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

OpenAIRE

Utilization of the fish ladder installed at the Engenheiro Sergio Motta Dam (also known as Porto Primavera) on the Paraná River, Southern Brazil, by long-distance migrating potamodromous species (sampling Protocol I), and ascending and descending movements (Protocol II) were evaluated. Three pools along the fish ladder (designated as lower, middle, and upper) were sampled monthly between December, 2004 and March, 2005 to determine the abundance of species in the ladder. The ascending and des...

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

2007-01-01

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Fish ladders: safe fish passage or hotspot for predation?  

Scientific Electronic Library Online (English)

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

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

2012-10-01

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

International Nuclear Information System (INIS)

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

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

Directory of Open Access Journals (Sweden)

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

Domingo Rodriguez Fernandez

2004-08-01

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

Scientific Electronic Library Online (English)

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

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

2004-08-01

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

Directory of Open Access Journals (Sweden)

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

Sérgio Makrakis

2007-01-01

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Fish-ladders - future and new projects for prepared small HPP  

International Nuclear Information System (INIS)

During a long term preparation of the small HPP, the demonstration of our highest environmental tolerance is to propose the most suitable technical installation, so called the fish ladder in order to overcome barrier of intake structure in accordance with the needs and requires. (author)

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Changes in selection and evolutionary responses in migratory brown trout following the construction of a fish ladder  

OpenAIRE

Brown trout (Salmo trutta) are extensively harvested and its habitat highly influenced by human encroachments. Using a 40-year time series of mark–recapture data we estimate vital rates for a piscivorous trout population. This population spawns upstream of a waterfall, which historically acted as a migration barrier for smaller trout. In 1966, the waterfall was dammed and a fish ladder constructed. All fish ascending the fish ladder were individually tagged and measured for a variety of tra...

Haugen, Thrond Oddvar; Aass, Per; Stenseth, Nils Christian; Vøllestad, Leif Asbjørn

2008-01-01

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

Directory of Open Access Journals (Sweden)

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

Angelo Antônio Agostinho

2007-01-01

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Movements through a fish ladder: temporal patterns and motivations to move upstream  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Os mecanismos de transposição de peixes em barragens visam restabelecer a conectividade entre habitats críticos à manutenção para as espécies que tenham uma ampla área de vida. Os movimentos ascendentes da maioria das espécies migradoras conhecidas são realizados por motivação reprodutiva (adultos) [...] ou dispersiva (juvenis). Neste contexto, o presente estudo tem como objetivo avaliar se existe um padrão temporal na abundância de peixes a jusante da barragem e na escada da UHE Lajeado (UHE Luis Eduardo Magalhães, rio Tocantins) que segue a sazonalidade reprodutiva. Adicionalmente, busca avaliar se reprodução é a motivação predominante dos cardumes que ascendem a escada. Para isto, as amostragens foram realizadas mensalmente de novembro de 2002 a outubro de 2003 a jusante da barragem, com o uso de redes de espera, e nos tanques de descanso da escada, com tarrafas. A análise da sazonalidade na agregação dos cardumes foi baseada nas variações temporais de abundância e riqueza de espécies, enquanto a motivação reprodutiva para a ascensão foi inferida a partir da freqüência dos estádios de maturação gonadal. Entretanto, durante todo o período foi constatada uma elevada freqüência de indivíduos com gônadas em fase pré-vitelogênica em todas as espécies analisadas, tanto a jusante da barragem (97%) como na escada (98%), sugerindo a inexistência de motivação reprodutiva para a agregação dos peixes a jusante e seus ingressos na escada. Por outro lado, o fato destes estádios dominarem as capturas também a jusante sugere que os locais de desova estão distantes, e que os deslocamentos ascendentes ocorrem por outras razões, como dispersão natural e busca de habitats mais apropriados para alimentação e crescimento. Assim, o ingresso na escada decorreu mais do comportamento reofílico, exacerbado nas espécies migradoras, que de uma motivação endógena ligada à migração reprodutiva. Abstract in english Fish passages are constructed with the aim of reestablishing connectivity between critical habitats, in order to sustain those species that move over a large area during their lives. The upstream movements of most of the known migratory species are made for purposes of reproduction (adults) or dispe [...] rsal (juveniles). The present study was conducted at the ladder constructed at Lajeado Dam (Luis Eduardo Magalhães Hydroelectric Power), on the Tocantins River. The objective was to assess whether there is a temporal pattern in the abundance of fish below the dam and in the ladder, that correlates with their breeding seasons. Additionally, it was examined whether reproduction is the predominant motivation of the shoals of fish that ascend the ladder. Samples were taken monthly from November, 2002 through October, 2003, downriver from the dam with gillnets, and in the resting pools of the fish ladder with cast nets. The analysis of seasonality in the aggregation of the shoals was based on the temporal variations in abundance and species richness. The possibility of a reproductive motivation for ascending the ladder was inferred from the frequency of the stages of gonadal development. However, during the entire study period we observed a high frequency of individuals with gonads in the pre-vitellogenic stage for all analyzed species, both downriver from the dam (97%) and in the fish ladder (98%). These findings suggest that there was no reproductive motivation for the aggregation of the fish downstream and for their entry into the ladder. On the other hand, the dominance of these stages downriver suggests that the spawning habitats are distant, and that the upstream movements occur for other reasons such as dispersal and search for more appropriate habitats for feeding and growth. The entrance into the ladder resulted more from rheophilic behavior, which is more pronounced in migratory species, than from an endogenous motivation linked to reproductive migration.

Carlos Sérgio, Agostinho; Celiana Ribeiro, Pereira; Rafael José de, Oliveira; Iriene Siqueira, Freitas; Elineide Eugênio, Marques.

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

Scientific Electronic Library Online (English)

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

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

2012-10-01

16

Design of Dual Bandpass and Bandreject LC Ladder Filters  

Directory of Open Access Journals (Sweden)

Full Text Available This paper deals with the design of two-passband bandpass and two-stopband bandreject LC ladder filters. The design method is based on the special dual frequency transformation that transforms normalized lowpass to either bandpass with two passbands or to bandreject with two stopbands that are specified by four cutoff frequencies. The paper shows analytical solution relating these four cutoff frequencies to parameters of dual frequency transformation. It enables a direct computation of dual band LC filter elements from a normalized lowpass filter by means of simple relations. These relations have been implemented in the mathematical program Maple (TM as new user functions. They are supposed to be used as an enhancement of Syntfil package which is intended for analog filter design in program Maple. Specific application is shown on an example of the two-passband bandpass LC filter design.

J. Hospodka

2006-09-01

17

Design study of a high frequency proton ladder RFQ  

International Nuclear Information System (INIS)

For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. In the low energy section, between the Ion Source and the main linac an RFQ has to be designed. Accelerating protons from 95 keV to 3.0 MeV the RFQ will oscillate at 325 MHz. This particular high frequency for an RFQ creates difficulties which are challenging in developing this cavity. In order to define a satisfactory geometrical configuration for this resonator, both from the RF and the mechanical point of view, different designs have been examined and compared. Very promising results have been reached with an ladder type RFQ, especially concerning the dipole component of the accelerating fields, which is almost not noticeable. This paper shows 3D simulations of the general layout and a whole cavity demonstrating the power of a ladder type RFQ. It outlines a possible layout for the RFQ within the new FAIR proton injector.

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

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

19

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

20

A career ladder program designed by perioperative staff nurses.  

Science.gov (United States)

Staff members at Baylor University Medical Center, Dallas, were dissatisfied with the existing clinical ladder program, so a committee of perioperative staff nurses was appointed to create a new program. The new program was based on a literature review and RN and management survey data. Under the new program, nurses must accumulate points to quality for or maintain clinical nurse levels I, II, or III. The point system recognizes many professional contributions that were ignored by the previous program. PMID:8534079

Day, D S; Scidmore, C

1995-11-01

21

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

Scientific Electronic Library Online (English)

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

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

22

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

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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  

OpenAIRE

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

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

2012-01-01

24

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.

25

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

Science.gov (United States)

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

Peterson, Ken; And Others

26

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

CERN Document Server

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

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

2007-01-01

27

Pelton Ladder Master Plan.  

Energy Technology Data Exchange (ETDEWEB)

Rearing additional fish in Pelton Ladder provides fishery managers with a low-cost alternative to making major financial investments in new formal hatchery facilities. Adult chinook returning from this rearing program will help bolster the dwindling runs of upriver spring chinook, thus assisting the Council's goal for increased production of this species. The Deschutes River Subbasin Plan envisions need for additional return of hatchery-produced spring chinook in order to meet goals for increased harvest opportunity. Spring chinook released from Pelton Ladder will contribute little to offshore fisheries, as we can account for only about 1 percent of the RBH contribution in offshore fisheries. Based on past performance, we expect 6 percent of the adults produced will be caught in sport, commercial, and tribal subsistence fisheries in the Columbia River. Most benefits of the extra adults produced will be realized in the Deschutes River in the form of increased sport and tribal harvests and increased returns to RBH. Adults collected at Pelton Ladder above production needs will be provided to the CTWS. Return of more adults to the Deschutes River will continue the trend of increased abundance of spring chinook noted since 1985. Rearing of fish in the ladder under the proposed program will provide ODFW and CTWS co-management opportunity, and the associated monitoring and evaluation studies will refine ODFW's ability to effectively manage the RBWPelton Ladder rearing program and will provide inferences about the ability to further employ the fish-rearing potential of unused sections of the fish ladder.

Smith, Max

1991-07-01

28

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

29

29 CFR 1910.27 - Fixed ladders.  

Science.gov (United States)

...2010-07-01 2010-07-01 false Fixed ladders. 1910.27 Section 1910...Walking-Working Surfaces § 1910.27 Fixed ladders. (a) Design requirements...specified in § 1910.25. All wood parts of fixed ladders shall meet the requirements...

2010-07-01

30

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

Directory of Open Access Journals (Sweden)

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

Saidijam M

2011-05-01

31

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

Scientific Electronic Library Online (English)

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

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

2014-01-01

32

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

33

Understanding the Behaviour of Infinite Ladder Circuits  

Science.gov (United States)

Infinite ladder circuits are often encountered in undergraduate electrical engineering and physics curricula when dealing with series and parallel combination of impedances, as a part of filter design or wave propagation on transmission lines. The input impedance of such infinite ladder circuits is derived by assuming that the input impedance does…

Ucak, C.; Yegin, K.

2008-01-01

34

The Career Ladder Program in Tennessee.  

Science.gov (United States)

The Career Ladder Program in Tennessee is a comprehensive teacher evaluation and certification system. The program is designed to attract, retain, and reward excellent teachers. On the basis of performance evaluation, teachers can move up a Career Ladder which provides monetary incentives and allows teachers professional growth opportunities…

Furtwengler, Carol; And Others

35

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

36

Materials design principles of ancient fish armour  

Science.gov (United States)

Knowledge of the structure-property-function relationships of dermal scales of armoured fish could enable pathways to improved bioinspired human body armour, and may provide clues to the evolutionary origins of mineralized tissues. Here, we present a multiscale experimental and computational approach that reveals the materials design principles present within individual ganoid scales from the `living fossil' Polypterus senegalus. This fish belongs to the ancient family Polypteridae, which first appeared 96 million years ago during the Cretaceous period and still retains many of their characteristics. The mechanistic origins of penetration resistance (approximating a biting attack) were investigated and found to include the juxtaposition of multiple distinct reinforcing composite layers that each undergo their own unique deformation mechanisms, a unique spatial functional form of mechanical properties with regions of differing levels of gradation within and between material layers, and layers with an undetectable gradation, load-dependent effective material properties, circumferential surface cracking, orthogonal microcracking in laminated sublayers and geometrically corrugated junctions between layers.

Bruet, Benjamin J. F.; Song, Juha; Boyce, Mary C.; Ortiz, Christine

2008-09-01

37

A career ladder for radiological technologists.  

Science.gov (United States)

A career ladder is a mechanism for employee progression within a chosen field. This paper describes the design and implementation of such a system in a large community radiology department. The career ladder system included integrated job descriptions, salary scales and evaluation procedures for radiology technologists. The implementation of this new system had a positive effect on employee morale manifested in decreased turnover, less absenteeism and increased job satisfaction. PMID:10265983

Gillan, G D; Pearce, J; Rutherford, M; Walters, L

1984-03-01

38

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.

39

Ladder attachment platform  

Science.gov (United States)

A ladder attachment platform is provided that includes a base for attachment to a ladder that has first and second side rails and a plurality of rungs that extend between in a lateral direction. Also included is a user platform for having a user stand thereon that is carried by the base. The user platform may be positioned with respect to the ladder so that it is not located between a first plane that extends through the first side rail and is perpendicular to the lateral direction and a second plane that extends through the second side rail and is perpendicular to the lateral direction.

Swygert,; Richard, W [Springfield, SC

2012-08-28

40

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

CERN Document Server

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

Blocki, J

2001-01-01

41

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

42

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

43

Career ladder program.  

Science.gov (United States)

In June 1990, Santa Rosa Children's Hospital instituted a multitrack career ladder program for registered nurses, in response to the issues of retention of expert nursing staff and development of professional nursing practice. The program incorporates clinical, education, and management tracks, providing vertical and lateral mobility to the registered nurse. Performance evaluation criteria complement the promotional process, and the registered nurse has a menu of requirements to fulfill each year upon promotion to or maintenance of career ladder level. Through incorporation of a graduated salary system, the program has been a retention bonus for registered nurses at Santa Rosa Children's Hospital. In addition, the career ladder program has been very successful in promoting professional nursing practice within the hospital. PMID:8418098

Guerrero, J H; Hansen, M L

1993-01-01

44

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

45

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

46

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

47

Baryons and ladders  

International Nuclear Information System (INIS)

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

48

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

49

Evaluation of a career ladder program in an ambulatory care environment.  

Science.gov (United States)

Clinical ladders, or career advancement systems, were designed to enhance professional development, provide a reward system for quality clinical performance, promote quality nursing practice, and improve job satisfaction among nurses. Most of the literature on RN clinical ladder programs is related to the acute care setting, where these programs originated; not much is known about their effectiveness in the ambulatory care environment. The RN Career Ladder at Kaiser Permanente of Colorado was begun by a Labor Management Partnership Committee in 2003, and awards financial incentives to RNs who demonstrate a commitment to continuing education, leadership activities, and program development on a local and regional level. In this study significantly more involvement in leadership, interdisciplinary, and quality improvement activities were found among career ladder nurses than non-career ladder nurses, regardless of their job role. It is not clear whether nursing leaders gravitate toward a career ladder or whether career ladder participation encourages increased participation in leadership activities. PMID:19330969

Nelson, Joan M; Cook, Paul F

2008-01-01

50

Administrator/Supervisor Career Ladder Orientation Manual, 1985-86. Tennessee Career Ladder Better Schools Program.  

Science.gov (United States)

This manual is designed to provide Tennessee School administrators and supervisors with the information needed to understand the revised Career Ladder Evaluation System, and prepare them for the evaluation at Career Levels I and II. The manual covers the following information: (1) improvements of the revised system; (2) assumptions and principles;…

Tennessee State Dept. of Education, Nashville.

51

Design and construction of an Electric Fish Finder  

Directory of Open Access Journals (Sweden)

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

William G. R. Crampton

2007-09-01

52

Design and construction of an Electric Fish Finder  

Scientific Electronic Library Online (English)

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

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

2007-09-01

53

fish  

Science.gov (United States)

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

cory jones

2009-09-28

54

Undergraduate design projects for assistive technology needs: assisted fishing.  

Science.gov (United States)

In 2010 the University of Wyoming, College of Engineering and Applied Science was funded for a five year increment of the National Science Foundation?s Research to Aid Persons with Disabilities. This program provides a vital link between challenged individuals who require custom assistive technology devices with senior capstone design students who require challenging, meaningful projects. The program also provides education for our next generation of engineers on the needs of all individuals. In this paper we describe the program organization including project partners in the College and Wyoming Institute for Disabilities (WIND). We also provide a case study of a recently completed project for an assistive fishing device. PMID:22846261

Borrego, Nick; Bilan, Kristi; Gebes, T J; Barrett, S F; Morton, S A

2012-01-01

55

Pharmacist career ladder with clinical privilege categories.  

Science.gov (United States)

The development of a career ladder program for staff pharmacists at a Department of Veterans Affairs (VA) medical center is recounted. Center policy required the establishment of clinical privileges for all pharmacists with direct patient contact and specified three VA privilege categories with increasing degrees of autonomy. The pharmacy department supported the need for all pharmacists to incorporate clinical activities into their daily practice but faced several problems, including inadequate instruction, insufficient incentives, fragmentation of clinical services, and subjectivity of measures of competence. In response, a pharmacy credentialing committee created a career ladder with three levels based on the established system of clinical privileges. Level A integrated basic clinical pharmacy knowledge with dispensing activities. Level B increased the number of clinical skills required and allowed the pharmacist to act as a therapeutic consultant. Level C incorporated the skills necessary for specialty practice. Instructors were designated for each clinical service area, readings and sample problems were assigned, and staff development presentations were improved. Objective tests of skills were designed. Combining the three levels on the career ladder with the three categories of clinical privileges formed a matrix of nine options for advancement. Pharmacists applying for advancement must master all requisite skills and submit relevant documentation. Each level carries a pay increase of 2%. A total of 53% of the staff pharmacists have participated in the program, which has had a favorable impact on staff retention. By combining nationally established categories of clinical privileges with an institution-specific career ladder, a pharmacy department helped ensure the consistency of services and promote the development of clinical practitioners. PMID:1928140

Swanson, K M; Hunter, W B; Trask, S J; Beck, S M

1991-09-01

56

FPGA Implementations of Ladder Diagrams  

OpenAIRE

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 explore...

Neil William Bergmann; Peter Waldeck; Shukla, Sunil K.

2013-01-01

57

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,

58

Generalized antiferromagnetic Heisenberg spin ladders  

Science.gov (United States)

We utilize the path-integral technique to derive the non-linear Sigma model (NL?M) for generalized antiferromagnetic spin-ladder systems on the square lattice with diagonal (next-nearest neighbor) interactions in addition to the nearest neighbor interaction. The model Hamiltonian is: H=? a=1n l ? i J aSa(i)· Sa(i+1)+J a,a+1? Sa(i)· Sa+1(i)+K a,a+1Sa(i)· Sa+1(i+1)+M a,a+1Sa(i+1)· Sa(i) . The topological term of the NL?M is absent for the spin- s ladder with an even number of legs and is equal to 2 ?s for the ladder with an odd number of legs. The spin wave velocity is s[? a( Ja- Ma, a+1 - Ka, a+1 )/? b, cLb, c-1] 1/2 where La, b=4 Ja+ Ja, a+1 ?+ Ja, a-1 ?- Ma, a+1 - Ma, a-1 - Ka, a+1 - Ka, a-1 when a= b, and La, b= Ja, b?+ Ka, b+ Ma, b, when | a- b|=1. The spin gaps are predicted for spin ladders with an even number of chains. We also consider a two-leg ladder with spin s˜ and s, in which diagonal interactions occur only in the even (or odd) cells. The Berry phase is found to be dependent on the coupling constants. The expressions of the spin-wave velocity and spin gap are also given for even-leg ladders. The operator approach to the generalized spin-ladder problem is also presented. Finally we address the finite-size NL?M treatment of this system.

Tsai, Yan-Chr; Hu, Chin-Kun

2001-10-01

59

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

60

Semiclassical description of spin ladders  

CERN Document Server

The Heisenberg spin ladder is studied in the semiclassical limit, via a mapping to the nonlinear \\sigma model. Different treatments are needed if the inter-chain coupling K is small, intermediate or large. For intermediate coupling a single nonlinear \\sigma model is used for the ladder. Its predicts a spin gap for all nonzero values of K if the sum s+\\tilde s of the spins of the two chains is an integer, and no gap otherwise. For small K, a better treatment proceeds by coupling two nonlinear sigma models, one for each chain. For integer s=\\tilde s, the saddle-point approximation predicts a sharp drop in the gap as K increases from zero. A Monte-Carlo simulation of a spin 1 ladder is presented which supports the analytical results.

Sénéchal, D

1995-01-01

61

Laddering em pesquisa de marketing Laddering in marketing research  

Directory of Open Access Journals (Sweden)

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

Tânia Modesto Veludo-de-Oliveira

2008-03-01

62

Laddering em pesquisa de marketing / Laddering in marketing research  

Scientific Electronic Library Online (English)

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

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

2008-03-01

63

Design complexity in termite-fishing tools of chimpanzees (Pan troglodytes)  

OpenAIRE

Adopting the approach taken with New Caledonian crows (Corvus moneduloides), we present evidence of design complexity in one of the termite-fishing tools of chimpanzees (Pan troglodytes) in the Goualougo Triangle, Republic of Congo. Prior to termite fishing, chimpanzees applied a set of deliberate, distinguishable actions to modify herb stems to fashion a brush-tipped probe, which is different from the form of fishing tools used by chimpanzees in East and West Africa. This means that ‘brush...

Sanz, Crickette; Call, Josep; Morgan, David

2009-01-01

64

An Ethnography of Career Ladder Planning and Implementation.  

Science.gov (United States)

This paper presents initial findings of a 3-year study of career ladder design and implementation in the Danville (Virginia) school system, focusing on data collected primarily between April 1986 and April 1987, after the first group of candidates was promoted to the rank of career teacher and a second group was undergoing review for similar…

Brandt, Richard M.

65

A regularly spaced and self-revealing protein ladder for anti-tag Western blot analysis.  

Science.gov (United States)

We designed a protein ladder (hereafter referred to as "Mega-tag") that contains 14 of the most commonly used epitope tags fused to molecular weight markers. The Mega-tag ladder can be simultaneously visualized when anti-tag antibodies are used to detect epitope-tagged recombinant proteins in Western blots. The logarithm of molecular weights and relative mobility of the Mega-tag protein ladder are highly correlated (R(2)=0.997±0.00232), indicating that the dye-free Mega-tag protein ladder is accurate. It can also serve as a positive control for anti-epitope tag immunoblots. The Mega-tag protein ladder should provide a convenient and precise tool for Western blot analysis. PMID:22885722

Kao, Chien-Han; Cheng, Chiu-Min; Chuang, Kuo-Hsiang; Chuang, Chih-Hung; Tzou, Shey-Cherng; Cheng, Ta-Chun; Hsieh, Yuan-Chin; Liao, Kuang-Wen; Wang, Yun-Ming; Chang, Long-Sen; Roffler, Steve R; Chen, Fang Ming; Cheng, Tian-Lu

2012-12-01

66

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

67

Shaft door with folding ladder  

International Nuclear Information System (INIS)

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

68

D0 Silicon Upgrade: Thermally Induced Bowing in a 3-CHIP Ladder  

International Nuclear Information System (INIS)

The end of the 3 chip ladder, shown below, consists of silicon mounted on a piece of beryllium which is adhered to the cooling channel. Outboard of the cooling channel is a region of ladder composed primarily of silicon/beryllium. Operation and cooling of the ladder results in a change in temperature from the assembly temperature, which will result in deflections due to the difference in expansion coefficients of the two materials, otherwise known as 'bi-metal' bowing. The goal of this note is to present a design of the beryllium plate on the underside of the ladder which reduces the thermally induced bow to a reasonable deflection. This region of ladder will see a fairly large temperature gradient during detector operation due to the heat load of the transceivers on the ladder end. Expected temperatures range between 22 C on the ladder end to 9.5 C near the cooling channel for a coolant temperature of 5 C. The coolant temperature may be as low as -5 C, so we may estimate a lower limit on the ladder temperatures to be 10 C cooler, ranging from 12 C on the ladder end to -0.5 C near the bulkhead (assumes negligible convection from the ladder surface). With a ladder assembly temperature of 23 C we may estimate the end deflection of the ladder based on the assumed temperatures during operation by applying Roark equation 6a. Equation 6a describes end deflection for a cantilever beam under application of a uniform temperature change. The equation is modified to account for . The equation is modified to account for a uniform temperature gradient along the bi-metal region. The equation is differentiated twice, the assumed temperature dependence is plugged, and the equation is re-integrated twice. deflection = C*?T*L2. The constant C is a function of material thicknesses and moduli. The composite region (beryllium and silicon 'bi-metal' region) is between 21.0 and 25.0 mm in length (the HDI design is still in progress) plus the additional 1.975 mm shown in the ladder drawing below. Hence, the composite region is assumed to extend 27 mm beyond the bulkhead ledge. The silicon extends 4 mm beyond the composite region. Deflection of the ladder end, the silicon, is calculated.

