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

Energy Technology Data Exchange (ETDEWEB)

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

Powers, Patrick D.; Orsborn, John F.

1985-08-01

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Selectivity of fish ladders: a bottleneck in Neotropical fish movement  

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

Carlos Sérgio Agostinho

2007-01-01

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Fish ladders: safe fish passage or hotspot for predation?  

Directory of Open Access Journals (Sweden)

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

Angelo Antonio Agostinho

2012-10-01

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

Energy Technology Data Exchange (ETDEWEB)

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

Orsborn, John F.

1985-08-01

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Fish ladders: safe fish passage or hotspot for predation?  

Scientific Electronic Library Online (English)

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

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

2012-10-01

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

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

Domingo Rodriguez Fernandez

2004-08-01

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

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

Luiz Gustavo Martins da Silva

2012-10-01

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

Energy Technology Data Exchange (ETDEWEB)

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

Aaserude, Robert G.; Orsborn, John F.

1985-08-01

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

Scientific Electronic Library Online (English)

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

Fernando Mayer, Pelicice; Carlos Sérgio, Agostinho.

2012-10-01

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Design a Fish  

Science.gov (United States)

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

Twin Cities Public Television, Inc.

2007-01-01

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

Scientific Electronic Library Online (English)

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

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

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Indirect effects of impoundment on migrating fish: temperature gradients in fish ladders slow dam passage by adult Chinook salmon and steelhead.  

Science.gov (United States)

Thermal layering in reservoirs upstream from hydroelectric dams can create temperature gradients in fishways used by upstream migrating adults. In the Snake River, Washington, federally-protected adult salmonids (Oncorhynchus spp.) often encounter relatively cool water in dam tailraces and lower ladder sections and warmer water in the upstream portions of ladders. Using radiotelemetry, we examined relationships between fish passage behavior and the temperature difference between the top and bottom of ladders (?T) at four dams over four years. Some spring Chinook salmon (O. tshawytscha) experienced ?T ? 0.5 °C. Many summer and fall Chinook salmon and summer steelhead (O. mykiss) experienced ?T ? 1.0 °C, and some individuals encountered ?T > 4.0°C. As ?T increased, migrants were consistently more likely to move down fish ladders and exit into dam tailraces, resulting in upstream passage delays that ranged from hours to days. Fish body temperatures equilibrated to ladder temperatures and often exceeded 20°C, indicating potential negative physiological and fitness effects. Collectively, the results suggest that gradients in fishway water temperatures present a migration obstacle to many anadromous migrants. Unfavorable temperature gradients may be common at reservoir-fed fish passage facilities, especially those with seasonal thermal layering or stratification. Understanding and managing thermal heterogeneity at such sites may be important for ensuring efficient upstream passage and minimizing stress for migratory, temperature-sensitive species. PMID:24392020

Caudill, Christopher C; Keefer, Matthew L; Clabough, Tami S; Naughton, George P; Burke, Brian J; Peery, Christopher A

2013-01-01

13

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

Directory of Open Access Journals (Sweden)

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

Domingo Rodriguez Fernandez

2007-01-01

14

Evaluation of fish passage through the Igarapé Dam fish ladder (rio Paraopeba, Brazil), using marking and recapture  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Desde 1978, o rio Paraopeba, um afluente do rio São Francisco, tem uma barragem de 6 metros de altura para desvio de água para a Usina Térmica de Igarapé. Em 1994, uma escada para peixes foi construída nessa barragem. Os resultados de um programa de marcação e recaptura realizado entre 1997 e 2001 s [...] ão descritos, utilizando dados prévios de estudos das comunidades de peixes conduzidos em dez estações de amostragem entre 1994 e 1997. Estes estudos demonstraram a presença de pelo menos 91 espécies no rio Paraopeba. Durante quatro estações chuvosas entre 1997 e 2000, peixes foram capturados abaixo da barragem, marcados com marcas externas, e imediatamente soltos no mesmo ponto. O objetivo desse trabalho foi avaliar a passagem pela escada, com base nas recapturas informadas por pescadores artesanais e esportivos. No total foram marcados 3.642 indivíduos, atingindo aproximadamente 1,33 tonelada em biomassa. Vinte e seis espécies foram utilizadas, representando 28.5% da riqueza total registrada (91 espécies). O tempo máximo verificado de retenção da marca foi de 10 meses. A taxa de retorno total foi de 4,37% em quatro anos, atingindo 5,75% no último período (2000-2001). Do total recapturado, 14% ocorreram a montante da escada. As espécies recapturadas a montante foram o piau-verdadeiro (Leporinus obtusidens), mandi-amarelo (Pimelodus maculatus) e curimatá-pioa (Prochilodus costatus). Essas espécies apresentaram área de vida de 15,4, 81,5 e 232,0 km, respectivamente. O maior número de recapturas ocorreu imediatamente a jusante da barragem da UTE Igarapé, um dos locais de pesca mais intensa em todo o rio. Abstract in english Rio Paraopeba, a tributary of rio São Francisco, has a six-meter high dam, built in 1978 to divert water to the Igarapé Thermal Power Plant. In 1994, a fish ladder was built at this dam. The results of a marking and recapture program carried out along rio Paraopeba between 1997 and 2001 are describe [...] d, using information from fish community studies conducted at ten sampling stations between 1994 and 1997. These investigations showed the presence of at least 91 species in the river. During four rainy seasons between 1997 and 2000, fish were caught downstream of the dam, marked with external plastic tags, and immediately released at the same site. The objective was to evaluate fish passage through the ladder, based on recapture information from artisanal and sport fishermen. A total of 3,642 specimens were marked, adding up to a biomass of approximately 1.33 tons. Twenty-six species were used, representing 28.5% of the total recorded richness (91 species). Maximum recorded tag retention time was 10 months. Total recapture rate was 4.37% in four years, reaching 5.75% in the last period (2000-2001). Of all recaptured specimens, 14.0% were caught upstream of the dam, evidencing passage through the ladder. The specimens recaptured upstream of the dam belonged to three species: piau-verdadeiro (Leporinus obtusidens), mandi-amarelo (Pimelodus maculatus) and curimatá-pioa (Prochilodus costatus). These species showed linear home ranges of 15.4, 81.5 and 232.0 km, respectively. Most recaptures occurred immediately downstream of the dam, one of the most intensely fished stretches of rio Paraopeba.

Carlos Bernardo Mascarenhas, Alves.

15

Computer Aided Design Of Relay Ladder Logic Via State Transition Diagram  

Science.gov (United States)

Programmable logic controllers (PLCs) are commonly programmed using relay ladder logic. There are many disadvantages to this approach. The state transition diagram affords a systematic means of providing precise and unambiguous specification while at the same time yielding a good system overview for ease of troubleshooting and maintenance. Computer aided logic design techniques help to automate the process of relay logic design for the state transition diagram. A software package which runs on an IBM PC/compatible machine has been developed to automatically transform the state diagram specification into relay ladder logic and the associated (PLC dependent) source code.

Devanathan, R.; Kuan, Foo Y.; Jun, Chang C.; Aun, Choo S.

1987-10-01

16

Correspondence - Design of ladder-type SAW/BAW.  

Science.gov (United States)

This paper describes the design of RF SAW/ BAW filters with constant group delay. The band-pass LC filter is designed based on the traditional Bessel filter design. Then, LC resonators in the filter are replaced by SAW/BAW resonators with finite capacitance ratio ?. Finite ? generates passband ripples in the group delay. However, it is shown the ripples can be suppressed by optimal design of the SAW/BAW resonators. Norton's first transform is also applied to the designed filter to reduce variation of resonator shunt capacitances. Finally, extremely flat group delay with deviation of 4 ns over the frequency range of ±20 MHz at the center frequency of 1 GHz is theoretically demonstrated. PMID:23221231

Wang, Hualei; Chen, Jing; Shi, Yu; Omori, Tatsuya; Ahn, Changjun; Hashimoto, Ken-ya

2012-12-01

17

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

Directory of Open Access Journals (Sweden)

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

Domingo Rodrigues Fernandez

2007-01-01

18

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

OpenAIRE

An approach to design and implement the control function of LD (Ladder Diagram) in the hydropower simulation system based on all paths searching algorithm is proposed in this paper. LD is widely used as a programming language for PLC (Programmable Logic Controller), but it doesn’t be executed automatically in the hydropower simulation system which is a software system, and there is no compiler or interpretation for LD in it. The approach in this paper is not only to present a graphical inte...

Song, Chun-he; Zhao, Hai; Li, Hui; Ai, Jun; Li, Bo

2009-01-01

19

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

Scientific Electronic Library Online (English)

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

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

20

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

Science.gov (United States)

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

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

2009-07-01

21

Ladder Logic  

Science.gov (United States)

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

Kuphaldt, Tony R.

22

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

International Nuclear Information System (INIS)

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

23

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

Scientific Electronic Library Online (English)

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

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

24

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

Directory of Open Access Journals (Sweden)

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

Chun-He SONG

2009-07-01

25

A High Efficiency, Miniaturized Ka Band Traveling Wave Tube Based on a Novel Finned Ladder RF Circuit Design  

Science.gov (United States)

Space communications architectures are being planned to meet the high rate data distribution requirements of future NASA Enterprise missions. These will require the use of traveling wave tube amplifiers (TWTAs) to provide the high frequency, RF (radio frequency) power and efficiency needed for many of the communications links. A program addressing these requirements is currently underway at NASA Glenn Research Center (GRC) for the development of a high efficiency, 20 watt, 32 GHz TWT of reduced size and weight that is based on a novel high gain n circuit design, termed the 'finned ladder'.

Wintucky, E. G.; Wilson, J. D.; Vaden, K. R.; Force, D. A.; Freeman, J. C.; Lesny, G. G.; Kory, C. L.; Chevalier, C. T.; Ebihara, B.; Dayton, J. A.; Williams, W. D. (Technical Monitor)

2001-01-01

26

Voegelin's Ladder  

Directory of Open Access Journals (Sweden)

Full Text Available Leadership has non-logical aspects. One of these is spirituality. Voegelin’s Ladder provides a context for studying spirituality as a part of leadership. What it reveals is that spirituality arises at the intersection of the human with the divine. Spirituality expresses itself as purpose and aspiration, which a leader embodies.

Nathan Harter

2006-06-01

27

Design concepts for a high-impedance narrow-band 42 GHz power TWT using a fundamental/forward ladder-based circuit  

Science.gov (United States)

A low-cost, narrowband, millimeter wave space communications TWT design was studied. Cold test interaction structure scale models were investigated and analyses were undertaken to predict the electrical and thermal response of the hypothetical 200 W TWT at 42 GHz and 21 kV beam voltage. An intentionally narrow instantaneous bandwidth (1%, with the possibility of electronic tuning of the center frequency over several percent) was sought with a highly dispersive, high impedance "forward wave' interaction structure based on a ladder (for economy in fabrication) and nonspace harmonic interaction, for a high gain rate and a short, economically focused tube. The "TunneLadder' interaction structure devised combines ladder properties with accommodation for a pencil beam. Except for the impedance and bandwidth, there is much in common with the millimeter wave helix TWTs which provided the ideal of diamond support rods. The benefits of these are enhanced in the TunneLadder case because of spatial separation of beam interception and RF current heating.

Karp, A.

1980-01-01

28

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

International Nuclear Information System (INIS)

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

29

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

Scientific Electronic Library Online (English)

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

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

2012-10-01

30

Fish Protection: Cooperative research advances fish-friendly turbine design  

Energy Technology Data Exchange (ETDEWEB)

Renewable hydropower is a tremendous resource within the Pacific Northwest that is managed with considerable cost and consideration for the safe migration of salmon. Recent research conducted in this region has provided results that could lower the impacts of hydro power production and make the technology more fish-friendly. This research is now being applied during a period when a huge emphasis is being made to develop clean, renewable energy sources.

Brown, Richard S.; Ahmann, Martin L.; Trumbo, Bradly A.; Foust, Jason

2012-12-01

31

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-07-01

32

Ladder/PLC's  

Science.gov (United States)

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

33

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

CERN Document Server

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 for a two-term fractional differential equation. The experiment showed that in the frequency domain the domino ladder behaves as a system of order 0.5 and the nested ladder as a system of order 0.25, which is in perfect agreement with the theory developed for their design. In the time domain, however, the order of the domino ladder is changing from roughly 0.5 to almost 1, and the order of the nested ladder is changing in a similar manner, from roughly 0.25 to almost 1; in both cases, the order 1 is never reached, and both systems remain th...

Sierociuk, Dominik; Petras, Ivo

2011-01-01

34

Novel high-gain, improved-bandwidth, finned-ladder V-band Traveling-Wave Tube slow-wave circuit design  

Science.gov (United States)

The V-band frequency range of 59-64 GHz is a region of the millimeter-wave spectrum that has been designated for inter-satellite communications. As a first effort to develop a high-efficiency V-band Traveling-Wave Tube (TWT), variations on a ring-plane slow-wave circuit were computationally investigated to develop an alternative to the more conventional ferruled coupled-cavity circuit. The ring-plane circuit was chosen because of its high interaction impedance, large beam aperture, and excellent thermal dissipation properties. Despite these advantages, however, low bandwidth and high voltage requirements have, until now, prevented its acceptance outside the laboratory. In this paper, the three-dimensional electrodynamic simulation code MAFIA (solution of MAxwell's Equation by the Finite-Integration-Algorithm) is used to investigate methods of increasing the bandwidth and lowering the operating voltage of the ring-plane circuit. Calculations of frequency-phase dispersion, beam on-axis interaction impedance, attenuation and small-signal gain per wavelength were performed for various geometric variations and loading distributions of the ring-plane TWT slow-wave circuit. Based on the results of the variations, a circuit termed the finned-ladder TWT slow-wave circuit was designed and is compared here to the scaled prototype ring-plane and a conventional ferruled coupled-cavity TWT circuit over the V-band frequency range. The simulation results indicate that this circuit has a much higher gain, significantly wider bandwidth, and a much lower voltage requirement than the scaled ring-plane prototype circuit, while retaining its excellent thermal dissipation properties. The finned-ladder circuit has a much larger small-signal gain per wavelength than the ferruled coupled-cavity circuit, but with a moderate sacrifice in bandwidth.

Kory, Carol L.; Wilson, Jeffrey D.

1994-01-01

35

Hole doped Hubbard ladders  

CERN Document Server

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.

Fehske, H; Wellein, G; Jeckelmann, E

2006-01-01

36

Integrable Stochastic Ladder Models  

CERN Document Server

A general way to construct ladder models with certain Lie algebraic or quantum Lie algebraic symmetries is presented. These symmetric models give rise to series of integrable systems. It is shown that corresponding to these SU(2) symmetric integrable ladder models there are exactly solvable stationary discrete-time (resp. continuous-time) Markov processes with transition matrices (resp. intensity matrices) having spectra which coincide with the ones of the corresponding integrable models.

Albeverio, Sergio A; Albeverio, Sergio; Fei, Shao-Ming

2001-01-01

37

Bioinspiration from fish for smart material design and function  

International Nuclear Information System (INIS)

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

38

Bioinspiration from fish for smart material design and function  

Science.gov (United States)

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.

Lauder, G. V.; Madden, P. G. A.; Tangorra, J. L.; Anderson, E.; Baker, T. V.

2011-09-01

39

Improved intake design for downstream migrating fish at hydropower plants  

International Nuclear Information System (INIS)

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

40

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

Directory of Open Access Journals (Sweden)

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

Marshall C. Richmond

2007-11-01

41

Fish swarm optimization algorithm applied to engineering system design  

Scientific Electronic Library Online (English)

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

Fran Sérgio, Lobato; Valder, Steffen Jr..

2014-01-01

42

Design and construction of Eicher penstock fish screens  

International Nuclear Information System (INIS)

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

43

Particle-hole ladders  

OpenAIRE

A self contained analysis demonstrates that the sum of all particle-hole ladder contributions for a two dimensional, weakly coupled fermion gas with a strictly convex Fermi curve at temperature zero is bounded. This is used in our construction of two dimensional Fermi liquids.

Feldman, Joel S.; Kno?rrer, Horst; Trubowitz, Eugene; Forschungsinstitut für Mathematik (Zürich)

2001-01-01

44

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

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

2010-07-01

45

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

Science.gov (United States)

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

Liu, Yang; Xu, Jin; Lai, Jian-Qiang; Xu, Xiong; Shen, Fei; Wei, Yan-Yu; Huang, Min-Zhi; Tang, Tao; Gong, Yu-Bin

2012-07-01

46

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

International Nuclear Information System (INIS)

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

47

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.

48

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

Science.gov (United States)

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

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

2011-12-01

49

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

OpenAIRE

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

Favaro, Brett

2013-01-01

50

Trion ladder diagrams  

CERN Document Server

We first derive a new ``commutation technique'' for an exciton interacting with electrons, inspired from the one we recently developed for excitons interacting with excitons. These techniques allow to take \\emph{exactly} into account the possible exchanges between carriers. We use it to get the $\\mathrm{X}^-$ trion creation operator in terms of exciton and free-electron creation operators. In a last part we generate the ladder diagrams associated to these trions. Although similar to the exciton ladder diagrams, with the hole replaced by an exciton, they are actually much more tricky : (i) Due to the composite nature of the exciton, one cannot identify an exciton-electron potential similar to the Coulomb potential between electron and hole ; (ii) the spins are unimportant for excitons while they are crucial for trions, singlet and triplet states having different energies.

Combescot, M

2002-01-01

51

FPGA Implementations of Ladder Diagrams  

Directory of Open Access Journals (Sweden)

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

Neil William Bergmann

2013-02-01

52

Fish  

Science.gov (United States)

... Transplant Patients Infants and Young Children Publications & Materials Fish Share Compartir Fish, frogs, toads, and the water they live in ... more likely than others to get diseases from fish and amphibians. A person's age and health status ...

53

Wannier-Stark ladders in one-dimensional elastic systems  

CERN Document Server

The optical analogues of Bloch oscillations and their associated Wannier-Stark ladders have been recently analyzed. In this paper we propose an elastic realization of these ladders, employing for this purpose the torsional vibrations of specially designed one-dimensional elastic systems. We have measured, for the first time, the ladder wave amplitudes, which are not directly accessible either in the quantum mechanical or optical cases. The wave amplitudes are spatially localized and coincide rather well with theoretically predicted amplitudes. The rods we analyze can be used to localize different frequencies in different parts of the elastic systems and viceversa.

Gutíerrez, L; Flores, J; Méndez-Sánchez, R A; Monsivais, G; Morales, A

2006-01-01

54

Theon's Ladder for Any Root  

Science.gov (United States)

Theon's ladder is an ancient algorithm for calculating rational approximations for the square root of 2. It features two columns of integers (called a ladder), in which the ratio of the two numbers in each row is an approximation to the square root of 2. It is remarkable for its simplicity. This algorithm can easily be generalized to find rational…

Osler, Thomas J.; Wright, Marcus; Orchard, Michael

2005-01-01

55

Effective actions for spin ladders  

CERN Document Server

We derive a path-integral expression for the effective action in the continuum limit of an AFM Heisenberg spin ladder with an arbitrary number of legs. The map is onto an O(3) nonlinear-sigma-model with the addition of a topological term that is effective only for odd-legged ladders and half-odd integer spins. We derive the parameters of the effective nonlinear-sigma-model and the behaviour of the spin gap for the case of even-legged ladders.

Dell'Aringa, S; Morandi, G; Pieri, P; Roncaglia, M

1996-01-01

56

Integral representations combining ladders and crossed-ladders  

Science.gov (United States)

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

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

2014-07-01

57

Integral representations combining ladders and crossed-ladders  

CERN Document Server

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

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

2014-01-01

58

Fish-Friendly Engineering  

Science.gov (United States)

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

Integrated Teaching And Learning Program

59

Impact of Small Hydro-Power Plants on Salmonid Fishes Spawning Migrations  

OpenAIRE

In 2000 and 2005, fish ladders were built in Vilnia and Siesartis rivers providing fish access to another 10 and 25 km of the rivers respectively. The analysis of redd distribution and abundance in both rivers revealed that the construction of fish ladders significantly increased the number and share of redds above dams, however, a significant increase in redds above the dam occurred 2-4 years after fish ladders construction supporting homing behaviour as one of the most important factors ...

Saulius Stak?nas; K?stutis Skrupskelis

2011-01-01

60

A Review and Modern Approach to LC Ladder Synthesis  

Directory of Open Access Journals (Sweden)

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

Alexander J. Casson

2011-01-01

61

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

OpenAIRE

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...

Mohsen Siahmansouri; Ahmad Ghanbari; Mir Masoud Seyyed Fakhrabadi

2011-01-01

62

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...the use of ladder safety devices. Each step or...spreader or locking device shall be provided...covering, except for identification or warning labels...that a deflection device is installed to...wells, ladder safety devices, or...

2010-07-01

63

Variations of the Sliding Ladder Problem  

Science.gov (United States)

This article takes another look at the sliding ladder problem that students meet in the study of related rates in calculus. Physically realistic situations with both constrained and understrained ladders are explored.

Kapranidis, Stelios; Koo, Reginald

2008-01-01

64

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

OpenAIRE

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...

Santoshkumar; Vishal Hiremath

2012-01-01

65

Rank numbers for bent ladders  

Directory of Open Access Journals (Sweden)

Full Text Available A ranking on a graph is an assignment of positive integers to its vertices such that any path between two vertices with the same label contains a vertex with a larger label. The rank number of a graph is the fewest number of labels that can be used in a ranking. The rank number of a graph is known for many families, including the ladder graph P2 × Pn. We consider how ”bending” a ladder affects the rank number. We prove that in certain cases the rank number does not change, and in others the rank number differs by only 1. We investigate the rank number of a ladder with an arbitrary number of bends

Richter Peter

2014-05-01

66

Transformations of triangle ladder diagrams  

OpenAIRE

It is shown how dual space diagrammatic representation of momentum integrals corresponding to triangle ladder diagrams with an arbitrary number of rungs can be transformed to half-diamonds. In paper arXiv:0803.3420 [hep-th] the half-diamonds were related by conformal integral substitution to the diamonds which represent the dual space image of four-point ladder integrals in the four-dimensional momentum space. Acting in the way described in the present paper we do not need t...

Kondrashuk, Igor; Vergara, Alvaro

2009-01-01

67

Getting Clever with the Sliding Ladder  

Science.gov (United States)

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

De, Subhranil

2014-01-01

68

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

69

Six-Degree-of-Freedom Sensor Fish Design: Governing Equations and Motion Modeling  

Energy Technology Data Exchange (ETDEWEB)

The Sensor Fish device is being used at Northwest hydropower projects to better understand the conditions fish experience during passage through hydroturbines and other dam bypass alternatives. Since its initial development in 1997, the Sensor Fish has undergone numerous design changes to improve its function and extend the range of its use. The most recent Sensor Fish design, the three degree of freedom (3DOF) device, has been used successfully to characterize the environment fish experience when passing through turbines, in spill, or in engineered fish bypass facilities at dams. Pacific Northwest National Laboratory (PNNL) is in the process of redesigning the current 3DOF Sensor Fish device package to improve its field performance. Rate gyros will be added to the new six degree of freedom (6DOF) device so that it will be possible to observe the six linear and angular accelerations of the Sensor Fish as it passes the dam. Before the 6DOF Sensor Fish device can be developed and deployed, governing equations of motion must be developed in order to understand the design implications of instrument selection and placement within the body of the device. In this report, we describe a fairly general formulation for the coordinate systems, equations of motion, force and moment relationships necessary to simulate the 6DOF movement of an underwater body. Some simplifications are made by considering the Sensor Fish device to be a rigid, axisymmetric body. The equations of motion are written in the body-fixed frame of reference. Transformations between the body-fixed and interial reference frames are performed using a formulation based on quaternions. Force and moment relationships specific to the Sensor Fish body are currently not available. However, examples of the trajectory simulations using the 6DOF equations are presented using existing low and high-Reynolds number force and moment correlations. Animation files for the test cases are provided in an attached CD. The next phase of the work will focus on the refinement and application of the 6DOF simulator developed in this project. Experimental and computational studies are planned to develop a set of force and moment relationships that are specific to the Sensor Fish body over the range of Reynolds numbers that it experiences. Lab testing of prototype 6DOF Sensor Fish will also allow for refinement of the trajectory simulations through comparison with observations in test flumes. The 6DOF simulator will also be an essential component in tools to analyze field data measured using the next generation Sensor Fish. The 6DOF simulator will be embedded in a moving-machinery computational fluid dynamics (CFD) model for hydroturbines to numerically simulate the 6DOF Sensor Fish.

Deng, Zhiqun; Richmond, Marshall C.; Simmons, Carver S.; Carlson, Thomas J.

2004-08-19

70

Ladder-Type Circuits Revisited  

Science.gov (United States)

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…

Yoon, Sung Hyun

2007-01-01

71

Hydraulic design of a tilting weir allowing for periodic fish migration  

OpenAIRE

The hydraulic design of a tilting weir is presented, which allows for periodic exchange of potadromous fish between freshwater ecosystems. The application domain includes inland waters that need to be isolated hydraulically, preserving the existing ecological connection with the surrounding areas as much as possible. In the absence of a hydraulic gradient, the weir is opened in its neutral position and fish can bypass through passages sideways of the weir. When a hydraulic gradient develops i...

Hoitink, A. J. F.; Dommerholt, A.; Gerven, L. P. A.

