WorldWideScience

Sample records for fish ladder design

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

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Patrick D.; Orsborn, John F.

    1985-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Carlos Sérgio Agostinho

    2007-01-01

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

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

    Scientific Electronic Library Online (English)

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

    2012-10-01

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

  4. Passage and behaviour of cultured Lake Sturgeon in a prototype side-baffle fish ladder: I. Ladder hydraulics and fish ascent

    Science.gov (United States)

    Kynard, B.; Pugh, D.; Parker, T.

    2011-01-01

    Research and development of a fish ladder for sturgeons requires understanding ladder hydraulics and sturgeon behaviour in the ladder to insure the ladder is safe and provides effective passage. After years of research and development, we designed and constructed a full-scale prototype side-baffle ladder inside a spiral flume (38.3m long??1m wide??1m high) on a 6% (1:16.5) slope with a 1.92-m rise in elevation (bottom to top) to test use by sturgeons. Twenty-eight triangular side baffles, each extending part way across the flume, alternated from inside wall to outside wall down the ladder creating two major flow habitats: a continuous, sinusoidal flow down the ladder through the vertical openings of side-baffles and an eddy below each side baffle. Ascent and behaviour was observed on 22 cultured Lake Sturgeon=LS (Acipenser fulvescens) repeatedly tested in groups as juveniles (as small as 105.1cm TL, mean) or as adults (mean TL, 118cm) during four periods (fall 2002 and 2003; spring 2003 and 2007). Percent of juveniles entering the ladder that ascended to the top was greater in spring (72.7%) than in fall (40.9-45.5%) and 90.9% of 11 adults, which ascended as juveniles, ascended to the top. Six LS (27.3%) never swam to the top and seven (31.8%) swam to the top in all tests, indicating great variability among individuals for ascent drive. Some LS swam directly to the top in <1min, but most rested in an eddy during ascent. Juveniles swimming through outside wall baffle slots (mean velocity, 1.2ms-1) swam at 1.8-2.2body lengthss-1 and 3.2-3.3tail beatss-1, either at or approaching prolonged swimming speed. The side-baffle ladder was stream-like and provided key factors for a sturgeon ladder: a continuous flow and no full cross-channel walls, abundant eddies for resting, an acceptable water depth, and a water velocity fish could ascend swimming 2bls-1. A side-baffle ladder passes LS and other moderate-swimming fishes. ?? 2011 Blackwell Verlag, Berlin.

  5. 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)

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

    Energy Technology Data Exchange (ETDEWEB)

    Powers, Patrick D.; Orsborn, John F.

    1985-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Domingo Rodriguez Fernandez

    2004-08-01

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

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

    Directory of Open Access Journals (Sweden)

    Sérgio Makrakis

    2007-01-01

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

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

    Scientific Electronic Library Online (English)

    Fernando Mayer, Pelicice; Carlos Sérgio, Agostinho.

    2012-10-01

    Full Text Available 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.

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

    OpenAIRE

    Domingo Rodriguez Fernandez; Angelo Antônio Agostinho; Luis Mauricio Bini

    2004-01-01

    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 down...

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

    OpenAIRE

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

    2007-01-01

    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 wer...

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

    Scientific Electronic Library Online (English)

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

    2012-10-01

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

  13. Design of Dual Bandpass and Bandreject LC Ladder Filters

    Directory of Open Access Journals (Sweden)

    J. Hospodka

    2006-09-01

    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.

  14. 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.

  15. Design a Fish

    Science.gov (United States)

    Twin Cities Public Television, Inc.

    2007-01-01

    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.

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

    Scientific Electronic Library Online (English)

    Carlos Bernardo Mascarenhas, Alves.

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

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

    Scientific Electronic Library Online (English)

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

    2006-06-01

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

  18. Fish friendly designs

    International Nuclear Information System (INIS)

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

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

    OpenAIRE

    Baigu?n, Claudio R. M.; Nestler, John M.; Priscilla Minotti; Norberto Oldani

    2012-01-01

    The Route 28 Dam has the potential to block fish movements from La Estrella marsh to the Pilcomayo River. In addition, the many fish that concentrate immediately downstream of the dam may suffer high mortality when they are stranded during low water periods. The goals of this study are to determine if fish are able to pass the spillway and to assess if the design of the installed ladders (pool and weir type) effectively supports upstream migration of Prochilodus lineatus (sábalo). Results sh...

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

    Directory of Open Access Journals (Sweden)

    Domingo Rodrigues Fernandez

    2007-01-01

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

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

    Scientific Electronic Library Online (English)

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

    Full Text Available 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 smaller fish in the samples. The total abundance of smal

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

    Directory of Open Access Journals (Sweden)

    Chun-He SONG

    2009-07-01

    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.

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

    Scientific Electronic Library Online (English)

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

    2014-01-01

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

  4. Voegelin's Ladder

    Directory of Open Access Journals (Sweden)

    Nathan Harter

    2006-06-01

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

  5. 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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-02-01

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

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

    Scientific Electronic Library Online (English)

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

    2012-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Claudio R. M. Baigún

    2012-10-01

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

  9. Materials design principles of ancient fish armour

    Science.gov (United States)

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

    2008-09-01

    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.

  10. Detecting Cerebellar Phenotypes with the Erasmus Ladder

    OpenAIRE

    Cupido, A.

    2009-01-01

    I designed, created and established a new motor behavioural task for mice, the Erasmus Ladder. It is now a quick and reliable behavioural task to determine if (mutant) mice could be a good model for a neurological disease.

  11. The Design and Implementation of a Biomimetic Robot Fish

    Directory of Open Access Journals (Sweden)

    Chao Zhou

    2008-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

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

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

    Science.gov (United States)

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

    2015-06-01

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

  14. Fish swarm optimization algorithm applied to engineering system design

    Scientific Electronic Library Online (English)

    Fran Sérgio, Lobato; Valder, Steffen Jr..

    2014-01-01

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

  15. Bioinspiration from fish for smart material design and function

    Science.gov (United States)

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

    2011-09-01

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

  16. 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

  17. Hole doped Hubbard ladders

    CERN Document Server

    Fehske, H; Wellein, G; Jeckelmann, E

    2006-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Marshall C. Richmond

    2007-11-01

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

  19. 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

  20. Design and construction of Eicher penstock fish screens

    International Nuclear Information System (INIS)

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

  1. 29 CFR 1926.1053 - Ladders.

    Science.gov (United States)

    2010-07-01

    ...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...

  2. Particle-Hole Ladders

    OpenAIRE

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

    2002-01-01

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

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

    International Nuclear Information System (INIS)

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

  4. Design and construction of an Electric Fish Finder

    Scientific Electronic Library Online (English)

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

    2007-09-01

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

  5. Design and construction of an Electric Fish Finder

    Directory of Open Access Journals (Sweden)

    William G. R. Crampton

    2007-09-01

    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.

  6. Trion ladder diagrams

    OpenAIRE

    Combescot, M.; Betbeder-Matibet, O.

    2002-01-01

    We first derive a new ``commutation technique'' for an exciton interacting with electrons, inspired from the one we recently developed for excitons interacting with excitons. These techniques allow to take \\emph{exactly} into account the possible exchanges between carriers. We use it to get the $\\mathrm{X}^-$ trion creation operator in terms of exciton and free-electron creation operators. In a last part we generate the ladder diagrams associated to these trions. Although si...

  7. FPGA Implementations of Ladder Diagrams

    Directory of Open Access Journals (Sweden)

    Neil William Bergmann

    2013-02-01

    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.

  8. Fish-Friendly Engineering

    Science.gov (United States)

    Integrated Teaching and Learning Program,

    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.

  9. Integral representations combining ladders and crossed-ladders

    CERN Document Server

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

    2014-01-01

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

  10. A Review and Modern Approach to LC Ladder Synthesis

    Directory of Open Access Journals (Sweden)

    Alexander J. Casson

    2011-01-01

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

  11. Transformations of triangle ladder diagrams

    Science.gov (United States)

    Kondrashuk, Igor; Vergara, Alvaro

    2010-03-01

    It is shown how dual space diagrammatic representation of momentum integrals corresponding to triangle ladder diagrams with an arbitrary number of rungs can be transformed to half-diamonds. In paper arXiv:0803.3420 [hep-th] the half-diamonds were related by conformal integral substitution to the diamonds which represent the dual space image of four-point ladder integrals in the four-dimensional momentum space. Acting in the way described in the present paper we do not need to use the known result for diamond (four-point) diagrams as an external input in deriving relations of arXiv:0803.3420 [hep-th], however, that result for the diamond diagram arises in the present proof as an intermediate consequence in a step-by-step diagrammatic transformation from the triangle ladder diagram to the half-diamond diagrams.

  12. Semiclassical description of spin ladders

    CERN Document Server

    Sénéchal, D

    1995-01-01

    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.

  13. Transformations of triangle ladder diagrams

    OpenAIRE

    Kondrashuk, Igor; Vergara, Alvaro

    2009-01-01

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

  14. Transformations of triangle ladder diagrams

    CERN Document Server

    Kondrashuk, Igor

    2009-01-01

    It is shown how dual space diagrammatic representation of momentum integrals corresponding to triangle ladder diagrams with an arbitrary number of rungs can be transformed to half-diamonds. Acting in the way described in this paper we do not need to use diamond (four-point) diagrams as an intermediate step in deriving relations of arXiv:0803.3420 [hep-th]. In that paper the half-diamonds were related by conformal integral substitution to the diamonds. As is known, the diamonds represent the dual space image of four-point ladder integrals in the four-dimensional momentum space.

  15. Thiophene-phenylene/naphthalene-based step-ladder copolymers

    OpenAIRE

    Bu?nnagel, Torsten W.; Nehls, Benjamin S.; Galbrecht, Frank; Schottler, Kristina; Kudla, Christof J.; Volk, Markus; Pina, Joa?o; Melo, Joa?o S. Seixas; Burrows, Hugh D.; Scherf, Ullrich

    2008-01-01

    A series of step-ladder copolymers based on thiophene-phenylene-thiophene SL1-SL3 and thiophene-naphthylene-thiophene SL4 repeat units with varying lengths of the oligothiophene segment has been designed and synthesized via a microwave-assisted Stille-type cross-coupling reaction followed by a polymer-analogous cyclization reaction. The optical properties of the step-ladder copolymers have been investigated in detail, in particular at low temperature and in the solid-state. © 2008 Wiley Peri...

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

    Scientific Electronic Library Online (English)

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

    2008-03-01

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

  17. Laddering em pesquisa de marketing Laddering in marketing research

    Directory of Open Access Journals (Sweden)

    Tânia Modesto Veludo-de-Oliveira

    2008-03-01

    Full Text Available O artigo discute a técnica de pesquisa laddering em marketing, considerando a proposta de renovação de conhecimentos sobre metodologia na área. Para isso investiga diversos estudos, artigos e pesquisas que tratam do assunto em nível nacional e internacional. O conceito de cadeias meios-fins é 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Murarka, I.P.; Bodeau, D.J.

    1977-01-01

    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.

  19. 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

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

    Science.gov (United States)

    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

    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

  1. Ladder-Type Circuits Revisited

    Science.gov (United States)

    Yoon, Sung Hyun

    2007-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Mauro Barbosa Terra

    2009-01-01

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

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

    OpenAIRE

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

    2012-01-01

    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 ...

  4. Comprehensive FISH probe design tool applied to imaging human immunoglobulin class switch recombination.

    Science.gov (United States)

    Nedbal, Jakub; Hobson, Philip S; Fear, David J; Heintzmann, Rainer; Gould, Hannah J

    2012-01-01

    We present a web engine boosted fluorescence in-situ hybridization (webFISH) algorithm using a genome-wide sequence similarity search to design target-specific single-copy and repetitive DNA FISH probes. The webFISH algorithm featuring a user-friendly interface (http://www.webfish2.org/) maximizes the coverage of the examined sequences with FISH probes by considering locally repetitive sequences absent from the remainder of the genome. The highly repetitive human immunoglobulin heavy chain sequence was analyzed using webFISH to design three sets of FISH probes. These allowed direct simultaneous detection of class switch recombination in both immunoglobulin-heavy chain alleles in single cells from a population of cultured primary B cells. It directly demonstrated asynchrony of the class switch recombination in the two alleles in structurally preserved nuclei while permitting parallel readout of protein expression by immunofluorescence staining. This novel technique offers the possibility of gaining unprecedented insight into the molecular mechanisms involved in class switch recombination. PMID:23272136

  5. NUCLEON ASIC and ladder electronics for cosmic ray experiments

    Science.gov (United States)

    Atkin, E.; Voronin, A.; Bulatov, V.; Dorokhov, V.; Karmanov, D.; Kovalev, I.; Kudryashov, I.; Podorozhniy, D.; Polkov, D.; Filippov, S.; Shumikhin, V.

    2015-04-01

    The 32-channels ASIC with a unique dynamic range from 1 to 40000 mips, signal to noise ratio not less than 2.5 at a shaper peaking time of 2 ? s and a low power consumption of 1.5 mW/channel has been designed. The transfer function of the charge sensitive amplifier (CSA), having two subranges of various gains, allowed to reach high dynamic range of the readout electronics. The subranges are automatically switched. Two ASICs were installed on a ladder construction which also contains an ADC, a microprocessor and a power supply. The ASIC and the ladder were created for the minicalorimeter of the NUCLEON experiment. The goal of the NUCLEON satellite mission is to measure the elemental (Z from 1 to 30) energy spectra of high-energy (1011-1015 eV) cosmic rays. The ladder has been tested at the SPS. The ladder can also be used for other future HEP and space cosmic ray experiments.

  6. Research to improve extension ladder angular positioning.

    Science.gov (United States)

    Simeonov, P; Hsiao, H; Powers, J; Kim, I-J; Kau, T-Y; Weaver, D

    2013-05-01

    A leading cause for extension ladder fall incidents is a slide-out event usually related to suboptimal ladder inclination. An improved ladder positioning method or procedure could reduce the risk of ladder stability failure and the related fall injury. The objective of the study was to comparatively evaluate the effectiveness of a multimodal angle indicator with other existing methods for extension ladder angular positioning. Twenty experienced and 20 inexperienced ladder users participated in the study. Four ladder positioning methods were tested in a controlled laboratory environment with 4.88 m (16 ft) and 7.32 m (24 ft) ladders in extended and retracted positions. The positioning methods included a no-instruction method, the current standard anthropometric method, and two instrumental methods - a bubble level indicator, and a multimodal indicator providing direct feedback with visual and sound signals. Performance measures included positioning angle and time. The results indicated that the anthropometric method was effective in improving the extension ladder positioning angle (p < 0.001); however, it was associated with considerable variability and required 50% more time than no-instruction. The bubble level indicator was an accurate positioning method (with very low variability), but required more than double the time of the no-instruction method (p < 0.001). The multimodal indicator improved the ladder angle setting as compared to the no-instruction and anthropometry methods (p < 0.001) and required the least time for ladder positioning among the tested methods (p < 0.001). An indicator with direct multimodal feedback is a viable approach for quick and accurate ladder positioning. The main advantage of the new multimodal method is that it provides continuous feedback on the angle of the device and hence does not require repositioning of the ladder. Furthermore, this indicator can be a valuable tool for training ladder users to correctly apply the current ANSI A14 standard anthropometric method in ladder angular positioning. The multimodal indicator concept has been further developed to become a hand-held tool in the form of a smart phone application. PMID:23177178

  7. Make a Human Scale Ladder

    Science.gov (United States)

    Twin Cities Public Television, Inc.

    2008-01-01

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

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

    Science.gov (United States)

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

  9. Evaluation of Utah Career Ladder Programs.

    Science.gov (United States)

    Horan, Carolyn B.; Lambert, Vicki

    This report recounts the establishment of the Utah Career Ladder Program, reviews findings from prior evaluations of the program, and describes in detail the 1993 evaluation authorized by the Utah State Legislature. The report also covers questions about the impact of the program in general. Chapter 1 provides a history of the Utah Career Ladder

  10. Universality Classes of Diagonal Quantum Spin Ladders

    CERN Document Server

    Martín-Delgado, M A; Sierra, G

    2004-01-01

    We find the classification of diagonal spin ladders depending on a characteristic integer $N_p$ in terms of ferrimagnetic, gapped and critical phases. We use the finite algorithm DMRG, non-linear sigma model and bosonization techniques to prove our results. We find stoichiometric contents in cuprate $CuO_2$ planes that allow for the existence of weakly interacting diagonal ladders.