69

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

70

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

71

Correlation potential and ladder diagrams  

CERN Document Server

The all-order correlation potential method of accurate atomic structure calculations for atoms with one external electron is extended to include one more class of correlation diagrams to all orders. These are the so-called ladder diagrams which describe residual Coulomb interaction between an external electron and atomic core. This is in addition to the screening of Coulomb interaction by core electrons and the hole-particle interaction in the core polarization operator which are also included in all orders. Calculations of the energies of the lowest $s$, $p$ and $d$ states of cesium and thallium show that inclusion of the ladder diagrams leads to significant improvement of the accuracy of the calculations. The discrepancy between theoretical and experimental energies is reduced to a small fraction of a per cent in all cases. This widens the range of atoms and atomic states for which the correlation potential method can produce very accurate results.

Dzuba, V A

2008-01-01

72

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

73

Dispersal Patterns of Coastal Fish: Implications for Designing Networks of Marine Protected Areas  

OpenAIRE

Information about dispersal scales of fish at various life history stages is critical for successful design of networks of marine protected areas, but is lacking for most species and regions. Otolith chemistry provides an opportunity to investigate dispersal patterns at a number of life history stages. Our aim was to assess patterns of larval and post-settlement (i.e. between settlement and recruitment) dispersal at two different spatial scales in a Mediterranean coastal fish (i.e. white sea ...

Di Franco, Antonio; Gillanders, Bronwyn M.; Benedetto, Giuseppe; Pennetta, Antonio; Leo, Giulio A.; Guidetti, Paolo

2012-01-01

74

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

75

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

76

Development of Ladder Climbing Robot LCR-1  

International Nuclear Information System (INIS)

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

77

Dilogarithm ladders from Wilson loops  

CERN Document Server

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

Bianchi, Marco S

2014-01-01

78

Design and Implementation of an Electronic Nose System for the Determination of Fish Freshness  

Science.gov (United States)

An electronic nose has been designed to evaluate fish freshness. The e-nose consists of 15 commercial sensors, a home-made data acquisition system and a PC application that communicates with the data acquisition system. The equipment has been conceived so that the sensors can be configured in non-standard operation modes in order to improve the sensors discrimination capabilities.

Masot, Rafael; Alcañiz, Miguel; Pérez-Esteve, Edgar; Barat, José M.; Gil, Luis; Martínez-Máñez, Ramón; Garcia-Breijo, Eduardo

2009-05-01

79

Finned-Ladder Slow-Wave Circuit for a TWT  

Science.gov (United States)

A finned-ladder structure has been invented in an effort to improve the design of the slow-wave circuit of a traveling-wave tube (TWT). The point of departure for the design effort was a prototype TWT that contains a ring-plane slow-wave circuit (see Figure 1). The design effort was a response to the observation that despite the high-power capabilities of the ringplane TWT, its requirement for a high supply voltage and its low bandwidth have made it unacceptable for use outside a laboratory setting.

Wilson, Jeffrey D.; Wintucky, Edwin G.; Kory, Carol L.

2004-01-01

80

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

International Nuclear Information System (INIS)

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

81

Lessons from Tennessee's Career Ladder Program.  

Science.gov (United States)

Discusses evaluation issues that developed during implementation of the nation's first statewide career ladder program in Tennessee. After three years of development major issues have centered around communication, confidentiality, paperwork, career development, multidata source systems, and the evaluation cycle. (CJH)

Furtwengler, Carol B.

1987-01-01

82

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

Directory of Open Access Journals (Sweden)

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

Bikash Sarkar

2013-02-01

83

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1995-09-01

84

Vortex Fractionalization in a Josephson Ladder  

OpenAIRE

We show numerically that, in a Josephson ladder with periodic boundary conditions and subject to a suitable transverse magnetic field, a vortex excitation can spontaneously break up into two or more fractional excitations. If the ladder has N plaquettes, and N is divisible by an integer q, then in an applied transverse field of 1/q flux quanta per plaquette the ground state is a regular pattern of one fluxon every q plaquettes. When one additional fluxon is added to the ladd...

Tornes, Ivan; Stroud, David

2005-01-01

85

Clinical career ladders: Hamot Medical Center.  

Science.gov (United States)

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

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

1989-11-01

86

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

Energy Technology Data Exchange (ETDEWEB)

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

Knapp, Suzanne M.

1993-03-01

87

A ladder curriculum in clinical microbiology.  

Science.gov (United States)

A continuum of four microbiology courses for medical technology majors has been developed by the Medical Laboratory Science Program at Northeastern University. Using a system approach to curriculum design, the academic and clinical faculty identified career-entry capabilities, delineated appropriate subject content, and developed an instructional system which placed individual topics into one of four courses in the ladder curriculum: a basic, second-year, university-based clinical microbiology course stressing microbial technique and common organism identification; third-year microbiology and cellular physiology courses developing theoretical aspects; a fourth-year, hospital-based clinical microbiology rotation emphasizing isolation and identification techniques for significant pathogens; and a fourth-year, university-based, didactic course covering host defense-organism virulence interactions, infectious disease principles, and new techniques and unusual isolates as reported in the recent journal literature. Based on four years of experience with this system and in light of the publication of the 1978 American Society for Medical Technology (ASMT) Competency Statements, the Northeastern Medical Laboratory Science Program faculty is currently reexamining the continuum to insure completeness and appropriateness of overall subject content, to provide reinforcement, and to remove unnecessary duplication among the courses in the curriculum. PMID:474608

Barr, J T

1979-06-01

88

A towed body designed for side-scanning hydroacoustic surveying of fish stocks in shallow waters  

OpenAIRE

An aluminum towed body was designed for use in hydroacoustic surveying of fish stocks in shallow (2–10 m depth) inland waters. The design allows applications in deep (>10 m) water bodies as well. Test results showed that the towed body was a stable platform for the hydroacoustic transducer. The towed body features adjustable beam direction, allowing a side-looking as well as a vertical-looking mode. As the design of the towed body is simple, it can be easily constructed by any skilled craft...

Mous, P. J.; Kemper, J.; Schelvis, A.

1999-01-01

89

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

90

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

91

Honeycomb Heisenberg Spin Ladder: Unusual Ground State and Thermodynamic Properties  

OpenAIRE

The unusual ground state and thermodynamic properties of spin-1/2 two-leg honeycomb (HC) spin ladder are systematically studied by jointly utilizing various analytical and numerical methods. The HC spin ladder is found to exhibit behaviors dramatically different from those of the conventional square spin ladder. A strong relevant term nJ and a half saturation magnetization plateau that can be attributed to the formation of diluted dimer states are observed in the HC ladder, ...

Zhao, Yang; Li, Wei; Xi, Bin; Ran, Shi-ju; Zhu, Yuan-yuan; Wang, Bing-wu; Gao, Song; Su, Gang

2013-01-01

92

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 loads and should be presented in the latter as a serious potential...

Abdel-Hakim Bouzid

2014-01-01

93

Dispersal patterns of coastal fish: implications for designing networks of marine protected areas.  

Science.gov (United States)

Information about dispersal scales of fish at various life history stages is critical for successful design of networks of marine protected areas, but is lacking for most species and regions. Otolith chemistry provides an opportunity to investigate dispersal patterns at a number of life history stages. Our aim was to assess patterns of larval and post-settlement (i.e. between settlement and recruitment) dispersal at two different spatial scales in a Mediterranean coastal fish (i.e. white sea bream, Diplodus sargus sargus) using otolith chemistry. At a large spatial scale (?200 km) we investigated natal origin of fish and at a smaller scale (?30 km) we assessed "site fidelity" (i.e. post-settlement dispersal until recruitment). Larvae dispersed from three spawning areas, and a single spawning area supplied post-settlers (proxy of larval supply) to sites spread from 100 to 200 km of coastline. Post-settlement dispersal occurred within the scale examined of ?30 km, although about a third of post-settlers were recruits in the same sites where they settled. Connectivity was recorded both from a MPA to unprotected areas and vice versa. The approach adopted in the present study provides some of the first quantitative evidence of dispersal at both larval and post-settlement stages of a key species in Mediterranean rocky reefs. Similar data taken from a number of species are needed to effectively design both single marine protected areas and networks of marine protected areas. PMID:22355388

Di Franco, Antonio; Gillanders, Bronwyn M; De Benedetto, Giuseppe; Pennetta, Antonio; De Leo, Giulio A; Guidetti, Paolo

2012-01-01

94

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

95

An Evaluation of the Utah Career Ladder System.  

Science.gov (United States)

The Utah Career Ladder System was evaluated, in an effort to provide policy options for Phase II of the Career Ladder implementation in Utah and present policy recommendations. Five major data collection efforts were made: (1) analysis of district career ladder plans from 1985-86 through 1987-88; (2) a telephone survey of Utah's 40 superintendents…

Amsler, Mary; And Others

96

The ladder and the couch problem  

OpenAIRE

What is the length of the longest ladder that can be carried horizontally around the right-angled corner, created by hallways of widths a and b? To put it more mathematically, how long a line segment can be manoeuvred around the L-shaped corner? This is The Ladder Problem. The Moving Couch Problem: Given hallways of widths and meeting at a right angle, where , what is the longest rectangular couch of width , where , that can be manoeuvred around the corner? Similarly, the couch has t...

Hrast, Meta

2012-01-01

97

Non-Abelian String-Net Ladders  

CERN Document Server

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

Schulz, M D; Vidal, J

2014-01-01

98

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

OpenAIRE

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 da...

Marlene Sofia Arcifa; André Luiz Henríques Esguícero

2012-01-01

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

CFOA Based Low Pass and High Pass Ladder Filter—A New Configuration  

Directory of Open Access Journals (Sweden)

Full Text Available A new technique using signal flow graph for conversion of ladder based filter into CFOA based filter has been proposed. The proposed technique converts the existing LC ladder based filter into CFOA in low pass and high pass configuration. The design of low pass filter and high pass filter has been realized using the proposed technique. The proposed configuration is implemented using CFOA as an active device and all the capacitors are grounded. Simulation has been carried out using simulation software I-cap. The simulation results have been demonstrated and discussed.

Praween K. Sinha

2014-11-01

101

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

102

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

Science.gov (United States)

Well-designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts. PMID:25423947

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

2014-11-25

103

Design, synthesis, and characterization of ladder-type molecules and polymers. Air-stable, solution-processable n-channel and ambipolar semiconductors for thin-film transistors via experiment and theory.  

Science.gov (United States)

The design, synthesis, and characterization of new high-performance n-channel molecular/polymeric semiconductors that are solution-processable and air-stable is of great interest for the development of p-n junctions, bipolar transistors, and organic complementary circuitry (CMOS). While over the past two decades there have been many reports on n-channel materials, solution-processability and air-stability still remain as major challenges. We report here the synthesis and detailed characterization of a highly electron-deficient class of indeno[1,2-b]fluorene-6,12-dione, 2,2'-(indeno[1,2-b]fluorene-6,12-diylidene) dimalononitrile, bisindenofluorene-12,15-dione, and 2,2'-(bisindenofluorene-12,15-diylidene) dimalononitrile-based ladder-type building blocks (1-12) and their corresponding homo- and copolymers (P1-P14), and examine in detail the effects of core size, thiophene vs core regiochemistry, carbonyl vs dicyanovinylene functionality, and alkyl chain orientation on the physicochemical properties, thin film microstructures, and OFET device performance. New compounds are characterized by DSC, TGA, melting point, single-crystal X-ray diffraction (XRD), solution/thin film optical, PL, and cyclic voltammetry measurements to evaluate frontier molecular orbital energetics and intermolecular cohesive forces. Thin films are grown by vacuum deposition and spin-coating, and investigated by X-ray diffraction (XRD) and AFM. By tuning the HOMO/LUMO energetics of the present materials over a 1.1 eV range, p-type, n-type, or ambipolar charge transport characteristics can be observed, thus identifying the MO energetic windows governing majority carrier polarity and air stability. One of these systems, thiophene-terminated indenofluorenedicyanovinylene 10 exhibits an electron mobility of 0.16 cm(2)/V x s and an I(on)/I(off) ratio of 10(7)-10(8), one of the highest to date for a solution-cast air-stable n-channel semiconductor. Here we also report solution-processed ambipolar films of thiophene-based molecule 12 and copolymers P13 and P14 which exhibit electron and hole mobilities of 1 x 10(-3)-2 x 10(-4) and I(on)/I(off) ratios of approximately 10(4), representing the first examples of molecular and polymeric ambipolar semiconductors to function in air. Analysis of the operational air-stabilities of a series of thin films having different crystallinities, orientations, and morphologies suggests that operational air-stability for thermodynamically predicted (i.e., no kinetic barrier contribution) air-stable semiconductors is principally governed by LUMO energetics with minimal contribution from thin-film microstructure. The onset LUMO energy for carrier electron stabilization is estimated as -4.0 to -4.1 eV, indicating an overpotential of 0.9-1.0 eV. Density functional theory calculations provide detailed insight into molecule/polymer physicochemical and charge transport characteristics. PMID:19331320

Usta, Hakan; Risko, Chad; Wang, Zhiming; Huang, Hui; Deliomeroglu, Murat K; Zhukhovitskiy, Aleksandr; Facchetti, Antonio; Marks, Tobin J

2009-04-22

104

Teacher Orientation Manual, 1985-86. Tennessee Career Ladder Better Schools Program.  

Science.gov (United States)

This manual is designed to provide Tennessee teachers with the information needed to understand the revised Career Ladder Evaluation System and prepare them for the evaluation at Career Levels I and II. It includes the following information: (1) improvements in the revised version (1985-86); (2) fundamental beliefs and principles; (3) levels of…

Tennessee State Dept. of Education, Nashville.

105

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

106

Coupled Ladders in a Magnetic Field  

CERN Document Server

We investigate the phase transitions in two-leg ladders systems in the incommensurate phase, for which the gap is destroyed by a magnetic field ($h_{c1}< h$) and the ladder is not yet totally saturated ($h < h_{c2}$). We compute quantitatively the correlation functions as a function of the magnetic field for an isolated strong coupling ladder $J_\\perp \\gg J_\\parallel$ and use it to study the phase transition occuring in a three dimensional array of antiferromagnetically coupled ladders. The three dimensional ordering is in the universality class of Bose condensation of hard core bosons. We compute the critical temperature $T_c(h)$ as well as various physical quantities such as the NMR relaxations rate. $T_c$ has an unusual camel-like shape with a local minimum at $h=(h_{c1}+h_{c2})/2$ and behaves as $T_c \\sim (h-h_{c1})^{2/3}$ for $h\\sim h_{c1}$. We discuss the experimental consequences for compounds such as Cu$_2$(C$_5$H$_{12}$N$_2$)$_2$Cl$_4$

Giamarchi, T

1999-01-01

107

Ladders and Easels and Stools, Oh My!  

Science.gov (United States)

Describes an art lesson for high school seniors in an intermediate oil painting class. Explains that the teacher set up a still life with a ladder, easel, and a stool with a white background to capture the shadows. States that the students painted their still life in oil. (CMK)

Greenman, Geri

2002-01-01

108

29 CFR 1917.118 - Fixed ladders.  

Science.gov (United States)

...inches (0.91 m) above the top landing surface, unless grab bars or equivalent holds are provided. (7) Ladders whose pitch...rungs that are attached to walls, conical manhole sections or river cells shall: (1) Be capable of supporting a load of...

2010-07-01

109

Teacher Attitudes toward a Career Ladder.  

Science.gov (United States)

The primary reason for failure of merit pay systems is teacher dissatisfaction. A recent study examined trends in teacher attitudes toward the career ladder program of a large metropolitan school district in Arizona. Developed at the state level in response to declining student achievement indicators and failing academic standards, the Career…

Dickson, Lou Ann S.; And Others

1992-01-01

110

How Career Ladders Can Improve Instruction.  

Science.gov (United States)

Describes Salt Lake City (Utah) schools' five instructional improvement goals, including clearly developed learning objectives, effective teaching and evaluation models, appropriate assessment tools, an energized classroom environment, and career leaders to attract and retain superior teachers. Discusses career ladder systems, focusing on teacher…

Bennion, John W.

1987-01-01

111

Collective excitations in ferrimagnetic Heisenberg ladders  

Science.gov (United States)

We study ground-state properties and the low-lying excitations of Heisenberg spin ladders composed of two ferrimagnetic chains with alternating site spins (S1>S2) by using the bosonic Dyson-Maleev formalism and Lanczos numerical techniques. The emphasis is on properties of the ferrimagnetic phase, which is stable for antiferromagnetic interchain couplings J?>=0. There are two basic implications of the underlying lattice structure: (i) the spin-wave excitations form folded acoustic and optical branches in the extended Brillouin zone and (ii) the ground-state parameters (such as the on-site magnetizations and spin-stiffness constant) show a crossover behavior in the weak-coupling region 0ladder ferrimagnetic state are studied up to second order in the quasiparticle interaction and by a numerical diagonalization of ladders containing up to N=12 rungs. The presented results for the ground-state parameters and the excitation spectrum can be used in studies on the low-temperature thermodynamics of ferrimagnetic ladders.

Ivanov, N. B.; Richter, J.

2001-04-01

112

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

113

The use of morphometric analysis to predict the swimming efficiency of two Neotropical long-distance migratory species in fish passage  

OpenAIRE

This study investigated the external body morphology (based on morphometric data) and the swimming efficiency in fish passages (based on the ascent time in a fish ladder) of two Neotropical long-distance migratory species. The fish were collected in the fish ladder of the Porto Primavera Hydroelectric Power Plant (known as Engenheiro Sergio Motta), upper Paraná River, Brazil. The species differ in several morphometric ratios related to swimming performance. Prochilodus lineatus exhibited a h...

Lucileine de Assumpção; Maristela Cavicchioli Makrakis; Sergio Makrakis; Ricardo Luiz Wagner; Patrícia Sarai da Silva; Ariane Furtado de Lima; Elaine Antoniassi Luiz Kashiwaqui

2012-01-01

114

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

Scientific Electronic Library Online (English)

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

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

2006-06-01

115

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

116

The spin-1 ladder A bosonization study  

CERN Document Server

We construct a field-theoretic description of two coupled spin-1 Heisenberg chains, starting with the known representation of a single spin-1 chain in terms of Majorana fermions (or Ising models). After reexamining the bosonization rules for two Ising models, taking particular care of order and disorder operators, we obtain a bosonic description of the spin-1 ladder. From renormalization-group and mean-field arguments, we conclude that, for a small interchain coupling, the spin-1 ladder is approximately described by three decoupled, two-frequency sine-Gordon models. We then predict that, starting with decoupled chains, the spin gap decreases linearly with interchain coupling, both in the ferromagnetic and antiferromagnetic directions. Finally, we discuss the possibility of an incommensurate phase in the spin-1 zigzag chain.

Allen, D

2000-01-01

117

Stark-ladder effect on chemisorption  

Science.gov (United States)

Chemisorption on an electrified finite chain of atoms ( electrochemisorption) is investigated by the recursive Green-function (GF) technique, whereby the surface and adatom GFs can be expressed as ratios of Bessel functions. The Anderson-Newns model provides a self-consistent treatment of the electrochemisorption energy and adatom charge transfer. The Stark-ladder effect on magnetic and non-magnetic electrochemisorption is discussed for H?Ti and H?Cr systems.

English, R. A.; Davison, S. G.

1998-02-01

118

Guest Editorial: Building Ladders to the Stars  

Science.gov (United States)

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

George D. "Pinky" Nelson

2008-09-01

119

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

120

Raman Scattering from Magnetic Excitations in coupled Spin Ladders  

CERN Document Server

We consider Raman scattering of coupled two leg spin ladders in the Fleury-Loudon regime. We derive the dependence of the intensity with polarization of the incoming light and temperature and discuss the effect of interaction of the elementary excitations on the shape of the spectrum. We show that Raman scattering spectrum is sensitive to the effective dimensionality of the coupled ladder system, making Raman scattering useful to discriminate true ladder systems from quasi two dimensional spin gap systems.

Citro, R

2000-01-01

121

A Critical Review of the “Ladder of Investment” Approach  

OpenAIRE

The “ladder of investment” is a regulatory approach proposed by Cave (2006), which has been widely embraced by national regulatory authorities in the European telecommunications sector. The approach entails providing entrants, successively, with different levels of access—the “rungs” of the investment ladder, while inducing them to climb the ladder by setting an access charge that increases over time or by withdrawing access obligations after some pre-determined date (i.e., by setti...

Dogan, Pinar; Bourreau, Marc; Manant, Matthieu

2010-01-01

122

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

International Nuclear Information System (INIS)

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

123

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

Science.gov (United States)

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

Garletts, Joseph A

2002-01-01

124

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

125

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

Science.gov (United States)

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

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

2014-12-01

126

D0 Silicon Upgrade: Ladder Removal Stress Analysis  

International Nuclear Information System (INIS)

Two different methods will be used to affix ladders to the active bulkhead. Layer 1 and layer 3 ladders will be attached to the active bulkhead using pins. To provide a highly conductive thermal path between these ladders and the cooling channel in the active bulkhead, a small amount of thermally conductive grease will be applied to the bulkhead just prior to ladder installation. Layer 2 and layer 4 ladders will be attached using the same method with the exception that thermally conductive epoxy will be used in lieu of grease. The epoxy is necessary in the outer two layers to maintain barrel rigidity. One major point of concern is the removal of the epoxied ladders. If removal of one of these ladders becomes necessary, it is unclear if the epoxy bond can be broken without damaging the silicon. This report is an attempt to estimate the amount of force necessary to remove a ladder, and the resulting stress that force produces in the silicon. The force necessary to remove an epoxied ladder from a bulkhead is calculated. The resulting silicon stress is also calculated.

127

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

Science.gov (United States)

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

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

2015-06-01

128

Investigation of paramagnetic characteristics of ladder and partly-ladder polychinons  

International Nuclear Information System (INIS)

It was shown that for ?-irradiation doses of approximately 0.5x105 mrad and reactor irradiation up to approximately 5x1019 n/cm2 the ladder polymers heated up to 500 deg C, practically did not change their characteristics. (author)

129

Surface plasmon polariton Wannier-Stark ladder.  

Science.gov (United States)

The propagation of a surface plasmon polariton on a planar metal surface perturbed by N equally spaced rectangular grooves, each with the same width but with varying depths, is investigated by the finite-difference time-domain method. For a linear dependence of the depth of the nth groove on n, the transmissivity of the surface plasmon polariton and of the power radiated into the vacuum above the surface, as functions of its frequency, consist of N equally spaced dips and peaks, respectively. These are the signatures of the surface plasmon polariton analog of a Wannier-Stark ladder. PMID:24690851

Kuzmiak, V; Maradudin, A A; Méndez, E R

2014-03-15

130

Getting to the Bottom of a Ladder Problem  

Science.gov (United States)

In this paper, the author introduces a simple problem relating to a pair of ladders. A mathematical model of the problem produces an equation which can be solved in a number of ways using mathematics appropriate to "A" level students or first year undergraduates. The author concludes that the ladder problem can be used in class to develop and…

McCartney, Mark

2002-01-01

131

Counselor Orientation Manual. Tennessee Career Ladder Better Schools Program.  

Science.gov (United States)

This document is an orientation manual for the Career Ladder Counselor Evaluation System, a part of the Tennessee Career Ladder Better Schools Program. The evaluation system for guidance counselors was developed by using the best ideas from educational research and from counselors in Tennessee. The system was field tested in the fall of 1985.…

Tennessee State Dept. of Education, Nashville.