2008-01-01

72

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

Science.gov (United States)

...importation of live fish, fertilized eggs, and gametes. 93.902 Section 93.902 Animals...importation of live fish, fertilized eggs, and gametes. (a) The following ports are designated...for live fish, fertilized eggs, and gametes of SVC-susceptible species...

2010-01-01

73

A New Polyether Ladder Compound Produced by the Dinoflagellate Karenia brevis  

OpenAIRE

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...

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

2005-01-01

74

A new polyether ladder compound produced by the dinoflagellate Karenia brevis.  

Science.gov (United States)

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 acetal derivative, are described in this paper. PMID:15679307

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

2005-01-01

75

Magnetization Properties of Some Quantum Spin Ladders  

OpenAIRE

The experimental realization of various spin ladder systems has prompted their detailed theoretical investigations. Here we study the evolution of ground state magnetization with an external magnetic field for two different antiferromagnetic systems: a three-legged spin-1/2 ladder, and a two-legged spin-1/2 ladder with an additional diagonal interaction. The finite system density-matrix renormalization group method is employed for numerical studies of the three-chain system,...

Tandon, Kunj; Lal, Siddhartha; Pati, Swapan K.; Ramasesha, S.; Sen, Diptiman

1998-01-01

76

Quantum Criticality in Dimerized Spin Ladders  

OpenAIRE

We analyze a possibility of quantum criticality (gaplessness) in dimerized antiferromagnetic two- and three-leg spin-1/2 ladders. Contrary to earlier studies of these models, we examine different dimerization patterns in the ladder. We find that ladders with the columnar dimerization order have lower zero-temperature energies and they are always gapped. For the staggered dimerization order, we find the quantum critical lines, in agreement with earlier analyses. The bond mean...

Chitov, Gennady Y.; Ramakko, Brandon W.; Azzouz, Mohamed

2007-01-01

77

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

Directory of Open Access Journals (Sweden)

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

Santoshkumar

2012-05-01

78

5 CFR 335.104 - Eligibility for career ladder promotion.  

Science.gov (United States)

... § 335.104 Eligibility for career ladder promotion. No employee shall receive a career ladder promotion unless his or her current rating of record under part...addition, no employee may receive a career ladder promotion who has a...

2010-01-01

79

Make a Human Scale Ladder  

Science.gov (United States)

In this quick activity about size and scale (on page 2 of the PDF), each learner will be given an image of an object and communicate with other members of the group to arrange the objects they are holding in order of size (largest objects on one end and smallest on the other). Scale ladders help kids recognize the order of magnitude of some benchmark objects and correctly arrange them in order of size. This exercise also increases familiarity with the metric system, the universal language used by scientists, and some common prefixes such as "micro" and "nano." Also relates to linked video, DragonflyTV Nano: What's Nano?

Twin Cities Public Television, Inc.

2008-01-01

80

Acoustic Wannier-Stark ladders and Bloch oscillations in porous silicon structures  

Science.gov (United States)

We report the experimental observation of the Wannier-Stark ladders and the Bloch oscillations for acoustic waves in porous silicon structures. We designed and fabricated a structure with an acoustic band gap centered around 1 GHz. We introduced a linear gradient in the acoustical parameter ?=1 /vL2 to obtain an acoustical Wannier-Stark ladder and we observed it from the transmission measurements. The observed behavior is in excellent agreement with transfer matrix calculations.

Lazcano, Z.; Arriaga, J.

2014-12-01

81

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...as measured between center lines of the rungs, cleats, and...toeboards for falling object and overhead protection on platforms and...clearance between the center line of fixed ladder rungs, cleats...employee or the ladder could contact exposed energized...

2010-07-01

82

Perspective on rainbow-ladder truncation  

CERN Document Server

Prima facie the systematic implementation of corrections to the rainbow-ladder truncation of QCD's Dyson-Schwinger equations will uniformly reduce in magnitude those calculated mass-dimensioned results for pseudoscalar and vector meson properties that are not tightly constrained by symmetries. The aim and interpretation of studies employing rainbow-ladder truncation are reconsidered in this light.

Eichmann, G; Cloet, I C; Krassnigg, A; Roberts, C D

2008-01-01

83

29 CFR 1926.1053 - Ladders.  

Science.gov (United States)

...each extra-heavy-duty type 1A metal or plastic ladder shall sustain at least 3...extra-heavy-duty type 1A metal or plastic ladders shall sustain at least 3...including, but not limited to, flat metal or concrete surfaces that are constructed so...

2010-07-01

84

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...so treated as to have no deleterious effect one upon the other. EC27OC91.002 Figure D-2—Rail Ladder With Bar Steel Rails and Round Steel Rungs (c) Clearance —(1) Climbing side. On fixed ladders, the perpendicular...

2010-07-01

85

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

Directory of Open Access Journals (Sweden)

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.

Mohsen Siahmansouri

2011-11-01

86

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

OpenAIRE

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

Drew, Joshua A.; Barber, Paul H.

2012-01-01

87

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

Directory of Open Access Journals (Sweden)

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

Wang R.W.

2010-02-01

88

Phase separation in t-J ladders  

OpenAIRE

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

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

1999-01-01

89

Impact of Small Hydro-Power Plants on Salmonid Fishes Spawning Migrations  

Directory of Open Access Journals (Sweden)

Full Text Available In 2000 and 2005, fish ladders were built in Vilnia and Siesartis rivers providing fish access to another 10 and 25 km of the rivers respectively. The analysis of redd distribution and abundance in both rivers revealed that the construction of fish ladders significantly increased the number and share of redds above dams, however, a significant increase in redds above the dam occurred 2-4 years after fish ladders construction supporting homing behaviour as one of the most important factors for the recolonization of the newly accessible habitats. The tracking of radio tagged salmon and sea trout revealed that statistically, significantly more time, fishes spent in the middle part of fish ladders. Assessed fish ladders efficiency for migrating salmonids made 66%. Minor construction defects and lack of protection were the main factors reducing fishway efficiency. Based on radio tracking data, recommendations are given for minor changes in fish ladders construction and operating schedule to increase the efficiency of fish ladders.Article in English

Saulius Stak?nas

2011-04-01

90

29 CFR 1917.118 - Fixed ladders.  

Science.gov (United States)

...or sliding attachments. (4) Well means a permanent complete enclosure around a fixed ladder, which...4) The minimum distance between the rung center line and the nearest permanent object behind the rung shall be 4 inches...

2010-07-01

91

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-02-01

92

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

OpenAIRE

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 wideb...

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

2006-01-01

93

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

OpenAIRE

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

Marcia Regina Simões; Reinaldo Aparecido Bariccatti; Caio Guilherme Secco Souza; José Dilson Silva de Oliveira

2011-01-01

94

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

Directory of Open Access Journals (Sweden)

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

Marcia Regina Simões

2011-06-01

95

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

Science.gov (United States)

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

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

2014-11-01

96

Determination of basic elements and features of medium fishing trawlers on initial stages of designing  

Directory of Open Access Journals (Sweden)

Full Text Available Over hundred of projects of medium fishing vessels, designed in Russia (including USSR, Europe, Japan and Vietnam have been examined. The analysis of their basic design characteristics is made. The purpose of the investigation is to define general principles of changes in width B, board height H, freight draft T, greater displacement and load-carrying capacity according to effective vessel length L^^. The effective dependences which allow to define the greatest width, board height, freight draft, relative values (L^^/B, ?/?, ?/?, full displacement and load-carrying capacity of a vessel depending on its effective length.

Lyong Hung Ngoc

2009-04-01

97

Magnetic Susceptibilities of Spin-1/2 Antiferromagnetic Heisenberg Ladders and Applications to Ladder Oxide Compounds  

CERN Document Server

A comprehensive theoretical and experimental study is presented of the magnetic susceptibility versus temperature \\chi(T) of spin S = 1/2 two- and three-leg Heisenberg ladders and ladder oxide compounds. Extensive quantum Monte Carlo simulations of \\chi(T) were carried out for both isolated and coupled two-leg ladders with spatially anisotropic intraladder exchange. Accurate fits to these and related literature QMC data were obtained. We have also calculated the one- and two-magnon dispersion relations and the dynamical spin structure factor for anisotropic isolated 2 x 12 ladders. The exchange constants in the two-leg ladder compound SrCu2O3 are estimated from LDA+U calculations. We report the detailed crystal structure of SrCu2O3 and of the three-leg ladder compound Sr2Cu3O5. New experimental \\chi(T) data are reported for the two-leg ladder cuprates SrCu2O3 and LaCuO_{2.5}, and for the (nominally) two-leg ladder vanadates CaV2O5 and MgV2O5. The new and literature spins-1/2 are thereby estimated for each mat...

Johnston, D C; Miyahara, S; Lidsky, D; Ueda, K; Azuma, M; Hiroi, Z; Takano, M; Isobe, M; Ueda, Y; Korotin, M A; Anisimov, V I; Mahajan, A V; Miller, L L

2000-01-01

98

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.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 comercialmente 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.

Jonathan K. Wells

2006-06-01

99

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

100

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)

101

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

Science.gov (United States)

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

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

2014-01-01

102

29 CFR 1910.25 - Portable wood ladders.  

Science.gov (United States)

...vii) [Reserved] (viii) Ladders with broken or missing steps, rungs, or cleats, broken side rails, or other faulty equipment shall...xvii) Middle and top sections of sectional or window cleaner's ladders should not be used...

2010-07-01

103

29 CFR Appendix A to Subpart X of... - Ladders  

Science.gov (United States)

...American National Standards Institute (ANSI) A14.1-1982—American National Standard...Manufactured portable metal ladders: ANSI A14.2-1982—American National Standard...Requirements. • Manufactured fixed ladders: ANSI A14.3-1984—American National...

2010-07-01

104

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

Science.gov (United States)

...Stairtowers, stairways, ladders, and elevators. 116.438 Section 116.438 Shipping COAST GUARD, DEPARTMENT OF HOMELAND... CONSTRUCTION AND ARRANGEMENT Fire Protection § 116.438 Stairtowers, stairways, ladders, and...

2010-10-01

105

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

Directory of Open Access Journals (Sweden)

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

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

2010-10-01

106

Failure Analysis of an Aluminum Extension Portable Ladder  

OpenAIRE

The conditions of end supports of straight ladders are often the cause of major injuries. The firm and secure ladder ends against instability in general and sliding of the top and bottom ends in particular are among the check list of most ladder safety training books and manuals. However, the restraint to the free expansion of a ladder can cause a catastrophic failure due to buckling even at intermediate ...

Abdel-Hakim Bouzid

2014-01-01

107

The Static Ladder Problem with Two Sources of Friction  

Science.gov (United States)

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…

Bennett, Jonathan; Mauney, Alex

2011-01-01

108

29 CFR 1910.25 - Portable wood ladders.  

Science.gov (United States)

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

2010-07-01

109

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

OpenAIRE

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). ...

Zhang, Bing; A?lvarez Casado, Enrique; Tello Sandoval, Sonija; Mondelo, Pedro

2010-01-01

110

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

CERN Document Server

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.

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

111

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

CERN Document Server

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

Gloukhov, N P; CERN. Geneva

1996-01-01

112

Hadron structure in the ladder model  

International Nuclear Information System (INIS)

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

113

Multiinstanton ladders in Baryon Number Violating Processes  

OpenAIRE

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

Lazarides, G.; Vlachos, N. D.

1995-01-01

114

From quantum ladder climbing to classical autoresonance  

International Nuclear Information System (INIS)

The autoresonance phenomenon allows excitation of a classical, oscillatory nonlinear system to high energies by using a weak, chirped frequency forcing. Ladder climbing is its counterpart in quantum mechanics. Here, for the first time to our knowledge, conditions for the transition from the quantum to the classical regimes are outlined. The similarities and differences between the two approaches are presented

115

Fermion-boson scattering in ladder approximation  

International Nuclear Information System (INIS)

A method of calculation of forward scattering amplitude for fermions and scalar bosons with exchanging of scalar particle is suggested. The Bethe-Salpeter ladder equation for the imaginary part of the amplitude is constructed and a solution in Regge asymptotical form is found and the corrections to the amplitude due to the exit from mass shell are calculated. (author). 8 refs

116

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

Scientific Electronic Library Online (English)

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

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

2014-06-01

117

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

Energy Technology Data Exchange (ETDEWEB)

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

Olsen, Erik

2009-09-01

118

Design for end-user acceptance: requirements for work clothing for fishermen in Mediterranean and northern fishing grounds.  

Science.gov (United States)

Fishing is one of the most dangerous occupations, and as many as 24,000 fishermen around the world suffer fatal injuries or drowning at sea every year. Although fishermen in the European fishing fleet work in harsh and dangerous environments, many fishermen do not use personal protective clothing and buoyancy aids due to reduced work comfort and poor functionality. This emphasizes the importance of designing work clothing and personal protective equipment (PPE) with functionality that matches the fishermen's needs. The aim of this study was to identify the requirements for work clothing in terms of comfort, protection, and safety for fishermen operating in northern fishing grounds and in the Mediterranean. Furthermore, we investigated whether fishermen in the Mediterranean prioritize work-clothing requirements differently from fishermen in northern fishing grounds. Interviews and observations of fishermen provided us with the requirements for work clothing for fishermen. A questionnaire was then distributed to a selection of European fishermen. The study showed that fishermen operating in the Mediterranean prioritized their requirements differently from fishermen in northern fishing grounds. There was good agreement on requirements regarding work comfort. Safety requirements, such as integrated buoyancy, were ranked as less important by the Mediterranean fishermen compared to fishermen in northern fishing grounds. The results of this study provide a basis for the development of work clothing and PPE for fishermen. Work clothing and PPE that fulfil the requirements are likely to obtain end-user acceptance and thus improve safety for fishermen at sea. PMID:22669810

Storholmen, Tore Christian Bjorsvik; Naesgaard, Ole Petter; Faerevik, Hilde; Reitan, Jarl; Holmen, Ingunn Marie; Reinertsen, Randi Eidsmo

2012-01-01

119

Gauge theory description of spin ladders  

Energy Technology Data Exchange (ETDEWEB)

An s=1/2 antiferromagnetic spin chain is equivalent to the two-flavour massless Schwinger model in a uniform background charge density in the strong coupling regime. The gapless mode of the spin chain is represented by a massless boson of the Schwinger model. In a two-leg spin ladder system the massless boson acquires a finite mass due to inter-chain interactions. The gap energy is found to be about 0.36 vertical bar J' vertical bar when the inter-chain Heisenberg coupling J' is small compared with the intra-chain Heisenberg coupling. It is also shown that a cyclically symmetric N{sub l}-leg ladder system is gapless or gapful for an odd or even N{sub l}, respectively. (author). Letter-to-the-editor.

Hosotani, Yutaka [School of Physics and Astronomy, University of Minnesota, Minneapolis, MN (United States)

1997-11-21

120

Stripe formation in doped Hubbard ladders  

CERN Document Server

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.

Hager, G; Jeckelmann, E; Fehske, H

2004-01-01

121

Raman Scattering cross section of Spin Ladders  

OpenAIRE

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

Orignac, E.; Citro, R.

2000-01-01

122

Magnetization Properties of Some Quantum Spin Ladders  

CERN Document Server

The experimental realization of various spin ladder systems has prompted their detailed theoretical investigations. Here we study the evolution of ground state magnetization with an external magnetic field for two different antiferromagnetic systems: a three-legged spin-1/2 ladder, and a two-legged spin-1/2 ladder with an additional diagonal interaction. The finite system density-matrix renormalization group method is employed for numerical studies of the three-chain system, and an effective low-energy Hamiltonian is used in the limit of strong interchain coupling to study the two- and three-chain systems. The three-chain system has a magnetization plateau at one-third of the saturation magnetization. The two-chain system has a plateau at zero magnetization due to a gap above the singlet ground state. It also has a plateau at half of the saturation magnetization for a certain range of values of the couplings. We study the regions of transitions between plateaus numerically and analytically, and find that they...

Tandon, K N; Pati, S K; Ramasesha, S; Sen, D; Tandon, Kunj; Lal, Siddhartha; Pati, Swapan K.; Sen, Diptiman

1999-01-01

123

Braess like Paradox on Ladder Network  

CERN Document Server

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...

Toyota, Norihito

2015-01-01

124

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

125

Mathematical modelling of the LC-Ladder and capacitive shunt-shunt feedback LNA topology  

OpenAIRE

In this paper a new low noise amplifier configuration is proposed to achieve wideband operation. This configuration consists of an LC-ladder filter and a common-emitter stage employing shunt-shunt capacitive feedback to realize wideband matching. Design equations for this configuration are derived, as well as equations for the important performance measures namely noise figure, gain and IIP3. The results of a design for achieving typical low noise amplifier specifications in the ultra-wideban...

Weststrate, Marnus; Sinha, Saurabh

2009-01-01

126

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

Directory of Open Access Journals (Sweden)

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

Sheng Chih Shen

2013-03-01

127

Comparative phylogeography in Fijian coral reef fishes: a multi-taxa approach towards marine reserve design.  

Science.gov (United States)

Delineating barriers to connectivity is important in marine reserve design as they describe the strength and number of connections among a reserve's constituent parts, and ultimately help characterize the resilience of the system to perturbations at each node. Here we demonstrate the utility of multi-taxa phylogeography in the design of a system of marine protected areas within Fiji. Gathering mtDNA control region data from five species of coral reef fish in five genera and two families, we find a range of population structure patterns, from those experiencing little (Chrysiptera talboti, Halichoeres hortulanus, and Pomacentrus maafu), to moderate (Amphiprion barberi, ?(st) = 0.14 and Amblyglyphidodon orbicularis ?(st) = 0.05) barriers to dispersal. Furthermore estimates of gene flow over ecological time scales suggest species-specific, asymmetric migration among the regions within Fiji. The diversity among species-specific results underscores the limitations of generalizing from single-taxon studies, including the inability to differentiate between a species-specific result and a replication of concordant phylogeographic patterns, and suggests that greater taxonomic coverage results in greater resolution of community dynamics within Fiji. Our results indicate that the Fijian reefs should not be managed as a single unit, and that closely related species can express dramatically different levels of population connectivity. PMID:23118892

Drew, Joshua A; Barber, Paul H

2012-01-01

128

Theoretical and experimental studies on 104 MHz ladder IH-RFQ accelerator  

International Nuclear Information System (INIS)

To study feasibilities of RFQ-based ion implantation and accelerator mass spectroscopy (AMS), a 104 MHz ladder type IH radio-frequency quadrupole (Ladder IH-RFQ) accelerator has been developed. According to beam dynamics design, it is able to accelerate ions with mass-to-charge ratio up to 14 from 2.9 keV/u to 35.7 keV/u. As a specific feature, the output beam energy spread is as low as 0.6% realized by using internal discrete bunching method. A rod-type RFQ structure, i.e. ladder IH-RFQ is adopted, taking advantage of its mechanical stability and symmetric inter-electrode field. Power test shows that specific shunt impedance of the constructed cavity reaches 178 k? m. During the beam commissioning, 210 ?A 4He+ beam has been obtained, and the transmission efficiency is better than 70% at current of several tens ?A. The ladder IH-RFQ is proved to be very suitable for operating frequency above 100 MHz for light ions

129

Theoretical and experimental studies on 104 MHz ladder IH-RFQ accelerator  

Science.gov (United States)

To study feasibilities of RFQ-based ion implantation and accelerator mass spectroscopy (AMS), a 104 MHz ladder type IH radio-frequency quadrupole (Ladder IH-RFQ) accelerator has been developed. According to beam dynamics design, it is able to accelerate ions with mass-to-charge ratio up to 14 from 2.9 keV/u to 35.7 keV/u. As a specific feature, the output beam energy spread is as low as 0.6% realized by using internal discrete bunching method. A rod-type RFQ structure, i.e. ladder IH-RFQ is adopted, taking advantage of its mechanical stability and symmetric inter-electrode field. Power test shows that specific shunt impedance of the constructed cavity reaches 178 k? m. During the beam commissioning, 210 ?A 4He+ beam has been obtained, and the transmission efficiency is better than 70% at current of several tens ?A. The ladder IH-RFQ is proved to be very suitable for operating frequency above 100 MHz for light ions.

Nie, Y. C.; Lu, Y. R.; Gao, S. L.; Yan, X. Q.; Guo, Z. Y.; Chen, J. E.

2014-02-01

130

Theoretical and experimental studies on 104 MHz ladder IH-RFQ accelerator  

Energy Technology Data Exchange (ETDEWEB)

To study feasibilities of RFQ-based ion implantation and accelerator mass spectroscopy (AMS), a 104 MHz ladder type IH radio-frequency quadrupole (Ladder IH-RFQ) accelerator has been developed. According to beam dynamics design, it is able to accelerate ions with mass-to-charge ratio up to 14 from 2.9 keV/u to 35.7 keV/u. As a specific feature, the output beam energy spread is as low as 0.6% realized by using internal discrete bunching method. A rod-type RFQ structure, i.e. ladder IH-RFQ is adopted, taking advantage of its mechanical stability and symmetric inter-electrode field. Power test shows that specific shunt impedance of the constructed cavity reaches 178 k? m. During the beam commissioning, 210 ?A {sup 4}He{sup +} beam has been obtained, and the transmission efficiency is better than 70% at current of several tens ?A. The ladder IH-RFQ is proved to be very suitable for operating frequency above 100 MHz for light ions.

Nie, Y.C., E-mail: ycnie@pku.edu.cn [State Key Lab of Nuclear Physics and Technology, Peking University, Beijing 100871 (China); DESY, Hamburg 22607 (Germany); Lu, Y.R.; Gao, S.L.; Yan, X.Q.; Guo, Z.Y.; Chen, J.E. [State Key Lab of Nuclear Physics and Technology, Peking University, Beijing 100871 (China)

2014-02-11

131

A Dream or Jacob's Ladder  

OpenAIRE

Geddes spent the majority of her childhood in Belfast where she was later educated as an illustrator and graphic designer at the Belfast School of Art. In 1910 she began attending William Orpen's classes at the Dublin Metropolitan School and exhibiting at the Arts and Crafts Society. She also exhibited at the Louvre, the Royal Hibernian Academy, Society of Scottish Artists, the Ulster Academy and others. She is best known for her stained glass works, many of which were executed with An Túr G...

Geddes, Wilhelmina Margaret

1987-01-01

132

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

International Nuclear Information System (INIS)

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

133

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

Energy Technology Data Exchange (ETDEWEB)

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

Hildebrand, S.G. (ed.)

1980-08-01

134

Design and demonstration of a fish robot actuated by a SMA-driven actuation system  

Science.gov (United States)

This paper presents a concept of a fish robot actuated by an SMA-based actuator. The bending-type actuator system is composed of a 0.1mm diameter SMA wire and a 0.5mm thick glass/epoxy strip. The SMA wire is installed to the bent composite strip. The actuator can produce about 200gf of blocking force and 3.5mm displacement at the center of the glass/epoxy strip. The bending motion of the actuator is converted into the tail-beat motion of a fish robot through a linkage system. The fish robot is evaluated by measuring the tail-beat angle, swimming speed and thrust produced by the fish robot. The tail-beat angle is about 20° and the maximum swimming speed is about 1.6cm/s. The measured thrust is about 0.4gf when the fish robot is operated at 0.9Hz.

Le, Chan H.; Nguyen, Quang S.; Park, Hoon C.

2010-04-01

135

Education System and the "Ladder of Success"  

OpenAIRE

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...

Ueda, Akiko

2004-01-01

136

Magnetization and concurrence on decorated zigzag ladder  

International Nuclear Information System (INIS)

Using Heisenberg model with two-, three- and four-site exchange interactions, by means of variational mean-feld like treatment based on Gibbs-Bogoliubov inequality the magnetic properties and concurrence (measure of pairwise thermal entanglement) on decorated zigzag ladder are studied. We have found that in the antiferromagnetic region behaviour of the concurrence coincides with the magnetic susceptibility one. With absence of external magnetic feld the dependence of magnetization from temperature plotted and shown that system undergo second order phase transition in some critical temperature.

137

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)

138

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-12-30

139

DESIGN AND EVALUATION OF ONE PROTOTYPE OF FISH CULTURE SYSTEM IN SAN CLEMENTE DE TERAPA, MOCTEZUMA, SONORA  

OpenAIRE

This research will help to design a system of Oreochromis niloticus intensive fish farming in the community San Clemente de Térapa, Moctezuma, Sonora, México, using thermal water from a perennial spring in circular ponds during 12 weeks. Production of O. niloticus is a common practice in aquaculture to local consume, because this specie has an adequate growth rate and feed conversion, also resist critical environmental conditions like temperature, anoxia, and tolerance to water hardness and...

María de la Paz Montañez-Armenta; Uriel Angulo-Corrales; Hugo Silva-Kurumiya; Diana Vázquez-Soto

2011-01-01

140

Quantifying Ladder Fuels: A New Approach Using LiDAR  

Directory of Open Access Journals (Sweden)

Full Text Available We investigated the relationship between LiDAR and ladder fuels in the northern Sierra Nevada, California USA. Ladder fuels are often targeted in hazardous fuel reduction treatments due to their role in propagating fire from the forest floor to tree crowns. Despite their importance, ladder fuels are difficult to quantify. One common approach is to calculate canopy base height, but this has many potential sources of error. LiDAR may be a way forward to better characterize ladder fuels, but has only been used to address this question peripherally and in only a few instances. After establishing that landscape fuel treatments reduced canopy and ladder fuels at our site, we tested which LiDAR-derived metrics best differentiated treated from untreated areas. The percent cover between 2 and 4 m had the most explanatory power to distinguish treated from untreated pixels across a range of spatial scales. When compared to independent plot-based measures of ladder fuel classes, this metric differentiated between high and low levels of ladder fuels. These findings point to several immediate applications for land managers and suggest new avenues of study that could lead to possible improvements in the way that we model wildfire behavior across forested landscapes in the US.

