two focus group sessions, a survey questionnaire was developed and distribute...

  20. Bosons with long-range interactions on two-leg ladders in artificial magnetic fields

    Science.gov (United States)

    Natu, Stefan S.

    2015-11-01

    Motivated by experiments exploring the physics of neutral atoms in artificial magnetic fields, we study the ground state of bosons interacting with long-range dipolar interactions on a two-leg ladder. We focus on the limit where the number of particles per site is large and the interactions are weak. Using two complementary variational approaches, we find rich physics driven by the long-range forces. Generically, long-range interactions tend to destroy the Meissner phase in favor of modulated density wave phases. For example, nearest-neighbor interactions produce an interleg charge density wave phase, where the total density remains uniform but the density on each leg of the ladder is modulating in space, out of phase with one another. Next-nearest-neighbor interactions lead to a fully modulated biased ladder phase, where all of the particles are on one leg of the ladder. This state simultaneously breaks Z2 reflection symmetry and U (1 ) translation symmetry. For values of the flux near ? =? , we find a switching effect for arbitrarily weak interactions, where the density is modulated but the chiral current changes sign on every plaquette. Arbitrarily weak attractive interactions along the rungs destroy the Meissner phase completely, in favor of a modulated density wave phase. Remarkably, varying the rung to ladder hopping produces a cascade of first-order transitions between modulated density wave states with different wave vectors, which manifests itself as discrete jumps in the chiral current. Polarizing the dipoles along the ladder direction yields a region of phase space where a stable biased ladder phase occurs even at arbitrarily weak rung hopping. We discuss the experimental consequences of our work and draw connections between our work and recent experiments on cold atoms in synthetic dimensions.

  1. Characteristics of ITO electrode grown by linear facing target sputtering with ladder type magnetic arrangement for organic light emitting diodes

    International Nuclear Information System (INIS)

    The preparation and characteristics of indium tin oxide (ITO) electrodes grown using a specially designed linear facing target sputtering (LFTS) system with a ladder type magnet arrangement for organic light emitting diodes (OLED) are described. It was found that the electrical and optical properties of the ITO electrode were critically dependent on the Ar/O2 flow ratio, while its structural and surface properties remained fairly constant regardless of the Ar/O2 flow ratio, due to the low substrate temperature during the plasma damage-free sputtering. Under the optimized conditions, we obtained an ITO electrode with the lowest sheet resistance of 39.4 ?/sq and high transmittance of 90.1% (550 nm wavelength) at room temperature. This suggests that LFTS is a promising low temperature and plasma damage free sputtering technology for preparing high-quality ITO electrodes for OLEDs and flexible OLEDs at room temperature.

  2. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Roux, G

    2007-07-15

    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)

  4. Hood River Pelton Ladder Studies : Annual Report 1995.

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-09-01

    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.

  5. Texture Fish

    Science.gov (United States)

    Stone, Julie

    2007-01-01

    In an effort to provide an opportunity for her first graders to explore texture through an engaging subject, the author developed a three-part lesson that features fish in a mixed-media artwork: (1) Exploring Textured Paint; (2) Creating the Fish; and (3) Role Playing. In this lesson, students effectively explore texture through painting, drawing,…

  6. Fish bioacoustics.

    Science.gov (United States)

    Ladich, Friedrich

    2014-10-01

    Bony fishes have evolved a diversity of sound generating mechanisms and produce a variety of sounds. By contrast to sound generating mechanisms, which are lacking in several taxa, all fish species possess inner ears for sound detection. Fishes may also have various accessory structures such as auditory ossicles to improve hearing. The distribution of sound generating mechanisms and accessory hearing structures among fishes indicates that acoustic communication was not the driving force in their evolution. It is proposed here that different constraints influenced hearing and sound production during fish evolution, namely certain life history traits (territoriality, mate attraction) in the case of sound generating mechanisms, and adaptation to different soundscapes (ambient noise conditions) in accessory hearing structures (Ecoacoustical constraints hypothesis). PMID:25062472

  7. Steady state behaviour in atomic three-level $\\lambda$ and ladder systems with incoherent population pumping

    CERN Document Server

    Blaauboer, M

    1997-01-01

    The steady state in three-level lambda and ladder systems is studied. It is well-known that in a lambda system this steady state is the coherent population trapping state, independent of the presence of spontaneous emission. In contrast, the steady state in a ladder system is in general not stable against radiative decay and exhibits a minimum in the population of the ground state. It is shown that incoherent population pumping destroys the stability of the coherent population trapping state in the lambda system and suppresses a previously discovered sharp dip in the steady state response. In the ladder system the observed minimum disappears in the presence of an incoherent pump on the upper transition.

  8. Dynamic Covalent Assembly of Peptoid-Based Ladder Oligomers by Vernier Templating.

    Science.gov (United States)

    Wei, Tao; Jung, Jae Hwan; Scott, Timothy F

    2015-12-30

    Dynamic covalent chemistry, in conjunction with template-directed assembly, enables the fabrication of extended nanostructures that are both precise and tough. Here we demonstrate the dynamic covalent assembly of peptoid-based molecular ladders with up to 12 rungs via scandium(III)-catalyzed imine metathesis by employing the principle of Vernier templating, where small precursor units with mismatched numbers of complementary functional groups are coreacted to yield larger structures with sizes determined by the respective precursor functionalities. Owing to their monomer diversity and synthetic accessibility, sequence-specific oligopeptoids bearing dynamic covalent pendant groups were employed as precursors for molecular ladder fabrication. The generated structures were characterized using matrix-assisted laser desorption/ionization mass spectrometry and gel permeation chromatography, confirming successful molecular ladder fabrication. PMID:26639351

  9. 36 CFR 2.3 - Fishing.

    Science.gov (United States)

    2010-07-01

    ...2010-07-01 2010-07-01 false Fishing. 2.3 Section 2.3 Parks...PUBLIC USE AND RECREATION § 2.3 Fishing. (a) Except in designated areas or as provided in this section, fishing shall be in accordance with...

  10. Do Fish Enhance Tank Mixing?

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Laursen, Jesper

    2005-01-01

    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.

  11. Duration of pregnancy in relation to fish oil supplementation and habitual fish intake: a randomised clinical trial with fish oil

    DEFF Research Database (Denmark)

    Olsen, Sjurdur Frodi; Østerdal, M L; Salvig, J D; Weber, T; Tabor, A; Secher, N J

    2007-01-01

    OBJECTIVE: To examine the effect of fish oil supplementation on duration of pregnancy, conditional on the woman's habitual fish intake. DESIGN: Multicentre 1:1 randomised clinical trial of effect of fish oil in a high-risk population of pregnant women in whom habitual fish intake was assessed at randomisation. SETTING: Nineteen university delivery wards in seven European countries. SUBJECTS: Pregnant women with preterm delivery, intrauterine growth retardation (IUGR), or pregnancy-induced hypert...

  12. Generalized two-leg Hubbard ladder at half-filling: Phase diagram and quantum criticalities

    OpenAIRE

    Tsuchiizu, M.; Furusaki, A.

    2002-01-01

    The ground-state phase diagram of the half-filled two-leg Hubbard ladder with inter-site Coulomb repulsions and exchange coupling is studied by using the strong-coupling perturbation theory and the weak-coupling bosonization method. Considered here as possible ground states of the ladder model are four types of density-wave states with different angular momentum (s-density-wave state, p-density-wave state, d-density-wave state, and f-density-wave state) and four types of qua...

  13. Study of Ladder-Type Price Based on the Utility Function and Time Series

    Directory of Open Access Journals (Sweden)

    Cong Zhang

    2013-07-01

    Full Text Available As the electricity ladder-type price scheme implemented into the trail stage, studying on it has attracted more and more attention. The present study evaluated the efficiency in energy conservation and timeliness of this scheme based on utility function and time sequence. The results show that the scheme can save energy to certain extend, but it can not work well for long. Taking Beijing as an example, ladder-type scheme can only stabilize 80% of Beijing residents’ electricity cost till 2014 and further regulations are required to adapt to the development of the society.

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

    International Nuclear Information System (INIS)

    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

  15. Construction of classical superintegrable systems with higher order integrals of motion from ladder operators

    International Nuclear Information System (INIS)

    We construct integrals of motion for multidimensional classical systems from ladder operators of one-dimensional systems. This method can be used to obtain new systems with higher order integrals. We show how these integrals generate a polynomial Poisson algebra. We consider a one-dimensional system with third order ladder operators and found a family of superintegrable systems with higher order integrals of motion. We obtain also the polynomial algebra generated by these integrals. We calculate numerically the trajectories and show that all bounded trajectories are closed.

  16. $NaV_{2}O_{5}$ as a quarter-filled ladder compound

    CERN Document Server

    Smolinski, H; Weber, W; Peuchert, U; Roth, G I; Weiden, M; Geibel, C

    1998-01-01

    A new X-ray diffraction study of the one-dimensional spin-Peierls compound with one type of V site, contrary to the previously postulated non-centrosymmetric P2$_1$mn structure with two types of V sites (V^{+4} and V^{+5}). Density functional calculations indicate that NaV_2O_5 is a quarter-filled ladder compound with the spins carried by V-O-V molecular orbitals on the rungs of the ladder. Estimates of the charge-transfer gap and the exchange coupling agree well with experiment and explain the insulating behavior of NaV_2O_5 and its magnetic properties.

  17. Climb the Green Ladder Make Your Company and Career More Sustainable

    CERN Document Server

    Fetzer, Amy V

    2009-01-01

    Want to make your workplace more sustainable, get ahead in your career and improve your reputation?. Want to help your company or organisation save money, boost profits and improve its brand?. Whatever your level or industry, from sales and management to government and teaching, Climb The Green Ladder offers practical knowledge to help you make a difference. Whether you'd like to transform your entire company or just get your colleagues recycling, Climb The Green Ladder will provide you with the tools and motivation to move your company (and career) towards a more successful, more sustainable

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

    OpenAIRE

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

    2004-01-01

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Paramita; Karmakar, S. N. [Condensed Matter Physics Division, Saha Institute of Nuclear Physics, Sector-I, Block-AF, Bidhannagar, Kolkata-700 064 (India); Maiti, Santanu K., E-mail: santanu.maiti@isical.ac.in [Physics and Applied Mathematics Unit, Indian Statistical Institute, 203 Barrackpore Trunk Road, Kolkata-700 108 (India)

    2014-09-15

    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.

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

    International Nuclear Information System (INIS)

    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. (paper)

  1. Fishing Forecasts

    Science.gov (United States)

    1988-01-01

    ROFFS stands for Roffer's Ocean Fishing Forecasting Service, Inc. Roffer combines satellite and computer technology with oceanographic information from several sources to produce frequently updated charts sometimes as often as 30 times a day showing clues to the location of marlin, sailfish, tuna, swordfish and a variety of other types. Also provides customized forecasts for racing boats and the shipping industry along with seasonal forecasts that allow the marine industry to formulate fishing strategies based on foreknowledge of the arrival and departure times of different fish. Roffs service exemplifies the potential for benefits to marine industries from satellite observations. Most notable results are reduced search time and substantial fuel savings.

  2. Do Fish Enhance Tank Mixing?

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Laursen, Jesper; Craig, Steven R.; McLean, Ewen

    2005-01-01

    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 co...

  3. Multiple Robotic Fish’s Target Search and Cooperative Hunting Strategies

    Directory of Open Access Journals (Sweden)

    Da Lin

    2013-07-01

    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:

  4. One Fish, Two Fish, Redfish, You Fish!

    Science.gov (United States)

    White, Katherine; Timmons, Maryellen; Medders, Paul

    2011-01-01

    The recreational fishing activity presented in this article provides a hands-on, problem-based experience for students; it unites biology, math, economics, environmental policy, and population dynamics concepts. In addition, the activity allows students to shape environmental policy in a realistic setting and evaluate their peers' work. By…

  5. Archaeological Fish Bones Online: a digital archive of Sydney fishes

    Directory of Open Access Journals (Sweden)

    Sarah Colley

    2010-12-01

    Full Text Available The article presents the Archaeological Fish Bone Images sustainable digital archive and XTF-based image search and presentation tools developed with University of Sydney Library. The archive contains over 500 images of modern and archaeological fish remains and was developed as part of an archaeological research project into colonial and traditional Aboriginal fishing practices in Sydney, New South Wales, Australia from c.3000 years ago to the late 19th century. Links are provided to research information about fish ecology and fishing, the cultural and historical significance of fish taxa and details of taxonomic and anatomical nomenclature. Archaeological fish-bone images at the University of Sydney The article explains how and why the archive was developed, and identifies and discusses the research implications of significant gaps in current fish reference collections. Archive content is useful to researchers who need to identify and interpret fish remains of the same or similar biological taxa from Sydney or elsewhere. The design of the archive and online tools is relevant to other applications that use digital images to aid identification and interpretation of archaeological and other collections.

  6. The effect of FM inter-ladder coupling in spin-1/2 AFM two-leg ladders in the presence of a magnetic field: Quantum Monte Carlo study

    International Nuclear Information System (INIS)

    We study the effect of inter-ladder ferromagnetic (FM) coupling in spin-1/2 two-leg ladders with antiferromagnetic (AFM) legs and rungs interactions using the stochastic series expansion quantum Monte Carlo. We have compared the results with the experimental measurement on Sr14?xCaxCu24O41 cuprate which is the candidate for spin-1/2 AFM two-leg ladders with FM inter-ladder interaction. A remarkable asymptotic behavior of susceptibility is observed at very low temperature. In the absence of the magnetic field, thermodynamic behavior of an individual spin-1/2 two-leg ladder is similar to coupled one up to ?0.5Jleg interaction. But, the gaped phase is not clear in the Jin=?0.2Jleg of FM coupled two-leg ladder even at low magnetic fields, which shows that the inter-ladder FM interaction can induce a new quantum ordered gapless phase at zero temperature

  7. Evaluation Practice and Theory: Up and down the Ladder of Abstraction

    Science.gov (United States)

    Leviton, Laura C.

    2015-01-01

    Debra Rog presented the 2014 Eleanor Chelimsky Forum address, offering ways to integrate evaluation theory and practice by abundant use of practice examples. These examples illustrate the effective use of the Ladder of Abstraction from semantics, working from the concrete to the abstract and back again.

  8. A Twisted Ladder: Relating the Fe Superconductors to the High Tc Cuprates

    Energy Technology Data Exchange (ETDEWEB)

    Berg, E.

    2010-05-26

    We construct a 2-leg ladder model of an Fe-pnictide superconductor and discuss its properties and relationship with the familiar 2-leg cuprate model. Our results suggest that the underlying pairing mechanism for the Fe-pnictide superconductors is similar to that for the cuprates.

  9. Convergence and Periodic Solutions for the Input Impedance of a Standard Ladder Network

    Science.gov (United States)

    Ucak, C.; Acar, C.

    2007-01-01

    The input impedance of an infinite ladder network is computed by using the recursive relation and by assuming that the input impedance does not change when a new block is added to the network. However, this assumption is not true in general and standard textbooks do not always treat these networks correctly. This paper develops a general solution…

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

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Beckmann, Suzanne C.

    2001-01-01

    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.

  11. Gap Caused by Strong Pairing in the Ladder Model of DNA Molecules

    International Nuclear Information System (INIS)

    By directly diagonalizing the Hamiltonian of the ladder model of deoxyribonucleic acid (DNA) molecules, the density of states is obtained. It is found that DNA behaves as a conductor when the interchain hopping is smaller than twice the intrachain one, otherwise, DNA behaves as a semiconductor. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. How to achieve in-phase locking in small-inductance Josephson junction ladder arrays

    International Nuclear Information System (INIS)

    We present the results of an analytical study of phase locking in externally loaded two-dimensional Josephson junction ladder arrays with small, but non-vanishing ring inductances. A Lyapunov stability based condition is found controlling realization of the radiating in-phase oscillation regime. copyright 1998 American Institute of Physics

  13. Louisiana ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for freshwater (inland) fish species in coastal Louisiana. Vector polygons represent water-bodies and...

  14. Hawaii ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for reef, marine, estuarine, and native stream fish species in coastal Hawaii. Vector polygons in this...

  15. Alabama ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, and freshwater fish species in Alabama. Vector polygons in this data set represent...

  16. Fish health and fish quality

    DEFF Research Database (Denmark)

    Ingerslev, Hans-Christian

    2010-01-01

    Aquaculture is an expanding worldwide industry producing an increasing amount of fish every year. The quality of the fish meat is dependent upon many biological and non-biological factors. Infectious diseases are known to cause bleedings and damage of the muscle tissue that may lead to scarring after recovery, which possibly will affect some quality parameters. However, until now it has not been examined if previous infections have an impact on the sensory characteristics of the meat after slaug...

  17. Pallet insertion glovebox/hood control ladder diagram. Final project report

    International Nuclear Information System (INIS)

    The pallet insertion glovebox/hood (G/H) is a special confinement space that will be designed to allow for insertion of pallets into the Stacker/Retriever (S/R) area. The S/R a large vault that is kept at negative 1 inches w.c. relative to the atmosphere and is used for the safe storage of special nuclear material. The S/R system uses a vehicle to move the special nuclear material that are placed on the pallets from the storage bins to input/output (I/O) stations and vice versa. As the name suggest the I/O stations are used to place the material into the S/R vault or to remove material from the S/R vault. The pallets are specially designed structures that will hold certain numbers of the material containers in a safe configuration. To store additional material containers, there is a need to insert additional pallets in the SIR vault. Due to the presence of radioactive contamination and the fact that the vault must be kept at a negative pressure at all times, one of the several I/O stations will be modified so that pallets could be inserted into the S/R vault. The ventilation system for the S/R area is a dedicated system that recirculates nitrogen with less than 5% oxygen by volume throughout the area while exhausting small option of the nitrogen to keep the S/R at negative 1 inches w.c. relative to the atmosphere. The rooms surrounding the G/H and the S/R area are maintained at negative of 0.3 inches w.c. relative to the outside atmosphere. Both the G/H and the control system for the G/H will be designed such that the confinement requirements of the S/R and the G/H system will not be jeopardized. A ladder diagram will be developed to illustrate the control system

  18. Cowlitz Falls fish passage

    International Nuclear Information System (INIS)

    The upper Cowlitz was once home to native salmon and steelhead. But the combined impacts of overharvest, farming, logging and road building hammered fish runs. And in the 1960s, a pair of hydroelectric dams blocked the migration path of ocean-returning and ocean-going fish. The lower Cowlitz still supports hatchery runs of chinook, coho and steelhead. But some 200 river miles in the upper river basin--much of it prime spawning and rearing habitat--have been virtually cut off from the ocean for over 26 years. Now the idea is to trap-and-haul salmon and steelhead both ways and bypass previously impassable obstacles in the path of anadromous fish. The plan can be summarized, for the sake of explanation, in three steps: (1) trap and haul adult fish--collect ocean-returning adult fish at the lowermost Cowlitz dam, and truck them upstream; (2) reseed--release the ripe adults above the uppermost dam, and let them spawn naturally, at the same time, supplement these runs with hatchery born fry that are reared and imprinted in ponds and net pens in the watershed; (3) trap and haul smolts--collection the new generation of young fish as they arrive at the uppermost Cowlitz dam, truck them past the three dams, and release them to continue their downstream migration to the sea. The critical part of any fish-collection system is the method of fish attraction. Scientists have to find the best combination of attraction system and screens that will guide young fish to the right spot, away from the turbine intakes. In the spring of 1994 a test was made of a prototype system of baffles and slots on the upriver face of the Cowlitz Falls Dam. The prototype worked at 90% efficiency in early tests, and it worked without the kind of expensive screening devices that have been installed on other dams. Now that the success of the attraction system has been verified, Harza engineers and consultants will design and build the appropriate collection part of the system

  19. Rendimiento de jitomate con diferentes métodos de cultivo hidropónico basados en doseles escaleriformes / Tomato yield with different hydroponic production methods based on ladder-shaped canopies

    Scientific Electronic Library Online (English)

    Felipe, Sánchez-Del-Castillo; Olmo Atxayácatl, Bastida-Cañada; Esaú del Carmen, Moreno-Pérez; Efraín, Contreras-Magaña; Jaime, Sahagún-Castellanos.

    2014-12-01

    Full Text Available El objetivo del presente trabajo fue comparar el rendimiento por unidad de superficie y tiempo que se puede lograr con sistemas de producción de plantas de jitomate en hidroponía bajo invernadero con la formación de doseles en forma de escalera (escaleriformes) en relación con los de dosel uniforme. [...] Se trabajó con plantas despuntadas para dejarles sólo tres racimos a cada una y así limitar su altura a menos de un metro. Las plantas se agruparon en hileras ubicadas a diferente altura para conformar cuatro modalidades distintos de dosel en forma de escalera y también se manejó un testigo de dosel uniforme con todas las hileras de plantas a la misma altura. Cada tratamiento de dosel escaleriforme se probó a dos densidades de población (11.1 y 15.5 plantas·m-2 de invernadero). Se utilizó un diseño en bloques al azar con tres repeticiones. Las variables estudiadas fueron el rendimiento y número de frutos por unidad de superficie y por planta, y el peso medio de los frutos. Se encontró que los doseles escaleriformes obtuvieron mayor rendimiento por unidad de superficie que el testigo uniforme. En estos doseles las plantas en alta densidad produjeron mayor rendimiento y número de frutos por unidad de superficie que las que crecieron con la menor densidad, en tanto que el peso medio de frutos no disminuyó significativamente. Abstract in english The objective of this study was to compare the yield per unit area and the time in which it can be achieved using hydroponic tomato plant production systems under greenhouse conditions, based on the formation of ladder-shaped in relation to uniform canopies. Plants were trimmed to leave only three c [...] lusters in each one, and thus limit their height to less than a meter. Plants were grouped in rows located at different heights to form four different modalities of ladder-shaped canopy and also a control was conducted with all the rows of plants located at the same height. Each ladder-shaped canopy treatment was tested at two population densities (11.1 and 15.5 plants·m-2 of greenhouse space). A randomized block design with nine treatments and three replications was used. Variables studied were: yield and number of fruits per plant and unit area, and mean fruit weight. It was found that plants in ladder-shaped canopies yielded more per unit area than those in the control with uniform canopy. In these canopies high density plants produced higher yields and number of fruit per unit area than those grown under lower density, whereas the mean fruit weight did not decrease significantly.

  20. 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)

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

    2005-07-01

    Full Text Available 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.

  1. 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)

    Heppell, Joël; Lorenzen, Niels

    1998-01-01

    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.

  2. 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

  3. Zero Temperature Phase Transition in Spin-ladders: Phase Diagram and Dynamical studies of Cu(Hp)Cl

    OpenAIRE

    Chaboussant, G.; Julien, M. -H.; Fagot-Revurat, Y.; Hanson, M. E.; Levy, L. P.; Berthier, C.; Horvatic, M.; Piovesana, O.

    1998-01-01

    In a magnetic field, spin-ladders undergo two zero-temperature phase transitions at the critical fields Hc1 and Hc2. An experimental review of static and dynamical properties of spin-ladders close to these critical points is presented. The scaling functions, universal to all quantum critical points in one-dimension, are extracted from (a) the thermodynamic quantities (magnetization) and (b) the dynamical functions (NMR relaxation). A simple mapping of strongly coupled spin l...

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

    DEFF Research Database (Denmark)

    Thielemann, B.; Rüegg, C.; Kiefer, K.; Rønnow, H.M.; Normand, B.; Bouillot, P.; Kollath, C.; Orignac, E.; Citro, R.; Giamarchi, T.; Läuchli, A.M.; Biner, D.; Krämer, K.W.; Wolff-Fabris, F.; Zapf, V.S.; Jaime, M.; Stahn, J.; Christensen, Niels Bech; Grenier, B.; McMorrow, D.F.; Mesot, J.

    2009-01-01

    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 ar...

  5. The energy ladder: A valid model for household fuel transitions in sub-Saharan Africa?

    Science.gov (United States)

    Toole, Rebecca

    This thesis explores the determinants of household cooking fuel use within the context of the energy ladder hypothesis. Rooted in economic theory, the hypothesis constructs a linear model of household energy use in developing countries. I draw on existing survey data assembled by the United States Agency for International Development (USAID) to construct a dataset of 26 sub-Saharan African countries. Using this, I assess the validity of the energy ladder in this geographical context. My analysis examines the relationship between wealth and cooking fuel use, as measured by the shares of households reporting the use of traditional, transitional or modern cooking fuels at the enumeration level, an administrative definition created for census sampling. I additionally test for the effects of other characteristics, such as asset ownership and demographic characteristics. Furthermore, I explore the differences in effects between rural and urban areas. I conclude that wealth is not the sole influencer of cooking fuel choice.