132

Percent Stomach Emptiness in Fish Collections: Sources of Variation and Study Design Implications  

Science.gov (United States)

We summarized fish stomach content data from 369,000 fish from 402 species in 1,096 collections made between 1925 and 2009 and report on the percentage of individuals with empty stomachs (PES). The mean PES among all species, locations, habitats, dates, and collection methods was...

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

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)

135

Teacher Career Ladders in Britain. A Study of Their Structure and Impact.  

Science.gov (United States)

A career ladder for teachers has been used in Great Britain for over 40 years. The ladder contains five steps with teachers progressing up the ladder by competitive promotion. This study investigated the historical development, structure, and consequences on teacher behavior of the career ladder system used in the United Kingdom. The study was…

Murphy, Michael J.; And Others

136

Clinical career ladders: application to hospital pharmacy practice.  

Science.gov (United States)

The reasons for job dissatisfaction among hospital pharmacists are reviewed, and an option for ameliorating the problem by offering clinical career ladders is advanced. Not enough new pharmacists are being trained to replace those leaving the profession, and hospital pharmacy managers seeking to recruit and retain quality pharmacists are facing stiff competition from retail outlets, academia, and the pharmaceutical industry. Hospital staff pharmacists report less of a sense of accomplishment than other workers and are more likely to change jobs. Although inadequate pay and benefits are frequently cited, one investigator found that the greatest source of dissatisfaction was the lack of opportunity for advancement. Other professions facing similar problems have experimented with a system of parallel career ladders in which alternatives to the traditional managerial advancement track are offered. Staff nurses on a clinical ladder remain in a direct patient-care role while ascending a hierarchy of clinical practice levels; each level brings greater responsibility and rewards. Outcomes have included improved recruitment, decreased turnover, and increased interest in educational programs. In pharmacy, each level of a clinical career ladder would be defined by explicit criteria for knowledge and skill in patient care and drug therapy. As in nursing, such a ladder would create advancement opportunities and reward the acquisition of knowledge and skills. Several hospital pharmacy departments now offer clinical career ladders. Implementation of clinical career ladders has the potential to enhance the job satisfaction of hospital pharmacists and improve their recruitment and retention. PMID:2589338

Smith, J E; Shane, R

1989-11-01

137

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

138

Ladder Climbing and Autoresonant Acceleration of Plasma Waves  

CERN Document Server

Classical plasma waves are predicted to exhibit quantumlike ladder climbing, which is achieved by chirped modulations of the background density. An equivalence with the quantum particle in a box is identified and used to calculate the efficiency and the rate of this effect. In the limit of densely spaced spectrum, ladder climbing transforms into continuous autoresonance; plasmons may then be manipulated by chirped background modulations much like electrons are autoresonantly manipulated by chirped fields. Such ladder climbing and autoresonance effects are also predicted for other classical waves by means of a unifying Lagrangian theory.

Barth, Ido; Fisch, Nathaniel J

2015-01-01

139

Vortices in an annular Josephson ladder  

Science.gov (United States)

We present numerically the static vortex configurations in an annular Josephson ladder subject to a transverse magnetic field. When the applied magnetic field is small, the supercurrents flow only along the angular direction. In that case, the phases of the inner and outer rings are coupled each other with the same winding numbers of vorticity. Such a phase-locking remains until the magnetic field reaches a certain high value over which Josephson vortices begin to appear between the two rings. The flux imbalance of the inner and outer rings leads to the different winding numbers of vorticity and the appearance of vortices in some plaquettes. The vortex configurations for a given magnetic field are found not to be unique but to exhibit other excited states of vortices with the higher energies and lower probabilities of occurrence.

Lee, K. H.

2015-03-01

140

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

OpenAIRE

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

Nieuwenhuis, Taco; Tjon, J. A.

1996-01-01

141

Stomach emptiness in fishes: Sources of variation and study design implications  

Science.gov (United States)

This study summarizes fish stomach content data from 369,000 fish from 402 species in 1,096 collections and reports on the percentage of individuals with empty stomachs. The mean percentage of individuals with empty stomachs among all species, locations, habitats, seasons, regions, and collection methods was 26.4%. Mean percentage of individuals with empty stomachs varied significantly among fish collection gear types, taxonomic orders, trophic groups, feeding behaviors, and habitats, and with species length at maturity. Most of the variation in percentage of individuals with empty stomachs was explained by species length at maturity, fish collection gear type, and two autecological factors: trophic group (piscivore percentage of individuals with empty stomachs > non-piscivore percentage of individuals with empty stomachs) and feeding habitat (water column feeder percentage of individuals with empty stomachs > benthic feeder percentage of individuals with empty stomachs). After accounting for variation with fish length, the percentage of individuals with empty stomachs did not vary with the stomach removal collection method (dissection vs. gastric lavage), feeding time (diurnal or nocturnal), or time of collection (day or night). The percentage of individuals with empty stomachs was similar between fresh and saltwater fish, but differed within finer habitat classifications and appeared to follow a general prey availability or productivity gradient: percentage of individuals with empty stomachs of open ocean collections > estuary collections, lentic > lotic, and pelagic > littoral. Gear type (active or passive) was the most influential factor affecting the occurrence of empty stomachs that can be readily controlled by researchers.

Vinson, M.R.; Angradi, T.R.

2011-01-01

142

29 CFR 1910.26 - Portable metal ladders.  

Science.gov (United States)

...nonslip material for the safety of the user...maximum serviceability, safety, and to eliminate...and regulations are essential to the life of the equipment and the safety of the user. ...ladders are exposed to oil and grease,...

2010-07-01

143

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

Science.gov (United States)

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

Powell, Martin

2014-01-01

144

Magnetization Curves of Antiferromagnetic Heisenberg Spin-1/2 Ladders  

CERN Document Server

Magnetization processes of spin-1/2 Heisenberg ladders are studied using strong-coupling expansions, numerical diagonalization of finite systems and a bosonization approach. We find that the magnetization exhibits plateaux as a function of the applied field at certain rational fractions of the saturation value. Our main focus are ladders with 3 legs where plateaux with magnetization one third of the saturation value are shown to exist.

Cabra, D C; Pujol, P

1997-01-01

145

Magnetization Curves of Antiferromagnetic Heisenberg Spin- 12 Ladders  

Science.gov (United States)

Magnetization processes of spin- 1 2 Heisenberg ladders are studied using strong-coupling expansions, numerical diagonalization of finite systems, and a bosonization approach. We find that the magnetization exhibits plateaux as a function of the applied field at certain rational fractions of the saturation value. Our main focus is on ladders with three legs where plateaux with magnetization one third of the saturation value are shown to exist.

Cabra, D. C.; Honecker, A.; Pujol, P.

1997-12-01

146

Development and benefits of a pharmacy technician career ladder.  

Science.gov (United States)

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

Strozyk, W R; Underwood, D A

1994-03-01

147

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

148

New Results for Heisenberg Spin Ladders Using a Plaquette Basis  

Science.gov (United States)

Heisenberg spin ladders consist of interacting parallel quantum spin chains; interactions are between nearest-neighbors only. These systems are of current interest because of their rich and subtle dynamics as well as their possible relevance to high-temperature superconductors.(see, e.g.), Physics Today, October, 1996, p.17 We have formulated a novel ``plaquette basis'' for computing properties of 2-leg spin ladders. The Hamiltonian is diagonal for individual plaquettes in this basis which proves to be useful both calculationally and for providing a physical picture of the dynamics of the ladders. Implementation of this basis requires Racah algebra techniques familiar in nuclear and atomic physics but relatively unknown in condensed matter physics. We present plaquette-basis calculations for various properties of 2-leg ladders with up to 8 rungs. For the larger ladders, we use COntractor REnormalization (CORE(C.J. Morningstar and M. Weinstein, hep-lat)/9603016) methods to correct for truncations. We also present a Renormalization Group scheme which permits us to treat arbitrarily large ladders. Comparisons to and extensions of previous calculations will be presented.

Shepard, J. R.; Piekarewicz, J.

1997-10-01

149

Meet the surrogate fish  

International Nuclear Information System (INIS)

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

150

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

151

Economic integration in the quality ladder model  

Scientific Electronic Library Online (English)

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

Eduardo Correia de, Souza.

2008-12-01

152

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

Scientific Electronic Library Online (English)

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

Marlene Sofia, Arcifa; André Luiz Henríques, Esguícero.

2012-10-01

153

Spin and thermal conductivity of quantum spin chains and ladders  

Science.gov (United States)

We study the spin and thermal conductivity of spin-1/2 ladders and chains at finite temperature, relevant for experiments with quantum magnets. Using a state-of-the-art density matrix renormalization group algorithm, we compute the current autocorrelation functions on the real-time axis and then carry out a Fourier integral to extract the frequency dependence of the corresponding conductivities. The finite-time error is analyzed carefully. We first investigate the limiting case of spin-1/2 X X Z chains, for which our analysis suggests nonzero dc conductivities in all interacting cases irrespective of the presence or absence of spin Drude weights. For ladders, we observe that all models studied are normal conductors with no ballistic contribution. Nonetheless, only the high-temperature spin conductivity of X X ladders has a simple diffusive, Drude-like form, while Heisenberg ladders exhibit a more complicated low-frequency behavior. We compute the dc spin conductivity down to temperatures of the order of T ˜0.5 J , where J is the exchange coupling along the legs of the ladder. We further extract mean-free paths and discuss our results in relation to thermal conductivity measurements on quantum magnets.

Karrasch, C.; Kennes, D. M.; Heidrich-Meisner, F.

2015-03-01

154

Measurements of Prototype Ladders for the TT station with a Laser  

CERN Document Server

Results of measurements made in a laser test-stand on TT prototype ladders read out via long Kapton flex cables are described. The ladders give acceptable performance in terms of signal shape, signal remainder and rise-time.

Gassner, J; Steinkamp, O; Vollhardt, A; Volyanskyy, D

2005-01-01

155

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

Directory of Open Access Journals (Sweden)

Full Text Available A factorial design approach was applied to optimize the PCR yield of 2 kb fragment involved in preparing DNA ladder. On applying response surface methodology, the effect of six independent variables was studied. From this study we concluded that three fold increase was obatainable upon optimization under the following conditions: primer concentration, 10 pmole; number of cycles, 24; Taq concentration, 2.75 U; Mg+2 concentration, 1.97 mM; annealing temperature, 57°C and extension time, 72 sec. A verification of the predicted model revealed a 91.5% accuracy level.

Yasser R. Abdel-Fattah

2006-01-01

156

Growth of deformation bands into echelon and ladder geometries  

Science.gov (United States)

We investigate the growth of cataclastic deformation bands in porous sandstone into Riedel, ladder, and ``radiator rock'' arrays. New field observations and mechanical modeling of DB growth using the distortional strain energy density criterion demonstrate that the physical control of these geometries is a contractional (mode-II) stepover between two echelon bands. Propagation of bands under pre-peak conditions, before Coulomb frictional sliding (faulting) begins, is not impeded by the echelon stepover geometry (as it is for brittle fractures under peak stress); continued in-plane growth of echelon bands creates ladders from stepovers. Successive addition of stepovers/ladders along their shearing direction produces Riedel geometries, whereas addition normal to strike produces radiator rock (the damage zone) as a consequence of strain hardening of bands and linked stepovers. The new framework has implications for fluid flow in groundwater aquifers, hydrothermal and precious metals systems, and petroleum fields.

Schultz, Richard A.; Balasko, Clara M.

2003-10-01

157

Critical properties of S=12 Heisenberg ladders in magnetic fields  

Science.gov (United States)

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 of as a model Hamiltonian of the organic spin ladder compound Cu2(1,4-diazacycloheptane)2Cl4. Numerical results are compared with experimental results of temperature dependence of the NMR relaxation rate 1/T1.

Usami, Mamoru; Suga, Sei-Ichiro

1998-12-01

158

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 ...

159

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.

160

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

161

Efficient infrared upconversion via a ladder-type atomic configuration  

CERN Document Server

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

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

2012-01-01

162

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. 3 figs.

Renschler, C.L.; White, C.A.; Carter, R.M.

1998-09-29

163

Notebook Positioning by Perceptual Map and Laddering Method  

Directory of Open Access Journals (Sweden)

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

Mehdi Zaribaf

2012-01-01

164

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

165

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

Directory of Open Access Journals (Sweden)

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

T.Chalama Reddy

2013-06-01

166

Career Ladders and Teacher Incentives: The Utah Experiment. Part I: The Implementation. Final Report: Secretary's Discretionary Program Implementation Grant to Develop Teacher Incentive Structures.  

Science.gov (United States)

This volume, the first of two reports on development of teacher incentive structures, focuses on implementation of a career ladder design and teacher evaluation experiment in four Utah school districts. The report has five sections. Section 1 describes study background and implementation of an evaluation-reward system that featured data collection…

Peterson, Ken; Kauchak, Don

167

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

168

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-09-11

169

Schroedinger operators with the q-ladder symmetry algebras  

Science.gov (United States)

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

Skorik, Sergei; Spiridonov, Vyacheslav

1994-01-01

170

Compass model on a ladder and square clusters  

International Nuclear Information System (INIS)

We obtained exact specific heat of the quantum compass model on the square L x L clusters with L = 2, 3, 4, 5 using Kernel Polynomial Method and compare them with the specific heat of a large compass ladder. Intersite correlations found in the ground state for these systems demonstrate that the quantum compass model differs from its classical version.

171

Topological order in Josephson junction ladders with Mobius boundary conditions  

CERN Document Server

We propose a CFT description for a closed one-dimensional fully frustrated ladder of quantum Josephson junctions with Mobius boundary conditions, in particular we show how such a system can develop topological order. Such a property is crucial for its implementation as a "protected" solid state qubit.

Cristofano, G; Naddeo, A

2005-01-01

172

Digging Deeper: The Laddering Interview, a Tool for Surfacing Values  

Science.gov (United States)

Personally held values play a fundamental role in business. As such, it is critical that students understand the nature of values pertaining to the workplace. Using an innovative classroom exercise, laddering, business students interview individuals to identify values that influence choices. Objectives are to help students understand the role of…

Trocchia, Philip J.; Swanson, Diane L.; Orlitzky, Marc

2007-01-01

173

Topological order in Josephson junction ladders with Mobius boundary conditions  

Science.gov (United States)

We propose a CFT description for a closed one-dimensional fully frustrated ladder of quantum Josephson junctions with Mobius boundary conditions; in particular we show how such a system can develop topological order. Such a property is crucial for its implementation as a 'protected' solid state qubit.

Cristofano, Gerardo; Marotta, Vincenzo; Naddeo, Adele

2005-03-01

174

Single-particle potential from resummed ladder diagrams  

CERN Document Server

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

Kaiser, Norbert

2013-01-01

175

Ladder Operators for Some Spherically Symmetric Potentials in Quantum Mechanics  

Science.gov (United States)

The energy levels of the free field, Coulomb potential, and the three-dimensional harmonic oscillator are found using the Dirac operator formalism by the construction of suitable ladder operators. The degeneracy of each level is also discussed. (Author/GA)

Newmarch, J. D.; Golding, R. M.

1978-01-01

176

Career Ladder Policy for Teachers: The Case of Ghana  

Science.gov (United States)

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

Osei, George M.

2008-01-01

177

Sequencing DNA using mass spectrometry for ladder detection.  

OpenAIRE

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

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

1998-01-01

178

Costs of School Teacher Evaluation in a Career Ladder System.  

Science.gov (United States)

This study estimated the cost effectiveness of a teacher career ladder reform program. An innovative multiple data source teacher evaluation system was used. Teacher time and dollar costs ranged considerably for different data sources and individual teachers; the annual dollar cost of providing eight data sources was $44.70 per teacher. (JD)

Peterson, Kenneth D.

1989-01-01

179

Plaquette basis for the study of Heisenberg ladders  

Science.gov (United States)

We employ a plaquette basis-generated by coupling the four spins in a 2×2 lattice to a well-defined total angular momentum-for the study of Heisenberg ladders with antiferromagnetic coupling. Matrix elements of the Hamiltonian in this basis are evaluated using standard techniques in angular-momentum (Racah) algebra. We show by exact diagonalization of small (2×4 and 2×6) systems that in excess of 90% of the ground-state probability is contained in a very small number of basis states. These few basis states can be used to define a severely truncated basis which we use to approximate low-lying exact eigenstates. We show how, in this low-energy basis, the isotropic spin-1/2 Heisenberg ladder can be mapped onto an anisotropic spin-1 ladder for which the coupling along the rungs is much stronger than the coupling between the rungs. The mapping thereby generates two distinct energy scales which greatly facilitates understanding the dynamics of the original spin-1/2 ladder. Moreover, we use these insights to define an effective low-energy Hamiltonian in accordance to the contractor renormalization group (CORE) method. We show how a simple range-2 CORE approximation to the effective Hamiltonian to be used with our truncated basis reproduces the low-energy spectrum of the exact 2×6 theory at the <~1% level.

Piekarewicz, J.; Shepard, J. R.

1997-09-01

180

A Plaquette Basis for the Study of Heisenberg Ladders  

CERN Document Server

We employ a plaquette basis-generated by coupling the four spins in a $2\\times2$ lattice to a well-defined total angular momentum-for the study of Heisenberg ladders with antiferromagnetic coupling. Matrix elements of the Hamiltonian in this basis are evaluated using standard techniques in angular-momentum (Racah) algebra. We show by exact diagonalization of small ($2\\times4$ and $2\\times6$) systems that in excess of 90% of the ground-state probability is contained in a very small number of basis states. These few basis states can be used to define a severely truncated basis which we use to approximate low-lying exact eigenstates. We show how, in this low-energy basis, the isotropic spin-1/2 Heisenberg ladder can be mapped onto an anisotropic spin-1 ladder for which the coupling along the rungs is much stronger than the coupling between the rungs. The mapping thereby generates two distinct energy scales which greatly facilitates understanding the dynamics of the original spin-1/2 ladder. Moreover, we use thes...

Piekarewicz, J

1997-01-01

181

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

182

Dissipation, voltage profile and Levy dragon in a special ladder network  

International Nuclear Information System (INIS)

A ladder network constructed by an elementary two-terminal network consisting of a parallel resistor-inductor block in series with a parallel resistor-capacitor block sometimes is said to have a non-dispersive dissipative response. This special ladder network is created iteratively by replacing the elementary two-terminal network in place of the resistors. In this paper, it will be demonstrated that, in fact, non-dispersive dissipative response conclusion of this special ladder network is not accurate for steady-state condition. Furthermore, the voltage profile of this special ladder network exhibits a fractal form called the Levy C curve or Levy dragon in a certain condition. Therefore, this special ladder network may be called the Levy ladder network. This ladder network might be interesting for physics and electrical engineering students and they may encounter when dealing with this network series and parallel combinations of impedances.

183

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

184

Tensor network states and ground-state fidelity for quantum spin ladders  

Science.gov (United States)

We have developed an efficient tensor network algorithm for spin ladders, which generates ground-state wave functions for infinite-size quantum spin ladders. The algorithm is able to efficiently compute the ground-state fidelity per lattice site, a universal phase transition marker, thus offering a powerful tool to unveil quantum many-body physics underlying spin ladders. To illustrate our scheme, we consider the two-leg and three-leg Heisenberg spin ladders with staggering dimerization, the two-leg Heisenberg spin ladder with cyclic four-spin exchange, and the ferromagnetic frustrated two-leg ladder. The ground-state phase diagrams thus yielded are reliable, compared with the previous studies based on the the exact diagonalization and the density matrix renormalization group. Our results indicate that the ground-state fidelity per lattice site successfully captures quantum criticalities in spin ladders.

Li, Sheng-Hao; Shi, Qian-Qian; Su, Yao-Heng; Liu, Jin-Hua; Dai, Yan-Wei; Zhou, Huan-Qiang

2012-08-01

185

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

186

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

Science.gov (United States)

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

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

2015-05-01

187

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

DEFF Research Database (Denmark)

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

Stephansen, Karen; Mattebjerg, Maria

2015-01-01

188

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

189

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

Science.gov (United States)

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

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

2014-01-01

190

Ladder-type oligo-p-phenylene-containing copolymers with high open-circuit voltages and ambient photovoltaic activity.  

Science.gov (United States)

Four ladder-type oligo-p-phenylene containing donor-acceptor copolymers were designed, synthesized, and characterized. The ladder-type oligo-p-phenylene was used as an electron donor unit in these copolymers to provide a deeper highest occupied molecular orbital (HOMO) level for obtaining polymer solar cells with a higher open-circuit voltage, while 4,7-dithien-2-yl-2,1,3-benzothiadiazole or 5,8-dithien-2-yl-2,3-diphenylquinoxaline was chosen as an electron acceptor unit to tune the electronic band gaps of the polymers for a better light harvesting ability. These copolymers exhibit field-effect mobilities as high as 0.011 cm(2)/(V s). Compared to fluorene containing copolymers with the same acceptor unit, these ladder-type oligo-p-phenylene containing copolymers have enhanced and bathochromically shifted absorption bands and much better solubility in organic solvents. Photovoltaic applications of these polymers as light-harvesting and hole-conducting materials are investigated in conjunction with [6,6]-phenyl-C61-butyric acid methyl ester (PC(61)BM) or [6,6]-phenyl-C71-butyric acid methyl ester (PC(71)BM). Without extensive optimization work, a power conversion efficiency (PCE) of 3.7% and a high open-circuit voltage of 1.06 V are obtained under simulated solar light AM 1.5 G (100 mW/cm(2)) from a solar cell with an active layer containing 20 wt % ladder-type tetra-p-phenylene containing copolymer (P3FTBT6) and 80 wt % PC(61)BM. Moreover, a high PCE of 4.5% was also achieved from a solar cell with an active layer containing 20 wt % P3FTBT6 and 80 wt % PC(71)BM. PMID:20102195

Zheng, Qingdong; Jung, Byung Jun; Sun, Jia; Katz, Howard E

2010-04-21

191

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

Science.gov (United States)

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

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

2007-01-01

192

Phase diagram of a bosonic ladder with two coupled chains  

International Nuclear Information System (INIS)

We study a bosonic ladder with two coupled chains using the finite-size density-matrix renormalization group method. We show that in a commensurate bosonic ladder the critical on-site interaction (UC) for the superfluid to Mott insulator transition gets larger as the interchain hopping (tperpendicular) increases. We analyze this quantum phase transition and obtain the phase diagram in the tperpendicular-U plane. We also consider the asymmetric case where the on-site interactions are different in the two chains and have shown that the system as a whole will not be in the Mott insulator phase unless both the chains have on-site interactions greater than the critical value

193

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.

194

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

Science.gov (United States)

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

Guo, WeiJie; Fan, DaiHe; Wei, LianFu

2015-02-01

195

Two-point resistance of the Möbius ladder  

Science.gov (United States)

Exact formulas for the two-point resistance and the Kirchhoff index of the Möbius ladder are given based on the recently developed analytical approach by Chair (2012 Ann. Phys. 327 2899). The expression for the two-point resistance is written in terms of the two-point resistance of N/2-cycle graph and the Bejaia and the Pisa numbers recently introduced by the first author.

Chair, Noureddine; Dannoun, Elham Mohammed Ali

2015-03-01

196

Solution of a two-leg spin ladder system  

International Nuclear Information System (INIS)

A model for a spin-1/2 ladder system with two legs is introduced. It is demonstrated that this model is solvable via the Bethe ansatz method for arbitrary values of the rung coupling J. This is achieved by a suitable mapping from the Hubbard model with appropriate twisted boundary conditions. We determine that a phase transition between gapped and gapless spin excitations occurs at the critical value Jc=1/2 of the rung coupling

197

Topological Phase Transition in the Extended Cluster Compass Ladder  

OpenAIRE

We have studied the exact solution of the extended cluster compass ladder, which is equivalent to extended quantum compass model with cluster interaction between next-nearest-neighbor spins, by using the Jordan-Wigner transformation. We show that this model is always gapfull except at the critical surfaces where the energy gap disappears. We obtain the analytic expressions of all critical couplings which drive quantum phase transitions. This model shows a rich phase diagram ...