Heather A. Kramer

2014-06-01

141

Superconductivity in doped two-leg ladder cuprates  

International Nuclear Information System (INIS)

Within the t-J ladder model, superconductivity with a modified d-wave symmetry in doped two-leg ladder cuprates is investigated based on the kinetic energy driven superconducting mechanism. It is shown that the spin-liquid ground-state at the half-filling evolves into the superconducting ground-state upon doping. In analogy to the doping dependence of the superconducting transition temperature in the planar cuprate superconductors, the superconducting transition temperature in doped two-leg ladder cuprates increases with increasing doping in the underdoped regime, and reaches a maximum in the optimal doping, then decreases in the overdoped regime

142

Diverging Heisenberg spin ladders: ground state and low energy excitations  

Energy Technology Data Exchange (ETDEWEB)

We consider a two-leg ladder system with interactions varying from constant rung coupling to systematic diminishing of rung interactions leading to diverging chains. We compare and contrast their ground state and excitation characteristics using density matrix renormalization group methods. We find that the finite spin gap in a constant coupling ladder develops into a gapless excitation with slight diminishing of the distance dependent coupling. Varying the spatial range of the rung coupling, we derive the effective length scale of triplet excitations in these ladder classes of systems. (fast track communication)

Parihari, Debabrata; Pati, Swapan K [Theoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064 (India)

2007-04-30

143

E3: Education, Experience, Employment The Economic Ladder to Success  

Energy Technology Data Exchange (ETDEWEB)

Science, Technology, Engineering, and Math (STEM) literate citizenry is critical for Idaho's economy to effectively compete and grow in today's global marketplace and enhance Idaho workforce capabilities. Idaho's blueprint presents a collaboration design developed by a group of Idaho stakeholders including state level (STEM) educators, state and federal government, other agencies, and industry across the state. The purpose the Idaho Learn and Earn Blueprint Design is to describe a comprehensive plan for improving STEM education in Idaho through a collaborative partnerships and a series of grant supported projects underpinning this strategic design process building pathways to overcome hurdles in today's economy, and moving communities and families up their economic ladder. The Idaho Learn and Earn Blueprint Design focuses on three industry sectors; energy, advanced manufacturing, and health care. All are important in Idaho and have room for job growth potential among both displaced workers and graduates. Representatives from each sector are members of the design team and assist in developing grants and implementing the actions outlined in the design as the program goes forward. Idaho's current programs are generally institution specific. Each of the state's two-year colleges, along with regional groups and employers, are already working towards improving STEM education across the state. A key aspect of this design is to bring these groups together to focus on four unique goals: (1) Providing industry driven curriculum directly tied to skill based career needs; (2) Enhancing collaboration among stakeholders; (3) Providing access to learn and earn programs; and (4) Improving public and student awareness and interest in targeted industry sector career and educational opportunities.

Anne L Seifert

2011-10-01

144

Entanglement in resonating valence bond states: ladder versus isotropic lattices  

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-11-18

145

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

Energy Technology Data Exchange (ETDEWEB)

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.

Chamness, Mickie A. [Pacific Northwest National Laboratory

2008-08-29

146

Fractal ladder models and power law wave equations  

OpenAIRE

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 s...

Kelly, James F.; Mcgough, Robert J.

2009-01-01

147

Piezoelectric biosensor with a ladder polymer substrate coating  

Science.gov (United States)

A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor.

Renschler, Clifford L. (Tijeras, NM); White, Christine A. (Albuquerque, NM); Carter, Robert M. (New Orleans, LA)

1998-01-01

148

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-12-01

149

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

150

DESIGN AND EVALUATION OF ONE PROTOTYPE OF FISH CULTURE SYSTEM IN SAN CLEMENTE DE TERAPA, MOCTEZUMA, SONORA  

Directory of Open Access Journals (Sweden)

Full Text Available This research will help to design a system of Oreochromis niloticus intensive fish farming in the community San Clemente de Térapa, Moctezuma, Sonora, México, using thermal water from a perennial spring in circular ponds during 12 weeks. Production of O. niloticus is a common practice in aquaculture to local consume, because this specie has an adequate growth rate and feed conversion, also resist critical environmental conditions like temperature, anoxia, and tolerance to water hardness and high organic matter content. This design was according to quality and quantity of water. Body growth and survive was measured, also the farming viability under the particular conditions of the prototype design. Two circular ponds of 4.5 m and 3 m in diameter were installed, where were introduced 800 and 400 masculinized “young fish”, whit an average weight of 0.84 and 0.54 g respectively. Biometrics measured and physicochemical parameters of water were assessment (temperature, dissolved oxygen and pH. At the end of the culture was obtained a survive rate of 98.5% and 98.25 % en each pond respectively, an excellent adaptation of the organisms and an acceptable body mass. This study shows is possible to get positive results under these conditions.

María de la Paz Montañez-Armenta

2011-05-01

151

Instabilities of coupled Cu2O5 ladders  

Science.gov (United States)

The spin-ladder compound Sr14-xCaxCu24O41 has a complex phase diagram including charge-density-wave order as well as unconventional superconductivity under high pressure. Due to its quasi-one-dimensional natureootnotetextS. Lee, J. B. Marston, J. O. Fjaerestad, Phys. Rev. B 72, 075126. fundamental questions about the high-Tc cuprates might be more easily addressed in this context. However, due to the spatial proximity of neighboring ladders inter-ladder Coulomb repulsion as well as hopping between ladders might still be important. Using the functional renormalization groupootnotetextM. Salmhofer and C. Honerkamp, Prog. Theor. Physics 105, 1 (2001). and an analysis of generalized susceptibilities ootnotetextD. Zanchi and H. J. Schulz, Phys. Rev. B 61, 13609 (2000); C. J. Halboth and W. Metzner, Phys. Rev. Lett. 85, 5162 (2000)., we study a model of coupled Cu2O5 ladders ootnotetextK. Wohlfeld, A. M. Oles, and G. A. Sawatzky, Phys. Rev. B 75, 180501(R) (2007).. We investigate instabilities towards charge, spin, and pairing order as a function of hole doping, inter-ladder hopping, and interaction strength starting from experimentally relevant hopping parametersootnotetextT. F. A. Müller, et al., Phys. Rev. B 57, R12655 (1998)..

Schuetz, Florian; Marston, Brad

2008-03-01

152

Giant Stark effect in double-stranded porphyrin ladder polymers  

Science.gov (United States)

Using the first-principles calculations, we have investigated the stability and the electronic structure of two types of recently synthesized one-dimensional nanoribbons, i.e., double-stranded zinc(II) porphyrin ladder polymer (LADDER) arrays. First, electronic structure calculations were used to show that the LADDER is a semiconductor. Most importantly, the application of a transverse electric field significantly reduces the band gap of the LADDER, ultimately converting the LADDER to a metal at a field strength of 0.1 V/Å. The giant Stark effect in this case is almost as strong as that in boron nitride nanotubes and nanoribbons. In the presence of an electric field, hole conduction and electronic conduction will occur entirely through spatially separated strands, rendering these materials useful for nanoelectronic devices. Second, the substitution of hydrogen atoms in the porphyrin units or that of zinc ions with other kinds of chemical species is found to increase the binding strength of the LADDER and reduce the band gap.

Pramanik, Anup; Kang, Hong Seok

2011-03-01

153

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

Directory of Open Access Journals (Sweden)

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

Marlene Sofia Arcifa

2012-10-01

154

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

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese 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.

Marlene Sofia, Arcifa; André Luiz Henríques, Esguícero.

2012-10-01

155

Walla Walla River Basin Fish Screens Evaluations, 2006 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

Pacific Northwest National Laboratory evaluated Gardena Farms, Little Walla Walla, and Garden City/Lowden II Phase II fish screen facilities and provided underwater videography beneath a leaking rubber dam in the Walla Walla River basin in 2006. Evaluations of the fish screen facilities took place in early May 2006, when juvenile salmonids are generally outmigrating. At the Gardena Farms site, extended high river levels caused accumulations of debris and sediment in the forebay. This debris covered parts of the bottom drum seals, which could lead to early deterioration of the seals and drum screen. Approach velocities were excessive at the upstream corners of most of the drums, leading to 14% of the total approach velocities exceeding 0.4 feet per second (ft/s). Consequently, the approach velocities did not meet National Marine Fisheries Service (NMFS) design criteria guidelines for juvenile fish screens. The Little Walla Walla site was found to be in good condition, with all approach, sweep, and bypass velocities within NMFS criteria. Sediment buildup was minor and did not affect the effectiveness of the screens. At Garden City/Lowden II, 94% of approach velocities met NMFS criteria of 0.4 ft/s at any time. Sweep velocities increased toward the fish ladder. The air-burst mechanism appears to keep large debris off the screens, although it does not prevent algae and periphyton from growing on the screen face, especially near the bottom of the screens. In August 2006, the Gardena Farm Irrigation District personnel requested that we look for a leak beneath the inflatable rubber dam at the Garden City/Lowden II site that was preventing water movement through the fish ladder. Using our underwater video equipment, we were able to find a gap in the sheet piling beneath the dam. Erosion of the riverbed was occurring around this gap, allowing water and cobbles to move beneath the dam. The construction engineers and irrigation district staff were able to use the video footage to resolve the problem within a couple weeks. We had hoped to also evaluate the effectiveness of modifications to louvers behind the Nursery Bridge screens when flows were higher than 350 cubic feet per second, (cfs) but were unable to do so. Based on the one measurement made in early 2006 after the modified louvers were set, it appears the modified louvers may help reduce approach velocities. The auxiliary supply water system gates also control water through the screens. Evaluating the effect of different combinations of gate and louver positions on approach velocities through the screens may help identify optimum settings for both at different river discharges.

Chamness, Mickie; Abernethy, Scott; Tunnicliffe, Cherylyn [Pacific Northwest National Laboratory

2007-01-01

156

76 FR 60379 - Hunting and Fishing  

Science.gov (United States)

...Fish and Wildlife Service 50 CFR Part 32 Hunting and Fishing CFR Correction In Title 50...National Wildlife Refuge * * * * * 0 D. Sport Fishing. We allow fishing on designated...fishing. 0 3. We only allow hook and line sport fishing utilizing rod and reel or...

2011-09-29

157

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 ...

158

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

OpenAIRE

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...

Rossi, Claudio; Coral Cuellar, William; Colorado Montan?o, Julia?n; Barrientos Cruz, Antonio

2011-01-01

159

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

Directory of Open Access Journals (Sweden)

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

Coll-Serrano, Vicente

2012-01-01

160

Ladder Operators for Lamé Spheroconal Harmonic Polynomials  

Directory of Open Access Journals (Sweden)

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

Ricardo Méndez-Fragoso

2012-10-01

161

Economic integration in the quality ladder model  

Directory of Open Access Journals (Sweden)

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

Eduardo Correia de Souza

2008-12-01

162

Ladder-Like Amplification of the Type I Interferon Gene Cluster in the Human Osteosarcoma Cell Line MG63  

OpenAIRE

The organization of the type I interferon (IFN) gene cluster (9p21.3) was studied in a human osteosarcoma cell line (MG63). Array comparative genomic hybridization (aCGH) showed an amplification of ~six-fold which ended at both ends of the gene cluster with a deletion that extended throughout the 9p21.3 band. Spectral karyotyping (SKY) combined with fluorescence in situ hybridization (FISH) identified an arrangement of the gene cluster in a ladder-like array of 5–7 “bands” spanning a si...

Marella, Narasimha Rao V.; Zeitz, Michael J.; Malyavantham, Kishore S.; Pliss, Artem; Matsui, Sei-ichi; Goetze, Sandra; Bode, Juergen; Raska, Ivan; Berezney, Ronald

2008-01-01

163

Reynolds shear-stress and velocity: positive biological response of neotropical fishes to hydraulic parameters in a vertical slot fishway  

Directory of Open Access Journals (Sweden)

Full Text Available The barriers created by dams can cause negative impacts to aquatic communities, and migratory fish species are directly affected. Fishways have been developed to allow the upstream passage of fishes through dams. In Brazil, after the implementation of environmental laws, these structures have been built based on European and American fishway designs. Studies have shown selectivity for different neotropical fishes in some Brazilian fishways, and the main challenge has been to promote upstream passage of a large number of diverse fish species. The patterns of flow circulation within the fish ladder may explain fish selectivity although few studies detail the fish response to hydraulic characteristics of fish ladder flow. This paper presents a laboratory study, where a vertical slot fishway was built in a hydraulic flume and the behavior of two neotropical fish species (Leporinus reinhardti and Pimelodus maculatus were analyzed. The structure of flow was expressed in terms of mean velocity, Reynolds shear-stress and velocity fluctuation fields. The individuals of Leporinus reinhardti had higher passage success than Pimelodus maculatus in the laboratory flume. Both species preferred areas of low to zero Reynolds shear-stress values. In addition, different preferences were observed for these species concerning the horizontal components of velocity fluctuation.Interrupções em rios, como as causadas por barragens, provocam impactos negativos sobre as comunidades aquáticas e as espécies migratórias de peixes são diretamente afetadas. A fim de permitir a passagem de peixes, mecanismos de transposição são construídos junto a barramentos. No Brasil, após a implantação de leis ambientais, estas estruturas passaram a ser amplamente construídas e foram baseadas em projetos desenvolvidos na Europa e na América do Norte. Análises de mecanismos já construídos têm mostrado grande seletividade para espécies neotropicais e as demandas da diversa fauna de peixes neotropical são apresentadas como principal desafio ao projeto de passagens para peixes. Os padrões de escoamento dentro de escadas para peixes podem explicar a seletividade destes mecanismos, mas poucos estudos detalham a resposta dos peixes às características hidráulicas encontradas dentro das escadas. Este estudo apresenta uma análise realizada em um laboratório onde foi construída uma escada do tipo ranhura vertical e analisados os comportamentos de duas espécies neotropicais (Leporinus reinhardti e Pimelodus maculatus. O escoamento foi estudado considerando os campos de velocidade média, tensão cisalhante de Reynolds e flutuações de velocidades. Os indivíduos da espécie Leporinus reinhardti apresentaram maior sucesso de passagem do que os da espécie Pimelodus maculatus. Ambas as espécies preferiram áreas de tensão de Reynolds igual a zero. Além disso, diferentes preferências foram observadas para cada espécie em relação às componentes horizontais da flutuação da velocidade.

Bernardo Alan de Freitas Duarte

2012-10-01

164

Reynolds shear-stress and velocity: positive biological response of neotropical fishes to hydraulic parameters in a vertical slot fishway  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Interrupções em rios, como as causadas por barragens, provocam impactos negativos sobre as comunidades aquáticas e as espécies migratórias de peixes são diretamente afetadas. A fim de permitir a passagem de peixes, mecanismos de transposição são construídos junto a barramentos. No Brasil, após a imp [...] lantação de leis ambientais, estas estruturas passaram a ser amplamente construídas e foram baseadas em projetos desenvolvidos na Europa e na América do Norte. Análises de mecanismos já construídos têm mostrado grande seletividade para espécies neotropicais e as demandas da diversa fauna de peixes neotropical são apresentadas como principal desafio ao projeto de passagens para peixes. Os padrões de escoamento dentro de escadas para peixes podem explicar a seletividade destes mecanismos, mas poucos estudos detalham a resposta dos peixes às características hidráulicas encontradas dentro das escadas. Este estudo apresenta uma análise realizada em um laboratório onde foi construída uma escada do tipo ranhura vertical e analisados os comportamentos de duas espécies neotropicais (Leporinus reinhardti e Pimelodus maculatus). O escoamento foi estudado considerando os campos de velocidade média, tensão cisalhante de Reynolds e flutuações de velocidades. Os indivíduos da espécie Leporinus reinhardti apresentaram maior sucesso de passagem do que os da espécie Pimelodus maculatus. Ambas as espécies preferiram áreas de tensão de Reynolds igual a zero. Além disso, diferentes preferências foram observadas para cada espécie em relação às componentes horizontais da flutuação da velocidade. Abstract in english The barriers created by dams can cause negative impacts to aquatic communities, and migratory fish species are directly affected. Fishways have been developed to allow the upstream passage of fishes through dams. In Brazil, after the implementation of environmental laws, these structures have been b [...] uilt based on European and American fishway designs. Studies have shown selectivity for different neotropical fishes in some Brazilian fishways, and the main challenge has been to promote upstream passage of a large number of diverse fish species. The patterns of flow circulation within the fish ladder may explain fish selectivity although few studies detail the fish response to hydraulic characteristics of fish ladder flow. This paper presents a laboratory study, where a vertical slot fishway was built in a hydraulic flume and the behavior of two neotropical fish species (Leporinus reinhardti and Pimelodus maculatus) were analyzed. The structure of flow was expressed in terms of mean velocity, Reynolds shear-stress and velocity fluctuation fields. The individuals of Leporinus reinhardti had higher passage success than Pimelodus maculatus in the laboratory flume. Both species preferred areas of low to zero Reynolds shear-stress values. In addition, different preferences were observed for these species concerning the horizontal components of velocity fluctuation.

Bernardo Alan de Freitas, Duarte; Isabella Cristina Resende, Ramos; Hersília de Andrade e, Santos.

2012-10-01

165

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).  

Science.gov (United States)

...of ladders, scaffolds, and towers shall be of adequate size...inches for mobile scaffolds (towers). Ladder stands shall have... (iii) The supporting structure for the work level shall be...level platform of scaffolds (towers) shall be of wood,...

2010-07-01

166

Incommensurate dynamics of resonant breathers in Josephson junction ladders  

CERN Document Server

We present theoretical and experimental studies of resonant localized resistive states in a Josephson junction ladder. These complex breather states are obtained by tuning the breather frequency into the upper band of linear electromagnetic oscillations of the ladder. Their prominent feature is the appearance of resonant steps in the current-voltage (I-V) characteristics. We have found the resonant breather-like states displaying incommensurate dynamics. Numerical simulations show that these incommensurate resonant breathers persist for very low values of damping. Qualitatively similar incommensurate breather states are observed in experiments performed with Nb-based Josephson ladders. We explain the appearance of these states with the help of resonance-induced hysteresis features in the I-V dependence.

Fistul, M V; Flach, S; Schuster, M; Ustinov, A V

2001-01-01

167

Fractal ladder models and power law wave equations.  

Science.gov (United States)

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

Kelly, James F; McGough, Robert J

2009-10-01

168

Ab initio study of ladder-type polymers polythiophene and polypyrrole  

OpenAIRE

This article presents an \\textit{ab initio} study of four polymers, polythiophene, polypyrrole, ladder-type polythiophene, and ladder-type polypyrrole. Upon an analysis of the variation of the band gap when comparing the unconstrained and the ladder-type polymers, a discrepancy was found between the thiophene and the pyrrole polymer families. For polythiophene, the ladder-type polymer has a larger gap than the unconstrained polymer whereas the opposite is found for the pyrro...

Pesant, Simon; Boulanger, Paul; Co?te?, Michel; Ernzerhof, Matthias

2006-01-01

169

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

Science.gov (United States)

...the importation of live fish, fertilized eggs, and gametes. 93.902 Section 93...the importation of live fish, fertilized eggs, and gametes. (a) The following...ports of entry for live fish, fertilized eggs, and gametes of SVC-susceptible...

2010-01-01

170

Identification of topologically different valence bond states in spin ladders  

CERN Document Server

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

Nakamura, M

2003-01-01

171

Edge-reinforced random walk on a ladder  

OpenAIRE

We prove that the edge-reinforced random walk on the ladder ${\\mathbb{Z}\\times\\{1,2\\}}$ with initial weights $a>3/4$ is recurrent. The proof uses a known representation of the edge-reinforced random walk on a finite piece of the ladder as a random walk in a random environment. This environment is given by a marginal of a multicomponent Gibbsian process. A transfer operator technique and entropy estimates from statistical mechanics are used to analyze this Gibbsian process. F...

Merkl, F.; Rolles, Sww

2005-01-01

172

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

LENUS (Irish Health Repository)

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

Kennedy, Harry G

2011-09-01

173

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)

174

A snakes and ladders representation of stock prices and returns  

OpenAIRE

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

Gager, P.; Shackleton, M. B.

2009-01-01

175

Corrosion Control Specialist Career Ladder AFSC 53530, 53550, 53570, and 53690. Occupational Survey Report.  

Science.gov (United States)

The report describes the results of a detailed occupational survey of the corrosion control career ladder. Responses to a 457-task, time rating inventory from 1,015 personnel (representing 64 percent of the career field) were analyzed to produce seven specific findings and the career ladder structure. The career ladder includes a variety of jobs…

Air Force Occupational Measurement Center, Lackland AFB, TX.

176

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

Science.gov (United States)

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

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

2010-09-01

177

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.

178

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

DEFF Research Database (Denmark)

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

Christensen, AsbjØrn; Mosegaard, Henrik

2009-01-01

179

Color conductivity and ladder summation in hot QCD  

OpenAIRE

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

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

2000-01-01

180

Towards flavored bound states beyond rainbows and ladders  

Science.gov (United States)

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.

El-Bennich, B.; Rojas, E.; Paracha, M. A.; de Melo, J. P. B. C.

2014-11-01

181

Raman Response of Magnetic Excitations in Cuprate Ladders and Planes  

CERN Document Server

An unified picture for the Raman response of magnetic excitations in cuprate spin-ladder compounds is obtained by comparing calculated two-triplon Raman line-shapes with those of the prototypical compounds SrCu_2O_3 (Sr123), Sr_14Cu_24O_41 (Sr14), and La_6Ca_8Cu_24O_41 (La6Ca8). The theoretical model for the two-leg ladder contains Heisenberg exchange couplings J_parallel and J_perp plus an additional four-spin interaction J_cyc. Within this model Sr123 and Sr14 can be described by x:=J_parallel/J_perp=1.5, x_cyc:=J_cyc/J_perp=0.2, J_perp ^{Sr123}=1130 cm^{-1} and J_perp^{Sr14}=1080 cm^{-1}. The couplings found for La6Ca8 are x=1.2, x_cyc=0.2, and J_perp^{La6Ca8}=1130 cm^{-1}. The unexpected sharp two-triplon peak in the ladder materials compared to the undoped two-dimensional cuprates can be traced back to the anisotropy of the magnetic exchange in rung and leg direction. With the results obtained for the isotropic ladder we calculate the Raman line-shape of a two-dimensional square lattice using a toy model...

Schmidt, K P; Kuhlmann, U; Thomsen, C; L"offert, A; Gross, C; Assmus, W

2005-01-01

182

Antiferromagnetic Ising model saturation field entropies: ladders and kagome lattice  

CERN Document Server

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).

Varma, Vipin Kerala

2013-01-01

183

Competency-Based Nursing Career Ladder Model. Final Report.  

Science.gov (United States)

An open-entry/open-exit competency-based nursing career ladder model was developed to demonstrate the articulation process from high school through licensed vocational nursing (LVN), associate degree nursing (ADN), and baccalaureate degree-level nursing (BSN) programs. The model was based on data obtained from a review of the literature on (1)…

Wilson, Janie Menchaca; And Others

184

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

CERN Document Server

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.

Nieuwenhuis, T; Nieuwenhuis, Taco

1996-01-01

185

Fish FAQ  

Science.gov (United States)

Northeast Fisheries Science Center answers your question regarding all things fish. Hundreds of fish and other marine fauna questions are answered in the FAQ section. Site also links to several external fish FAQs, as well as other internal and external resources, including kids sites, fish images, species synopses, how to age a fish. The site also features a glossary of fish terms and insight into the different ways fish are caught.

186

The Effects of Laddering and Spinning in Underwriter Manipulation of IPOs  

Directory of Open Access Journals (Sweden)

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

Ludwig Chincarini

2012-09-01

187

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

Directory of Open Access Journals (Sweden)

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

Ayca Kangal

2013-04-01

188

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 ...

189

Vitamin content of fish and fish products consumed in Portugal  

OpenAIRE

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

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

2003-01-01

190

Improving fish survival through turbines  

International Nuclear Information System (INIS)

Much of what is known about fish passage through hydroturbines has been developed by studying migratory species of fish passing through large Kaplan turbine units. A review of the literature on previous fish passage research presented in the accompanying story illustrates that studies have focused on determining mortality levels, rather than identifying the causal mechanism involved. There is a need for understanding how turbine designs could be altered to improve fish passage conditions, how to retrofit existing units, and how proposed hydro plant operational changes may affect fish survival. The US Army Corps of Engineers has developed a research program to define biologically based engineering criteria for improving fish passage conditions. Turbine designs incorporating these criteria can be evaluated for their effects on fish survival, engineering issues, costs, and power production. The research program has the following objectives: To gain a thorough knowledge of the mechanisms of fish mortality; To define the biological sensitivities of key fish species to these mechanisms of mortality; To develop new turbine design criteria to reduce fish mortality; To construct prototype turbine designs, and to test these designs for fish passage, hydro-mechanical operation, and power production; and To identify construction and power costs associated with new turbine designs

191

Action–angle variables, ladder operators and coherent states  

International Nuclear Information System (INIS)

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

192

Bethe–Salpeter studies of mesons beyond rainbow-ladder  

Directory of Open Access Journals (Sweden)

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.