  6. Hopping ladder and power relaxation due to donor-acceptor pairs

    International Nuclear Information System (INIS)

    Hopping between donor-acceptor pairs leads to peculiar temperature dependence of the conductivity and the photoconductivity under subband gap illumination in the form of non-linear activation energies ladder. The correlated and uncorrelated distributions of pairs are considered and the conditions for the ladder existence are determined. The relaxation of the carrier concentration fluctuations is studied and power type decay is found. The temperature dependence of the exponent is calculated in agreement with the non-exponential decay of the pulse excited luminescence observed by Dean et al. The temperature dependence of the luminescence intensity also shows variable activation energy as found here. The exponent value ?=1.316 is also in agreement with the data for crystalline and amorphous materials. (author)

  7. Symmetry Protected Topological Phases in Spin Ladders with Two-body Interactions

    CERN Document Server

    Liu, Zheng-Xin; Han, Yong-Jian; Yi, Wei; Wen, Xiao-Gang

    2012-01-01

    Spin-1/2 two-legged ladders respecting inter-leg exchange symmetry and D2 spin rotation symmetry have new symmetry protected topological (SPT) phases which are different from the Haldane phase. Three of the new SPT phases are tx,ty,tz, which all have symmetry protected two-fold degenerate edge states on each end of the open boundaries. However, the edge states in different phases have different response to magnetic field. For example, the edge states in the tz phase will be split by the magnetic field along the z-direction, but not by the fields in the x- and y-directions. We give the Hamiltonian that realizes each SPT phase and demonstrate a proof-of-principle quantum simulation scheme for Hamiltonians of the t0 and tz phases based on coupled-QED-cavity ladder.

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

    Scientific Electronic Library Online (English)

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

    1999-12-01

    Full Text Available 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.

  9. Explaining choice option attractiveness by beliefs elicited by the laddering method

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Bech-Larsen, Tino

    2005-01-01

    It is a common approach to explain choice option attractiveness by beliefs about the choice option. The means'end chain model is used to distinguish between various types of beliefs, depending on whether the belief links the choice option to attributes, consequences, or values related to the choice option. The laddering method is used to elicit beliefs of all three types for a choice between conventional and organic pork. As a benchmark, beliefs were also elicited in the traditional way advocated by Ajzen and Fishbein. Using both sets of beliefs in a subsequent survey, it was shown that the beliefs elicited by the laddering method increase explanatory power with regard to choice option attractiveness beyond the beliefs elicited by the Ajzen and Fishbein method, and that this additional explanatory power was due to those beliefs which relate the choice option to concepts with a higher level of abstraction (consequences and values). Udgivelsesdato: APR

  10. Population transfer in the Na s-p Rydberg ladder by a chirped microwave pulse

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, H. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 (United States); Department of Physics and Mathematics, Aoyama Gakuin University, Fuchinobe, Sagamihara, Kanagawa 252-5258 (Japan); Gurian, J. H.; Gallagher, T. F. [Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 (United States)

    2011-12-15

    While quantum defects of nl Rydberg states of Na with l{>=}2 are nearly equal to zero, the quantum defects of ns and np states of Na are quite large due to the finite size of its ionic core. Since the Na ns and np states are energetically isolated from the higher angular momentum states of the same n, we can think of the Na ns and np Rydberg states as a specific example of a simple multilevel ladder system consisting of only alternating s and p angular momentum states. Here we report that population transfer in the Na s-p Rydberg ladder can be effectively achieved using a frequency-chirped microwave pulse, which couples only s and p states under suitable conditions.

  11. 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

  12. Ladder operators and associated algebra for position-dependent effective mass systems

    Science.gov (United States)

    Amir, Naila; Iqbal, Shahid

    2015-07-01

    An algebraic treatment of shape-invariant quantum-mechanical position-dependent effective mass systems is discussed. Using shape invariance, a general recipe for construction of ladder operators and associated algebraic structure of the pertaining system, is obtained. These operators are used to find exact solutions of general one-dimensional systems with spatially varying mass. We apply our formalism to specific translationally shape-invariant potentials having position-dependent effective mass.

  13. Electromagnetically induced absorption in a non-degenerate three-level ladder system

    OpenAIRE

    Whiting, Daniel J.; Bimbard, Erwan; Keaveney, James; Zentile, Mark A.; Adams, Charles S; Hughes, Ifan G

    2015-01-01

    We investigate, theoretically and experimentally, the transmission of light through a thermal vapour of three-level ladder-type atoms, in the presence of 2 counter-propagating control fields. A simple theoretical model predicts the presence of electromagnetically induced absorption (EIA) in this pure three-level system when the control field is resonant. Experimentally, we use $^{87}$Rb in a large magnetic field of 0.62~T to reach the hyperfine Paschen-Back regime and realis...

  14. Contest for Attention in a Quality-Ladder Model of Endogenous Growth

    OpenAIRE

    Grossmann, Volker

    2003-01-01

    This paper develops a quality-ladder model of endogenous growth to study the interplay between in-house R&D and marketing expenditure. Although promotional activity is modelled as purely wasteful competition among firms for attention, it unambiguously fosters innovation activity of firms, and possibly, leads to faster growth. This result rests on two premises which are consistent with empirical evidence. First, if firms incur higher sunk costs for marketing, concentration and firm sizes rise....

  15. Specific heat spectra of non-interacting fermions in a quasiperiodic ladder sequence

    International Nuclear Information System (INIS)

    We compute the specific heat spectra of non-interacting fermions whose energy spectrum was obtained from a quasiperiodic ladder sequence (Fibonacci and Rudin-Shapiro type), mimicking a DNA molecule model. The specific heat is calculated from their underlying multi-fractal energy spectrum, considering several values of energy densities. Comparisons are made with a real DNA sequence, namely the human chromosome 22 (Ch22)

  16. Practitioner competency assessment and career ladders as a recruiting and retention tool.

    Science.gov (United States)

    Reid, Russell T

    2004-06-01

    The assessment of competency for respiratory care practitioners involves a thorough understanding of what defines competence, the development of a well-planned, continuous process that starts with new employee orientation, and a clearly communicated set of staff expectations. Career ladders are a tool that can be used to aid staff retention and recruitment, thereby reducing multiple costs associated with a high employee turnover rate, and to encourage professional development and accountability while achieving important departmental objectives. PMID:15177244

  17. 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

  18. Fabrication of nanochannels with ladder nanostructure at the bottom using AFM nanoscratching method

    OpenAIRE

    Yan, Yongda; Geng, Yanquan; Hu, Zhenjiang; Zhao, Xuesen; Yu, Bowen; Zhang, Qi

    2014-01-01

    This letter presents a novel atomic force microscopy (AFM)-based nanomanufacturing method combining the tip scanning with the high-precision stage movement to fabricate nanochannels with ladder nanostructure at the bottom by continuous scanning with a fixed scan size. Different structures can be obtained according to the matching relation of the tip feeding velocity and the precision stage moving velocity. This relationship was first studied in detail to achieve nanochannels with different la...

  19. Coexistence of diffusive and ballistic transport in a simple spin ladder

    OpenAIRE

    Znidaric, Marko

    2013-01-01

    We show that in a nonintegrable spin ladder system with the XX type of coupling along the legs and the XXZ type along the rungs there are invariant subspaces that support ballistic magnetization transport. In the complementary subspace the transport is found to be diffusive. This shows that (i) quantum chaotic systems can possess ballistic subspaces, and (ii) diffusive and ballistic transport modes can coexist in a rather simple nonintegrable model. In the limit of an infini...

  20. An overview on the phase diagram of the frustrated two-leg ladder model

    OpenAIRE

    Hakobyan, T.; Hetherington, J. H.; Roger, M.

    2000-01-01

    Using Density-Matrix Renormalization Group, we investigate the general phase diagram of the frustrated two-leg ladder with Heisenberg interactions along legs, rungs and diagonals. We confirm that all antiferromagnetic gapped states belong to the same universality class as the Haldane phase. In a three-dimensional phase diagram, we determine a continuous surface with singularities in the string-order parameter or its first derivative, corresponding to a transition between two...

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

    CERN Document Server

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

    2003-01-01

    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.

  2. Comment on "Anomalous Thermal Conductivity of Frustrated Heisenberg Spin Chains and Ladders"

    OpenAIRE

    Heidrich-Meisner, F.; Honecker, A.; Cabra, D. C.; Brenig, W.

    2003-01-01

    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.

  3. Phase Diagram of the Holstein-Hubbard Two-Leg Ladder

    OpenAIRE

    Tam, Ka-Ming; Tsai, S. -W.; Campbell, D. K.; Neto, A. H. Castro

    2006-01-01

    Using a functional renormalization group method, we obtain the phase diagram of the two-leg ladder system within the Holstein-Hubbard model, which includes both electron-electron and electron-phonon interactions. Our renormalization group technique allows us to analyze the problem for both weak and strong electron-phonon coupling. We show that, in contrast results from conventional weak coupling studies, electron-phonon interactions can dominate electron-electron interaction...

  4. Fish habitat mitigation measures for hydrotechnical projects

    International Nuclear Information System (INIS)

    In recent years, the identification and mitigation of environmental impacts of hydrotechnical projects, particularly on fish and fish habitats, have become a major component of project planning and design. Potential impacts to fish and fish habitat may include increased fish mortality, decreased species diversity, and loss or decreases in fish production due to loss of habitat or alteration of its suitability. These impacts arise from flooding of riverine habitat, alteration of flow quantity and distribution, changes in morphology, and alteration of water quality, including suspended sediments, temperature, dissolved oxygen, and mercury. The results of a study for the Canadian Federal Department of Fisheries and Oceans Central and Arctic Region, examining fish habitat mitigation techniques for their applicability to hydrotechnical projects in Canada are summarized. The requirements for achievement and verification of the no net loss policy for a project are discussed. 10 refs., 2 tabs

  5. Applications of the Sensor Fish Technology

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Zhiqun; Carlson, Thomas J.; Duncan, Joanne P.; Richmond, Marshall C.

    2007-08-28

    The Sensor Fish is an autonomous device developed at Pacific Northwest National Laboratory for U.S. Department of Energy (DOE) and Army Corps of Engineers (COE) to better understand the physical conditions fish experience during passage through hydro-turbines and other dam bypass alternatives. Since its initial development in 1997, the Sensor Fish has undergone several design changes to improve its function and extend the range of its use. The most recent Sensor Fish design, the six-degree-of-freedom (6DOF) device, has been deployed successfully to characterize the environment fish experience when they pass through several hydroelectric projects along main stem Columbia and Snake Rivers in the Pacific Northwest. Just as information gathered from crash test dummies can affect automobile design with the installation of protective designs to lessen or prevent human injury, having sensor fish data to quantify accelerations, rotations, and pressure changes, helps identify fish injury mechanisms such as strike, turbulent shear, pressure, and inertial effects, including non-lethal ones such as stunning or signs of vestibular disruption that expose fish to a higher risk of predation by birds and piscivorous fish downstream following passage.

  6. Resonant states and wavepacket super-diffusion in intra-chain correlated ladders with diluted disorder.

    Science.gov (United States)

    de Moura, F A B F; Leão, F F S; Lyra, M L

    2011-04-01

    In this work, we study a tight-binding Hamiltonian model system of a binary correlated ladder with diluted disorder. We introduce intra-chain correlations between the on-site potentials by imposing that ?(i, s) = - ?(i, - s) where s = ± 1 indexes the two ladder chains. Further, we consider each ladder chain as composed of inter-penetrating ordered and random sub-chains. We show that the presence of a random on-site distribution in one of the inter-penetrating chains leads to Anderson localization except at a specific symmetric pair of energy eigenmodes. Further, by integrating the time-dependent Schroedinger equation, we follow the time-evolution of an initially localized one-electron wavepacket. We report that the remaining delocalized resonant modes are responsible for a super-diffusive spread of the wavepacket dispersion while the wavepacket participation function remains finite. A scaling analysis of the wavepacket distribution shows that it obeys a universal scaling form with the development of a power-law tail followed by a super-diffusively evolving cutoff. We obtain three exponents characterizing this super-diffusive dynamics and show that they satisfy a simple scaling relation. PMID:21415480

  7. 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

  8. Mean-Field Theory for Spin Ladders Using Angular-Momentum Coupled Bases

    CERN Document Server

    Piekarewicz, J

    1998-01-01

    We study properties of two-leg Heisenberg spin ladders in a mean-field approximation using a variety of angular-momentum coupled bases. The mean-field theory proposed by Gopalan, Rice, and Sigrist, which uses a rung basis, assumes that the mean-field ground state consists of a condensate of spin-singlets along the rungs of the ladder. We generalize this approach to larger angular-momentum coupled bases which incorporate---by their mere definition---a substantial fraction of the important short-range structure of these materials. In these bases the mean-field ground-state remains a condensate of spin singlet---but now with each involving a larger fraction of the spins in the ladder. As expected, the ``purity'' of the ground-state, as judged by the condensate fraction, increases with the size of the elementary block defining the basis. Moreover, the coupling to quasiparticle excitations becomes weaker as the size of the elementary block increases. Thus, the weak-coupling limit of the theory becomes an accurate ...

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

    CERN Document Server

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

    2004-01-01

    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.

  10. A clinical ladder program based on Carper's Fundamental Patterns of Knowing in Nursing.

    Science.gov (United States)

    Schmidt, Lee A; Nelson, Deana; Godfrey, Leah

    2003-03-01

    Clinical and career ladder programs were popular adjuncts to recruitment and retention during the nursing shortage of the 1980s. Programs commonly used Benner's work as an organizing framework and typically used activities such as continuing education credit, committee participation, work experience, certifications, academic degrees, community service, and performance appraisal scores as criteria for advancement. The authors present a unique clinical ladder program based on Carper's Fundamental Patterns of Knowing in Nursing. This philosophical work has been debated in the literature for many years, yet to the authors' knowledge, this work has never been used as the conceptual basis for program development. The four patterns of knowing in nursing were found to be consistent with the definition of professional nursing, and provided a meaningful organizing framework that was well received by staff registered nurses. An overall history of clinical ladders is presented, followed by the organization's prior experience with these programs, and finally the details of development and implementation of the program with plans for evaluation. PMID:12629301

  11. Fish hemoglobins

    Directory of Open Access Journals (Sweden)

    P.C. de Souza

    2007-06-01

    Full Text Available Vertebrate hemoglobin, contained in erythrocytes, is a globular protein with a quaternary structure composed of 4 globin chains (2 alpha and 2 beta and a prosthetic group named heme bound to each one. Having myoglobin as an ancestor, hemoglobin acquired the capacity to respond to chemical stimuli that modulate its function according to tissue requirements for oxygen. Fish are generally submitted to spatial and temporal O2 variations and have developed anatomical, physiological and biochemical strategies to adapt to the changing environmental gas availability. Structurally, most fish hemoglobins are tetrameric; however, those from some species such as lamprey and hagfish dissociate, being monomeric when oxygenated and oligomeric when deoxygenated. Fish blood frequently possesses several hemoglobins; the primary origin of this finding lies in the polymorphism that occurs in the globin loci, an aspect that may occasionally confer advantages to its carriers or even be a harmless evolutionary remnant. On the other hand, the functional properties exhibit different behaviors, ranging from a total absence of responses to allosteric regulation to drastic ones, such as the Root effect.

  12. Fish hemoglobins

    Scientific Electronic Library Online (English)

    P.C. de, Souza; G.O., Bonilla-Rodriguez.

    2007-06-01

    Full Text Available Vertebrate hemoglobin, contained in erythrocytes, is a globular protein with a quaternary structure composed of 4 globin chains (2 alpha and 2 beta) and a prosthetic group named heme bound to each one. Having myoglobin as an ancestor, hemoglobin acquired the capacity to respond to chemical stimuli t [...] hat modulate its function according to tissue requirements for oxygen. Fish are generally submitted to spatial and temporal O2 variations and have developed anatomical, physiological and biochemical strategies to adapt to the changing environmental gas availability. Structurally, most fish hemoglobins are tetrameric; however, those from some species such as lamprey and hagfish dissociate, being monomeric when oxygenated and oligomeric when deoxygenated. Fish blood frequently possesses several hemoglobins; the primary origin of this finding lies in the polymorphism that occurs in the globin loci, an aspect that may occasionally confer advantages to its carriers or even be a harmless evolutionary remnant. On the other hand, the functional properties exhibit different behaviors, ranging from a total absence of responses to allosteric regulation to drastic ones, such as the Root effect.

  13. Dam crossing by migrating fish. State of the technique

    International Nuclear Information System (INIS)

    In the first part of this paper, the present state of design of fish ways is reviewed, focusing on the interest and the limits of each type of fish facility. The second part deals with downstream migration problems at hydroelectric power plants: fish damage in spillways and hydraulic turbines and design of fish screening and other diversionary techniques used to prevent entry of downstream migrant into intakes. 14 refs., 13 figs

  14. Microbiological spoilage of fish and fish products

    DEFF Research Database (Denmark)

    Gram, Lone; Huss, Hans Henrik

    1996-01-01

    Spoilage of fresh and lightly preserved fish products is caused by microbial action. This paper reviews the current knowledge in terms of the microbiology of fish and fish products with particular emphasis on identification of specific spoilage bacteria and the qualitative and quantitative biochemical indicators of spoilage. Shewanzella putrefaciens and Pseudomonas spp. are the specific spoilage bacteria of iced fresh fish regardless of the origin of the fish. Modified atmosphere stored marine f...

  15. First-order commensurate-incommensurate magnetic phase transition in the coupled FM spin-1/2 two-leg ladders

    CERN Document Server

    Jahangiri, J; Mahdavifar, S; Shayesteh, S Farjami

    2015-01-01

    We consider the spin-1/2 two-leg ladders with ferromagnetic (FM) interactions along legs and rungs. Using the stochastic series expansion QMC method, we study the low-temperature magnetic behavior of the system. An isolated spin-1/2 FM two-leg ladder is in the gapped saturated FM phase at zero temperature. As soon as the spin-1/2 FM two-leg ladders are connected with antiferromagnetic (AFM) inter-ladder interaction, a first-order commensurate-incommensurate quantum phase transition occurs in the ground state magnetic phase diagram. In fact a jump in the magnetization curve is observed. We found that, coupled spin-1/2 FM two-leg ladders are in a nonmagnetic phase at zero temperature. Applying a magnetic field, the ground state of coupled spin-1/2 FM two-leg ladders remains in the nonmagnetic phase up to a quantum saturate critical field.

  16. 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

  17. Dynamic (Vibrational) and Static Structural Analysis of Ladder Frame

    OpenAIRE

    Ketan Gajanan Nalawade; Ashish Sabu; Baskar P

    2014-01-01

    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 ...

  18. First-order commensurate-incommensurate magnetic phase transition in the coupled FM spin-1/2 two-leg ladders

    OpenAIRE

    Jahangiri, J.; H Hadipour; Mahdavifar, S.; Shayesteh, S. Farjami

    2015-01-01

    We consider the spin-1/2 two-leg ladders with ferromagnetic (FM) interactions along legs and rungs. Using the stochastic series expansion QMC method, we study the low-temperature magnetic behavior of the system. An isolated spin-1/2 FM two-leg ladder is in the gapped saturated FM phase at zero temperature. As soon as the spin-1/2 FM two-leg ladders are connected with antiferromagnetic (AFM) inter-ladder interaction, a first-order commensurate-incommensurate quantum phase tra...

  19. FWS Special Designation Areas

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This data layer depicts the Special Designations that have been placed upon the lands and waters administered by the U.S. Fish and Wildlife Service (USFWS) in North...

  20. Fish Tales

    Energy Technology Data Exchange (ETDEWEB)

    McLerran, L.

    2010-07-06

    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.

  1. Sport Fishing Regulations

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The regulations for sport fishing on St. Vincent National Wildlife Refuge are outlined in this document. Fishing is only permitted from sunrise to sunset, and only...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-01

    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.

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

    DEFF Research Database (Denmark)

    SØrensen, Elin; Grunert, Klaus G.

    1996-01-01

    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.

  4. Hybrid seine for full fish community collections

    Science.gov (United States)

    McKenna, James E.; Waldt, Emily M.; Abbett, Ross; David, Anthony; Snyder, James

    2013-01-01

    Seines are simple and effective fish collection gears, but the net mesh size influences how well the catch represents the fish communities. We designed and tested a hybrid seine with a dual-mesh bag (1/4? and 1/8?) and compared the fish assemblage collected by each mesh. The fine-mesh net retained three times as many fish and collected more species (as many as eight), including representatives of several rare species, than did the coarser mesh. The dual-mesh bag permitted us to compare both sizes and species retained by each layer and to develop species-specific abundance correction factors, which allowed comparison of catches with the coarse-mesh seine used for earlier collections. The results indicate that a hybrid seine with coarse-mesh wings and a fine-mesh bag would enhance future studies of fish communities, especially when small-bodied fishes or early life stages are the research focus.

  5. COMPLIANCE STUDIES: WHAT ABOUT THE FISH?

    Energy Technology Data Exchange (ETDEWEB)

    Woodley, Christa M.; Fischer, Eric S.; Wagner, Katie A.; Weiland, Mark A.; Eppard, M. B.; Carlson, Thomas J.

    2013-08-21

    ABSTRACT It is understood that operational and structural conditions at hydroelectric facilities along with environmental conditions of the migration corridors affect the passage conditions for fish. Hydropower fish survival assessments at the individual- and population-level have progressed over the past decade with development of turbine simulation software and improvements in telemetry systems, in particular, micro-transmitters, cabled and autonomous receivers, and advanced statistical designs that provide precise estimates of passage routes and dam-passage survival. However, these approaches often ignore fish condition as a variable in passage and survival analyses. To account for fish condition effects on survival results, compliance statistical models often require increased numbers of tagged fish. For example, prior to and during migration, fish encounter numerous stressors (e.g., disease, predation, contact with structures, decompression events), all of which can cause physical and physiological stress, altering the probability of survival after passage through a dam or a series of dams. In addition, the effects of surgical transmitter implantation process or the transmitter itself may cause physiological stress, alter behavior, and/or decrease survival. Careful physiological evaluations can augment survival model assumptions, resultant data, and predictive scenarios. To exemplify this, surgeons concurrently noted fish condition and surgical implantation during a multi-dam compliance study in 2011. The analyses indicted that surgeon observations on fish condition and surgical outcomes were related to 24 h holding mortalities and fish that never detected after release. Short reach and long reach survival were related to surgical outcomes and fish condition, respectively.

  6. Plastic fish

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

    In terms of weight, the plastic pollution in the world’s oceans is estimated to be around 300,000 tonnes. This plastic comes from both land-based and ocean-based sources. A lecture at CERN by chemist Wolfgang Trettnak addressed this issue and highlighted the role of art in raising people’s awareness.   Artwork by Wolfgang Trettnak. Packaging materials, consumer goods (shoes, kids’ toys, etc.), leftovers from fishing and aquaculture activities… our oceans and beaches are full of plastic litter. Most of the debris from beaches is plastic bottles. “PET bottles have high durability and stability,” explains Wolfgang Trettnak, a chemist by education and artist from Austria, who gave a lecture on this topic organised by the Staff Association at CERN on 26 May. “PET degrades very slowly and the estimated lifetime of a bottle is 450 years.” In addition to the beach litter accumulated from human use, rivers bring several ki...

  7. Microbiological spoilage of fish and fish products

    DEFF Research Database (Denmark)

    Gram, Lone; Huss, Hans Henrik

    1996-01-01

    Spoilage of fresh and lightly preserved fish products is caused by microbial action. This paper reviews the current knowledge in terms of the microbiology of fish and fish products with particular emphasis on identification of specific spoilage bacteria and the qualitative and quantitative biochemical indicators of spoilage. Shewanzella putrefaciens and Pseudomonas spp. are the specific spoilage bacteria of iced fresh fish regardless of the origin of the fish. Modified atmosphere stored marine fish from temperate waters are spoiled by the CO2 resistant Photobacterium phosphoreum whereas Gram- positive bacteria are likely spoilers of CO2 packed fish from fresh or tropical waters. Fish products with high salt contents may spoil due to growth of halophilic bacteria (salted fish) or growth of anaerobic bacteria and yeasts (barrel salted fish). Whilst the spoilage of fresh and highly salted fish is well understood, much less is known about spoilage of lightly preserved fish products. It is concluded that the spoilage is probably caused by lactic acid bacteria, certain psychrotrophic Enterobacteriaceae and/or Photobacterium phosphoreum. However, more work is needed in this area

  8. Ground states of the doped four-leg t-J ladder

    International Nuclear Information System (INIS)

    Using density-matrix renormalization-group techniques, we have studied the ground states of the four-leg t-J ladder doped near half-filling. Depending upon J/t and the hole doping x, three characteristic types of ground states are found: (1) a state containing dx2-y2 pairs, (2) a striped charge-density wave (CDW) domain-wall state, and (3) a phase-separated regime. The CDW domain walls consist of fluctuating hole pairs and this state has significant dx2-y2 pair field correlations. copyright 1997 The American Physical Society

  9. Russian doll spectrum in a non-Abelian string-net ladder

    Science.gov (United States)

    Schulz, Marc Daniel; Dusuel, Sébastien; Vidal, Julien

    2015-04-01

    We study a string-net ladder in the presence of a string tension. Focusing on the simplest non-Abelian anyon theory with a quantum dimension larger than two, we determine the phase diagram and find a Russian doll spectrum featuring size-independent energy levels as well as highly degenerate zero-energy eigenstates. At the self-dual points, we compute the gap exactly by using a mapping onto the Temperley-Lieb chain. These results are in stark contrast with the ones obtained for Fibonacci or Ising theories.

  10. Russian doll spectrum in a non-Abelian string-net ladder

    OpenAIRE

    Schulz, M. D.; Dusuel, S.; Vidal, J

    2014-01-01

    We study a string-net ladder in the presence of a string tension. Focusing on the simplest non-Abelian anyon theory with a quantum dimension larger than two, we determine the phase diagram and find a Russian doll spectrum featuring size-independent energy levels as well as highly degenerate zero-energy eigenstates. At the self-dual points, we compute the gap exactly by using a mapping onto the Temperley-Lieb chain. These results are in stark constrast with the ones obtained ...