Jafari, R.; Mahdavifar, S.

2013-01-01

198

Generalized Ladder Operators for Shape-invariant Potentials  

CERN Document Server

A general form for ladder operators is used to construct a method to solve bound-state Schr\\"odinger equations. The characteristics of supersymmetry and shape invariance of the system are the start point of the approach. To show the elegance and the utility of the method we use it to obtain energy spectra and eigenfunctions for the one-dimensional harmonic oscillator and Morse potentials and for the radial harmonic oscillator and Coulomb potentials.

Filho, E D; Filho, Elso Drigo

2001-01-01

199

Charge kinks as Raman scatterers in quarter-filled ladders  

International Nuclear Information System (INIS)

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

200

Charge kinks as Raman scatterers in quarter-filled ladders  

Energy Technology Data Exchange (ETDEWEB)

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

Sherman, E. Ya.; Ambrosch-Draxl, C.; Lemmens, P.; Guntherodt, G.; van Loosdrecht, P. H. M.

2001-06-01

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

Charge kinks as Raman scatterers in quarter-filled ladders  

Science.gov (United States)

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

Sherman, E. Ya.; Ambrosch-Draxl, C.; Lemmens, P.; Güntherodt, G.; van Loosdrecht, P. H.

2001-06-01

203

Laplace-Runge-Lenz vector, ladder operators and supersymmetry  

Energy Technology Data Exchange (ETDEWEB)

We show that the Laplace-Runge-Lenz vector (LRLV) generates the Infeld-Hull radial factorization and the pair of isospectral Hamiltonians for the non-relativistic Kepler-Coulomb quantum problem. To do this we only use the LRLV and arguments of general soundness. Finally, the well known restrictions on the orbital angular momentum and the principal quantum numbers are rederived from the corresponding ladder operators. (author)

Mota, R.D. [Unidad Profesional Interdisciplinaria de Ingenieria y Tecnologias Avanzadas, Mexico DF (Mexico)]. E-mail: mota@gina.esfm.ipn.mx; Garcia, J.; Granados, V.D. [Departamento de Fisica, Escuela Superior de Fisica y Matematicas, Mexico DF (Mexico)

2001-03-16

204

Single-particle potential from resummed ladder diagrams  

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-11-15

205

Phase Diagram of the Heisenberg Spin Ladder with Ring Exchange  

OpenAIRE

We investigate the phase diagram of a generalized spin-1/2 quantum antiferromagnet on a ladder with rung, leg, diagonal, and ring-exchange interactions. We consider the exactly soluble models associated with the problem, obtain the exact ground states which exist for certain parameter regimes, and apply a variety of perturbative techniques in the regime of strong ring-exchange coupling. By combining these approaches with considerations related to the discrete Z_4 symmetry of...

Gritsev, Vladimir; Normand, Bruce; Baeriswyl, Dionys

2003-01-01

206

Study of the hidden orders in quantum spin ladders  

Science.gov (United States)

Dimerized antiferromagnetic two- and three-leg spin-l/2 ladders are known to exhibit a quantum critical phase transition between gapped phases in the ground state. The existence or absence of criticality is dependent on the dimerization pattern, i.e. the repetition of the strong and weak couplings on the legs. A parallel (a.k.a columnar) arrangement is never critical, whereas an alternated (a.k.a staggered) configuration possesses a gapless quantum critical point. Interestingly, these unconventional gapped phases cannot be distinguished in the context of conventional Landau theory by symmetry breaking or a long-range local order parameter. In such exotic systems, however, it is possible to define a non-local hidden order parameter called the string order parameter, which is non-zero in one phase and vanishes in the other. In this thesis an exact diagonalization technique based on the Lanczos Algorithm is used to calculate exact ground state energies, energy gaps and string order parameters of dimerized two- and three-leg Heisenberg ladders. Results obtained using this method for ladders with sizes up to 30 spins will be given. Finite size effects are taken into account using a critical scaling analysis which yields estimates of the critical exponents. Based on this numerical study, a qualitative analysis of the hidden orders and/or symmetries of the direct Hamiltonian will be given, with special emphasis on the string order parameter in each of the dimerization patterns. It will be shown that the string order parameter indicates the quantum critical point in the staggered configuration of both the two-leg and three-leg dimerized antiferromagnetic ladders.

Gibson, Sandra J.

207

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

208

Climbing the ladder from novice to expert plastic surgeon.  

Science.gov (United States)

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

Weber, Robert A; Aretz, H Thomas

2012-07-01

209

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

210

Control of Population Flow in Coherently Driven Quantum Ladders  

International Nuclear Information System (INIS)

A technique for adiabatic control of the population flow through a preselected decaying excited level in a three-level quantum ladder is presented. The population flow through the intermediate or upper level is controlled efficiently and robustly by varying the pulse delay between a pair of partly overlapping coherent laser pulses. The technique is analyzed theoretically and demonstrated in an experiment with Na2 molecules

211

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)

212

“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

213

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

214

"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

215

Clinical career ladders: the Moses H. Cone Memorial Hospital.  

Science.gov (United States)

A competence- and achievement-based advancement program developed for pharmacists at The Moses H. Cone Memorial Hospital, a 530-bed community teaching hospital, is described. In 1985 pharmacy management recognized the need to provide an incentive program to reward achievements by staff clinical pharmacists, recognize their increased responsibilities, and increase the department's ability to retain qualified practitioners. Adding another rung to the existing administrative career ladder was not desirable, so a new job category, pharmacist II, was created. Employees are evaluated for promotion to pharmacist II on the basis of tenure, performance, and elective professional and service activities. A point system is used to objectively score achievements; to be promoted, an employee must accumulate 50 points during a two-year period. The number of staff pharmacists who can advance is limited not arbitrarily but rather by the application of challenging criteria. Employees are responsible for submitting documentation of their achievements to a review committee, which meets quarterly to evaluate applications and award points. Of 13 applicants since 1985, 10 have been promoted. Because of problems in evaluating the performance of pharmacist II employees, providing them time to conduct research, and incorporating specialty practice areas into the program, plans are being made to institute a more structured career ladder system with separate managerial, clinical, and educational tracks. A competence- and achievement-based advancement program with a single step was an improvement over the former system but lacked the balance and comprehensiveness offered by more structured career ladder programs. PMID:2589341

Crouch, J B; Douglas, J B; Wheeler, D S

1989-11-01

216

Clinical career ladders: St. Vincent Hospital and Health Care Center.  

Science.gov (United States)

The career ladder program developed for pharmacists at St. Vincent Hospital and Health Care Center (SVH), a 625-bed community hospital, is described. Before 1986 the only advancement program for pharmacists at SVH was a traditional managerial one. The need for a system that would reward outstanding pharmacists both professionally and financially and prevent increases in turnover led to the development of a three-tiered ladder system in which clinical expertise and participation in elective professional activities are important keys to advancement. All baccalaureate-level pharmacists are hired at level I. Level II represents the standard of pharmacy practice at SVH. Pharmacists promoted to level III have made a major contribution. Advancement is contingent upon the accumulation of points awarded for performance evaluations, elective activities, and tenure. In addition to distributive and clinical duties, level II and III pharmacists must participate in special projects or on committees. Promoted pharmacists must accumulate additional points annually to remain at the higher level. The program was objected to by some staff members who believed that it would cut into personal time and give certain pharmacists preferred work schedules. Nevertheless, several promotions have quickened interest in the program, and participation in advancement-related activities has increased. The career ladder program has stimulated employees' professional and financial growth, enhanced the quality and quantity of pharmaceutical services, and averted potential increases in staff turnover. PMID:2589343

Wills, T M; Garing, T L

1989-11-01

217

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.

218

Functional Renormalization Group calculation of the Fermi surface of a spin-ladder  

CERN Document Server

We study non conventional superconductivity on a ladder, improving the predictions of the Hubbard model. The determination of the Fermi surface, in 2 or 3 dimensions, remains a very hard task, but it is exactly solvable for a single ladder. We use functional Renormalisation Group methods, which prove, here, scheme-dependant. In the superconducting phase, the binding/antibinding gap is stabilized, but in the antiferromagnetic phase, it shrinks and the ladder turns one-dimensional.

Abramovici, G; Abramovici, Gilles; H\\'{e}ritier, Michel

2007-01-01

219

Drop Traffic in Microfluidic Ladder Networks with Fore-Aft Structural Asymmetry  

OpenAIRE

We investigate the dynamics of pairs of drops in microfluidic ladder networks with slanted bypasses, which break the fore-aft structural symmetry. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative drop spacing, enabling them to contract, synchronize, expand, or even flip at the ladder exit. Our experiments confirm all these behaviors predicted by theory. Numer...

Maddala, Jeevan; Wang, William S.; Vanapalli, Siva A.; Rengaswamy, Raghunathan

2011-01-01

220

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

OpenAIRE

The PLUME (Pixelated Ladder with Ultra-Low Material Embedding) Collaboration is developing ultra-light ladders for the vertex detector for a future linear collider. The double-sided ladder will integrate the sensors, readout infrastructure and mechanical supports with the aim of total material budget of 0.3% of radiation length. The requirement of as light as possible construction is driven by physics, in particular by measurements requiring determination of the quark charge sign. The first p...

Nomerotski, A.; Bachynska, O.; Baudot, J.; Chon-sen, N.; Claus, G.; Masi, R.; Deveaux, M.; Dulinski, W.; Gauld, R.; Goffe, M.; Goldstein, J.; Gregor, I-m; Hu-guo, C.; Imhoff, M.; Koetz, U.

2011-01-01

221

Drop Traffic in Microfluidic Ladder Networks with Fore-Aft Structural Asymmetry  

CERN Document Server

We investigate the dynamics of pairs of drops in microfluidic ladder networks with slanted bypasses, which break the fore-aft structural symmetry. Our analytical results indicate that unlike symmetric ladder networks, structural asymmetry introduced by a single slanted bypass can be used to modulate the relative drop spacing, enabling them to contract, synchronize, expand, or even flip at the ladder exit. Our experiments confirm all these behaviors predicted by theory. Numerical analysis further shows that while ladder networks containing several identical bypasses are limited to nearly linear transformation of input delay between drops, mixed combination of bypasses can cause significant non-linear transformation enabling coding and decoding of input delays.

Maddala, Jeevan; Vanapalli, Siva A; Rengaswamy, Raghunathan

2011-01-01

222

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

CERN Document Server

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

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

2010-01-01

223

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

Science.gov (United States)

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

224

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.

225

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

226

Fish Allergy  

Science.gov (United States)

... the skin and bones of fish. Although fish oil does not contain protein from the fish from ... Programs Food Allergy Awareness Week Teal Pumpkin Project Discovery Documentary School Poster Donation Stay Informed Newsletters FARE ...

227

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 ...

228

Walla Walla River Fish Passage Operations Program, 2000-2001 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 migration conditions in the basin. The migration concerns are being addressed by removing diversion structures, constructing fish passage facilities, implementing minimum instream flow measures, 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 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 2000-2001 project year, there were 624 summer steelhead (Oncorhynchus mykiss), 24 bull trout (Salvelinus confluentus), and 47 spring chinook (O. tshawytscha) counted at the Nursery Bridge Dam adult trap between December 27, 2000 and June 7, 2001. The Little Walla Walla River juvenile trap was not operated this year. The project transported 1600 adult spring chinook from Ringold Springs Hatchery to the South Fork Walla Walla Brood Holding Facility and outplanted 1156 for natural spawning in the basin. The project also provided equipment for transportation of juveniles captured during the construction fish salvage at Nursery Bridge Dam.

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

2004-02-01

229

Performance of Long Ladder for the LHCb Silicon Tracker  

CERN Document Server

The LHCb Silicon Tracker uses detector ladders with readout strips with an effective length of up to 36cm. Kapton interconnect cables of up to 54cm in length are employed in between silicon sensors and front-end readout hybrids. Fast front-end readout electronic with a shaping time of around 25ns are employed to avoid pile-up of events from consectutive LHC bunch crossings. An extensive measurement program as well as simulations have been carried out to study the expected noise performance of these detectors.

Steinkamp, Olaf

2005-01-01

230

Two-loop ladder diagram contributions to Bhabha scattering. II  

International Nuclear Information System (INIS)

The authors determine the dominant contribution to the Bhabha scattering amplitudes arising from the six two-loop ladder-like diagrams in the limit s>>t>>m2>>?2, where ? is the photon mass. A method is developed that allows for the simultaneous presence of these four different scales. While each individual diagram contributes four logarithmic factors to the amplitude, the two leading orders cancel, leaving only two such factors in the sum. They are precisely the logarithmic terms associated with two infrared photons. Integrals are also given for the terms that could possibly give single logarithms, but their sum is expected to vanish. 9 refs

231

Twisted-order parameter applied to dimerized ladders  

International Nuclear Information System (INIS)

We apply the twisted-order parameter (TOP) for dimerized quantum spin ladders to locate the critical points that separate gapped phases representing quantum spin liquids of various types. Using the density matrix renormalization group (DMRG), method, we find that the TOP is a good order parameter for these systems regardless of the number of legs. As a check, we reproduce with the DMRG and periodic boundary conditions the computations previously done with quantum Monte Carlo for one-dimensional S = 1/2, S = 1, S = 3/2 and S = 2 Heisenberg chains with alternating bonds

232

Azygos ladder and looped thoracic duct – a case report  

Directory of Open Access Journals (Sweden)

Full Text Available Knowledge of variations in the posterior mediastinum close to the vertebral column is important for cardiothoracic surgeons, radiologists and orthopedic surgeons. We report variations of azygos veins and thoracic duct. The azygos system of veins showed a ladder pattern. The hemiazygos and accessory hemiazygos veins communicated with the azygos vein through six transverse channels across the vertebral column. The accessory hemiazygos and hemiazygos veins joined to form a common channel which opened into the azygos vein. The thoracic duct gave two branches in the posterior mediastinum and these branches joined to form a loop.

Kumar N

2011-04-01

233

Optimal molecular alignment and orientation through rotational ladder climbing  

Science.gov (United States)

We study the control by electromagnetic fields of molecular alignment and orientation in a linear, rigid-rotor model. With the help of a monotonically convergent algorithm, we find that the optimal field is in the microwave part of the spectrum and acts by resonantly exciting the rotation of the molecule progressively from the ground state, i.e., by rotational ladder climbing. This mechanism is present not only when maximizing orientation or alignment, but also when using prescribed target states that simultaneously optimize the efficiency of orientation/alignment and its duration. The extension of the optimization method to consider a finite rotational temperature is also presented.

Salomon, Julien; Dion, Claude M.; Turinici, Gabriel

2005-10-01

234

Optimal molecular alignment and orientation through rotational ladder climbing  

CERN Document Server

We study the control by electromagnetic fields of molecular alignment and orientation, in a linear, rigid rotor model. With the help of a monotonically convergent algorithm, we find that the optimal field is in the microwave part of the spectrum and acts by resonantly exciting the rotation of the molecule progressively from the ground state, i.e., by rotational ladder climbing. This mechanism is present not only when maximizing orientation or alignment, but also when using prescribed target states that simultaneously optimize the efficiency of orientation/alignment and its duration.

Salomon, J; Turinici, G; Salomon, Julien; Dion, Claude M.; Turinici, Gabriel

2005-01-01

235

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

236

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.

237

Phase Diagram of the Spin Ladder with Four Spin exchange  

Science.gov (United States)

The increasing evidence for four spin interactions in the undoped High-Tc compounds such as LaCu_2O4 sparks new interest in the phase diagram of spin systems with four spin exchange. With numerical techniques such as Exact Diagonalization and DMRG we explore the phase diagram of the two leg spin ladder with additional cyclic exchange and attempt to characterize the dominant correlations. We find gapless phases where the spin-spin correlations are strongest and others where the twist or vector chirality correlations are strongest. Preliminary results on the phase diagram of the two dimensional Heisenberg model with four spin interaction will also be presented.

Läuchli, Andreas; Troyer, Matthias

2002-03-01

238

Phase diagram of the Heisenberg spin ladder with ring exchange  

Science.gov (United States)

We investigate the phase diagram of a generalized spin-1/2 quantum antiferromagnet on a ladder with rung, leg, diagonal, and ring-exchange interactions. We consider the exactly soluble models associated with the problem, obtain the exact ground states which exist for certain parameter regimes, and apply a variety of perturbative techniques in the regime of strong ring-exchange coupling. By combining these approaches with considerations related to the discrete Z4 symmetry of the model, we present the complete phase diagram.

Gritsev, V.; Normand, B.; Baeriswyl, D.

2004-03-01

239

Phase Diagram of the Heisenberg Spin Ladder with Ring Exchange  

CERN Document Server

We investigate the phase diagram of a generalized spin-1/2 quantum antiferromagnet on a ladder with rung, leg, diagonal, and ring-exchange interactions. We consider the exactly soluble models associated with the problem, obtain the exact ground states which exist for certain parameter regimes, and apply a variety of perturbative techniques in the regime of strong ring-exchange coupling. By combining these approaches with considerations related to the discrete Z_4 symmetry of the model, we present the complete phase diagram.

Gritsev, V; Baeriswyl, D

2004-01-01

240

Specific heat of spin-one-half frustrated Heisenberg ladder  

Science.gov (United States)

The specific heat of S=1/2 frustrated Heisenberg antiferromagnetic spin ladder is investigated by means of a modified spin-wave theory. It is found that at low temperatures the specific heat shows a round peak, and decays exponentially below the peak temperature. The maximum of the specific heat decreases with increasing the rung-couplings, while it increases with increasing the diagonal couplings. The peak temperature moves to lower temperatures when the rung-coupling is increased, while it shifts to higher temperatures when the diagonal coupling is increased. Our observation is expected to be confirmed experimentally.

Su, Gang; Xing, Huaizhong; Wang, Jianbo; Li, Fashen

2001-05-01

241

The QCD gluon ladders and HERA structure function  

CERN Document Server

We report on the extension of the data fitting considering the QCD inspired model based on the summation of gluon ladders applied to the $ep$ scattering. In lines of a two Pomeron approach, the structure function $F_2$ has a hard piece given by the model and the remaining soft contribution: a soft Pomeron and non-singlet content. In this contribution, we carefully estimate the relative role of the hard and the soft pieces from a global fit in a large span of $x$ and $Q^2$.

Lengyel, A I

2002-01-01

242

Perspectives on fish impingement  

International Nuclear Information System (INIS)

Data on fish impingement and related parameters are being gathered at a large number of power stations throughout the country at substantial monetary and manpower costs. A national survey of fish impingement at power plants was conducted and much of the information compiled in a standardized format--an effort that we think will aid in planning improvements in the design, siting, and operation of the cooling-water intakes. This paper examines the objectives of the fish impingement studies, monitoring programs, variables affecting fish impingement, siting and design criteria, state-of-the-art of screening systems, and suggestions for meeting 316(b) requirements. It also discusses where the emphasis should be placed in future fish-impingement related activities

243

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

Science.gov (United States)

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

Ucak, C.

2009-01-01

244

Shaping Career Ladder Reform: The Influence of Teachers on the Policymaking Process.  

Science.gov (United States)

Although teachers are a prime target of state reform agendas, recent research suggests that teachers are also major sources of influence on career ladders, an expensive and controversial reform. Assessment of Utah career ladder reform indicates that a 1983 Utah Reform Committee proposal aimed at differentiating salaries, creating hierarchical…

Malen, Betty; Hart, Ann Weaver

245

A Teacher-Professor Partnership Model for Career Ladder Assessment and Growth.  

Science.gov (United States)

This paper discusses a career ladder plan developed by the Clayton (Missouri) School District and the teacher assessment procedure developed to implement that plan. The basics of the plan include (1) a 20-step basic salary schedule, (2) a system of incentives and rewards available to each teacher at each stage of the career ladder, and (3) an…

Brown, Doris M.; Morrison, Marilyn

246

Carrer Ladder Reform: A Multi-Level Analysis of Initial Efforts.  

Science.gov (United States)

Interpretation, assimilation, and adjustment to the Utah Career Ladder Program and the extent to which these responses reflect fundamental changes in the structure of teacher work were assessed. Promotional positions and differentiated salaries--distinctive features of a career ladder--were being compromised at all levels of the system. (SLD)

Malen, Betty; Hart, Ann Weaver

1987-01-01

247

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

Energy Technology Data Exchange (ETDEWEB)

A partially ladder-type polymer was synthesized, where the ladder-type planar structure was prepared using BBr{sub 3}-promoted cyclization and alkylated thiophene was used as a soluble derivative. The relatively small band gap and broad absorption band, in addition to the crystallinity, make this polymer an attractive material for use in a variety of optoelectronic applications. The rigid coplanar structures of such polymers provide resistance to deformation and enhanced ?-conjugation, which result in a number of desirable properties, such as intense luminescence, high carrier mobility, and environmental stability. Most studies in this field have focused on poly(p-phenylene)-based polymers, including both step ladder-type or fully ladder-type poly(phenylene)s. However, the commercial exploitation of ladder poly(phenylene) homopolymers has been hampered by their intractable nature.

Lee, Myunggun; Hahn, Sojung; Kim, Taehyun [Incheon National Univ., Incheon (Korea, Republic of)

2013-08-15

248

Transgenic Fish  

Science.gov (United States)

Fish into which foreign DNA is artificially introduced and integrated into their genome are called transgenic fish. Since the development of the first transgenic fish in 1985, techniques to produce transgenic fish have improved tremendously, resulting in the production of genetically modified (GM) ...

249

Geometrically frustrated honeycomb and ladder lattices of nanoscale ferromagnetic islands  

Science.gov (United States)

We have studied arrays of interacting single-domain ferromagnetic islands which are arranged on lattices such that the interactions between the islands are frustrated by the geometry of the arrays. While previous studies in our group [1] have focused on a frustrated square lattice, we now report results on lattices with the honeycomb geometry and with a topologically equivalent ladder geometry in which the islands meet in vertices of three islands. Each permalloy island measures approximately 80nm by 220nm with a thickness 25nm, and is evenly spaced with lattice spacing ranging from 225nm to 425nm for honeycomb lattice and from 320nm to 880nm for ladder lattice. Magnetic force microscopy measurements of the arrays after demagnetization demonstrate that the interactions between the islands are frustrated and that the correlations between islands decrease with increasing spacing of the islands. A detailed analysis of the correlations between the islands will be presented. This research has been supported by the Army Research Office. [1] R. F. Wang, C. Nisoli, R. S. Freitas, J. Li, W. McConville, B. J. Cooley, M. S. Lund, N. Samarth, C. Leighton, V. H. Crespi, and P. Schiffer, Nature 439, 303 (2006).

Li, Jie; Ke, Xianglin; Wang, Ruifang; McConville, William; Nisoli, Cristiano; Lammert, Paul; Crespi, Vincent; Schiffer, Peter

2007-03-01

250

Slow magnetic relaxation in lanthanide ladder type coordination polymers.  

Science.gov (United States)

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

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

2014-01-28

251

A study of stark ladders via an evolution operator  

International Nuclear Information System (INIS)

Using an evolution operator reported earlier, the nature of energy spectrum of Bloch electrons in external electric field is studied and the circumstances under which stark ladders would exist are examined. At first a general expression for the energy spectrum is obtained. Then it is shown that the energy spectrum would correspond to an exact stark ladder provided the electric field is considered only upto first order. If the electric field is retained beyond first order, one obtains corrections to the stark levels corresponding to first order field. These correction terms are k- dependent and involve zener tunneling beyond first order. Small in magnitude, they produce a slight broadening of the first order stark levels. The exact forms of these correction terms are rather formidable; to exemplify, the form of 2nd order correction terms is shown. It is discussed briefly how the evolution operator of reference can be generalised to include the presence of optical field and thereby information regarding transitions depending on zener tunneling and optical absorption can be obtained. (author)

252

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

253

Diagonal ladders: A class of models for strongly coupled electron systems  

OpenAIRE

We introduce a class of models defined on ladders with a diagonal structure generated by np plaquettes. The case np=1 corresponds to the necklace ladder and has remarkable properties that are studied using density matrix renormalization-group and recurrent variational ansatzes. The antiferromagnetic Heisenberg (AFH) model on this ladder is equivalent to the alternating spin-1/spin-1/2 AFH chain, which is known to have a ferromagnetic ground state (GS). For doping 1/3 the GS is a fully doped (...