Williams R.

2010-04-01

193

Bethe-Salpeter studies of mesons beyond rainbow-ladder  

CERN Document Server

We investigate the masses of light mesons from a coupled system of Dyson-Schwinger and Bethe-Salpeter equations. The dominant non-Abelian and sub-leading Abelian contributions to the dressed quark-gluon vertex are explicitly taken into account. We also include unquenching effects in the form of hadronic resonance contributions via the back-reaction of pions. We construct the corresponding Bethe--Salpeter kernel that satisfies 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 different corrections beyond rainbow-ladder on the properties of mesons. We find that sub-leading Abelian corrections are further suppressed dynamically, and that our results supersede early qualitative predictions with significantly simpler truncation schemes.

Williams, Richard

2009-01-01

194

Action–angle variables, ladder operators and coherent states  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-07-30

195

Duality relations and exotic orders in electronic ladder systems  

CERN Document Server

We discuss duality relations in correlated electronic ladder systems to clarify mutual relations between various conventional and unconventional phases. For the generalized two-leg Hubbard ladder, we find two exact duality relations, and also one asymptotic relation which holds in the low-energy regime. These duality relations show that unconventional (exotic) density-wave orders such as staggered flux or circulating spin-current are directly mapped to conventional density-wave orders, which establishes the appearance of various exotic states with time-reversal and/or spin symmetry breaking. We also study duality relations in the SO(5) symmetry that was proposed to unify antiferromagnetism and d-wave superconductivity. We show that the same SO(5) symmetry also unifies circulating spin current order and s-wave superconductivity.

Momoi, T; Momoi, Tsutomu; Hikihara, Toshiya

2004-01-01

196

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

Scientific Electronic Library Online (English)

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

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

197

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

Directory of Open Access Journals (Sweden)

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

Aytaç Özgül

2011-01-01

198

Chirping a two-photon transition in a multistate ladder  

International Nuclear Information System (INIS)

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

199

Autonomous stochastic resonance in fully frustrated Josephson-junction ladders  

OpenAIRE

We investigate autonomous stochastic resonance in fully frustrated Josephson-junction ladders, which are driven by uniform constant currents. At zero temperature large currents induce oscillations between the two ground states, while for small currents the lattice potential forces the system to remain in one of the two states. At finite temperatures, on the other hand, oscillations between the two states develop even below the critical current; the signal-to-noise ratio is f...

Jeon, Gun Sang; Choi, M. Y.

2002-01-01

200

Novel organic-inorganic layered oxide with spin ladder structure  

OpenAIRE

Structural analysis of a layered manganese tungstate diaminoalkane hybrid series suggests that this compound forms a spin-5/2 spin-ladder structure. We use X-ray diffraction, electron microscopy and x-ray absorption spectroscopy results to infer the structure. DC magnetization of the manganese compound and a possible copper analogue appear to show that the manganese system behaves like 1-dimensional antiferromagnetic Heisenberg chains (i.e. $J_{\\parallel} \\gg J_{\\perp})$ whi...

Ingham, B.; Tallon, J. L.; Chong, S. V.; Liu, R. -s; Jang, L. -y

2005-01-01

201

Charge kinks as Raman scatterers in quarter-filled ladders  

CERN Document Server

Charge kinks are considered as fundamental excitations in quarter-filled charge-ordered ladders. The strength of the coupling of the kinks to the three-dimensional lattice depends on their energy. The integrated intensity of Raman scattering by kink-antikink pairs is proportional to $\\phi ^{5}$ or $\\phi ^{4},$ where $\\phi $ is the order parameter. The exponent is determined by the system parameters and by the strength of the electron-phonon coupling.

Sherman, E Y; Lemmens, P; Güntherodt, G; Van Loosdrecht, P H M

2001-01-01

202

Ising phases of Heisenberg ladders in a magnetic field  

OpenAIRE

We examine the influence of weak anisotropic interactions on the T=0 phase diagram of the frustrated two-leg Heisenberg ladder, a well-studied spin model exhibiting integer and fractional magnetization plateaux separated by gapless incommensurate states. We find that the Dzyaloshinskii--Moriya coupling may substantially modify the phase diagram so that the half-integer plateau and the surrounding gapless phases merge into a single Ising-ordered phase breaking the translation...

Penc, Karlo; Fouet, Jean-baptiste; Miyahara, Shin; Tchernyshyov, Oleg; Mila, Frederic

2007-01-01

203

Snakes and ladders in an inhomogeneous neural field model  

OpenAIRE

Continuous neural field models with inhomogeneous synaptic connectivities are known to support traveling fronts as well as stable bumps of localized activity. We analyze stationary localized structures in a neural field model with periodic modulation of the synaptic connectivity kernel and find that they are arranged in a snakes-and-ladders bifurcation structure. In the case of Heaviside firing rates, we construct analytically symmetric and asymmetric states and hence derive closed-form ex...

Avitabile, Daniele; Schmidt, Helmut

2014-01-01

204

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)

205

Novel organic-inorganic layered oxide with spin ladder structure  

CERN Document Server

Structural analysis of a layered manganese tungstate diaminoalkane hybrid series suggests that this compound forms a spin-5/2 spin-ladder structure. We use X-ray diffraction, electron microscopy and x-ray absorption spectroscopy results to infer the structure. DC magnetization of the manganese compound and a possible copper analogue appear to show that the manganese system behaves like 1-dimensional antiferromagnetic Heisenberg chains (i.e. $J_{\\parallel} \\gg J_{\\perp})$ while the copper system is fitted well by a $S = {1/2}$ spin ladder model, giving the parameters $g = 1.920 \\pm 0.008$, $J_{\\parallel}/k_B = -0.3 \\pm 1.4$K; $J_{\\perp}/k_B = 213.6 \\pm 1.1$K. The ability to tune adjacent inorganic layers of the hybrid materials by altering the length of the organic `spacer' molecules gives enormous promise for the use of these materials, especially when doped, to provide a greater understanding of spin ladder systems.

Ingham, B; Chong, S V; Liu, R S; Jang, L Y

2005-01-01

206

Field induced quantum phase transition in the anisotropic spin ladder  

International Nuclear Information System (INIS)

We have studied the quantum phase transition between antiferromagnetic and spin liquid phases for field induced quasi-one dimensional spin ladder model Hamiltonian. Using bond operator formalism, the original spin Hamiltonian is mapped to bosonic one. Green's function approach has been implemented to get the low energy spectrum and the corresponding structure factor. The critical field (Bc) for a fixed coupling exchange between two rungs is found based on the Bose–Einstein condensation of quasi-particles (triplons) which takes place when the spin excitation spectrum vanishes at the antiferromagnetic wave vector. We have investigated the effect of both intersite (?) and local (?) anisotropy on the critical field, critical coupling exchange and transverse static structure factor of the field induced quasi-one dimensional antiferromagnetic anisotropic spin ladder model at zero temperature. We have also studied the divergent behavior of static spin structure factor when magnetic field approaches the critical point. - Highlights: ? The calculation of quantum critical field of spin ladder Hamiltonian by Green's function approach. ? The study of behavior of energy gap of spin excitation spectrum versus field and anisotropies. ? The investigation of behavior of transverse structure factor in terms of magnetic field.

207

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

Scientific Electronic Library Online (English)

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

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

2011-06-01

208

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

Directory of Open Access Journals (Sweden)

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

Bruno Bordeaux-Rego

2011-04-01

209

Electronic transport through a ladder nanostructure in the presence of network defects  

Directory of Open Access Journals (Sweden)

Full Text Available  The present research studied the electronic transport of an ideal infinite ladder nanostructure 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.

M Mardaani

2012-06-01

210

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

Science.gov (United States)

... IMPORTATION OF CERTAIN ANIMALS, BIRDS, FISH, AND POULTRY, AND CERTAIN ANIMAL, BIRD, AND POULTRY PRODUCTS...SHIPPING CONTAINERS Aquatic Animal Species General Provisions for...Boston, MA; Newark, NJ; New York, NY; Portland,...

2010-01-01

211

Bose metals and insulators on multileg ladders with ring exchange  

Science.gov (United States)

We establish compelling evidence for the existence of new quasi-one-dimensional descendants of the d-wave Bose liquid (DBL), an exotic two-dimensional quantum phase of uncondensed itinerant bosons characterized by surfaces of gapless excitations in momentum space [O. I. Motrunich and M. P. A. Fisher, Phys. Rev. BPLRBAQ1098-012110.1103/PhysRevB.75.235116 75, 235116 (2007)]. In particular, motivated by a strong-coupling analysis of the gauge theory for the DBL, we study a model of hard-core bosons moving on the N-leg square ladder with frustrating four-site ring exchange. Here, we focus on four- and three-leg systems where we have identified two novel phases: a compressible gapless Bose metal on the four-leg ladder and an incompressible gapless Mott insulator on the three-leg ladder. The former is conducting along the ladder and has five gapless modes, one more than the number of legs. This represents a significant step forward in establishing the potential stability of the DBL in two dimensions. The latter, on the other hand, is a fundamentally quasi-one-dimensional phase that is insulating along the ladder but has two gapless modes and incommensurate power-law transverse density-density correlations. While we have already presented results on this latter phase elsewhere [M. S. Block , Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.106.046402 106, 046402 (2011)], we will expand upon those results in this work. In both cases, we can understand the nature of the phase using slave-particle-inspired variational wave functions consisting of a product of two distinct Slater determinants, the properties of which compare impressively well to a density matrix renormalization group solution of the model Hamiltonian. Stability arguments are made in favor of both quantum phases by accessing the universal low-energy physics with a bosonization analysis of the appropriate quasi-1D gauge theory. We will briefly discuss the potential relevance of these findings to high-temperature superconductors, cold atomic gases, and frustrated quantum magnets.

Mishmash, Ryan V.; Block, Matthew S.; Kaul, Ribhu K.; Sheng, D. N.; Motrunich, Olexei I.; Fisher, Matthew P. A.

2011-12-01

212

Charge Excitations in Two-Leg Ladders: A tDMRG Approach  

Energy Technology Data Exchange (ETDEWEB)

Abstract We study the dynamics of holon doublon pairs in two-leg Hubbard ladders with the time-dependent Density Matrix Renormalization-Group approach. Benchmark results show that the Krylov algorithm is well suited to calculate the time dependence of observables in these systems. Furthermore, we show that the dynamics of the holon doublon depend strongly on the coupling asymmetry within the ladder, indicating that the ladder geometry plays a role in the decay of these elementary charge excitations.

Dias da Silva, Luis [University of Sao Paulo, BRAZIL; Alvarez, Gonzalo [ORNL; Summers, Michael Stuart [ORNL; Dagotto, Elbio R [ORNL

2013-01-01

213

Walla Walla River Fish Passage Operations Program, 2002-2003 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

In the late 1990's, 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 initiating trap and haul efforts. 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 2002-2003 project year, there were 545 adult summer steelhead (Oncorhynchus mykiss), 29 adult bull trout (Salvelinus confluentus); 1 adult and 1 jack spring chinook (O. tshawytscha) enumerated at the Nursery Bridge Dam fishway adult trap between January 1 and June 23, 2003. Summer steelhead and spring chinook were observed moving upstream while bull trout were observed moving both upstream and downstream of the facility. Operation of the Little Walla Walla River juvenile trap for trap and haul purposes was not necessary this year. The project transported 21 adult spring chinook from Ringold Springs Hatchery and 281 from Threemile Dam to the South Fork Walla Walla Brood Holding Facility. Of these, 290 were outplanted in August for natural spawning in the basin.

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

2004-03-01

214

A magnetically isolated cuprate spin-ladder system: synthesis, structures, and magnetic properties.  

Science.gov (United States)

We synthesized and characterized two magnetically isolated spin ladders, Cu2(CO3)(ClO4)2(NH3)6 (1) and Cu2(CO3)(ClO4)2(H2O)(NH3)5 (2), which are the first examples of carbonate bridging molecular spin ladders. Compounds 1 and 2 form a ladder configuration by stacking a structural unit composed of two Cu(2+) ions and one CO3(2-), where the Cu-O-Cu interactions form the rungs and legs of each ladder and the counter anions (ClO4(-)) occupy the space between the ladders and ensure their magnetic isolation. A S = 1/2 magnetically isolated spin-ladder model with a ladder-rung magnetic interaction J1/k(B) = 364 K (where J is defined as positive for antiferromagnetic interactions) and a ladder-leg magnetic interaction J2/k(B) = 27.4 K accurately predicts the temperature dependence of the molar magnetic susceptibility for 1. The ladder configuration of 2 is similar to that of 1 except that the CO3(2-) is alternately skewed in different directions in the stacked structural unit. Interestingly, this minor structural variation in 2 results in its remarkably different magnetic behavior; the magnetic susceptibility curve of 2 is accurately described by an alternating chain model with J3/k(B) = 7.26 K and J4/k(B) = 4.42 K. PMID:25030616

Zhang, Xiao; Nishihara, Sadafumi; Nakano, Yuki; Yoshida, Erina; Kato, Chisato; Ren, Xiao-Ming; Maryunina, Kseniya Yu; Inoue, Katsuya

2014-09-14

215

Majorana fermions qubit states and non-Abelian braiding statistics in quenched inhomogeneous spin ladders  

Science.gov (United States)

In studying Majorana fermions (MFs) in a spin ladder model, we numerically show that their qubit state can be read out by measuring fusion excitations in quenched inhomogeneous spin ladders. We construct an exactly solvable T-junction spin ladder model that can be used to implement MF braid operations. With braiding simulated numerically as nonequilibrium quench processes, we verify that the MFs in our spin ladder model obey non-Abelian braiding statistics. Our scheme provides a promising platform to study exotic properties of MFs and a broad range of applications in topological quantum computation.

He, Yin-Chen; Chen, Yan

2013-11-01

216

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-07-01

217

Fish Mouths  

Science.gov (United States)

This activity (page 2 of the PDF) is a full inquiry investigation into environmental adaptation. Groups of learners will observe fish at a zoo, aquarium, or fish store and categorize which way the mouth of each identified fish faces. Based on observations made while the fish are fed and additional research, conclusions should be developed about how the fish fits into its environment. This activity can be used to teach learners about the importance of writing good notes while making observations. Relates to linked video, DragonflyTV GPS: California Fish.

Twin Cities Public Television, Inc.

2006-01-01

218

Absence of extended states in a ladder model of DNA  

CERN Document Server

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

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

2006-01-01

219

Two-loop ladder diagram contributions to Bhabha scattering. III  

International Nuclear Information System (INIS)

The authors evaluate, in the high-energy limit, the sum of the Feynman amplitudes corresponding the six two-loop ladder-like diagrams in Bhabha scattering. This is the limit where s??, while t, the electron mass m and the photon mass ? are all being held fixed. In this limit the sum of the six Feynman amplitudes does not depend on the electron mass. When specialized to the region s>>t>>m2>>?2, this result complements the one previously obtained. The connection with ?3 theory is also investigated. 6 refs

220

Period halving of Persistent Currents in Mesoscopic Mobius ladders  

CERN Document Server

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

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

2002-01-01

221

Beyond rainbow-ladder in bound state equations  

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-05-15

222

Optical coherences and wavelength mismatch in ladder systems  

CERN Document Server

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

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

2013-01-01

223

The phonon and thermal properties of a ladder nanostructure  

Directory of Open Access Journals (Sweden)

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

M Mardaani

2011-12-01

224

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

225

Climbing the Jaynes-Cummings ladder by photon counting  

CERN Document Server

We present a new method to observe direct experimental evidence of Jaynes--Cummings nonlinearities in a strongly dissipative cavity quantum electrodynamics system, where large losses compete with the strong light-matter interaction. This is a highly topical problem, particularly for quantum dots in microcavities where transitions from higher rungs of the Jaynes--Cummings ladder remain to be evidenced explicitly. We compare coherent and incoherent excitations of the system and find that resonant excitation of the detuned emitter make it possible to unambiguously evidence few photon quantum nonlinearities in currently available experimental systems.

Laussy, Fabrice P; Schrapp, Michael; Laucht, Arne; Finley, Jonathan J

2011-01-01

226

Diquark bound states at far beyond ladder truncation  

CERN Document Server

The Bethe-Salpeter equation in the diquark channel is investigated by employing the Dyson-Schwinger method together with the Munczek-Nemirovsky model. The novelty of our study is a resummation of completely-crossed ladder diagrams in the Bethe-Salpeter kernel. These diagrams are enhanced due to their color factors in the diquark channel, but not in the meson channel. As a result of our analysis, it is suggested that diquark bound-state solutions exist in the Bethe-Salpeter equation, which have been thought to be absent.

Jinno, Ryusuke; Mishima, Go

2015-01-01

227

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

228

Low-frequency current fluctuations in doped ladders  

CERN Document Server

Charge current static and dynamical correlations are computed by exact diagonalisation methods on a 2-leg t-t'-J ladder which exhibits a sharp transition between a Luther-Emery (LE) phase of hole pairs and a phase with deconfined holes. In the LE phase, we find short-range low-energy incommensurate current fluctuations which are intrinsically connected to the internal charge dynamics within one hole pair. On the contrary, when holes unbind, the maximum of the current susceptibility moves abruptly to the commensurate wavevector $\\pi$ and strongly increases for decreasing doping suggesting an instability towards a staggered flux state at sufficiently small doping.

Tsutsui, K; Capponi, S; Tsutsui, Kenji; Poilblanc, Didier; Capponi, Sylvain

2001-01-01

229

Third-order differential ladder operators and supersymmetric quantum mechanics  

Energy Technology Data Exchange (ETDEWEB)

Hierarchies of one-dimensional Hamiltonians in quantum mechanics admitting third-order differential ladder operators are studied. Each Hamiltonian has associated three-step Darboux (pseudo)-cycles and Painleve IV equations as a closure condition. The whole hierarchy is generated applying some operations on the cycles. These operations are investigated in the frame of supersymmetric quantum mechanics and mainly involve algebraic manipulations. A consistent geometric representation for the hierarchy and cycles is built that also helps in understanding the operations. Three kinds of hierarchies are distinguished and a realization based on the harmonic oscillator Hamiltonian is supplied, giving an interpretation for the spectral properties of the Hamiltonians of each hierarchy.

Mateo, J; Negro, J [Departamento de Fisica Teorica, Atomica y Optica, Facultad de Ciencias, E-47011 Valladolid (Spain)

2008-02-01

230

Third-order differential ladder operators and supersymmetric quantum mechanics  

International Nuclear Information System (INIS)

Hierarchies of one-dimensional Hamiltonians in quantum mechanics admitting third-order differential ladder operators are studied. Each Hamiltonian has associated three-step Darboux (pseudo)-cycles and Painleve IV equations as a closure condition. The whole hierarchy is generated applying some operations on the cycles. These operations are investigated in the frame of supersymmetric quantum mechanics and mainly involve algebraic manipulations. A consistent geometric representation for the hierarchy and cycles is built that also helps in understanding the operations. Three kinds of hierarchies are distinguished and a realization based on the harmonic oscillator Hamiltonian is supplied, giving an interpretation for the spectral properties of the Hamiltonians of each hierarchy

231

Numerical Studies of the two-leg Hubbard ladder  

OpenAIRE

The Hubbard model on a two-leg ladder structure has been studied by a combination of series expansions at T=0 and the density-matrix renormalization group. We report results for the ground state energy $E_0$ and spin-gap $\\Delta_s$ at half-filling, as well as dispersion curves for one and two-hole excitations. For small $U$ both $E_0$ and $\\Delta_s$ show a dramatic drop near $t/t_{\\perp}\\sim 0.5$, which becomes more gradual for larger $U$. This represents a crossover from a ...

Weihong, Zheng; Oitmaa, J.; Hamer, C. J.; Bursill, R. J.

2000-01-01

232

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.

233

Role of Structural Asymmetry in Controlling Drop Spacing in Microfluidic Ladder Networks  

Science.gov (United States)

Manipulation of drop spacing is crucial to many processes in microfluidic devices including drop coalescence, detection and storage. Microfluidic ladder networks ---where two droplet-carrying parallel channels are connected by narrow bypass channels through which the motion of drops is forbidden---have been proposed as a means to control relative separation between pairs of drops. Prior studies in microfluidic ladder networks with vertical bypasses, which possess fore-aft structural symmetry, have revealed that pairs of drops can only undergo reduction in drop spacing at the ladder exit. We investigate the dynamics of drops in microfluidic ladder networks with both vertical and slanted bypasses. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative spacing between drops, enabling them to contract, synchronize, expand or even flip at the ladder exit. Our experiments confirm all the behaviors predicted by theory. Numerical analysis further shows that ladders containing several identical bypasses can only linearly transform the input drop spacing. Finally, we find that ladders with specific combinations of vertical and slanted bypasses can generate non-linear transformation of input drop spacing, despite the absence of drop decision-making events at the bypass junctions.

Wang, William; Maddala, Jeevan; Vanapalli, Siva; Rengasamy, Raghunathan

2012-02-01

234

An Evaluation of the Career Ladder Compensation Plan: Peoria Unified School District, Peoria, Arizona.  

Science.gov (United States)

This report provides the Career Ladder Committee of Peoria Unified School District, Peoria, Arizona with an evaluation of the school district's Career Ladder Compensation Plan (CLCP). The Far West Laboratory for Educational Research and Development, in February, 1989, was contracted to assess the impact of the CLCP on teacher work and school…

Nelson, Linda J.; And Others

235

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 ...

236

Assembly procedure for the silicon pixel ladder for PHENIX silicon vertex tracker  

International Nuclear Information System (INIS)

The silicon vertex tracker (VTX) will be installed in the summer of 2010 to enhance the physics capabilities of the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) experiment at Brookhaven National Laboratory. The VTX consists of two types of silicon detectors: a pixel detector and a strip detector. The pixel detector consists of 30 pixel ladders placed on the two inner cylindrical layers of the VTX. The ladders are required to be assembled with high precision, however, they should be assembled in both cost and time efficient manner. We have developed an assembly bench for the ladder with several assembly fixtures and a quality assurance (Q/A) system using a 3D measurement machine. We have also developed an assembly procedure for the ladder, including a method for dispensing adhesive uniformly and encapsulation of bonding wires. The developed procedures were adopted in the assembly of the first pixel ladder and satisfy the requirements.

237

Assembly procedure for the silicon pixel ladder for PHENIX silicon vertex tracker  

Energy Technology Data Exchange (ETDEWEB)

The silicon vertex tracker (VTX) will be installed in the summer of 2010 to enhance the physics capabilities of the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) experiment at Brookhaven National Laboratory. The VTX consists of two types of silicon detectors: a pixel detector and a strip detector. The pixel detector consists of 30 pixel ladders placed on the two inner cylindrical layers of the VTX. The ladders are required to be assembled with high precision, however, they should be assembled in both cost and time efficient manner. We have developed an assembly bench for the ladder with several assembly fixtures and a quality assurance (Q/A) system using a 3D measurement machine. We have also developed an assembly procedure for the ladder, including a method for dispensing adhesive uniformly and encapsulation of bonding wires. The developed procedures were adopted in the assembly of the first pixel ladder and satisfy the requirements.

Onuki, Y. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)], E-mail: onuki@awa.tohoku.ac.jp; Akiba, Y. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); En' yo, H.; Fujiwara, K. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Haki, Y.; Hashimoto, K. [Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501 (Japan); Ichimiya, R. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kasai, M.; Kawashima, M.; Kurita, K. [Physics Department, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501 (Japan); Kurosawa, M. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Mannel, E.J. [Columbia University, New York, NY 10027 (United States); Nevis Laboratories, Irvington, NY 10533 (United States); Nakano, K. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Pak, R. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Sekimoto, M. [KEK, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Sondheim, W.E. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Taketani, A. [RIKEN Nishina Center for Accelerator Based Science, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Togawa, M. [RIKEN BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Yamamoto, Y. [Department of Mechanical Engineering and Intelligent Systems, University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo (Japan)

2009-07-21

238

Assembly procedure for the silicon pixel ladder for PHENIX silicon vertex tracker.  

Energy Technology Data Exchange (ETDEWEB)

The silicon vertex tracker (VTX) will be installed in the summer of 2010 to enhance the physics capabilities of the Pioneering High Energy Nuclear Interaction eXperiment (PHENIX) experiment at Brookhaven National Laboratory. The VTX consists of two types of silicon detectors: a pixel detector and a strip detector. The pixel detector consists of 30 pixel ladders placed on the two inner cylindrical layers of the VTX. The ladders are required to be assembled with high precision, however, they should be assembled in both cost and time efficient manner. We have developed an assembly bench for the ladder with several assembly fixtures and a quality assurance (Q/A) system using a 3D measurement machine. We have also developed an assembly procedure for the ladder, including a method for dispensing adhesive uniformly and encapsulation of bonding wires. The developed procedures were adopted in the assembly of the first pixel ladder and satisfy the requirements.

Onuki, Y.; PHENIX Collaboration, et al.

2009-05-08

239

On the energy spectrum of t-J model on the distorted necklace ladder  

International Nuclear Information System (INIS)

The effective low-energy Hamiltonians for t-J model on distorted necklace ladder formed by weakly interacting unit cells are derived by means of perturbation theory and cyclic spin permutation formalism. It is shown that in contrast of similar rectangular ladder model there are no magnetic polarons in necklace ladder model. For finite necklace ladder fragments with L unit cells and N = 3L-1 electrons nonmonotonic dependence of the ground state spin S0 as function of exchange parameter J is shown numerically. In particular, for cyclic fragment formed by 4 unit cells, at 0 0 to minimal value, and then new increase up to the value S0 = 3/2, which in agreement with our qualitative estimation S0 = (L -1)/2 for big values of J. The exact separation of charge and spin variables for cyclic necklace-ladder fragments for even L and 3L - 1 electrons in correspondent t-J model is shown.