  11. 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)

  12. 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

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

    Directory of Open Access Journals (Sweden)

    Bikash Sarkar

    2013-02-01

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

  14. Box ladders in non-integer dimension

    OpenAIRE

    Gonzalez, Ivan; Kondrashuk, Igor

    2012-01-01

    We construct a family of triangle-ladder diagrams which may be calculated by making use of Belokurov-Usyukina loop reduction technique in d = 4 -2e dimensions. The main idea of the approach proposed in the present paper consists in generalization of this loop reduction technique existing in d = 4 dimensions. The recursive formula relating the result for L-loop triangle ladder diagram of this family and the result for (L-1)-loop triangle ladder diagram of the same family is d...

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

    Directory of Open Access Journals (Sweden)

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

    2015-02-01

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

  16. Centipede ladder at quarter filling

    CERN Document Server

    Aristov, D N; Kikoin, K

    2007-01-01

    We study the ground state and excitation spectrum of a quasi one-dimensional nanostructure consisting of a pole and rungs oriented in the opposite directions ("centipede ladder", CL) at quarter filling. The spin and charge excitation spectra are found in the limits of small and large longitudinal hopping $t_\\|$ compared to the on-rung hopping rate $t_\\perp$ and exchange coupling $I_\\perp$. At small $t_\\|$ the system with ferromagnetic on-rung exchange demonstrates instability against dimerization. Coherent propagation of charge transfer excitons is possible in this limit. At large $t_\\|$ CL behaves like two-orbital Hubbard chain, but the gap opens in the charge excitation spectrum thus reducing the symmetry from SU(4) to SU(2). The spin excitations are always gapless and their dispersion changes from quadratic magnon-like for ferromagnetic on-rung exchange to linear spinon-like for antiferromagnetic on-rung exchange in weak longitudinal hopping limit.

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

    OpenAIRE

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

    2000-01-01

    A comprehensive theoretical and experimental study is presented of the magnetic susceptibility versus temperature \\chi(T) of spin S = 1/2 two- and three-leg Heisenberg ladders and ladder oxide compounds. Extensive quantum Monte Carlo simulations of \\chi(T) were carried out for both isolated and coupled two-leg ladders with spatially anisotropic intraladder exchange. Accurate fits to these and related literature QMC data were obtained. We have also calculated the one- and two...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Marcia Regina Simões

    2011-06-01

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

  20. A seventeenth-order polylogarithm ladder

    CERN Document Server

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

    1999-01-01

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

  1. 29 CFR 1910.27 - Fixed ladders.

    Science.gov (United States)

    2010-07-01

    ...installation. This substandard pitch range shall be considered as a critical range to be avoided, if possible. (3) Scope of coverage in this section. This...only fixed ladders within the pitch range of 60 degrees and 90 degrees with...

  2. Observation of breathers in Josephson ladders

    CERN Document Server

    Binder, P; Ustinov, A V; Flach, S; Zolotaryuk, Y

    2000-01-01

    We report on the observation of spatially-localized excitations in a ladder of small Josephson junctions. The excitations are whirling states which persist under a spatially-homogeneous force due to the bias current. These states of the ladder are visualized using a low temperature scanning laser microscopy. We also compute breather solutions with high accuracy in corresponding model equations. The stability analysis of these solutions is used to interpret the measured patterns in the I-V characteristics.

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

    Science.gov (United States)

    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

    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. PMID:25430138

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

    Scientific Electronic Library Online (English)

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

    2006-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-04

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

  6. Doped spin ladders under magnetic field

    International Nuclear Information System (INIS)

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

  7. Artificial ladder-shaped polyethers that inhibit maitotoxin-induced Ca2+ influx in rat glioma C6 cells.

    Science.gov (United States)

    Oishi, Tohru; Konoki, Keiichi; Tamate, Rie; Torikai, Kohei; Hasegawa, Futoshi; Matsumori, Nobuaki; Murata, Michio

    2012-06-01

    Maitotoxin (MTX) is a ladder-shaped polyether produced by the epiphytic dinoflagellate Gambierdiscus toxicus. It is known to elicit potent toxicity against mammals and induce influx of Ca(2+) into cells. An artificial ladder-shaped polyether possessing a 6/7/6/6/7/6/6 heptacyclic ring system, which was designed for elucidating interactions with transmembrane proteins, was found to be the most potent inhibitor against MTX-induced Ca(2+) influx that has ever been reported. PMID:22560474

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

    Scientific Electronic Library Online (English)

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

    2014-06-01

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

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

    Science.gov (United States)

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

    2014-11-25

    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 ecological, socioeconomic and management contexts. PMID:25423947

  10. Performance Assessment Techniques for Teacher Career Ladder Advancement.

    Science.gov (United States)

    Burke, Peter; Lind, Kathryn G.

    1987-01-01

    Describes the career ladder program developed for Wisconsin teachers. Includes a description of the requirements for advancement, the performance assessment component, and the different steps in the career ladder. Includes two figures. (MD)

  11. 5 CFR 335.104 - Eligibility for career ladder promotion.

    Science.gov (United States)

    2010-01-01

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

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

    Directory of Open Access Journals (Sweden)

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

    2010-10-01

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

  13. Honeycomb Heisenberg Spin Ladder: Unusual Ground State and Thermodynamic Properties

    OpenAIRE

    Zhao, Yang; Wei LI; Xi, Bin; Ran, Shi-Ju; Zhu, Yuan-Yuan; Wang, Bing-Wu; Gao, Song; Su, Gang

    2013-01-01

    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, ...

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

    OpenAIRE

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

    2010-01-01

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

  15. The Static Ladder Problem with Two Sources of Friction

    Science.gov (United States)

    Bennett, Jonathan; Mauney, Alex

    2011-01-01

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

  16. Non-Abelian String-Net Ladders

    CERN Document Server

    Schulz, M D; Vidal, J

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Praween K. Sinha

    2014-11-01

    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.

  18. Simulation of TunneLadder Traveling-Wave Tube Input/Output Coupler Characteristics Using MAFIA

    Science.gov (United States)

    Kory, Carol L.; Qureshi, A. Haq

    1996-01-01

    RF input/output coupler characteristics for the TunneLadder traveling-wave tube have been calculated using the three-dimensional computer code, MAFIA and compared to experimental data with good agreement. Theory behind coupling of the TunneLadder interaction circuit to input and output waveguides is presented and VSWR data is calculated for variations on principal coupler dimensions to provide insight into manufacturing tolerances necessary for acceptable performance. Accuracy of results using MAFIA demonstrates how experimental hardware testing of three-dimensional coupler designs can be reduced.

  19. Raman cross section of spin ladders

    OpenAIRE

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

    2001-01-01

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

  20. Mott-Superfluid transition in bosonic ladders

    OpenAIRE

    Donohue, P.; Giamarchi, T.

    2001-01-01

    We show that in a commensurate bosonic ladder, a quantum phase transition occurs between a Mott insulator and a superfluid when interchain hopping increases. We analyse the properties of such a transition as well as the physical properties of the two phases. We discuss the physical consequences for experimental systems such as Josephson Junction arrays.

  1. From quantum ladder climbing to classical autoresonance

    Science.gov (United States)

    Marcus, G.; Friedland, L.; Zigler, A.

    2004-01-01

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

  2. Ladder-structured photonic variable delay device

    Science.gov (United States)

    Yao, X. Steve (Inventor)

    1998-01-01

    An ladder-structured variable delay device for providing variable true time delay to multiple optical beams simultaneously. The device comprises multiple basic units stacked on top of each other resembling a ladder. Each basic unit comprises a polarization sensitive corner reflector formed by two polarization beamsplitters and a polarization rotator array placed parallel to the hypotenuse of the corner reflector. Controlling an array element of the polarization rotator array causes an optical beam passing through the array element to either go up to a basic unit above it or reflect back towards output. The beams going higher on the ladder experience longer optical path delay. Finally, the ladder-structured variable device can be cascaded with another multi-channel delay device to form a new device which combines the advantages of the two individual devices. This programmable optic device has the properties of high packing density, low loss, easy fabrication, and virtually infinite bandwidth. In addition, the delay is reversible so that the same delay device can be used for both antenna transmitting and receiving.

  3. Box ladders in a noninteger dimension

    Science.gov (United States)

    Gonzalez, I.; Kondrashuk, I. N.

    2013-11-01

    We construct a family of triangle-ladder diagrams that can be calculated using the Belokurov-Usyukina loop reduction technique in d= 4-2? dimensions. The main idea of the approach we propose is to generalize this loop reduction technique existing in d= 4 dimensions. We derive a recurrence relation between the result for an L-loop triangle-ladder diagram of this family and the result for an (L- 1)-loop triangleladder diagram of the same family. Because the proposed method combines analytic and dimensional regularizations, we must remove the analytic regularization at the end of the calculation by taking the double uniform limit in which the parameters of the analytic regularization vanish. In the position space, we obtain a diagram in the left-hand side of the recurrence relations in which the rung indices are 1 and all other indices are 1 - ? in this limit. Fourier transforms of diagrams of this type give momentum space diagrams with rung indices 1 - ? and all other indices 1. By a conformal transformation of the dual space image of this momentum space representation, we relate such a family of triangle-ladder momentum diagrams to a family of box-ladder momentum diagrams with rung indices 1 - ? and all other indices 1. Because any diagram from this family is reducible to a one-loop diagram, the proposed generalization of the Belokurov-Usyukina loop reduction technique to a noninteger number of dimensions allows calculating this family of box-ladder diagrams in the momentum space explicitly in terms of Appell's hypergeometric function F 4 without expanding in powers of the parameter ? in an arbitrary kinematic region in the momentum space.

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

    Science.gov (United States)

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

    2015-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Scruton, D. A.; Goosney, R. G. [Fisheries and Oceans Canada, Science Branch, St. John`s, NF (Canada); McKinley, R. S.; Booth, R. K.; Peake, S. [Waterloo Univ., Biotelemetry Institute, Waterloo, ON (Canada)

    1998-08-01

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

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

    International Nuclear Information System (INIS)

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

  7. Stripe formation in doped Hubbard ladders

    CERN Document Server

    Hager, G; Jeckelmann, E; Fehske, H

    2004-01-01

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

  8. The spin-1 ladder A bosonization study

    CERN Document Server

    Allen, D

    2000-01-01

    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.

  9. Entanglement spectra of quantum Heisenberg ladders

    OpenAIRE

    Poilblanc, Didier

    2010-01-01

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

  10. d -wave superconductivity in coupled ladders

    Science.gov (United States)

    Faye, J. P. L.; Hassan, S. R.; Sriluckshmy, P. V.; Baskaran, G.; Sénéchal, D.

    2015-05-01

    We study the one-band Hubbard model on the trellis lattice, a two-dimensional frustrated lattice of coupled two-leg ladders, with hopping amplitude t within ladders and t' between ladders. For large U /t this is a model for the cuprate Sr14 -xCaxCu24O41 . We investigate the phase diagram as a function of doping for U =10 t using two quantum cluster methods: The variational cluster approximation (VCA), with clusters of sizes 8 and 12, and cellular dynamical mean field theory (CDMFT), both at zero temperature. Both methods predict a superconducting dome, ending at roughly 20% doping in VCA and 15% in CDMFT. In VCA, the superconducting order parameter is complex in a range of doping centered around 10%, corresponding to bulk chiral, T -violating superconductivity. However, the CDMFT solution is not chiral. We find evidence for a migration of the Cooper pairs from the interladder region towards the plaquettes as doping is increased.

  11. Stark-ladder resonances in piezoelectric composites

    Science.gov (United States)

    Monsivais, G.; Rodríguez-Ramos, R.; Esquivel-Sirvent, R.; Fernández-Alvarez, L.

    2003-11-01

    In this paper we introduce a piezoelectric composite medium. The composite shows a series of resonances similar to the Stark-ladder resonances originally observed in the propagation of electrons through crystals in a dc electric field. These resonances appear when shear horizontal and surface waves propagate through a special piezoelectric composite medium consisting of N piezoelectric layers, each layer being a material of hexagonal 6mm symmetry. For periodic piezocomposites, we obtain a band structure as expected. However, when the periodicity is broken by adding a linear term in the values of the piezoelectric parameters of the layers, the band structure is destroyed and, in certain cases, resonances of Stark-ladder type appear instead. A 4×4 transfer matrix approach is used to calculate the response of the composite under electromechanical perturbations. The response is studied as a function of the properties of the different materials, width of the layers, wave frequency, and angle of incidence. Numerical results for the electric potential and for the displacement of the surface of the last layer of the composite are presented showing the existence of Stark-ladder resonances.

  12. Box ladders in non-integer dimension

    CERN Document Server

    Gonzalez, Ivan

    2012-01-01

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

  13. Braess like Paradox on Ladder Network

    CERN Document Server

    Toyota, Norihito

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Sheng Chih Shen

    2013-03-01

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

  15. 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.

  16. Effects of uniaxial pressure in cuprate ladder compound

    Science.gov (United States)

    Hori, H.; Sasagawa, T.; Misawa, M.; Takagi, H.

    2005-04-01

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

  17. A Dream or Jacob's Ladder

    OpenAIRE

    Geddes, Wilhelmina Margaret (Irish glass painter, illustrator, decorative artist, 1887-1955)

    1987-01-01

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

  18. 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)

    Hildebrand, S.G. (ed.)

    1980-08-01

    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.

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

    International Nuclear Information System (INIS)

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

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

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

  1. Education System and the "Ladder of Success"

    OpenAIRE

    Ueda, Akiko

    2004-01-01

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

  2. Polar molecules in frustrated triangular ladders

    Science.gov (United States)

    Mishra, Tapan; Greschner, Sebastian; Santos, Luis

    2015-04-01

    Polar molecules in geometrically frustrated lattices may result in a very rich landscape of quantum phases, due to the nontrivial interplay between frustration, and two- and possibly three-body intersite interactions. In this paper we illustrate this intriguing physics for the case of hard-core polar molecules in frustrated triangular ladders. Whereas commensurate lattice fillings result in gapped phases with bond order and/or density-wave order, at incommensurate fillings we find chiral, two-component, and pair superfluids. We show as well that, remarkably, polar molecules in frustrated lattices allow for the observation of bond-ordered supersolids.

  3. Effects of the Missouri Career Ladder Program on Teacher Mobility

    Science.gov (United States)

    Booker, Kevin; Glazerman, Steven

    2009-01-01

    One goal of Missouri's Career Ladder program (CL) is to help school districts that have difficulty retaining teachers, particularly those that are small and rural, by offering their teachers opportunities to earn extra pay for extra work and professional development. This report seeks to estimate the effect Career Ladder Program has had on…

  4. Discussing Laddering Application by the Means-End Chain Theory

    Science.gov (United States)

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

    2006-01-01

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

  5. Visualization, analysis, and design of COMBO-FISH probes in the grid-based GLOBE 3D genome platform.

    Science.gov (United States)

    Kepper, Nick; Schmitt, Eberhard; Lesnussa, Michael; Weiland, Yanina; Eussen, Hubert B; Grosveld, Frank G; Hausmann, Michael; Knoch, Tobias A

    2010-01-01

    The genome architecture in cell nuclei plays an important role in modern microscopy for the monitoring of medical diagnosis and therapy since changes of function and dynamics of genes are interlinked with changing geometrical parameters. The planning of corresponding diagnostic experiments and their imaging is a complex and often interactive IT intensive challenge and thus makes high-performance grids a necessity. To detect genetic changes we recently developed a new form of fluorescence in situ hybridization (FISH) - COMBinatorial Oligonucleotide FISH (COMBO-FISH) - which labels small nucleotide sequences clustering at a desired genomic location. To achieve a unique hybridization spot other side clusters have to be excluded. Therefore, we have designed an interactive pipeline using the grid-based GLOBE 3D Genome Viewer and Platform to design and display different labelling variants of candidate probe sets. Thus, we have created a grid-based virtual "paper" tool for easy interactive calculation, analysis, management, and representation for COMBO-FISH probe design with many an advantage: Since all the calculations and analysis run in a grid, one can instantly and with great visual ease locate duplications of gene subsequences to guide the elimination of side clustering sequences during the probe design process, as well as get at least an impression of the 3D architectural embedding of the respective chromosome region, which is of major importance to estimate the hybridization probe dynamics. Beyond, even several people at different locations could work on the same process in a team wise manner. Consequently, we present how a complex interactive process can profit from grid infrastructure technology using our unique GLOBE 3D Genome Platform gateway towards a real interactive curative diagnosis planning and therapy monitoring. PMID:20543436

  6. Interacting antikinks on a diamondback ladder II

    Science.gov (United States)

    Shtengel, Kirill; Tovar, Mayra

    2011-03-01

    Recently introduced ``antikinks'' are spin 1/2 excitations of the Heisenberg antiferromagnet on a sawtooth lattice. The idea is that they mimic spinons of the kagome antiferromagnet. Antikinks are triangles of spins which are not in their ground state. Treating antikinks as free non-interacting particles (a good approximation for the sawtooth chain), their energy was found to be substantially reduced by delocalization. We study antikinks on a ``diamondback'' ladder in which all spins are shared between two triangles. Consequently, in a uniform case the concentration of antikinks becomes 1/4 and they strongly interact, making such a model a much better approximation for the kagome case. We treat these effects perturbatively by allowing different Heisenberg couplings on the up- and downward oriented triangles, the two limiting cases being the sawtooth and uniform diamondback ladder. We find a non-monotonic, power-law decay of induced interactions between the antikinks with their separation. The consequences of these interactions will be discussed in this talk.