  11. Electromagnetically induced absorption in a non-degenerate three-level ladder system

    CERN Document Server

    Whiting, Daniel J; Keaveney, James; Zentile, Mark A; Adams, Charles S; Hughes, Ifan G

    2015-01-01

    We investigate, theoretically and experimentally, the transmission of light through a thermal vapour of three-level ladder-type atoms, in the presence of 2 counter-propagating control fields. A simple theoretical model predicts the presence of electromagnetically induced absorption (EIA) in this pure three-level system when the control field is resonant. Experimentally, we use $^{87}$Rb in a large magnetic field of 0.62~T to reach the hyperfine Paschen-Back regime and realise a non-degenerate three-level system. Experimental observations verify the predictions over a wide range of detunings.

  12. Ladder-type electromagnetically induced transparency using nanofiber-guided light in a warm atomic vapor

    Science.gov (United States)

    Jones, D. E.; Franson, J. D.; Pittman, T. B.

    2015-10-01

    We demonstrate ladder-type electromagnetically induced transparency (EIT) using an optical nanofiber suspended in a warm rubidium vapor. The signal and control fields are both guided along the nanofiber, which enables strong nonlinear interactions with the surrounding atoms at relatively low powers. Transit-time broadening is found to be a significant EIT decoherence mechanism in this tightly confined waveguiding geometry. Nonetheless, we observe significant EIT and controlled polarization rotation using control-field powers of only a few microwatts in this relatively robust warm-atom nanofiber system.

  13. Preparation of nondegenerate coherent superpositions in a three-state ladder system assisted by Stark Shifts

    CERN Document Server

    Sangouard, N; Shore, B W; Yatsenko, L P

    2006-01-01

    We propose a technique to prepare coherent superpositions of two nondegenerate quantum states in a three-state ladder system, driven by two simultaneous fields near resonance with an intermediate state. The technique, of potential application to enhancement of nonlinear processes, uses adiabatic passage assisted by dynamic Stark shifts induced by a third laser field. The method offers significant advantages over alternative techniques: (\\i) it does not require laser pulses of specific shape and duration and (\\ii) it requires less intense fields than schemes based on two-photon excitation with non-resonant intermediate states. We discuss possible experimental implementation for enhancement of frequency conversion in mercury atoms.

  14. The two-particle problem in a many-particle system; 1, Dynamically screened ladder approximation

    CERN Document Server

    Bornath, T; Schlanges, M; Bornath, Th.

    1999-01-01

    The two-particle problem within a nonequilibrium many-particle system is investigated in the framework of real-time Green's functions. Starting from the dynamically screened ladder approximation of the nonequlibrium Bethe-Salpeter equation, a nonequilibrium Dyson equation is given for two-time two-particle Green's functions. Thereby the well-known Kadanoff-Baym equations are generalized to the case of two-particle functions. The two-time structure of the equations is achieved in an exact way avoiding the so-called Shindo approximation. For the case of thermodynamic equilibrium, the differences to former results obtained for the effective two-particle hamiltonian are discussed.

  15. Dissipative Force and Laser Cooling of a Ladder-Type Three-Level Atom

    Science.gov (United States)

    Wang, Z. C.; Tan, L.

    2003-09-01

    A theoretical study is made of the dissipative force and Doppler cooling of a ladder-type three-level atom coupled to a travelling coherent light beam. The dependence of the force on parameters such as detunings, Rabi frequencies, spontaneous decay and coherence transfer rates is calculated numerically and shown graphically. Analytical expressions for the force are obtained for special parameter values. It is shown that for suitable choices of parameter values, it is possible to cool three-level atoms to temperatures down below the Doppler limit.

  16. Regge behaviour and Regge trajectory for ladder graphs in scalar $\\Phi^3$ field theory

    OpenAIRE

    Tuan, Richard Hong

    1996-01-01

    Using the gaussian representation for propagators (which can be proved to be exact in the infinite number of loops limit) we are able to derive the Regge behaviour for ladder graphs of $\\phi^3$ field theory in a completely new way. An analytic expression for the Regge trajectory $\\alpha (t/m^2)$ is found in terms of the mean-values of the Feynman $\\alpha$-parameters. $\\alpha (t/m^2)$ is calculated in the range $- 3.6 < t/m^2 < 0.8$. The intercept $\\alpha (0)$ agrees with tha...

  17. Three-photon coherence in a ladder-type atomic system

    CERN Document Server

    Noh, Heung-Ryoul

    2015-01-01

    We present a theoretical study of three-photon electromagnetically induced absorption for a ladder-type three-level atomic system. A probe beam was tuned to the lower line and two counter-propagating, linearly polarized coupling beams were tuned to the upper line. The system can be modeled with a three- (or five-) level scheme when the polarization directions of the coupling beams are parallel (or perpendicular). By calculating the absorption coefficients analytically for the two schemes, we found that the corresponding absorption coefficients were identical except for different transition strengths, and that the primitive scheme embedded in those schemes was a simple four-level scheme.

  18. A Review of Topography in Fish Culture in Nigeria Part 1

    OpenAIRE

    J.F.N. Abowei; P.A. Bariweni

    2011-01-01

    A review of topography in fish culture in Nigeria part two is aimed at bridging the technical language gap between the fish culturist and; both land surveyors and civil engineers. The fish culturists need to understand the principles in topography for good site selection in fish culture. The fish farmer can design and build fishponds, reservoirs and small dams and use existing topographical maps. An adequate knowledge of topography by fish culturist bridges the technical language gap between ...

  19. Magnetic dilution in the cadmium-doped spin ladder compound Cdx Cu1 - x (quinoxaline) Br2

    Science.gov (United States)

    Keith, Brian; Landee, Chris; Turnbull, Mark

    2011-03-01

    Both Cu (quinoxaline) (Br2) and Cu (quinoxaline) (Cl2) are examples of molecule-based magnets where the CuX4 dimers are linked into ladders by quinoxaline molecules, where X is either Cl or Br. The rung exchange occurs through the bridging halides while the rail exchange occurs through the quinoxaline rings. Introducing random rung interactions into the system [ Cu (quinoxaline) (Br2)1-x (Cl2)x ] has caused the spin gap to close, in contrast with the gapped pure spin ladder parents. Crystal growth of non-magnetic-doped molecular magnets, CdxCu1 - x (2 , 3 - dimethylpyrazine)Br2 , have been performed for several values of the nominal conentration, x, and have been confirmed. The magnetizations and susceptibilities of the magnetically diluted ladder assemblage are presented along with a comparison of the effects of dilution from the pure case (x=0).

  20. Pressure-induced superconductivity in the iron-based ladder material BaFe2S3

    Science.gov (United States)

    Takahashi, Hiroki; Sugimoto, Akira; Nambu, Yusuke; Yamauchi, Touru; Hirata, Yasuyuki; Kawakami, Takateru; Avdeev, Maxim; Matsubayashi, Kazuyuki; Du, Fei; Kawashima, Chizuru; Soeda, Hideto; Nakano, Satoshi; Uwatoko, Yoshiya; Ueda, Yutaka; Sato, Taku J.; Ohgushi, Kenya

    2015-10-01

    All the iron-based superconductors identified so far share a square lattice composed of Fe atoms as a common feature, despite having different crystal structures. In copper-based materials, the superconducting phase emerges not only in square-lattice structures but also in ladder structures. Yet iron-based superconductors without a square-lattice motif have not been found, despite being actively sought out. Here, we report the discovery of pressure-induced superconductivity in the iron-based spin-ladder material BaFe2S3, a Mott insulator with striped-type magnetic ordering below ~120 K. On the application of pressure this compound exhibits a metal-insulator transition at about 11 GPa, followed by the appearance of superconductivity below Tc = 14 K, right after the onset of the metallic phase. Our findings indicate that iron-based ladder compounds represent promising material platforms, in particular for studying the fundamentals of iron-based superconductivity.

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

    Science.gov (United States)

    Koizumi, Kenji; Masuyama, Shigeru

    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.

  2. Implementability of two-qubit unitary operations over the butterfly network and the ladder network with free classical communication

    Energy Technology Data Exchange (ETDEWEB)

    Akibue, Seiseki [Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo (Japan); Murao, Mio [Department of Physics, Graduate School of Science, The University of Tokyo, Tokyo, Japan and NanoQuine, The University of Tokyo, Tokyo (Japan)

    2014-12-04

    We investigate distributed implementation of two-qubit unitary operations over two primitive networks, the butterfly network and the ladder network, as a first step to apply network coding for quantum computation. By classifying two-qubit unitary operations in terms of the Kraus-Cirac number, the number of non-zero parameters describing the global part of two-qubit unitary operations, we analyze which class of two-qubit unitary operations is implementable over these networks with free classical communication. For the butterfly network, we show that two classes of two-qubit unitary operations, which contain all Clifford, controlled-unitary and matchgate operations, are implementable over the network. For the ladder network, we show that two-qubit unitary operations are implementable over the network if and only if their Kraus-Cirac number do not exceed the number of the bridges of the ladder.

  3. Implementability of two-qubit unitary operations over the butterfly network and the ladder network with free classical communication

    International Nuclear Information System (INIS)

    We investigate distributed implementation of two-qubit unitary operations over two primitive networks, the butterfly network and the ladder network, as a first step to apply network coding for quantum computation. By classifying two-qubit unitary operations in terms of the Kraus-Cirac number, the number of non-zero parameters describing the global part of two-qubit unitary operations, we analyze which class of two-qubit unitary operations is implementable over these networks with free classical communication. For the butterfly network, we show that two classes of two-qubit unitary operations, which contain all Clifford, controlled-unitary and matchgate operations, are implementable over the network. For the ladder network, we show that two-qubit unitary operations are implementable over the network if and only if their Kraus-Cirac number do not exceed the number of the bridges of the ladder

  4. Homogeneous line width of rare-earth-doped glasses for levels in a Stark level ladder: A new simple rule

    International Nuclear Information System (INIS)

    Concentrating on higher Stark states in multiplet ladders of lanthanide-doped glasses, we show that at 10 K, the homogeneous widths along Stark ladders vary quasi-linearly with the energy position in the ladder. Assuming that the mechanisms creating the homogeneous widths are first-order processes, either direct processes or two-phonon non-radiative transitions, the observed behavior is simply explained by the fact that energy separations between Stark levels for usual glasses are less, i.e., not far from kT D, the Debye energy. This in turn provides quasi-equal phonon transition probabilities between individual Stark states. A simple theoretical relationship is derived and compared with experiments

  5. Appearance of magnetic long range order in the spin ladder compound LaCuO2.5

    International Nuclear Information System (INIS)

    We report here the two current topics in the ladder compounds.1. The new ladder compound LaCuO2.5 recently discovered by Hiroi and Takano shows a clear sign of magnetic long range order at around 125 K observed by ?+SR technique. This result demonstrates that the ground state of LaCuO2.5 is not a spin liquid state, but a magnetically ordered state.2. Superconductivity has been found in the ladder material (Sr,Ca)14Cu24O41 under high pressure between 3 GPa and 4.5 GPa. The superconducting transition temperatures Tc (onset) are 12 K and 9 K at 3 GPa and 4.5 GPa, respectively

  6. Present Scenario of Landing and Distribution of Fish in Bangladesh

    OpenAIRE

    A.A.K.M. Nowsad; Hassan, M. N.; Hossain, M. B.; S.Khatun; Rahman, M.

    2013-01-01

    The present study was designed to know the landing and distribution pathways of fish and types and nature of stakeholders involved in fish distribution chain in Bangladesh. A total of 237 fish landing centers and 5440 markets were detected. The number of landing center and market were highest in Chittagong and Dhaka division respectively. Stakeholders in fish distribution, viz., arotdars, paikers and retailers were found to be 6219, 39506 and 122922, respectively. A 84.71% of the landin...

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

    DEFF Research Database (Denmark)

    Thielemann, B.; Rüegg, C.

    2009-01-01

    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.

  8. Electroreflectance and transfer-matrix analysis of Stark-ladder transitions in a GaAs/AlAs superlattice

    Science.gov (United States)

    Nakayama, M.; Tanaka, I.; Doguchi, T.; Koh, S.; Nishimura, H.; Kawashima, K.; Fujiwara, K.

    We have investigated Stark-ladder transitions in a GaAs(6.4 nm)/AlAs(0.9 nm) superlattice (SL) by using electroreflectance (ER) and photocurrent (PC) spectroscopy for the detection and a simple transfer-matrix (TM) method for the analysis. It is demonstrated that ER spectroscopies is much more sensitive to detect the Stark-ladder transitions than PC spectroscopy and that the TM method is powerful for the analysis. In addition, we discuss the resonant coupling between the Wannier-Stark localization states of the electron subbands from the ER results and the TM analysis.

  9. Review of mitigation methods for fish passage, instream flows, and water quality

    International Nuclear Information System (INIS)

    This paper reports on current environmental mitigation practices at nonfederal hydropower projects. Information was obtained from project operators on dissolved oxygen (DO) mitigation, instream flows, upstream fish passage facilities, and downstream fish passage facilities. The most common method for DO mitigation is the use of spill flows, which are costly because of lost power generation. DO concentrations are commonly monitored, but biological effects of DO mitigation are not. At many projects, instream flow requirements have been set without reference to formalized methods. About half of the projects with instream flow requirements monitor flow rates, but few monitor fish populations to verify that instream flows are effective. Angled bar racks are the most commonly used downstream fish passage devices and fish ladders are the most commonly used upstream fish passage devices. Fish passage rates or populations have been monitored to verify the effectiveness of passage mitigation at few projects. This analysis is the first phase of an evaluation of the costs, benefits, and effectiveness of mitigation measures

  10. Technologies for evaluating fish passage through turbines

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, Mark A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Carlson, Thomas J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2003-10-01

    This study evaluated the feasibility of two types of technologies to observe fish and near neutrally buoyant drogues as they move through hydropower turbines. Existing or reasonably modified light-emitting and ultrasonic technologies were used to observe flow patterns, the response of fish to flow, and interactions between fish and turbine structures with good spatial and temporal accuracy. This information can be used to assess the biological benefits of turbine design features such as reductions in gaps at the tips and hub of turbine runner blades, reshaping wicket gates and stay vanes, modifications to draft tube splitter piers, and design changes that enhance egress through the powerhouse and tailrace.

  11. Traditional fishing tools

    Directory of Open Access Journals (Sweden)

    STOICA Georgeta

    2009-09-01

    Full Text Available In this paper I present the traditional fishing tools used in the area of the Danube Delta. More precisely, I speak about the village of Sfantu Gheorghe, a traditional fishing village, where the fishing activity has been the main activity along the years and where, lately, there have been major changes due to the decrease of the fish species.

  12. Traditional fishing tools

    OpenAIRE

    Stoica, Georgeta

    2009-01-01

    In this paper I present the traditional fishing tools used in the area of the Danube Delta. More precisely, I speak about the village of Sfantu Gheorghe, a traditional fishing village, where the fishing activity has been the main activity along the years and where, lately, there have been major changes due to the decrease of the fish species.

  13. A general CFT model for antiferromagnetic spin-1/2 ladders with Mobius boundary conditions

    International Nuclear Information System (INIS)

    We show how the low energy properties of the two-leg XXZ spin-1/2 ladders with general anisotropy parameter ? on closed geometries can be accounted for in the framework of the m-reduction procedure developed previously (Cristofano et al 2000 Mod. Phys. Lett. A 15 547; Cristofano et al 2000 Mod. Phys. Lett. A 15 1679; Cristofano et al 2002 Nucl. Phys. B 641 547; Cristofano et al 2004 J. High Energy Phys. JHEP06(2004) 056). In the limit of quasi-decoupled chains, a conformal field theory (CFT) with central charge c = 2 is derived and its ability to describe the model with different boundary conditions is shown. Special emphasis is given to the Mobius boundary conditions which generate a topological defect corresponding to non-trivial single-spinon excitations. Then, in the case of the two-leg XXX ladders we discuss in detail the role of various perturbations in determining the renormalization group flow starting from the ultraviolet (UV) critical point with c = 2

  14. Some finite terms from ladder diagrams in three and four loop maximal supergravity

    CERN Document Server

    Basu, Anirban

    2015-01-01

    We consider the finite part of the leading local interactions in the low energy expansion of the four graviton amplitude from the ladder skeleton diagrams in maximal supergravity on T^2, at three and four loops. At three loops, we express the D^8 R^4 and D^{10} R^4 amplitudes as integrals over the moduli space of an underlying auxiliary geometry. These amplitudes are evaluated exactly for special values of the the moduli of the auxiliary geometry, where the integrand simplifies. We also perform a similar analysis for the D^8 R^4 amplitude at four loops that arise from the ladder skeleton diagrams for a special value of a parameter in the moduli space of the auxiliary geometry. While the dependence of the amplitudes on the volume of the T^2 is very simple, the dependence on the complex structure of the T^2 is quite intricate. In some of the cases, the amplitude consists of terms each of which factorizes into a product of two SL(2,Z) invariant modular forms. While one of the factors is a non--holomorphic Eisens...

  15. Defect motions and smearing of Shapiro steps in Josephson-junction ladders under magnetic frustration

    International Nuclear Information System (INIS)

    We present simulation results on the dynamics of 1D Josephson ladder arrays at zero temperature in the presence of uniform magnetic fields when dc plus ac currents are applied. For a frustration f=p/q, the dynamics of the array can be described by the reduced equations for only q variables, if the initial configuration is assumed to be invariant under the q-lattice translation. When dc plus ac currents are injected, fractional Shapiro steps are found at time-averaged voltage left-angle V right-angle=(n/q)(??/2e) with n an integer and ? the external driving frequency. If the ladder array is wound into an annular geometry, we can have defects in the vortex configuration depending on the initial random-phase configuration which cannot evolve into q-periodic states, and these defects are shown to smear the Shapiro steps. The dynamic resistance on the smeared Shapiro step is proportional to the number density of the defects

  16. Energy-efficient hydrogen separation by AB-type ladder-polymer molecular sieves

    KAUST Repository

    Ghanem, Bader

    2014-07-19

    The synthesis, microstructures, and exceptional gas transport properties of two new soluble ladder polymers, polymers of intrinsic microporosity (TPIM-1 and TPIM-2) containing triptycene moieties substituted with branched isopropyl and linear propyl chains at the 9,10-bridgeheads were reported. The precursor A-B monomers were modified with an o -difluoride functionality for enhanced activation for nucleophilic aromatic substitution. In a Schlenk tube, a mixture of the A-B monomer, 18-crown-6, anhydrous DMF and anhydrous potassium carbonate was stirred at 155 °C under nitrogen atmosphere for 20 min followed by the addition of toluene. The reaction was continued for another 45 min and more toluene was added. After another 45 min the reaction mixture was cooled to room temperature and poured into methanol. Slow evaporation of filtered, dilute 3-5 wt% chloroform solutions from a leveled glass plate yielded isotropic polymer films. Dry membranes were soaked in methanol for 24 h, air-dried, and then heated at 120°C for 24 h under high vacuum to remove any traces of residual solvent. TPIM-1 exhibits simultaneous boosts in permeability and selectivity, which highlights the significant potential of an isopropyl-substituted triptycene moiety as a contortion center for ladder PIMs.

  17. Fabrication of nanochannels with ladder nanostructure at the bottom using AFM nanoscratching method.

    Science.gov (United States)

    Yan, Yongda; Geng, Yanquan; Hu, Zhenjiang; Zhao, Xuesen; Yu, Bowen; Zhang, Qi

    2014-01-01

    This letter presents a novel atomic force microscopy (AFM)-based nanomanufacturing method combining the tip scanning with the high-precision stage movement to fabricate nanochannels with ladder nanostructure at the bottom by continuous scanning with a fixed scan size. Different structures can be obtained according to the matching relation of the tip feeding velocity and the precision stage moving velocity. This relationship was first studied in detail to achieve nanochannels with different ladder nanostructures at the bottom. Machining experiments were then performed to fabricate nanochannels on an aluminum alloy surface to demonstrate the capability of this AFM-based fabrication method presented in this study. Results show that the feed value and the tip orientation in the removing action play important roles in this method which has a significant effect on the machined surfaces. Finally, the capacity of this method to fabricate a large-scale nanochannel was also demonstrated. This method has the potential to advance the existing AFM tip-based nanomanufacturing technique of the formation these complex structures by increasing the removal speed, simplifying the processing procedure and achieving the large-scale nanofabrication. PMID:24940171

  18. Trait anxiety and goal difficulty on learning to climb the Bachman ladder.

    Science.gov (United States)

    Neiva, Jaqueline F O; Barros, Joao A C; Meira, Cassio M

    2014-04-01

    This study examined the effects of trait anxiety and goal setting on learning of the Bachman ladder. It was hypothesized that easy goals would increase learning for individuals with high trait anxiety while hard goals would increase learning for individuals with low trait anxiety. 80 high school students (40 boys, 40 girls; M age = 15 yr., SD = 1.0) filled out the Brazilian State-Trait Anxiety Inventory (STAI) for trait anxiety. The experiment was divided into four phases: acquisition, immediate transfer (after 5 min.), delayed transfer, and retention (after 24 hr.). On the transfer phases, the participants started climbing the ladder with the foot opposite of that used in acquisition. Participants were assigned to one of four experimental groups combining high and low anxiety traits and hard and easy goals. Variances were analyzed with repeated measurements on the last factor of all phases. The results showed the performance increased during the acquisition phase and no effects were observed in any phases. PMID:24897874

  19. Spinful fermionic ladders at incommensurate filling: Phase diagram, local perturbations, and ionic potentials

    Energy Technology Data Exchange (ETDEWEB)

    Carr, Sam T., E-mail: S.T.Carr@kent.ac.uk [School of Physical Sciences, University of Kent, Canterbury CT2 7NH (United Kingdom); Institut für Theorie der Kondensierten Materie, Karlsruher Institut für Technologie, 76128 Karlsruhe (Germany); DFG Center for Functional Nanostructures, Karlsruher Institut für Technologie, 76128 Karlsruhe (Germany); Narozhny, Boris N. [Institut für Theorie der Kondensierten Materie, Karlsruher Institut für Technologie, 76128 Karlsruhe (Germany); DFG Center for Functional Nanostructures, Karlsruher Institut für Technologie, 76128 Karlsruhe (Germany); Nersesyan, Alexander A. [The Abdus Salam International Centre for Theoretical Physics, 34100, Trieste (Italy)

    2013-12-15

    We study the effect of external potential on transport properties of the fermionic two-leg ladder model. The response of the system to a local perturbation is strongly dependent on the ground state properties of the system and especially on the dominant correlations. We categorize all phases and transitions in the model (for incommensurate filling) and introduce “hopping-driven transitions” that the system undergoes as the inter-chain hopping is increased from zero. We also describe the response of the system to an ionic potential. The physics of this effect is similar to that of the single impurity, except that the ionic potential can affect the bulk properties of the system and in particular induce true long range order. -- Highlights: •We study low temperature electronic properties of a two leg ladder. •We find a wide variety of phase transitions as a function of model parameters. •We study the effect of impurities on these models. •Conductance may be very sensitive to the structure of these impurities.

  20. Star formation relations and CO SLEDs across the J-ladder and redshift

    CERN Document Server

    Greve, T R; Xilouris, E M; Weiss, A; Zhang, Z -Y; van der Werf, P; Aalto, S; Armus, L; Diaz-Santos, T; Evans, A S; Fischer, J; Gao, Y; Gonzalez-Alfonso, E; Harris, A; Henkel, C; Meijerink, R; Naylor, D A; Smith, H A; Spaans, M; Stacey, G J; Veilleux, S; Walter, F

    2014-01-01

    We present FIR-CO luminosity relations ($\\log L_{\\rm FIR} = \\alpha \\log L'_{\\rm CO} + \\beta$) for the full CO rotational ladder from J=1-0 to J=13-12 for 62 local (z 1) by including 35 (sub)-millimeter selected dusty star forming galaxies from the literature with robust CO observations. The addition of luminous starbursts at high redshifts enlarge the range of the FIR-CO luminosity relations towards the high-IR-luminosity end while also significantly increasing the small amount of mid-/high-J CO line data available prior to Herschel. This new data-set (both in terms of IR luminosity and J-ladder) reveals linear FIR-CO luminosity relations ($\\alpha \\sim 1$) for J=1-0 up to J=5-4, with a nearly constant normalisation ($\\beta \\sim 2$). This is expected from the (also) linear FIR-(molecular line) relations found for the dense gas tracer lines (HCN and CS), as long as the dense gas mass fraction does not vary strongly within our (merger/starburst)-dominated sample. However from J=6-5 and up to J=13-12 we find an ...