240

Absolutely continuous energy bands in the electronic spectrum of quasiperiodic ladder networks  

Science.gov (United States)

The energy spectra of quasi-one-dimensional quasiperiodic ladder networks are analyzed within a tight binding description. In particular, we show that if a selected set of sites in each strand of a ladder is tunnel-coupled to quantum dots attached from a side, absolutely continuous subbands can be generated in the spectrum if one tunes the dot potential and the dot-strand coupling appropriately. Typical cases with two and three strand Fibonacci ladders in the off-diagonal model are discussed in details. We also discuss the possibility of re-entrant insulator-metal transition for a general n-strand ladder network when n becomes large. The observations remain valid even in the case of a disordered ladder network with the same constituents. The results are analytically exact.

Pal, Biplab; Chakrabarti, Arunava

2014-06-01

241

The tunable quantum spin ladder Cu(Qnx)(Cl(1-x)Brx)2  

Science.gov (United States)

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.

Povarov, K. Yu.; Lorenz, W. E. A.; Xiao, F.; Landee, C. P.; Krasnikova, Y.; Zheludev, A.

2014-12-01

242

49 CFR 214.519 - Floors, decks, stairs, and ladders of on-track roadway maintenance machines.  

Science.gov (United States)

...2010-10-01 2010-10-01 false Floors, decks, stairs, and ladders of on-track...and Hi-Rail Vehicles § 214.519 Floors, decks, stairs, and ladders of on-track roadway maintenance machines. Floors, decks, stairs, and ladders of...

2010-10-01

243

The Doped t-J Ladder via series expansions  

International Nuclear Information System (INIS)

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

244

Fish immunostimulants  

OpenAIRE

Fish immunostimulants are important substances useful to control infectious fish diseases and aresubstantially beneficial to the aquaculture business and environment.This literature review covers the results of using fish immune modulators, including bacteria and bacterial derivatives, adjuvants, chitin, glucan, vitamin, and other synthetic materials. These immunostimulants enhance the activities of phagocytotic cells, stimulate the immunological cells to create more lysozymes and more antibo...

Chitmanat, C.

2002-01-01

245

Fish Prints  

Science.gov (United States)

In this hands-on art activity, learners will study and identify features of the external anatomy of a fish. They will have the opportunity to learn the different functions of fish anatomy along with new vocabulary terms while handling a real fish in their art project. Also, a discussion may take place about the different kinds of fish and how different shapes are more beneficial for certain environments. As a wrap up, learners can become familiar about issues related to the conservation of fish, such as overfishing, habitat destruction, and invasive species. This activity is standards-based.

Sciences, California A.

2008-01-01

246

36 CFR 2.3 - Fishing.  

Science.gov (United States)

...INTERIOR RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.3 Fishing...statutory law. (5) Fishing by the use of drugs, poisons, explosives, or electricity...raft or float designated for water sports, or within the limits of...

2010-07-01

247

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

248

Transport Properties of Doped t-J Ladders  

CERN Document Server

Conductivity and Hall coefficient for various types of t-J ladders are calculated as a function of temperature and frequency by numerical diagonalization. A crossover from an incoherent to a coherent charge dynamics is found at a temperature T_{coh}. There exists another crossover at T_{PG} below which a pseudogap opens in the optical spectra, induced by the opening of a spin gap. In the absence of the spin gap, T_{coh} and the coherent weight are suppressed especially with increasing dimensionality. On the contrary, T_{coh} is strongly enhanced by the pseudogap formation below T_{PG}, where the coherent Drude weight decreases with increasing dimensionality. The Hall coefficient shows a strong crossover at T_{PG} below which it has large amplitude for small doping concentration.

Tsunetsugu, H; Tsunetsugu, Hirokazu; Imada, Masatoshi

1997-01-01

249

Phase sensitive quantum interference on forbidden transition in ladder scheme  

CERN Document Server

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

Koganov, Gennady A

2014-01-01

250

Topological phases of the two-leg Kitaev ladder  

International Nuclear Information System (INIS)

We study the phase diagram of the two-leg Kitaev model. Different topological phases can be characterized by either the number of Majorana modes for a deformed chain of the open ladder, or by a winding number related to the ‘h-loop’ in the momentum space. By adding a three-spin interaction term to break the time-reversal symmetry, two originally different phases are glued together, so that the number of Majorana modes reduce to 0 or 1, namely, the topological invariant collapses to Z2 from an integer Z. These observations are consistent with a recent general study [S. Tewari, J.D. Sau, (arXiv:1111.6592v2)].

251

Quantum Walks of SU(2)_k Anyons on a Ladder  

CERN Document Server

We study the effects of braiding interactions on single anyon dynamics using a quantum walk model on a quasi-1-dimensional ladder filled with stationary anyons. The model includes loss of information of the coin and nonlocal fusion degrees of freedom on every second time step, such that the entanglement between the position states and the exponentially growing auxiliary degrees of freedom is lost. The computational complexity of numerical calculations reduces drastically from the fully coherent anyonic quantum walk model, allowing for relatively long simulations for anyons which are spin-1/2 irreps of SU(2)_k Chern-Simons theory. We find that for Abelian anyons, the walk retains the ballistic spreading velocity just like particles with trivial braiding statistics. For non-Abelian anyons, the numerical results indicate that the spreading velocity is linearly dependent on the number of time steps. By approximating the Kraus generators of the time evolution map by circulant matrices, it is shown that the spatial...

Lehman, L; Brennen, G K

2012-01-01

252

Nuclear Spin Relaxation in Hole Doped Two-Leg Ladders  

CERN Document Server

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.

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

2000-01-01

253

Consumers' perceptions of African wildlife meat : A laddering study  

DEFF Research Database (Denmark)

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

Radder, Laetitia; Grunert, Klaus G.

2009-01-01

254

Numerical Studies of the two-leg Hubbard ladder  

CERN Document Server

The Hubbard model on a two-leg ladder structure has been studied by a combination of series expansions at T=0 and the density-matrix renormalization group. We report results for the ground state energy $E_0$ and spin-gap $\\Delta_s$ at half-filling, as well as dispersion curves for one and two-hole excitations. For small $U$ both $E_0$ and $\\Delta_s$ show a dramatic drop near $t/t_{\\perp}\\sim 0.5$, which becomes more gradual for larger $U$. This represents a crossover from a "band insulator" phase to a strongly correlated spin liquid. The lowest-lying two-hole state rapidly becomes strongly bound as $t/t_{\\perp}$ increases, indicating the possibility that phase separation may occur. The various features are collected in a "phase diagram" for the model.

Weihong, Z; Hamer, C J; Bursill, R J; Weihong, Zheng

2001-01-01

255

242-A/LERF programmable Logic Controller Ladder. Revision 1  

Energy Technology Data Exchange (ETDEWEB)

This document defines and describes the user-generated application software written to transmit digital and analog signals from the Liquid Effluent Retention Facility (LERF) to the 242-A Evaporator Distributed Control System (DCS). PLCs and modems were installed in the 242-A Evaporator by Project W-105 (LERF) to transmit 6 analog liquid level signals, 6 range alarms based on the analog signals, and 6 leak detection and pump status signals to the 242-A Distributive Control System (DCS) from LERF. Communications between the two facilities are also monitored and alarm on the DCS. Following the Project W-105 completion, the communications and signal mix were modified by Project C-018H (ETF). The current PLC software (including ladder logic and data tables), PLC hardware settings, and modern option settings to transmit the signals and monitor communications are documented and described in this document.

Teats, M.C.

1995-05-23

256

Inelastic neutron scattering from the spin ladder compound (VO)2P2O7  

CERN Document Server

We present results from an inelastic neutron scattering experiment on the candidate Heisenberg spin ladder vanadyl pyrophosphate, (VO)2P2O7. We find evidence for a spin-wave excitation gap of E_{gap} = 3.7\\pm 0.2 meV, at a band minimum near Q=0.8 A^{-1}. This is consistent with expectations for triplet spin waves in (VO)2P2O7 in the spin-ladder model, and is to our knowledge the first confirmation in nature of a Heisenberg antiferromagnetic spin ladder.

Eccleston, R S; Brody, J P; Johnson, J W

1994-01-01

257

An infinite family of superintegrable systems from higher order ladder operators and supersymmetry  

International Nuclear Information System (INIS)

We discuss how we can obtain new quantum superintegrable Hamiltonians allowing the separation of variables in Cartesian coordinates with higher order integrals of motion from ladder operators. We also discuss how higher order supersymmetric quantum mechanics can be used to obtain systems with higher order ladder operators and their polynomial Heisenberg algebra. We present a new family of superintegrable systems involving the fifth Painleve transcendent which possess fourth order ladder operators constructed from second order supersymmetric quantum mechanics. We present the polynomial algebra of this family of superintegrable systems.

258

An infinite family of superintegrable systems from higher order ladder operators and supersymmetry  

Energy Technology Data Exchange (ETDEWEB)

We discuss how we can obtain new quantum superintegrable Hamiltonians allowing the separation of variables in Cartesian coordinates with higher order integrals of motion from ladder operators. We also discuss how higher order supersymmetric quantum mechanics can be used to obtain systems with higher order ladder operators and their polynomial Heisenberg algebra. We present a new family of superintegrable systems involving the fifth Painleve transcendent which possess fourth order ladder operators constructed from second order supersymmetric quantum mechanics. We present the polynomial algebra of this family of superintegrable systems.

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

2011-03-01

259

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

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...

Barclay, Paula

2013-01-01

260

Fish Skull Animation: Jaw Protrusion  

Science.gov (United States)

This collection of fish-skull animations is from Diversity of Fishes, part of the Museum's Seminars on Science series. These distance-learning courses are designed to help educators meet the new national science standards. The three QuickTime movies take a look at the various aspects of jaw protrusion.

261

29 CFR 1910.29 - Manually propelled mobile ladder stands and scaffolds (towers).  

Science.gov (United States)

...AND HEALTH STANDARDS Walking-Working Surfaces § 1910.29 Manually propelled mobile...dismantled lumber.) (v) All exposed surfaces shall be free from sharp edges, burrs...ladder stands shall be fabricated from slip resistant treads. (v) The...

2010-07-01

262

Incommensurate nodes in the energy spectrum of weakly coupled antiferromagnetic Heisenberg ladders  

CERN Document Server

Heisenberg ladders are investigated using the bond-mean-field theory [M.Azzouz, Phys. Rev. B 48, 6136 (1993)]. The zero inter-ladder coupling energy gap, the uniform spin susceptibility and the nuclear magnetic resonance spin-relaxation rate are calculated as a function of temperature and magnetic field. For weakly coupled ladders, the energy spectrum vanishes at incommensurate wavevectors giving rise to nodes. As a consequence, the spin susceptibility becomes linear at low temperature. Our results for the single ladder successfully compare to experiments on SrCu_2O_3 and (VO)_2P_2O_7 materials and new predictions concerning the coupling to the magnetic field are made.

Azzouz, M; Benyoussef, A

1997-01-01

263

Ab initio study of ladder-type polymers polythiophene and polypyrrole  

CERN Document Server

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

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

2006-01-01

264

Venomous Fish  

Science.gov (United States)

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

Productions, Jonathan B.

2010-08-10

265

Texture Fish  

Science.gov (United States)

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,…

Stone, Julie

2007-01-01

266

Cooperative self-assembly of double-strand conjugated porphyrin ladders  

OpenAIRE

A series of conjugated zinc porphyrin oligomers, from the dimer through to the hexamer, form stable ladder complexes with linear bidentate ligands such as 1,4-diazabicyclo[2.2.2]octane (DABCO) and 4,4'-bipyridyl (Bipy). The 1H NMR spectra of these ladders confirm their structures and show how they fray and dissociate in the presence of excess ligand. The thermodynamics of these equilibria were elucidated by spectrophotometric titration, using multivariate global fa...

Taylor, Pn; Anderson, Hl

1999-01-01

267

Effect of temperature on quantum criticality in the frustrated two-leg Heisenberg ladder  

OpenAIRE

The antiferromagnetic Heisenberg model on the two-leg ladder with exchange interactions along the chains, rungs, and diagonals is studied using the Jordan-Wigner transformation and bond-mean-field theory. The inclusion of all three couplings introduces frustration to the system and depending on their relative strengths the ladder can adopt one of three possible magnetically-disordered gapped states. The phase diagram found in this mean-field approach is in very good agreemen...

Ramakko, Brandon W.; Azzouz, Mohamed

2007-01-01

268

Quantum phase transitions in the exactly solved spin-1/2 Heisenberg-Ising ladder  

OpenAIRE

Ground-state behaviour of the frustrated quantum spin-1/2 two-leg ladder with the Heisenberg intra-rung and Ising inter-rung interactions is examined in detail. The investigated model is transformed to the quantum Ising chain with composite spins in an effective transverse and longitudinal field by employing either the bond-state representation or the unitary transformation. It is shown that the ground state of the Heisenberg-Ising ladder can be descended from three exactly ...

Verkholyak, Taras; Strecka, Jozef

2012-01-01

269

Studies of Quantum Spin Ladders at T=0 and at High Temperatures by Series Expansions  

OpenAIRE

We have carried out extensive series studies, at T=0 and at high temperatures, of 2-chain and 3-chain spin-half ladder systems with antiferromagnetic intrachain and both antiferromagnetic and ferromagnetic interchain couplings. Our results confirm the existence of a gap in the 2-chain Heisenberg ladders for all non-zero values of the interchain couplings. Complete dispersion relations for the spin-wave excitations are computed. For 3-chain systems, our results are consistent...

Oitmaa, J.; Singh, Rajiv R. P.; Weihong, Zheng

1996-01-01

270

Do Fish Enhance Tank Mixing?  

DEFF Research Database (Denmark)

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

Rasmussen, Michael R.; Laursen, Jesper

2005-01-01

271

Multiple Robotic Fish’s Target Search and Cooperative Hunting Strategies  

Directory of Open Access Journals (Sweden)

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

Da Lin

2013-07-01

272

50 CFR 223.203 - Anadromous fish.  

Science.gov (United States)

...from NMFS Northwest Region's website (www.nwr.noaa.gov ...a description of the study design, including a justification...approve a juvenile fish screen design and construction plan and...deviates from the approved design, the water diversion...

2010-10-01

273

Archaeological Fish Bones Online: a digital archive of Sydney fishes  

Directory of Open Access Journals (Sweden)

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.

Sarah Colley

2010-12-01

274

Static Holes in Geometrically Frustrated Bow Tie Ladder  

Science.gov (United States)

Doping of the geometrically frustrated bow-tie spin ladder with static holes is investigated by a complementary approach using exact diagonalization and hard-core quantum dimers. Results for the thermodynamics in the undoped case, the singlet density of states, the hole-binding energy, and the spin correlations will be presented. We find that the static holes polarize their vicinity by a localization of singlets in order to reduce the frustration. As a consequence the singlet polarization cloud induces short range repulsive forces between the holes with oscillatory longer range behavior. For those systems we have studied, most results for the quantum dimer approach are found to be qualitatively if not quantitatively in agreement with exact diagonalization. The ground state of the undoped system is non-degenerate with translationally invariant nearest-neighbor spin correlations up to a few unit cells, which is consistent with a spin liquid state or a valence bond crystal with very large unit cell. C. Waldtmann, A. Kreutzmann, U. Schollwock, K. Maisinger, and H.-U. Everts, Phys. Rev. B 62, 9472 (2000).

Martins, George; Brenig, Wolfram

2007-03-01

275

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

Science.gov (United States)

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

Wei, Hui-Ling; Liu, Yu-Fang

2014-09-01

276

One Fish, Two Fish, Redfish, You Fish!  

Science.gov (United States)

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…

White, Katherine; Timmons, Maryellen; Medders, Paul

2011-01-01

277

Quantum entanglement and thermal reduced density matrices in fermion and spin systems on ladders  

International Nuclear Information System (INIS)

Numerical studies of the reduced density matrix of a gapped spin-1/2 Heisenberg antiferromagnet on a two-leg ladder find that it has the same form as the Gibbs density matrix of a gapless spin-1/2 Heisenberg antiferromagnetic chain at a finite temperature determined by the spin gap of the ladder. We investigate this interesting result by considering a model of free fermions on a two-leg ladder (gapped by the inter-chain tunneling operator) and in spin systems on a ladder with a gapped ground state using exact solutions and several controlled approximations. We calculate the reduced density matrix and the entanglement entropy for a leg of the ladder (i.e. a cut made between the chains). In the fermionic system we find the exact form of the reduced density matrix for one of the chains and determine the entanglement spectrum explicitly. Here we find that in the weak tunneling limit of the ladder the entanglement entropy of one chain of the gapped ladder has a simple and universal form dictated by conformal invariance. In the case of the spin system, we consider the strong coupling limit by using perturbation theory and get the reduced density matrix by the Schmidt decomposition. The entanglement entropies of a general gapped system of two coupled conformal field theories (in 1 + 1 dimensions) are discussed using the replica trick and scaling arguments. We show that (1) for a system with a bulk gap the reduced density matrix has the form of a thermal density matrix, (2) the long-wavelength modes of one subsystem (a chain) of a gapped coupled system are always thermal, (3) the von Neumann entropy equals the thermodynamic entropy of one chain, and (4) the bulk gap plays the role of effective temperature. (paper)

278

About Fish  

Science.gov (United States)

This activity introduces students to an animal that is to be the subject of much experimentation by them. Because most fish have a relatively simple form and exhibit a wide variety of colors and patterns, they prove to be an excellent animal for experimental study of many aspects of coloration. The body of the lesson is devoted to a description and discussion of the external structure of fish.

Ipsen, David; Gillfillan, Gretchen L.; Judy Diamond (Revised New Edition); Judy Scotchmoor (Revised New Edition); Stebbins, Robert

2008-04-01

279

Hood River Pelton Ladder Studies : Annual Report 1995.  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1996-09-01

280

DISPOSAL OF SMALL-SCALE FISH PROCESSING WASTE THROUGH COMPOSTING  

Science.gov (United States)

Large catfish processors in the U.S. typically recycle fish waste into fish meal. For small-scale processors or aquaculture research facilities, fish waste disposal can be problematic. We adapted a design developed for composting wastes from Minnesota fishing lodges and tested it for suitability fo...

281

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.

282

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

Energy Technology Data Exchange (ETDEWEB)

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

Roux, G

2007-07-15

283

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

DEFF Research Database (Denmark)

Executive summary 1. Means-end chains are a device used to understand how consumers mentally link products to self-relevant consequences. Means-end chains are usually measured by a method called laddering. 2. Means-end chains may fall short of tapping all relevant aspects of how consumers think about products. Specifically, nonverbal imagery, episodic information, and procedural knowledge are not included in means-end chains. 3. A number of methodological problems can be identified in the collection of means-end chain data. Major problems, which should be addressed in research, are methods to elicit the product attributes the laddering is to start with, the integration of a usage situation in the interview, and the basic decision on how much direct the respondent. 4. Concerning the coding of laddering data, a higher degree of transparency of the coding process would be desirable. 5. Hierarchical value maps, a major graphic device used to visualise results from laddering studies, should take care of possible non-homogeneity of respondents and of the intricacies of aggregation following from it. 6. A catalog of research topics is developed that can guide studies aimed at improving the means-end chains and laddering methodology.

Grunert, Klaus G.; Grunert, Suzanne C.

1995-01-01

284

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

285

Critical properties of $S=1/2$ Heisenberg ladders in magnetic fields  

CERN Document Server

The critical properties of the $S=1/2$ Heisenberg two-leg ladders are investigated in a magnetic field. Combining the exact diagonalization method and the finite-size-scaling analysis based on conformal field theory, we calculate the critical exponents of spin correlation functions numerically. For a strong interchain coupling, magnetization dependence of the critical exponents shows characteristic behavior depending on the sign of the interchain coupling. We also calculate the critical exponents for the $S=1/2$ Heisenberg two-leg ladder with a diagonal interaction, which is thought as a model Hamiltonian of the organic spin ladder compound ${Cu}_2({1,4-diazacycloheptane})_2{Cl}_4$. Numerical results are compared with experimental results of temperature dependence of the NMR relaxation rate $1/T_1$.

Usami, M

1998-01-01

286

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

287

Climb the Green Ladder Make Your Company and Career More Sustainable  

CERN Document Server

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

Fetzer, Amy V

2009-01-01

288

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

289

Resonant Inelastic X-ray Scattering (RIXS) Spectra for Ladder Cuprates  

OpenAIRE

The ladder compound Sr$_{14}$Cu$_{24}$O$_{41}$ is of interest both as a quasi-one-dimensional analog of the superconducting cuprates and as a superconductor in its own right when Sr is substituted by Ca. In order to model resonant inelastic x-ray scattering (RIXS) spectra for this compound, we investigate the simpler SrCu$_{2}$O$_{3}$ system in which the crystal structure contains very similar ladder planes. We approximate the LDA dispersion of SrCu$_{2}$O$_{3}$ by a Cu only...

Al-sawai, W.; Markiewicz, R. S.; Hasan, M. Z.; Bansil, A.

2008-01-01

290

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

Science.gov (United States)

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

Phelan, Denis; O'Sullivan, Leonard

2014-11-01

291

Amplified optical nonlinearity in a self-assembled double-strand conjugated porphyrin polymer ladder.  

OpenAIRE

Addition of 4,4'-bipyridyl to a solution of a meso-meso butadiyne-linked conjugated zinc porphyrin polymer in chloroform results in self-assembly of a double-strand ladder complex. Excess ligand causes this duplex to dissociate into single strands. These binding processes were elucidated by near-IR and NMR titrations, as well as by gel permeation chromatography and small-angle neutron scattering. Ladder-making and -breaking are highly cooperative, with Hill coefficients of 3.0 and 3.7, respec...

Screen, Te; Thorne, Jr; Denning, Rg; Bucknall, Dg; Anderson, Hl

2002-01-01

292

Raman Response in Antiferromagnetic Two-Leg S=1/2 Heisenberg Ladders  

CERN Document Server

The Raman response in the antiferromagnetic 2-leg S=1/2 Heisenberg ladder is calculated for various couplings by continuous unitary transformations. For leg couplings above 80% of the rung coupling a characteristic 2-peak structure occurs with a point of zero intensity within the continuum. Experimental data for CaV_2O_5 and La_yCa_(14-y)Cu_24O_41 are analyzed and the coupling constants are determined. Evidence is found that the Heisenberg model is not sufficient to describe cuprate ladders. We argue that a cyclic exchange term is the appropriate extension.

Schmidt, K P; Uhrig, G S; Schmidt, Kai P.; Knetter, Christian

2001-01-01

293

Karuk Fishing.  

Science.gov (United States)

A booklet on traditional fishing practices of the Karuk Indians of northwestern California is presented in the formal, literary English speech of Norman Goodwin, a Karuk medicine man involved in preserving ancient tribal traditions. Empirical information and personal narratives are combined in descriptions of different kinds of nets, social rules…

Bennett, Ruth, Ed.; Goodwin, Norman

294

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

Scientific Electronic Library Online (English)

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

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

2005-07-01

295

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

296

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

297

Applications of the Sensor Fish Technology  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2007-08-28

298

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  

Science.gov (United States)

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.

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

2015-02-01

299

Avionics Instrument Systems Specialist Career Ladder: AFSCs 32531, 32551, 31571, and 32591. Occupational Survey Report.  

Science.gov (United States)

The Avionics Instrument Systems career ladder (AFSC 325X1) provides flight line and shop maintenance training on aircraft instrument systems, electromechancial instruments, components, and test equipment. Duties involve inspecting, removing, installing, repairing, operating, troubleshooting, overhauling, and modifying systems such as flight and…

Air Force Occupational Measurement Center, Lackland AFB, TX.

300

Exact spontaneous plaquette ground states for spin-3/2 ladder models  

CERN Document Server

We present rigorous results on the spontaneous formation of plaquette ground states in spin-3/2 ladder models with SU(4) and SO(5) symmetries. The elementary excitations are also investigated based on the exact solution for the ground state.

Chen, S; Zhang, S C; Wang, Y; Chen, Shu; Wu, Congjun; Zhang, Shou-Cheng; Wang, Yupeng

2005-01-01

301

Spin-lattice relaxation time in pressure-induced two-leg ladder cuprate superconductors  

International Nuclear Information System (INIS)

Spin-lattice relaxation time in pressure-induced two-leg ladder cuprate superconductors is investigated based on the kinetic energy driven superconducting mechanism. It is shown that the spin-lattice relaxation time exhibits a temperature linear dependence at low temperature followed by a peak developed below the superconducting transition temperature, in qualitative agreement with experiments.

302

A twisted ladder: relating the Fe superconductors to the high-Tc cuprates  

International Nuclear Information System (INIS)

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

303

Carbon isotope enrichment by retention of isotopic excitation selectivity in VV ladder climbing collisions  

International Nuclear Information System (INIS)

Initial isotopic excitation selectivity in cw CO2 laser pumping of 12CH3F and 13CH3F is retained in upper vibrational states even after ladder climbing collisions. Reaction of these states with atomic bromine samples this non-equilibrium distribution and produces isotopically enriched product, CH2FBr, with projected excellent energy efficiency. (orig.)