Sierra, Germa?n; Marti?n-delgado, Miguel A?ngel; White, S. R.; Scalapino, D. J.; Dukelsky, Jorge

1999-01-01

254

Performance of Long Ladders for the LHCb Silicon Tracker  

CERN Document Server

The LHCb Silicon Tracker uses detector ladders with readout strips with an effective length of up to 36,cm. Kapton interconnect cables of up to 54,cm in length are employed in between silicon sensors and front-end readout hybrids. Fast front-end readout electronics with a shaping time of around 25,ns are employed to avoid pile-up of events from consecutive LHC bunch crossings. An extensive measurement program as well as simulations have been carried out to study the expected noise performance of these detectors. Presented at the 14th International Workshop on Vertex Detectors, Chuzenji Lake, Nikko, Japan, November 7-11, 2005 Proceedings submitted for publication in Nucl. Instr. and Meth. A

Agari, M; Blouw, J; Hofmann, W; Knöpfle, K T; Löchner, S; Maciuc, F; Schmelling, M; Smale, N J; Schwingenheuer, B; Voss, H; Pugatch, V; Pylypchenko, Y; Bay, A; Bettler, M O; Carron, B; Fauland, P; Frei, R; Jiménez-Otero, S; Nicolas, L; Perrin, A; Schneider, O; Tran, MT; Van Hunen, J J; Vervink, K; Vollhardt, A; Adeva, B; Esperante-Pereira, D; Lois, C; Pérez-Trigo, E; Pló-Casasus, M; Vázquez, P; Bernhard, R P; Bernet, R; Gassner, J; Köstner, S; Lehner, F; Needham, M; Sakhelashvili, T M; Steiner, S; Steinkamp, O; Straumann, U; Volyanskyy, D; Wenger, A

2005-01-01

255

The power of engagement: implementation of a career ladder program.  

Science.gov (United States)

At Baystate Health in Massachusetts, the development and implementation of a career ladder program was implemented to reduce turnover and to improve employee satisfaction, morale, and recruitment efforts. There was significant initial expenditure in the program, as a result of promoting the large number of employees with significant experience and seniority. A smaller number of staff are expected to apply for advancement during successive cycles, allowing for decreased incremental expense going forward. Critical to the success of the program was understanding the time commitment, getting senior organizational support and staff buy-in, and justifying the associated expenses. The development and initiation of the program has done much to support a positive work environment with increased morale and higher performance among significant numbers of staff at all levels. PMID:22514970

Bourgeault, Robert; Newmark, Jason

2012-01-01

256

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

257

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

258

Topological phases of the two-leg Kitaev ladder  

Energy Technology Data Exchange (ETDEWEB)

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 Z{sub 2} from an integer Z. These observations are consistent with a recent general study [S. Tewari, J.D. Sau, (arXiv:1111.6592v2)].

Wu, Ning, E-mail: wun1985@gmail.com [Department of Physics, Tsinghua University, Beijing 100084 (China)

2012-10-15

259

Phase diagram of the frustrated two-leg ladder model  

Science.gov (United States)

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

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

2001-04-01

260

Groundstate Properties of Frustrated Spin Systems on a Ladder  

Science.gov (United States)

A spin-1/2 Heisenberg model on a ladder,which consists of one ferromagnetic leg and one antiferromagnetic legconnected by antiferromagnetic rungs, is discussed.The phase transition in the groundstate is investigated in such a system.It is shown that the spontaneous magnetization, m, becomes zeroif the interchain coupling R is larger than a critical value R c.It is found that R c=1.134461 ±0.000001 by the exact diagonalization.In the region R

Tsukano, Masayoshi; Takahashi, Minoru

1997-04-01

261

Chutes and ladders in hepatitis C nucleoside drug development.  

Science.gov (United States)

Chutes and Ladders is an exciting up-and-down-again game in which players race to be the first to the top of the board. Along the way, they will find ladders to help them advance, and chutes that will cause them to move backwards. The development of nucleoside analogs for clinical treatment of hepatitis C presents a similar scenario in which taking shortcuts may help quickly advance a program, but there is always a tremendous risk of being sent backwards as one competes for the finish line. In recent years the treatment options for chronic hepatitis C virus (HCV) infection have expand due to the development of a replicon based in vitro evaluation system, allowing for the identification of multiple drugable viral targets along with a concerted and substantial drug discovery effort. Three major drug targets have reached clinical study for chronic HCV infection: the NS3/4A serine protease, the large phosphoprotein NS5A, and the NS5B RNA-dependent RNA polymerase. Recently, two oral HCV protease inhibitors were approved by the FDA and were the first direct acting anti-HCV agents to result from the substantial research in this area. There are currently many new chemical entities from several different target classes that are being evaluated worldwide in clinical trials for their effectiveness at achieving a sustained virologic response (SVR) (Pham et al., 2004; Radkowski et al., 2005). Clearly the goal is to develop therapies leading to a cure that are safe, widely accessible and available, and effective against all HCV genotypes (GT), and all stages of the disease. Nucleoside analogs that target the HCV NS5B polymerase that have reached human clinical trials is the focus of this review as they have demonstrated significant advantages in the clinic with broader activity against the various HCV GT and a higher barrier to the development of resistant viruses when compared to all other classes of HCV inhibitors. PMID:24275341

Coats, Steven J; Garnier-Amblard, Ethel C; Amblard, Franck; Ehteshami, Maryam; Amiralaei, Sheida; Zhang, Hongwang; Zhou, Longhu; Boucle, Sebastien R L; Lu, Xiao; Bondada, Lavanya; Shelton, Jadd R; Li, Hao; Liu, Peng; Li, Chengwei; Cho, Jong Hyun; Chavre, Satish N; Zhou, Shaoman; Mathew, Judy; Schinazi, Raymond F

2014-02-01

262

Chutes and Ladders in Hepatitis C Nucleoside Drug Development§  

Science.gov (United States)

Chutes and Ladders is an exciting up-and-down-again game in which players race to be the first to the top of the board. Along the way, they will find ladders to help them advance, and chutes that will cause them to move backwards. The development of nucleoside analogs for clinical treatment of hepatitis C presents a similar scenario in which taking shortcuts may help quickly advance a program, but there is always a tremendous risk of being sent backwards as one competes for the finish line. In recent years the treatment options for chronic hepatitis C virus (HCV) infection have expand due to the development of a replicon based in vitro evaluation system, allowing for the identification of multiple drugable viral targets along with a concerted and substantial drug discovery effort. Three major drug targets have reached clinical study for chronic HCV infection: the NS3/4A serine protease, the large phosphoprotein NS5A, and the NS5B RNA-dependent RNA polymerase. Recently, two oral HCV protease inhibitors were approved by the FDA and were the first direct acting anti-HCV agents to result from the substantial research in this area. There are currently many new chemical entities from several different target classes that are being evaluated worldwide in clinical trials for their effectiveness at achieving a sustained virologic response (SVR) (Pham et al., 2004; Radkowski et al., 2005). Clearly the goal is to develop therapies leading to a cure that are safe, widely accessible and available, and effective against all HCV genotypes (GT), and all stages of the disease. Nucleoside analogs that target the HCV NS5B polymerase that have reached human clinical trials is the focus of this review as they have demonstrated significant advantages in the clinic with broader activity against the various HCV GT and a higher barrier to the development of resistant viruses when compared to all other classes of HCV inhibitors. PMID:24275341

Coats, Steven J.; Garnier-Amblard, Ethel C.; Amblard, Franck; Ehteshami, Maryam; Amiralaei, Sheida; Zhang, Hongwang; Zhou, Longhu; Boucle, Sebastien R. L.; Lu, Xiao; Bondada, Lavanya; Shelton, Jadd R.; Li, Hao; Liu, Peng; Li, Chengwei; Cho, Jong Hyun; Chavre, Satish N.; Zhou, Shaoman; Mathew, Judy; Schinazi, Raymond F.

2014-01-01

263

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 ...

264

Evaluate effects of hydraulic turbulence on the survival of migratory fish: design and construction of experimental apparatus to study the potential effects of turbulence on fish; TOPICAL  

International Nuclear Information System (INIS)

This report presents the completed design and construction process, and working details, of the test apparatus for the turbulence project. As mentioned in the first progress report, this type of experiment has not been attempted previously. In addition, turbulence data in the tailrace of a power plant are not available for reference. We plan to generate turbulence intensities and scale based on representative flow velocities downstream of draft tubes as well as visual observations of flow conditions in a typical tailrace area. Various combinations of nozzles will be used to generate mixing inside a large tank cavity, referred to herein as the turbulence chamber. The turbulence chamber was made with steel frame and clear acrylic sides and bottom. The clear sides and bottom will facilitate viewing and videotaping from outside. Nozzle velocities and water surface profiles will be accurately monitored with calibrated flow measurement devices to insure repeatability of the hydraulic conditions during biological testing

265

Fatherly Fish  

Science.gov (United States)

In the hit movie Finding Nemo, Marlin the clown fish searches the ocean for his missing son. While it's unlikely that a real clown fish could make this long journey, some male fish do show a fatherly attitude toward their offspring. You'll hear about one in this Science Update.

Science Update

2003-10-13

266

Fish forms  

Science.gov (United States)

In this activity, learners create a three-dimensional sculpture while examining the characteristics of fish. Learners use clay and other craft supplies to model a fish's body, fins, scales, eyes, gills, and mouth. Then learners will discuss the function of each part and how fish differ amongst each other.

2012-06-26

267

75 FR 56986 - Endangered and Threatened Species; Take of Anadromous Fish  

Science.gov (United States)

...River Inter-Tribal Fish Commission (CRITFC...designed to determine the fishes' freshwater movements and how those...Creeks, Washington. The fish would be captured using...on fish abundance and distribution; (2) determine...

2010-09-17

268

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

269

Superexchange in the quarter- filled two- leg ladder system NaV2O5  

CERN Document Server

A theory of superexchange in the mixed valent layer compound NaV2O5 is presented which provides a consistent description of exchange both in the disordered and charge ordered state. Starting from results of band structure calculations for NaV2O5 first an underlying electronic model for a ladder unit in the Trellis lattice is formulated. By using the molecular orbital representation for intra-rung electronic states a second-order perturbation procedure is developed and an effective spin-chain model for a ladder is derived. Variation of the resulting superexchange integral J is examined numerically as the ladder system evolves from a charge disordered to the extreme ('zig-zag') charge ordered state. It is found that the effective intra- ladder superexchange is always antiferromagnetic.

Yushankhai, V Yu

2001-01-01

270

Resonant two-magnon Raman scattering in two-dimensional and ladder-type Mott insulators  

CERN Document Server

We investigate the resonant two-magnon Raman scattering in the two-dimensional (2D) and ladder-type Mott insulators by using a half-filled Hubbard model in the strong coupling limit. By performing numerical diagonalization calculations for small clusters, we find that the model can reproduce the experimental features in the 2D that the Raman intensity is enhanced when the incoming photon energy is not near the absorption edge but well above it. In the ladder-type Mott insulators, the Raman intensity is found to resonate with absorption spectrum in contrast to the 2D system. The difference between 2D and the ladder systems is explained by taking into account the fact that the ground state in 2D is a spin-ordered state while that in ladder is a spin-gapped one.

Onodera, H; Maekawa, S; Onodera, Hiroaki; Tohyama, Takami; Maekawa, Sadamichi

2002-01-01

271

77 FR 15839 - Culturally Significant Objects Imported for Exhibition Determinations: “Joan Miró: the Ladder of...  

Science.gov (United States)

...Culturally Significant Objects Imported for Exhibition Determinations: ``Joan Mir[oacute...that the objects to be included in the exhibition ``Joan Mir[oacute]: the Ladder...imported from abroad for temporary exhibition within the United States, are of...

2012-03-16

272

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.

California Academy of Sciences

2008-01-01

273

Molecular design of Cy3 derivative for highly sensitive in-stem molecular beacon and its application to the wash-free FISH.  

Science.gov (United States)

We herein describe a novel in-stem molecular beacon (ISMB) containing multiple Cy3-quencher pairs on d-threoninol scaffolds in the stem region. The designed Cy3 derivative was not significantly quenched by the adjacent nucleobases, self-quenching of the fluorophore was minimal, and the fluorophore did not severely destabilize the duplex. Using newly designed Cy3, we synthesized ISMBs containing two Cy3 moieties. The signal to background ratio of the ISMB containing two Cy3 moieties was above 100, whereas that with one Cy3 was 30. A Cy3-derivative containing ISMB used in a fluorescence in situ hybridization (FISH) detected endogenous ?-actin mRNA in fixed cells without need for washing procedures. PMID:25769519

Kashida, Hiromu; Osawa, Takuya; Morimoto, Kazuhiro; Kamiya, Yukiko; Asanuma, Hiroyuki

2015-04-15

274

Magnetic Excitations of Coupled Spin Ladders: a Quantum Monte Carlo Study  

OpenAIRE

We calculate the magnetic excitation spectrum in the stripe phase of high-T_c materials. The stripes are modeled as coupled spin-1/2 ladders and the spin dynamics is extracted using Quantum Monte Carlo (QMC) simulations, which can capture the strong quantum fluctuations near quantum critical points of coupled spin ladders. We find a characteristic hourglass magnetic excitation spectrum with high-energy peaks rotated by 45 degrees compared to the incommensurate low-energy pea...

Andersen, Brian M.; Syljuasen, Olav F.

2006-01-01

275

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

OpenAIRE

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

Ayca Kangal

2013-01-01

276

The Marijuana Ladder: Measuring motivation to change marijuana use in incarcerated adolescents  

OpenAIRE

The purpose of this study was to determine if a modified version of the Contemplation Ladder, a measure of motivation to change marijuana use among incarcerated adolescents (Marijuana Ladder; ML), was related to marijuana use and treatment engagement. Participants (N = 122) in this study were all incarcerated at a state juvenile correctional facility in the Northeast. Adolescents were assessed at the beginning of their incarceration, 2 months into their incarceration, and 3 months after their...

Slavet, James D.; Stein, L. A. R.; Colby, Suzanne M.; Barnett, Nancy P.; Monti, Peter M.; Golembeske, Charles; Lebeau-craven, Rebecca

2005-01-01

277

Bethe-Salpeter equation in Minkowski space with cross-ladder kernel  

International Nuclear Information System (INIS)

A new method for solving the Bethe-Salpeter equation is developed. It allows to find the Bethe-Salpeter amplitudes both in Minkowski and in Euclidean spaces and, as a by product, the light-front wave function. The method is valid for any kernel given by irreducible Feynman graphs. Bethe-Salpeter and Light-Front equations for scalar particles with ladder + cross-ladder kernel are solved

278

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

279

Ladder and Lambda systems electromagnetically induced transparency in thin and extremely-thin cells  

International Nuclear Information System (INIS)

Full text: The recent interest in the effect of electromagnetically induced transparency (EIT) phenomenon is caused by a number of important applications. We study the possibility for miniaturization of alkali cells for application in the EIT experiments without compromising the EIT resonance parameters. We present results on an EIT ladder system of the 85Rb, 87Rb, 5S-5P-nD(mS) transitions with n = 5 as well as involving highly excited Rydberg states with n = 26 and m = 48. For this purpose a recently developed multi-region (MR) high temperature cell containing Rb vapor has been used. The construction of MR cell allows us to study EIT effect in atomic vapor of thickness L= 4 mm, 2 mm, and 0.5 - 6 ?m. The design of MR cells with length L in the range of 30 nm - 10 mm will be presented. It is demonstrated that in 4 mm and 2 mm-long cells it is possible to realize a robust formation of EIT resonance in counter-propagating geometry with a high contrast (50 - 60 %) and with a sub-natural linewidth. The fine structure of 26 D5/3, 3/2 has been measured. For 5S-5P-48S system a pronounced Stark broadening of the EIT resonance is observed. The short thickness of the cell allows one to provide a tight focusing to achieve high intensity. Under this condition efficient 2-photon absorption has been detected, even when the thickness L is reduced to 6 ?m. We present experimental and theoretical results on an EIT ladder system of the lts on an EIT ladder system of the 85Rb, 87Rb, 5S-5P-5D for a pure Rb vapour column with L of the order of light wavelength (? = 780 nm) and varying in the range of (0.75 to 6) ?. It is shown that in the case when coupling laser frequency is resonant with atomic transition the linewidth of the EIT resonance (6 to 8 MHz) is weakly dependent on the thickness as ? L-0.25. The explanation is that the contribution of atoms with small velocity projection in the laser radiation direction (i.e. atoms flying nearly parallel to the cell windows) is enhanced thanks to their longer interaction time with laser field. Due to this atomic velocity selectivity, the observed linewidth of the EIT resonance is more than by an order narrower than that expected from the inverse of the window-to-window flight time of the atoms. Meanwhile, direct influence of atom-wall collisions on the EIT resonance is well seen when there is a large detuning of the coupling laser with respect to resonance transition (EIT linewidth for this case achieves ? 100 MHz). The slight dependence of the EIT linewidth for the case when coupling frequency is resonant with atomic transition allows us to detect EIT resonance (< 20 MHz) at the smallest thickness reported up to now L= 0.75 ? = 585 nm. (author)

280

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

Directory of Open Access Journals (Sweden)

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

Mostafa M. Gomaa

2011-02-01

281

Topological phase transition in the extended cluster compass ladder  

Science.gov (United States)

We have studied the exact solution of the extended cluster compass ladder, which is equivalent to the extended quantum compass model with cluster interaction between next-nearest-neighbor spins, by using the Jordan-Wigner transformation. We show that this model is always gapful except at the critical surfaces where the energy gap disappears. We obtain the analytic expressions of all critical couplings which drive quantum phase transitions. This model shows a rich phase diagram which includes spin-flop, strip antiferromagnetic, and topological ordered on the legs, in addition to the phase with antiparallel ordering of the spin y component on the rungs. We also study the universality and scaling properties of the three point correlation function derivatives in different regions to confirm the results obtained using the energy gap analysis. On the other hand, we have replaced the cluster interaction with the usual form and using the Lanczos method a numerical experiment is done. Analyzing the numerical results, we show that the effect of the cluster interaction between next-nearest-neighbor spins is completely different from the usual form.

Jafari, R.; Mahdavifar, S.

2014-04-01

282

HST/WFC3 flux calibration ladder: Vega  

Science.gov (United States)

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

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

2014-08-01

283

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)

284

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.

285

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.

Jonathan Bird Productions

2010-08-10

286

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

287

36 CFR 2.3 - Fishing.  

Science.gov (United States)

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

2010-07-01

288

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

289

Synthesis and characterization of functional ladder-like polysilsesquioxane and their hybrid films with polyimide  

Energy Technology Data Exchange (ETDEWEB)

Ladder-like polyphenylsilsesquioxane has been synthesized by a convenient two-step approach and then modified to ladder-like poly(nitrophenyl)silsesquioxane (LPNPSQ) and poly(aminophenyl)silsesquioxane (LPAPSQ) by nitration and reduction reaction. These ladder-like polysilsesquioxanes (LPSQs) were characterized by Fourier transform infrared, nuclear magnetic resonance and X-ray diffraction (XRD). The results confirm the ladder-like structures of LPSQs and suggest the decrease of regularity after the chemical modification. Then high performance polyimide/ladder-like polysilsesquioxane (PI/LPSQ) hybrid films have been prepared by incorporating synthetic LPSQs with different functional groups into PI matrix, respectively, using conventional techniques. The interfacial interactions between PI matrix and LPSQ were investigated with XRD and scanning electron microscopy. Then the thermal and mechanical properties of the hybrid films were studied using dynamic mechanical analysis and tensile tests. The results indicate that different functional groups in LPSQs have great effects on the interfacial interactions and the properties of the hybrids. Both LPNPSQ and LPAPSQ can be dispersed uniformly in PI matrix because of the physical or chemical interaction between functional groups and PI. With these strong interfacial interactions, PI/LPNPSQ and PI/LPAPSQ hybrid films show higher glass transition temperatures and better mechanical properties.

Gao Qiushuang; Qi Shengli; Wu Zhanpeng; Wu Dezhen, E-mail: wdz@mail.buct.edu.cn; Yang Wantai

2011-07-29

290

Diagonal ladders: A class of models for strongly coupled electron systems  

Science.gov (United States)

We introduce a class of models defined on ladders with a diagonal structure generated by np plaquettes. The case np=1 corresponds to the necklace ladder and has remarkable properties that are studied using density matrix renormalization-group and recurrent variational ansatzes. The antiferromagnetic Heisenberg (AFH) model on this ladder is equivalent to the alternating spin-1/spin-12 AFH chain, which is known to have a ferromagnetic ground state (GS). For doping 1/3 the GS is a fully doped (1,1) stripe with the holes located mostly along the principal diagonal while the minor diagonals are occupied by spin singlets. This state can be seen as a Mott insulator of localized Cooper pairs on the plaquettes. A physical picture of our results is provided by a tp-Jp-td model of plaquettes coupled diagonally with a hopping parameter td. In the limit td-->? we recover the original t-J model on the necklace ladder while for a weak hopping parameter the model is easily solvable. The GS in the strong hopping regime is essentially an ``on link'' Gutzwiller projection of the weak hopping GS. We generalize the tp-Jp-td model to diagonal ladders with np>1 and the two-dimensional square lattice. We use in our construction concepts familiar in statistical mechanics such as medial graphs and Bratelli diagrams.

Sierra, G.; Martín-Delgado, M. A.; White, S. R.; Scalapino, D. J.; Dukelsky, J.

1999-03-01

291

Hood River Pelton Ladder evaluation studies: Annual report 1995  

International Nuclear Information System (INIS)

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

292

Hood River Pelton Ladder evaluation studies: Annual report 1995; ANNUAL  

International Nuclear Information System (INIS)

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

293

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

294

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

295

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

296

Frustrated spin-1/2 two-leg and three-leg antiferromagnetic Heisenberg ladders  

Science.gov (United States)

The goal of this project is to study the ground-state properties of frustrated spin-1/2 two- and three-leg Heisenberg ladders, and to investigate possible effects of diagonal couplings on spin gaps. The ground-state and the first-excited-state energies of these two systems are calculated systematically by using the density matrix renormalization group method. The ground state phase diagrams for these two systems are obtained. For the frustrated two-leg ladder, we found that the spin gap is insensitive to the change of the FM diagonal coupling constant. This is in agreement with experimental suggestions. For the frustrated three-leg ladder, we conclusively proved that introducing AF diagonal couplings can not change the gapless property of the ground state.

Zhu, Ningsheng

2000-11-01

297

Numerical study of critical properties and hidden orders in dimerized spin ladders  

Science.gov (United States)

Dimerized antiferromagnetic spin-(1)/(2) ladders are known to exhibit a quantum critical phase transition in the ground state, the existence or absence of which is dependent on the dimerization pattern of the ladder. The gapped phases cannot be distinguished by the conventional Landau long-range order parameter. However, they possess a nonlocal (hidden) string-order parameter, which is nonzero in one phase and vanishes in the other. We use an exact diagonalization technique to calculate ground-state energies, energy gaps, and string-order parameters of dimerized two- and three-leg Heisenberg ladders, as well as a critical scaling analysis to yield estimates of the critical exponents ? and ?.

Gibson, Sandra J.; Meyer, R.; Chitov, Gennady Y.

2011-03-01

298

Evaluation of Juvenile Fish Bypass and Adult Fish Passage Facilities at Water Diversions on the Umatilla River; 1994 Annual Report.  