  7. Interacting antikinks on a diamondback ladder I

    Science.gov (United States)

    Tovar, Mayra; Shtengel, Kirill

    2011-03-01

    Recently introduced ``antikinks'' are spin 1/2 excitations of the Heisenberg antiferromagnet on a sawtooth lattice. The idea is that they mimic spinons of the kagome antiferromagnet. Antikinks are triangles of spins which are not in their ground state. Treating antikinks as free non- interacting particles (a good approximation for the sawtooth chain), their energy was found to be substantially reduced by delocalization. We study antikinks on a ``diamondback'' ladder in which all spins are shared between two triangles. Consequently, in a uniform case the concentration of antikinks becomes 1/4 and they strongly interact, making such a model a much better approximation for the kagome case. We treat these effects perturbatively by allowing different Heisenberg couplings on the up- and downward oriented triangles, the two limiting cases being the sawtooth and uniform diamondback ladder. We find a non-monotonic, power-law decay of induced interactions between the antikinks with their separation. The consequences of these interactions will be discussed in this talk.

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

    Directory of Open Access Journals (Sweden)

    Alison M. Hutson

    2012-10-01

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

  9. Quantifying Ladder Fuels: A New Approach Using LiDAR

    Directory of Open Access Journals (Sweden)

    Heather A. Kramer

    2014-06-01

    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.

  10. Ladder Climbing and Autoresonant Acceleration of Plasma Waves

    CERN Document Server

    Barth, Ido; Fisch, Nathaniel J

    2015-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chamness, Mickie A. [Pacific Northwest National Laboratory

    2008-08-29

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

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

    OpenAIRE

    Nieuwenhuis, Taco; Tjon, J. A.

    1996-01-01

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

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

    Scientific Electronic Library Online (English)

    Marlene Sofia, Arcifa; André Luiz Henríques, Esguícero.

    2012-10-01

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

  14. 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

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

    OpenAIRE

    Hutson, Alison M.; Lawrence Valenzuela; Douglas Tave; Louie Toya

    2012-01-01

    This article describes an airlift pump used to produce a circular flow in a fish culture tank that does not attach to the tank. The design produces an airlift pump that does not swing back and forth or float upwards while in use. It is easy to build, inexpensive, and can be quickly installed and removed so that it does not interfere with sampling or harvest. The airlift pump was evaluated during a 30-d survival trial with the endangered Rio Grande silvery minnow (Hybognathus amarus) in 2.44-m...

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

    Science.gov (United States)

    Powell, Martin

    2014-01-01

    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

  17. The ladder problem: Painleve integrability and explicit solution

    International Nuclear Information System (INIS)

    We consider the n-dimensional ladder system, that is the homogeneous quadratic system of first-order differential equations of the form x-doti xi?j=1naijxj,i = 1,n, where (aij) = (i + 1 - j), i, j = 1, n, introduced by Imai and Hirata (2002 Preprint nlin.SI/0212007 v1 3). The ladder system is found to be integrable for all n in terms of the Painleve analysis and its solution is explicitly given

  18. Spin-charge separation in strongly interacting finite ladder rings

    OpenAIRE

    Rincon, Julian; Hallberg, K.; Aligia, A. A.

    2008-01-01

    We study the conductance through Aharonov-Bohm finite ladder rings with strongly interacting electrons, modelled by the prototypical t-J model. For a wide range of parameters we observe characteristic dips in the conductance as a function of magnetic flux, predicted so far only in chains which are a signature of spin and charge separation. These results open the possibility of observing this peculiar many-body phenomenon in anisotropic ladder systems and in real nanoscopic d...

  19. Straightforward Procedure for Laboratory Production of DNA Ladder

    OpenAIRE

    Vo Thi Thuong Lan; Pham Thi Thanh Loan; Pham Anh Thuy Duong; Le Thi Thanh; Ngo Thi Ha; Ta Bich Thuan

    2012-01-01

    DNA ladder is commonly used to determine the size of DNA fragments by electrophoresis in routine molecular biology laboratories. In this study, we report a new procedure to prepare a DNA ladder that consists of 10 fragments from 100 to 1000?bp. This protocol is a combination of routinely employed methods: cloning, PCR, and partial digestion with restriction enzymes. DNA fragments of 100?bp with unique restriction site at both ends were self-ligated to create a tandem repeat. Once being cl...

  20. Instabilities of coupled Cu2O5 ladders

    Science.gov (United States)

    Schuetz, Florian; Marston, Brad

    2008-03-01

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

  1. Giant Stark effect in double-stranded porphyrin ladder polymers

    Science.gov (United States)

    Pramanik, Anup; Kang, Hong Seok

    2011-03-01

    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.

  2. Formulation and characterization of an experimental PCB mixture designed to mimic human exposure from contaminated fish.

    Science.gov (United States)

    Kostyniak, Paul J; Hansen, Larry G; Widholm, John J; Fitzpatrick, Rich D; Olson, James R; Helferich, Jennifer L; Kim, Kyung Ho; Sable, Helen J K; Seegal, Rich F; Pessah, Isaac N; Schantz, Susan L

    2005-12-01

    Each environmental exposure matrix contains a unique mixture of PCB congeners. Since several congener types have multiple and distinct biological actions, it is important to characterize congener profiles in exposure sources. The Fox River Environment and Diet Study (FRIENDS) is assessing the human health effects of consumption of PCB-contaminated fish from the Fox River in northeastern Wisconsin. Concurrent laboratory studies required the formulation of a dosing solution which closely mimicked the human PCB exposure from fish. PCB congener profiles from Fox River walleye were compared to profiles for various theoretical mixtures having different relative percentages of Aroclors by weight. The theoretical mixture which provided the best approximation of the Fox River fish PCB profile contained 35% 1242, 35% 1248, 15% 1254, and 15% 1260. A PCB mixture was formulated to match this theoretical construct, and the congener profile for the mixture of Aroclors was determined by capillary column gas chromatography with electron capture detection (GC/ECD). The relative percent of each congener was compared to the PCB congener profile of the theoretical Aroclor mixture and that for Fox River walleye. The specific congeners differed on average by 17% from the theoretical Aroclor mixture predicted values, and the specific congeners measured in the mixture were on average within 71% of those reported for Fox River fish. The mixture was found to have relatively low AhR activity but high RyR activity. Indirect comparisons suggest that in vivo toxicity was slightly greater than that for Aroclor 1254. This illustrates that Aroclor mixtures are useful for formulating dosing solutions which closely approximate actual environmental exposures. PMID:16177234

  3. Ladder Operators for Lamé Spheroconal Harmonic Polynomials

    Directory of Open Access Journals (Sweden)

    Ricardo Méndez-Fragoso

    2012-10-01

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

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

    Scientific Electronic Library Online (English)

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

    2012-10-01

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

  5. Spin and thermal conductivity of quantum spin chains and ladders

    Science.gov (United States)

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

    2015-03-01

    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.

  6. Ladder polymers for use as high temperature stable resins or coatings

    Science.gov (United States)

    Meador, Mary Ann (inventor)

    1990-01-01

    An object of the invention is to synthesize a new class of ladder and partial ladder polymers. In accordance with the invention, the new class of ladder and partial ladder polymers are synthesized by polymerizing a bis-dienophile with a bis-diene. Another object of the invention is to provide a fabricated, electrically conducting, void free composite comprising the new class of the ladder and partial ladder polymers described above. The novelty of the invention relates to a new class of ladder and partial ladder polymers and a process for synthesizing these polymers. These polymers are soluble in common organic solvents and are characterized with a unique dehydration property at temperatures of 300 to 400 C to provide thermo-oxidatively stable pentiptycene units along the polymeric backbone. These polymers are further characterized with high softening points and good thermo-oxidative stability properties. Thus these polymers have potential as processable, matrix resins for high temperature composite applications.

  7. Downstream fish passage on Black River system

    International Nuclear Information System (INIS)

    Downstream fish passage of juvenile alewife at the Black River hydroelectric system has traditionally been directed by a major screen assembly to a route avoiding altogether four out of five small hydroelectric power plants. This system includes retention of larvae/juveniles in a lake until mid July, diversion of fish via a major screen assembly and by-passing of a station using a fish ladder. However, difficulties with the arrangement have resulted in increasing numbers of fish passing by all five stations. A second option which reduces labour and maintenance activities and promotes increased growth of fish as they pass from reservoir to reservoir involves use of simple fishways coupled with fish pulsers to deflect fish from the station intakes. The fish pulsers use 100 Hz frequency at 20 pulses per minute placed directly in front of the station intake at a depth of 3 m. Both strategies have contributed to increased fish production and migration such that the present run is 5 million to 8 million fish. 4 refs., 4 figs

  8. Edge-reinforced random walk on a ladder

    CERN Document Server

    Merkl, F; Merkl, Franz; Rolles, Silke

    2005-01-01

    We prove that the edge-reinforced random walk on the ladder Z x {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 multi-component Gibbsian process. A transfer operator technique and entropy estimates from statistical mechanics are used to analyse this Gibbsian process. Furthermore, we prove spatially exponentially fast decreasing bounds for normalized local times of the edge-reinforced random walk on a finite piece of the ladder, uniformly in the size of the finite piece.

  9. From the Hubbard to the SO(5) Ladder A Numerical Study

    CERN Document Server

    Duffy, D; Kim, E; Duffy, Daniel; Haas, Stephan; Kim, Eugene

    1999-01-01

    The Hubbard Hamiltonian on a two-chain ladder is studied numerically using quantum Monte Carlo and Exact Diagonalization techniques. A rung interaction, $V$, is turned on such that the resulting model has an exact SO(5) symmetry when $V=-U$. The evolution of the low energy excitation spectrum is presented from the pure Hubbard ladder to the SO(5) ladder. It is shown that the low energy excitations in the pure Hubbard ladder have an approximate SO(5) symmetry.

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

    Science.gov (United States)

    Air Force Occupational Measurement Center, Lackland AFB, TX.

    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…

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

    Directory of Open Access Journals (Sweden)

    Maref Y. Alzoubi

    2005-08-01

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

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

    OpenAIRE

    Alzoubi, Maref Y.; Jaradat, M. M. M.

    2005-01-01

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

  13. Equivalent Resistance of 5×n-laddered Network

    Directory of Open Access Journals (Sweden)

    Xingpeng Yang

    2010-06-01

    Full Text Available The The basic structure of 5×n -step network was studied by matrix transform method. Thus, the resistances of both the infinite and finite network were obtained. In addition, the resistances of the finite 5×n -laddered network were measured experimentally by NI Multisim 10 when n equals to positive integer such as one,two,three ... ,and so on. It is found that the measured values of the equivalent resistances of finite 5×n-laddered networks are consistent with the calculated ones.

  14. Notebook Positioning by Perceptual Map and Laddering Method

    Directory of Open Access Journals (Sweden)

    Mehdi Zaribaf

    2012-01-01

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

  15. Edge-reinforced random walk on a ladder

    OpenAIRE

    Merkl, F.; Rolles, Sww

    2005-01-01

    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...

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

    CERN Document Server

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

    2012-01-01

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

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

    LENUS (Irish Health Repository)

    Kennedy, Harry G

    2011-09-01

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

  18. Magnetic properties and quantum entanglement on decorated zigzag ladder

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Boutrup Stephansen, Karen; Mattebjerg, Maria Ahlm

    2015-01-01

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

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

    Science.gov (United States)

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

    2010-09-01

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

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

    International Nuclear Information System (INIS)

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

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

    DEFF Research Database (Denmark)

    Christensen, AsbjØrn; Mosegaard, Henrik

    2009-01-01

    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.

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

    Science.gov (United States)

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

    2015-05-01

    Macrostructures based on natural polymers are subject to large attention, as the application range is wide within the food and pharmaceutical industries. In this study we present nanocomplexes (NCXs) made from electrostatic self-assembly between negatively charged alginate and positively charged fish sarcoplasmic proteins (FSP), prepared by bulk mixing. A concentration screening revealed that there was a range of alginate and FSP concentrations where stable NCXs with similar properties were formed, rather than two exact concentrations. The size of the NCXs was 293±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

  4. 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.

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Nieuwenhuis, T; Nieuwenhuis, Taco

    1996-01-01

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

  7. 29 CFR 1918.24 - Fixed and portable ladders.

    Science.gov (United States)

    2010-07-01

    ...safe and accessible ladder for each gang working in a single hatch. An effective...a 200-pound (890 N) load without deformation. (2) Rungs shall be evenly spaced...250-pound (1,112 N) load without deformation; and (3) Have a minimum...

  8. Insertion and elimination Lie algebra: the ladder case

    CERN Document Server

    Mencattini, I

    2003-01-01

    We prove that insertion-elimination Lie algebra of Feynman graphs, in the ladder case, has a natural interpretation in terms of a certain algebra of infinite dimensional matrices. We study some aspects of its representation theory and we discuss some relations with the representation of the Heisenberg algebra

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

    Science.gov (United States)

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

    2007-01-01

    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…

  10. Spinless Fermionic ladders in a magnetic field: Phase Diagram

    OpenAIRE

    Carr, Sam T.; Narozhny, Boris N.; Nersesyan, Alexander A.

    2006-01-01

    The system of interacting spinless fermions hopping on a two-leg ladder exhibits a series of quantum phase transitions when subjected to an external magnetic field. At half filling, these are either U(1) Gaussian phase transitions between two phases with distinct types of long-range order or Berezinskii-Kosterlitz-Thouless transitions between ordered and gapless phases.

  11. Gevrey formal power series of Wannier-Stark ladders

    International Nuclear Information System (INIS)

    We consider time-independent Schroedinger equations in one dimension with both periodic and Stark potentials. By means of an iterative procedure we obtain a formal power series for the Wannier-Stark ladders. In the case of strongly singular periodic potentials we prove that such a formal power series is of Gevrey type

  12. Color conductivity and ladder summation in hot QCD

    OpenAIRE

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

    2000-01-01

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

  13. Diversity of discrete breathers observed in a Josephson ladder

    CERN Document Server

    Binder, P; Ustinov, A V

    2000-01-01

    We generate and observe discrete rotobreathers in Josephson junction ladders with open boundaries. Rotobreathers are localized excitations that persist under the action of a spatially uniform force. We find a rich variety of stable dynamic states including pure symmetric, pure asymmetric, and mixed states. The parameter range where the discrete breathers are observed in our experiment is limited by retrapping due to dissipation.

  14. Towards flavored bound states beyond rainbows and ladders

    CERN Document Server

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

    2013-01-01

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

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

    CERN Document Server

    Varma, Vipin Kerala

    2013-01-01

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

  16. Dynamic parameterization and ladder operators for the Kratzer molecular potential

    Science.gov (United States)

    Babynanda Devi, O.; Amuba Singh, C.

    2014-09-01

    Introducing independent parameters k and \\delta to represent the strength of the attractive and repulsive components, respectively, we write the Kratzer molecular potential as V\\left( k,\\delta \\right)=({{\\hbar }^{2}}/2\\;m)(-k/r+\\delta (\\delta -1)/{{r}^{2}}). This parameterisation is not only natural, but also convenient for the construction of ladder operators for the system. Adopting the straightforward method of deriving recurrence relations among confluent hypergeometric functions, we construct seven pairs of ladder operators for the Kratzer potential system. Detailed analysis of the laddering actions of these operators is given to show that they connect eigenstates of equal energy but belong to a hierarchy of Kratzer potential systems corresponding to different values of the parameters k and \\delta . Significantly, it is pointed out that it may not be possible to construct, in the position representation, a ladder operator which would connect different eigenstates belonging to the same potential V(k,\\delta ). Transition to the hydrogen atom case is discussed. A number (14 altogether) of functional relations among the confluent hypergeometric functions have been derived and reported separately in an appendix.

  17. Career Ladder Policy for Teachers: The Case of Ghana

    Science.gov (United States)

    Osei, George M.

    2008-01-01

    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…

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

    Science.gov (United States)

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

    2007-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ludwig Chincarini

    2012-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Ayca Kangal

    2013-04-01

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

  1. 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 ...

  2. 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 ...

  3. Improving fish survival through turbines

    International Nuclear Information System (INIS)

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

  4. FishWatch

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

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

    Scientific Electronic Library Online (English)

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

    Full Text Available 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.