304

Astronaut Edwin Aldrin descends steps of Lunar Module ladder to walk on moon  

Science.gov (United States)

Astronaut Edwin E. Aldrin Jr., lunar module pilot, descends the steps of the Lunar Module (LM) ladder as he prepares to walk on the Moon. He had just egressed the LM. This picture was taken by Astronaut Neil A. Armstrong, commander, with a 70mm lunar surface camera.

1969-01-01

305

Studies of a 2-Chain Spin Ladder with Frustrating Second Neighbor Interactions  

CERN Document Server

The Heisenberg model on a 2-chain spin-1/2 ladder with frustrating second neighbor interactions is studied by using series expansions about the Ising and dimer limits, numerical diagonalization, and by Abelian bosonization analysis. The phase diagram is determined, and pair correlations and the complete dispersion relations for the triplet spin-wave excitations are also computed.

Weihong, Z; Oitmaa, J; Weihong, Zheng

1998-01-01

306

Studies of quantum spin ladders at T = 0 and at high temperatures  

Energy Technology Data Exchange (ETDEWEB)

Compounds have recently been found which, to a first approximation, can be regarded as `spin ladders`, i.e. 2 or 3 coupled chains of S = 2 ions. These are (VO){sub 2}P{sub 2}O{sub 7} and SrCu{sub 2}O{sub 3} (2 chains), and SrCu{sub 3}O{sub 5} (3 chains). A number of striking theoretical predictions have been made for such systems. Ladders with an even number of legs have an energy gap, short range correlations and a `spin liquid` ground state. Ladders with an odd number of legs, on the other hand, have gapless excitations and quasi long range order. Experiments appear to confirm these features, which are analogous to the Haldane gap in integer chains. We have carried out extensive series studies of 2-chain and 3-chain ladder systems, both at T = 0 and at high temperatures. Our results confirm the existence of a gap in the 2-chain system and identify the structure of the phase diagram. The dispersion law for excitations is estimated. For the 3-chain system we are unable to exclude the possibility of a small gap, although our results are quite consistent with a gapless spectrum. We estimate the high temperature magnetic susceptibility and compare with previous calculations and with experiment

Weihong, Z.; Oitmaa, J. [The University of New South Wales, Sydney, NSW (Australia). School of Physics; Singh, R.R.P. [University of California, Davis, CA (United States). Department of Physics

1996-12-31

307

Studies of a 2-Chain Spin Ladder with Frustrating Second Neighbor Interactions  

OpenAIRE

The Heisenberg model on a 2-chain spin-1/2 ladder with frustrating second neighbor interactions is studied by using series expansions about the Ising and dimer limits, numerical diagonalization, and by Abelian bosonization analysis. The phase diagram is determined, and pair correlations and the complete dispersion relations for the triplet spin-wave excitations are also computed.

Weihong, Zheng; Kotov, V.; Oitmaa, J.

1997-01-01

308

Studies of quantum spin ladders at T = 0 and at high temperatures  

International Nuclear Information System (INIS)

Compounds have recently been found which, to a first approximation, can be regarded as 'spin ladders', i.e. 2 or 3 coupled chains of S = 2 ions. These are (VO)2P2O7 and SrCu2O3 (2 chains), and SrCu3O5 (3 chains). A number of striking theoretical predictions have been made for such systems. Ladders with an even number of legs have an energy gap, short range correlations and a 'spin liquid' ground state. Ladders with an odd number of legs, on the other hand, have gapless excitations and quasi long range order. Experiments appear to confirm these features, which are analogous to the Haldane gap in integer chains. We have carried out extensive series studies of 2-chain and 3-chain ladder systems, both at T = 0 and at high temperatures. Our results confirm the existence of a gap in the 2-chain system and identify the structure of the phase diagram. The dispersion law for excitations is estimated. For the 3-chain system we are unable to exclude the possibility of a small gap, although our results are quite consistent with a gapless spectrum. We estimate the high temperature magnetic susceptibility and compare with previous calculations and with experiment

309

Fish hemoglobins  

OpenAIRE

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 biochemica...

Souza, P. C.; Bonilla-rodriguez, G. O.

2007-01-01

310

Fish hemoglobins  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in english 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.

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

2007-06-01

311

Fish hemoglobins  

Directory of Open Access Journals (Sweden)

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.

P.C. de Souza

2007-06-01

312

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

313

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

Science.gov (United States)

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

Wei, Ran; Mueller, Erich J.

2014-06-01

314

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

Directory of Open Access Journals (Sweden)

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

Jiang Yunyun

2012-01-01

315

Magnetization of undoped 2-leg S = 1/2 spin ladders in La4Sr10Cu24O41  

CERN Document Server

Magnetization data of single crystalline La4Sr10Cu24O41 are presented. In this compound, doped spin chains and undoped spin ladders are realized. The magnetization, at low temperatures, is governed by the chain subsystem with a finite interchain coupling which leads to short range antiferromagnetic spin correlations. At higher temperatures, the response of the chains can be estimated in terms of a Curie-Weiss law. For the ladders, we apply the low-temperature approximation for a S=1/2 2-leg spin ladder by Troyer et al.

Klingeler, R; Ribeiro, P; Hess, C; Büchner, B

2006-01-01

316

An infinite family of superintegrable systems with the fifth Painleve transcendent from higher order ladder operators and supersymmetry  

CERN Document Server

We will discuss how we can obtain new quantum superintegrable Hamiltonians allowing the separation of variables in Cartesian coordinates with higher order integrals of motion from ladder operators. We will discuss also how higher order supersymmetric quantum mechanics can be used to obtain systems with higher order ladder operators and their polynomial Heisenberg algebra. We will present a new family of superintegrable systems involving the fifth Painleve transcendent which possess fourth order ladder operators constructed from second order supersymmetric quantum mechanics. We present the polynomial algebra of this family of superintegrable systems.

Marquette, Ian

2010-01-01

317

Fish Tales  

International Nuclear Information System (INIS)

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 ad 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.

318

Fish Tales  

Energy Technology Data Exchange (ETDEWEB)

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

McLerran, L.

2010-07-06

319

COMPLIANCE STUDIES: WHAT ABOUT THE FISH?  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2013-08-21

320

Hybrid seine for full fish community collections  

Science.gov (United States)

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.

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

2013-01-01

321

Fish welfare: Fish capacity to experience pain  

Directory of Open Access Journals (Sweden)

Full Text Available Teleost fish possess similar nociceptive processing systems to those found in terrestrial vertebrates. It means that they react to potential painful stimuli in a similar manner as mammals and birds. However, the welfare of fish has been the focus of less research than that of higher vertebrates. Humans may affect the welfare of fish through fisheries, aquaculture and a number of other activities. There is scientific evidence to support the assumption that fish have the capacity to experience pain because they possess functional nociceptors, endogenous opioids and opioid receptors, brain structures involved in pain processing and pathways leading from nociceptors to higher brain structures. Also, it is well documented that some anaesthetics and analgesics may reduce nociceptive responses in fish. Behavioural indicators in fish such as lip-rubbing and rocking behaviours are the best proof that fish react to potential painful stimuli. This paper is an overview of some scientific evidence on fish capacity to experience pain.

Vu?ini? Marijana

2009-01-01

322

Microbiological spoilage of fish and fish products  

DEFF Research Database (Denmark)

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

Gram, Lone; Huss, Hans Henrik

1996-01-01

323

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

CERN Document Server

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

Kawano, K; Kawano, Kenro; Takahashi, Minoru

1997-01-01

324

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

International Nuclear Information System (INIS)

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

325

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-12-04

326

Quantum and classical critical phenomena in the frustrated Heisenberg two-leg ladder  

CERN Document Server

The antiferromagnetic Heisenberg model on the two-leg ladder with exchange interactions along the chains, rungs, and diagonals is studied using the Jordan-Wigner transformation and bond-mean-field theory. The inclusion of all three couplings introduces frustration to the system and depending on their relative strengths the ladder can adopt one of three possible magnetically-disordered gapped states. The phase diagram found in this mean-field approach is in very good agreement with the one calculated by Weihong and colleagues using the Lanczos exact diagonalization method. By analyzing the ground-state energy we study quantum criticality when the coupling parameters are varied at zero temperature. We also found that the system shows thermally-induced criticality for some values of the rung and diagonal coupling constants. All the phase transitions encountered in this system occur between disordered phases.

Ramakko, B; Ramakko, Brandon; Azzouz, Mohamed

2007-01-01

327

Enhancement of chaotic subdiffusion in disordered ladders with synthetic gauge fields.  

Science.gov (United States)

We study spreading wave packets in a disordered nonlinear ladder with broken time-reversal symmetry induced by synthetic gauge fields. The model describes the dynamics of interacting bosons in a disordered and driven optical ladder within a mean-field approximation. The second moment of the wave packet m(2)=gt(?) grows subdiffusively with the universal exponent ??1/3 similar to the time-reversal case. However, the prefactor g is strongly modified by the field strength and shows a nonmonotonic dependence. For a weak field, the prefactor increases since time-reversal enhanced backscattering is suppressed. For strong fields the spectrum of the linear wave equation reduces the localization length through the formation of gaps and narrow bands. Consequently the prefactor for the subdiffusive spreading law is suppressed. PMID:25314507

Yu, Xiaoquan; Flach, Sergej

2014-09-01

328

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)

329

Majorana fermions and multiple topological phase transition in Kitaev ladder topological superconductors  

Science.gov (United States)

Motivated by the InSb nanowire superconductor system, we investigate a system where one-dimensional topological superconductors are placed in parallel. It would be simulated well by a ladder of the Kitaev chains. The system undergoes multiple topological phase transitions, where the number of Majorana fermions changes as a function of the interchain superconducting pairings. We analytically determine the topological phase diagram by explicitly calculating the topological number and the band structure. They show even-odd effects with respect to the number of legs of the ladder. When the relative phase between the inter- and intrachain superconducting pairings is 0 or ?, the system belongs to the class BDI characterized by the Z index, and otherwise it belongs to the class D characterized by the Z2 index. This topological class change would be caused by applying the Josephson current or an external magnetic field, and could be observed by measuring the zero-bias differential conductance.

Wakatsuki, Ryohei; Ezawa, Motohiko; Nagaosa, Naoto

2014-05-01

330

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

CERN Document Server

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

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

2005-01-01

331

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

International Nuclear Information System (INIS)

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

332

Studies of quantum spin ladders at T=0 and at high temperatures by series expansions  

CERN Document Server

We have carried out extensive series studies, at T=0 and at high temperatures, of 2-chain and 3-chain spin-half ladder systems with antiferromagnetic intrachain and both antiferromagnetic and ferromagnetic interchain couplings. Our results confirm the existence of a gap in the 2-chain Heisenberg ladders for all non-zero values of the interchain couplings. Complete dispersion relations for the spin-wave excitations are computed. For 3-chain systems, our results are consistent with a gapless spectrum. We also calculate the uniform magnetic susceptibility and specific heat as a function of temperature. We find that as T\\to 0, for the 2-chain system the uniform susceptibility goes rapidly to zero, whereas for the 3-chain system it approaches a finite value. These results are compared in detail with previous studies of finite systems.

Oitmaa, J; Weihong, Z; Singh, Rajiv R P; Weihong, Zheng

1996-01-01

333

Three-ladder vertex in the Reggeon graph technique in QCD  

International Nuclear Information System (INIS)

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

334

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

CERN Document Server

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

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

2007-01-01

335

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

336

Sufficient condition for applying the ladder approximation to the multiple scattering of light in random media  

International Nuclear Information System (INIS)

We have obtained a sufficient condition under which the ladder approximations may be used to decouple the moment equations (e.g., the Bethe-Salpeter equation) that result when one analyzes the propagation of the optical waves in a randomly inhomogeneous medium. Simply stated, this means that the mean free path for multiple scattering by the inhomogeneities is required to be large in comparison with the size of the inhomogeneities

337

Point-like spin-dependent interaction in calculations of self-energy ladder diagrams  

OpenAIRE

An instantaneous and zero-range spin-dependent interaction, derived by summing an infinite number of electron-hole ladder diagrams within a local approximation, is analyzed as a function of the electron gas density and the relative spin polarization. The strength of such an interaction is defined by an integral of a statically screened Coulomb interaction with a spatially localized weighting factor. This weighting factor represents the mutually uncorrelated motion of an elec...

Nechaev, I. A.; Nagy, I.; Echenique, P. M.; Chulkov, E. V.

2006-01-01

338

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

OpenAIRE

We have studied the optical oscillation and tunneling of light waves in optical waveguide ladders formed by two coupled planar optical waveguide arrays. For the band structure, a mid-zone gap is formed due to band hybridization and its wavenumber position can be tuned throughout the whole Brillouin zone, which is different from the Bragg gap. By imposing a gradient in the propagation constant in each array, Bloch-Zener oscillation (BZO) is realized with Zener tunneling betwe...

Zheng, Ming Jie; Wang, Gang; Yu, Kin Wah

2010-01-01

339

Demand pull and technology push effects in the quality ladder model  

OpenAIRE

This paper extends the standard quality ladder model of innovation and quality growth by allowing for heterogeneous industries. This enables us not only to deal with the Schumpeterian hypothesis about market power and innovation, but also to analyze industry specific demand pull and technology push effects. In accordance with the empirical evidence, we show that perspective of large market power, favorable technological opportunities and high demand expectations as well as the economy-wide en...

Stadler, Manfred

2000-01-01

340

Theoretical, Experimental, and Computational Evaluation of a Tunnel Ladder Slow-Wave Structure  

Science.gov (United States)

The dispersion characteristics of a tunnel ladder circuit in a ridged wave guide were experimentally measured and determined by computer simulation using the electromagnetic code MAFIA. To qualitatively estimate interaction impedances, resonance frequency shifts due to a perturbing dielectric rod along the axis were also measured indicating the axial electric field strength. A theoretical modeling of the electric and magnetic fields in the tunnel area was also done.

Wallett, Thomas M.; Qureshi, A. Haq

1994-01-01

341

Anomalous thermal conductivity of frustrated Heisenberg spin-chains and ladders  

OpenAIRE

We study the thermal transport properties of several quantum spin chains and ladders. We find indications for a diverging thermal conductivity at finite temperatures for the models examined. 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 result of the microscopic approach leads to a substantial reduction for estimat...

Alvarez, J. V.; Gros, Claudius

2002-01-01

342

Spin Excitations in the Two-leg Ladder Antiferromagnet CaV$_2$O$_5$  

CERN Document Server

The nuclear spin-lattice relaxation rate (1/T1) at the V sites in CaV2O5 was measured. The result was compared with the calculation for the two-leg ladder with the strong-coupling expansion. We found a good agreement on the temperature and magnetic field dependence but a discrepancy between the exchange parameters deduced from 1/T1 and the magnetic susceptibility.

Ohama, T; Ueda, Y; Ohama, Tetsuo; Isobe, Masahiko; Ueda, Yutaka

2000-01-01

343

Absence of gap for infinite half-integer spin ladders with an odd number of legs  

CERN Document Server

A proof is presented for the absence of gap for spin 1/2 ladders with an odd number of legs, in the infinite leg length limit. This result is relevant to the current discussion of coupled one--dimensional spin systems, a physical realization of which are vanadyl pyrophosphate, (VO)_2P_2O_7, and stoichiometric Sr_{n-1} Cu_{n+1} O_{2n} (with n=3,5,7,9,\\dots).

Rojo, A G

1995-01-01

344

Exact spontaneous plaquette ground states for high-spin ladder models  

OpenAIRE

We study the exchange physics in high spin Mott insulating systems with $S=3/2$ which is realizable in ultracold atomic systems. The high symmetry of SO(5) or SU(4) therein renders stronger quantum fluctuations than the usual spin-1/2 systems. A spontaneous plaquette ground state without any site and bond spin orders is rigorously proved in a ladder spin-3/2 model, whose topological excitations exhibit fractionalization behavior. The generalization to the SU(N) plaquette sta...

Chen, Shu; Wu, Congjun; Zhang, Shou-cheng; Wang, Yupeng

2005-01-01

345

Saddle Points and Stark Ladders: Exact Calculations of Exciton Spectra in Superlattices  

OpenAIRE

A new, exact method for calculating excitonic absorption in superlattices is described. It is used to obtain high resolution spectra showing the saddle point exciton feature near the top of the miniband. The evolution of this feature is followed through a series of structures with increasing miniband width. The Stark ladder of peaks produced by an axial electric field is investigated, and it is shown that for weak fields the line shapes are strongly modified by coupling to c...

Whittaker, D. M.

1994-01-01

346

Hole crystallization in the spin ladder of Sr14Cu24O41  

CERN Document Server

One of the deepest questions in condensed matter physics concerns what other phases compete with superconductivity in high-transition-temperature (high-Tc) superconductors. One candidate is the "stripe" phase, in which the carriers (holes) condense into rivers of charge separating regions of antiferromagnetism. A related but lesser known system is the "spin ladder", which consists of two coupled chains of magnetic ions forming an array of rungs. A doped ladder can be thought of as a high-Tc material with lower dimensionality, and has been predicted to exhibit both superconductivity and an insulating "hole crystal" phase in which the carriers are localised through many-body interactions. The competition between the two resembles that between static stripes and superconductivity in high-Tc materials. Here we report evidence, from resonant x-ray scattering, for the existence of a hole crystal in the doped spin ladder of Sr14Cu24O41. This phase exists without a detectable distortion in the structural lattice, ind...

Abbamonte, P; Rusydi, A; Gozar, A; Evans, P G; Siegrist, T; Venema, L; Eisaki, H; Isaacs, E D; Sawatzky, G A

2004-01-01

347

Single-particle spectral function of quarter-filled ladder systems  

CERN Document Server

We study the single-particle properties of quarter-filled ladder systems such as sodium vanadate by means of a recently developed generalization of the variational cluster perturbation theory to extended Hubbard models. We find a homogeneous antiferromagnetic insulating phase for nearest-neighbor repulsions smaller than a critical value, without any metallic phase for small repulsions. Different from C-DMFT and LDA considerations, the inclusion of diagonal hopping within a ladder has little effect on the bonding bands, while flattening and shifting the antibonding bands. In the low-temperature charge-ordered phase, the spectrum depends on whether the ordering is driven by the Coulomb repulsion or by the coupling to a static lattice distortion. The small change of the experimentally observed gap upon charge ordering implies that the lattice coupling plays an important role in this ordering. Inter-ladder coupling is straightforward to include within our method. We show that it has only a minor effect on the spe...

Aichhorn, M; Evertz, H G

2004-01-01

348

The Pan-STARRS 1 Photometric Reference Ladder, Release 12.0  

CERN Document Server

As of 2012 Jan 21, the Pan-STARRS 1 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_p1, r_p1, i_p1, z_p1, y_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 releases to be generated as the survey coverage increases and the data analysis improves. The Photometric Ladder has rungs every hour in RA and at 4 intervals in declination. We will release updates with increased area coverage (more rungs) from the latest dataset until the PS1 survey and the final re-reduction are completed. The currently released catalog presents photometry of \\approx 1000 objects per square degree in the rungs of the ladder. Saturation occurs at g_p1, r_p1, i_p1 \\approx 13.5; z_p1 \\approx 13.0; and y_p1 \\approx 12.0. Photometry is provided for stars dow...

Magnier, E A; Finkbeiner, D; 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, C W

2013-01-01

349

Up from Poverty; New Career Ladders for Nonprofessionals.  

Science.gov (United States)

The 23 essays in this collection (1) discuss the movement to provide careers for poor non-professionals as an economic and social reform, (2) describe new careers occupations in social welfare, education, the health services, corrections, and industry, and (3) offer guidelines for designing new careers occupations and for training nonprofessionals.

Riessman, Frank; Popper, Hermine I.

350

Traditional fishing tools  

Directory of Open Access Journals (Sweden)

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.

STOICA Georgeta

2009-09-01

351

Video Gallery: Fishes and Water  

Science.gov (United States)

This gallery of online resources is from the Museum's Seminars on Science, a series of distance-learning courses designed to help educators meet the new national science standards. This gallery, part of the Diversity of Fishes seminar, features two videos that both have printable PDF transcripts. About Water looks at how the water that covers two-thirds of our planet is distributed in oceans, polar caps, aquifers, rivers, and lakes. Planet Water discusses how freshwater fish, which make up one-quarter of all vertebrate biodiversity on Earth,live in less than 1/100th of a percent of the planet's water.

352

Validation of a hydride generation atomic absorption spectrometry methodology for determination of mercury in fish designed for application in the Brazilian national residue control plan.  

Science.gov (United States)

In the present study, a method for the determination of mercury (Hg) in fish was validated according to ISO/IEC 17025, INMETRO (Brazil), and more recent European recommendations (Commission Decision 2007/333/EC and 2002/657/EC) for implementation in the Brazilian Residue Control Plan (NRCP) in routine applications. The parameters evaluated in the validation were investigated in detail. The results obtained for limit of detection and quantification were respectively, 2.36 and 7.88 ?g kg(-1) of Hg. While the recovery varies between 90-96%. The coefficient of variation was of 4.06-8.94% for the repeatability. Furthermore, a comparison using an external proficiency testing scheme was realized. The results of method validated for the determination of the mercury in fish by Hydride generation atomic absorption spectrometry were considered suitable for implementation in routine analysis. PMID:24007488

Damin, Isabel C F; Santo, Maria A E; Hennigen, Rosmari; Vargas, Denise M

2013-01-01

353

Fish under exercise  

OpenAIRE

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...

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

2011-01-01

354

Laboratory Studies on the Effects of Shear on Fish  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2000-09-20

355

Consumer beliefs regarding farmed versus wild fish.  

Science.gov (United States)

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

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

356

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

OpenAIRE

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 tr...

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

2011-01-01

357

Augmented Fish Health Monitoring, 1992 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

The Augmented Fish Health Monitoring Project (Project) had its origin, in the mid-1980's, in perceived differences or inconsistencies in fish disease detection, diagnosis and control capabilities between the five conservation agencies rearing and releasing anadromous salmonids for fishery resource management and mitigation purposes in the Columbia River basin. Agency fish health programs varied greatly. Some agencies had personnel, equipment and funding to frequently monitor the health status of both juvenile production fish and adult salmon or steelhead trout at the time of spawning. Other agencies had much smaller programs and limited resources. These differences became better understood when the Pacific Northwest Fish Health Protection Committee developed its Model Fish Health Protection Program including recommendations for standard fish disease detection procedures. Even though some agencies could not immediately attain the goals set by the Model Program it was unanimously adopted as a desirable objective. Shortly thereafter, a multi-party planning group was assembled to help the Bonneville Power Administration (BPA) find ways to improve agency fish health programs and implement measures under the Fish and Wildlife Program of the Northwest Power Planning Council. The planning group assessed existing agency fish health monitoring capabilities, agreed upon satisfactory levels of capability to detect and identify important fish pathogens, and designed a five-year project establishing comparable fish health monitoring capability in each agency. It was strongly believed that such a project would improve the health and quality of the millions of hatchery fish released annually in the Columbia River basin and improve interagency communications and disease control coordination. During 1986 and 1987 BPA individually negotiated five separate contracts with the fishery agencies to standardize fish health monitoring, develop a common data collection and reporting format, evaluate and monitor hatchery water supplies, improve communications and coordination, and provide a mechanism for periodic review. The contract with the U. S. Fish and Wildlife Service was approved on May 31, 1987, the last of the five inter-agency agreements to be signed. This did not delay Service participation with the other agencies because the Service already had many elements of the Project in place under its existing Service-wide fish health policy and implementation plan, The Service fully participated in the Project from mid-1987 through mid-1992. This completion report describes some of the many accomplishments under each of the objectives, benefits accruing from the Project, elements to be sustained by the Service after the Project ended, and Project that were not completed or that pointed out new work that needs to be done.

Warren, James W.

1992-08-01

358

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

CERN Document Server

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

Tan, Chaohua

2013-01-01

359

Ladder-shaped lymphaticovenular anastomosis using multiple side-to-side lymphatic anastomoses for a leg lymphedema patient.  

Science.gov (United States)

Lymphatic supermicrosurgery, supermicrosurgical lymphaticovenular anastomosis (LVA), is becoming a useful option for the treatment of compression-refractory lymphedema. One of the most important points in LVA is to make as many bypasses as possible for better treatment results. We report a progressive lower extremity lymphedema (LEL) case successfully treated with a ladder-shaped LVA. A 67-year-old female with secondary LEL refractory to conservative treatments underwent LVA. A ladder-shaped LVA was performed at the left ankle. In the ladder-shaped LVA, 3 lymphatic vessels and 1 vein were anastomosed in a side-to-side fashion; 2 lymphatic vessels next to the vein were anastomosed to the vein, and the other lymphatic vessel was anastomosed to the nearby lymphatic vessel. Using ladder-shaped LVA, 6 lymph flows of 3 lymphatic vessels could be bypassed into a vein. Six months after the LVA operation, her left LEL index decreased from 212 to 195, indicating edematous volume reduction. Ladder-shaped LVA may be a useful option when there are 3 lymphatic vessels and 1 vein in a surgical field. PMID:24375825

Yamamoto, Takumi; Kikuchi, Kazuki; Yoshimatsu, Hidehiko; Koshima, Isao

2014-07-01

360

Hydraulic evaluation of fish attraction potential at Merwin Dam fish collection facilities  

International Nuclear Information System (INIS)

This paper discussed a 1:24 scale physical model constructed to optimize a proposed fish trap entrance for a hydroelectric project located on the Lewis River in Washington state. The fish trap entrance will be placed at the Merwin dam, which is located at the furthest point downstream of the main project. The new adult fish passage facilities will collect, sort, and transport adult fish migrating upstream from the ocean. The physical model was used to confirm the preliminary entrance locations as well as to evaluate attraction flows and optimize entrance weir designs. A pump station intake arrangement was also designed to supply fishway attraction flow. It was concluded that the model will also be used to document tailrace flow patterns in order to assist with future studies of fish behavior and dams. 5 figs.