Energy Technology Data Exchange (ETDEWEB)

We report on our progress from October 1993 through September 1994 in evaluating juvenile salmonid bypass facilities and juvenile salmonid passage through ladder facilities, and investigating passage conditions for juvenile fish at diversion dam facilities on the lower Umatilla River in northeastern Oregon. We also report on our progress in evaluating adult salmonid passage at and between dams on the lower Umatilla River and upriver migration using radio telemetry. Two principal studies are also included. Report A (ODFW): To evaluate the juvenile salmonid bypass facilities a Feed and Furnish canals, juvenile salmonid passage through fish ladders at Stanfield, Feed Canal, Westland, and Three Mile Falls dams, and the juvenile salmonid trap and haul procedures at Westland Canal. To investigate passage conditions at all passage facilities. Report B (CTUIR): To examine the passage of adult salmonids past diversions in the lower Umatilla River and their movement in the upper river after transport, using radio telemetry, and to assess factors for successful homing. These studies are part of a program to rehabilitate anadromous fish stocks in the Umatilla River Basin, including restoration of coho salmon (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus tshawytscha), as well as enhancement of summer steelhead (Oncorhynchus mykiss).

Knapp, Suzanne M.

1995-01-01

299

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

300

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

International Nuclear Information System (INIS)

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

301

Phase diagram of frustrated mixed-spin ladders in the strong-coupling limit  

CERN Document Server

We study the ground-state properties of frustrated Heisenberg ferrimagnetic ladders with antiferromagnetic exchange interactions and two types of alternating sublattice spins. In the limit of strong rung couplings, we show that the mixed spin-1/2 and spin-1 ladders can be systematically mapped onto a spin-1/2 Heisenberg model. The system is either in a ferrimagnetic state or in a critical spin-liquid state depending on the competition between the spin exchanges along the legs and the diagonal exchanges.

Chen, S; Wang, Y; Chen, Shu; Wang, Li; Wang, Yupeng

2006-01-01

302

A simple case of d(x2-y2 pairing: Hubbard ladder  

Directory of Open Access Journals (Sweden)

Full Text Available We study the strength and the temperature scale of the d(x2-y2 pairing correlations in the Hubbard model on a ladder lattice using Quantum Monte Carlo (QMC simulations. In particular, we present QMC results on the particle-particle interaction and the solution of the Bethe-Salpeter equation for the d(x2-y2-wave BCS channel. These data show that there are strong d(x2-y2 pairing correlations in the Hubbard ladder for certain values of the model parameters.

Bulut N.

2012-03-01

303

"Ladder" structure in tonal noise generated by laminar flow around an airfoil.  

Science.gov (United States)

The presence of a "ladder" structure in the airfoil tonal noise was discovered in the 1970s, but its mechanism hitherto remains a subject of continual investigation in the research community. Based on the measured noise results and some numerical analysis presented in this letter, the variations of four types of airfoil tonal noise frequencies with the flow velocity were analyzed individually. The ladder structure is proposed to be caused by the acoustic/hydrodynamic frequency lag between the scattering of the boundary layer instability noise and the discrete noise produced by an aeroacoustic feedback loop. PMID:22713022

Chong, Tze Pei; Joseph, Phillip

2012-06-01

304

Optical absorption spectra in SrCu_2O_3 two-leg spin ladder  

OpenAIRE

We calculate the phonon-assisted optical-absorption spectra in SrCu_2O_3 two-leg spin-ladder systems. The results for two models proposed for SrCu_2O_3 are compared. In the model including the effects of a cyclic four-spin interaction, the shoulder structure appears at 978 cm^{-1} and the peak appears at 1975 cm^{-1} in the spectrum for polarization of the electric field parallel to the legs. In the other model which describes a pure two-leg ladder, the peak appears around t...

Haga, Nobuyasu; Suga, Sei-ichiro

2003-01-01

305

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

Directory of Open Access Journals (Sweden)

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

Paramita Dutta

2014-09-01

306

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

307

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

Science.gov (United States)

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; Maiti, Santanu K.; Karmakar, S. N.

2014-09-01

308

Calculation of tensor susceptibility beyond rainbow-ladder approximation of Dyson-Schwinger equations approach  

OpenAIRE

In this paper, we extend the calculation of tensor vacuum susceptibility in the rainbow-ladder approximation of the Dyson-Schwinger (DS) approach in [Y.M.Shi, K.P.Wu, W.M.Sun, H.S.Zong, J.L.Ping, Phys. Lett. B $\\bf{639}$, 248 (2006)] to that of employing the Ball-Chiu (BC) vertex. The dressing effect of the quark-gluon vertex on the tensor vacuum susceptibility is investigated. Our results show that compared with its rainbow-ladder approximation value, the tensor vacuum susc...

Shi, Yuan-mei; Zhu, Hui-xia; Sun, Wei-min; Zong, Hong-shi

2010-01-01

309

Scalar chiral order in spin ladders with four-spin exchanges  

International Nuclear Information System (INIS)

We show that scalar chiral order can be induced by four-spin exchanges in the two-leg spin ladder. By using the spin-chirality duality transformation, it is found that scalar-chiral-ordered states are exact ground states in a family of spin ladder models. In the scalar chiral phase, there is a finite energy gap above the doubly degenerate ground states. It is also shown that the SU(4)-symmetric model is on a multicritical point surrounded by the staggered dimer, staggered scalar chiral, and gapless phases

310

Spin-ladders with spin gaps: A description of a class of cuprates  

OpenAIRE

We investigate the magnetic properties of the Cu-O planes in stoichiometric Sr$_{n-1}$Cu$_{n+1}$O$_{2n}$ (n=3,5,7,...) which consist of CuO double chains periodically intergrown within the CuO$_2$ planes. The double chains break up the two-dimensional antiferromagnetic planes into Heisenberg spin ladders with $n_r=\\frac{1}{2}(n-1)$ rungs and $n_l=\\frac{1}{2}(n+1)$ legs and described by the usual antiferromagnetic coupling J inside each ladder and a weak and frustrated interl...

Gopalan, Sudha; Rice, T. M.; Sigrist, M.

1993-01-01

311

Bond-Alternating Antiferromagnetic S = 1/2 Heisenberg Ladder with Ferromagnetic Diagonal Coupling  

Science.gov (United States)

Using the density matrix renormalization group method, we determine the phase diagram of a frustrated bond-alternating S = 1/2 Heisenberg ladder with ferro-antiferromagnetic couplings at zero temperature. With the interactions between spins along the rungs set, we identify three spin-gapped phases (the Haldane phase, the singlet phase and the dimer phase) in the whole parameter range. The analysis of our data shows that two-leg spin bond-alternating ladders have a rich phase diagram if both rung and diagonal couplings are taken into account.

Li, An-Kang; Lu, Jun-Zhe; Ma, Lei

2009-12-01

312

Bond-Alternating Antiferromagnetic S = 1/2 Heisenberg Ladder with Ferromagnetic Diagonal Coupling  

International Nuclear Information System (INIS)

Using the density matrix renormalization group method, we determine the phase diagram of a frustrated bond-alternating S = 1/2 Heisenberg ladder with ferro-antiferromagnetic couplings at zero temperature. With the interactions between spins along the rungs set, we identify three spin-gapped phases (the Haldane phase, the singlet phase and the dimer phase) in the whole parameter range. The analysis of our data shows that two-leg spin bond-alternating ladders have a rich phase diagram if both rung and diagonal couplings are taken into account

313

Phase diagram of frustrated mixed-spin ladders in the strong-coupling limit  

Science.gov (United States)

We study the ground-state properties of frustrated Heisenberg ferrimagnetic ladders with antiferromagnetic exchange interactions and two types of alternating sublattice spins. In the limit of strong rung couplings, we show that the mixed spin-1/2 and spin-1 ladders can be systematically mapped onto a spin-1/2 Heisenberg model with additional next-nearest-neighbor exchanges. The system is either in a ferrimagnetic state or in a critical spin-liquid state depending on the competition between the spin exchanges along the legs and the diagonal exchanges.

Chen, S.; Wang, L.; Wang, Y. P.

2007-06-01

314

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

315

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.

David Ipsen

2008-04-01

316

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...

317

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

Science.gov (United States)

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

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

2007-08-01

318

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

319

On the Orchard crossing number of prisms, ladders and other related graphs  

CERN Document Server

This paper deals with the Orchard crossing number of some families of graphs which are based on cycles. These include disjoint cycles, cycles which share a vertex and cycles which share an edge. Specifically, we focus on the prism and ladder graphs.

Feder, Elie

2011-01-01

320

Report on a Validity Study of the Tennessee Career Ladder System.  

Science.gov (United States)

To fulfill a mandate of the Tennessee State Legislature, the extent to which the Tennessee Career Ladder System (CLS) is valid for making inferences about the professional competence of teachers was investigated. Evidence of the extent to which the content of the evaluation procedures reflects sound theory, empirical findings, and best practices,…

Baker, Eva; And Others

321

South Dakota Statewide Core Curriculum, Career Ladder and Challenge System: Volumes I and II. Final Report.  

Science.gov (United States)

The two volume final report of the South Dakota Statewide Core Curriculum, Career Ladder, and Challenge System Project, coordinating associated health and nursing education on a statewide basis to achieve a more systematic production and utilization of health manpower, is presented. Volume 1 includes five chapters: (1) and (2) outlining funding…

1975

322

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.

323

Fiscal Viability, Conjunctive and Compensatory Models, and Career-Ladder Decisions: An Empirical Investigation.  

Science.gov (United States)

A study was undertaken to explore cost-effective ways of making career ladder teacher evaluation system decisions based on fewer measures, assessing the relationship of observational variables to other data and final decisions, and comparison of compensatory and conjunctive decision models. Data included multiple scores from eight data sources in…

Mehrens, William A.; And Others

324

Library Media Specialist Orientation Manual, 1985-86. Tennessee Career Ladder Better Schools Program.  

Science.gov (United States)

This document is an orientation manual for the Library Media Specialist Evaluation System, a part of the Tennessee Career Ladder Better Schools Program. This evaluation system was developed by using the best ideas from educational research and from library media specialists in Tennessee. The system was field tested in the fall of 1985. Contained…

Tennessee State Dept. of Education, Nashville.

325

Low-Inference Observation in the Evaluation of Tennessee's Career Ladder Teachers.  

Science.gov (United States)

This paper explores the functioning of the low-inference observation system used as part of the Tennessee Career Ladder evaluation system, which provides teachers with the opportunity to qualify for additional pay on the basis of outstanding performance. The analysis of the functioning of this form is intended to provide the basis for the ongoing…

McLarty, Joyce R.; Rakow, Ernest

326

Properties of lightly doped t-J two-leg ladders  

CERN Document Server

We have numerically investigated the doped t-J ladder using exact diagonalization. We have studied both the limit of strong inter-chain coupling and isotropic coupling. The ladder scales to the Luther-Emery liquid regime in the strong inter-chain coupling limit. In this strong coupling limit there is a simple picture of the excitation spectrum that can be continued to explain the behavior at isotropic coupling. At J=0 we have indications of a ferromagnetic ground state. At a large J/t the ladder is phase separated into holes and a Heisenberg ladder. At intermediate coupling the ground state shows hole pairing with a modified d-wave symmetry. The excitation spectrum separates into a limited number of quasiparticles which carry charge +|e| and spin {1\\over 2} and a triplet magnon mode. At half-filling the former vanish but the latter evolves continuously into the magnon band of the spin liquid. At low doping the quasiparticles form a dilute Fermi gas with a strong attraction but simultaneously the Fermi wave ve...

Troyer, M; Rice, T M; Troyer, Matthias; Tsunetsugu, Hirokazu

1995-01-01

327

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

Energy Technology Data Exchange (ETDEWEB)

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

Berg, E.

2010-05-26

328

Properties of lightly doped t-J two-leg ladders  

Science.gov (United States)

We have numerically investigated the doped t-J ladder using exact diagonalization. We have studied both the limit of strong interchain coupling and isotropic coupling. The ladder scales to the Luther-Emery liquid regime in the strong interchain coupling limit. In this strong coupling limit there is a simple picture of the excitation spectrum that can be continued to explain the behavior at isotropic coupling. At J=0 we have indications of a ferromagnetic ground state. At a large J/t the ladder is phase separated into holes and a Heisenberg ladder. At intermediate coupling the ground state shows hole pairing with a modified d-wave symmetry. The excitation spectrum separates into a limited number of quasiparticles which carry charge +||e|| and spin 1/2 and a triplet magnon mode. At half filling the former vanish but the latter evolves continuously into the magnon band of the spin liquid. At low doping the quasiparticles form a dilute Fermi gas with a strong attraction but simultaneously the Fermi wave vector, as would be measured in photoemission, is large. The dynamical structure factors are calculated and are found to be very similar to calculations on two-dimensional clusters.

Troyer, Matthias; Tsunetsugu, Hirokazu; Rice, T. M.

1996-01-01

329

Critical exponents of S=1/2 Heisenberg ladders with ferromagnetic interchain interaction in magnetic fields  

Science.gov (United States)

The critical properties of the S=1/2 Heisenberg two-leg ladders with a ferromagnetic interchain interaction in magnetic fields are investigated by combining the numerical exact diagonalization method and the finite-size-scaling analysis based on conformal field theory.

Usami, Mamoru; Suga, Sei-ichiro

1999-08-01

330

Diagonal Ladders A New Class of Models for Strongly Coupled Electron Systems  

CERN Document Server

We introduce a class of models defined on ladders with a diagonal structure generated by $n_p$ plaquettes. The case $n_p=1$ corresponds to the necklace ladder and has remarkable properties which are studied using DMRG and recurrent variational ansatzes. The AF Heisenberg model on this ladder is equivalent to the alternating spin-1/spin-1/2 AFH chain which is known to have a ferrimagnetic ground state (GS). For doping 1/3 the GS is a fully doped (1,1) stripe with the holes located mostly along the principal diagonal while the minor diagonals are occupied by spin singlets. This state can be seen as a Mott insulator of localized Cooper pairs on the plaquettes. A physical picture of our results is provided by a $t_p-J_p$ model of plaquettes coupled diagonally with a hopping parameter $t_d$. In the limit $t_d \\to \\infty$ we recover the original $t-J$ model on the necklace ladder while for weak hopping parameter the model is easily solvable. The GS in the strong hopping regime is essentially an "on link" Gutzwiller...

Sierra, G; White, S R; Scalapino, D J; Dukelsky, J

1999-01-01

331

Two-chain spin ladder with frustrating second-neighbor interactions  

Science.gov (United States)

The Heisenberg model on a two-chain spin-12 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.

1998-05-01

332

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

333

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

334

Rats anticipate damaged rungs on the elevated ladder: Applications for rodent models of Parkinson's disease.  

Science.gov (United States)

The present study examined rats' ability to anticipate undetectable wider gaps between rungs produced when they stepped on and dislodged damaged rungs while they traversed a slightly inclined elevated ladder. Rats in the first of three experiments reduced running speeds when they encountered four evenly spaced damaged rungs either always placed on the first or second half of the ladder (the break-a-way (BW) phase) but quickly recovered to their baseline (BL) levels when damaged rungs where replaced with intact rungs (the recovery phase). Rats previously exposed to damaged rungs over the first half of the ladder increased their speeds above BL on its second "safer" half during the recovery phase, a delayed "relief-like" positive contrast effect. In Experiment 2, other rats decreased their speeds more as they approached a single damaged rung at a fixed location when it occurred before than after the mid-point of the ladder. Although they quickly recovered to BL speeds on the portion of the ladder after the damaged rung or replaced intact rung, they never showed any "relief-like"/escape effects. Rats also reduced their likelihood of dislodging the damaged rung with a fore paw over extended BW training. In the third experiment rats encountered a more easily dislodged damaged rung that was signaled by a closer intact rung on half the trials. Under these conditions rats displayed a more reliable positive contrast "relief-like" effect. We discussed how traditional associative and cognitive theories of aversive conditioning account for these findings and their relationship to normal changes in dopamine production and possible effects of reduced production from the substantia nigra pars compacta (SNpc) in the Basal ganglia in rodent models of Parkinson's disease. PMID:25747570

Lopatin, Daniel; Caputo, Nicole; Damphousse, Chelsey; Pandey, Siyaram; Cohen, Jerome

2015-03-01

335

Absence of spin gap in the superconducting ladder compound Sr_2Ca_{12}Cu_{24}O_{41}  

OpenAIRE

Transport and 63^Cu-NMR, Knight shift and T_1, measurements performed on the two-leg spin ladders of Sr_2Ca_{12}Cu_{24}O_{41} single crystals show a collapse of the gap in ladder spin excitations when superconductivity is stabilised under a pressure of 29 kbar. These results support the prediction made with exact diagonalisation techniques in two-leg isotropic t-J ladders of a transition between a low-doping spin gap phase and a gapless 1-D Tomonaga-Luttinger regime.

Mayaffre, H.; Auban-senzier, P.; Je?rome, D.; Poilblanc, D.; Bourbonnais, C.; Ammerahl, U.; Dhalenne, G.; Revcolevschi, A.

1997-01-01

336

Absence of spin gap in the superconducting ladder compound $Sr_{2}Ca_{12}Cu_{24}O_{41}$  

CERN Document Server

Transport and 63^Cu-NMR, Knight shift and T_1, measurements performed on the two-leg spin ladders of Sr_2Ca_{12}Cu_{24}O_{41} single crystals show a collapse of the gap in ladder spin excitations when superconductivity is stabilised under a pressure of 29 kbar. These results support the prediction made with exact diagonalisation techniques in two-leg isotropic t-J ladders of a transition between a low-doping spin gap phase and a gapless 1-D Tomonaga-Luttinger regime.

Mayaffre, H; Jérome, D; Poilblanc, D; Bourbonnais, C; Ammerahl, U; Dhalenne, G; Revcolevschi, A

1997-01-01

337

Thermal conductivity of the hole-doped spin ladder system Sr14-xCaxCu24O41  

Science.gov (United States)

The thermal conductivity of the spin-1/2 ladder system Sr14-xCaxCu24O41 ( x = 0, 2, and 12) has been measured both along ( kappa(c)) and perpendicular to ( kappa(a)) the ladder direction at temperatures between 5 and 300 K. While the temperature dependence of kappa(a) is typical for phonon heat transport, an unusual double-peak structure is observed for kappa(c)(T). We interpret this unexpected feature as a manifestation of quasi-one-dimensional magnon thermal transport mediated by spin excitations along the ladders. PMID:11017307

Sologubenko; Gianno; Ott; Ammerahl; Revcolevschi

2000-03-20

338

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

International Nuclear Information System (INIS)

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

339

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

340

Pairing correlation in the two- and three-leg Hubbard ladders --- Renormalization and quantum Monte Carlo studies  

OpenAIRE

In order to shed light whether the `even-odd conjecture' (even numbers of legs will superconduct accompanied by a spin gap while odd ones do not) for correlated electrons in ladder systems, the pairing correlation is studied for the Hubbard model on a two- and three-leg ladders. We have employed both the weak-coupling renormalization group and the quantum Monte Carlo (QMC) method for strong interactions. For the two-leg Hubbard ladder, a systematic QMC (with a controlled lev...

Kimura, Takashi; Kuroki, Kazuhiko; Aoki, Hideo

1997-01-01

341

A Review of Topography in Fish Culture in Nigria Part Three  

OpenAIRE

A review of topography in fish culture in Nigeria is aimed at enlightening fish culturist more topographical principles. The fish culturist can discuss his plans, projects and understand books on topography, engineering and surveying. Good fish farm construction can only be possible with the right topography. The fish culturists need to understand more principles in topography for good site selection in fish culture. The fish farmer can design and build fishponds, reservoirs and small dams an...

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

2012-01-01

342

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

DEFF Research Database (Denmark)

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

Heppell, Joël; Lorenzen, Niels

1998-01-01

343

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

OpenAIRE

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

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

2007-01-01

344

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

345

Gone Fishing.  

Science.gov (United States)

Presents a hands-on activity in which students create a model of an ocean ecosystem to gain an understanding of how humans can alter biodiversity through their actions. Uses differing levels of fishing technology to explore the concepts of sustainability and overfishing. (Author/SOE)

Olson-Demme, Hillary; Kisiel, Jim

2003-01-01

346

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

347

The value of applying commercial fishers' experience to designed surveys for identifying characteristics of essential fish habitat for adult summer flounder  

OpenAIRE

Identifying the habitat requirements of marine fish is necessary to conserve and manage their populations, but these requirements are poorly understood for many species. One method of screening for important habitat characteristics is to identify differences in habitat features between areas of high and low fish abundance. We tested the association between abundance of adult summer flounder Paralichthys dentatus and benthic habitat features at two study areas in the Middle Atlantic Bight in s...

Slacum, H. W.; Vølstad, Jon Helge; Weber, E. D.; Richkus, W. A.; Diaz, R. J.; Tallent, C. O.

2008-01-01

348

Twisted aromatics, 9-anthryl and 1-pyrenyl terpyridines organize into novel multi-directional 'ladder-like' motifs in the solid state  

Science.gov (United States)

9-Anthryl and 1-pyrenyl terpyridines ( 1 and 2, respectively), key precursors for the design of novel fluorescent sensors have been synthesized and characterized by 1H NMR, mass spectroscopy and X-ray crystallography. Twisted molecular conformations for each 1 and 2 were observed in their single crystal structures. Energy minimization calculations for the 1 and 2 using the semi-empirical AM1 method show that the 'twisted' conformation is intrinsic to these systems. We observe interconnected networks of edge-to-face CH⋯? interactions, which appear to be cooperative in nature, in each of the crystal structures. The two twisted molecules, although having differently shaped polyaromatic hydrocarbon substituents, show similar patterns of edge-to-face CH⋯? interactions. The presently described systems comprise of two aromatic surfaces that are almost orthogonal to each other. This twisted or orthogonal nature of the molecules leads to the formation of interesting multi-directional ladder like supramolecular organizations. A combination of edge-to-face and face-to-face packing modes helps to stabilize these motifs. The ladder like architecture in 1 is helical in nature.

Gulyani, A.; Srinivasa Gopalan, R.; Kulkarni, G. U.; Bhattacharya, S.

2002-10-01

349

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

350

Spin dynamics in the spin-1/2 chain/ladder system (Sr,Ca)14Cu24O41  

International Nuclear Information System (INIS)

Complete text of publication follows. Sr14Cu24O41 is an insulating spin-chain/spin-ladder system which contains a large number of intrinsic holes mainly located in the CuO2 chains. The substitution of Sr for Ca induces an insulator-metal transition at ambient pressure and finally superconductivity occurs under a pressure of about 30 kbar. The spin dynamics has been studied both in the chains and in the ladders subsystems in Sr14-xCaxCu24O41 as functions of both the temperature (between 1.5 K and 300 K) and the calcium doping (x = 0, 6, 12). Quite surprisingly, the magnetic excitation spectra which have been obtained for the ladder subsystem display features which are hardly explainable from the 'simple' spin-ladder theory. A comparison with the results obtained on YBCO in the normal state is given. (author)

351

Comment to: "A note on failure of the ladder approximation to QCD" [Phys. Lett. B 640 (2006) 196  

OpenAIRE

In the paper [Hong-Shi Zong, Wei-Min Sun, Phys. Lett. B 640 (2006) 196], the authors claim that our proof of the inconsistency of the ladder approximation to QCD [Phys. Lett. B 611 (2005) 129] was incorrect. However, their claim is based on a derivation which contains a rough mathematical mistake, namely the unjustified change of variables in the divergent (though regularized) integrals. In this comment I will show this explicitly, so our conclusion that the ladder approxima...

Gogokhia, V.

2008-01-01

352

Assessing upstream fish passage connectivity with network analysis.  