  1. Single molecule studies of a ladder type conjugated polymer: vibronic spectra, line widths, and energy transfer.

    Science.gov (United States)

    Zickler, Martin F; Feist, Florian A; Jacob, Josemon; Müllen, Klaus; Basché, Thomas

    2015-06-01

    Confocal fluorescence microscopy and spectroscopy are employed to investigate single poly(ladder-type pentaphenylene) (LPPentP) molecules dispersed in thin poly(methyl methacrylate) (PMMA) films at 1.2 K. Emission spectra of single chains show single as well as multi-chromophore emission indicating variegated communication along the chains. The vibronic structure in the emission spectra resembles the one found for other ladder-type polymers. Purely electronic zero-phonon lines in emission are substantially broadened, most probably due to fast spectral diffusion. By surmounting the limitations of emission spectroscopy, nonemitting donor chromophores, which transfer their excitation energy in a radiationless manner to emitting chromophores, are accessed by excitation spectroscopy. Remarkably, by comparing the data of emitting and nonemitting chromophores a contribution to the zero-phonon excitation line width has to be considered which places a lower limit on the estimated energy transfer time of several picoseconds between adjacent chromophores. Finally, the data indicate qualitatively a restricted flexibility of LPPentP compared to poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). PMID:25823880

  2. Ladder operators and a dynamical SU(2) group symmetry of the hydrogen atom system

    International Nuclear Information System (INIS)

    By invoking a standard variable transformation x ? y ?  x2 that connects the eigenvalue problems of the hydrogen atom system (Coulomb potential) and the Kratzer oscillator system V(x)=(1/2)(m ?2x2+Kx?2), we obtain a system of ladder operators ?nl± (l  = 0,1,2, … ,n  ? 1) that connect the degenerate energy eigenstates (belonging to different l-values) of the hydrogen atom system. Using such quantum number specific operators as the precursors, we develop a general method of constructing quantum number independent ladder operators P-hat ±; and then investigate the general conditions for these operators to form a realization of the su(2) algebra. In the process, we demonstrate that, in general, a finite-dimensional linear vector space carries a realization of the su(2) algebra. Applying the method to the case at hand, we show that for the hydrogen atom system the operators P-hat ± and P-hat 0?(1/2)[ P-hat +, P-hat ?] form an su(2) algebra. The Hamiltonian is identified with the Casimir operator of the algebra, thereby revealing a dynamical SU(2) group symmetry of the hydrogen atom system. (paper)

  3. Magnetic excitations and phase diagram of the spin ladder material (Hpip)2CuCl4

    International Nuclear Information System (INIS)

    Full text: One-dimensional model magnets show generic features of low-dimensional systems with strong fluctuations. These enable important benchmark comparisons between experimental results and theoretical predictions. (Hpip)2CuCl4 is one of these materials, a 2 legged quasi-1D spin ladder compound, where the entire phase diagram is accessible, allowing for rich experiments in the plethora of phases. With rung and leg couplings of Jr=3.1 K and Jl=1.5 K respectively, comparisons can be made to the prototypical spin ladder (Hpip)2CuBr4 (Jr=12.8 K, Jl=3.2 K) which has considerably stronger exchange. Using neutron diffraction and inelastic scattering experiments, we determined the crystal structure as a function of temperature, the spin Hamiltonian and the the exchange parameters for(Hpip)2CuCl4. The phase diagram is explored via a temperature and field dependent study of the specific heat and is found to show the same phases and quantum critical points, except for a smaller coupling ratio Jr/Jl (weak coupling). We also explore the elementary excitations of the system by INS, which shows commensurate magnon modes with an energy gap Eg=0.18 meV. (author)

  4. Study of Pairing Correlations in the Attractive Hubbard Model on Chains, Ladders and Squares

    CERN Document Server

    Guerrero, M; Gubernatis, J E

    1999-01-01

    We report the results of zero temperature quantum Monte Carlo simulations and zero temperature mean-field calculations of the attractive Hubbard model on chains, ladders, and square lattices. We investigated the predictability of the BCS approximation, the dimensional cross-over of the pairing correlation function from one to two dimensions as a function of the ladder width, and the scaling of these correlations to the thermodynamic limit of the two-dimensional model. We found that the BCS wave function is quantitatively correct only for small values of $U/t$. For the system sizes, electron fillings, and interaction strengths studied, we never saw the dimensional cross-over. In general our ability to achieve the dimensional cross-over and accurate scaling to the thermodynamic limit was limited by the size of the systems we could simulate. For these sizes, although we saw the necessary signature of ODLRO, the properties of the model did not vary monotonically with increasing system size because of shell effect...

  5. Fish under exercise

    OpenAIRE

    Palstra, A.P.; Planas, J.V.

    2011-01-01

    Improved knowledge on the swimming physiology of fish and its application to fisheries science and aquaculture (i.e., farming a fitter fish) is currently needed in the face of global environmental changes, high fishing pressures, increased aquaculture production as well as increased concern on fish well-being. Here, we review existing data on teleost fish that indicate that sustained exercise at optimal speeds enhances muscle growth and has consequences for flesh quality. Potential added bene...

  6. Nutrition of ornamental fish.

    Science.gov (United States)

    Yanong, R P

    1999-01-01

    Because thousands of species comprise the aquarium hobby, ornamental fish nutrition is an art and a science that must be approached systematically and holistically. Examinations of species-specific anatomy and natural history are useful starting points. Food fish research provides fundamental nutritional information, but food fish are not ideal models for all ornamentals. This article briefly addresses freshwater and marine fish issues, including considerations for pond fish and live foods. PMID:11228692

  7. Laboratory Studies on the Effects of Shear on Fish

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, Duane A.; Richmond, Marshall C.; Dauble, Dennis D.; Mueller, Robert P.; Moursund, Russell A.; Abernethy, Cary S.; Guensch, Greg R.

    2000-09-20

    The overall objective of our studies was to specify an index describing the hydraulic force that fish experience when subjected to a shear environment. Fluid shear is a phenomenon that is important to fish. However, elevated levels of shear may result in strain rates that injure or kill fish. At hydroelectric generating facilities, concerns have been expressed that strain rates associated with passage through turbines, spillways, and fish bypass systems may adversely affect migrating fish. Development of fish friendly hydroelectric turbines requires knowledge of the physical forces (injury mechanisms) that impact entrained fish and the fish's tolerance to these forces. It requires up-front, pre-design specifications for the environmental conditions that occur within the turbine system, in other words, determining or assuming that those conditions known to injure fish will provide the descriptions of conditions that engineers must consider in the design of a turbine system. These biological specifications must be carefully and thoroughly documented throughout the design of a fish friendly turbine. To address the development of biological specifications, we designed and built a test facility where juvenile fish could be subjected to a range of shear environments and quantified their biological response.

  8. Consumer beliefs regarding farmed versus wild fish.

    Science.gov (United States)

    Claret, Anna; Guerrero, Luis; Ginés, Rafael; Grau, Amàlia; Hernández, M Dolores; Aguirre, Enaitz; Peleteiro, José Benito; Fernández-Pato, Carlos; Rodríguez-Rodríguez, Carmen

    2014-08-01

    Aquaculture is a food-producing activity, alternative to traditional extractive fishing, which still acts as a reference for most consumers. The main objective of the present paper was to study which consumer beliefs, regarding farmed versus wild fish, hinder the potential development of the aquaculture sector. To achieve this purpose the study was organized into two complementary steps: a qualitative approach (focus groups) aimed at assessing consumer perception about wild and farmed fish and to identify the salient beliefs that differentiate them; and a quantitative approach (survey by means of a questionnaire) to validate the results obtained in the focus group discussions over a representative sample of participants (n = 919). Results showed that participants perceive clear differences between farmed and wild fish. Although no significant differences between both kinds of fish were detected on safety, in general farmed fish was perceived to be less affected by marine pollution, heavy metals and parasites. In the contrary, wild fish was considered to have healthier feeding, to contain fewer antibiotics and to be fresher, healthier, less handled and more natural. Beliefs related to quality were in favour of wild fish, while those related to availability and price were in favour of farmed fish. Significant differences were observed in the perception of both kinds of fish depending on the consumers' objective knowledge about fish, on the level of education, age and gender and on the three segments of consumers identified: "Traditional/Conservative", "Connoisseur", "Open to aquaculture". The results provided could play an important role when planning and designing efficient marketing strategies for promoting farmed fish by adapting the information provided to the perception of each segment of consumers identified by the present study. PMID:24709486

  9. Push net fishing seems to be responsible for injuries and post fishing mortality in glass eel in the Vilaine estuary (France in 2007

    Directory of Open Access Journals (Sweden)

    Briand C.

    2012-01-01

    Full Text Available Post fishing mortality of the glass eel was monitored in 2007 in the Vilaine estuary. The mortality of the glass eels varied from 2 to 82% (mean 42% in the two days following the fishing. The mortality of samples collected by hand nets or from the trapping ladder was null. Alterations of the skin mucus were analyzed by the use of Indigo carmine. The mortality was significantly correlated with body injuries, but not to other environmental factors. The presence of a large injury on the body systematically led to the death of the glass eels, and among these dead glass eels, only 3.5% had no external injury. These results are discussed, along with the results from other estuaries, with a view to transport glass eels across Europe, with the objective of restoring the eel stock.

  10. The Bethe-Salpeter Equation for the Imaginary Part of the Scattering Amplitude in the Ladder Approximation

    CERN Document Server

    Gadjiev, S A

    2001-01-01

    Scattering amplitude of fermions and bosons in the ladder approximation at high energies is investigated. For the imaginary part of the scattering amplitude the set of Bethe-Salpeter type integral equations is constructed. Solutions of this set in the Regge asymptotic form are found. The impact of mass parameters on the behavior of the amplitude at high energies is studied.

  11. Knowing One's Lot in Life versus Climbing the Social Ladder: The Formation of Redistributive Preferences in Urban China

    Science.gov (United States)

    Smyth, Russell; Mishra, Vinod; Qian, Xiaolei

    2010-01-01

    This paper examines, how individual preferences for redistribution in general and redistribution to improve access to education, improve social protection for the poor, reduce income inequality and reduce unemployment depend on beliefs about what determines one's lot in life and self-assessed prospects for climbing the social ladder in urban…

  12. Heat transport imaging in the spin-ladder compound Ca9La5Cu24O41

    International Nuclear Information System (INIS)

    All-optical heat transport imaging on the spin-ladder compound Ca9La5Cu24O41 is presented. A 'time-of-flight' principle is discussed along with its experimental verification which can be used to measure the bulk thermal diffusion constant. The results of the thermal imaging experiments clearly demonstrate anisotropic magnon heat transport

  13. Non-monotonic mobility vs. length dependence observed in electrophoretic separation of 25 bp DNA ladder in Pluronic gels.

    Science.gov (United States)

    You, Seungyong; van Winkle, David

    2009-03-01

    We electrophoresed a double-stranded DNA ladder first in an agarose gel, then in gels of Pluronic F-127 at room temperature. The DNA ladder consisted of 19 discrete fragments ranging in length from 25 to 450 bp at 25 bp increments plus 500 bp. The DNA fragments were first separated in agarose gel and stacked normally with 25 bp having the highest mobility. A single lane of the separated DNA ladder in the agarose gel was inserted at the edge of a Pluronic gel slab. The DNA was electrophoresed from the agarose into the Pluronic gels perpendicular to the original separation axis. Mobilities of DNA fragments increased from 25 bp to 175 bp and then decreased from 175 bp to 500 bp. The 25 bp and 500 bp bands of the ladder had approximately the same mobility in several different Pluronic gel concentrations. Both were slower than most bands in between. The highest mobility fragments with length of 175 bp have 59.5 nm contour length which is about 3.5 times the diameter of a micelle (17 nm). This result suggests a crossover from chromatographic separation to electrophoretic separation for these short DNAs. This research is supported by the state of Florida (Martech) and Research Corporation.

  14. Double-helical - ladder structural transition in the B-DNA is induced by a loss of dispersion energy.

    Czech Academy of Sciences Publication Activity Database

    ?erný, Ji?í; Kabelá?, Martin; Hobza, Pavel

    2008-01-01

    Ro?. 130, ?. 47 (2008), s. 16055-16059. ISSN 0002-7863 R&D Projects: GA MŠk LC512; GA AV ?R IAA400550808 Institutional research plan: CEZ:AV0Z40550506 Keywords : B-DNA * double-helical structure * ladder-like structure Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 8.091, year: 2008

  15. Detection of apoptotic DNA ladder in pig leukocytes and its precision using LM - PCR (ligation mediated polymerase chain reaction).

    Czech Academy of Sciences Publication Activity Database

    Matalová, Eva; Španová, A.

    2002-01-01

    Ro?. 71, ?. 3 (2002), s. 163-168. ISSN 0001-7213 R&D Projects: GA ?R GA304/01/0850; GA AV ?R KSK6005114 Keywords : apoptosis * phagocytosis * DNA ladder Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 0.370, year: 2002

  16. Evaluating analytical approaches for estimating pelagic fish biomass using simulated fish communities

    Science.gov (United States)

    Yule, Daniel L.; Adams, Jean V.; Warner, David M.; Hrabik, Thomas R.; Kocovsky, Patrick M.; Weidel, Brian C.; Rudstam, Lars G.; Sullivan, Patrick J.

    2013-01-01

    Pelagic fish assessments often combine large amounts of acoustic-based fish density data and limited midwater trawl information to estimate species-specific biomass density. We compared the accuracy of five apportionment methods for estimating pelagic fish biomass density using simulated communities with known fish numbers that mimic Lakes Superior, Michigan, and Ontario, representing a range of fish community complexities. Across all apportionment methods, the error in the estimated biomass generally declined with increasing effort, but methods that accounted for community composition changes with water column depth performed best. Correlations between trawl catch and the true species composition were highest when more fish were caught, highlighting the benefits of targeted trawling in locations of high fish density. Pelagic fish surveys should incorporate geographic and water column depth stratification in the survey design, use apportionment methods that account for species-specific depth differences, target midwater trawling effort in areas of high fish density, and include at least 15 midwater trawls. With relatively basic biological information, simulations of fish communities and sampling programs can optimize effort allocation and reduce error in biomass estimates.

  17. Effect of fish size on transmission of fish-borne trematodes (Heterophyidae) to common carps (Cyprinus carpio) and implications for intervention

    OpenAIRE

    Boerlage, A.S.; Graat, E.A.M.; Verreth, J. A. J.; de Jong, M. C. M.

    2011-01-01

    Fish-borne trematodes are reported to affect the health of more than 40 million people worldwide. Few experimental studies are available on fish size dependent gain (attack rates of cercariae) or loss (mortality of metacercariae) of fish-borne trematodes. Aim was to quantify the relation between fish size and attack rates of fish-borne trematodes in common carps (Cyprinus carpio). Effect of fish size and cercariae dose were tested in a 3 × 4 factorial design with 5 fish per combination of tre...

  18. Environmental mitigation at hydroelectric projects. Volume 2, Benefits and costs of fish passage and protection

    Energy Technology Data Exchange (ETDEWEB)

    Francfort, J.E.; Rinehart, B.N.; Sommers, G.L. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Cada, G.F.; Jones, D.W. [Oak Ridge National Lab., TN (United States); Dauble, D.D. [Pacific Northwest Lab., Richland, WA (United States); Hunt, R.T. [Hunt (Richard) Associates, Inc., Concord, NH (United States); Costello, R.J. [Northwest Water Resources Advisory Services (United States)

    1994-01-01

    This study examines envirorunental mitigation practices that provide upstream and downstream fish passage and protection at hydroelectric projects. The study includes a survey of fish passage and protection mitigation practices at 1,825 hydroelectric plants regulated by the Federal Energy Regulatory Commission (FERC) to determine frequencies of occurrence, temporal trends, and regional practices based on FERC regions. The study also describes, in general terms, the fish passage/protection mitigation costs at 50 non-Federal hydroelectric projects. Sixteen case studies are used to examine in detail the benefits and costs of fish passage and protection. The 16 case studies include 15 FERC licensed or exempted hydroelectric projects and one Federally-owned and-operated hydroelectric project. The 16 hydroelectric projects are located in 12 states and range in capacity from 400 kilowatts to 840 megawatts. The fish passage and protection mitigation methods at the case studies include fish ladders and lifts, an Eicher screen, spill flows, airburst-cleaned inclined and cylindrical wedgewire screens, vertical barrier screens, and submerged traveling screens. The costs, benefits, monitoring methods, and operating characteristics of these and other mitigation methods used at the 16 case studies are examined.

  19. Thinking about going to the dentist: a Contemplation Ladder to assess dentally-avoidant individuals' readiness to go to a dentist

    Directory of Open Access Journals (Sweden)

    Hillstead M Blake

    2011-01-01

    Full Text Available Abstract Background The Transtheoretical Model suggests that individuals vary according to their readiness to change behavior. Previous work in smoking cessation and other health areas suggests that interventions are more successful when they are tailored to an individual's stage of change with regards to the specific behavior. We report on the performance of a single-item measure ("Ladder" to assess the readiness to change dental-avoidant behavior. Methods An existing Contemplation Ladder for assessing stage of change in smoking cessation was modified to assess readiness to go to a dentist. The resulting Ladder was administered to samples of English-speaking adolescents (USA, Spanish-speaking adults (USA, and Norwegian military recruits (Norway in order to assess construct validity. The Ladder was also administered to a sample of English-speaking avoidant adolescents and young adults who were enrolled in an intervention study (USA in order to assess criterion validity. All participants also had dental examinations, and completed other questionnaires. Correlations, chi square, t tests and one-way ANOVAs were used to assess relationships between variables. Results In two samples, participants who do not go to the dentist had significantly more teeth with caries; in a third sample, participants who do not go to the dentist had significantly worse caries. Ladder scores were not significantly related to age, gender, caries, or dental fear. However, Ladder scores were significantly related to statements of intention to visit a dentist in the future and the importance of oral health. In a preliminary finding, Ladder scores at baseline also predicted whether or not the participants decided to go to a dentist in the intervention sample. Conclusions The data provide support for the convergent and divergent construct validity of the Ladder, and preliminary support for its criterion validity. The lack of relationship between dental fear and Ladder scores suggests that avoidant individuals may be helped to decide to go to a dentist using interventions which do not explicitly target their fear.

  20. Phase diagram study of a dimerized spin-S zig–zag ladder

    International Nuclear Information System (INIS)

    The phase diagram of a frustrated spin-S zig–zag ladder is studied through different numerical and analytical methods. We show that for arbitrary S, there is a family of Hamiltonians for which a fully-dimerized state is an exact ground state, being the Majumdar–Ghosh point for a particular member of the family. We show that the system presents a transition between a dimerized phase to a Néel-like phase for S = 1/2, and spiral phases can appear for large S. The phase diagram is characterized by means of a generalization of the usual mean field approximation. The novelty in the present implementation is to consider the strongest coupled sites as the unit cell. The gap and the excitation spectrum is analyzed through the random phase approximation. Also, a perturbative treatment to obtain the critical points is discussed. Comparisons of the results with numerical methods like the Density Matrix Renormalization Group are also presented. (paper)

  1. Thermodynamic properties of anisotropic spin ladder in a longitudinal magnetic field

    Science.gov (United States)

    Rezania, H.

    2015-08-01

    We address thermodynamic properties of quasi-one dimensional two leg antiferromagnetic ladder in the presence of magnetic field. A generalized bond operator formalism is used to transform the spin model to a hard core bosonic gas. We have implemented Green's function approach to obtain the temperature dependence of spin excitation spectrum in field induced spin polarized phase. The results show energy gap that vanishes at critical magnetic field for fixed values of temperatures. We have also found the temperature dependence of the specific heat and magnetization component in the magnetic field direction for various magnetic field strengths and anisotropies in the Heisenberg interactions on both leg and rung couplings. At low temperatures, the specific heat is found to be monotonically increasing with temperature for magnetic fields in the spin polarized phase region. Furthermore we studied the temperature dependence of the longitudinal magnetization for different magnetic field and anisotropy parameters.

  2. Two-step rational extensions of the harmonic oscillator: exceptional orthogonal polynomials and ladder operators

    International Nuclear Information System (INIS)

    The type III Hermite Xm exceptional orthogonal polynomial family is generalized to a double-indexed one Xm1,m2 (with m1 even and m2 odd such that m2 > m1) and the corresponding rational extensions of the harmonic oscillator are constructed by using second-order supersymmetric quantum mechanics. The new polynomials are proved to be expressible in terms of mixed products of Hermite and pseudo-Hermite ones, while some of the associated potentials are linked with rational solutions of the Painlevé IV equation. A novel set of ladder operators for the extended oscillators is also built and shown to satisfy a polynomial Heisenberg algebra of order m2 ? m1 + 1, which may alternatively be interpreted in terms of a special type of (m2 ? m1 + 2)th-order shape invariance property. (paper)

  3. Persisting Meissner state and incommensurate phases of hard-core boson ladders in a flux

    Science.gov (United States)

    Di Dio, M.; De Palo, S.; Orignac, E.; Citro, R.; Chiofalo, M.-L.

    2015-08-01

    The phase diagram of a half-filled hard-core boson two-leg ladder in a flux is investigated by means of numerical simulations based on the density matrix renormalization group (DMRG) algorithm and bosonization. We calculate experimentally accessible observables such as the momentum distribution, as well as rung current, density wave, and bond-order wave correlation functions, allowing us to identify the Mott Meissner and Mott vortex states. We follow the transition from commensurate Meissner to incommensurate vortex state at increasing interchain hopping until the critical value [Piraud et al. Phys. Rev. B 91, 140406 (2015), 10.1103/PhysRevB.91.140406] above which the Meissner state is stable at any flux. For flux close to ? , and below the critical hopping, we observe the formation of a second incommensuration in the Mott vortex state that could be detectable in current experiments.

  4. Study of a four-level system in vee + ladder configuration

    CERN Document Server

    Bharti, Vineet

    2015-01-01

    We present the results of a theoretical study of a four-level atomic system in vee + ladder configuration using a density matrix analysis. The absorption and dispersion profiles are derived for a weak probe field and for varying strengths of the two strong control fields. For specificity, we choose energy levels of $^{87}$Rb, and present results for both stationary atoms and moving atoms in room temperature vapor. An electromagnetically induced absorption (EIA) peak with negative dispersion is observed at zero probe detuning when the control fields have equal strengths, which switches to electromagnetically induced transparency (EIT) with positive dispersion (due to splitting of the EIA peak) when the control fields are unequal. There is significant linewidth narrowing in thermal vapor.

  5. Resonance structure and stability of intense terahertz-driven semiconductor Wannier-Stark ladder

    Energy Technology Data Exchange (ETDEWEB)

    Karasawa, T.; Amano, T.; Kukuu, A.; Maeshima, N.; Hino, K. [Doctoral Program in Frontier Science, Graduate School of Pure and Applied Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

    2011-01-15

    We present a theoretical study of an electronic state in the semiconductor Wannier-Stark ladder (WSL) driven by an intense THz laser. Numerical calculations based on the R-matrix Floquet theory have revealed that the dynamic localization (DL) is unstable against the Fano resonance-like interminiband decay mechanism caused by the THz-mediated coupling, termed here the dynamic Fano resonance (DFR). The obtained result is sharply contrasted with the conventional understanding without the introduction of DFR that the degree of stability of the DL would be comparable to or more than that of the WSL with no THz laser (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. The Pan-STARRS 1 Photometric Reference Ladder, Release 12.0

    OpenAIRE

    Magnier, E.A.; Schlafly, E.; Finkbeiner, Douglas; Juric, M.; Tonry, J. L.; Burgett, W.S.; Chambers, K. C.; Flewelling, H. A.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Price, P.A.; Sweeney, W E; Stubbs, Christopher William

    2013-01-01

    As of 2012 Jan 21, the Pan-STARRS1 \\(3\\pi\\) Survey has observed the 3/4 of the sky visible from Hawaii with a minimum of 2 and mean of 7.6 observations in 5 filters, \\(g_{\\rm P1},r_{\\rm P1},i_{\\rm P1},z_{\\rm P1},y_{\\rm P1}\\). Now at the end of the second year of the mission, we are in a position to make an initial public release of a portion of this unprecedented dataset. This article describes the PS1 Photometric Ladder, Release 12.01 This is the first of a series of data...

  7. Exact ground states for the four-electron problem in a Hubbard ladder

    CERN Document Server

    Kovács, E; Kovacs, Endre; Gulacsi, Zsolt

    2006-01-01

    The exact ground state of four electrons in an arbitrary large two leg Hubbard ladder is deduced from nine analytic and explicit linear equations. The used procedure is described, and the properties of the ground state are analyzed. The method is based on the construction in r-space of the different type of orthogonal basis wave vectors which span the subspace of the Hilbert space containing the ground state. In order to do this, we start from the possible microconfigurations of the four particles within the system. These microconfigurations are then rotated, translated and spin-reversed in order to build up the basis vectors of the problem. A closed system of nine analytic linear equations is obtained whose secular equation, by its minimum energy solution, provides the ground state energy and the ground state wave function of the model.

  8. Calculating Three Loop Ladder and V-Topologies for Massive Operator Matrix Elements by Computer Algebra

    CERN Document Server

    Ablinger, J; Blümlein, J; De Freitas, A; von Manteuffel, A; Schneider, C

    2015-01-01

    Three loop ladder and $V$-topology diagrams contributing to the massive operator matrix element $A_{Qg}$ are calculated. The corresponding objects can all be expressed in terms of nested sums and recurrences depending on the Mellin variable $N$ and the dimensional parameter $\\varepsilon$. Given these representations, the desired Laurent series expansions in $\\varepsilon$ can be obtained with the help of our computer algebra toolbox. Here we rely on generalized hypergeometric functions and Mellin-Barnes representations, on difference ring algorithms for symbolic summation, on an optimized version of the multivariate Almkvist-Zeilberger algorithm for symbolic integration, and on new methods to calculate Laurent series solutions of coupled systems of differential equations. The solutions can be computed for general coefficient matrices directly for any basis also performing the expansion in the dimensional parameter in case it is expressible in terms of indefinite nested product-sum expressions. This structural ...