361

Hydraulic evaluation of fish attraction potential at Merwin Dam fish collection facilities  

Energy Technology Data Exchange (ETDEWEB)

This paper discussed a 1:24 scale physical model constructed to optimize a proposed fish trap entrance for a hydroelectric project located on the Lewis River in Washington state. The fish trap entrance will be placed at the Merwin dam, which is located at the furthest point downstream of the main project. The new adult fish passage facilities will collect, sort, and transport adult fish migrating upstream from the ocean. The physical model was used to confirm the preliminary entrance locations as well as to evaluate attraction flows and optimize entrance weir designs. A pump station intake arrangement was also designed to supply fishway attraction flow. It was concluded that the model will also be used to document tailrace flow patterns in order to assist with future studies of fish behavior and dams. 5 figs.

Ball, A.; Larson, L. [Northwest Hydraulic Consultants Inc., Seattle, WA (United States); Adams, A.; Shrier, F. [PacifiCorp, Portland, OR (United States); Nigus, M. [Black and Veatch, Kansas City, MO (United States); Postlewait, D. [R2 Resource Consultants Inc., Redmond, WA (United States)

2009-07-01

362

THE PAN-STARRS 1 PHOTOMETRIC REFERENCE LADDER, RELEASE 12.01  

International Nuclear Information System (INIS)

As of 2012 January 21, the Pan-STARRS 1 3? Survey has observed the 3/4 of the sky visible from Hawaii with a minimum of 2 and mean of 7.6 observations in five filters, g P1, r P1, i P1, z P1, y 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 data set. This article describes the PS1 Photometric Ladder, Release 12.01. This is the first of a series of data releases to be generated as the survey coverage increases and the data analysis improves. The Photometric Ladder has rungs every hour in right ascension and at four intervals in declination. We will release updates with increased area coverage (more rungs) from the latest data set until the PS1 survey and the final re-reduction are completed. The currently released catalog presents photometry of ?1000 objects per square degree in the rungs of the ladder. Saturation occurs at g P1, r P1, i P1 ? 13.5; z P1 ? 13.0; and y P1 ? 12.0. Photometry is provided for stars down to g P1, r P1, i P1 ? 19.1 in the AB system. This data release depends on the rigid 'Ubercal' photometric calibration using only the photometric nights, with systematic uncertainties of (8.0, 7.0, 9.0, 10.7, 12.4) mmag in (g P1, r P1, i P1, z P1, y P1). Area1, y P1). Areas covered only with lower quality nights are also included, and have been tied to the Ubercal solution via relative photometry; photometric accuracy of the non-photometric regions is lower and should be used with caution.

363

Donor-acceptor conjugated polymers based on multifused ladder-type arenes for organic solar cells.  

Science.gov (United States)

Harvesting solar energy from sunlight to generate electricity is considered as one of the most important technologies to address the future sustainability of humans. Polymer solar cells (PSCs) have attracted tremendous interest and attention over the past two decades due to their potential advantage to be fabricated onto large area and light-weight flexible substrates by solution processing at a lower cost. PSCs based on the concept of bulk heterojunction (BHJ) configuration where an active layer comprises a composite of a p-type (donor) and an n-type (acceptor) material represents the most useful strategy to maximize the internal donor-acceptor interfacial area allowing for efficient charge separation. Fullerene derivatives such as [6,6]-phenyl-C61?or?71-butyric acid methyl ester (PCBM) are the ideal n-type materials ubiquitously used for BHJ solar cells. The major effort to develop photoactive materials is numerously focused on the p-type conjugated polymers which are generally synthesized by polymerization of electron-rich donor and electron-deficient acceptor monomers. Compared to the development of electron-deficient comonomers (acceptor segments), the development of electron-rich donor materials is considerably flourishing. Forced planarization by covalently fastening adjacent aromatic and heteroaromatic subunits leads to the formation of ladder-type conjugated structures which are capable of elongating effective conjugation, reducing the optical bandgap, promoting intermolecular ?-? interactions and enhancing intrinsic charge mobility. In this review, we will summarize the recent progress on the development of various well-defined new ladder-type conjugated materials. These materials serve as the superb donor monomers to prepare a range of donor-acceptor semi-ladder copolymers with sufficient solution-processability for solar cell applications. PMID:25322211

Wu, Jhong-Sian; Cheng, Sheng-Wen; Cheng, Yen-Ju; Hsu, Chain-Shu

2014-10-16

364

Scaffolding, ladders, chains, and rare ferrimagnetism in intermetallic borides: synthesis, crystal chemistry and magnetism.  

Science.gov (United States)

Single-phase polycrystalline samples and single crystals of the complex boride phases Ti(8)Fe(3)Ru(18)B(8) and Ti(7)Fe(4)Ru(18)B(8) have been synthesized by arc melting the elements. The phases were characterized by powder and single-crystal X-ray diffraction as well as energy-dispersive X-ray analysis. They are new substitutional variants of the Zn(11)Rh(18)B(8) structure type, space group P4/mbm (no. 127). The particularity of their crystal structure lies in the simultaneous presence of dumbbells which form ladders of magnetically active iron atoms along the [001] direction and two additional mixed iron/titanium chains occupying Wyckoff sites 4h and 2b. The ladder substructure is ca. 3.0 Å from the two chains at the 4h, which creates the sequence chain-ladder-chain, establishing a new structural and magnetic motif, the scaffold. The other chain (at 2b) is separated by at least 6.5 Å from this scaffold. According to magnetization measurements, Ti(8)Fe(3)Ru(18)B(8) and Ti(7)Fe(4)Ru(18)B(8) order ferrimagnetically below 210 and 220 K, respectively, with the latter having much higher magnetic moments than the former. However, the magnetic moment observed for Ti(8)Fe(3)Ru(18)B(8) is unexpectedly smaller than the recently reported Ti(9)Fe(2)Ru(18)B(8) ferromagnet. The variation of the magnetic moments observed in these new phases can be adequately understood by assuming a ferrimagnetic ordering involving the three different iron sites. Furthermore, the recorded hysteresis loops indicate a semihard magnetic behavior for the two phases. The highest H(c) value (28.6 kA/m), measured for Ti(7)Fe(4)Ru(18)B(8), lies just at the border of those of hard magnetic materials. PMID:21634389

Goerens, Christian; Brgoch, Jakoah; Miller, Gordon J; Fokwa, Boniface P T

2011-07-01

365

Phenotypic, antigenic, and molecular characterization of Pasteurella piscicida strains isolated from fish.  

Science.gov (United States)

We compared Pasteurella piscicida strains isolated from different fish species in several European countries with strains isolated in Japan and the United States. The taxonomic analysis revealed that, regardless of the geographic origin and source of isolation, all the strains exhibited the same biochemical and physiological characteristics. Serological assays with different rabbit antisera demonstrated a high level of antigenic similarity among strains, with cross-agglutination titers of 20,480 to 40,960. This serological homogeneity was supported by the lipopolysaccharide (LPS) and membrane protein profiles. All the P. piscicida strains had the same electrophoretic LPS pattern, showing O side chains with a ladder-like structure, and shared at least four major outer membrane proteins, of 20, 30, 42, and 53 kDa. Western blot (immunoblot) analysis with LPS and protein indicated that all the P. piscicida strains are immunologically related. In addition, the chromosomal DNA fingerprint patterns obtained for the European strains with the enzymes EcoRI and BamHI were practically identical to those of the Japanese and U.S. strains. Although some differences were found in the plasmid profiles of P. piscicida, a large number of strains possessed in common plasmid bands of 20 and 7 MDa. In addition, a plasmid of 50 MDa was present in the majority of the European strains. Restriction endonuclease analysis demonstrated the genetic homology of the plasmid bands shared by most of the European strains. All the P. piscicida strains had the same drug resistance patterns, indicating that a correlation between plasmid carriage and resistance to a specific antimicrobial agent cannot be established. The high levels of phenotypic, serological, and genetic homogeneity found among the P. piscicida strains should facilitate the development of DNA probes with diagnostic purposes as well as the design of effective vaccines. PMID:1444366

Magariños, B; Romalde, J L; Bandín, I; Fouz, B; Toranzo, A E

1992-10-01

366

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

International Nuclear Information System (INIS)

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

367

Technological Progress and Market Growth : An Empirical Study Based on the Quality-Ladder Approach  

OpenAIRE

This paper develops an extended version of the quality-ladder model by allowing for heterogeneous markets. Based on this model, it presents an empirical analysis of innovation-based growth at the market level using a technometric measurement concept. It can be shown that a growth-promoting effect due to technological progress in a particular, single year is observed after between two and up to seven years. This is true not only for highly innovative markets, but also for those in which fewer ...

Grupp, Hariolf; Stadler, Manfred

2004-01-01

368

Point-like spin-dependent interaction in calculations of self-energy ladder diagrams  

CERN Document Server

An instantaneous and zero-range spin-dependent interaction, derived by summing an infinite number of electron-hole ladder diagrams within a local approximation, is analyzed as a function of the electron gas density and the relative spin polarization. The strength of such an interaction is defined by an integral of a statically screened Coulomb interaction with a spatially localized weighting factor. This weighting factor represents the mutually uncorrelated motion of an electron-hole pair in singlet or triplet spin states ($S^z=0,\\pm1$). An implementation, based on a Yukawa-type interaction with a spin-polarization-dependent Thomas-Fermi screening length, is given.

Nechaev, I A; Echenique, P M; Chulkov, E V

2006-01-01

369

Step-ladder Rabi oscillations in molecules exposed to intense ultrashort vuv pulses  

International Nuclear Information System (INIS)

We theoretically investigate the production of Rabi-type oscillations in two-photon resonant ionization of H2 by intense ultrashort vuv pulses. We show that, with such pulses, oscillations proceed through a step-ladder mechanism that successively involves higher and higher vibrational levels of the lower and upper electronic states. The consequences of this mechanism are (i) the relatively large proportion of H2 molecules in excited electronic states not accessible by direct photon absorption, (ii) the splitting in the energy distribution of ionized electrons, and (iii) the unusually broad (non-Franck-Condon) vibrational distribution of both H2 and H2+

370

Statics and dynamics of weakly coupled antiferromagnetic spin-1/2 ladders in a magnetic field  

OpenAIRE

We investigate weakly coupled spin-1/2 ladders in a magnetic field. The work is motivated by recent experiments on the compound (C5H12N)2CuBr4 (BPCB). We use a combination of numerical and analytical methods, in particular the density matrix renormalization group (DMRG) technique, to explore the phase diagram and the excitation spectra of such a system. We give detailed results on the temperature dependence of the magnetization and the specific heat, and the magnetic field d...

Bouillot, Pierre

2010-01-01

371

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

CERN Document Server

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

Williams, Richard

2009-01-01

372

Chirped Multi-photon adiabatic passage for a four-level ladder-type Rydberg excitation  

CERN Document Server

We develop a multi-photon adiabatic passage to realize a highly efficient Rydberg excitation in a four-level ladder-type atomic system. The adiabatic passage is based on the existence of a novel quasi-dark state in the cascade excitation system where the frequencies of the lasers are appropriately chirped with time. We also investigate the influence of the interatomic Rydberg interaction on the passage and extend its application to the preparation of anti-blockade Rydberg atom pairs in the Rydberg blockade regime.

Qian, Jing; Zhang, Lu; Zhang, Weiping

2015-01-01

373

Spectral and thermodynamic properties of a strong-leg quantum spin ladder.  

Science.gov (United States)

The strong-leg S=1/2 Heisenberg spin ladder system (C(7)H(10)N)(2)CuBr(4) is investigated using density matrix renormalization group calculations, inelastic neutron scattering, and bulk magnetothermodynamic measurements. Measurements showed qualitative differences compared to the strong-rung case. A long-lived two-triplon bound state is confirmed to persist across most of the Brillouin zone in a zero field. In applied fields, in the Tomonaga-Luttinger spin-liquid phase, elementary excitations are attractive, rather than repulsive. In the presence of weak interladder interactions, the strong-leg system is considerably more prone to three-dimensional ordering. PMID:22680751

Schmidiger, D; Bouillot, P; Mühlbauer, S; Gvasaliya, S; Kollath, C; Giamarchi, T; Zheludev, A

2012-04-20

374

Role of quadratic and cubic spectral phases in ladder climbing with ultrashort pulses  

International Nuclear Information System (INIS)

Two-photon excitation of a quantum ladder system by an ultrashort chirped pulse leads to interferences in the excited-state population, between direct and sequential paths. Experimental results have been obtained in atomic sodium vapor. The presence of several intermediate and final states leads to new phenomena. The interplay between the two sequential paths leads to strongly contrasted oscillations and a large enhancement of the transition probability for precise values of the chirp. A cubic spectral phase modifies significantly the behavior of the quantum interferences and can be used to enhance the two-photon absorption rate

375

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

OpenAIRE

Ladder polyphenylsilsesquioxane (Ph-LPSQ) has been synthesized at 80°C through the hydrolysis and condensation of phenyltrichlorosilane (PhSiCl3), with aluminum chloride (AlCl3) or magnesium chloride (MgCl2) as an assistant reactant. The Ph-LPSQ obtained has been characterized and analyzed by SEM, FTIR, TGA, 29Si NMR, and MALDI-TOF MS, and the effects of AlCl3and MgCl2on the structure regularity of Ph-LPSQ and the condensation polymerizationhavealso been studied. The results showed tha...

Jiang Yunyun; Yang Rongjie

2012-01-01

376

Two-leg fermionic Hubbard ladder system in the presence of state-dependent hopping  

Science.gov (United States)

We study a two-leg fermionic Hubbard ladder model with a state-dependent hopping. We find that, contrary to the case without a state-dependent hopping, for which the system has a superfluid nature regardless of the sign of the interaction at incommensurate filling, in the presence of such a hopping a spin-triplet superfluid, spin-density wave, and charge-density wave phases emerge. We examine our results in the light of recent experiments on periodically driven optical lattices in cold atoms. We give protocols allowing us to realize the spin-triplet superfluid elusive in the cold atoms.

Uchino, Shun; Giamarchi, Thierry

2015-01-01

377

Quantum spin ladder systems associated with su(2 vertical bar 2)  

International Nuclear Information System (INIS)

Two integrable quantum spin ladder systems will be introduced associated with the fundamental su(2 vertical bar 2) solution of the Yang-Baxter equation. The first model is a generalized quantum Ising system with Ising rung interactions. In the second model the addition of extra interactions allows us to impose Heisenberg rung interactions without violating integrability. The existence of a Bethe ansatz solution for both models allows us to investigate the elementary excitations for antiferromagnetic rung couplings. We find that the first model does not show a gap whilst in the second case there is a gap for all positive values of the rung coupling. (author). Letter-to-the-editor

378

Studies of the t-J two-leg ladder via series expansions  

OpenAIRE

Series expansions at T=0 are used to study properties of the half-filled $t-J$ ladder doped with one or two holes, and at quarter filling. Dispersion curves are obtained for one-hole symmetric and antisymmetric (bonding and antibonding) excitations and for the two-hole bound state. The line in the phase diagram which separates bound and unbound states is determined. For quarter filling we compute the ground state energy and estimate the location of the phase separation line....

Oitmaa, J.; Hamer, C. J.; Weihong, Zheng

1999-01-01

379

Studies of the t-J two-leg ladder via series expansions  

CERN Document Server

Series expansions at T=0 are used to study properties of the half-filled t-J ladder doped with one or two holes, and at quarter filling. Dispersion curves are obtained for one-hole symmetric and antisymmetric (bonding and antibonding) excitations and for the two-hole bound state. The line in the phase diagram which separates bound and unbound states is determined. For quarter filling we compute the ground state energy and estimate the location of the phase separation line. Comparisons with other numerical and analytical results are presented.

Oitmaa, J; Weihong, Z; Weihong, Zheng

1999-01-01

380

Susceptibility and excitation spectrum of (VO)2P2O7 in ladder and dimer-chain models  

International Nuclear Information System (INIS)

We present numerical results for the magnetic susceptibility of a Heisenberg antiferromagnetic spin ladder as a function of temperature and the spin-spin interaction strengths Jperpendicular and Jparallel. These are contrasted with bulk-limit results for the dimer chain. A fit to the experimental susceptibility of the candidate spin-ladder compound vanadyl pyrophosphate, (VO)2P2O7, gives the parameters Jperpendicular=7.82 meV and Jparallel=7.76 meV. With these values we predict a singlet-triplet energy gap of Egap=3.9 meV, and give a numerical estimate of the ladder triplet dispersion relation ?(k). In contrast, a fit to the dimer-chain model leads to J1=11.11 meV and J2=8.02 meV, which predicts a gap of Egap=4.9 meV

381

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

Science.gov (United States)

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.

Akibue, Seiseki; Murao, Mio

2014-12-01

382

The susceptibility and excitation spectrum of (VO)$_{2}$P$_{2}$O$_{7}$ in ladder and dimer chain models  

CERN Document Server

We present numerical results for the magnetic susceptibility of a Heisenberg antiferromagnetic spin ladder, as a function of temperature and the spin-spin interaction strengths J_\\perp and J_{||}. These are contrasted with new bulk limit results for the dimer chain. A fit to the experimental susceptibility of the candidate spin-ladder compound vanadyl pyrophosphate, (VO)_2P_2O_7, gives the parameters J_\\perp = 7.82 meV and J_{||} = 7.76 meV. With these values we predict a singlet-triplet energy gap of E_{gap} = 3.9 meV, and give a numerical estimate of the ladder triplet dispersion relation \\omega(k). In contrast, a fit to the dimer chain model leads to J_1=11.11 meV and J_2=8.02 meV, which predicts a gap of E_{gap} = 4.9 meV.

Barnes, T

1994-01-01

383

A neutron scattering study of magnetic excitations in the spin ladder (VO)$_{2}$P$_{2}$O$_{7}$  

CERN Document Server

In this letter we report results from inelastic neutron scattering experiments on powder samples of vanadyl pyrophosphate, (VO)2P2O7. We see evidence for three magnetic excitations, at 3.5 meV, 6.0 meV and 14 meV. The intensity of the 3.5 meV mode is strong near Q=0.8 A-1, consistent with the one-magnon gap mode reported previously and predicted by the spin-ladder model. The magnetic scattering at 14 meV may be due to the top of the one-magnon band or the two-magnon continuum predicted in the ladder model. The 6.0 meV mode also peaks in intensity at Q=0.8 A-1. This mode has not been reported previously and was not anticipated by existing theoretical treatments of the spin ladder.

Garrett, A W; Barnes, T; Sales, B C

1996-01-01

384

SAMPLE FISH DATA, NC  

Science.gov (United States)

Fish data at sample locations in the Albemarle-Pamlico Estuary watershed, 1993-1995. See http://sgi1dncrlg.er.usgs.gov/albe-html/biology/fish/fishdatadic.html for list of fields and their meanings....

385

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

386

Variability of fish consumption within the 10 European countries participating in the European Investigation into Cancer and Nutrition (EPIC) study.  

OpenAIRE

Objective: To describe and compare the consumption of total fish (marine foods) and the fish sub-groups - white fish, fatty fish, very fatty fish, fish products and crustacea, in participants from the European Investigation into Cancer and Nutrition (EPIC) study. Design: Cross-sectional analysis of dietary intake using a computerised standardised 24-hour recall interview. Crude means, means and standard errors adjusted by age, season and day of the week were calculated, stratified by centre a...

Welch, Aa; Lund, E.; Amiano, P.; Dorronsoro, M.; Brustad, M.; Kumle, M.; Rodriguez, M.; Lasheras, C.; Janzon, L.; Jansson, J.; Luben, R.; Spencer, Ea; Overvad, K.; Tjønneland, A.; Clavel-chapelon, F.

2002-01-01

387

Fish Family Identification  

Science.gov (United States)

In this game, students will become familiar with fish shapes, learn that fish within a given taxonomic family have similar body shapes, and discuss how different body shapes enable fish to survive in their environments. This activity enhances learners' abilities at making careful observations about each shape and supports an understanding that there are many different kinds of fish, each adapted to its own environment. This standards-based activity includes wrap-up suggestions and background for educators.

Sciences, California A.

2008-01-01

388

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

OpenAIRE

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...

Southwell, Maura; Galassi, Maria; Mcrobert, Scott

2012-01-01

389

Ciguatera fish poisoning  

OpenAIRE

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

Falck, Troy M.; Suchard, Jeffrey R.

1999-01-01

390

Got a Sick Fish?  

Science.gov (United States)

... Care Animal Welfare Veterinary Careers Public Health Got a sick fish? Fish with disease can show a variety of signs. If you notice your pet ... disease seen in pet fish: Appearing disoriented, such as swimming upside down Leaving food uneaten White spots ...

391

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

DEFF Research Database (Denmark)

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 with olive 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.

Olsen, SF; Østerdal, ML

2007-01-01

392

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

DEFF Research Database (Denmark)

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.

HØst, Jeppe Engset

2012-01-01

393

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

CERN Document Server

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 ...

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

394

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)

395

Ladder Oligo(m-aniline)s: Derivatives of Azaacenes with Cross-Conjugated [pi]-Systems  

Energy Technology Data Exchange (ETDEWEB)

We describe the synthesis and electronic properties of ladder oligomers of poly(m-aniline) that may be considered as derivatives of azaacenes with cross-conjugated {pi}-systems. Syntheses of ladder oligo(m-aniline)s with 9 and 13 collinearly fused six-membered rings employed Pd-catalyzed aminations and Friedel-Crafts-based ring closures. Structures were confirmed by either X-ray crystallography or correlations between DFT-computed and experimental spectroscopic data such as {sup 1}H, {sup 13}C, and {sup 15}N NMR chemical shifts and electronic absorption spectra. All compounds have planar 'azaacene' moieties. The experimental band gaps E{sub g} {approx} 3.5-3.65 eV, determined by the UV-vis absorption onsets, were in agreement with the TD-DFT-computed vertical excitation energies to the S{sub 1} state. Fluorescence quantum yields of up to 20% were found. Electrochemically estimated HOMO energies of -4.8 eV suggested propensity for a facile one-electron oxidation and just sufficient environmental stability toward oxygen (O{sub 2}). For two oligomers with 'tetraazanonacene' moieties, potentials of E{sup 4+/3+} {approx} 1.6-1.7 V vs SCE were determined for four-electron oxidation to the corresponding tetraradical tetracations.

Rajca, Andrzej; Boraty; #324; ski, Przemys; #322; aw J.; Olankitwanit, Arnon; Shiraishi, Kouichi; Pink, Maren; Rajca, Suchada (UNL); (Indiana)

2012-04-30

396

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

Science.gov (United States)

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

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

2014-01-01

397

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

Science.gov (United States)

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

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

2014-08-01

398

Tropical Fish Rescue  

Science.gov (United States)

Millions of fish eggs from the Caribbean get stuck in the gulf stream every year and drift thousands of miles north where they hatch. Unfortunately, when winter comes, the baby fish will die. In this video, Jonathan joins the New England Aquarium Dive Club on a tropical fish rescue in Rhode Island where they catch some of these fish in the fall before water temperatures plummet. The fish go to the New England Aquariumâs exhibits. Please see the accompanying study guide for educational objectives and discussion points.

Productions, Jonathan B.

2010-02-01

399

Turbine related fish mortality  

International Nuclear Information System (INIS)

A literature review was conducted to assess the factors affecting turbine-related fish mortality. The mechanics of fish passage through a turbine is outlined, and various turbine related stresses are described, including pressure and shear effects, hydraulic head, turbine efficiency, and tailwater level. The methodologies used in determining the effects of fish passage are evaluated. The necessity of adequate controls in each test is noted. It is concluded that mortality is the result of several factors such as hardiness of study fish, fish size, concentrations of dissolved gases, and amounts of cavitation. Comparisons between Francis and Kaplan turbines indicate little difference in percent mortality. 27 refs., 5 figs

400

FISH PRODUCTION WORLDWIDE  

Directory of Open Access Journals (Sweden)

Full Text Available Fishing is one of the oldest occupations, which over the years has gone through several stages. In the economic terms the increase in intensive industrial system of the fish is advantageous because the specific energy consumption is low, given that they not need to maintain body temperature at high temperatures. Having regard to demographic trends in continue increasing, and the tendency of decrease fisheries leads to increased the production of aquaculture fish by order to ensure enough quantity and quality. The purpose of this paper is to highlight the evolution of fish production worldwide and in particular to show the evolution of production of fish from fisheries and aquaculture. To highlight the evolution global fish production given two ways to get fish respectively from aquaculture and fisheries, that have used data from FAOSTAT for 2007-2012. Also we can see that approximately 90% of the fish production is fished in the sea and only 10% in the territorial waters. The fish production in Africa had an ascending trend in the period under review. Analyzing fish production the share of total world continents is noted that Asia has a share of 68% in 2007 and increase to 73% in 2012.

Georgiana Melania COSTAICHE

2014-12-01

401

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

402

Yakima Basin Fish Passage Project, Phase 2  

Energy Technology Data Exchange (ETDEWEB)

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.