  6. Dynamics of a sliding ladder leaning against a wall

    Science.gov (United States)

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

    2015-05-01

    This study is about the dynamics of a sliding ladder leaning against a vertical wall. The results are understood by considering the motion divided in two parts: (i) for 0? t? {{t}s} with one degree of freedom, and (ii) for t>{{t}s} with two degrees of freedom, where the separation is determined by the instance {{t}s}, when the ladder loses its contact with the wall. The observed experimental details are explained by appealing a simple model based on elementary notions of mechanics. We emphasize some features, such as a maximum of the x component of the velocity and of the acceleration of the centre of mass in the first part, and a minimum of the normal reaction force on the floor in the second.

  7. 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.

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

    International Nuclear Information System (INIS)

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

  9. Phase diagram and hidden order for generalized spin ladders

    CERN Document Server

    Brehmer, S; Neugebauer, U

    1996-01-01

    We investigate the phase diagram of antiferromagnetic spin ladders with additional exchange interactions on diagonal bonds by variational and numerical methods. These generalized spin ladders interpolate smoothly between the S=1/2 chain with competing nn and nnn interactions, the S=1/2 chain with alternating exchange and the antiferromagnetic S=1 chain. The Majumdar-Ghosh ground states are formulated as matrix product states and are shown to exhibit the same type of hidden order as the af S=1 chain. Generalized matrix product states are used for a variational calculation of the ground state energy and the spin and string correlation functions. Numerical (Lanczos) calculations of the energies of the ground state and of the low-lying excited states are performed, and compare reasonably with the variational approach. Our results support the hypothesis that the dimer and Majumdar-Ghosh points are in the same phase as the af S=1 chain.

  10. Topological Phase Transition in the Extended Cluster Compass Ladder

    OpenAIRE

    Jafari, R; Mahdavifar, S.

    2013-01-01

    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 ...

  11. Fragility of Symmetry Protected Topological Order on a Hubbard Ladder

    OpenAIRE

    Moudgalya, Sanjay; Pollmann, Frank

    2014-01-01

    Anfuso and Rosch [Phys. Rev. B 75, 144420 (2007)] showed that the "topological" Haldane phase in a fermionic spin-1/2 ladder can be continuously deformed into a "trivial" phase without explicitly breaking symmetries when local charge fluctuations are taken into account. Within the framework of symmetry protected topological phases, we revisit the model and demonstrate how the Haldane phase can be adiabatically connected to a trivial phase due to charge fluctuations. Furtherm...

  12. Experimental Critical Current Patterns in Josephson Junction Ladders

    OpenAIRE

    Binder, P.; Caputo, P.; Fistul, M. V.; Ustinov, A. V.; Filatrella, G.

    2000-01-01

    We present an experimental and theoretical study of the magnetic field dependence of the critical current of Josephson junction ladders. At variance with the well-known case of a one-dimensional (1D) parallel array of Josephson junctions the magnetic field patterns display a single minimum even for very low values of the self-inductance parameter $\\beta_{\\rm L}$. Experiments performed changing both the geometrical value of the inductance and the critical current of the junct...

  13. Laplace-Runge-Lenz vector, ladder operators and supersymmetry

    Energy Technology Data Exchange (ETDEWEB)

    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

    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)

  14. Low-Temperature Properties of the Randomly Depleted Heisenberg Ladder

    OpenAIRE

    Sigrist, M.; Furusaki, A.

    1996-01-01

    Low-temperature thermodynamic properties of the spin-1/2 Heisenberg ladder system with non-magnetic impurities are discussed using an effective Hamiltonian for the impurity-induced spins in the background of a spin liquid with a gap. It is shown that the uniform susceptibility shows Curie-like behavior in high-, intermediate-, and low-temperature regimes, with three different Curie constants. The ratio of specific heat to temperature, C/T, is divergent in the low-temperature...

  15. String order in spin liquid phases of spin ladders

    OpenAIRE

    Fath, G.; Legeza, O.; Solyom, J.

    2003-01-01

    Two-leg spin ladders have a rich phase diagram if rung, diagonal and plaquette couplings are allowed for. Among the possible phases there are two Haldane-type spin liquid phases without local order parameter, which differ, however, in the topology of the short range valence bonds. We show that these phases can be distinguished numerically by two different string order parameters. We also point out that long range string- and dimer orders can coexist.

  16. Improved quantitation of DNA curvature using ligation ladders.

    OpenAIRE

    Ross, E D; Den, R B; Hardwidge, P R; Maher, L. J.

    1999-01-01

    It is often desirable to estimate accurately the local shape of DNA molecules. Such measurements are useful in understanding the intrinsic contribution of DNA sequence to curvature, as well as in assessing the effects of chemical modifications. We have been investigating the effects of asymmetric phosphate neutralization on DNA shape using the well-characterized ligation ladder approach developed by Crothers and co-workers [D.M.Crothers and J.Drak (1992) Meth. Enzymol.,212, 46-71]. This techn...

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

    OpenAIRE

    Varma, Vipin Kerala

    2013-01-01

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

  18. Stability of the Haldane phase in anisotropic magnetic ladders

    OpenAIRE

    Legeza, Ors; Solyom, Jeno

    1998-01-01

    We have considered the properties of anisotropic two-leg ladder models with S=1/2 or S=1 spins on the rungs, using White's density matrix renormalization group method. We have generalized the method by taking into account the symmetries of the model in order to reduce the dimensions of the matrix to be diagonalized, thereby making possible to consider more states. The boundaries in the parameter space of the extended region, where the Haldane phase exists, are estimated.

  19. Unconventional odd-parity superconductivity in the ladder compounds

    OpenAIRE

    Kohmoto, Mahito; Sato*, Masatoshi

    2000-01-01

    Superconductive properties of the two-leg ladder compounds are studied theoretically. The antiferromagnetic fluctuations are considered because of the good nesting of the Fermi surfaces. The attractive interaction which is most likely due to the electron-phonon coupling is also taken into account. Under this circumstance, it is shown that the superconductivity has two sets of spin-triplet pairings. The gaps for both pairings have no node.

  20. Snakes and ladders in an inhomogeneous neural field model

    OpenAIRE

    Avitabile, Daniele; Schmidt, Helmut

    2014-01-01

    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...

  1. Snakes and ladders: localized solutions of plane Couette flow

    CERN Document Server

    Schneider, Tobias M; Burke, John

    2009-01-01

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

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

    OpenAIRE

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

    2011-01-01

    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 followi...

  3. Azygos ladder and looped thoracic duct – a case report

    OpenAIRE

    Kumar N; Sb, Nayak; Shetty S; Sn, Somayaji

    2011-01-01

    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 o...

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

    Science.gov (United States)

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

    1989-11-01

    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

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

    Science.gov (United States)

    Wills, T M; Garing, T L

    1989-11-01

    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

  6. 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)

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

    Directory of Open Access Journals (Sweden)

    Bruno Bordeaux-Rego

    2011-04-01

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

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

    Scientific Electronic Library Online (English)

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

    2011-06-01

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

  9. Room-Temperature Nanoimprinting Using Ladder Hydrogen Silsesquioxane

    Science.gov (United States)

    Nakamatsu, Ken-ichiro; Ishikawa, Kiyoshi; Taneichi, Noriaki; Matsui, Shinji

    2007-08-01

    Ladder hydrogen silsesquioxane (HSQ) has been proposed as a replication material to be used in nanoimprinting processes at room temperature. We replicated ladder-HSQ patterns by nanoimprinting at room temperature that were as accurate as replicated caged-HSQ patterns. Caged HSQ is the standard replication material currently used in nanoimprinting at room temperature. Caged-HSQ-imprinted patterns completely disappeared when annealed at 300 °C. However, ladder-HSQ-imprinted patterns retained almost the same rectangular profile as they had before annealing, even after being subject to high-temperature annealing at 1000 °C. Fourier transform infrared spectroscopy showed that high-temperature annealing transformed the HSQ into a SiOx structure. This vitrification of HSQ resin improved its dry-etching durability, with the dry-etching rate when subject to CHF3 reactive-ion etching decreasing from 32 to 27 nm/min, which is close to the value of 26 nm/min for thermally grown SiO2 and a quartz substrate.

  10. Field induced quantum phase transition in the anisotropic spin ladder

    Energy Technology Data Exchange (ETDEWEB)

    Rezania, Hamed, E-mail: rezania.hamed@gmail.com [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Jesri, Sounya [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of)

    2013-02-15

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

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

    OpenAIRE

    Pal, Biplab; Chakrabarti, Arunava

    2013-01-01

    The energy spectra of quasi-one dimensional quasiperiodic ladder networks are analyzed within a tight binding description. In particular, we show that if a selected set of sites in each strand of a ladder is tunnel-coupled to quantum dots attached from a side, absolutely continuous subbands can be generated in the spectrum if one tunes the dot potential and the dot-strand coupling appropriately. Typical cases with two and three strand Fibonacci ladders in the off diagonal mo...

  12. Bose metals and insulators on multileg ladders with ring exchange

    Science.gov (United States)

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

    2011-12-01

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

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

    OpenAIRE

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

    2011-01-01

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

  14. Fish Mouths

    Science.gov (United States)

    Twin Cities Public Television, Inc.

    2006-01-01

    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.

  15. 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 ...

  16. Fish forms

    Science.gov (United States)

    2012-06-26

    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.

  17. The phonon and thermal properties of a ladder nanostructure

    Directory of Open Access Journals (Sweden)

    M Mardaani

    2011-12-01

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

  18. Exact solutions and ladder operators for a new anharmonic oscillator

    International Nuclear Information System (INIS)

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

  19. Two-loop ladder diagram contributions to Bhabha scattering. III

    International Nuclear Information System (INIS)

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

  20. 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

  1. Action-angle variables, ladder operators and coherent states

    Science.gov (United States)

    Campoamor-Stursberg, R.; Gadella, M.; Kuru, ?.; Negro, J.

    2012-07-01

    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.

  2. Optical coherences and wavelength mismatch in ladder systems

    CERN Document Server

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

    2013-01-01

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

  3. A generalized spin ladder in a magnetic field

    CERN Document Server

    Frahm, H; Frahm, Holger; Rödenbeck, Claus

    1999-01-01

    We study the phase diagram of coupled spin-1/2 chains with bilinear and (chiral) three-spin exchange interactions in a magnetic field. The model is soluble on a one-parametric line in the space of coupling constants connecting the limiting cases of a single and two decoupled Heisenberg chains with nearest neighbour exchange only. We give a complete classification of the low-energy properties of the integrable system and introduce a numerical method which allows to study the possible phases of spin ladder systems away from the soluble line in a magnetic field.

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

    International Nuclear Information System (INIS)

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

  5. Azygos ladder and looped thoracic duct – a case report

    Directory of Open Access Journals (Sweden)

    Kumar N

    2011-04-01

    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.

  6. Molecular vibrational ladder climbing using a sub-nanosecond chirped laser pulse

    Science.gov (United States)

    Marcus, G.; Zigler, A.; Friedland, L.

    2006-04-01

    A comparison between the quantum ladder climbing and the classical autoresonance for robust molecular vibrational excitation from the ground state shows the disadvantage of shortening the exciting infrared laser pulse to the sub-picosecond range. Therefore, we demonstrated ladder climbing in HF molecule by a sub-nanosecond chirped laser pulse.

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

    Science.gov (United States)

    Ucak, C.

    2009-01-01

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

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

    Science.gov (United States)

    Campbell, Alan O; Pagano, Christopher C

    2014-06-01

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

  9. Fish Prints

    Science.gov (United States)

    California Academy of Sciences

    2008-01-01

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-08-15

    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.

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

    Science.gov (United States)

    Pal, Biplab; Chakrabarti, Arunava

    2014-06-01

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

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

    Science.gov (United States)

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

    2014-01-28

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

  13. A decision ladder analysis of eco-driving: the first step towards fuel-efficient driving behaviour.

    Science.gov (United States)

    McIlroy, Rich C; Stanton, Neville A

    2015-06-01

    This paper provides a decision ladder analysis of eco-driving, and a discussion of the resultant models in terms of the skills, rules and knowledge taxonomy of human behaviour and how this can inform the design of an in-vehicle, eco-driving support system. In order to understand the types of behaviours that characterise fuel-efficient driving, a review was conducted of the academic literature and of more publicly available resources, such as governmental, car manufacturers' and specific eco-driving organisations' websites. The review identified four largely distinct driving activities that play a central role in the use of fuel in the private road vehicle. A focus group involving four researchers in the transport ergonomics field, followed by a series of five interviews with eco-driving experts, served to validate, supplement and further specify the models. Practitioner Summary: This paper presents a decision ladder analysis of eco-driving. A four-member focus group and five interviews with eco-driving experts were conducted; the resultant models are discussed in terms of supporting fuel-efficient driving behaviours in the novice eco-driver through their potential to inform the design of an in-vehicle eco-driving support system. PMID:25604541

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

    OpenAIRE

    Barclay, Paula

    2013-01-01

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

  15. 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.

  16. Ladder-shaped polyether compound, desulfated yessotoxin, interacts with membrane-integral alpha-helix peptides.

    Science.gov (United States)

    Mori, Megumi; Oishi, Tohru; Matsuoka, Shigeru; Ujihara, Satoru; Matsumori, Nobuaki; Murata, Michio; Satake, Masayuki; Oshima, Yasukatsu; Matsushita, Nobuto; Aimoto, Saburo

    2005-09-01

    Ladder-shaped polyether compounds, represented by brevetoxins, ciguatoxins, maitotoxin, and prymnesins, are thought to possess the high affinity to transmembrane proteins. As a model compound of ladder-shaped polyethers, we adopted desulfated yessotoxin (2) and examined its interaction with glycopholin A, a membrane protein known to form a dimer or oligomer. Desulfated yessotoxin turned out to interact with the alpha-helix so as to induce the dissociation of glycopholin oligomers when examined by SDS and PFO gel electrophoresis. The results provided the first evidence that ladder-shaped polyethers interact with transmembrane helix domains. PMID:15990315

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

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Grunert, Suzanne C.

    1995-01-01

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

  18. Nested Bethe Ansatz for Spin Ladder Model with Open Boundary Conditions

    International Nuclear Information System (INIS)

    The nested Bethe ansatz (BA) method is applied to find the eigenvalues and the eigenvectors of the transfer matrix for spin-ladder model with open boundary conditions. Based on the reflection equation, we find the general diagonal solution, which determines the general boundary interaction in the Hamiltonian. We introduce the spin-ladder model with open boundary conditions. By finding the solution K± of the reflection equation which determines the nontrivial boundary terms in the Hamiltonian, we diagonalize the transfer matrix of the spin-ladder model with open boundary conditions in the framework of nested BA.

  19. Quasiparticle collapsing in an anisotropic t-J ladder

    Science.gov (United States)

    Zhu, Zheng; Weng, Zheng-Yu

    2015-03-01

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

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

    CERN Document Server

    Koganov, Gennady A

    2014-01-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

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

    DEFF Research Database (Denmark)

    Radder, Laetitia; Grunert, Klaus G.

    2009-01-01

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

  3. Topological phases of the two-leg Kitaev ladder

    International Nuclear Information System (INIS)

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

  4. Efficient population transfer in a ladder system by chirped pulses

    International Nuclear Information System (INIS)

    Enhanced population transfer from the lowest to the highest level in the three-state ladder 5s->5p->5d of the rubidium atom by frequency swept ultra short laser pulses is observed if the frequency sweep first makes the pulse resonant with the 5s->5p transition, and later with the 5p->5d transition. With this intuitive scheme it is possible to achieve complete population inversion via the intermediate level by two successive adiabatic passages. Complete inversion is also obtained by a open-quote counterintuitive close-quote direction of the frequency-sweep, in which case population of the intermediate level during the pulse is strongly reduced. The atomic system can be seen as a model system for multistep vibrational excitation in an anharmonic molecular potential

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

    CERN Document Server

    Lehman, L; Brennen, G K

    2012-01-01

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

  6. Benefits of fish passage and protection measures at hydroelectric projects

    International Nuclear Information System (INIS)

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

  7. Venomous Fish

    Science.gov (United States)

    Jonathan Bird Productions

    2010-08-10

    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.

  8. Texture Fish

    Science.gov (United States)

    Stone, Julie

    2007-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Edwin Mark Grandcourt

    2011-10-01

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

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

    Directory of Open Access Journals (Sweden)

    Mahmoud A. Barghash

    2011-01-01

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

  11. 36 CFR 2.3 - Fishing.