  9. Commutation-relation-preserving ladder operators for propagating optical fields in nonuniform lossy media

    DEFF Research Database (Denmark)

    Partanen, Mikko; Häyrynen, Teppo

    2015-01-01

    We have recently developed a quantized fluctuational electrodynamics (QFED) formalism to describe the quantum aspects of local thermal balance formation and to formulate the electromagnetic field ladder operators so that they no longer exhibit the anomalies reported for resonant structures. Here we show how the QFED can be used to resolve between the left and right propagating fields to bridge the QFED and the quantum optical input-output relations commonly used to describe selected quantum aspects of resonators. The generalized model introduces a density of states concept describing interference effects, which is instrumental in allowing an unambiguous separation of the fields and related quantum operators into left and right propagating parts. In addition to providing insight on the quantum treatment of interference, our results also provide the conclusive resolution of the long-standing enigma of the anomalous commutation relations of partially confined propagating fields.

  10. Study of a four-level system in vee + ladder configuration

    Science.gov (United States)

    Bharti, Vineet; Natarajan, Vasant

    2015-12-01

    We present the results of a theoretical study of a four-level atomic system in vee + ladder configuration using a density matrix analysis. The absorption and dispersion profiles are derived for a weak probe field and for varying strengths of the two strong control fields. For specificity, we choose energy levels of 87Rb, and present results for both stationary atoms and moving atoms in room temperature vapor. An electromagnetically induced absorption (EIA) peak with negative dispersion is observed at zero probe detuning when the control fields have equal strengths, which switches to electromagnetically induced transparency (EIT) with positive dispersion (due to splitting of the EIA peak) when the control fields are unequal. There is significant linewidth narrowing in thermal vapor.

  11. Massive 3-loop ladder diagrams for quarkonic local operator matrix elements

    International Nuclear Information System (INIS)

    3-loop diagrams of the ladder-type, which emerge for local quarkonic twist-2 operator matrix elements, are computed directly for general values of the Mellin variable N using Appell-function representations and applying modern summation technologies provided by the package Sigma and the method of hyperlogarithms. In some of the diagrams generalized harmonic sums with ??{1,1/2,2} emerge beyond the usual nested harmonic sums. As the asymptotic representation of the corresponding integrals shows, the generalized sums conspire giving well behaved expressions for large values of N. These diagrams contribute to the 3-loop heavy flavor Wilson coefficients of the structure functions in deep-inelastic scattering in the region Q2?m2.

  12. Massive 3-loop ladder diagrams for quarkonic local operator matrix elements

    Energy Technology Data Exchange (ETDEWEB)

    Ablinger, Jakob; Schneider, Carsten [Johannes Kepler Univ., Linz (Austria). Research Inst. for Symbolic Computation; Bluemlein, Johannes; Hasselhuhn, Alexander; Wissbrock, Fabian [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Klein, Sebastian [Technische Hochschule Aachen (Germany). Inst. fuer Theoretische Physik

    2012-06-15

    3-loop diagrams of the ladder-type, which emerge for local quarkonic twist-2 operator matrix elements, are computed directly for general values of the Mellin variable N using Appell-function representations and applying modern summation technologies provided by the package Sigma and the method of hyperlogarithms. In some of the diagrams generalized harmonic sums with {xi} element of {l_brace}1,1/2,2{r_brace} emerge beyond the usual nested harmonic sums. As the asymptotic representation of the corresponding integrals shows, the generalized sums conspire giving well behaved expressions for large values of N. These diagrams contribute to the 3-loop heavy flavor Wilson coefficients of the structure functions in deep-inelastic scattering in the region Q{sup 2} >> m{sup 2}.

  13. A renormalization approach to describe charge transport in quasiperiodic dangling backbone ladder (DBL)-DNA molecules

    International Nuclear Information System (INIS)

    Highlights: ? One-step renormalization approach to describe the DBL-DNA molecule. ? Electronic tight-binding Hamiltonian model. ? A quasiperiodic sequence to mimic the DNA nucleotides arrangement. ? Electronic transmission spectra. ? I-V characteristics. -- Abstract: We study the charge transport properties of a dangling backbone ladder (DBL)-DNA molecule focusing on a quasiperiodic arrangement of its constituent nucleotides forming a Rudin-Shapiro (RS) and Fibonacci (FB) Poly (CG) sequences, as well as a natural DNA sequence (Ch22) for the sake of comparison. Making use of a one-step renormalization process, the DBL-DNA molecule is modeled in terms of a one-dimensional tight-binding Hamiltonian to investigate its transmissivity and current-voltage (I-V) profiles. Beyond the semiconductor I-V characteristics, a striking similarity between the electronic transport properties of the RS quasiperiodic structure and the natural DNA sequence was found.

  14. A renormalization approach to describe charge transport in quasiperiodic dangling backbone ladder (DBL)-DNA molecules

    Science.gov (United States)

    Sarmento, R. G.; Fulco, U. L.; Albuquerque, E. L.; Caetano, E. W. S.; Freire, V. N.

    2011-10-01

    We study the charge transport properties of a dangling backbone ladder (DBL)-DNA molecule focusing on a quasiperiodic arrangement of its constituent nucleotides forming a Rudin-Shapiro (RS) and Fibonacci (FB) Poly (CG) sequences, as well as a natural DNA sequence (Ch22) for the sake of comparison. Making use of a one-step renormalization process, the DBL-DNA molecule is modeled in terms of a one-dimensional tight-binding Hamiltonian to investigate its transmissivity and current-voltage (I-V) profiles. Beyond the semiconductor I-V characteristics, a striking similarity between the electronic transport properties of the RS quasiperiodic structure and the natural DNA sequence was found.

  15. A renormalization approach to describe charge transport in quasiperiodic dangling backbone ladder (DBL)-DNA molecules

    Energy Technology Data Exchange (ETDEWEB)

    Sarmento, R.G. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Fulco, U.L. [Departamento de Biofisica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Albuquerque, E.L., E-mail: eudenilson@gmail.com [Departamento de Biofisica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, RN (Brazil); Caetano, E.W.S. [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara, 60040-531 Fortaleza, CE (Brazil); Freire, V.N. [Departamento de Fisica, Universidade Federal do Ceara, 60455-760 Fortaleza, CE (Brazil)

    2011-10-31

    Highlights: ? One-step renormalization approach to describe the DBL-DNA molecule. ? Electronic tight-binding Hamiltonian model. ? A quasiperiodic sequence to mimic the DNA nucleotides arrangement. ? Electronic transmission spectra. ? I-V characteristics. -- Abstract: We study the charge transport properties of a dangling backbone ladder (DBL)-DNA molecule focusing on a quasiperiodic arrangement of its constituent nucleotides forming a Rudin-Shapiro (RS) and Fibonacci (FB) Poly (CG) sequences, as well as a natural DNA sequence (Ch22) for the sake of comparison. Making use of a one-step renormalization process, the DBL-DNA molecule is modeled in terms of a one-dimensional tight-binding Hamiltonian to investigate its transmissivity and current-voltage (I-V) profiles. Beyond the semiconductor I-V characteristics, a striking similarity between the electronic transport properties of the RS quasiperiodic structure and the natural DNA sequence was found.

  16. Trichromatic ?-Pulse for Ultrafast Total Inversion of a Four-Level Ladder System

    Directory of Open Access Journals (Sweden)

    Carles Serrat

    2015-11-01

    Full Text Available We present a numerical solution for complete population inversion in a four-level ladder system obtained by using a full ?-pulse illumination scheme with resonant ultrashort phase-locked Gaussian laser pulses. We find that a set of pulse areas such as ?3? , ?2? , and ?3? completely inverts the four-level system considering identical effective dipole coupling coefficients. The solution is consistent provided the involved electric fields are not too strong and it is amply accurate also in the case of diverse transition dipole moments. We study the effect of detuning and chirp of the laser pulses on the complete population inversion using the level structure of atomic sodium interacting with ps and fs pulses as an example. Our result opens the door for multiple applications such as efficient ultrashort pulse lasing in the UV or the engineering of quantum states for quantum computing.

  17. A ladder of topologically non-trivial non-BPS states

    CERN Document Server

    Dorigoni, Daniele

    2014-01-01

    We consider a simple quiver gauge theory with gauge group U(r1) x U(r2) and a Higgs field in the bi-fundamental representation. The back-ground for this theory is a compact K\\"ahler manifold M. For a careful but natural choice of Higgs field potential the second order field equations can be replaced with a set of first order BPS equations. We show that the theory admits two energy gaps: The vacuum is topologically trivial but has finite, non-zero energy and is not a BPS state. The second gap lies between the vacuum and the first BPS state. In this gap we find a ladder of states with non-trivial topology, at equidistant energy levels. We give a semi-explicit construction for such topologically non-trivial non-BPS states.

  18. Development of an User-Friendly Virtual Environment for Design and Simulation of Food Processing Plants: Design and Simulation of Food Processing Plants: Application to the Valorization Process of Fish Skins to Obtain Gelatines

    OpenAIRE

    Otero-Muras, Irene; Antelo, L. T.; Pérez-Gálvez, Raúl; Alonso, Antonio A.

    2008-01-01

    The aim of this work is to develop a visual interface including the most representative processes in the gelatin production from fish skin. Connecting different components from a library implemented in EcosimPro, users can easily configure a virtual plant according to their requirements, and test different scenarios attending to the quantity and quality of the raw material (normally subject to seasonal variations). In this way, it is possible to analyze the consumption of water, ener...

  19. Some finite terms from ladder diagrams in three and four loop maximal supergravity

    Science.gov (United States)

    Basu, Anirban

    2015-10-01

    We consider the finite part of the leading local interactions in the low energy expansion of the four graviton amplitude from the ladder skeleton diagrams in maximal supergravity on T 2, at three and four loops. At three loops, we express the {D}8{{R}}4 and {D}10{{R}}4 amplitudes as integrals over the moduli space of an underlying auxiliary geometry. These amplitudes are evaluated exactly for special values of the the moduli of the auxiliary geometry, where the integrand simplifies. We also perform a similar analysis for the {D}8{{R}}4 amplitude at four loops that arise from the ladder skeleton diagrams for a special value of a parameter in the moduli space of the auxiliary geometry. While the dependence of the amplitudes on the volume of the T 2 is very simple, the dependence on the complex structure of the T 2 is quite intricate. In some of the cases, the amplitude consists of terms each of which factorizes into a product of two {SL}(2,{{Z}}) invariant modular forms. While one of the factors is a non-holomorphic Eisenstein series, the other factor splits into a sum of modular forms each of which satisfies a Poisson equation on moduli space with source terms that are bilinear in the Eisenstein series. This leads to several possible perturbative contributions unto genus 5 in type II string theory on S1. Unlike the one and two loop supergravity analysis, these amplitudes also receive non-perturbative contributions from bound states of three D-(anti)instantons in the IIB theory.

  20. 49 CFR 173.218 - Fish meal or fish scrap.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Fish meal or fish scrap. 173.218 Section 173.218... Fish meal or fish scrap. (a) Except as provided in Column (7) of the HMT in § 172.101 of this subchapter, fish meal or fish scrap, containing at least 6%, but not more than 12% water, is authorized...

  1. Got a Sick Fish?

    Science.gov (United States)

    ... hard surfaces Unusual isolation from the group of fish (if housed with others) Skin lesions/sores anywhere ... body Bloating Crooked back or other changes in fish shape or size Many of the following signs ...

  2. Ciguatera Fish Poisoning

    Science.gov (United States)

    Ciguatera Fish Poisoning Causative organisms: Gambierdiscus toxicus , Prorocentrum spp., Ostreopsis spp., Coolia monotis , Thecadinium spp. and Amphidinium carterae Toxins produced: Ciguatoxin/Maitotoxin Ciguatera Fish Poisoning (CFP) produces gastrointestinal, neurological, and cardiovascular ...

  3. Meat, Poultry and Fish

    Science.gov (United States)

    ... Friendly Worksites Program Requirements Fit-Friendly Resources Meat, Poultry and Fish Updated:May 4,2015 AHA Recommendation Choose fish, shellfish, poultry without the skin, and trimmed lean meats, no ...

  4. Compatibility Determination : Recreational Fishing

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — It is determined in this document that recreational fishing of bass and brim on St. Vincent National Wildlife Refuge is consistent with Refuge Objectives. The...

  5. Alaskan sport fishing waters

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — As a guide to newcomers and visitors, fishery biologists have compiled a list of some of the wellknown fishing waters in Alaska. The list is merely a starting point...

  6. Ciguatera fish poisoning

    OpenAIRE

    Crump, J.; McLay, C.; Chambers, S

    1999-01-01

    Ciguatera fish poisoning is one of a variety of non-bacterial forms of human seafood poisoning. Consuming large predatory fish from tropical reef ecosystems may be hazardous. We describe a case that is typical of the disease, and illustrates the persistence of neurological symptoms that occur in some patients.???Keywords: ciguatera fish poisoning; ichthyosarcotoxaemia; poisoning; biotoxins

  7. Swimming and muscle structure in fish

    OpenAIRE

    Spierts, I.L.Y.

    1999-01-01

    In this series of studies the relations between swimming behaviour of fish in general and extreme swimming responses in particular (called fast starts or escape responses) and the structure and ontogeny of the muscle system was investigated. Special attention was paid to relate functional differences between anterior and posterior parts of the axial myotomal muscles of fish to differences in their structural design. In the past considerable knowledge has been accumulated concerning the muscul...

  8. Fish Cam: An Online Tool for Introducing Shoaling Behavior to the Classroom

    OpenAIRE

    Southwell, Maura; Galassi, Maria; McRobert, Scott

    2012-01-01

    Fish Cam is an on-line educational resource that enables students to participate in behavioral research projects without ever leaving their classroom. By linking onto the Fish Cam site, students will observe an experimental tank in which fish choose shoal-mates in dichotomous choice tests. In these experiments, a test fish, in the central compartment, displays its shoaling preference by swimming near small shoals of fish in either of two side compartments. Assays are designed to examine the e...

  9. Duration of pregnancy in relation to fish oil supplementation and habitual fish intake: a randomised clinical trial with fish oil.

    DEFF Research Database (Denmark)

    Olsen, Sjurdur Frodi; Østerdal, M L

    2007-01-01

    OBJECTIVE: To examine the effect of fish oil supplementation on duration of pregnancy, conditional on the woman's habitual fish intake. DESIGN: Multicentre 1:1 randomised clinical trial of effect of fish oil in a high-risk population of pregnant women in whom habitual fish intake was assessed at randomisation. SETTING: Nineteen university delivery wards in seven European countries. SUBJECTS: Pregnant women with preterm delivery, intrauterine growth retardation (IUGR), or pregnancy-induced hypertension (PIH) in a previous pregnancy (group 1, n=495); with twin pregnancies (group 2, n=367); or with suspicion of IUGR or threatening preeclampsia in the current pregnancy (group 3, n=106). Women were stratified into low, middle, or high fish consumers. METHODS: The intervention group received fish oil capsules providing 2.7 g long-chain n-3 fatty acids per day (n-3 poly unsaturated fatty acids (PUFA)) from around week 20 (groups 1 and 2) or 6.3 g n-3 PUFA from week 33 (group 3). The control regimen was capsules witholive oil. Effect on timing of spontaneous delivery was examined by Cox regression, assuming elective delivery (occurring in 40%) as a censoring event. Analyses of effect of fish oil were intention to treat, and all analyses were adjusted for maternal smoking, age, and parity. RESULTS: In group 1, fish oil reduced the hazard rate of spontaneous delivery (HR) by 44% (95% confidence interval 14-64%) and 39% (16-56%) in low and middle fish consumers, respectively, with no detectable effect (-56 to 33%) in high fish consumers. In groups 2 and 3, no significant effect of fish oil was detected in any of the sub-strata defined by baseline fish consumption. CONCLUSIONS: In pregnant women with previous pregnancy complications, fish oil supplementation delayed onset of delivery in low and middle, but not in high, fish consumers. SPONSORSHIP: March of Dimes Birth Defects Foundation, Concerted Action (ERB-BMH1-CT92-1906) and PECO (ERB-CIPD-CT94-0235) programmes of the European Commission, and the Danish National Research Foundation. Lube Ltd donated the oil capsules. Udgivelsesdato: 2007-Aug

  10. Three Kinds of Fish : Buying, Selling and Leasing of FIshing Rights in Danish Commercial Fisheries

    DEFF Research Database (Denmark)

    HØst, Jeppe Engset

    2012-01-01

    There are three kinds of fish. Fish you were given, fish you bought and fish you lease. This might sound a bit odd, but it is nevertheless the basis for the activities of Danish commercial fishers since the introduction of transferable fishing concessions (TFCs) in 2007. In the current 2012 reform of the Common Fisheries Policy in the European Union, the European Commission are pushing for a “Danish model”, arguing in a briefing paper that experience in a member state “where a TFC system is used shows that risks can be avoided through design” (European Commission on Fisheries 2012:2). The known risks of market based systems are wild speculation, concentration and monopolization of fishing access and subsequent leasing with fishing communities and new entrants very likely being worse off (see for example the chapter “From fishing rights to financial derivatives” is this volume or Olson 2011; Sumaila 2010; Eythorsson 1996). Thus, there is a lot of focus on the design and so-called safeguards of TFCs in order to curb market forces (Høst 2012). Less focus has been directed towards the implications of a market economy for how everyday practices among fishers are fundamentally changed. In this article I will examine five Danish fishing operations and discuss how they have reacted in different ways to the newly introduced system of transferable fishing concessions. By introducing TFCs as a solution to fleet overcapacity, the EU Commission will also be introducing a system where buying, selling and leasing of fish will change forever the social relations in commercial fisheries.

  11. Three Kinds of Fish

    DEFF Research Database (Denmark)

    Høst, Jeppe Engset

    2012-01-01

    There are three kinds of fish. Fish you were given, fish you bought and fish you lease. This might sound a bit odd, but it is nevertheless the basis for the activities of Danish commercial fishers since the introduction of transferable fishing concessions (TFCs) in 2007. In the current 2012 reform of the Common Fisheries Policy in the European Union, the European Commission are pushing for a “Danish model”, arguing in a briefing paper that experience in a member state “where a TFC system is used...

  12. Hole distribution for (Sr,Ca,Y,La)_14 Cu_24 O_41 ladder compounds studied by x-ray absorption spectroscopy

    CERN Document Server

    Nücker, N; Kuntscher, C A; Gerhold, S; Schuppler, S; Neudert, R; Golden, M S; Fink, J; Schild, D; Stadler, S; Chakarian, V; Freeland, J; Idzerda, Yu; Conder, K; Uehara, M; Nagata, T; Goto, J; Akimitsu, J; Motoyama, N; Eisaki, H; Uchida, S I; Ammerahl, U; Revcolevschi, A

    2000-01-01

    The unoccupied electronic structure for the Sr_14Cu_24O_41 family of two-leg ladder compounds was investigated for different partial substitutions of Sr^2+ by Ca^2+, leaving the nominal hole count constant, and by Y^3+ or La^3+, reducing the nominal hole count from its full value of 6 per formula unit. Using polarization-dependent x-ray absorption spectroscopy on single crystals, hole states on both the chain and ladder sites could be studied. While for intermediate hole counts all holes reside on O sites of the chains, a partial hole occupation on the ladder sites in orbitals oriented along the legs is observed for the fully doped compound Sr_14Cu_24O_41. On substitution of Ca for Sr orbitals within the ladder planes but perpendicular to the legs receive some hole occupation as well.

  13. Augmented fish health monitoring

    International Nuclear Information System (INIS)

    The Bonneville Power Administration (BPA) initiated the Augmented Fish Health Monitoring project in 1986. This project was a five year interagency project involving fish rearing agencies in the Columbia Basin. Historically, all agencies involved with fish health in the Columbia Basin were conducting various levels of fish health monitoring, pathogen screening and collection. The goals of this project were; to identify, develop and implement a standardized level of fish health methodologies, develop a common data collection and reporting format in the area of artificial production, evaluate and monitor water quality, improve communications between agencies and provide annual evaluation of fish health information for production of healthier smolts. This completion report will contain a project evaluation, review of the goals of the project, evaluation of the specific fish health analyses, an overview of highlights of the project and concluding remarks. 8 refs., 1 fig., 4 tabs

  14. Photoemission, inverse photoemission and superconducting correlations in Hubbard and t--J ladders: role of the anisotropy between legs and rungs

    OpenAIRE

    Riera, J.; Poilblanc, D.; Dagotto, E.

    1998-01-01

    Several experiments in the context of ladder materials have recently shown that the study of simple models of anisotropic ladders (i.e. with different couplings along legs and rungs) is important for the understanding of these compounds. In this paper Exact Diagonalization studies of the one-band Hubbard and t-J models are reported for a variety of densities, couplings, and anisotropy ratios. The emphasis is given to the one-particle spectral function A(q,\\omega) which prese...

  15. Thinking about going to the dentist: a Contemplation Ladder to assess dentally-avoidant individuals' readiness to go to a dentist

    OpenAIRE

    Hillstead M Blake; Johnson Elissa K; Heima Masahiro; Skaret Erik; Coolidge Trilby; Farjo Nadia; Asmyhr Oyvind; Weinstein Philip

    2011-01-01

    Abstract Background The Transtheoretical Model suggests that individuals vary according to their readiness to change behavior. Previous work in smoking cessation and other health areas suggests that interventions are more successful when they are tailored to an individual's stage of change with regards to the specific behavior. We report on the performance of a single-item measure ("Ladder") to assess the readiness to change dental-avoidant behavior. Methods An existing Contemplation Ladder f...

  16. CO-Selenium in fish tissue: Prediction equations for conversion between whole body, muscle, and eggs

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The lower Gunnison River and the Colorado River are designated critical habitat for two endangered fish species: the Colorado pikeminnow Ptychocheilus lucius and...

  17. Landbird Monitoring Protocol for the U.S. Fish and Wildlife Service, Midwest and Northeast Regions

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This protocol is a standardized tool for monitoring breeding landbirds by use of point counts and was designed for use in U.S. Fish and Wildlife Service FWS Regions...

  18. Walking on the Ladder: 125 GeV Technidilaton, or Conformal Higgs -Dedicated to the late Professor Yoichiro Nambu-

    CERN Document Server

    Matsuzaki, Shinya

    2015-01-01

    The walking technicolor based on the ladder Schwinger-Dyson gap equation is studied, with the scale-invariant coupling being an idealization of the Caswell-Banks-Zaks infrared fixed point in the "anti-Veneziano limit", such that $N_C \\rightarrow \\infty$ with $N_C \\cdot \\alpha(\\mu^2)=$ fixed and $N_F/N_C=$ fixed ($\\gg 1$), of the $SU(N_C)$ gauge theory with massless $N_F$ flavors near criticality. We show that the 125 GeV Higgs can be naturally identified with the technidilaton (TD) predicted in the walking technicolor, a pseudo Nambu-Goldstone (NG) boson of the spontaneous symmetry breaking of the approximate scale symmetry. Ladder calculations yield the TD mass $M_\\phi$ from the trace anomaly as $M_\\phi^2 F_\\phi^2= -4 \\langle \\theta_\\mu^\\mu \\rangle = - \\frac{\\beta(\\alpha (\\mu^2))}{\\alpha(\\mu^2)}\\, \\langle G_{\\lambda \

  19. Columbia River ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, anadromous, and freshwater fish species in Columbia River. Vector polygons in this...

  20. American Samoa ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for reef, pelagic, benthic, and estuarine fish species in American Samoa. Vector polygons in this data set...

  1. North Slope, Alaska ESI: FISH (Fish Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains sensitive biological resource data for marine, estuarine, anadromous, and freshwater fish species for the North Slope of Alaska. Vector...

  2. Yakima Basin Fish Passage Project, Phase 2

    Energy Technology Data Exchange (ETDEWEB)

    1991-08-01

    Implementation of the Yakima Basin Fish Passage Project -- Phase 2 would significantly improve the production of anadromous fish in the Yakima River system. The project would provide offsite mitigation and help to compensate for lower Columbia River hydroelectric fishery losses. The Phase 2 screens would allow greater numbers of juvenile anadromous fish to survive. As a consequence, there would be higher returns of adult salmon and steelhead to the Yakima River. The proposed action would play an integral part in the overall Yakima River anadromous fish enhancement program (fish passage improvement, habitat enhancement, hatchery production increases, and harvest management). These would be environmental benefits associated with implementation of the Fish Passage and Protective Facilities Phase 2 Project. Based on the evaluation presented in this assessment, there would be no significant adverse environmental impacts if the proposed action was carried forward. No significant adverse environmental effects have been identified from construction and operation of the Yakima Phase 2 fish passage project. Proper design and implementation of the project will ensure no adverse effects will occur. Based on the information in this environmental analysis, BPA's and Reclamation's proposal to construct these facilities does not constitute a major Federal action that could significantly affect the quality of the human environment. 8 refs., 4 figs., 6 tabs.