Science.gov (United States)

Hydrologic connectivity is critical to the structure, function, and dynamic process of river ecosystems. Dams, road crossings, and water diversions impact connectivity by altering flow regimes, behavioral cues, local geomorphology, and nutrient cycling. This longitudinal fragmentation of river ecosystems also increases genetic and reproductive isolation of aquatic biota such as migratory fishes. The cumulative effects on fish passage of many structures along a river are often substantial, even when individual barriers have negligible impact. Habitat connectivity can be improved through dam removal or other means of fish passage improvement (e.g., ladders, bypasses, culvert improvement). Environmental managers require techniques for comparing alternative fish passage restoration actions at alternative or multiple locations. Herein, we examined a graph-theoretic algorithm for assessing upstream habitat connectivity to investigate both basic and applied fish passage connectivity problems. First, we used hypothetical watershed configurations to assess general alterations to upstream fish passage connectivity with changes in watershed network topology (e.g., linear vs. highly dendritic) and the quantity, location, and passability of each barrier. Our hypothetical network modeling indicates that locations of dams with limited passage efficiency near the watershed outlet create a strong fragmentation signal but are not individually sufficient to disconnect the system. Furthermore, there exists a threshold in the number of dams beyond which connectivity declines precipitously, regardless of watershed topology and dam configuration. Watersheds with highly branched configurations are shown to be less susceptible to disconnection as measured by this metric. Second, we applied the model to prioritize barrier improvement in the mainstem of the Truckee River, Nevada, USA. The Truckee River application demonstrates the ability of the algorithm to address conditions common in fish passage projects including incomplete data, parameter uncertainty, and rapid application. This study demonstrates the utility of a graph-theoretic approach for assessing fish passage connectivity in dendritic river networks assuming full basin utilization for a given species, guild, or community of concern. PMID:24147411

McKay, S Kyle; Schramski, John R; Conyngham, Jock N; Fischenich, J Craig

2013-09-01

353

Fish Trade  

Science.gov (United States)

This lesson plan presents the global economic, political and social aspects of fisheries, aquaculture and fish collecting, and demonstrates how the practices of all the world's nations affect one another. Students read a number of short articles and use on-line resources to gather information on fisheries and aquaculture, then participate in discussion and essay assignments. Discussion questions, standards alignment, assessment, extensions and additional reference links are provided.

354

Fish screens at hydroelectric diversions  

International Nuclear Information System (INIS)

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

355

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

International Nuclear Information System (INIS)

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

356

Quantum phase near the saturation field in the S =1/2 frustrated spin ladder  

Science.gov (United States)

We present low-temperature specific heat and magnetization measurements of the S = 1/2 organic spin ladder 3-I-V [3-(3-iodophenyl)-1,5-diphenylverdazyl]. A b i n i t i o molecular orbital calculations indicate the existence of an intraladder diagonal interaction Jdiag and three types of interladder interactions. The ferromagnetic Jdiag induces frustration in the spin ladder, which has an essential contribution to the ground state. The obtained phase diagram exhibits a low-field three-dimensional order and a nontrivial phase near the saturation field. The absence of successive phase transition with decreasing temperature and the anomalous behavior of the magnetization curve near the saturation field suggest that these two phases are longitudinal spin-density-wave and spin-multipolar orders, respectively.

Yamaguchi, H.; Miyagai, H.; Kono, Y.; Kittaka, S.; Sakakibara, T.; Iwase, K.; Ono, T.; Shimokawa, T.; Hosokoshi, Y.

2015-03-01

357

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

358

From Spin Ladders to the 2-d O(3) Model at Non-Zero Density  

CERN Document Server

The numerical simulation of various field theories at non-zero chemical potential suffers from severe complex action problems. In particular, QCD at non-zero quark density can presently not be simulated for that reason. A similar complex action problem arises in the 2-d O(3) model -- a toy model for QCD. Here we construct the 2-d O(3) model at non-zero density via dimensional reduction of an antiferromagnetic quantum spin ladder in a magnetic field. The complex action problem of the 2-d O(3) model manifests itself as a sign problem of the ladder system. This sign problem is solved completely with a meron-cluster algorithm.

Chandrasekharan, S; Wiese, U J

2002-01-01

359

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)

360

Explaining choice option attractiveness by beliefs elicited by the laddering method  

DEFF Research Database (Denmark)

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

Grunert, Klaus G.; Bech-Larsen, Tino

2005-01-01

361

Enhancement of chaotic subdiffusion in disordered ladders with synthetic gauge fields  

Science.gov (United States)

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

Yu, Xiaoquan; Flach, Sergej

2014-09-01

362

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

CERN Document Server

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

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

2012-01-01

363

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

CERN Document Server

We show how the low-energy properties of the 2-leg XXZ spin-1/2 ladders with general anisotropy parameter $\\Delta $ on closed geometries can be accounted for in the framework of the m-reduction procedure developed in [1]. In the limit of quasi-decoupled chains, a conformal field theory (CFT) with central charge c=2 is derived and its ability to describe the model with different boundary conditions is shown. Special emphasis is given to the Mobius boundary conditions which generate a topological defect corresponding to non trivial single-spinon excitations. Then, in the case of the 2-leg XXX ladders we discuss in detail the role of various perturbations in determining the renormalization group flow starting from the ultraviolet (UV) critical point with c=2.

Cristofano, Gerardo; Naddeo, Adele; Niccoli, Giuliano

2008-01-01

364

Charge density correlations in t-J ladders investigated by the CORE method  

CERN Document Server

Using 4-site plaquette or rung basis decomposition, the CORE method is applied to 2-leg and 4-leg t-J ladders and cylinders. Resulting range-2 effective hamiltonians are studied numerically on periodic rings taking full advantage of the translation symmetry as well as the drastic reduction of the Hilbert space. We investigate the role of magnetic and fermionic degrees of freedom to obtain the most reliable representation of the underlying model. Spin gaps, pair binding energies and charge correlations are computed and compared to available ED and DMRG data for the full Hamiltonian. Strong evidences for short-range diagonal stripe correlations are found in periodic 4-leg t-J ladders.

Capponi, S; Capponi, Sylvain; Poilblanc, Didier

2002-01-01

365

Calculation of the singlet-triplet gap of the antiferromagnetic Heisenberg model on the ladder  

CERN Document Server

The ground state energy and the singlet-triplet energy gap of the antiferromagnetic Heisenberg model on a ladder is investigated using a mean field theory and the density matrix renormalization group. Spin wave theory shows that the corrections to the local magnetization are infinite. This indicates that no long range order occurs in this system. A flux-phase state is used to calculate the energy gap as a function of the transverse coupling, J_\\perp, in the ladder. It is found that the gap is linear in J_\\perp for J_\\perp\\gg 1 and goes to zero for J_\\perp\\to 0. The mean field theory agrees well with the numerical results.

Azzouz, M; Moukouri, S; Liang Chen

1994-01-01

366

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

367

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

Science.gov (United States)

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 [Phys. Rev. B 57, 11439 (1998)] 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 study the effect of temperature on the phase boundaries and find 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 and are all caused by frustration.

Ramakko, Brandon W.; Azzouz, Mohamed

2007-08-01

368

Spin Hamiltonian for the quantum Hall state in a ladder geometry  

Science.gov (United States)

The first calculation of the true ground state of the parent Hamiltonian proposed by Laughlin [Laughlin, Ann. Phys. 191, 163 (1989)] for the m=2 fractional quantum Hall state on a torus is presented. Laughlin’s model is generalized to the case of a system in a ladder geometry and rewritten in terms of familiar spin-spin interactions, demonstrating that the model corresponds to a long-range Heisenberg Hamiltonian with an additional four-site interaction. The exact diagonalization of the Hamiltonian is performed to extract the energies, correlation functions, sublattice magnetization, and overlap with the quantum Hall state. Our results confirm the recent work showing that the model is not exact [Schroeter, Ann. Phys. 310, 155 (2004)] and also show it to be not without merit: the overlap between the quantum Hall (QH) state and exact ground state approaches the significant value of 0.83 in the limit that the ladder becomes infinitely long.

Kapit, E.; Luitel, P.; Schroeter, D. F.

2006-02-01

369

Spin-Hamiltonian for the Quantum Hall State in a Ladder Geometry  

Science.gov (United States)

The first calculation of the true ground state of the parent-Hamiltonian proposed by Laughlin [R. B. Laughlin, Ann. Phys. 191, 163 (1989)] for the m=2 Fractional Quantum Hall state on a torus is presented. Laughlin's model is generalized to the case of a system in a ladder geometry and rewritten in terms of familiar spin-spin interactions, demonstrating that the model corresponds to a long-range Heisenberg Hamiltonian with an additional four-site interaction. The exact diagonalization of the Hamiltonian is performed to extract the energy, correlation functions, sub-lattice magnetization, and overlap with the Quantum Hall state. Our results confirm the recent work showing that the model is not exact [D. F. Schroeter, Ann. Phys. 310, 155 (2004)] and also show it to be not without merit: the overlap between the QH state and exact ground state approaches the significant value of 0.83 in the limit that the ladder becomes infinitely long.

Kapit, Eliot

2005-03-01

370

Cu NMR/NQR Studies on Magnetism in Impurity/Hole-Doped Spin-Ladder Compounds  

International Nuclear Information System (INIS)

Cu nuclear magnetic resonance (NMR) spectra of impurities (Zn, Ni, and La)-doped spin-1/2 Heisenberg ladder compounds SrCu2O3 (Sr123) are broadened with Curie-like temperature (T) dependence. The spectra have been successfully fit by using a quasi-one-dimensional (Q1D) staggered polarization (SP) model. Such a SP has also revealed in Cu NMR measurements of Sr14-xCaxCu24O41 (Cax) with hole-doped ladders. The origin of possible 3D antiferromagnetic (AF) long-range ordering in (Zn and Ni)-doped Sr123 and Cax around x=12 at low T is considered to be similar. Once unpaired spins S0's are induced and 3D interlayer interaction occurs, the localized spins couple in the whole system

371

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

372

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

International Nuclear Information System (INIS)

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

373

Structure and transport properties of spin ladder cuprate thin films synthesized by molecular beam epitaxy  

International Nuclear Information System (INIS)

Thin films of new compounds belonging to the (Sr,Ca)-Cu-O system have been synthesized using Molecular Beam Epitaxy (MBE). Their typical composition is (Sr,Ca)Cu2O3. The growth conditions have been optimized on two different substrates, MgO (100) and SrTiO3 (100). The structure was determined by high-resolution electron microscopy (HRTEM) and X-ray diffraction measurements on a four-circle diffractometer. Spin ladders Cu2O3 planes are clearly identified on HRTEM micrographs. The c axis stacking of the ladder planes provides various sites for Sr, Ca and O and it could explain the wide range of accessible of doping in these compounds. At high hole-doping levels induced by field effect, superconductive transitions are observed, in the nominally insulating material, the maximum transition temperature Tc being 14 K. (authors)

374

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

375

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

376

Magnetic excitations in two-leg spin 1/2 ladders: experiment and theory  

OpenAIRE

Magnetic excitations in two-leg S=1/2 ladders are studied both experimentally and theoretically. Experimentally, we report on the reflectivity, the transmission and the optical conductivity sigma(omega) of undoped La_x Ca_14-x Cu_24 O_41 for x=4, 5, and 5.2. Using two different theoretical approaches (Jordan-Wigner fermions and perturbation theory), we calculate the dispersion of the elementary triplets, the optical conductivity and the momentum-resolved spectral density of ...

Grueninger, M.; Windt, M.; Nunner, T.; Knetter, C.; Schmidt, K. P.; Uhrig, G. S.; Kopp, T.; Freimuth, A.; Ammerahl, U.; Buechner, B.; Revcolevschi, A.

2001-01-01

377

Entrepreneurial Progress: Climbing The Entrepreneurial Ladder in Europe and The US  

OpenAIRE

We investigate which countries have the highest potential to achieve entrepreneurial progress. This progress is defined using an entrepreneurial ladder with five successive steps: “never thought about starting a business”, “thinking about starting a business”, “taking steps to start a business”, “running a business for less than three years”, and “running a business for more than three years”. We assess the influence of individual-level and country-level variables on progr...

Zwan, P. W.; Verheul, I.; Thurik, A. R.; Grilo, I.

2009-01-01

378

Phase Diagram of the Holstein-Hubbard Two-Leg Ladder  

CERN Document Server

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

Tam, K M; Campbell, D K; Castro-Neto, A H; Tam, Ka-Ming

2006-01-01

379

The driven Jaynes-Cummings ladder: resonances at far-off resonance  

International Nuclear Information System (INIS)

We propose a new scheme of single atom lasers/masers which produces a highly intensity-squeezed light virtually in a temporally stationary Fock-state. We identify the multiphoton resonances in the Jaynes-Cummings Ladder (JCL) system, and extract extremely simple dynamics of the system at the multiphoton resonance at far-off resonant frequencies. We show an anomalously high cavity mode excitation occurs at a particular set of atomic, cavity and the driving field frequencies. (author)

380

Hydroxyl-Substituted Ladder Polyethers via Selective Tandem Epoxidation/Cyclization Sequence.  

Science.gov (United States)

A new and highly selective method for the synthesis of hydroxyl-substituted tetrahydropyrans is described. This method utilizes titanium(IV) isopropoxide and diethyl tartrate to perform a diastereoselective epoxidation followed by in situ epoxide activation and highly selective endo-cyclization to form the desired tetrahydropyran ring. The HIJ ring fragment of the marine ladder polyether yessotoxin was synthesized using this two-stage tactic that proceeds with high efficiency and excellent regioselectivity. PMID:25647091

Czabaniuk, Lara C; Jamison, Timothy F

2015-02-20

381

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

382

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

OpenAIRE

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 at...

Qian, Jing; Zhai, Jingjing; Zhang, Lu; Zhang, Weiping

2015-01-01

383

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

384

Spin-orbital separation in the anisotropic ladder system CaCu2O3  

OpenAIRE

Fractionalization of an electronic quasiparticle into separate spin, charge and orbital parts is a fundamental and very characteristic property of interacting electrons in one dimension. How these phenomena carry over into higher dimensions, however, remains currently unclear and debated. To clarify this point, we studied the spin and orbital excitations of the anisotropic ladder material CaCu2O3, which realizes a first step towards two dimensional correlated electron system...

Bisogni, Valentina; Wohlfeld, Krzysztof; Nishimoto, Satoshi; Monney, Claude; Trinckauf, Jan; Zhou, Kejin; Kraus, Roberto; Koepernik, Klaus; Sekar, Chinnathambi; Strocov, Vladimir; Buechner, Bernd; Schmitt, Thorsten; Brink, Jeroen Den; Geck, Jochen

2013-01-01

385

Finite-size calculations of spin-lattice relaxation rates in Heisenberg spin-ladders  

CERN Document Server

Calculations of nuclear spin-lattice relaxation rates are carried out bymeans of exact diagonalization on small (2 x 6) antiferromagnetic Heisenbergladders, using the simplest forms permitted by symmetry for the hyperfinecouplings for the three nuclear sites in Cu2O3 ladders. Several values of therung/chain exchange ratio have been considered. Comparisons with experimentalresults, field theoretic calculations, and the Gaussian approximation highlightsome open problems.

Gelfand, M P; Gelfand, Martin P.; Mahadevan, Mohan

2000-01-01

386

Phase Diagram of the Spin Ladder with Cyclic Four Spin Exchange  

CERN Document Server

We present the phase diagram of the $S=1/2$ Heisenberg model on the two leg ladder with cyclic four spin exchange, determined by a combination of Exact Diagonalization and Density Matrix Renormalization Group techniques. We find six different phases and regimes: the rung singlet phase, a ferromagnetic phase, two symmetry broken phases with staggered dimers and staggered scalar chiralities, and a gapped region with dominant vector chirality or collinear spin correlations. We localize the phase transitions and investigate their nature.

Laeuchli, A; Troyer, M

2003-01-01

387

Phase Transition and Hidden Orders of the Heisenberg Ladder Model in the Ground State  

Science.gov (United States)

A ground-state phase transition of the antiferromagnetic Heisenberg ladder model is investigated by means of the exact-diagonalization method. A hidden-order correlation is defined for characterizing the ground state. The critical point and the exponent ? are estimated accurately with the use of the hidden-order correlation. The relevance of the resonating-valence-bond theory to the present system is also discussed by inspecting hidden orders and the elementary excitation.

Nishiyama, Yoshihiro; Hatano, Naomichi; Suzuki, Masuo

1995-06-01

388

Equivalence of the antiferromagnetic Heisenberg ladder to a single S=1 chain  

CERN Document Server

I introduce two continuous transformations between the S=1 Heisenberg chain and the antiferromagnetic S=1/2 Heisenberg ladder. Both transformations couple diagonally situated {\\it next nearest neighbor} S=1/2's to form each S=1. Using the density matrix renormalization group, I demonstrate that the two systems are in the same phase. Furthermore, I find that the hidden topological long-range order characterizing the S=1 system is even stronger in the isotropic two-chain system.

White, S R

1995-01-01

389

Equivalence of the antiferromagnetic Heisenberg ladder to a single S=1 chain  

Science.gov (United States)

I introduce two continuous transformations between the S=1 Heisenberg chain and the antiferromagnetic S=1/2 Heisenberg ladder. Both transformations couple diagonally situated next-nearest-neighbor S=1/2's to form each S=1. Using the density matrix renormalization group, I demonstrate that the two systems are in the same phase. Furthermore, I find that the hidden topological long-range order characterizing the S=1 system is even stronger in the isotropic two-chain system.

White, Steven R.

1996-01-01

390

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

Science.gov (United States)

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

Sanchis-Alepuz, Hèlios; Kubrak, Stanislav D.; Fischer, Christian S.

2014-06-01

391

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

International Nuclear Information System (INIS)

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

392

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

CERN Document Server

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

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

2005-01-01

393

Local Displacements, Magnetoelastic Coupling, and Bonding in Spin-Ladder Iron Selenides  

Science.gov (United States)

The spin-ladder ``1-2-3'' compounds BaFe2Se3 and KFe2Se3, built of double-chains of edge-sharing [FeSe4] tetrahedra, are localized-moment antiferromagnetic semiconductors. Total neutron scattering of BaFe2Se3 reveals local iron displacements coupled to long-range ordered antiferromagnetism comprised of ferromagnetic Fe4 plaquettes. The magnitude of the iron displacements follow the antiferromagnetic order parameter: a manifestation of magnetoelastic coupling. These local displacements are essential for properly understanding the electronic structure of these systems, as local structural modulations necessarily perturb the ground state wavefunctions. Furthermore, while iron displacements from magnetoelastic coupling in FeX4-based materials are hypothesized to be important in the emergence of superconductivity, the spin-ladders remain insulating down to 1.8 K, even upon hole doping by substitution of K for Ba. As with the copper oxide superconductors two decades ago, our results highlight the importance of reduced dimensionality spin-ladder compounds in the study of the coupling of spin, charge, and atom positions in superconducting materials.

Neilson, James; Caron, Joseph; Miller, David; Llobet, Anna; McQueen, Tyrel

2012-02-01

394

Zero modes and thermodynamics of disordered spin-1/2 ladders  

International Nuclear Information System (INIS)

The influence of nonmagnetic doping on the thermodynamic properties of two-leg S=1/2 spin ladders is studied in this paper. It is shown that, for a weak interchain coupling, the problem can be mapped onto a model of random mass Dirac (Majorana) fermions. We investigate in detail the structure of the fermionic states localized at an individual mass kink (zero modes) in the framework of a generalized Dirac model. The low-temperature thermodynamic properties are dominated by these zero modes. We use the single-fermion density of states, known to exhibit the Dyson singularity in the zero-energy limit, to construct the thermodynamics of the spin ladder. In particular, we find that the magnetic susceptibility ? diverges at T?0 as 1/Tln2(1/T), and the specific heat behaves as C?1/ln3(1/T). The predictions on magnetic susceptibility are consistent with the most recent results of quantum Monte Carlo simulations on doped ladders with randomly distributed impurities. We also calculate the average staggered magnetic susceptibility induced in the system by such defects. (author)

395

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

396

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.

397

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

398

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

Energy Technology Data Exchange (ETDEWEB)

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

Ratzmann, Paul M.; /Fermilab

1996-07-02

399

Intelligent Fish Freshness Assessment  

OpenAIRE

Fish species identification and automated fish freshness assessment play important roles in fishery industry applications. This paper describes a method based on support vector machines (SVMs) to improve the performance of fish identification systems. The result is used for the assessment of fish freshness using artificial neural network (ANN). Identification of the fish species involves processing of the images of fish. The most efficient features were extracted and combined with the down-sa...

Deena Benjamin; Hongxiu Liu; Guanggui Xu; Dehan Luo; Hamid Gholam Hosseini

2008-01-01

400

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

401

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

402

A Review of Topography in Fish Culture in Nigeria Part 1  

OpenAIRE

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

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

2011-01-01

403

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

DEFF Research Database (Denmark)

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

SØrensen, Elin; Grunert, Klaus G.

1996-01-01

404

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

405

Fishing Fish Stem Cells and Nuclear Transplants  

OpenAIRE

Fish has been the subject of various research fields, ranging from ecology, evolution, physiology and toxicology to aquaculture. In the past decades fish has attracted considerable attention for functional genomics, cancer biology and developmental genetics, in particular nuclear transfer for understanding of cytoplasmic-nuclear relationship. This special issue reports on recent progress made in fish stem cells and nuclear transfer.

Yunhan Hong

2011-01-01

406

Boats to Burn: Bajo Fishing Activity in the Australian Fishing Zone  

OpenAIRE

Under a Memorandum of Understanding between Indonesia and Australia, traditional Indonesian fishermen are permitted access to fish in a designated area inside the 200 nautical mile Australian Fishing Zone (AFZ). However, crew and vessels are regularly apprehended for illegal fishing activity outside the permitted areas and, after prosecution in Australian courts, their boats and equipment are destroyed and the fishermen repatriated to Indonesia. This is an ethnographic study of one group of I...

Stacey, Natasha

2007-01-01

407

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1999-12-01

408

Can Fishing  

Science.gov (United States)

In this outdoor activity, learners go "can fishing" and discover the kinds of aquatic organisms that live in and on submerged cans. Discarded bottles and cans surprisingly provide protection for young aquatic organisms, because the young are small enough to fit inside while larger predators stay out. Learners consider how human activities improve or harm the quality of animal and plant habitats. This activity can be combined with a cleanup day and/or with the Litter Critters activity from the same source. The animal observation part of this activity can be expanded to younger ages, if can retrieval from the natural water bodies is handled by an older learner or adult. (Preparation time will vary depending on how many can grabbers are needed).

Lawrence Hall of Science

1981-01-01

409

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.