    Science.gov (United States)

    2010-07-01

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

  12. Power Test of the Ladder IH-RFQ Accelerator at Peking University

    International Nuclear Information System (INIS)

    A 104-MHz ladder interdigital-H radio frequency quadrupole accelerator (T-IH-RFQ) is developed for applying RFQs to heavy ion implantation and accelerator-based mass spectroscopy in recent years at the Institute of Heavy Ion Physics, Peking University. It could accelerate ions with a mass-to-charge ratio of less than 14, from 2.9 keV/u to 35.7 keV/u within a length of 1.1 m. The T-IH-RFQ cavity operating at H21(0) mode was constructed successfully. Based on a well designed rf power feeding system, the cavity was cold measured and tested with high rf power. In the case of cold measurement, the rf properties were obtained using a vector network analyzer with the help of a perturbation capacitor. During a high power test, the inter-electrode voltage was derived from the energy spectrum of x-rays measured by a high purity Ge detector. The results show that the specific shunt impedance of the T-IH-RFQ cavity reaches 178 k?m, which could meet the requirements of beam dynamics design. (nuclear physics)

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

    US Fish and Wildlife Service, Department of the Interior — This is a collection of memorandum and documents related to the installation of a closure structure at Holla Bend National Wildlife Refuge. The U.S. Fish and...

  14. Ab initio study of ladder-type polymers polythiophene and polypyrrole

    CERN Document Server

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

    2006-01-01

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

  15. Generalized ladder operators for the Dirac-Coulomb problem via SUSY QM

    International Nuclear Information System (INIS)

    The supersymmetry in quantum mechanics and shape invariance condition are applied as an algebraic method to solving the Dirac-Coulomb problem. The ground state and the excited states are investigated via new generalized ladder operators. (author)

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

    OpenAIRE

    Cotanch, Stephen R.; Maris, Pieter

    2003-01-01

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

  17. Opening of the Haldane Gap in Anisotropic Two- and Four-Leg Spin Ladders

    OpenAIRE

    Kim, Eugene H.; Solyom, J.

    1999-01-01

    We study the opening of the Haldane gap in two-leg and four-leg anisotropic spin ladders using bosonization and renormalization group methods, and we determine the phase diagram as a function of the interchain coupling and the relative anisotropy. It is found that the opening of the Haldane gap is qualitatively different for the two cases considered. For the two-leg ladder the Haldane gap opens for arbitrarily small interchain coupling, independent of the relative anisotropy...

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

    OpenAIRE

    Ayca Kangal

    2013-01-01

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

  19. Alternating-Spin Ladders in a Magnetic Field New Magnetization Plateaux

    CERN Document Server

    Langari, A

    2000-01-01

    We study numerically the formation of magnetization plateaux with the Lanczos method in 2-leg ladders with mixed spins of magnitudes $(S_1,S_2)=(1,1/2)$ located at alternating positions along the ladder and with dimerization $\\gamma$. For interchain coupling $J'>0$ and $\\gamma=0$, we find normalized plateaux at $m=1/3$ starting at zero field and $m=1$ (saturation), while when $\\gamma \

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

    OpenAIRE

    Marquette, Ian

    2010-01-01

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

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

    OpenAIRE

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

    2005-01-01

    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...

  2. Electronic Ladders with SO(5) Symmetry: Phase Diagrams and Correlations at half-filling

    OpenAIRE

    Frahm, Holger(Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany); Stahlsmeier, Martin

    2000-01-01

    We construct a family of electronic ladder models with SO(5) symmetry which have exact ground states in the form of finitely correlated wave functions. Extensions for these models preserving this symmetry are studied using these states in a variational approach. Within this approach, the zero temperature phase diagram of these electronic ladders at half filling is obtained, reproducing the known results in the weak coupling (band insulator) and strong coupling regime, first ...

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

    OpenAIRE

    Marcel Rešovský; Tomáš Bálint; Omer Faraj S. Amaitiek

    2010-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Marcel Rešovský

    2010-03-01

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

  5. Do Fish Enhance Tank Mixing?

    OpenAIRE

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

    2005-01-01

    The design of fish rearing tanks represents a critical stage in the development of optimal aquaculture systems, especially in the context of recirculating systems. Poor hydrodynamics can compromise water quality, waste management and the physiology and behaviour of fish, and thence, production potential and operational profitability. The hydrodynamic performance of tanks, therefore, represents an important parameter during the tank design process. Because there are significant complexities in...

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

    Science.gov (United States)

    White, Katherine; Timmons, Maryellen; Medders, Paul

    2011-01-01

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

  7. Fish oil

    Science.gov (United States)

    ... protect the blood vessel against closing down. Recurrent miscarriage in pregnant women with antiphospholipid syndrome. Taking fish oil seems to prevent miscarriage and increase live birth rate in pregnant women ...

  8. About Fish

    Science.gov (United States)

    David Ipsen

    2008-04-01

    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.

  9. D0 Silicon Upgrade: Thermal Analysis of the D0 Double Sided Ladders

    International Nuclear Information System (INIS)

    A side view of the double sided ladder is shown in Figure 1. There are two types of double sided ladder; 6 chip and 9 chip. The 6 chip ladder has three SVX II chips mounted directly opposite the cooling channel and 3 chips mounted at the ladder end. The 9 chip ladder has 4 SVX II chips directly opposite the cooling channel and 5 chips at the ladder end. The power density is highest in the 6 chip ladder. All plots and calculations in this Engineering Note pertain to the 6 chip ladder with the understanding that the 9 chip temperature profile is somewhat improved over the 6 chip due to the reduced power density in the row of chips opposite the cooling channel. The two dimensional finite difference technique used for these calculations is described in DOEN 447 and will not be described here. The assumed thermal conductivity of beryllium is 190 W/m-K, and that of silicon is 149 W/m-K. The SVX II power dissipation is assumed 0.400 W. There is no cable or hybrid component power dissipation in this set of simulations. The epoxy in the glue joints consists of 2 mils thickness of thermally conductive epoxy with 0.8 W/m-K conductivity and 1 mil thickness of 0.22 W/m-K unfilled epoxy. The assumed gas temperature outboard of the bulkhead is 15 C with a convection coefficient of 5 W/m2-K. The cooling channel temperature is 0 C. The intention of this series of simulations is to determine the optimum thickness to achieve an acceptable silicon temperature during operation able silicon temperature during operation of the ladder. Once the operating temperature profile is known, the temperatures within the beryllium substrates are used as input for an ANSYS* calculation of the bow of the ladder during operation. A series of calculations have been performed over the last several months in order to consider the effect of thickness, chip power, gas temperature, etc. on the temperature profile. Only the final plots are shown here in runs 660, 661, and 662. In these three plots the conditions are identical except for the beryllium substrate thickness which is 0.3/0.3, 0.4/0.4, and 0.5/0.3 bottom/top beryllium thicknesses, which are in dimensions of mm.

  10. Infrared Investigation of the Charge Ordering Pattern in the Organic Spin Ladder Candidate (DTTTF)2Cu(mnt)2

    OpenAIRE

    Musfeldt, J. L.; Brown, S.; Mazumdar, S; Clay, R. T.; Mas-Torent, M.; Rovira, C.; Dias, J C; Henriques, R. T.; Almeida, M

    2007-01-01

    We measured the variable temperature infrared response of the spin ladder candidate (DTTTF)2Cu(mnt)2 in order to distinguish between two competing ladder models, rectangular versus zigzag, proposed for this family of materials. The distortion along the stack direction below 235 K is consistent with a doubling along b through the metal-insulator transition. While this would agree with either of the ladder models, the concomitant transverse distortion rules out the rectangular...

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

    Directory of Open Access Journals (Sweden)

    Mostafa M. Gomaa

    2011-02-01

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

  12. 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)

    Knapp, Suzanne M.

    1995-01-01

    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).

  13. Louisiana ESI: FISH (Fish Polygons)

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

  14. Hawaii ESI: FISH (Fish Polygons)

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

  15. Electronic Properties of Fe-based Ladder Compounds

    Science.gov (United States)

    Du, Fei; Ohgushi, Kenya; Ueda, Yutaka

    2015-03-01

    The crystal structure of Fe-based superconductors found so far have two-dimensional conducting planes composed of a square lattice of Fe atoms coordinated tetrahedrally by pnictogens or chalcogens. Although there is no report on the discovery of superconductivity in Fe-based materials with one-dimensional structures, elucidating electronic states of such compounds is expected to give an important clue to the mechanism of superconductivity as well as a strong hint for searching new superconductors. We here report on electronic properties of a series of quasi-one-dimensional spin-ladder compounds AFe2X3 (A = K, Cs, Ba; X = S, Se) with a special focus on a solid-solution AFe2(S1-xSex)3 . We demonstrate that fruitful electronic states emerge as a consequence of the strong electron correlation effect and quantum fluctuations in a low dimensional crystal structure. The following is the list of papers directly related to this talk: [1] Y. Nambu, et al., Phys. Rev. B, 85 064413 (2012). [2] F. Du, et al, Phys. Rev. B 85, 214436 (2012). [3] F. Du, et al, Phys. Rev. B 90, 085143 (2014).

  16. Apollo 11 Astronaut Neil Armstrong Performs Ladder Practice

    Science.gov (United States)

    1969-01-01

    In preparation of the nation's first Lunar landing mission, Apollo 11 crew members underwent training activities to practice activities they would be performing during the mission. In this photograph, Neil Armstrong, donned in his space suit, practices getting back to the first rung of the ladder on the Lunar Module (LM). The Apollo 11 mission launched from the Kennedy Space Center (KSC) in Florida via the Marshall Space Flight Center (MSFC) developed Saturn V launch vehicle on July 16, 1969 and safely returned to Earth on July 24, 1969. Aboard the space craft were astronauts Neil A. Armstrong, commander; Michael Collins, Command Module (CM) pilot; and Edwin E. (Buzz) Aldrin Jr., Lunar Module (LM) pilot. The CM, 'Columbia', piloted by Collins, remained in a parking orbit around the Moon while the LM, 'Eagle'', carrying astronauts Armstrong and Aldrin, landed on the Moon. On July 20, 1969, Armstrong was the first human to ever stand on the lunar surface, followed by Aldrin. During 2½ hours of surface exploration, the crew collected 47 pounds of lunar surface material for analysis back on Earth. With the success of Apollo 11, the national objective to land men on the Moon and return them safely to Earth had been accomplished.

  17. 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)

  18. Cowlitz Falls fish passage

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  20. 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

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

    Science.gov (United States)

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

    2008-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Roux, G

    2007-07-15

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

  3. Molecular-based 2D S = 1/2 Heisenberg Antiferromagnetic Layers and Ladders

    Science.gov (United States)

    Landee, Christopher

    2014-03-01

    Low dimensional Quantum Heisenberg Antiferromagnets (QHAF) have long provided materials with which to examine the influence of dimensionality and exchange anisotropy on critical behavior of cooperative systems. Molecular-based QHAF have provided materials with low exchange strengths (~ 10 K), facilitating examination of the compounds up to the saturation fields using current facilities. This presentation will provide an overview of recent developments of two classes of molecular magnets: 2D QHAF and spin ladders. Recent specific heat studies of Cu(pz)2(ClO4)2 in fields up to 45 tesla have determined the (H,T) phase diagram for this quasi-2D QHAF; the results will be compared to the results of QMC simulations of the diagram as a function of the intralayer exchange J, the interlayer exchange J', and the XY-exchange anisotropy parameter. Developments in the study of spin ladders include the discovery of Luttinger liquid behavior for two molecular-based spin layers: the strong-rung ladder BPCB, (piperidinium)2CuBr4 and the strong-rail ladder DIMPY, (2,3-dimethypyridinium)2CuBr4. The properties of a new, isotropic spin ladder will be reported.

  4. Strong-coupling phases of frustrated bosons on a two-leg ladder with ring exchange

    Science.gov (United States)

    Sheng, D. N.; Motrunich, Olexei I.; Trebst, Simon; Gull, Emanuel; Fisher, Matthew P. A.

    2008-08-01

    Developing a theoretical framework to access the quantum phases of itinerant bosons or fermions in two dimensions that exhibit singular structure along surfaces in momentum space but have no quasiparticle description remains a central challenge in the field of strongly correlated physics. In this paper we propose that distinctive signatures of such two-dimensional (2D) strongly correlated phases will be manifest in quasi-one-dimensional “ N -leg ladder” systems. Characteristic of each parent 2D quantum liquid would be a precise pattern of one-dimensional (1D) gapless modes on the N -leg ladder. These signatures could be potentially exploited to approach the 2D phases from controlled numerical and analytical studies in quasi-one-dimension. As a first step we explore itinerant-boson models with a frustrating ring-exchange interaction on the two-leg ladder, searching for signatures of the recently proposed two-dimensional d -wave-correlated Bose liquid (DBL) phase. A combination of exact diagonalization, density-matrix renormalization-group, variational Monte Carlo, and bosonization analysis of a quasi-1D gauge theory provide compelling evidence for the existence of an unusual strong-coupling phase of bosons on the two-leg ladder, which can be understood as a descendant of the two-dimensional DBL. We suggest several generalizations to quantum spin and electron Hamiltonians on ladders, which could likewise reveal fingerprints of such 2D non-Fermi-liquid phases.

  5. Exotic gapless Bose metals and insulators on multi-leg ladders

    Science.gov (United States)

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

    2011-03-01

    We present recent work establishing compelling evidence for the existence of quasi-1D descendants of the d -wave Bose liquid (DBL), a novel 2D quantum phase of itinerant bosons first discussed in. In particular, we study a model of hard-core bosons moving on the N -leg ladder square lattice with frustrating four-site ring exchange. In this talk, we focus on two novel phases: an incompressible gapless Mott insulator on the 3-leg ladder and a compressible gapless Bose metal on the 4-leg ladder. The former is a fundamentally quasi-1D phase that is insulating along the ladder but has two 1D gapless modes and power law transverse density-density correlations at incommensurate wave vectors; extensions of this phase to full 2D will be discussed. The latter, on the other hand, is conducting along the ladder and has five 1D gapless modes, one more than the number of legs; this represents a significant step forward in establishing the existence of the DBL in two dimensions. In both cases, we can understand the nature of the phase using slave-particle-inspired variational wave functions consisting of a product of two distinct Slater determinants, the properties of which compare impressively well to a DMRG solution of the model Hamiltonian.

  6. A Review of Topography in Fish Culture in Nigria Part Three

    OpenAIRE

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

    2012-01-01

    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...

  7. Competing valence-bond states of spin-3/2 fermions on a strongly coupled ladder

    Science.gov (United States)

    Szirmai, E.; Nonne, H.

    2014-12-01

    We study the possible ground-state configurations of two strongly coupled chains of charge neutral spin-3/2 fermionic atoms interacting via short-range van der Waals interaction. The coupling between the two chains is realized by a relatively large hopping amplitude. Exploiting the fact that such a ladder configuration can be mapped to an effective one-band model, we analyze the emerging ground states of the system. We show that various spatially inhomogeneous states, valence-bond states, and plaquette states compete depending on the filling and the ratio of the interaction strengths in the singlet and quintet scattering channel. We find that a Luttinger liquid state is the ground state of the strongly coupled ladder in an extended region of the parameter space, and we also show that a topologically nontrivial charge Haldane state can emerge in the strongly coupled ladder at quarter and three-quarter fillings.

  8. Opening of the Haldane gap in anisotropic two- and four-leg spin ladders

    International Nuclear Information System (INIS)

    We study the opening of the Haldane gap in two-leg and four-leg anisotropic spin ladders using bosonization and renormalization group methods, and we determine the phase diagram as a function of the interchain coupling and relative anisotropy Jz/Jxy. It is found that the opening of the Haldane gap is qualitatively different for the two cases considered. For the two-leg ladder the Haldane gap opens for arbitrarily small interchain coupling, independent of Jz/Jxy, and the Haldane phase exists in a large region of parameter space. For the four-leg ladder the opening of the Haldane gap is strongly dependent on both the interchain coupling as well as Jz/Jxy, and the Haldane phase exists only in a narrow region about the isotropic antiferromagnet. (c) 1999 The American Physical Society

  9. Theoretical studies of bonding properties and vibrational spectra of chosen ladder-like silsesquioxane clusters

    Science.gov (United States)

    Szczypka, Wojciech; Jele?, Piotr; Kole?y?ski, Andrzej

    2014-10-01

    In this work the DFT calculations were carried out by means of Gaussian 09 program using B3LYP XC functional and 6-311G(d) basis set for chosen ladder-like silsesquioxane model clusters. Vibrational frequencies computations and infrared spectra were obtained subsequently for above mentioned structures. The results of topological analysis of total electron density obtained in SCF calculations (Quantum Theory of Atoms in Molecules approach) and structural analysis based on Bond Valence Method are presented in order to analyze length and ramification of ladder-like structures and various functional group influence. The calculated infrared spectra show that peak derived from vibrations of Si-O “chains” is shifting towards lower frequencies with increasing length of the ladder while at the same time, the overall strains (BVM) are diminishing.