  3. Yakima Basin Fish Passage Project, Phase 2

    International Nuclear Information System (INIS)

    Implementation of the Yakima Basin Fish Passage Project -- Phase 2 would significantly improve the production of anadromous fish in the Yakima River system. The project would provide offsite mitigation and help to compensate for lower Columbia River hydroelectric fishery losses. The Phase 2 screens would allow greater numbers of juvenile anadromous fish to survive. As a consequence, there would be higher returns of adult salmon and steelhead to the Yakima River. The proposed action would play an integral part in the overall Yakima River anadromous fish enhancement program (fish passage improvement, habitat enhancement, hatchery production increases, and harvest management). These would be environmental benefits associated with implementation of the Fish Passage and Protective Facilities Phase 2 Project. Based on the evaluation presented in this assessment, there would be no significant adverse environmental impacts if the proposed action was carried forward. No significant adverse environmental effects have been identified from construction and operation of the Yakima Phase 2 fish passage project. Proper design and implementation of the project will ensure no adverse effects will occur. Based on the information in this environmental analysis, BPA's and Reclamation's proposal to construct these facilities does not constitute a major Federal action that could significantly affect the quality of the human environment. 8 refs., 4 figs., 6 tabs

  4. Motivation Profiles of Online Poker Players and the Role of Interface Preferences: A Laddering Study among Amateur and (Semi-) Professionals

    OpenAIRE

    Zaman, Bieke; Geurden, K.; De Cock, Rozane; Schutter, B. de; Vanden Abeele, Vero

    2014-01-01

    Online Poker has become an increasingly popular form of gambling. In general, this topic has been investigated quantitatively whereby the addictive aspects of online gambling have been compared with the impact of its offline counterpart. In this study, the qualitative method of laddering interviews based on means-end chain theory was used to offer new insights in the online Poker players' psychological motives, and their Poker website's interface preferences. We recruited 18 Belgian young adu...

  5. Longitudinal and Transverse Zeeman Ladders in the Ising-Like Chain Antiferromagnet BaCo2V2O8

    OpenAIRE

    Grenier, B.; Petit, S.; Simonet, V; regnault, L. -P.; Canévet, E.; Raymond, S.; Canals, B.; Berthier, C.; Lejay, P

    2014-01-01

    We explore the spin dynamics emerging from the N\\'eel phase of the chain compound antiferromagnet BaCo2V2O8. Our inelastic neutron scattering study reveals unconventional discrete spin excitations, so called Zeeman ladders, understood in terms of spinon confinement, due to the interchain attractive linear potential. These excitations consist in two interlaced series of modes, respectively with transverse and longitudinal polarization. The latter have no classical counterpart...

  6. Design

    Science.gov (United States)

    Buchanan, Richard; Cross, Nigel; Durling, David; Nelson, Harold; Owen, Charles; Valtonen, Anna; Boling, Elizabeth; Gibbons, Andrew; Visscher-Voerman, Irene

    2013-01-01

    Scholars representing the field of design were asked to identify what they considered to be the most exciting and imaginative work currently being done in their field, as well as how that work might change our understanding. The scholars included Richard Buchanan, Nigel Cross, David Durling, Harold Nelson, Charles Owen, and Anna Valtonen. Scholars…

  7. Star formation relations and CO spectral line energy distributions across the J-ladder and redshift

    International Nuclear Information System (INIS)

    We present FIR [50-300 ?m]–CO luminosity relations (i.e., log LFIR=?log LCO?+?) for the full CO rotational ladder from J = 1-0 up to J = 13-12 for a sample of 62 local (z ? 0.1) (Ultra) Luminous Infrared Galaxies (LIRGs; L IR[8-1000 ?m] > 1011 L ?) using data from Herschel SPIRE-FTS and ground-based telescopes. We extend our sample to high redshifts (z > 1) by including 35 submillimeter selected dusty star forming galaxies from the literature with robust CO observations, and sufficiently well-sampled FIR/submillimeter spectral energy distributions (SEDs), so that accurate FIR luminosities can be determined. The addition of luminous starbursts at high redshifts enlarge the range of the FIR–CO luminosity relations toward the high-IR-luminosity end, while also significantly increasing the small amount of mid-J/high-J CO line data (J = 5-4 and higher) that was available prior to Herschel. This new data set (both in terms of IR luminosity and J-ladder) reveals linear FIR–CO luminosity relations (i.e., ? ? 1) for J = 1-0 up to J = 5-4, with a nearly constant normalization (? ? 2). In the simplest physical scenario, this is expected from the (also) linear FIR–(molecular line) relations recently found for the dense gas tracer lines (HCN and CS), as long as the dense gas mass fraction does not vary strongly within our (merger/starburst)-dominated sample. However, from J = 6-5 and up to the J = 13-12 transition, we find an increasingly sublinear slope and higher normalization constant with increasing J. We argue that these are caused by a warm (?100 K) and dense (>104 cm–3) gas component whose thermal state is unlikely to be maintained by star-formation-powered far-UV radiation fields (and thus is no longer directly tied to the star formation rate). We suggest that mechanical heating (e.g., supernova-driven turbulence and shocks), and not cosmic rays, is the more likely source of energy for this component. The global CO spectral line energy distributions, which remain highly excited from J = 6-5 up to J = 13-12, are found to be a generic feature of the (U)LIRGs in our sample, and further support the presence of this gas component.

  8. Star formation relations and CO spectral line energy distributions across the J-ladder and redshift

    Energy Technology Data Exchange (ETDEWEB)

    Greve, T. R. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Leonidaki, I.; Xilouris, E. M. [Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, GR-15236 Penteli (Greece); Weiß, A.; Henkel, C. [Max-Planck-Institut fur Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Zhang, Z.-Y. [UK Astronomy Technology Centre, Science and Technology Facilities Council, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Van der Werf, P.; Meijerink, R. [Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden (Netherlands); Aalto, S. [Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Observatory, 43994 Onsala (Sweden); Armus, L.; Díaz-Santos, T. [Spitzer Science Center, California Institute of Technology, MS 220-6, Pasadena, CA 91125 (United States); Evans, A. S. [Astronomy Department, University of Virginia Charlottesville, VA 22904 (United States); Fischer, J. [Naval Research Laboratory, Remote Sensing Division, 4555 Overlook Avenue SW, Washington, DC 20375 (United States); Gao, Y. [Purple Mountain Observatory, Chinese Academy of Sciences, 2 West Beijing Road, Nanjing 210008 (China); González-Alfonso, E. [Universidad de Alcala de Henares, Departamento de F?ica, Campus Universitario, E-28871 Alcalá de Henares, Madrid (Spain); Harris, A. [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Naylor, D. A. [Institute for Space Imaging Science, Department of Physics and Astronomy, University of Lethbridge, Lethbridge, AB T1K 3M4 (Canada); Smith, H. A. [Harvard Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Spaans, M., E-mail: t.greve@ucl.ac.uk [Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV Groningen (Netherlands); and others

    2014-10-20

    We present FIR [50-300 ?m]–CO luminosity relations (i.e., log L{sub FIR}=?log L{sub CO}{sup ?}+?) for the full CO rotational ladder from J = 1-0 up to J = 13-12 for a sample of 62 local (z ? 0.1) (Ultra) Luminous Infrared Galaxies (LIRGs; L {sub IR[8-1000} {sub ?m]} > 10{sup 11} L {sub ?}) using data from Herschel SPIRE-FTS and ground-based telescopes. We extend our sample to high redshifts (z > 1) by including 35 submillimeter selected dusty star forming galaxies from the literature with robust CO observations, and sufficiently well-sampled FIR/submillimeter spectral energy distributions (SEDs), so that accurate FIR luminosities can be determined. The addition of luminous starbursts at high redshifts enlarge the range of the FIR–CO luminosity relations toward the high-IR-luminosity end, while also significantly increasing the small amount of mid-J/high-J CO line data (J = 5-4 and higher) that was available prior to Herschel. This new data set (both in terms of IR luminosity and J-ladder) reveals linear FIR–CO luminosity relations (i.e., ? ? 1) for J = 1-0 up to J = 5-4, with a nearly constant normalization (? ? 2). In the simplest physical scenario, this is expected from the (also) linear FIR–(molecular line) relations recently found for the dense gas tracer lines (HCN and CS), as long as the dense gas mass fraction does not vary strongly within our (merger/starburst)-dominated sample. However, from J = 6-5 and up to the J = 13-12 transition, we find an increasingly sublinear slope and higher normalization constant with increasing J. We argue that these are caused by a warm (?100 K) and dense (>10{sup 4} cm{sup –3}) gas component whose thermal state is unlikely to be maintained by star-formation-powered far-UV radiation fields (and thus is no longer directly tied to the star formation rate). We suggest that mechanical heating (e.g., supernova-driven turbulence and shocks), and not cosmic rays, is the more likely source of energy for this component. The global CO spectral line energy distributions, which remain highly excited from J = 6-5 up to J = 13-12, are found to be a generic feature of the (U)LIRGs in our sample, and further support the presence of this gas component.

  9. Synthesis and characterization of polyimide copolymers containing ladder-like polysiloxane

    Science.gov (United States)

    Feng, Linqian

    This research is focused on the synthesis, development, analysis and evaluation of properties of polyurea-b-polyimide (PUI) copolymers containing ladder-like polysiloxane. PUI block copolymers were successfully synthesized by condensation polymerization methods. The structure and properties of the copolymers were controlled by controlling the (i) co-monomer concentration and (ii) curing temperature. Thermally controlled self-assembly of semi-crystalline copolymers occurred at higher annealing temperatures T ? 150°C, resulting in remarkable enhancement in their thermomechanical properties. The observed improvement in the structure and mechanical properties of the copolymers annealed at higher temperature is believed to be due to the development of inter and intra-hydrogen bonding interactions between adjacent copolymer chains. The dynamic mechanical property of the copolymers was determined by dynamic mechanical analysis (DMA) using solution cast thin films. Fourier transform infrared spectroscopy, FTIR and Wide angle X-ray diffraction (WAXD) method were used to study the composition and structure of the copolymers. The presence of hydrogen-bonded (H-bonded) polyimide units in the copolymer resulted in a significant enhancement in the corrosion protection of aluminum alloy 2024-T3. The corrosion performance of PUI coatings was studied by direct current polarization method (DCP) and electrochemical impedance spectroscopy (EIS) in a 3.5wt% NaCl solution. Corrosion performance was remarkably increased by increasing (i) polyurea concentration and (ii) annealing temperature. The coating lifetime was evaluated by using information from time-based Bode plot as well as gravimetric weight gain analysis. The surface energy and diffusivity of PUI copolymers were remarkably decreased as polyurea concentration increased. Semi-crystalline ladder-like polysiloxanes (LPS) containing both mercapto and fluoride side groups were synthesized by using both the sol-gel and monomer self-assembly methods. Subsequently, LPS was incorporated into PUI copolymer followed by imidization. It was shown that full imidization can be achieved at a relatively low temperature of 150°C. It was also shown that the presence of LPS in the copolymer significantly decreased the surface energy, improved the damping ability and thermal dimensional stability of the thin films.

  10. Design

    DEFF Research Database (Denmark)

    Volf, Mette

    2009-01-01

    Design - proces og metode går bag om designerens arbejde og giver et indblik i den skabelsesproces, som designeren er involveret i. Bogen er enestående, fordi den fokuserer på processens flygtige og komplekse karakter, afmystificerer den og gør den operationel - uden at fjerne dens magi. Ud over at beskrive arbejdsmetoder, designprocessen og designerens kontekst inddrager bogen også cases fra anerkendte designvirksomheder, der lader læseren komme tæt på.

  11. From Fishing to Fish Processing: Separation of Fish from Crustaceans in the Norway Lobster-Directed Multispecies Trawl Fishery Improves Seafood Quality

    Science.gov (United States)

    Karlsen, Junita D.; Krag, Ludvig Ahm; Albertsen, Christoffer Moesgaard; Frandsen, Rikke Petri

    2015-01-01

    Fishing gears have negative impacts on seafood quality, especially on fish in the mixed trawl fishery targeting Norway lobster (Nephrops norvegicus). In this fishery, which is worth about €80 millions in Denmark alone, the quality of fish can be significantly improved by simple gear changes. A trawl codend divided into an upper and lower codend was designed to separate fish from Norway lobster during the fishing process by encourage fish to swim into the upper codend by using a frame at the entrance of the lower codend. Separate codends for fish and Norway lobster in the same gear provide the opportunity to selectively reduce small low-value fish, which will reduce catch weight and sorting time onboard the vessel. For this horizontally divided test codend and a standard codend, in which the catch was mixed, quality assessments were performed on the same batches of fish during three steps of the value chain: i) aboard the fishing vessel; ii) at the Fishermen’s Collection Central, and iii) in the production plant. Four species of fish and fillets from fish caught in the upper codend of the test codend were of significantly better quality for several of the assessed parameters compared with those caught in the standard codend: i) newly caught fish showed significantly less scale loss and discolourations and had significantly better texture; ii) landed fish had significantly better skin appearance and texture and significantly fewer discolourations; and iii) fillets showed significantly fewer blood spots and had significantly better texture. There were no differences in injuries for newly caught fish or gaping and bruises for fillets between the test and standard codends. The decrease in catch-related damages in the test codend is explained by little contact between fish and animals with hard or spiny surfaces due to successful separation of fish and Norway lobster into the upper and lower codends, respectively, and by lower catch weight in the upper codend of the test codend compared with the standard codend. The decrease in damages may also improve quality indirectly by inflicting less stress to the fish and subsequently give better texture, which offers advantages such as pre-rigor filleting and fresher products for the market. Significant improvements in fish quality can potentially increase the catch value in nationally important fisheries. PMID:26569413

  12. Laboratory studies on the effects of shear on fish: Final report

    Energy Technology Data Exchange (ETDEWEB)

    Neitzel, Duane A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Richmond, M. C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dauble, D. D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mueller, R. P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Moursund, R. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Abernethy, C. S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Guensch, G. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Cada, G. F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2000-09-01

    The overall objective of these studies was to specify an index describing the hydraulic force that fish experience when subjected to a shear environment. Fluid shear is a phenomenon that is important to fish. However, elevated levels of shear may result in strain rates that injure or kill fish. At hydroelectric generating facilities, concerns have been expressed that strain rates associated with passage through turbines, spillways, and fish bypass systems may adversely affect migrating fish. Development of fish-friendly hydroelectric turbines requires knowledge of the physical forces (injury mechanisms) that impact entrained fish and the fish’s tolerance to these forces. It requires up-front, pre-design specifications for the environmental conditions that occur within the turbine system; in other words, determining or assuming conditions known to injure fish will assist engineers in the design of a fish-friendly turbine system. To address the development of biological specifications, this experiment designed and built a test facility where juvenile fish could be subjected to a range of shear environments and quantified their biological response. The test data reported here provide quantified strain rates and the relationship of these forces to direct and indirect biological effects on fish. The study concludes that juvenile salmonids and American shad should survive shear environments where strain rates do not exceed 500 cm/s/cm at a Dy of 1.8 cm. Additional studies are planned with a sensor fish to better link hydraulic conditions found within the laboratory and field environments.

  13. When Is a Fish Not a Fish? Questions Raised by a Nage Life-Form Category

    Directory of Open Access Journals (Sweden)

    Gregory Forth

    2012-06-01

    Full Text Available Speakers of a Central-Malayo-Polynesian language, the Nage inhabit the central region of the eastern Indonesian island of Flores. Their folk taxonomy of animals (ana wa contains three named life-form taxa, one of which is ika, fish. A review of component folk-generic taxa, however, reveals that Nage do not classify five kinds of freshwater fish as ‘fish’ (ika, even though they further apply ika to various marine fish (including sharks and rays as well as to marine mammals. The article considers this peculiarity of Nage folk zoological taxonomy, and how it might affect an understanding of ika as denoting a ‘fish’ life-form taxon. The main conclusion is that the five excluded categories—distinguished largely on morphological and behavioural grounds, and  conveniently designated as the ‘tebhu cluster’, after one of their members—are contrasted primarily with freshwater species which Nage do classify as ‘fish’ (ika. Specified by name as ika lowo (‘river fish’, these are further contrasted with another named folk-intermediate taxon of ‘marine fish’ (ika mesi. From this, it is argued that, as a life-form category, ika should be understood as implicitly including the five members of the ‘tebhu cluster’ as a third, albeit covert, folk-intermediate taxon.

  14. Fish and wildlife surveillance

    International Nuclear Information System (INIS)

    This section of the 1994 Hanford Site Environmental Report summarizes the monitoring of radioactive contaminants in fish and wildlife species that inhabit the Colombia River and Hanford Site. Wildlife have access to areas of the Site containing radioactive contamination, and fish can be exposed to contamination in spring water entering the river along the shoreline. Therefore, samples are collected at various locations annually, generally during the hunting or fishing season, for selected species

  15. Fish and wildlife surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Poston, T.M.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the monitoring of radioactive contaminants in fish and wildlife species that inhabit the Colombia River and Hanford Site. Wildlife have access to areas of the Site containing radioactive contamination, and fish can be exposed to contamination in spring water entering the river along the shoreline. Therefore, samples are collected at various locations annually, generally during the hunting or fishing season, for selected species.

  16. Automated Translation of Safety Critical Application Software Specifications into PLC Ladder Logic

    Science.gov (United States)

    Leucht, Kurt W.; Semmel, Glenn S.

    2008-01-01

    The numerous benefits of automatic application code generation are widely accepted within the software engineering community. A few of these benefits include raising the abstraction level of application programming, shorter product development time, lower maintenance costs, and increased code quality and consistency. Surprisingly, code generation concepts have not yet found wide acceptance and use in the field of programmable logic controller (PLC) software development. Software engineers at the NASA Kennedy Space Center (KSC) recognized the need for PLC code generation while developing their new ground checkout and launch processing system. They developed a process and a prototype software tool that automatically translates a high-level representation or specification of safety critical application software into ladder logic that executes on a PLC. This process and tool are expected to increase the reliability of the PLC code over that which is written manually, and may even lower life-cycle costs and shorten the development schedule of the new control system at KSC. This paper examines the problem domain and discusses the process and software tool that were prototyped by the KSC software engineers.

  17. Four electrons in a two-leg Hubbard ladder: exact ground states

    CERN Document Server

    Kovács, E; Kovacs, Endre; Gulacsi, Zsolt

    2005-01-01

    In the case of a two-leg Hubbard ladder we present a procedure which allows the exact deduction of the ground state for the four particle problem in arbitrary large lattice system, in a tractable manner, which involves only a reduced Hilbert space region containing the ground state. In the presented case, the method leads to nine analytic, linear, and coupled equations providing the ground state. The procedure which is applicable to few particle problems and other systems as well is based on an r-space representation of the wave functions and construction of symmetry adapted orthogonal basis wave vectors describing the Hilbert space region containing the ground state. Once the ground state is deduced, a complete quantum mechanical characterization of the studied state can be given. Since the analytic structure of the ground state becomes visible during the use of the method, its importance is not reduced only to the understanding of theoretical aspects connected to exact descriptions or potential numerical ap...

  18. Ultrafast electronic state conversion at room temperature utilizing hidden state in cuprate ladder system.

    Science.gov (United States)

    Fukaya, R; Okimoto, Y; Kunitomo, M; Onda, K; Ishikawa, T; Koshihara, S; Hashimoto, H; Ishihara, S; Isayama, A; Yui, H; Sasagawa, T

    2015-01-01

    Photo-control of material properties on femto- (10(-15)) and pico- (10(-12)) second timescales at room temperature has been a long-sought goal of materials science. Here we demonstrate a unique ultrafast conversion between the metallic and insulating state and the emergence of a hidden insulating state by tuning the carrier coherence in a wide temperature range in the two-leg ladder superconductor Sr14-xCaxCu24O41 through femtosecond time-resolved reflection spectroscopy. We also propose a theoretical scenario that can explain the experimental results. The calculations indicate that the holes injected by the ultrashort light reduce the coherence among the inherent hole pairs and result in suppression of conductivity, which is opposite to the conventional photocarrier-doping mechanism. By using trains of ultrashort laser pulses, we successively tune the carrier coherence to within 1?picosecond. Control of hole-pair coherence is shown to be a realistic strategy for tuning the electronic state on ultrafast timescales at room temperature. PMID:26481604

  19. Integrable nonlinear ladder system with background-controlled intersite resonant coupling

    International Nuclear Information System (INIS)

    A new spectral problem on one-dimensional lattices is found allowing consistently to support the zero-curvature representation for a wide class of integrable nonlinear ladder systems. The modified recurrence technique for obtaining an infinite set of conservation laws is developed and some basic conserved quantities are explicitly derived. The eigenvalue problems associated with the limiting spectral operator for the special case of rapidly vanishing boundary conditions on Schroedinger-type fields and finite background condition on a concomitant field are solved and the domains of analyticity of Jost functions are presented both analytically and graphically. This particular example shows that the original auxiliary spectral problem is basically of fourth order and must generate a set of four distinct Jost functions that have to be involved in the procedure of inverse scattering transform. Moreover, there exists a critical background value of accompanying field which separates two principally different possibilities in the organization of analyticity domains of Jost functions. This crossover should inevitably lead to qualitative rearrangements in the structure of model solutions. Thus already in the limit of low-amplitude excitations we strictly observe the loss of stability regarding the linear spectrum of Schroedinger subsystem just above the critical background value of practically unexcited concomitant field, whereas in the stability region the structure of linear spectrum is essentially controlled by the magnitude of background level via effective modification of both intersite resonant coupling and self-site coupling

  20. Crystal Structure and Thermoelectric Properties of the Incommensurate Chimney-Ladder Compound VGe? (? ~1.82)

    Science.gov (United States)

    Hamada, Haruki; Kikuchi, Yuta; Hayashi, Kei; Miyazaki, Yuzuru

    2015-09-01

    A single-phase sample of a Nowotny chimney-ladder phase known as V17Ge31 has been prepared and its modulated crystal structure has been determined by means of a (3+1)-dimensional superspace approach. As in the case of higher manganese silicides (HMSs) MnSi?, the compound consists of two tetragonal subsystems of [V] and [Ge] with an irrational c-axis ratio ? = c_{V} /c_{Ge} ˜ 1.82, and hence the structure formula is represented as VGe ? . As expected from the valence electron count estimated from the refined ?, the present germanide exhibits a metallic behavior with the electrical conductivity ? = 6.25 × 103 S/cm and the Seebeck coefficient S = 10.2 ?V/K at 900 K. The resulting thermoelectric power factor of S^2? = 6.56 × 10-5 W/mK2 and the dimensionless figure-of-merit, ZT, = 3.7 × 10-3 at 900 K demonstrate that the germanide is not a promising thermoelectric material. However, as the determined lattice thermal conductivity is comparable to that of HMSs, thermoelectric properties can be maximized through the partial substitution of V with group 6-8 elements to decrease hole carrier concentration.

  1. A Redetermination of the Hubble Constant with the Hubble Space Telescope from a Differential Distance Ladder

    CERN Document Server

    Riess, Adam G; Casertano, Stefano; Sosey, Megan; Lampeitl, Hubert; Ferguson, Henry C; Filippenko, Alexei V; Jha, Saurabh W; Li, Weidong; Chornock, Ryan; Sarkar, Devdeep

    2009-01-01

    We report observations of 240 Cepheid variables obtained with the Near Infrared Camera (NICMOS) through the F160W filter on the Hubble Space Telescope (HST). The Cepheids are distributed across six recent hosts of Type Ia supernovae (SNe Ia) and the "maser galaxy" NGC 4258, allowing us to directly calibrate the peak luminosities of the SNe Ia from the precise, geometric distance measurements provided by the masers. New features of our measurement include the use of the same instrument for all Cepheid measurements across the distance ladder and homogeneity of the Cepheid periods and metallicities thus necessitating only a differential measurement of Cepheid fluxes and reducing the largest systematic uncertainties in the determination of the fiducial SN Ia luminosity. The NICMOS measurements reduce differential extinction in the host galaxies by a factor of 5 over past optical data. Combined with an expanded of 240 SNe Ia at z<0.1 which define their magnitude-redshift relation, we find H_0=74.2 +/-3.6, a 4.8...

  2. (Sr/Ca)_{14}Cu_{24}O_{41} spin ladders studied by NMR under pressure

    CERN Document Server

    Piskunov, Y; Auban-Senzier, P; Wzietek, P; Bourbonnais, C; Ammerhal, U; Dhalenne, G; Revcolevschi, A

    2001-01-01

    (63)Cu-NMR measurements have been performed on two-leg hole-doped spin ladders Sr_{14-x}Ca_{x}Cu_{24}O_{41} single crystals (0-x-12) at several pressures up to the pressure domain where the stabilization of a superconducting ground state can be achieved. The data reveal marked decrease of the spin gap derived from Knight shift measurements upon Ca substitution and also under pressure and confirm the onset of low lying spin excitations around P_{c} as previously reported. The spin gap in Sr_{2}Ca_{12}Cu_{24}O_{41} is strongly reduced above 20 kbar. However, the data of an experiment performed at P=36 kbar where superconductivity has been detected at 6.7K by an inductive technique have shown that a significant amount of spin excitations remains gapped at 80K when superconductivity sets in. The standard relaxation model with two and three-magnon modes explains fairly well the activated relaxation data in the intermediate temperature regime corresponding to gapped spin excitations using the spin gap data derived ...

  3. Femtosecond hot-exciton emission in a ladder-type ?-conjugated rigid-polymer nanowire

    Science.gov (United States)

    Dai, D. C.; Monkman, A. P.

    2013-01-01

    A hot exciton is usually the initial elementary excitation product of the solid phase, particularly in low-dimensional photonic materials, which is a bottleneck to all subsequent processes. Measurement of hot-exciton emission (HExEm) is a great challenge due to fast EK relaxation and thus very weak transient emission. Here, we report the unambiguous observation of femtosecond HExEm from thin films of a model quasi-one-dimensional ?-conjugated organic rigid-rod quantum nanowire, methyl-substituted ladder-type poly(para-phenylenes), using femtosecond time-resolved fluorescence spectroscopy. The results show clear HExEm from the cooling hot excitons, having a lifetime of ˜500 to ˜800 fs, and concomitant very weak density-dependent singlet-singlet annihilation (SSA) due to this ultrashort dwell time. The ultrafast dispersive migration of the relaxing excitons toward the bottom of the density of states occurs immediately after HExEm, which is simultaneous to the strong density-dependent SSA effect enhanced by the lengthening dwell time.