410

Traditional fishing tools  

OpenAIRE

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

2009-01-01

411

Magnetization plateau in the S=1/2 spin ladder with alternating rung exchange  

CERN Document Server

We have studied the ground state phase diagram of a spin ladder with alternating rung exchange $J^{n}_{\\perp} = J_{\\perp}[1 + (-1)^{n} \\delta ]$ in a magnetic filed, in the limit where the rung coupling is dominant. In this limit the model is mapped onto an $XXZ$ Heisenberg chain in a uniform and staggered longitudinal magnetic fields, where the amplitude of the staggered field is $\\sim \\delta$. We have shown that the magnetization curve of the system exhibits a plateau at magnetization equal to the half of the saturation value. The width of a plateau scales as $\\delta^{\

Poghosyan, G

2006-01-01

412

Spin dynamics of SrCu2O3 and the Heisenberg ladder  

International Nuclear Information System (INIS)

The S=1/2 Heisenberg antiferromagnet in the ladder geometry is studied as a model for the spin degrees of freedom of SrCu2O3. The susceptibility and the spin-echo decay rate are calculated using a quantum Monte Carlo technique, and the spin-lattice relaxation rate is obtained by maximum-entropy analytic continuation of imaginary-time correlation functions. All calculated quantities are in reasonable agreement with experimental results for SrCu2O3 if the exchange coupling J?850 K. However, for the susceptibility fit an anomalously low factor is required. copyright 1996 The American Physical Society

413

Pair Correlations of a Spin-Imbalanced Fermi Gas on Two-Leg Ladders  

International Nuclear Information System (INIS)

We study the pair correlations of a spin-imbalanced two-leg ladder with attractive interactions, using the density matrix renormalization group method. We identify regions in the phase diagram spanned by the chemical potential and the magnetic field that can harbor Fulde-Ferrell-Larkin-Ovchinnikov- (FFLO-)like physics. Results for the pair structure factor, exhibiting multiple pairing wave vectors, substantiate the presence of FFLO-like correlations. We further discuss phase separation scenarios induced by a harmonic trap, which differ from the case of isolated chains

414

NMR study on the quantum spin ladder NH4CuCl3  

International Nuclear Information System (INIS)

Cu-NMR study in the field up to 30 T has been performed on the two-legged quantum spin ladder system NH4CuCl3 which shows the two-stepped plateaus in magnetization. By analyzing the angular dependence of the peak shift, observed Cu-NMR spectra are assigned to the singlet site with a very small magnetic shift. The temperature dependence of this shift does not reflect that of the macroscopic magnetization, indicating that the excited triplet sites in NH4CuCl3 have a tendency to be immobile at low temperatures

415

The two loop crossed ladder vertex diagram with two massive exchanges  

International Nuclear Information System (INIS)

We compute the (three) master integrals for the crossed ladder diagram with two exchanged quanta of equal mass. The differential equations obeyed by the master integrals are used to generate power series expansions centered around all the singular (plus some regular) points, which are then matched numerically with high accuracy. The expansions allow a fast and precise numerical calculation of the three master integrals (better than 15 digits with less than 30 terms in the whole real axis). A conspicuous relation with the equal-mass sunrise in two dimensions is found. Comparison with a previous large momentum expansion is made finding complete agreement

416

Transfer-matrix renormalization group study of spin ladders with cyclic four-spin interactions  

Science.gov (United States)

The temperature dependence of the specific heat and spin susceptibility of spin ladders with cyclic four-spin interactions in the rung-singlet phase is explored by making use of the transfer-matrix renormalization group method. The values of the spin gap are extracted from the specific heat and susceptibility, respectively. It is found that for different relative strengths between interchain and intrachain interactions, the spin gap is approximately linear with the cyclic four-spin interaction in the region far away from the critical point. Furthermore, we show that the dispersion for the one-triplet magnon branch can be obtained by numerically fitting the partition function.

Lu, H. T.; Sun, L. Q.; Qin, Shaojin; Wang, Y. J.

2006-12-01

417

Jordan-Wigner approach to dynamic correlations in spin-ladders  

OpenAIRE

We present a method for studying the excitations of low-dimensional quantum spin systems based on the Jordan-Wigner transformation. Using an extended RPA-scheme we calculate the correlation function of neighboring spin flips which well approximates the optical conductivity of ${\\rm Sr_2CuO_3}$. We extend this approach to the two-leg $S=1/2$--ladder by numbering the spin operators in a meander-like sequence. We obtain good agreement with the optical conductivity of the spin l...

Nunner, Tamara S.; Kopp, Thilo

2002-01-01

418

Eigenfunctions and matrix elements for a class of eigenvalue problems with staggered ladder spectra  

International Nuclear Information System (INIS)

We present an alternate solution to an eigenvalue problem which arises in the study of the Fokker-Planck equation for generalized Ornstein-Uhlenbeck processes. We obtain the staggered ladder spectra found previously but in addition we obtain the normalized eigenfunctions in terms of associated Laguerre polynomials. The representation of the eigenfunctions in this form greatly simplifies the evaluation of matrix elements required in calculating ensemble averages and correlation coefficients for various observables. The solution to the eigenvalue problem is given in the generic and general cases

419

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

International Nuclear Information System (INIS)

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

420

Anomalous Scaling of the SO(8) Symmetric Phases in the Two-Leg Ladder  

CERN Document Server

We carry out a complete analytical stability study for the SO(8) symmetric phases in the weakly-interacting two-leg ladder. It is shown that the SO(8) symmetry is robust under generic perturbations. Since there are no fixed points in the one-loop renormalization group equations, the conventional classification of relevant and irrelevant perturbations fails in this case. A new classification is defined and explained in detail. It leads to the anomalous scaling in the ratios of excitation gaps and an universal exponent 1/3 is extracted. This new method is also applied to the well studied 2D Ising model and similar exponent is calculated.

Lin, H H

2000-01-01

421

Differences Between Hole and Electron Doping of a Two-Leg CuO Ladder  

OpenAIRE

Here we report results of a density-matrix-renormalization-group (DMRG) calculation of the charge, spin, and pairing properties of a two-leg CuO Hubbard ladder. The outer oxygen atoms as well as the rung and leg oxygen atoms are included along with near-neighbor and oxygen-hopping matrix elements. This system allows us to study the effects of hole and electron doping on a system which is a charge transfer insulator at a filling of one hole per Cu and exhibits power law, d-wa...

Nishimoto, S.; Jeckelmann, E.; Scalapino, D. J.

2002-01-01

422

Magnetic field effects on the incommensurate order in coupled spin ladders systems  

Science.gov (United States)

Motivated by recent neutron scattering results on CaCu_2O3 (Kiryukhin et al., cond-mat/0009158) we studied models of coupled antiferromagnetic Heisenberg plaquettes and ladders under magnetic fields by exact diagonalization and quantum Monte Carlo. We have also included a Dzialoshinskii-Moriya (DM) interaction and we have also analyzed this model in the presence of both magnetic and nonmagnetic impurities. We found that the incommensurate (IC) magnetic structure which we have previously obtained with both ferromagnetic and frustrated interladder couplings disappear as expected with magnetic field. The overall behavior of the IC peaks remains relatively unaffected by both DM interactions and impurities.

Riera, Jose; Dalosto, Sergio

2001-03-01

423

Phase diagram of a spin ladder with cyclic four-spin exchange  

Science.gov (United States)

We present the phase diagram of the S=1/2 Heisenberg model on the two leg ladder with cyclic four-spin exchange, determined by a combination of exact diagonalization and density-matrix renormalization group techniques. We find six different phases and regimes: the rung singlet phase, a ferromagnetic phase, two symmetry broken phases with staggered dimers and staggered scalar chiralities, and a gapped region with dominant vector chirality, or collinear spin correlations. We localize the phase transitions and investigate their nature.

Läuchli, A.; Schmid, G.; Troyer, M.

2003-03-01

424

Excitation spectrum and ground-state properties of the S=12 Heisenberg ladder with staggered dimerization  

Science.gov (United States)

We study the excitation spectrum and ground-state properties of the two-leg S=12 quantum spin ladder with staggered dimerization. Two massive phases separated by a critical line are found, as predicted by previous analysis, based on the nonlinear sigma model. We have used dimer series expansions, exact diagonalization of small clusters, and diagrammatic analysis of an effective interacting Bose gas Hamiltonian, obtained by using the bond operator representation for spins. We compute the excitation spectrum in the phase, dominated by strong rungs in the parameter regimes far away and close to the point of instability. The exact location of the phase boundary is determined.

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

1999-05-01

425

Quantum and classical criticalities in the frustrated two-leg Heisenberg ladder  

International Nuclear Information System (INIS)

This paper is about the frustration-induced criticality in the antiferromagnetic Heisenberg model on the two-leg ladder with exchange interactions along the chains, rungs, and diagonals, and also about the effect of thermal fluctuations on this criticality. The method used is the bond-mean-field theory, which is based on the Jordan-Wigner transformation in dimensions higher than one. In this paper, we will summarize the main results presented in a talk, and report on new results about the couplings and temperature dependences of the spin susceptibility. (author)

426

Numerical diagonalization study of an S=1/2 ladder model with open boundary conditions  

Science.gov (United States)

Low-lying energy states of an S=1/2 ladder model are investigated by applying the numerical diagonalization method to finite clusters. This model has the antiferromagnetic intrachain coupling J (J>0) and the ferromagnetic interchain one -?J (?>0). Both the inverse correlation length ?-1(?) and an energy gap are shown to be finite at least for ?>=0.05, the former of which is shown to approach the same value as that of the S=1 antiferromagnetic Heisenberg chain with increasing ?. A generation mechanism of the gap is also discussed in terms of a simple model by using the Lieb-Mattis theorem.

Watanabe, Hiroshi

1994-11-01

427

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+

428

Ground-state phase diagram of a spin-1/2 frustrated three-leg antiferromagnetic Heisenberg ladder  

Science.gov (United States)

Using the density matrix renormalization group method we have studied the ground-state phase diagram of a spin-1/2 frustrated three-leg antiferromagnetic Heisenberg ladder, and identified two phases corresponding to the spin-3/2 chain and the standard spin ladder. Varying the diagonal coupling J× leads to a quantum phase transition from one ground state to the other, but does not alter the gapless nature of the excitation spectra. On the phase boundary, the degenerate ground states form a chiral spin liquid with a central charge c=2. The critical value of J× is insensitive to the number of legs in the ladder, suggesting that a quantum phase transition may occur at J×=0.6 for the isotropic spin-1/2 antiferromagnetic Heisenberg model on the square lattice.

Wang, Xiaoqun; Zhu, Ningsheng; Chen, Changfeng

2002-11-01

429

The Peer Review Model for Managing a Career Ladder/Master Teacher/Performance Pay Program for Elementary and Secondary Schools.  

Science.gov (United States)

To compete with other professions for the most able people, teaching needs a career ladder system for elementary and secondary teachers comparable to the peer review model offered in higher education. Such a system should consist of three levels. Following the initial, probationary position on the career ladder, that of beginning instructor, the…

Bell, T. H.

430

Clostridium botulinum in fish.  

Science.gov (United States)

1407 fish caught in Scandinavian waters, the North Sea and the North Atlantic have been examined for the presence of Cl. botulinum. The incidence in gut samples expressed as percentage of fish tested was generally highest in fish from Scandinavian coastal waters and the Baltic Sea (4--43%), decreasing in fish from the North Sea (0--8%), and the organism was practically absent in fish from the North Atlantic. When gut samples were examined, the incidence was highest in demersal fish (cod and flatfish) as compared with pelagic fish (herring). The latter fish species were mainly contaminated on outer surfaces and gills. Only type E was detected in this survey, and Cl. botulinum was not detected in any wild fresh water fish. It is suggested that type E spores may originate in the sea bed and that they be spread by fish and water currents. PMID:382097

Huss, H H; Pedersen, A

1979-05-01

431

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

432

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

433

0- and 2/3-magnetization plateaus in three-leg antiferromagnetic Heisenberg spin-1/2 ladders with leg-dimerization  

International Nuclear Information System (INIS)

Magnetic properties of three-leg antiferromagnetic Heisenberg spin-1/2 ladders with different dimerization patterns have been studied using the bond mean-field theory. Our results show that rung-columnar ladders are thermodynamically stable states for large rung-to-leg coupling ratios. Magnetization curves of leg-columnar and leg-staggered ladders always exhibit 0- and 2/3-magnetization plateaus, which do not appear in rung-columnar and rung-staggered ladders. In leg-dimerized ladders, the formation of spin dimers in the three legs results in the appearance of the 0- and 2/3-magnetization plateaus. Spin configuration in the 2/3-magnetization plateau can be understood from the mean-field bond parameters.

434

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

DEFF Research Database (Denmark)

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

Thielemann, B.; Rüegg, C.

2009-01-01

435

Low-energy properties of antiferromagnetic spin-1/2 Heisenberg ladders with an odd number of legs  

CERN Document Server

An effective low-energy description for multi-leg spin-1/2 Heisenberg ladders with an odd number of legs is proposed. Using a newly developed Monte Carlo loop algorithm and exact diagonalization techniques, the uniform and staggered magnetic susceptibility and the entropy are calculated for ladders with 1, 3, and 5 legs. These systems show a low-temperature scaling behavior similar to spin-1/2 chains with longer ranged unfrustrated exchange interactions. The spinon velocity does not change as the number of legs increases, but the energy scale parameter decreases markedly.

Frischmuth, B; Sierra, G; Rice, T M; Frischmuth, Beat; Haas, Stephan; Sierra, German

1997-01-01

436

Spinon excitation and M\\"obius boundary condition in S=1/2 antiferromagnetic Heisenberg spin ladder with zigzag structure  

CERN Document Server

We investigate the low-lying excitation of the antiferromagnetic zigzag spin ladder with M\\"obius boundary condition. Using the Lanczos and Householder diagonalization methods, we calculate the excitation spectrum of the zigzag ladder in the momentum space. We then show that the topological defect generated by the M\\"obius boundary provides the clear evidence of the single spinon excitation. On the basis of the obtained single-spinon dispersion curve, we analyze the two-spinon scattering states under the usual periodic boundary condition. We further discuss the interaction effect between the spinons, and the connection to the cusp singularity in the magnetization process.

Okunishi, K; Okunishi, Kouichi; Maeshima, Nobuya

2001-01-01

437

Low-energy properties of antiferromagnetic spin-1/2 Heisenberg ladders with an odd number of legs  

Science.gov (United States)

An effective low-energy description for multileg spin- Heisenberg ladders with an odd number of legs is proposed. Using a recently developed Monte Carlo loop algorithm and exact-diagonalization techniques, the uniform and staggered magnetic susceptibility and the entropy are calculated for ladders with one, three, and five legs. These systems show a low-temperature scaling behavior similar to spin- chains with longer ranged unfrustrated exchange interactions. The spinon velocity does not change as the number of legs increases, but the energy scale parameter decreases markedly.

Frischmuth, Beat; Haas, Stephan; Sierra, German; Rice, T. M.

1997-02-01

438

Spinon excitation and Möbius boundary condition in S=1/2 antiferromagnetic Heisenberg spin ladder with zigzag structure  

Science.gov (United States)

We investigate the low-lying excitation of the antiferromagnetic zigzag spin ladder with Möbius boundary condition. Using the Lanczos and Householder diagonalization methods, we calculate the excitation spectrum of the zigzag ladder in the momentum space. We then show that the topological defect generated by the Möbius boundary provides the clear evidence of the single-spinon excitation. On the basis of the obtained single-spinon dispersion curve, we analyze the two-spinon scattering states under the usual periodic boundary condition. We further discuss the interaction effect between the spinons, and the connection to the cusp singularity in the magnetization process.

Okunishi, Kouichi; Maeshima, Nobuya

2001-12-01

439

Signal Cloaking by Electric Fish  

Science.gov (United States)

Electric fish produce weak electric fields to image their world in darkness and to communicate with potential mates and rivals. Eavesdropping by electroreceptive predators exerts selective pressure on electric fish to shift their signals into less-detectable high-frequency spectral ranges. Hypopomid electric fish evolved a signal-cloaking strategy that reduces their detectability by predators in the lab (and thus presumably their risk of predation in the field). These fish produce broad-frequency electric fields close to the body, but the heterogeneous local fields merge over space to cancel the low-frequency spectrum at a distance. Mature males dynamically regulate this cloaking mechanism to enhance or suppress low-frequency energy. The mechanism underlying electric-field cloaking involves electrogenic cells that produce two independent action potentials. In a unique twist, these cells orient sodium and potassium currents in the same direction, potentially boosting their capabilities for current generation. Exploration of such evolutionary inventions could aid the design of biogenerators to power implantable medical devices, an ambition that would benefit from the complete genome sequence of a gymnotiform fish.

Philip K. Stoddard and Michael R. Markham (Florida International University, Miami; )

2008-05-01

440

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

Directory of Open Access Journals (Sweden)

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

Briand C.

2012-01-01

441

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

442

Elimination of Oil Residual inside the Copper Pipe Using Ladder Technique  

Directory of Open Access Journals (Sweden)

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

Witsarut Sriratana

2013-01-01

443

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

444

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

International Nuclear Information System (INIS)

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

445

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

Science.gov (United States)

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

Cristofano, Gerardo; Marotta, Vincenzo; Naddeo, Adele; Niccoli, Giuliano

2008-12-01

446

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

447

Frustration-induced plateaus in S?(1)/(2) Heisenberg spin ladders  

Science.gov (United States)

We study the T=0 magnetization of frustrated two-leg spin ladders with arbitrary value of the spin S . In the strong-rung limit, we use degenerate perturbation theory to prove that frustration leads to magnetization plateaus at fractional values of the magnetization for all spins S and to determine the critical ratios of parallel to diagonal inter-rung couplings for the appearance of these plateaus. These ratios depend both on the plateau and on the spin. To confirm these results and to investigate the properties of these ladders away from the strong-coupling limit, we have performed extensive density-matrix renormalization-group calculations for S?2 . For large enough inter-rung couplings, all plateaus simply disappear, leading to a magnetization curve typical of integer-spin chains in a magnetic field. The intermediate region turns out to be surprisingly rich however, with, upon increasing the inter-rung couplings, the development of magnetization jumps and, in some cases, the appearance of one or more phase transitions inside a given plateau.

Michaud, Frédéric; Coletta, Tommaso; Manmana, Salvatore R.; Picon, Jean-David; Mila, Frédéric

2010-01-01

448

X-ray laser without inversion in a three-level ladder system  

International Nuclear Information System (INIS)

A scheme for obtaining laser in the deep x-ray regime is proposed based on the principle of gain without inversion. A ladder scheme is proposed in Ar+8 system. In this system, conventional lasing with population inversion has been obtained in a neonlike fashion. This lasing field is proposed for the drive field on the higher transition of the ladder. A coherent field obtained in the high harmonics ultrashort laser provides the probe field to be amplified. This will be selected to best match the frequency needed for the transition from lower level of the present x-ray lasing to the ground state. Numerical calculations in the bare state picture exhibit possible gain at resonance, and at the Rabi side bands, for appropriate choice of system parameters, i.e., the strength of the driving field, the strength of the incoherent pump that provides the required energy needed for the inversionless amplification and the deexcitation rate. The latter rate is detrimental to lasing as it increases. It is quite interesting to note that the system exhibits surprisingly high stability for gain without inversion even for quite high rate of the incoherent deexcitation processes. Real and imaginary parts of the coherences were also obtained for detuned drive and probe fields. These provide insight into the role played by the quantum interference. The present theoretical calculations give high confidence in the quantum interference process as a candidate for realizing very shortss as a candidate for realizing very short wavelength laser

449

Quantum Magnetism of Spin-Ladder Compounds with Trapped-Ion Crystals  

CERN Document Server

The quest for experimental platforms that allow for the exploration, and even control, of the interplay of low dimensionality and frustration is a fundamental challenge in several fields of quantum many-body physics, such as quantum magnetism. Here, we propose the use of cold crystals of trapped ions to study a variety of frustrated quantum spin ladders. By optimizing the trap geometry, we show how to tailor the low dimensionality of the models by changing the number of legs of the ladders. Combined with a method for selectively hiding of ions provided by laser addressing, it becomes possible to synthesize stripes of both triangular and Kagome lattices. Besides, the degree of frustration of the phonon-mediated spin interactions can be controlled by shaping the trap frequencies. We support our theoretical considerations by initial experiments with planar ion crystals, where a high and tunable anisotropy of the radial trap frequencies is demonstrated. We take into account an extensive list of possible error sou...

Bermudez, A; Ott, K; Kaufmann, H; Ulm, S; Schmidt-Kaler, F; Retzker, A; Plenio, M B

2012-01-01

450

Quantum magnetism of spin-ladder compounds with trapped-ion crystals  

International Nuclear Information System (INIS)

The quest for experimental platforms that allow for the exploration, and even control, of the interplay of low dimensionality and frustration is a fundamental challenge in several fields of quantum many-body physics, such as quantum magnetism. Here, we propose the use of cold crystals of trapped ions to study a variety of frustrated quantum spin ladders. By optimizing the trap geometry, we show how to tailor the low dimensionality of the models by changing the number of legs of the ladders. Combined with a method for selectively hiding ions provided by laser addressing, it becomes possible to synthesize stripes of both triangular and Kagome lattices. Besides, the degree of frustration of the phonon-mediated spin interactions can be controlled by shaping the trap frequencies. We support our theoretical considerations by initial experiments with planar ion crystals, where a high and tunable anisotropy of the radial trap frequencies is demonstrated. We take into account an extensive list of possible error sources under typical experimental conditions, and describe explicit regimes that guarantee the validity of our scheme. (paper)

451

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.

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

2014-05-01

452

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

453

Fish barriers  

International Nuclear Information System (INIS)

In addition to literature reviews laboratory experiments with both strobe light and different kinds of sound stimuli were carried out. In the experiments silver eel, brown trout, arctic char and salmon smolts were tested. The experiments showed that in darkness silver eel avoided strobe light with intensities between 0.4 and 8.7 lux with 80-90% avoidance in 8.7 lux. The avoidance reactions decreased when background light was raised to 9 lux. Brown trout did not show as strong avoidance reactions possibly due to aggressive behaviour between different individuals of brown trout. The avoidance reaction was however more pronounced in dim background lift with an intensity of 5 lux than in darkness. The experiments also showed that the avoidance reactions started within a few seconds after exposure to strobe light. The frequencies 6.0 and 15 Hz were more effective as triggers of avoidance reactions than were the frequencies 2.1 and 160 Hz. Arctic char did not show any avoidance reactions to strobe light. It was actually attracted to strobe light with the frequency 160 Hz in total darkness and indifferent in dim background light 10 lux. Experiments in running water also showed that salmon smolts could be diverted from an area exposed to strobe light with the frequency 15.0 Hz. The effect was more pronounced in darkness than in dim background light and also more pronounced when water current was 20 cm/s than when it was 40 or 60 cm/s. Experiments to test the avoidance reactions to sound was also performed. The evaluation of these results where however complicated by the fact that the fishes swam rapidly to and fro in the experimental chamber and thus by pure chance very frequently were close to the sound generator

454

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

455

Anglers' fishing problem  

OpenAIRE

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...

Karpowicz, Anna; Szajowski, Krzysztof

2011-01-01

456

The Bethe-Salpeter equation for the imaginary part of the scattering amplitude in the ladder approximation  

International Nuclear Information System (INIS)

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. (author)

457

Spin-1/2 Heisenberg ladder: variation of entanglement and fidelity measures close to quantum critical points  

CERN Document Server

We consider a two-chain, spin-1/2 antiferromagnetic Heisenberg spin ladder in an external magnetic field H. The spin ladder is known to undergo second order quantum phase transitions (QPTs) at two critical values, Hc1 and Hc2, of the magnetic field. There are now known examples of strongly coupled (rung exchange interaction much stronger than nearest-neighbour intrachain exchange interaction) organic ladder compounds in which QPTs have been experimentally observed. In this paper, we investigate whether well-known bipartite entanglement meaures like one-site von Neumann entropy, two-site von Neumann entropy and concurrence develop special features close to the quantum critical points. As suggested by an earlier theorem, the first derivatives of the measures with respect to magnetic field are expected to diverge as H tends to Hc1 and Hc2. Based on numerical diagonalization data and a mapping of the strongly-coupled ladder Hamiltonian onto the XXZ chain Hamiltonian, for which several analytical results are known...

Tribedi, Amit

2008-01-01

458

Topological order and magnetic flux fractionalization in Josephson junction ladders with Mobius boundary conditions: a twisted CFT description  

CERN Document Server

We propose a CFT description for a closed one-dimensional fully frustrated ladder of quantum Josephson junctions with Mobius boundary conditions (see cond-mat/0503555; we show how such a system can develop topological order thanks to flux fractionalization. Such a property is crucial for its implementation as a "protected" solid state qubit.

Cristofano, G; Naddeo, A; Niccoli, G; Cristofano, Gerardo; Marotta, Vincenzo; Naddeo, Adele; Niccoli, Giuliano

2005-01-01

459

Heat transport imaging in the spin-ladder compound Ca9La5Cu24O41  

International Nuclear Information System (INIS)

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

460

Heat transport imaging in the spin-ladder compound Ca 9La 5Cu 24O 41  

Science.gov (United States)

All-optical heat transport imaging on the spin-ladder compound Ca 9La 5Cu 24O 41 is presented. A 'time-of-flight' principle is discussed along with its experimental verification which can be used to measure the bulk thermal diffusion constant. The results of the thermal imaging experiments clearly demonstrate anisotropic magnon heat transport.

Otter, M.; Krasnikov, V. V.; Fishman, D. A.; Pshenichnikov, M. S.; Saint-Martin, R.; Revcolevschi, A.; van Loosdrecht, P. H. M.

2009-04-01