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

    International Nuclear Information System (INIS)

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

  11. 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

  12. 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)

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

    CERN Document Server

    Nersesyan, A A

    2011-01-01

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

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

    CERN Document Server

    Fetzer, Amy V

    2009-01-01

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

  15. Spin rotational symmetry breaking by orbital current patterns in two-leg ladders.

    OpenAIRE

    Chudzinski, Piotr; Gabay, M.; Giamarchi, Thierry

    2010-01-01

    We investigate the physical consequences of orbital current patterns (OCP) in doped two-leg Cu-O Hubbard ladders. The internal symmetry of the pattern, in the case of the ladder structure, differs slightly from that suggested so far for cuprates. We focus on this OCP and look for measurable signatures of its existence. We compute the magnetic field produced by the OCP at each lattice site and estimate its value in view of a possible experimental detection. Using a renormalization-group (RG) a...

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

    Directory of Open Access Journals (Sweden)

    Majid Pakdel and Kazem Mazlumi

    2014-03-01

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

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

    OpenAIRE

    Tsuchiizu, M.; Furusaki, A.

    2002-01-01

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

  18. The Short Range RVB State of Even Spin Ladders A Recurrent Variational Approach

    CERN Document Server

    Sierra, G; Sierra, German; Martin-Delgado, Miguel A.

    1997-01-01

    Using a recursive method we construct dimer and nondimer variational ansatzs of the ground state for the two-legged ladder, and compute the number of dimer coverings, the energy density and the spin correlation functions. The number of dimer coverings are given by the Fibonacci numbers for the dimer-RVB state and their generalization for the nondimer ones. Our method relies on the recurrent relations satisfied by the overlaps of the states with different lengths, which can be solved using generating functions. The recurrent relation method is applicable to other short range systems. Based on our results we make a conjecture about the bond amplitudes of the 2-leg ladder.

  19. Controlling Luttinger liquid physics in spin ladders under a magnetic field

    OpenAIRE

    Klanjs?ek, M.; Mayaffre, H.; Berthier, C.; Horvatic?, M.; Chiari, B.; Piovesana, O.; Bouillot, Pierre; Kollath, Corinna; Orignac, E.; Citro, R.; Giamarchi, Thierry

    2008-01-01

    We present a 14N nuclear magnetic resonance study of a single crystal of CuBr4(C5H12N)2 (BPCB) consisting of weakly coupled spin-1/2 Heisenberg antiferromagnetic ladders. Treating ladders in the gapless phase as Luttinger liquids, we are able to fully account for (i) the magnetic field dependence of the nuclear spin-lattice relaxation rate T?11 at 250 mK and for (ii) the phase transition to a 3D ordered phase occurring below 110 mK due to weak interladder exchange coupling. BPCB is thus an ...

  20. Surprises on the Way from 1D to 2D Quantum Magnets: the Novel Ladder Materials

    OpenAIRE

    Dagotto, E.; Rice, T. M.

    1995-01-01

    One way of making the transition between the quasi-long range order in a chain of S=1/2 spins coupled antiferromagnetically and the true long range order that occurs in a plane, is by assembling chains to make ladders of increasing width. Surprisingly this crossover between one and two dimensions is not at all smooth. Ladders with an even number of legs have purely short range magnetic order and a finite energy gap to all magnetic excitations. Predictions of this novel groun...

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

    OpenAIRE

    Screen, TE; Thorne, JR; Denning, RG; Bucknall, DG; Anderson, HL

    2002-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-09-15

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

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

    International Nuclear Information System (INIS)

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

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

    Scientific Electronic Library Online (English)

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

    2005-07-01

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

  5. 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

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

    DEFF Research Database (Denmark)

    Heppell, Joël; Lorenzen, Niels

    1998-01-01

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

  7. Fish hemoglobins

    Scientific Electronic Library Online (English)

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

    2007-06-01

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

  8. Fish hemoglobins

    Directory of Open Access Journals (Sweden)

    P.C. de Souza

    2007-06-01

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

  9. 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

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

    US Fish and Wildlife Service, Department of the Interior — This supplement recommends that a closure structure be integrated into the Arkansas River Project to stabilize water levels in the Holla Bend Refuge Lake. The...

  11. Practicality of Intermittent Ladder-Level Programs for Health Professionals in the Middle East and Africa.

    Science.gov (United States)

    Karlsson, Britta; Turner, Solveig M.

    The potential usefulness of an intermittent ladder curriculum for educating health professionals in the Middle East and Africa was evaluated. Intermittent education would allow students to complete a lower educational qualification abroad and then enter the job market at home for some years before continuing with additional, higher education…

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

    CERN Document Server

    Feder, Elie

    2011-01-01

    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.

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

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Beckmann, Suzanne C.

    2001-01-01

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

  14. Jacob's ladders, $\\zeta$-factorization and infinite set of metamorphosis of a multiform

    OpenAIRE

    Moser, Jan

    2015-01-01

    In this paper we use Jacob's ladders together with fundamental Hardy-Littlewood formula (1921) to prove the so-called $\\zeta$-factorization formula on the critical line. Simultaneously, we obtain a set of control parameters of metamorphosis of a multiform connected with the Riemann-Siegel formula.

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

    International Nuclear Information System (INIS)

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

  16. Phase Diagram of the 2-Leg Heisenberg Ladder with Alternating Dimerization

    CERN Document Server

    Martín-Delgado, M A; Sierra, G

    1998-01-01

    Using the Lanczos method we determine the phase diagram of the 2-leg AF-Heisenberg ladder with alternating dimerization. It consists of a resonating valence bond phase and a dimer phase separated by a critical line. Our results are in good agreement with previous conjectures obtained with the non linear sigma model.

  17. Hydrokinetic turbine effects on fish swimming behaviour.

    Science.gov (United States)

    Hammar, Linus; Andersson, Sandra; Eggertsen, Linda; Haglund, Johan; Gullström, Martin; Ehnberg, Jimmy; Molander, Sverker

    2013-01-01

    Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms(-1). The effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish movements, particularly for large species, with possible effects on habitat connectivity if migration routes are exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of several metres width to allow large fish to pass through. In combination with further research the insights from this study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological impacts. PMID:24358334

  18. 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.

  19. Fish Tales

    Energy Technology Data Exchange (ETDEWEB)

    McLerran, L.

    2010-07-06

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

  20. Sport Fishing Regulations

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

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

    Scientific Electronic Library Online (English)

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

    2014-12-01

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

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

    OpenAIRE

    Kimura, Takashi; Kuroki, Kazuhiko; Aoki, Hideo

    1997-01-01

    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...

  3. Fishing amplifies forage fish population collapses.

    Science.gov (United States)

    Essington, Timothy E; Moriarty, Pamela E; Froehlich, Halley E; Hodgson, Emma E; Koehn, Laura E; Oken, Kiva L; Siple, Margaret C; Stawitz, Christine C

    2015-05-26

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches. PMID:25848018

  4. Fishing amplifies forage fish population collapses

    Science.gov (United States)

    Essington, Timothy E.; Moriarty, Pamela E.; Froehlich, Halley E.; Hodgson, Emma E.; Koehn, Laura E.; Oken, Kiva L.; Siple, Margaret C.; Stawitz, Christine C.

    2015-01-01

    Forage fish support the largest fisheries in the world but also play key roles in marine food webs by transferring energy from plankton to upper trophic-level predators, such as large fish, seabirds, and marine mammals. Fishing can, thereby, have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to dangerously low levels, where dependent predators are most vulnerable. However, disentangling the contributions of fishing vs. natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here, we overcome this difficulty by collating population time series for forage fish populations that account for nearly two-thirds of global catch of forage fish to identify the fingerprint of fisheries on their population dynamics. Forage fish population collapses shared a set of common and unique characteristics: high fishing pressure for several years before collapse, a sharp drop in natural population productivity, and a lagged response to reduce fishing pressure. Lagged response to natural productivity declines can sharply amplify the magnitude of naturally occurring population fluctuations. Finally, we show that the magnitude and frequency of collapses are greater than expected from natural productivity characteristics and therefore, likely attributed to fishing. The durations of collapses, however, were not different from those expected based on natural productivity shifts. A risk-based management scheme that reduces fishing when populations become scarce would protect forage fish and their predators from collapse with little effect on long-term average catches. PMID:25848018

  5. Intelligent Fish Freshness Assessment

    OpenAIRE

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

    2008-01-01

    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...

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

    OpenAIRE

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

    2011-01-01

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

  7. Plastic fish

    CERN Multimedia

    Antonella Del Rosso

    2015-01-01

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

  8. Can Fishing

    Science.gov (United States)

    Lawrence Hall of Science

    1981-01-01

    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).

  9. FWS Special Designation Areas

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

  10. Can north american fish passage tools work for South american migratory fishes?

    OpenAIRE

    Claudio Rafael Mariano Baigún; John Michael Nestler; Norberto Oscar Oldani; R. Andrew Goodwin; Larry J. Weber

    2007-01-01

    In North America, the Numerical Fish Surrogate (NFS) is used to design fish bypass systems for emigrating juvenile salmon as they migrate from hatchery outfalls and rearing habitats to adult habitat in the oceans. The NFS is constructed of three linked modules: 1) a computational fluid dynamics model describes the complex flow fields upstream of dams at a scale sufficiently resolved to analyze, understand and forecast fish movement, 2) a particle tracking model interpolates hydraulic informat...

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

    OpenAIRE

    Stacey, Natasha

    2007-01-01

    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...

  12. Traditional fishing tools

    OpenAIRE

    Stoica, Georgeta

    2009-01-01

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

  13. Meat, Poultry and Fish

    Science.gov (United States)

    Meat, Poultry and Fish Updated:May 4,2015 AHA Recommendation Choose fish, shellfish, poultry without the skin, and trimmed lean meats, no more ... at least 2 servings of baked or grilled fish each week, especially oily fish. Choose low-sodium, ...

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

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

    2012-01-01

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

  16. Low Energy Properties of Ferrimagnetic 2-leg Ladders a Lanczos study

    CERN Document Server

    Langari, A

    2001-01-01

    We apply the Lanczos method to a 2-leg ladder with mixed spins of magnitudes $(S_1,S_2)=(1,1/2)$ located at alternating positions along the ladder. The effect of dimerization $\\gamma$ is also considered according to two different patterns. A Spin Wave Theory (SWT) is applied to this model predicting one gapless branch with ferromagnetic properties and another gapful branch with antiferromagnetic nature as low energy excitations of the model. We compute the ground state energies, Ferro- and AF-excitation gaps, magnetizations and correlation functions as a function of $J'$ and $\\gamma$ which results into a fine estimate of the phase diagram. The Lanczos results are compared with the SWT analysis and a qualitative agreement is found but with numerical discrepancies. We also study numerically the Spin-Peierls instability and find that it is conditional for any value of $ J' \\in (0, 2)$ and both dimerization patterns.

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

    DEFF Research Database (Denmark)

    Grunert, Klaus G.; Bech-Larsen, Tino

    2005-01-01

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

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

    Science.gov (United States)

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

    2015-03-01

    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.

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

    CERN Document Server

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

    1996-01-01

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

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

    CERN Document Server

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

    1998-01-01

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

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

    CERN Document Server

    Azzouz, M; Moukouri, S; Liang Chen

    1994-01-01

    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.

  2. Is it a Fish?

    Science.gov (United States)

    OMSI

    2004-01-01

    This activity is on page 8 of the pdf, part of the Sea Life Discovery Box. This is an activity exploring the characteristics of fish. Learners are asked if they have seen a fish and what elements they saw that let them know it was a fish. A song about fish may be sung, engaging young learners. Pictures and a book about fish are viewed and important elements that fish have are noted: "tail fin," "dorsal fin," "pectoral fins," "pelvic fins." A clownfish puppet is shown and learners identify its fish characteristics.

  3. Mean-field theory for Heisenberg zigzag ladder: Ground state energy and spontaneous symmetry breaking

    OpenAIRE

    Mkhitaryan, V. V.; Sedrakyan, T. A.

    2006-01-01

    The spin-1/2 zig-zag Heisenberg ladder (J_1 - J_2 model) is considered. A new representation for the model is found and a saddle point approximation over the spin-liquid order parameter is performed. Corresponding effective action is derived and analytically analyzed. We observe the presence of phase transitions at values J_2/J_1=0.231 and J_2/J_1=1/2.

  4. Lattice Instability in the Spin-Ladder System under Magnetic Field

    OpenAIRE

    Nagaosa, Naoto; Murakami, Shuichi

    1998-01-01

    We study theoretically the lattice instability in the spin gap systems under magnetic field. With the magnetic field larger than a critical value h_{c1}, the spin gap is collapsed and the magnetization arises. We found that the lattice distortion occurs in the spin-ladder at an incommensurate wavevector corresponding to the magnetization, while it does not occur in the Haldane system. At low temperatures the magnetization curve shows a first order phase transition with this ...

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

    Science.gov (United States)

    Moreira, D. A.; Albuquerque, E. L.; Anselmo, D. H. A. L.

    2008-07-01

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

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

    International Nuclear Information System (INIS)

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

  7. Jacob's ladders, new properties of the function $\\arg\\zf$ and corresponding metamorphoses

    OpenAIRE

    Moser, Jan

    2015-01-01

    The notion of the Jacob's ladders, reversely iterated integrals and the $\\zeta$-factorization is used in this paper in order to obtain new results in study of the function $\\arg\\zf$. Namely, we obtain new formulae for non-local and non-linear interaction of the functions $|\\zf|$ and $\\arg\\zf$, and also a set of metamorphoses of the oscillating Q-system.

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

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, D.A. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil); Albuquerque, E.L. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)], E-mail: eudenilson@dfte.ufrn.br; Anselmo, D.H.A.L. [Departamento de Fisica, Universidade Federal do Rio Grande do Norte, 59072-970 Natal-RN (Brazil)

    2008-07-28

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

  9. Phase Diagram of a Spin Ladder with Cyclic Four Spin Exchange

    OpenAIRE

    Laeuchli, A.; Schmid, G.; Troyer, M.

    2002-01-01

    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 ...

  10. Ordered phases of XXZ-symmetric spin-1/2 zigzag ladder

    OpenAIRE

    Zarea, M.; Fabrizio, M.; Nersesyan, A. A.

    2003-01-01

    Using bosonization approach, we derive an effective low-energy theory for XXZ-symmetric spin-1/2 zigzag ladders and discuss its phase diagram by a variational approach. A spin nematic phase emerges in a wide part of the phase diagram, either critical or massive. Possible crossovers between the spontaneously dimerized and spin nematic phases are discussed, and the topological excitations in all phases identified.

  11. Quantum phases of attractive bosons on a Bose-Hubbard ladder with three-body constraint

    OpenAIRE

    Singh, Manpreet; Mishra, Tapan; Pai, Ramesh V.; Das, B. P.

    2014-01-01

    We obtain the complete quantum phase diagram of bosons on a two-leg ladder in the presence of attractive onsite and repulsive interchain nearest-neighbor interactions by imposing the onsite three-body constraint. We find three distinct phases; namely, the atomic superfluid (ASF), dimer superfluid (DSF), and the dimer rung insulator (DRI). In the absence of the interchain nearest-neighbor repulsion, the system exhibits a transition from the ASF to the DSF phase with increasin...

  12. Quantum Transport in Ladder-Type Networks: Role of nonlinearity, topology and spin

    OpenAIRE

    Nakamura, K.; Matrasulov, D.; Milibaeva, G.; Yusupov, J.; Salomov, U.; Ohta, T.; Miyamoto, M.

    2009-01-01

    We investigate quantum transport of electrons, phase solitons, etc. through mesoscopic networks of zero-dimensional quantum dots. Straight and circular ladders are chosen as networks with each coupled with three semi-infinite leads (with one incoming and the other two outgoing). Two transmission probabilities (TPs) as a function of the incident energy $\\epsilon$ show a transition from anti-phase aperiodic to degenerate periodic spectra at the critical energy $\\epsilon_c$ whi...

  13. Intellectual property rights in a quality-ladder model with persistent leadership

    OpenAIRE

    Kiedaisch, Christian

    2012-01-01

    This article analyzes the effects of intellectual property rights in a quality-ladder model in which incumbent firms preemptively innovate in order to keep their position of leadership. Unlike in models with leapfrogging, granting non-expiring forward protection reduces the rate of innovation and imposing a non-obviousness requirement reduces R&D spending. It is shown that full protection against imitation, granted independently of the size of the lead, maximizes the average innovation rate.

  14. The Short Range RVB State of Even Spin Ladders: A Recurrent Variational Approach

    OpenAIRE

    Sierra, German; Martin-Delgado, Miguel A.