  4. An overview on the phase diagram of the frustrated two-leg ladder model

    CERN Document Server

    Hakobyan, T S; Roger, M

    2001-01-01

    Using Density-Matrix Renormalization Group, we investigate the general phase diagram of the frustrated two-leg ladder with Heisenberg interactions along legs, rungs and diagonals. We confirm that all antiferromagnetic gapped states belong to the same universality class as the Haldane phase. In a three-dimensional phase diagram, we determine a continuous surface with singularities in the string-order parameter or its first derivative, corresponding to a transition between two Haldane phases with different topological order. Some parts of this transition surface are critical with zero gap and vanishing string-order parameter. In the complementary parts, the transition is first order with finite gap and string order. The boundary of this surface with the ferromagnetic region is a critical end line, when the surface is critical and a triple line anywhere else. Part of this boundary coincides with the exactly soluble model proposed by D.V. Dmitriev, V. Ya Krivnov and A.A. Ovchinnikov [Phys. Rev. B 56, 5985 (1997)]...

  5. Transport properties of poly(GACT)–poly(CTGA) deoxyribonucleic acid: A ladder model approach

    Indian Academy of Sciences (India)

    S A Ketabi; A A Fouladi

    2009-06-01

    In this paper, based on the tight-binding Hamiltonian model and within the framework of a generalized Green's function technique, the electronic conduction through the poly(GACT)–poly(CTGA) DNA molecule in SWNT/DNA/SWNT structure has been numerically investigated. In a ladder model, we consider DNA as a planar molecule containing cells and four further sites (two base pair sites and two backbone sites) in each cell, sandwiched between two semi-infinite single-walled carbon nanotubes (SWNT) as the electrodes. Having relied on Landauer formalism, we focussed on studying the current–voltage characteristics of DNA, the effect of the coupling strength of SWNT/DNA interface and the role of tube radius of nanotube contacts on the electronic transmission through the foregoing structure. Finally, a characteristic time was calculated for the electron transmission, which measures the delay caused by the tunnelling through the SWNT/DNA interface. The results clearly show that the calculated characteristic time and also the conductance of the system are sensitive to the coupling strength between DNA molecule and nanotube contacts.

  6. Selective excitation of branched vibrational ladder in uranium hexafluoride laser isotope separation

    International Nuclear Information System (INIS)

    Theoretical investigation was made on the dynamics of initial excitation process in molecular laser isotope separation for uranium hexafluoride (UF6) based on the generalized N-level density-matrix equation derived by Goodman et al. Branched vibrational model due to anharmonic-splitting components for the ?3 mode of UF6 molecule were formalized and phase interferences of density-matrix elements were considered to analyze the selective excitation. Because of a power-broadening effect, no more than 0.05J/cm2 fluence of a laser pulse completely masks high enrichment peaks in broadband (?? = 2GHz) pumping case. Even when matching the laser frequency with ?3 band (n = 0 ? 1) of 238UF6, the enrichment factor (? ? Rproduct/Rfeed, R ? [235UF6]/[238UF6]; R is the abundance ratio and [ ] means the mole fraction.) does not decrease. A narrow spectral linewidth (?? = 400MHz) is shown to be essential to achieve a high concentration ratio in the system with a branched N-level ladder as expected from a general two-level system. The exciting frequency, which does not necessarily accord with the ?3 band of 235UF6, gives the maximum enrichment peak. Both the detuning of the optimum frequency and the sharp enrichment peak suggest a direct excitation due to multiphoton resonance. Spectral stability of the laser pulse is also required to excite only the desired isotope for the system with complicated anharmonic-splittings. (author)

  7. Combating Illegal Fishing

    Directory of Open Access Journals (Sweden)

    Sorin Stanciu

    2010-10-01

    Full Text Available Illegal, unreported and unregulated (IUU fishing is a worldwide phenomenon. Its extent and its environmental,economic and social consequences are such that it has become a priority issue at international level. IUU fishingcontributes to the depletion of fish stocks and jeopardises protection and recovery measures put in place to ensure theviability of resources. It represents unfair competition for those who exploit fish resources legally. The Commissionhave been involved in the fight against IUU fishing for over a decade and in 2002 the Commission adopted an ActionPlan against IUU fishing inspired by the FAOs International Plan of Action to prevent, deter and eliminate IUUfishing of 2001. However, despite regional and international efforts to stop IUU fishing the phenomenon is still agrowing problem and as a result, the European Community intensified its action towards IUU fishing by launching aconsultation process in 2007. A Proposal to prevent, deter and eliminate IUU fishing was adopted in October 2007and a Regulation to prevent, deter and eliminate illegal, unreported and unregulated (IUU fishing was adopted on 29September 2008, after a unanimous political agreement.

  8. Anglers' fishing problem

    CERN Document Server

    Karpowicz, Anna

    2011-01-01

    The considered model will be formulated as related to "the fishing problem" even if the other applications of it are much more obvious. The angler goes fishing. He uses various techniques and he has at most two fishing rods. He buys a fishing ticket for a fixed time. The fishes are caught with the use of different methods according to the renewal processes. The fishes' value and the inter arrival times are given by the sequences of independent, identically distributed (i.i.d.) random variables with the known distribution functions. It forms the marked renewal--reward process. The angler's measure of satisfaction is given by the difference between the utility function, depending on the value of the fishes caught, and the cost function connected with the time of fishing. In this way, the angler's relative opinion about the methods of fishing is modelled. The angler's aim is to have as much satisfaction as possible and additionally he has to leave the lake before a fixed moment. Therefore his goal is to find two...

  9. Intelligent Fish Freshness Assessment

    Directory of Open Access Journals (Sweden)

    Deena Benjamin

    2008-04-01

    Full Text Available Fish species identification and automated fish freshness assessment play important roles in fishery industry applications. This paper describes a method based on support vector machines (SVMs to improve the performance of fish identification systems. The result is used for the assessment of fish freshness using artificial neural network (ANN. Identification of the fish species involves processing of the images of fish. The most efficient features were extracted and combined with the down-sampled version of the images to create a 1D input vector. Max-Win algorithm applied to the SVM-based classifiers has enhanced the reliability of sorting to 96.46%. The realisation of Cyranose 320 Electronic nose (E-nose, in order to evaluate the fish freshness in real-time, is experimented. Intelligent processing of the sensor patterns involves the use of a dedicated ANN for each species under study. The best estimation of freshness was provided by the most sensitive sensors. Data was collected from four selected species of fishes over a period of ten days. It was concluded that the performance can be increased using individual trained ANN for each specie. The proposed system has been successful in identifying the number of days after catching the fish with an accuracy of up to 91%.

  10. Fish silage as feed ingredient for fish and livestock

    OpenAIRE

    Rurangwa, E.; van Vuuren, A. M.; Poelman, M.

    2014-01-01

    The present report analyses through a literature review the potential of fish silage to valorise fish processing by-products into economically relevant protein sources for fish and livestock feed production in East Africa.

  11. Value based segmentation : a study of wild fish versus farmed fish consumption in Nha Trang

    OpenAIRE

    Suneth Jayampathi, R.P.S.

    2010-01-01

    The primary purpose of this study was to identify market segments based on personal values, values and lifestyles, environmental concern, fish welfare concern, ethical concern for fish farming and health involvement. A self-administrated questionnaire was conducted on a convenience sample of 209 Vietnamese consumers. It was designed to investigate consumers’ concern for issues used as segmentation basis together with variables used in profiling the segments. The measurement scales used in thi...

  12. Preventing AVF thrombosis: the rationale and design of the Omega-3 fatty acids (Fish Oils and Aspirin in Vascular access OUtcomes in REnal Disease (FAVOURED study

    Directory of Open Access Journals (Sweden)

    Rosman Johan

    2009-01-01

    Full Text Available Abstract Background Haemodialysis (HD is critically dependent on the availability of adequate access to the systemic circulation, ideally via a native arteriovenous fistula (AVF. The Primary failure rate of an AVF ranges between 20–54%, due to thrombosis or failure of maturation. There remains limited evidence for the use of anti-platelet agents and uncertainty as to choice of agent(s for the prevention of AVF thrombosis. We present the study protocol for a randomised, double-blind, placebo-controlled, clinical trial examining whether the use of the anti-platelet agents, aspirin and omega-3 fatty acids, either alone or in combination, will effectively reduce the risk of early thrombosis in de novo AVF. Methods/Design The study population is adult patients with stage IV or V chronic kidney disease (CKD currently on HD or where HD is planned to start within 6 months in whom a planned upper or lower arm AVF is to be the primary HD access. Using a factorial-design trial, patients will be randomised to aspirin or matching placebo, and also to omega-3 fatty acids or matching placebo, resulting in four treatment groups (aspirin placebo/omega-3 fatty acid placebo, aspirin/omega-3 fatty acid placebo, aspirin placebo/omega-3 fatty acid, aspirin/omega-3 fatty acid. Randomisation will be achieved using a dynamic balancing method over the two stratification factors of study site and upper versus lower arm AVF. The medication will be commenced pre-operatively and continued for 3 months post surgery. The primary outcome is patency of the AVF at three months after randomisation. Secondary outcome measures will include functional patency at six and twelve months, primary patency time, secondary (assisted patency time, and adverse events, particularly bleeding. Discussion This multicentre Australian and New Zealand study has been designed to determine whether the outcome of surgery to create de novo AVF can be improved by the use of aspirin and/or omega-3 fatty acids. Recently a placebo-controlled trial has shown that clopidogrel is effective in safely preventing primary AVF thrombosis, but ineffective at increasing functional patency. Our study presents significant differences in the anti-platelet agents used, the study design, and surgical and patient demographics that should contribute further evidence regarding the efficacy of anti-platelet agents. Trial Registration Australia & New Zealand Clinical Trials Register (ACTRN12607000569404.

  13. DEVICE FOR FISH ADDITIONAL FEEDING ON MOSQUITO LARVAE ?????????? ??? ????????? ???? ????????? ???????

    Directory of Open Access Journals (Sweden)

    Gazalov V. S.

    2013-03-01

    Full Text Available The electro optical transducer with changeable emission color depending on air temperature, which is destined for fish additional feeding with mosquito larvae, has been designed. It is the effective device of electrotechnics of ecological fish additional feeding with live feed

  14. From fishing to fish processing: separation of fish from crustaceans in the Norway lobster-directed multispecies trawl fishery improves seafood quality

    DEFF Research Database (Denmark)

    Karlsen, Junita Diana; Krag, Ludvig Ahm

    2015-01-01

    Fishing gears have negative impacts on seafood quality, especially on fish in the mixed trawl fishery targeting Norway lobster (Nephrops norvegicus). In this fishery, which is worth about €80 millions in Denmark alone, the quality of fish can be significantly improved by simple gear changes. A trawl codend divided into an upper and lower codend was designed to separate fish from Norway lobster during the fishing process by encourage fish to swim into the upper codend by using a frame at the entrance of the lower codend. Separate codends for fish and Norway lobster in the same gear provide the opportunity to selectively reduce small low-value fish, which will reduce catch weight and sorting time onboard the vessel. For this horizontally divided test codend and a standard codend, in which the catch was mixed, quality assessments were performed on the same batches of fish during three steps of the value chain: i) aboard the fishing vessel; ii) at the Fishermen’s Collection Central, and iii) in the production plant. Four species of fish and fillets from fish caught in the upper codend of the test codend were of significantly better quality for several of the assessed parameters compared with those caught in the standard codend: i) newly caught fish showed significantly less scale loss and discolourations and had significantly better texture; ii) landed fish had significantly better skin appearance and texture and significantly fewer discolourations; and iii) fillets showed significantly fewer blood spots and had significantly better texture. There were no differences in injuries for newly caught fish or gaping and bruises for fillets between the test and standard codends. The decrease in catch-related damages in the test codend is explained by little contact between fish and animals with hard or spiny surfaces due to successful separation of fish and Norway lobster into the upper and lower codends, respectively, and by lower catch weight in the upper codend of the test codend compared with the standard codend. The decrease in damages may also improve quality indirectly by inflicting less stress to the fish and subsequently give better texture, which offers advantages such as pre-rigor filleting and fresher products for the market

  15. Biannual Fish Survey, Spring 1993

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The biannual fish survey was initiated in 1989 to monitor population trends of federally endangered fish species at Ash Meadows National Wildlife Refuge. Item 421...

  16. Design of Studies for Development of BPA Fish and Wildlife Mitigation Accounting Policy Phase II, Volume I, 1985-1988 Summary Report.

    Energy Technology Data Exchange (ETDEWEB)

    Kneese, Allen V.

    1988-08-01

    As the mitigation prescribed by the Regional Act proceeds, the incremental costs of corrective measures to lessen the environmental impacts of the hydroelectric system are expected to increase and difficult questions to arise about the costs, effectiveness, and justification of alternative measures and their systemwide implications. It was deemed prudent by the BPA to anticipate this situation by launching a forward-looking research program aimed at providing methodological tools and data suitable for estimating the productivity and cost implications of mitigation alternatives in a timely manner with state-of-the-art accuracy. In this spirit, Resources for the Future (RFF) agreed at the request of the BPA to develop a research program which would provide an analytical system designed to assist the BPA Administrator and other interested and responsible parties in evaluating the ecological and economic aspects of alternative protection, enhancement, and mitigation measures. 12 refs., 4 figs., 1 tab.

  17. Fishing penetration injuries

    OpenAIRE

    Dudkiewicz, I; Salai, M; Blankstein, A.; Chechik, A.

    2000-01-01

    Background—Fishing involves millions of people throughout the world and is considered a pleasant and harmless sport. However, many kinds of injury can occur. Penetrating injuries to the extremities by fishing equipment such as hooks and harpoons, and even by scales, or infection from penetration of scales etc are relatively common although hardly ever reported in the literature.

  18. Folkbiology of Freshwater Fish

    Science.gov (United States)

    Medin, Douglas L.; Ross, Norbert O.; Atran, Scott; Cox, Douglas; Coley, John; Proffitt, Julia B.; Blok, Sergey

    2006-01-01

    Cross-cultural comparisons of categorization often confound cultural factors with expertise. This paper reports four experiments on the conceptual behavior of Native American and majority-culture fish experts. The two groups live in the same general area and engage in essentially the same set of fishing-related behaviors. Nonetheless, cultural…

  19. Distance from a fishing community explains fish abundance in a no-take zone with weak compliance.

    Science.gov (United States)

    Advani, Sahir; Rix, Laura N; Aherne, Danielle M; Alwany, Magdy A; Bailey, David M

    2015-01-01

    There are numerous examples of no-take marine reserves effectively conserving fish stocks within their boundaries. However, no-take reserves can be rendered ineffective and turned into 'paper parks' through poor compliance and weak enforcement of reserve regulations. Long-term monitoring is thus essential to assess the effectiveness of marine reserves in meeting conservation and management objectives. This study documents the present state of the 15-year old no-take zone (NTZ) of South El Ghargana within the Nabq Managed Resource Protected Area, South Sinai, Egyptian Red Sea. Previous studies credited willing compliance by the local fishing community for the increased abundances of targeted fish within the designated NTZ boundaries compared to adjacent fished or take-zones. We compared benthic habitat and fish abundance within the NTZ and the adjacent take sites open to fishing, but found no significant effect of the reserve. Instead, the strongest evidence was for a simple negative relationship between fishing pressure and distance from the closest fishing village. The abundance of targeted piscivorous fish increased significantly with increasing distance from the village, while herbivorous fish showed the opposite trend. This gradient was supported by a corresponding negative correlation between the amount of discarded fishing gear observed on the reef and increasing distance from the village. Discarded fishing gear within the NTZ suggested decreased compliance with the no-take regulations. Our findings indicate that due to non-compliance the no-take reserve is no longer functioning effectively, despite its apparent initial successes and instead a gradient of fishing pressure exists with distance from the nearest fishing community. PMID:25950815

  20. Antimicrobial Peptides from Fish

    Directory of Open Access Journals (Sweden)

    Jorge A. Masso-Silva

    2014-03-01

    Full Text Available Antimicrobial peptides (AMPs are found widely distributed through Nature, and participate in the innate host defense of each species. Fish are a great source of these peptides, as they express all of the major classes of AMPs, including defensins, cathelicidins, hepcidins, histone-derived peptides, and a fish-specific class of the cecropin family, called piscidins. As with other species, the fish peptides exhibit broad-spectrum antimicrobial activity, killing both fish and human pathogens. They are also immunomodulatory, and their genes are highly responsive to microbes and innate immuno-stimulatory molecules. Recent research has demonstrated that some of the unique properties of fish peptides, including their ability to act even in very high salt concentrations, make them good potential targets for development as therapeutic antimicrobials. Further, the stimulation of their gene expression by exogenous factors could be useful in preventing pathogenic microbes in aquaculture.

  1. Effects of radiations on ornamental fish

    International Nuclear Information System (INIS)

    Radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiations: ionizing and non-ionizing. Ultraviolet, X-rays, and gamma rays are some examples of radiation. 'Ornamental fish' is designed for aquatic hobbyists and the aquatic industry for several purposes. UV light has two primary uses in fish culture: Controlling green water and disinfecting the water supply. Many proponents of UV disinfection sometimes overlook the additional benefits relating to ornamental fish; those being that cleaner water reduces the stress on the fish by not having to fight off diseases, thus enhancing its immune system and leading to faster growth and more brilliant colors. Ultraviolet sterilizers are often used in aquaria to help control unwanted microorganisms in the water. UV radiation also ensures that exposed pathogens cannot reproduce, thus decreasing the likelihood of a disease outbreak in an aquarium. Despite of these benefits, the ill-effects of radiations cannot be ruled out. Ultraviolet Radiation-induced DNA Damage is seen in the skin of the Platyfish Xiphophorus. Higher radiation doses may cause the gastrointestinal syndrome that leads to defects of the intestinal mucosa barrier with successive contamination of musculature. Exposure to UV radiation can kill the fish and induce sublethal effects in embryos, larvae and adults. The change in skin includes irregularity of skin surface, epidermal oedema, necrosis etc. Irradiation may badly influence the textural attributes of fish muscle. (author)

  2. Present scenario of landing and distribution of fish in Bangladesh.

    Science.gov (United States)

    Rahman, M; Khatun, S; Hossain, M B; Hassan, M N; Nowsad, A A K M

    2013-11-15

    The present study was designed to know the landing and distribution pathways of fish and types and nature of stakeholders involved in fish distribution chain in Bangladesh. A total of 237 fish landing centers and 5440 markets were detected. The number of landing center and market were highest in Chittagong and Dhaka division respectively. Stakeholders in fish distribution, viz., arotdars, paikers and retailers were found to be 6219, 39506 and 122922, respectively. A 84.71% of the landing centers were found to be operated year round while 15.29% were seasonal. The major fish production zones and major gateways of the country where inland capture and culture and marine capture fish landed were identified. In any locality 62.83% of the landed fish were transported within 100 km area and 5.73% of fish were transported beyond 500 km. The quantity of fish harvested from river, beel, Kaptai lake floodplain, pond, baor, coastal area/sea and shrimp/prawn farm were 5.25, 4.41, 0.13, 35.03, 38.22, 0.23, 10.93 and 5.80%, respectively. The common constraints identified were lack of adequate infrastructure facilities in the landing center and market, unhygienic environment, influence of middlemen, money lending at high rate etc. For the betterment of fish landing and distribution, appropriate authority should pay proper attention so that both quality and fair price are ensured. PMID:24511690

  3. Present Scenario of Landing and Distribution of Fish in Bangladesh

    Directory of Open Access Journals (Sweden)

    A.A.K.M. Nowsad

    2013-01-01

    Full Text Available The present study was designed to know the landing and distribution pathways of fish and types and nature of stakeholders involved in fish distribution chain in Bangladesh. A total of 237 fish landing centers and 5440 markets were detected. The number of landing center and market were highest in Chittagong and Dhaka division respectively. Stakeholders in fish distribution, viz., arotdars, paikers and retailers were found to be 6219, 39506 and 122922, respectively. A 84.71% of the landing centers were found to be operated year round while 15.29% were seasonal. The major fish production zones and major gateways of the country where inland capture and culture and marine capture fish landed were identified. In any locality 62.83% of the landed fish were transported within 100 km area and 5.73% of fish were transported beyond 500 km. The quantity of fish harvested from river, beel, Kaptai lake floodplain, pond, baor, coastal area/sea and shrimp/prawn farm were 5.25, 4.41, 0.13, 35.03, 38.22, 0.23, 10.93 and 5.80%, respectively. The common constraints identified were lack of adequate infrastructure facilities in the landing center and market, unhygienic environment, influence of middlemen, money lending at high rate etc. For the betterment of fish landing and distribution, appropriate authority should pay proper attention so that both quality and fair price are ensured.

  4. Design of Studies for Development of BPA Fish and Wildlife Mitigation Accounting Policy Phase II, Volume II, 1985-1988 Technical Report.

    Energy Technology Data Exchange (ETDEWEB)

    Kneese, Allen V.

    1988-08-01

    The incremental costs of corrective measures to lessen the environmental impacts of the hydroelectric system are expected to increase and difficult questions to arise about the costs, effectiveness, and justification of alternative measures and their systemwide implications. The BPA anticipate this situation by launching a forward-looking research program aimed at providing methodological tools and data suitable for estimating the productivity and cost implications of mitigation alternatives in a timely manner with state-of-the-art accuracy. Resources for the Future (RFF) agreed at the request of the BPA to develop a research program which would provide an analytical system designed to assist the BPA Administrator and other interested and responsible parties in evaluating the ecological and economic aspects of alternative protection, enhancement, and mitigation measures. While this progression from an ecological understanding to cost-effectiveness analyses is straightforward in concept, the complexities of the Columbia River system make the development of analytical methods far from simple in practice. The Phase 2 final report outlines the technical issues involved in developing an analytical system and proposes a program of research to address these issues. The report is presented in the Summary Report (Volume 1), and the present volume which consists of three technical reports: Part I, Modeling the Salmon and Steelhead Fisheries of the Columbia River Basin; Part II, Models for Cost-Effectiveness Analysis; and Part III, Ocean Fisheries Harvest Management.

  5. Calibrating the cosmic distance scale ladder: the role of the sound-horizon scale and the local expansion rate as distance anchors

    Science.gov (United States)

    Cuesta, Antonio J.; Verde, Licia; Riess, Adam; Jimenez, Raul

    2015-04-01

    We exploit cosmological model-independent measurements of the expansion history of the Universe to provide a cosmic distance ladder. These are supernovae Type Ia used as standard candles (at redshift between 0.01 and 1.3) and baryon acoustic oscillations (at redshifts between 0.1 and 0.8) as standard rulers. We calibrate (anchor) the ladder in two ways: first using the local H0 value as an anchor at z = 0 (effectively calibrating the standard candles) and secondly using the cosmic microwave background-inferred sound-horizon scale as an anchor (giving the standard ruler length) as an inverse distance ladder. Both methods are consistent, but the uncertainty in the expansion history H(z) is smaller if the sound-horizon scale is used. We present inferred values for the sound horizon at radiation drag rd which do not rely on assumptions about the early expansion history nor on cosmic microwave background measurements but on the cosmic distance ladder and baryon acoustic oscillations measurements. We also present derived values of H0 from the inverse distance ladder and we show that they are in very good agreement with the extrapolated value in a ? cold dark matter model from Planck cosmic microwave background data.

  6. Design criteria for offshore feed barges

    OpenAIRE

    Mathisen, Sindre

    2012-01-01

    The fish farming industry faces some problems for the future as the escaping of fish and fish lice. One solution to these problems could be to move the farms further offshore. The main focus of the industry is on the cages the fish is held in, but the feed barge is the brain of a fish farm. Before offshore fish farming is an acceptable solution for the future the design criteria for the feed barge has to be sufficient for more exposed areas.Some regulations both for fish farming and the oil i...

  7. Framing Prospective Elementary Teachers' Conceptions of Dissolving as a Ladder of Explanations

    Science.gov (United States)

    Subramaniam, Karthigeyan; Esprivalo Harrell, Pamela

    2013-11-01

    The paper details an exploratory qualitative study that investigated 61 prospective teachers' conceptual understanding of dissolving salt and sugar in water respectively. The study was set within a 15-week elementary science methods course that included a 5E learning cycle lesson on dissolving, the instructional context. Oversby's (Prim Sci Rev 63:6-19, 2002, Aspects of teaching secondary science, Routledge Falmer, London, 2002) ladder of explanations for the context of dissolving, current scientific explanations for dissolving and perspectives on conceptions and misconceptions provided the unified framework for the study. Concept maps, interview transcripts, written artifacts, and drawings and narratives were used as data to investigate these prospective teachers' conceptual understanding of dissolving throughout the 15-weeks of the methods course. Analysis revealed that participants' explanations of dissolving were predominantly descriptive explanations (39 %) and interpretative explanations (38 %), with lower percentage occurrences of intentional (14 %) and cause and effect (9 %) level explanations. Most of these explanations were also constructed by a set of loosely connected and reinforcing everyday concepts abstracted from common everyday experiences making them misconceptions. Implications include: (1) the need for science teacher educators to use multiple platforms to derive their prospective elementary teachers' conceptual understandings of science content; and (2) to identify and help them identify their own scientific conceptions and misconceptions and how they influence the construction of scientific/nonscientific explanations. Science teacher educators also need to emphasize the role of meaningful frameworks associated with the concept that is being introduced during the Engage phase of the 5E learning cycle. This is important because, relevant prior knowledge is associated with the knowledge of the particle theory of matter and both are part of larger knowledge system comprised of interrelated scientific concepts.