1991-08-01

403

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

404

Resummation of in-medium ladder diagrams: s-wave effective range and p-wave interaction  

Science.gov (United States)

A recent work on the resummation of fermionic in-medium ladder diagrams to all orders is extended by considering the effective range correction in the s-wave interaction and a (spin-independent) p-wave contact-interaction. A two-component recursion generates the in-medium T-matrix at any order when off-shell terms spoil the factorization of multi-loop diagrams. The resummation to all orders is achieved in the form of a geometrical series for the particle-particle ladders, and through an arctangent-function for the combined particle-particle and hole-hole ladders. One finds that the effective range correction changes the results in the limit of large scattering length considerably, with the effect that the Bertsch parameter ? n nearly doubles. Applications to the equation of state of neutron matter at low density are also discussed. For the p-wave contact-interaction the resummation to all orders is facilitated by decomposing tensorial loop-integrals with a transversal and a longitudinal projector. The enhanced attraction provided by the p-wave ladder series has its origin mainly in the coherent sum of Hartree and Fock contributions.

Kaiser, N.

2012-10-01

405

Resummation of in-medium ladder diagrams: s-wave effective range and p-wave interaction  

International Nuclear Information System (INIS)

A recent work on the resummation of fermionic in-medium ladder diagrams to all orders is extended by considering the effective range correction in the s-wave interaction and a (spin-independent) p-wave contact-interaction. A two-component recursion generates the in-medium T-matrix at any order when off-shell terms spoil the factorization of multi-loop diagrams. The resummation to all orders is achieved in the form of a geometrical series for the particle-particle ladders, and through an arctangent-function for the combined particle-particle and hole-hole ladders. One finds that the effective range correction changes the results in the limit of large scattering length considerably, with the effect that the Bertsch parameter ? n nearly doubles. Applications to the equation of state of neutron matter at low density are also discussed. For the p-wave contact-interaction the resummation to all orders is facilitated by decomposing tensorial loop-integrals with a transversal and a longitudinal projector. The enhanced attraction provided by the p-wave ladder series has its origin mainly in the coherent sum of Hartree and Fock contributions. (orig.)

406

To Reach the First Rung and Higher: Building Healthcare Career Ladder Opportunities for Low-Skilled, Disadvantaged Adults  

Science.gov (United States)

This paper is based on various Council for Advancement of Adult Literacy (CAAL) activities including in-depth review of six exemplary career ladder programs offered in various institutional settings: a union, a hospital, a community-based organization (CBO), and three community colleges in partnership with an array of medical centers. The programs…

Chisman, Forrest P.; Spangenberg, Gail

2005-01-01

407

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

CERN Document Server

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.

Gadjiev, S A

2001-01-01

408

Jacob's ladders and the multiplicative asymptotic formula for short and microscopic parts of the Hardy-Littlewood integral  

CERN Document Server

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

Moser, Jan

2009-01-01

409

Charge density wave in the spin ladder of Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$  

CERN Document Server

We consider a multiband charge transfer model for a single spin ladder describing the holes in Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$. Using Hartree-Fock approximation we show how the charge density wave, with its periodicity dependent on doping as recently observed in the experiment, can be stabilized by purely electronic many-body interactions.

Wohlfeld, K; Sawatzky, G A; Wohlfeld, Krzysztof; Oles, Andrzej M.; Sawatzky, George A.

2006-01-01

410

Charge density wave in the spin ladder of Sr14-xCaxCu24O41  

International Nuclear Information System (INIS)

We consider a multiband charge transfer model for a single spin ladder describing the holes in Sr14-xCaxCu24O41. Using Hartree-Fock approximation we show how the charge density wave, with its periodicity dependent on doping as recently observed in the experiment, can be stabilized by purely electronic many-body interactions

411

Teachers' Career Ladder Policy in Ethiopia: An Opportunity for Professional Growth or ''a Stick Disguised as a Carrot?''  

Science.gov (United States)

In response to the ever-declining status of the teaching profession, and its adverse effects on the country's educational system, the Federal Ministry of Education in Ethiopia introduced a policy of the teachers' career ladder in 1994. While reformers believe that the introduction of the policy has improved the condition of the teaching…

Tekleselassie, Abebayehu A.

2005-01-01

412

Attitudinal determinants of fish consumption in Spain and Poland  

DEFF Research Database (Denmark)

OBJECTIVE: To identify attitudinal determinants of fish consumption in Spain and Poland, and to discuss the potential impact of local healthy eating policies in the observed reported frequency of fish consumption. DESIGN: Repeated survey analysis , multivariate linear regression analysis. Data collected through a questionnaire that included socio-demographics, self-reported anthropometrics, as well as validated items of attitudinal and involvement scales, validated items of knowledge about fish, and behaviours (reported fish consumption). SETTING: Consumer survey in Poland and Spain, 1800 respondents in 2004 and 1815 respondents in 2008. RESULTS: In Poland, intentions to consume more fish and reported fish consumption increased in the four years period between both surveys, together with objective knowledge regarding fish. In Spain with the exception of subjective knowledge, fish consumption at home and total fish consumption, all attitudinal and involvement scale changes were statistically significant. Multivariate regression revealed that age had a small but significant positive effect in all scales, except for satisfaction with life, fish consumption out of home and subjective health. Satisfaction with life and subjective knowledge were significantly determined by household size. The differences between countries were statistically significant for involvement with health and fish, for intention to eat fish, the general attitudes and objective knowledge regarding fish. CONCLUSIONS: In Poland, a more positive attitude towards fish, and increased levels of knowledge about this product were observed and could partially be attributed to national policy efforts. In Spain, an interesting feature was observed: more people reported choosing fish when eating out in 2008 compared with respondents in 2004. Such a trend suggests that people slowly move towards healthier choices even in the out of home eating.

Perez Cueto Eulert, Federico Jose A; Pieniak, Z

2012-01-01

413

Fat, fish, fish oil and cancer.  

OpenAIRE

There is an ecological association between total and animal fat consumption and colorectal and breast cancer risk. Mortality data for breast and colorectal cancer for 24 European countries correlated, as expected, with the consumption of animal, but not vegetable, fat. There was an inverse correlation with fish and fish oil consumption, when expressed as a proportion of total or animal fat, and this correlation was significant for both male and female colorectal cancer and for female breast c...

Caygill, C. P.; Charlett, A.; Hill, M. J.

1996-01-01

414

THE PAN-STARRS 1 PHOTOMETRIC REFERENCE LADDER, RELEASE 12.01  

Energy Technology Data Exchange (ETDEWEB)

As of 2012 January 21, the Pan-STARRS 1 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 five filters, g {sub P1}, r {sub P1}, i {sub P1}, z {sub P1}, y {sub 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 data set. This article describes the PS1 Photometric Ladder, Release 12.01. This is the first of a series of data releases to be generated as the survey coverage increases and the data analysis improves. The Photometric Ladder has rungs every hour in right ascension and at four intervals in declination. We will release updates with increased area coverage (more rungs) from the latest data set until the PS1 survey and the final re-reduction are completed. The currently released catalog presents photometry of {approx}1000 objects per square degree in the rungs of the ladder. Saturation occurs at g {sub P1}, r {sub P1}, i {sub P1} {approx} 13.5; z {sub P1} {approx} 13.0; and y {sub P1} {approx} 12.0. Photometry is provided for stars down to g {sub P1}, r {sub P1}, i {sub P1} {approx} 19.1 in the AB system. This data release depends on the rigid 'Ubercal' photometric calibration using only the photometric nights, with systematic uncertainties of (8.0, 7.0, 9.0, 10.7, 12.4) mmag in (g {sub P1}, r {sub P1}, i {sub P1}, z {sub P1}, y {sub P1}). Areas covered only with lower quality nights are also included, and have been tied to the Ubercal solution via relative photometry; photometric accuracy of the non-photometric regions is lower and should be used with caution.

Magnier, E. A.; Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Flewelling, H. A.; Kaiser, N.; Kudritzki, R.-P.; Morgan, J. S.; Sweeney, W. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Schlafly, E.; Finkbeiner, D.; Juric, M.; Stubbs, C. W. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Price, P. A. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2013-04-01

415

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

Directory of Open Access Journals (Sweden)

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.

Gregory Forth

2012-01-01

416

A ladder of topologically non-trivial non-BPS states  

CERN Document Server

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.

Dorigoni, Daniele

2014-01-01

417

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

Science.gov (United States)

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.

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

2011-10-01

418

Towers and ladders: Infinite parameter symmetries in Kaluza-Klein theories  

International Nuclear Information System (INIS)

We introduce a class of infinite dimensional algebras with a 'generalized loop structure' by considering the global symmetries of the four dimensional Lagrangian obtained by compactifying general relativity coupled to Yang-Mills in six dimensions down to M4xS2. The generalization to arbitrary dimensions is then obvious. We show by explicit construction that such algebras possess an infinite number of finite sub-algebras. Among which, for the six dimensional case, is so(1,3) realized on S2 with vanishing Casimir invariants. This so(1,3) may be interpreted, in accord with a previous conjecture of Salam and Strathdee [Ann. Phys. 141, 316(1982)], as the 'ladder' symmetry for the Kaluza-Klein towers. (author)

419

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

Energy Technology Data Exchange (ETDEWEB)

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} Much-Greater-Than m{sup 2}.

Ablinger, Jakob [Research Institute for Symbolic Computation (RISC), Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz (Austria); Bluemlein, Johannes, E-mail: johannes.bluemlein@desy.de [Deutsches Elektronen-Synchrotron, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Hasselhuhn, Alexander [Deutsches Elektronen-Synchrotron, DESY, Platanenallee 6, D-15738 Zeuthen (Germany); Klein, Sebastian [Research Institut fuer Theoretische Physik E, RWTH Aachen University, D-52056 Aachen (Germany); Schneider, Carsten [Research Institute for Symbolic Computation (RISC), Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz (Austria); Wissbrock, Fabian [Deutsches Elektronen-Synchrotron, DESY, Platanenallee 6, D-15738 Zeuthen (Germany)

2012-11-01

420

Optical properties, electron-phonon coupling, and Raman scattering of vanadium ladder compounds  

CERN Document Server

The electronic structure of two V-based ladder compounds, the quarter-filled NaV$_2$O$_5$ in the symmetric phase and the iso-structural half-filled CaV$_2$O$_5$ is investigated by ab initio calculations. Based on the bandstructure we determine the dielectric tensor $\\epsilon(\\omega)$ of these systems in a wide energy range. The frequencies and eigenvectors of the fully symmetric A$_{g}$ phonon modes and the corresponding electron-phonon and spin-phonon coupling parameters are also calculated from first-principles. We determine the Raman scattering intensities of the A$_g$ phonon modes as a function of polarization and frequency of the exciting light. All results, i.e. shape and magnitude of the dielectric function, phonon frequencies and Raman intensities show very good agreement with available experimental data.

Spitaler, J; Evertz, H G; Ambrosch-Draxl, C

2004-01-01

421

Single hole dynamics in the t-J model on two- and three-leg ladders  

CERN Document Server

The dynamics of a single hole in the t-J model on two- (2LL) and three- (3LL) leg ladders is studied using a recently developed quantum Monte Carlo algorithm. For the 2LL it is shown that in addition to the most pronounced features of the spectral function, well described by the limit of strong coupling along the rungs, a clear shadow band appears in the antibonding channel. Moreover, both the bonding band and its shadow have a finite quasiparticle (QP) weight in the thermodynamic limit. For strong coupling along the rungs of the 3LL, the low-energy spectrum in the antisymmetric channel is similar to a one-dimensional chain, whereas in the two symmetric channels it resembles the 2LL. The QP weight vanishes in the antisymmetric channel, but is finite in the symmetric one.

Brunner, M; Assaad, F F; Muramatsu, A; Brunner, Michael; Capponi, Sylvain; Assaad, Fakher F.; Muramatsu, Alejandro

2001-01-01

422

Ladder to Success – Eliciting Project Managers’ Perceptions of IS Project Success Criteria  

Directory of Open Access Journals (Sweden)

Full Text Available The traditional approach to assess information system (IS project success is adherence to planning (ATP – meeting budget, schedule, and requirements targets. Today, scholars agree that ATP is insufficient to adequately assess IS project success, but an agreed-on set of success criteria is still missing. Many works on this topic are based on theoretical considerations rather than empirical inquiries. We analyze practitioners’ subjective perspectives by investigating what criteria IS project managers consider relevant for IS project success assessment. We interview eleven experienced project managers in Germany, applying Repertory Grid and Laddering to minimize potential biases. Our results yield eight success criteria, indicating that criteria like process efficiency and stakeholder satisfaction must be considered in addition to ATP. Scholars can use our findings to apply the identified success criteria in future studies. Practitioners gain insights into the expert perspective on project success and might rethink the way of assessing success in their projects.

Oleg Pankratz

2014-01-01

423

NMR study of spin ladder compound (CPA)2CuBr4  

International Nuclear Information System (INIS)

We performed a nuclear magnetic resonance experiment on 1H in (CPA)2CuBr4 (CPA=cyclopentylammonium) which is considered as two-leg spin ladder system antiferromagnetic compound. Applied field range up to 8.7T covers the critical field Hc (=1.7T) where the energy gap disappears. In the field range Hc, the nuclear spin-lattice relaxation rate T1-1 showed a thermal activation-type behavior, reflecting the presence of the finite spin gap at low temperature. As increasing the magnetic field across the Hc, the temperature dependence of T1-1 gradually changed from the thermal activation-type to the power-law type in the temperature range between 5 and 2K. Further, we found a maximum of T1-1 around 2K for H>Hc

424

Amorphous SiC xO y coatings from ladder-like polysilsesquioxanes  

Science.gov (United States)

Pyrolysis of polysiloxane and/or polysilsesquioxane polymers is a very promising method for advanced ceramics processing. Xerogels obtained by polycondensation of siloxanes containing methyl groups bonded to silicon atoms are precursors in this method. The ratio of Si-O and Si-C bonds depends on the type of xerogel. In the presented work the xerogel materials of ladder-like structure were studied. Pyrolysis was carried out for several hours in argon (absolutely free from oxygen) at 800 °C. The glassy SiC xO y ceramics (black glass) with intrinsic homogeneity on the atomic level were obtained. The formation of black glasses was confirmed by MIR and MAS NMR spectroscopy.

Handke, M.; Sitarz, M.; D?ugo?, E.

2011-05-01

425

Commentary on rainbow-ladder truncation for excited states and exotics  

CERN Document Server

Ground-state, radially-excited and exotic scalar-, vector- and flavoured-pseudoscalar-mesons are studied in rainbow-ladder truncation using an interaction kernel that is consonant with modern DSE- and lattice-QCD results. The inability of this truncation to provide realistic predictions for the masses of excited- and exotic-states is confirmed and explained. On the other hand, its application does provide information that is potentially useful in proceeding beyond this leading-order truncation, e.g.: assisting with development of projection techniques that ease the computation of excited state properties; placing qualitative constraints on the long-range behaviour of the interaction kernel; and highlighting and illustrating some features of hadron observables that do not depend on details of the dynamics.

Qin, Si-xue; Liu, Yu-xin; Roberts, Craig D; Wilson, David J

2011-01-01

426

Inelastic quantum transport in a ladder model: application to DNA conduction  

CERN Document Server

We investigate quantum transport characteristics of a ladder model, which effectively mimics the topology of a double-stranded DNA molecule. We consider the interaction of tunneling charges with a selected internal vibrational degree of freedom and discuss its influence on the structure of the current-voltage characteristics. Further, molecule-electrode contact effects are shown to dramatically affect the orders of magnitude of the current. Recent electrical transport measurements on suspended DNA oligomers with a complex base-pair sequence, revealing strikingly high currents, are also presented and used as a reference point for the theoretical modeling. A semi-quantitative description of the measured I-V curves is achieved, suggesting that the coupling to vibrational excitations plays an important role in DNA conduction.

Gutíerrez, R; Cohen, H; Porath, D; Cuniberti, G

2006-01-01

427

Ultraslow Optical Solitons and Their Storage and Retrieval in an Ultracold Ladder-Type Atomic System  

CERN Document Server

We propose a scheme to obtain stable nonlinear optical pulses and realize their storage and retrieval in an ultracold ladder-type three-level atomic gas via electromagnetically induced transparency. Based on Maxwell-Bloch equations we derive a nonlinear equation governing the evolution of probe field envelope, and show that optical solitons with ultraslow propagating velocity and extremely low generation power can be created in the system. Furthermore, we demonstrate that such ultraslow optical solitons can be stored and retrieved by switching off and on a control field. Due to the balance between dispersion and nonlinearity, the ultraslow optical solitons are robust during propagation, and hence their storage and retrieval are more desirable than that of linear optical pulses. This raises the possibility of realizing the storage and retrieval of light and quantum information by using solitonic pulses.

Chen, Yang; Huang, Guoxiang

2014-01-01

428

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.

429

The local-ladder effect: social status and subjective well-being.  

Science.gov (United States)

Dozens of studies in different nations have revealed that socioeconomic status only weakly predicts an individual's subjective well-being (SWB). These results imply that although the pursuit of social status is a fundamental human motivation, achieving high status has little impact on one's SWB. However, we propose that sociometric status-the respect and admiration one has in face-to-face groups (e.g., among friends or coworkers)-has a stronger effect on SWB than does socioeconomic status. Using correlational, experimental, and longitudinal methodologies, four studies found consistent evidence for a local-ladder effect: Sociometric status significantly predicted satisfaction with life and the experience of positive and negative emotions. Longitudinally, as sociometric status rose or fell, SWB rose or fell accordingly. Furthermore, these effects were driven by feelings of power and social acceptance. Overall, individuals' sociometric status matters more to their SWB than does their socioeconomic status. PMID:22653798

Anderson, Cameron; Kraus, Michael W; Galinsky, Adam D; Keltner, Dacher

2012-07-01

430

Three-loop master integrals for ladder-box diagrams with one massive leg  

CERN Document Server

The three-loop master integrals for ladder-box diagrams with one massive leg are computed from an eighty-five by eighty-five system of differential equations, solved by means of Magnus exponential. The results of the considered box-type integrals, as well as of the tower of vertex- and bubble-type master integrals associated to subtopologies, are given as a Taylor series expansion in the dimensional regulator parameter epsilon = (4-d)/2. The coefficients of the series are expressed in terms of uniform weight combinations of multiple polylogarithms and transcendental constants up to weight six. The considered integrals enter the next-to-next-to-next-to-leading order virtual corrections to scattering processes like the three-jet production mediated by vector boson decay, V* -> jjj, as well as the Higgs plus one-jet production in gluon fusion, pp -> Hj.

Di Vita, Stefano; Schubert, Ulrich; Yundin, Valery

2014-01-01

431

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

432

Reappraisal of the traditional Wenckebach phenomenon with a modified ladder diagram.  

Science.gov (United States)

Understanding of the traditional Wenckebach phenomenon is enhanced by using a modified ladder diagram where AV conduction in any cycle is represented by a slanted line in the AV bar together with similar AV conduction lines of all the preceding cycles. The diagram facilitates calculation of the duration of RR intervals (equal to the basic PP or sinus interval minus the PR or AV increment applied to this particular cycle) and the duration of the pause (equal to 2 × PP or sinus interval minus the sum of all the increments applied to the AV delay). The modified Wenckebach diagram should help students understand the mysterious clustering of QRS complexes or "paradoxical" increase of the ventricular rate that occurs during a Wenckebach sequence. PMID:22276622

Barold, S Serge; Stroobandt, Roland X; Sinnaeve, Alfons F; Andries, E; Herweg, Bengt

2012-01-01

433

A ladder of topologically non-trivial non-BPS states  

Science.gov (United States)

We consider a simple quiver gauge theory with gauge group U(r1) × U(r2) and a Higgs field in the bi-fundamental representation. The background for this theory is a compact Kähler 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.

Dorigoni, Daniele; Rink, Norman A.

2014-12-01

434

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)

435

Ultraslow optical solitons and their storage and retrieval in an ultracold ladder-type atomic system  

Science.gov (United States)

We propose a scheme to obtain stable nonlinear optical pulses and realize their storage and retrieval in an ultracold ladder-type three-level atomic gas via electromagnetically induced transparency. Based on Maxwell-Bloch equations we derive a nonlinear equation governing the evolution of the probe-field envelope and show that optical solitons with an ultraslow propagating velocity and extremely low generation power can be created in the system. Furthermore, we demonstrate that such ultraslow optical solitons can be stored and retrieved by switching a control field off and on. Due to the balance between dispersion and nonlinearity, the ultraslow optical solitons are robust during propagation, and hence their storage and retrieval are more desirable than those of linear optical pulses. This raises the possibility of realizing the storage and retrieval of light and quantum information by using solitonic pulses.

Chen, Yang; Bai, Zhengyang; Huang, Guoxiang

2014-02-01

436

Gadolinium(III)-hydroxy ladders trapped in succinate frameworks with optimized magnetocaloric effect.  

Science.gov (United States)

Two kinds of inorganic gadolinium(III)-hydroxy "ladders", [2×n] and [3×n], were successfully trapped in succinate (suc) coordination polymers, [Gd2(OH)2(suc)2(H2O)]n·2nH2O (1) and [Gd6(OH)8(suc)5(H2O)2 ]n·4n H2O (2), respectively. Such coordination polymers could be regarded as alternating inorganic-organic hybrid materials with relatively high density. Magnetic and heat capacity studies reveal a large cryogenic magnetocaloric effect (MCE) in both compounds, namely (?H=70 kG) 42.8 J kg(-1) K(-1) for complex 1 and 48.0 J kg(-1) K(-1) for complex 2. The effect of the high density is evident, which gives very large volumetric MCEs up to 120 and 144 mJ cm(-3) K(-1) for complexes 1 and 2, respectively. PMID:23959529

Chen, Yan-Cong; Guo, Fu-Sheng; Zheng, Yan-Zhen; Liu, Jun-Liang; Leng, Ji-Dong; Tarasenko, Róbert; Orendá?, Martin; Prokleška, Jan; Sechovský, Vladimír; Tong, Ming-Liang

2013-09-27

437

Fish and wildlife surveillance  

Energy Technology Data Exchange (ETDEWEB)

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.

Poston, T.M.

1995-06-01

438

Combating Illegal Fishing  

OpenAIRE

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 agains...

Sorin Stanciu; Andrea Feher

2010-01-01

439

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

440

Neutron scattering evidence for isolated spin-1/2 ladders in (C$_5$D$_{12}$N)$_2$CuBr$_4$  

OpenAIRE

Inelastic neutron scattering was used to determine the spin Hamiltonian for the singlet ground state system of fully deuterated BPCB, (C$_{5}$D$_{12}$N)$_{2}$CuBr$_{4}$. A 2-leg spin-1/2 ladder model, with $J_\\bot = (1.09 \\pm 0.01)$ meV and $J_\\| = (0.296 \\pm 0.005)$ meV, accurately describes the data. The experimental limit on the effective inter-ladder exchange constant is $|J_{\\rm int}^{\\rm eff}|\\lesssim 0.006$ meV, and the limit on total diagonal, intra-ladder exchange i...

Savici, A. T.; Granroth, G. E.; Broholm, C. L.; Pajerowski, D. M.; Brown, C. M.; Talham, D. R.; Meisel, M. W.; Schmidt, K. P.; Uhrig, G. S.; Nagler, S. E.

2009-01-01

441

Proton NMR study of a random-bond ladder Cu2(C5H12N2)2(Cl1-xBrx)4  

International Nuclear Information System (INIS)

Proton NMR measurements have been performed to investigate random-bond effects in a spin-ladder system. We synthesized a random-bond ladder Cu2(C5H12N2)2(Cl1-xBrx)4 and measured the temperature dependence of 1H spin-lattice relaxation time. The spin-gap energy for a random mixture compound is smaller than those for pure systems. The result suggests that the ground state of the random-bond ladder approaches to a gapless state

442

Vibrational excitation of molecules by chirped laser radiation in ladder-climbing and autoresonance regimes  

International Nuclear Information System (INIS)

Full Text:Vibrational excitation of molecules or dissociation without ionization is of great importance for initiation and improved efficiency of certain chemical reactions. Therefore, since the emergence of lasers, a long standing goal seas to excite and control molecular dissociation or molecular vibrations by laser radiation. Direct excitation of high vibrational levels in a molecule by a monochromatic radiation is inefficient, due to the small value of the transition dipole moment between the initial and final states. An alternative is to create a cascading transition from the initial to the final state through a series of intermediate levels by using a chirped light pulse having a continuously varying frequency. This method is usually referred to as a vibrational ladder climbing (LC). The dynamic autoresonance (AR) is a method to excite a classical oscillatory, nonlinear system to high energies and control the excited state by changing the driving frequency. This method is general and has been applied in many fields of physics. It has been identified that in both the AR and the LC, the external driving force (due to the laser radiation) should exceed some threshold in order to excite the nonlinear system efficiently. This threshold is in general a function of the chirp rate and the physical properties of the system, such as the dipole moment and the nonlinearity coefficient. Here we will discuss the similarities and differences between the LC and the AR regimes. rences between the LC and the AR regimes. We shall introduce two parameters P1 and P2, fully characterizing the domains of ladder-climbing and autoresonance in the parameter space. We will show that there is a smooth transition from the LC to the AR regions in the P1-P2 plane. Finally, we shall describe an experiment conducted in our laboratory to demonstrate these methods in application to Hydrogen-fluoride molecules

443

Anglers' fishing problem  

CERN Document Server

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