    1997-01-01

    Using a recursive method we construct dimer and nondimer variational ansatzs of the ground state for the two-legged ladder, and compute the number of dimer coverings, the energy density and the spin correlation functions. The number of dimer coverings are given by the Fibonacci numbers for the dimer-RVB state and their generalization for the nondimer ones. Our method relies on the recurrent relations satisfied by the overlaps of the states with different lengths, which can b...

  15. Pair correlations of a spin-imbalanced Fermi gas on two-leg ladders

    OpenAIRE

    Feiguin, A. E.; Heidrich-meisner, F.

    2008-01-01

    We study the pair correlations of a spin-imbalanced two-leg ladder with attractive interactions, using the density matrix renormalization group method (DMRG). 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...

  16. Exciton dynamics in ladder-type methyl-poly(para-phenylene) doped with phosphorescent dyes

    International Nuclear Information System (INIS)

    The luminescence of a ladder-type methyl-poly(para-phenylene) (MeLPPP) doped with platinum-porphyrin dye PtOEP covering the concentration 10-3-5% by weight has been measured employing cw and transient techniques. Upon excitation into the range of absorption of the host, strong phosphorescence of the dopant is observed. Possible ways of populating the dopant triplet state are considered

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

    OpenAIRE

    Chen, Yang; Bai, Zhengyang; Huang, Guoxiang

    2014-01-01

    We propose a scheme to obtain stable nonlinear optical pulses and realize their storage and retrieval in an ultracold ladder-type three-level atomic gas via electromagnetically induced transparency. Based on Maxwell-Bloch equations we derive a nonlinear equation governing the evolution of probe field envelope, and show that optical solitons with ultraslow propagating velocity and extremely low generation power can be created in the system. Furthermore, we demonstrate that su...

  18. The phase diagram of magnetic ladders constructed from a composite-spin model

    OpenAIRE

    Legeza, Ors; Fath, Gabor; Solyom, Jeno

    1998-01-01

    White's density matrix renormalization group ({DMRG}) method has been applied to an $S= 1/2 + 1/2$ composite-spin model, which can also be considered as a two-leg ladder model. By appropriate choices of the coupling constants this model allows not only to study how the gap is opened around the gapless integrable models, but also to interpolate continuously between models with different spin lengths. We have found indications for the existence of several different massive pha...

  19. Telecast of Astronauts Armstrong and Aldrin by the Lunar Module ladder

    Science.gov (United States)

    1969-01-01

    Astronauts Neil A. Armstrong (on left), commander; and Edwin E. Aldrin Jr., lunar module pilot, are seen standing by the Lunar Module ladder in this black and white reproduction taken from a telecast by the Apollo 11 lunar surface television camera during the Apollo 11 extravehicular activity. This picture was made from a televised image received at the Deep Space Network tracking station at Goldstone, California.

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

    Science.gov (United States)

    1969-01-01

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

  1. 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)

  2. Three-ladder vertex in the Reggeon graph technique in QCD

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  4. Collapse of Fractal Structure in a Dynamic Fractional Stark Ladder Driven by an Intense THz Laser

    Science.gov (United States)

    Hino, Ken-Ichi; Ohno, Fumitaka; Nemoto, Yuya; Maeshima, Nobuya

    2014-03-01

    We examine a dynamic Wannier-Stark ladder in biased semiconductor superlattices driven by a monochromatic THz laser with a fractional matching ratio ? this is the ratio of a Bloch frequency to a laser frequency. This type of a dynamic Wanneir-Stark ladder is termed a dynamic fractional Stark ladder (DFSL). It is known that a DFSL shows fractal structure in quasienergy levels as a function of 1/ ? based on a tight-binding model. However, with the increase in intensity of an irradiated laser, it is found that photon-assisted tunneling causes single-channel shape-resonance with quasienergy shift and width, making inaccurate the above-mentioned fractal structure; the channel means a photon sideband of DFSL. In present study, we investigate the resonance structure of DFSL involving stronger interchannel interactions relevant to ac-Zener tunneling by applying a multichannel scattering based on the R-matrix Floquet theory. The obtained results show that conspicuous redshift of resonance spectral peaks and the associated resonance decay, concluding the collapse of the fractal structure characteristic of DFSL.

  5. Rotations of the most asymmetric molecules via 4-step and 1- step ladder operators

    Science.gov (United States)

    Ley-Koo, E.

    2015-04-01

    The symmetries of the free rotations of asymmetric molecules - at the levels of their respective Hamiltonians, spheroconal harmonic eigenfuntions, and eigenenergies - are reviewed in general. The situation of the most asymmetric molecules is analyzed in particular; their eigenstates with vanishing asymmetry-distribution eigenenergies are identified together with the Valdés and Piña 4-step ladder operators connecting them. Three sets of ladder operators identified by Méndez-Fragoso and Ley-Koo, connecting specific eigenstates of molecules with any symmetry, are also reviewed briefly. The successive applications of the 4- step ladder operators, to the lower eigenstates 1, y, xz, xyz, of the most asymmetric molecules, lead to their respective angular momentum ? = 4N, 4N+1, 4N+2, 4N+3, for N = 0,1,2..., companions of the same species with vanishing asymmetry-distribution energy; in turn, the successive application of the cartesian components of the angular momentum Lx, Ly, Lz operators to the above states, for each value of ?, lead to the respective companion states with the same angular momentum and companion species [xy, xz, yz,1], [z, xyz, x, y], [yz, 1, xy, xz], [x, y, z, xyz] and complementary excitations, thus completing each set of (2 ?+1) eigenstates, with symmetrically distributed energy levels.

  6. Chiral Mott insulators, Meissner effect, and Laughlin states in quantum ladders

    Science.gov (United States)

    Petrescu, Alexandru; Le Hur, Karyn

    2015-02-01

    We introduce generic bosonic models exemplifying that chiral Meissner currents can persist in insulating phases of matter. We first consider interacting bosons on a two-leg ladder. The total density sector can be gapped in a bosonic Mott insulator at odd-integer filling, while the relative density sector remains superfluid due to interchain hopping. Coupling the relative density to gauge fields yields a pseudospin Meissner effect. We show that the same phase arises if the bosons are replaced by spinful fermions confined in Cooper pairs, and find a dual fermionic Mott insulator with spinon currents. We prove that, by tuning the mean density, the Mott insulator with Meissner currents turns into a low-dimensional bosonic ? =1/2 Laughlin state for strong enough repulsive interactions across the ladder rungs. We finally discuss extensions to multileg ladders and bilayers in which spinon superfluids with Meissner currents become possible. We propose two experimental realizations, one with ultracold atoms in the setup of Atala et al. [Nat. Phys. 10, 588 (2014), 10.1038/nphys2998] and another with Josephson junction arrays. We also address a Bose-Fermi mixture subject to a magnetic field in connection with the pseudogap phase of high-Tc cuprates.

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

    International Nuclear Information System (INIS)

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

  8. 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

  9. d-wave correlated Bose liquid phases on multi-leg ladders with ring exchange

    Science.gov (United States)

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

    2010-03-01

    We discuss recent progress on the study of ladder descendants of a novel two-dimensional quantum phase of bosons moving on the square lattice which is characterized by singular surfaces in momentum space, namely the d-wave correlated Bose liquid (DBL). Using a combination of numerics (e.g., density matrix renormalization group, variational Monte Carlo, and exact diagonalization) and analytics (e.g., bosonization of a compact U(1) lattice gauge theory) we explore the existence and stability of ladder analogs of the DBL on N-leg ladders, with N>=3, in the context of a model of itinerant hard-core bosons with frustrating four-site ring exchange. As in the case of N=2, see [1], we find numerical evidence for various strong-coupling DBL phases which can rather remarkably be understood within a slave-fermion picture in which the boson wave function is written as a product of two Slater determinants. The additional features and difficulties associated with taking N>2 will be addressed. The boson ring model we consider has potential physical realizations in the contexts of low-dimensional frustrated quantum magnets and in ultracold quantum gases. [1] D. N. Sheng et al., Phys. Rev. B 78, 054520 (2008).

  10. Laboratory Studies on the Effects of Shear on Fish

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-09-20

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

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

    DEFF Research Database (Denmark)

    SØrensen, Elin; Grunert, Klaus G.

    1996-01-01

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

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

    CERN Document Server

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  14. 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

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

    OpenAIRE

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

    2011-01-01

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

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

    OpenAIRE

    Ketan Gajanan Nalawade; Ashish Sabu; Baskar P

    2014-01-01

    Automotive chassis is the back bone of an automobile, which acts as the frame to support the body and other different parts of the vehicle. It is the most crucial element that gives strength and stability to the vehicle under different conditions. So the frame should be extremely rigid and strong so that it can withstand shocks, twists, stresses and vibrations to which it is subjected while vehicle is moving on road. Thus strength and stiffness are the two important design considerations. In ...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Briand C.

    2012-01-01

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

  20. Salted fish and nasopharyngeal carcinoma in Malaysia.

    Science.gov (United States)

    Armstrong, R W; Eng, A C

    1983-01-01

    The evidence for a hypothesis that eating salted fish is associated with nasopharyngeal carcinoma (NPC) is reviewed. The hypothesis was tested among Malaysian Chinese using a matched case-control design. The kinds of salted fish and patterns of use were also investigated in a control group comprising 100 Chinese, 50 Malay and 50 Indian households. During 1980, in Selangor, Malaysia, interviews with 100 Chinese cases of NPC and 100 non-disease controls indicated that salted fish consumption during childhood was a significant risk (relative risk = 3.0, P = 0.04), with an elevated risk for daily as opposed to less frequent consumption. Salted fish consumption during adolescence was a less significant risk, and current consumption not at all. There were 19 kinds of fishes reported as being eaten as salted fish by the 200 control households. There were marked differences between ethnic groups in preference for different kinds: Chinese preferred red snapper (74% of households), Malay jewfish (54%) and Indian red snapper (28%). Salted fish was hardly ever eaten daily by any household; weekly was a moderate frequency in all ethnic groups; less than weekly most common. There were no statistically significant differences between Chinese NPC case and non-disease control participants in kind of salted fish eaten. Results were the same when the data were analyzed by sex, subethnic group and income. PMID:6635717

  1. Alaskan sport fishing waters

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

  2. SAMPLE FISH DATA, NC

    Science.gov (United States)

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

  3. Dynamic (Vibrational and Static Structural Analysis of Ladder Frame

    Directory of Open Access Journals (Sweden)

    Ketan Gajanan Nalawade

    2014-05-01

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

  4. Fish behaviour in relation to fishing operations

    OpenAIRE

    Fre?on, Pierre; Gerlotto, Franc?ois; Misund, O. A.

    1993-01-01

    The influence of fish behaviour on the most common stock assessment methods is reviewed. Fish behaviour may be divided into four major groups : habitat selection, aggregation pattern, avoidance reactions, and learning. Examples of temperate and tropical species are presented. (Résumé d'auteur)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1994-01-01

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

  6. Fish Family Identification

    Science.gov (United States)

    California Academy of Sciences

    2008-01-01

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

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

    OpenAIRE

    Southwell, Maura; Galassi, Maria; McRobert, Scott

    2012-01-01

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

  8. Got a Sick Fish?

    Science.gov (United States)

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

  9. Ciguatera Fish Poisoning

    OpenAIRE

    Falck, Troy M.; Suchard, Jeffrey R.

    2011-01-01

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

  10. Swimming and muscle structure in fish

    OpenAIRE

    Spierts, I.L.Y.

    1999-01-01

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

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

    Science.gov (United States)

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

    2015-03-01

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

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

    DEFF Research Database (Denmark)

    Olsen, SF; Østerdal, ML

    2007-01-01

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

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

    DEFF Research Database (Denmark)

    Olsen, Sjurdur Frodi; Østerdal, M L

    2007-01-01

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

  14. Predator Avoidance in Extremophile Fish

    OpenAIRE

    Martin Plath; Jeane Rimber Indy; Rüdiger Riesch; Claudia Zimmer; Lenin Arias-Rodriguez; Nina Herrmann; Matthias Schulte; David Bierbach

    2013-01-01

    Extreme habitats are often characterized by reduced predation pressures, thus representing refuges for the inhabiting species. The present study was designed to investigate predator avoidance of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in hydrogen sulfide-rich (sulfidic) springs or cave habitats, both of which are known to have impoverished piscine predator regimes. Focal fishes that inhabited sulfidic springs showed slightly weaker avoidance reactions...

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

    DEFF Research Database (Denmark)

    HØst, Jeppe Engset

    2012-01-01

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

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

    CERN Document Server

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

    2015-01-01

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

  17. Fragility of symmetry-protected topological order on a Hubbard ladder

    Science.gov (United States)

    Moudgalya, Sanjay; Pollmann, Frank

    2015-04-01

    Anfuso and Rosch [Phys. Rev. B 75, 144420 (2007), 10.1103/PhysRevB.75.144420] showed that the "topological" Haldane phase in a fermionic spin-1 /2 ladder can be continuously deformed into a "trivial" phase without explicitly breaking symmetries when local charge fluctuations are taken into account. Within the framework of symmetry-protected topological phases, we revisit the model and demonstrate how the Haldane phase can be adiabatically connected to a trivial phase due to charge fluctuations. Furthermore, we show that the Haldane phase remains stable as long as the system is symmetric under particular reflection symmetries.

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Qian, Jing; Zhang, Lu; Zhang, Weiping

    2015-01-01

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

  20. Luttinger liquid behaviour and superconducting correlations in t-J ladders

    CERN Document Server

    Hayward, C A; Sabatier, P C; Sabatier, Paul

    1995-01-01

    The low energy behaviour of the isotropic t--J ladder system is investigated using exact diagonalization techniques, specifically finding the Drude weight, the charge velocity and the compressibility. By applying the ideas of Luttinger liquid theory, we determine the correlation exponent K_\\rho which defines the behaviour of the long range correlations in the system. The boundary to phase separation is determined and a phase diagram is presented. At low electron density, a Tomonaga-Luttinger-like phase is stabilized whilst at higher electron densities a gapped phase with power law pairing correlations is stabilized: A large region of this gapped phase is found to exhibit dominant superconducting correlations.

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

    CERN Document Server

    Jones, D E; Pittman, T B

    2015-01-01

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

  2. Defect motion and lattice pinning barriers in Josephson-junction ladders

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-04-01

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

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

    OpenAIRE

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

    2014-01-01

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

  5. Bound states of magnons in the S=1/2 quantum spin ladder

    CERN Document Server

    Sushkov, O P

    1998-01-01

    We study the excitation spectrum of the two-leg antiferromagnetic S=1/2 Heisenberg ladder. Our approach is based on the description of the excitations as triplets above a strong-coupling singlet ground state. The quasiparticle spectrum is calculated by treating the excitations as a dilute Bose gas with infinite on-site repulsion. We find singlet (S=0) and triplet (S=1) two-particle bound states of the elementary triplets. We argue that bound states generally exist in any dimerized quantum spin model.

  6. Meissner to vortex phase transition in a two-leg ladder in artificial gauge field

    Science.gov (United States)

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

    2015-04-01

    We consider a two-leg boson ladder in artificial gauge field with hard-core intraleg and negligible interleg interactions. Using numerical simulations based on the Density Matrix Renormalization Group (DMRG) algorithm, combined with a bosonization approach, we study its commensurate-incommensurate transition to a vortex phase at a critical flux. We discuss the finite-size scaling behavior of the longitudinal current near the transition. For weak interchain boson hopping, the finite size scaling is in agreement with the predictions from bosonization.

  7. 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

  8. Indolocarbazole-based ligands for ladder-type four-coordinate boron complexes.

    Science.gov (United States)

    Curiel, David; Más-Montoya, Miriam; Usea, Laura; Espinosa, Arturo; Orenes, Raúl A; Molina, Pedro

    2012-07-01

    A novel class of ?-conjugated systems, which combine the indolo[3,2-b]carbazole unit with the formation of four-coordinate boron complexes, is presented. The resulting conjugated compounds have a double-laddered structure that provides interesting optical and electrochemical properties. The wide absorption range, covering most of the visible spectrum, along with the narrowing of the HOMO-LUMO energy gap, due to the presence of diphenylboryl centers, reinforces the potential of these molecules within the area of organic electronics. PMID:22716949

  9. Mott transition in a two-leg Bose-Hubbard ladder under an artificial magnetic field

    OpenAIRE

    Kele?, Ahmet; OKTEL, M. Ö.

    2014-01-01

    We consider the Bose-Hubbard model on a two-leg ladder under an artificial magnetic field, and investigate the superfluid-to-Mott insulator transition in this setting. Recently, this system has been experimentally realized [M.Atala \\textit{et al.}, Nature Physics \\textbf{10}, 588--593 (2014)], albeit in a parameter regime that is far from the Mott transition boundary. Depending on the strength of the magnetic field, the single-particle spectrum has either a single ground sta...