  8. Modeling Fish Growth in Low Dissolved Oxygen

    Science.gov (United States)

    Neilan, Rachael Miller

    2013-01-01

    This article describes a computational project designed for undergraduate students as an introduction to mathematical modeling. Students use an ordinary differential equation to describe fish weight and assume the instantaneous growth rate depends on the concentration of dissolved oxygen. Published laboratory experiments suggest that continuous…

  9. 50 CFR 71.11 - Opening of national fish hatchery areas to fishing.

    Science.gov (United States)

    2010-10-01

    ... Opening of national fish hatchery areas to fishing. 71.11 Section 71.11 Wildlife and...OF FISHERIES CONSERVATION AREAS HUNTING AND FISHING ON NATIONAL FISH HATCHERY AREAS Fishing § 71.11 Opening of national fish...

  10. COMBO-FISH Enables High Precision Localization Microscopy as a Prerequisite for Nanostructure Analysis of Genome Loci

    OpenAIRE

    Rainer Kaufmann; Christoph Cremer; Jörg Hoheisel; Anette Jacob; Eberhard Schmitt; Patrick Müller; Michael Hausmann

    2010-01-01

    With the completeness of genome databases, it has become possible to develop a novel FISH (Fluorescence in Situ Hybridization) technique called COMBO-FISH (COMBinatorial Oligo FISH). In contrast to other FISH techniques, COMBO-FISH makes use of a bioinformatics approach for probe set design. By means of computer genome database searching, several oligonucleotide stretches of typical lengths of 15–30 nucleotides are selected in such a way that all uniquely colocalize at the given genome target...

  11. Which Fish Should I Eat? Perspectives Influencing Fish Consumption Choices

    OpenAIRE

    Karagas, Margaret R.; Mariën, Koenraad; Rheinberger, Christoph M.; Schoeny, Rita; Oken, Emily; Choi, Anna Lai; Korrick, Susan Abigail; Sunderland, Elsie

    2012-01-01

    Background: Diverse perspectives have influenced fish consumption choices. Objectives: We summarized the issue of fish consumption choice from toxicological, nutritional, ecological, and economic points of view; identified areas of overlap and disagreement among these viewpoints; and reviewed effects of previous fish consumption advisories. Methods: We reviewed published scientific literature, public health guidelines, and advisories related to fish consumption, focusing on advisories targete...

  12. 49 CFR 173.218 - Fish meal or fish scrap.

    Science.gov (United States)

    2010-10-01

    ...Transportation 2 2010-10-01 2010-10-01 false Fish meal or fish scrap. 173.218 Section 173.218 Transportation...Materials Other Than Class 1 and Class 7 § 173.218 Fish meal or fish scrap. (a) Except as provided in...

  13. On the use of a risk ladder: Linking public perception of risks associated with indoor air with cognitive elements and attitudes toward risk reduction

    Science.gov (United States)

    Moschandreas, D. J.; Chang, P. E.

    In recent years a number of building managers have invested small amounts of money to measure indoor air quality in offices and other non-industrial buildings. Their objective is to reduce the number of occupant complaints, and not necessarily to reduce the risk associated with such complaints. Clearly, reduction of the risk would require greater investment of funds and effort. This paper focuses on individuals and the amount of money they are willing to invest in order to reduce risks associated with indoor air pollution in their home. Psychologists assert that lay judgement of risks are influenced by cognitive biases and attitudes. This study investigates the possibility that cognitive elements and general attitudes influence not only the perceived risk associated with exposures to indoor air pollutants, but also the willingness of individuals to invest in order to reduce the risk. A three-stage study was performed to determine some of the factors that influence public decisions to control the quality of the air inside their home. The study is focused on the design of a risk ladder, and the survey of 400 randomly selected individuals in the Chicago metropolitan area. The survey was designed to determine if demographics, smoking, education, or income influence the desire of individuals to invest in order to reduce indoor air pollution. The following conclusions were reached: (i) public awareness of indoor air pollution is high; (ii) media campaigns on indoor air pollution affect the determination of the specific pollutant the public perceives as important, but do not influence the public's desire to invest larger amounts of money to reduce risks from exposures to air pollutants in the residential environment; (iii) the public is not willing to spend large amounts of money to reduce indoor residential air pollution; (iv) education does not affect the level of awareness regarding indoor air pollution, but it increases the willingness to invest in an effort to reduce indoor air pollution; and (v) smoking status does not affect any of the above.

  14. Why do fish school?

    Directory of Open Access Journals (Sweden)

    Matz LARSSON

    2012-02-01

    Full Text Available Synchronized movements (schooling emit complex and overlapping sound and pressure curves that might confuse the inner ear and lateral line organ (LLO of a predator. Moreover, prey-fish moving close to each other may blur the electro-sensory perception of predators. The aim of this review is to explore mechanisms associated with synchronous swimming that may have contributed to increased adaptation and as a consequence may have influenced the evolution of schooling. The evolutionary development of the inner ear and the LLO increased the capacity to detect potential prey, possibly leading to an increased potential for cannibalism in the shoal, but also helped small fish to avoid joining larger fish, resulting in size homogeneity and, accordingly, an increased capacity for moving in synchrony. Water-movements and incidental sound produced as by-product of locomotion (ISOL may provide fish with potentially useful information during swimming, such as neighbour body-size, speed, and location. When many fish move close to one another ISOL will be energetic and complex. Quiet intervals will be few. Fish moving in synchrony will have the capacity to discontinue movements simultaneously, providing relatively quiet intervals to allow the reception of potentially critical environmental signals. Besides, synchronized movements may facilitate auditory grouping of ISOL. Turning preference bias, well-functioning sense organs, good health, and skillful motor performance might be important to achieving an appropriate distance to school neighbors and aid the individual fish in reducing time spent in the comparatively less safe school periphery. Turning preferences in ancestral fish shoals might have helped fish to maintain groups and stay in formation, reinforcing aforementioned predator confusion mechanisms, which possibly played a role in the lateralization of the vertebrate brain [Current Zoology 58 (1: 116–128, 2012].

  15. Feasibility of Documenting and Estimating Adult Fish Passage at Large Hydroelectric Facilities in the Snake River Using Video Technology; 1993 Final Report.

    Energy Technology Data Exchange (ETDEWEB)

    Hatch, Douglas R.; Pederson, David R.; Fryer, Jeffrey

    1994-07-01

    Lower Granite Dam on the Snake River to evaluate the feasibility of using video technology to document and estimate fish ladder passage of chinook salmon Oncorhynchus tshawytscha, sockeye salmon O. nerka, and steelhead O. mykiss. A video system was to produced video images during salmon passage periods. A technician identified and counted fish images from the video record. Fish ladder passage estimates of target species made from the video record were similar to estimates made by on-site counters during daytime periods, indicating that the two methods were relatively precise. We also found that a significant percentage (6.4% and 8.3%) of target salmonids migrated during nighttime periods when on-site counts were not typically made during the two years of study. Analysis of the video record permitted verification of individual sockeye salmon identified and counted by on-site count personnel, and provided data useful to managers of this ESA-listed stock. Analysis of the video record also permitted collection of additional data such as length measurements of individual specimens, which was used to regulate a fishery located upstream.

  16. Generation of non-classical correlated photon pairs via a ladder-type atomic configuration: theory and experiment

    CERN Document Server

    Ding, Dong-Sheng; Shi, Bao-Sen; Zou, Xu-Bo; Guo, Guang-Can

    2012-01-01

    We experimentally generate a non-classical correlated two-color photon pair at 780 and 1529.4 nm in a ladder-type configuration using a hot 85Rb atomic vapor with the production rate of ~107/s. The non-classical correlation between these two photons is demonstrated by strong violation of Cauchy-Schwarz inequality by the factor R=48+-12. Besides, we experimentally investigate the relations between the correlation and some important experimental parameters such as the single-photon detuning, the powers of pumps. We also make a theoretical analysis in detail and the theoretical predictions are in reasonable agreement with our experimental results.

  17. Magnetization plateaux and jumps in a class of frustrated ladders: A simple route to a complex behaviour

    OpenAIRE

    Honecker, A.; Mila, F.; Troyer, M.

    1999-01-01

    We study the occurrence of plateaux and jumps in the magnetization curves of a class of frustrated ladders for which the Hamiltonian can be written in terms of the total spin of a rung. We argue on the basis of exact diagonalization of finite clusters that the ground state energy as a function of magnetization can be obtained as the minimum - with Maxwell constructions if necessary - of the energies of a small set of spin chains with mixed spins. This allows us to predict wi...

  18. All Fish for China?

    OpenAIRE

    Villasante, Sebastián; Rodríguez-González, David; Antelo, Manel; Rivero-Rodríguez, Susana; José A. Santiago; Macho, Gonzalo

    2013-01-01

    In this paper we examine the effect of Gross Domestic Product (GDP) on the level of fish intake in China in comparison with the rest of the world. We also analyse the origin and destination of China’s seafood products in order to understand the main patterns during the last decades. The results show that in the 1961–2011 period the rate of growth of the GDP in China doubled that of other developing regions, while the daily fish intake of China increased fourfold, making China the largest fish...

  19. Ageing of Fish

    OpenAIRE

    Institute, Marine

    2006-01-01

    In order to assess the state of any fish stock it is vital that the age structure of that stock is known. The age profile of a stock gives an indication on how healthy the stock is. If there is a broad range of ages present, then the stock would appear to be in good shape. If there are no young fish, then recruitment (spawning) may have failed and there will be problems in the future. If there are no old fish in the stock, then there may be overfishing of the stock. Age data give a good insig...

  20. Amarillo fish (Girardinichthys multiradiatus) use visual landmarks to orient in space

    OpenAIRE

    Perera, TB; Garcia, CM

    2003-01-01

    Fish responsiveness to visual stimuli has been studied extensively in contexts such as female mate choice, predator inspection and schooling, yet surprisingly little work has been conducted on visual orientation in space in fish. Here we report on an experiment designed to test whether Amarillo fish can learn to find a goal within a maze more effectively in the presence of local visual landmarks than otherwise. We found that: (a) Amarillo fish can use landmarks to locate a goal, (b) there was...

  1. The Potency of Pineapple Waste to Increase the Quality of Tuna Fish Waste for Poultry Feedstuffs

    OpenAIRE

    S Suhermiyati; SJ Setyawati

    2008-01-01

    The objective of this research was to study the effect of bromelyn enzyme from pineapple waste on the quality of tuna fish waste. The information generated from this research used to increase the utilization of tuna fish waste for poultry feedstuff. This research was conducted experimentally using Completely Randomized Design (CRD) and Least Significant Difference (LSD). The treatments were P1 (head of tuna fish +12.5% bromelyn from pineapple steak); P2 (head of tuna fish +12.5% bromelyn fr...

  2. Transcriptomic Analysis of the Effects of a Fish Oil Enriched Diet on Murine Brains

    OpenAIRE

    Hammamieh, Rasha; Chakraborty, Nabarun; Gautam, Aarti; Miller, Stacy-Ann; Muhie, Seid; Meyerhoff, James; Jett, Marti

    2014-01-01

    The health benefits of fish oil enriched with high omega-3 polyunsaturated fatty acids (n-3 PUFA) are widely documented. Fish oil as dietary supplements, however, show moderate clinical efficacy, highlighting an immediate scope of systematic in vitro feedback. Our transcriptomic study was designed to investigate the genomic shift of murine brains fed on fish oil enriched diets. A customized fish oil enriched diet (FD) and standard lab diet (SD) were separately administered to two randomly cho...

  3. Fishing effects on energy use by North Sea fishes

    OpenAIRE

    Jennings, S.; van Hal, R.; Hiddink, J.G.; Maxwell, T.A.D.

    2008-01-01

    Fishing affects patterns of energy use in fish populations, as demonstrated by changes in population energy consumption and the size and age when energy demands are greatest. We compare theoretical predictions and observed patterns of energy use (expressed as the primary production required to support fish production) by North Sea fish, based on simple and widely applicable theory that links life history parameters, fishing mortality (F), trophic transfer efficiency and relationships between ...

  4. Response of potential fish community indicators to fishing

    OpenAIRE

    Piet, G. J.; Jennings, S.

    2005-01-01

    Fish community metrics and diversity indices have often been proposed as indicators to support an Ecosystem Approach to Fisheries Management. The response of eight fish community indicators to spatio-temporal changes in fishing effort was studied by comparing the rate of change in (i) areas subject to different levels (high, medium, and low) of fishing effort and (ii) areas inside and outside a closed area (the plaice box) where management measures led to changes in fishing effort over time. ...

  5. Estimating fishing mortality, natural mortality, and selectivity using recoveries from tagging young fish

    Science.gov (United States)

    Jiang, H.; Brownie, C.; Hightower, J.E.; Pollock, K.H.

    2007-01-01

    Current methods for estimation of age- and year-specific instantaneous mortality rates based on multiyear, multiple-age tagging studies assume that it is feasible to tag fish in a wide range of ages. For some species, however, only the youngest one or two age-classes are readily available for tagging. Given the practical advantages of tagging young fish only, an important question is whether such studies would provide the information needed for estimation of age-dependent mortality rates. We investigated three designs: tagging only the youngest available age-class, tagging the two youngest age-classes, and tagging the first five age-classes. We carried out simulation studies to assess estimator performance under these three designs, in each case assuming the same total number of tagged fish. Data were generated assuming fishing mortality rates to be age and year dependent and natural mortality rates to be constant or with limited age dependence. Estimator performance is best when fish are tagged in five age-classes, and tagging fish in the two youngest age-classes shows substantial improvement compared with tagging one age-class only. External information about the tag-reporting rate is necessary to obtain estimators with reasonable properties, especially in the case of models with age-dependent natural mortality. Such information can be obtained from auxiliary studies by means of high-reward tags or planted tags. Collecting recovery information for several additional years after the last release produces small improvements in precision and bias. If tagging fish in multiple age-classes is impractical, reasonable precision can be obtained by tagging one or preferably two age-classes and obtaining supplemental information on the reporting rate. For illustration, estimates of age-dependent fishing and natural mortality rates were obtained from tag returns on Chesapeake Bay striped bass Morone saxatilis tagged at ages 3 and 4 years. ?? Copyright by the American Fisheries Society 2007.

  6. Repertory grid, laddering e análise de conteúdo: uma abordagem psicométrica para entender profissionais de tecnologia da informação / Repertory grid, laddering, and content analysis: a psychometric approach to understand the information technology workforce

    Scientific Electronic Library Online (English)

    Pedro Jácome de, Moura Junior; Carlo Gabriel Porto, Bellini.

    2014-04-01

    Full Text Available Um dos principais desafios quando se lida com pessoas é delas obter informações confiáveis. A dificuldade advém do acesso àquilo que se encontra, literalmente, na mente das pessoas. As tentativas de acesso a esses conteúdos estão limitadas aos filtros cognitivos e à retórica da pessoa que está sendo [...] analisada. Neste artigo, repertory grid é aplicada com laddering e análise de conteúdo para confrontar construtos teóricos sobre gestão de equipes-cliente de tecnologia da informação (TI) com construtos “residentes” na cognição de profissionais de TI que implantam sistemas integrados de gestão (ERP). Os resultados demonstram a efetividade dessa composição metodológica para revelar fenômenos cognitivos e entender melhor os profissionais de TI. Abstract in english A major challenge when researching on people relates to how reliable information can be retrieved from them. It is a matter of how to access what is literally inside people’s mind. Access is limited by the cognitive screening process that mediates human interaction, as well as by human rhetoric. We [...] apply repertory grid, laddering and content analysis as an integrated psychometric approach to contrast two sets of constructs: a set of theoretically based constructs about the management of information technology professionals who work in customer teams, and a set of constructs that lie behind those professionals’ cognition in the particular case of implementing enterprise-wide systems (ERP). Results confirm the effectiveness of such a methodological approach to accurately reveal cognitive phenomena and to better understand the information technology workforce.

  7. 76 FR 28715 - Endangered and Threatened Species: Designation of a Nonessential Experimental Population for...

    Science.gov (United States)

    2011-05-18

    ...excess hatchery fish being used...survival and recovery for this DPS...experimental population will be designated...numbers of other fish from this...experimental population because enough fish will survive...not harm the recovery...

  8. 78 FR 2893 - Endangered and Threatened Species: Designation of a Nonessential Experimental Population for...

    Science.gov (United States)

    2013-01-15

    ...out in the Fish Passage Plan...of the NEP fish will not appreciably...survival and recovery for this DPS...experimental population will be designated...experimental population because enough fish will survive...not harm the recovery...

  9. Fish germ cells.

    Science.gov (United States)

    Xu, HongYan; Li, MingYou; Gui, JianFang; Hong, YunHan

    2010-04-01

    Fish, like many other animals, have two major cell lineages, namely the germline and soma. The germ-soma separation is one of the earliest events of embryonic development. Germ cells can be specifically labeled and isolated for culture and transplantation, providing tools for reproduction of endangered species in close relatives, such as surrogate production of trout in salmon. Haploid cell cultures, such as medaka haploid embryonic stem cells have recently been obtained, which are capable of mimicking sperm to produce fertile offspring, upon nuclear being directly transferred into normal eggs. Such fish originated from a mosaic oocyte that had a haploid meiotic nucleus and a transplanted haploid mitotic cell culture nucleus. The first semi-cloned fish is Holly. Here we review the current status and future directions of understanding and manipulating fish germ cells in basic research and reproductive technology. PMID:20596909

  10. West Coast Fishing Ethnography

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Created as part of a 2012 BOEM study on OCS renewable energy space-use conflicts, this data contains the commercial and recreational fishing locations off the...

  11. Automatic Fish Ageing (AFISA)

    OpenAIRE

    Mahe, Kelig; Parisi, Vincenc; Carbini, Sebastien; Soria, J.a.; Harbitz, A; De Pontual, Helene; Cotano, U; Songer, S; Millner, R.; Lewy, P; Gudmundsson, E.f; Fablet, Ronan; Benzinou, Abdesslam

    2009-01-01

    Most of the fish stocks are assessed using age-based models, however age estimations using otoliths costs several million euros annually. In this context, Automatic Fish Ageing (EU Project) would provide means to standardize ageing among laboratories and build interpreted image databases ensuring the information conservation. Automation improves growth studies while reducing the cost of the acquisition of age data. The whole processing chain from the acquisition of otolith data to the actu...

  12. Manual of Fish Sclerochronology

    OpenAIRE

    Panfili, Jacques; De Pontual, Helene; Troadec, Herve; Wrigh, Peter J.

    2002-01-01

    Sclerochronology, the study of calcified structures to reconstruct the past history of living organisms, is central to fish biology and fisheries management. This manual aims to provide an overview of the current theoretical and practical aspects of sclerochronological studies. By providing information on the nature of calcified structures (otoliths, scales, skeleton), their uses in fish research and methods for preparation and examination, the manual constitutes a comprehensive guide for res...

  13. Access and Fishing Activities

    DEFF Research Database (Denmark)

    Høst, Jeppe Engset

    2015-01-01

    In this chapter, I look at the implications of transferable quotas on the organization of production; that is, how fishing activities are structured around access to the individual and transferable quotas and how, in turn, the quotas structure the production. Therefore, this chapter will give a detailed ethnographic description of five different fishing operations and then compare them on a number of different fronts. This will direct us to some general differences in their modes of operation in...

  14. Fish Stem Cell Cultures

    OpenAIRE

    Ni Hong, Zhendong Li, Yunhan Hong

    2011-01-01

    Stem cells have the potential for self-renewal and differentiation. First stem cell cultures were derived 30 years ago from early developing mouse embryos. These are pluripotent embryonic stem (ES) cells. Efforts towards ES cell derivation have been attempted in other mammalian and non-mammalian species. Work with stem cell culture in fish started 20 years ago. Laboratory fish species, in particular zebrafish and medaka, have been the focus of research towards stem cell cultures. Medaka is th...

  15. Fe(x)Pb(4-x)Sb4Se10: a new class of ferromagnetic semiconductors with quasi 1D {Fe2Se10} ladders.

    Science.gov (United States)

    Poudeu, Pierre F P; Takas, Nathan; Anglin, Clarence; Eastwood, James; Rivera, Arianna

    2010-04-28

    A new family of quasi-one-dimensional ferromagnetic selenides with general formula Fe(x)Pb(4-x)Sb(4)Se(10) (0 B), was observed in Fe(0.75)Pb(3.25)Sb(4)Se(10) and FePb(3)Sb(4)Se(10) suggesting that the Fe(x)Pb(4-x)Sb(4)Se(10) (0 Goodenough-Kanamori rules suggested that the magnetism within the ladder and ladder-single chain systems in Fe(x)Pb(4-x)Sb(4)Se(10) phases is controlled by competing interactions. PMID:20369818

  16. Specific heat of an S=1/2 Heisenberg ladder compound Cu$_2$(C$_5$H$_{12}$N$_2$)$_2$Cl$_4$ under magnetic fields

    OpenAIRE

    Hagiwara, M.; Katori, H. A.; Schollwöck, U.; Mikeska, H. -J.

    1999-01-01

    Specific heat measurements down to 0.5 K have been performed on a single crystal sample of a spin-ladder like compound Cu$_{2}$(C$_{5}$H$_{12}$N$_{2}$)$_{2}$Cl$_{4}$ under magnetic fields up to 12 T. The temperature dependence of the observed data in a magnetic field below 6 T is well reproduced by numerical results calculated for the S=1/2 two-leg ladder with $J_{\\rm{rung}}$/$J_{\\rm{leg}}$=5. In the gapless region above 7 T ($H_{\\rm{c1}}$), the agreement between experiment ...

  17. Magnetic properties of the two-leg zig-zag ladder in quantum spin system NH4CuCl3

    International Nuclear Information System (INIS)

    Numerical analysis of the two-leg zig-zag ladder as a single chain with next-nearest neighbour interactions has been formulated by Cabra (1999) with the following Hamiltonian. Other formulation for two leg zig-zag ladder with dimerized chains and coupling between the chains. From these formulations, we study the closing of the gap at zero magnetization by means of the fine-tuning mechanism and disappearance of the 1/2 plateau (gap) at finite by alternating dimerization of the chains along the rungs. We also described NH4CuCI3 under high magnetic fields in a two-leg system

  18. Fish-robot interactions in a free-swimming environment: Effects of speed and configuration of robots on live fish

    Science.gov (United States)

    Butail, Sachit; Polverino, Giovanni; Phamduy, Paul; Del Sette, Fausto; Porfiri, Maurizio

    2014-03-01

    We explore fish-robot interactions in a comprehensive set of experiments designed to highlight the effects of speed and configuration of bioinspired robots on live zebrafish. The robot design and movement is inspired by salient features of attraction in zebrafish and includes enhanced coloration, aspect ratio of a fertile female, and carangiform/subcarangiformlocomotion. The robots are autonomously controlled to swim in circular trajectories in the presence of live fish. Our results indicate that robot configuration significantly affects both the fish distance to the robots and the time spent near them.

  19. Fish Culture Economics and Extension

    OpenAIRE

    E.N. Ogamba; J.F.N. Abowei

    2012-01-01

    Fish culture economics and extension was reviewed to enable fish culturist plan effectively before involved in fish culture and practices. The cost and benefits of fish culture need be known before participation in the business. There is need for cross-link between research and the fishing community. Prior to introduction of any new innovation in fisheries extension and evaluation of such programmers, the agency responsible for such exercise should have full knowledge of the existing farming ...

  20. Jurassic fishes of Gondwana

    Directory of Open Access Journals (Sweden)

    Adriana López-Arbarello

    2008-12-01

    Full Text Available The Jurassic is an important period for understanding the origin of modern fish faunas, since it saw the first radiation - and in some cases the origin - of most modern groups. In chondrichthyans, neoselachian sharks and rays diversified during this time. In actinopterygians, the neopterygians, and among them the teleosts, experienced an important radiation, which led to the appearance of several of the modern teleosts groups. In the sarcopterygians, dipnoans and actinistians approached their current forms. However, the Jurassic fossil record of fishes is strongly biased towards the Northern Hemisphere. The only notable Early Jurassic fish fauna from Gondwana is that of the Kota Formation of India. For the Middle Jurassic, the most important Gondwanan fish faunas are those of the Aalenian-Bathonian Stanleyville Beds of the Democratic Republic of Congo, in which a distinct freshwater and a marine fauna are found. In the Late Jurassic, the Gondwanan record is slightly better, with important marine faunas being known from the Oxfordian Quebrada del Profeta in Chile and the Tithonian Vaca Muerta Formation of Argentina. Freshwater faunas have been described from the Tithonian Talbragar Beds of eastern Australia and the Tithonian Cañadón Calcáreo Formation of Argentina. The taxonomic composition of the known marine actinopterygian faunas of Gondwana is in general agreement with faunas of the Northern Hemisphere. However, the Jurassic fish record from Gondwana is highly incomplete both stratigraphically and geographically, and most faunas are in need of revision, further hampering an interpretation of Jurassic fish evolution in the Southern Hemisphere.