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

    International Nuclear Information System (INIS)

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

  11. Turbine related fish mortality

    International Nuclear Information System (INIS)

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

  12. Tropical Fish Rescue

    Science.gov (United States)

    Jonathan Bird Productions

    2010-02-01

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

  13. FISH PRODUCTION WORLDWIDE

    Directory of Open Access Journals (Sweden)

    Georgiana Melania COSTAICHE

    2014-12-01

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

  14. Fish allergy: in review.

    Science.gov (United States)

    Sharp, Michael F; Lopata, Andreas L

    2014-06-01

    Globally, the rising consumption of fish and its derivatives, due to its nutritional value and divergence of international cuisines, has led to an increase in reports of adverse reactions to fish. Reactions to fish are not only mediated by the immune system causing allergies, but are often caused by various toxins and parasites including ciguatera and Anisakis. Allergic reactions to fish can be serious and life threatening and children usually do not outgrow this type of food allergy. The route of exposure is not only restricted to ingestion but include manual handling and inhalation of cooking vapors in the domestic and occupational environment. Prevalence rates of self-reported fish allergy range from 0.2 to 2.29 % in the general population, but can reach up to 8 % among fish processing workers. Fish allergy seems to vary with geographical eating habits, type of fish processing, and fish species exposure. The major fish allergen characterized is parvalbumin in addition to several less well-known allergens. This contemporary review discusses interesting and new findings in the area of fish allergy including demographics, novel allergens identified, immunological mechanisms of sensitization, and innovative approaches in diagnosing and managing this life-long disease. PMID:23440653

  15. The Fishing Game

    Science.gov (United States)

    Bill Prothero

    The Fishing Game pits students against two virtual fishing companies. The goal is to maximize the company's bank account at the end of 10 years' fishing. This almost always results in a crash of the fishing population and ultimate demise of the fishing company. The player tries each of 4 resource management models in an attempt to both maximize profit and save the fisheries for the long term. A population modeling tool allows predictions to be made based on fishing effort and the management limitations. For example, fishing season length, % of marine reserves, or catch share, can be set depending on the chosen scenario. The results of game play are emailed to the instructor or can be printed out to hand in.

  16. Augmented fish health monitoring

    International Nuclear Information System (INIS)

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

  17. The Dimer-Hole-RVB State of the 2-Leg t-J Ladder A Recurrent Variational Ansatz

    CERN Document Server

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

    1997-01-01

    We present a variational treatment of the ground state of the 2-leg t-J ladder, which combines the dimer and the hard-core boson models into one effective model. This model allows us to study the local structure of the hole pairs as a function of doping. A second order recursion relation is used to generate the variational wave function, which substantially simplifies the computations. We obtain good agreement with numerical density matrix renormalization group results for the ground state energy in the strong coupling regime. We find that the local structure of the pairs depends upon whether the ladder is slightly or strongly dopped.

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

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

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

    CERN Document Server

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

    2014-01-01

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

  20. Elimination of Oil Residual inside the Copper Pipe Using Ladder Technique

    Directory of Open Access Journals (Sweden)

    Witsarut Sriratana

    2013-01-01

    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.

  1. Magnetic states of the two-leg-ladder alkali metal iron selenides AFe2Se3

    Science.gov (United States)

    Luo, Qinlong; Nicholson, Andrew; Rincón, Julián; Liang, Shuhua; Riera, José; Alvarez, Gonzalo; Wang, Limin; Ku, Wei; Samolyuk, German D.; Moreo, Adriana; Dagotto, Elbio

    2013-01-01

    Recent neutron scattering experiments addressing the magnetic state of the two-leg-ladder selenide compound BaFe2Se3 have unveiled a dominant spin arrangement involving ferromagnetically ordered 2×2 iron superblocks, that are antiferromagnetically coupled among them (the ``block-AFM''state). Using the electronic five-orbital Hubbard model first-principles techniques to calculate the electronic hopping amplitudes between irons, and the real-space Hartree-Fock approximation to handle the many-body effects, here it is shown that the exotic block-AFM state is indeed stable at realistic electronic densities close to n˜6.0. Another state with parallel spins along the rungs and antiparallel along the legs of the ladders (the “CX” state) is close in energy. This state becomes stable in other portions of the phase diagrams, such as with hole doping, as also found experimentally via neutron scattering applied to KFe2Se3. In addition, the present study unveils other competing magnetic phases that could be experimentally stabilized by varying either n chemically or the electronic bandwidth by pressure. Similar results were obtained using two-orbital models, studied here via Lanczos and density-matrix renormalization group (DMRG) techniques. A comparison of the results obtained with the realistic selenides hopping amplitudes for BaFe2Se3 against those found using the hopping amplitudes for pnictides reveals several qualitative similarities, particularly at intermediate and large Hubbard couplings.

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Basu, Anirban

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-12-15

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2015-06-01

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

  7. The Marijuana Ladder: measuring motivation to change marijuana use in incarcerated adolescents.

    Science.gov (United States)

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

    2006-06-01

    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 release. There was a significant negative relationship between ML scores and marijuana use and a significant positive relationship between ML scores and treatment engagement. When controlling for prior marijuana use and age, ML scores at baseline significantly added to the prediction of marijuana use and treatment engagement among incarcerated adolescents. Results support the concurrent validity and the predictive validity of the ML. This measure has the potential to provide important information for Juvenile Justice Facilities that might aid in treatment planning and discharge planning for incarcerated adolescents. In addition, researchers may find a quick visual analog measure of motivation to change marijuana use with good psychometric properties useful. PMID:16289930

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

    International Nuclear Information System (INIS)

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

  9. Ground-state and spectral properties of an asymmetric Hubbard ladder

    Science.gov (United States)

    Abdelwahab, Anas; Jeckelmann, Eric; Hohenadler, Martin

    2015-04-01

    We investigate a ladder system with two inequivalent legs, namely, a Hubbard chain and a one-dimensional electron gas. Analytical approximations, the density-matrix renormalization group method, and continuous-time quantum Monte Carlo simulations are used to determine ground-state properties, gaps, and spectral functions of this system at half-filling. Evidence for the existence of four different phases as a function of the Hubbard interaction and the rung hopping is presented. First, a Luttinger liquid exists at very weak interchain hopping. Second, a Kondo-Mott insulator with spin and charge gaps induced by an effective rung exchange coupling is found at moderate interchain hopping or strong Hubbard interaction. Third, a spin-gapped paramagnetic Mott insulator with incommensurate excitations and pairing of doped charges is observed at intermediate values of the rung hopping and the interaction. Fourth, the usual correlated band insulator is recovered for large rung hopping. We show that the wave numbers of the lowest single-particle excitations are different in each insulating phase. In particular, the three gapped phases exhibit markedly different spectral functions. We discuss the relevance of asymmetric two-leg ladder systems as models for atomic wires deposited on a substrate.

  10. Yakima Basin Fish Passage Project, Phase 2

    International Nuclear Information System (INIS)

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

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

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

  12. Columbia River ESI: FISH (Fish Polygons)

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

  13. Fat, fish, fish oil and cancer.

    OpenAIRE

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

    1996-01-01

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

  14. Physicochemical Process for Fish Processing Wastewater

    Directory of Open Access Journals (Sweden)

    NEENA SUNNY

    2013-04-01

    Full Text Available The main environmental problems of fish industries are high water consumption and high organic matter, oil and grease, ammonia and salt content in their wastewaters. The generated fish wastewater is rich in oil and grease, salt and ammonia. Biological treatments of such wastewater render them harmless. The primary causes of failure are a wide variety of inhibitory substances present in substantial concentrations in wastes. This paper consequently focuses on the inhibitors of biological treatment process for fish processing wastewater. It could be concluded from studies that system ammonia content, wastewater salinity, oil and grease play a decisive role in the efficiency of fish processing wastewater treatment. Physico-chemical was responsible for biological processes. An integrated design using physicochemical process followed by biological process would yield better treatment efficiency with less energy consumption and reduced sludge production.

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

    Directory of Open Access Journals (Sweden)

    Gregory Forth

    2012-06-01

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

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

    Science.gov (United States)

    Smyth, Russell; Mishra, Vinod; Qian, Xiaolei

    2010-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

    Matalová, Eva; Španová, A.

    2002-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2008-01-01

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

  19. Fish Breeding in Nigeria

    OpenAIRE

    J. A. Akankali; E.I. Seighabo; J. F.N. Abowei

    2011-01-01

    Fish breeding is a very important activity ensuring availability of fingerlings for the stocking of ponds, pens, tanks and cages. The breeding habits of fishes in nature differ from specie to specie Different species of fish choose different places in the aquatic environment for breeding. Most species do not breed when in captivity due to a number of factors. In Nigeria, induced breeding of African mud catfish through injection of ova prim hormone or pituitary gland is the main practice. This...

  20. Fish and wildlife surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Poston, T.M.

    1995-06-01

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

  1. Fish and wildlife surveillance

    International Nuclear Information System (INIS)

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

  2. Fishing in Europe

    Science.gov (United States)

    This interesting magazine from the European Commission covers diverse topics related to (but not exclusive of) the fishing industry (in .pdf format). The current issue of the magazine includes a piece from the Trade Union of Fish Merchants; the story of an expanding fishing village; the discovery of the Patagonian toothfish, a potentially threatened species; and a discussion of Total Allowable Catches for the year 2000.

  3. Fishing industry concerns

    International Nuclear Information System (INIS)

    The relationship between the oil and gas industry in the Irish Sea and its fishing industry is discussed in this paper. Liaison and effective communication between the two groups is essential to maintain a satisfactory working relationship. The fishing industry also supplies information to the Department of Trade and Industry on ecologically sensitive areas and types and methods of fishing, which is used when license applications are considered. (UK)

  4. Partial Replacement of Fish Meal with Spirulina pacifica in Diets for Parrot Fish (Oplegnathus fasciatus)

    OpenAIRE

    Kim, Sung-Sam; Rahimnejad, Samad; Kim, Kang-woong; Lee, Kyeong-Jun

    2013-01-01

    An 8-week feeding trial was conducted in low temperature season to investigate the effects of fish meal (FM) replacement with spirulina on growth performance, body composition and immune response of parrot fish and dietary antioxidant capacity. Four isonitrogenous (48% crud protein) and isocaloric (17.1 MJ/kg gross energy) diets were formulated to replace FM with 0 (as control), 5, 10 and 15% spirulina (designated as Con, S5, S10 and S15, respectively) and fed to the fish (initial body weight...

  5. Fish-allergic patients may be able to eat fish.

    Science.gov (United States)

    Mourad, Ahmad A; Bahna, Sami L

    2015-03-01

    Reported fish allergy prevalence varies widely, with an estimated prevalence of 0.2% in the general population. Sensitization to fish can occur by ingestion, skin contact or inhalation. The manifestations can be IgE or non-IgE mediated. Several fish allergens have been identified, with parvalbumins being the major allergen in various species. Allergenicity varies among fish species and is affected by processing or preparation methods. Adverse reactions after eating fish are often claimed to be 'allergy' but could be a reaction to hidden food allergen, fish parasite, fish toxins or histamine in spoiled fish. Identifying such causes would allow free consumption of fish. Correct diagnosis of fish allergy, including the specific species, might provide the patient with safe alternatives. Patients have been generally advised for strict universal avoidance of fish. However, testing with various fish species or preparations might identify one or more forms that can be tolerated. PMID:25666551

  6. Fish silage as feed ingredient for fish and livestock

    OpenAIRE

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

    2014-01-01

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

  7. Intelligent Fish Freshness Assessment

    Directory of Open Access Journals (Sweden)

    Deena Benjamin

    2008-04-01

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

  8. Anglers' fishing problem

    CERN Document Server

    Karpowicz, Anna

    2011-01-01

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

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

    OpenAIRE

    Suneth Jayampathi, R. P. S.

    2010-01-01

    The primary purpose of this study was to identify market segments based on personal values, values and lifestyles, environmental concern, fish welfare concern, ethical concern for fish farming and health involvement. A self-administrated questionnaire was conducted on a convenience sample of 209 Vietnamese consumers. It was designed to investigate consumers’ concern for issues used as segmentation basis together with variables used in profiling the segments. The measurement scales used in t...

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

    OpenAIRE

    Suneth Jayampathi, R. P. S.

    2010-01-01

    The primary purpose of this study was to identify market segments based on personal values, values and lifestyles, environmental concern, fish welfare concern, ethical concern for fish farming and health involvement. A self-administrated questionnaire was conducted on a convenience sample of 209 Vietnamese consumers. It was designed to investigate consumers’ concern for issues used as segmentation basis together with variables used in profiling the segments. The measurement scales used in t...

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

    Directory of Open Access Journals (Sweden)

    Gazalov V. S.

    2013-03-01

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

  12. Distance from a Fishing Community Explains Fish Abundance in a No-Take Zone with Weak Compliance

    Science.gov (United States)

    Alwany, Magdy A.; Bailey, David M.

    2015-01-01

    There are numerous examples of no-take marine reserves effectively conserving fish stocks within their boundaries. However, no-take reserves can be rendered ineffective and turned into ‘paper parks’ through poor compliance and weak enforcement of reserve regulations. Long-term monitoring is thus essential to assess the effectiveness of marine reserves in meeting conservation and management objectives. This study documents the present state of the 15-year old no-take zone (NTZ) of South El Ghargana within the Nabq Managed Resource Protected Area, South Sinai, Egyptian Red Sea. Previous studies credited willing compliance by the local fishing community for the increased abundances of targeted fish within the designated NTZ boundaries compared to adjacent fished or take-zones. We compared benthic habitat and fish abundance within the NTZ and the adjacent take sites open to fishing, but found no significant effect of the reserve. Instead, the strongest evidence was for a simple negative relationship between fishing pressure and distance from the closest fishing village. The abundance of targeted piscivorous fish increased significantly with increasing distance from the village, while herbivorous fish showed the opposite trend. This gradient was supported by a corresponding negative correlation between the amount of discarded fishing gear observed on the reef and increasing distance from the village. Discarded fishing gear within the NTZ suggested decreased compliance with the no-take regulations. Our findings indicate that due to non-compliance the no-take reserve is no longer functioning effectively, despite its apparent initial successes and instead a gradient of fishing pressure exists with distance from the nearest fishing community. PMID:25950815

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

    CERN Document Server

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

    2014-01-01

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

  14. Scaling of diffusion constants in the spin-1/2 XX ladder

    Science.gov (United States)

    Steinigeweg, R.; Heidrich-Meisner, F.; Gemmer, J.; Michielsen, K.; De Raedt, H.

    2014-09-01

    We study the dynamics of spin currents in the spin-1/2 XX ladder at finite temperature. Within linear response theory, we numerically calculate autocorrelation functions for quantum systems larger than what is accessible with exact diagonalization using the concept of dynamical quantum typicality. While the spin Drude weight vanishes exponentially quickly with increasing system size, we show that this model realizes standard diffusive dynamics. Moreover, we unveil the existence of three qualitatively different dependencies of the spin-diffusion coefficient on the rung-coupling strength, resulting from a crossover from exponential to Gaussian dissipation as the rung coupling increases, in agreement with analytical predictions. We further discuss the implications of our results for experiments with cold atomic gases.

  15. ROMANIA: CLIMBING THE LADDER FOR A BETTER FUTURE. WHEN WILL IT REACH EU AND EURO AREA?

    Directory of Open Access Journals (Sweden)

    Cristina Tatomir

    2011-12-01

    Full Text Available In this paper we assess the evolution of Romania’s economic convergence with the European Union (EU and Euro area, during the period 2000-2010. In order to determine the number of years required to reach the EU and Euro area average, we employ an economic convergence index, made up of real and structural convergence indexes. The analysis shows that Romania has been climbing the ladder in the process of catching-up with the EU and the Euro area until 2008 when, because of the international crisis, the economic convergence index started decreasing. We report that Romania will reach the EU average in April 2056 and the Euro area average in September 2062.As revealed by the analysis, it will take decadesto attain the European levels of economic convergence, this being the most important challenge for Romania on the long term.

  16. Phase Diagram of the Three Band Half-filled Cu-O Two-Leg Ladder

    CERN Document Server

    Lee, S; Fjaerestad, J O

    2005-01-01

    We determine the phase diagram of the half-filled two-leg ladder both at weak and strong coupling, taking into account the Cu d_{x^2-y^2} and the O p_x and p_y orbitals. At weak coupling, renormalization group flows are interpreted with the use of bosonization. Two different models with and without outer oxygen orbitals are examined. For physical parameters, and in the absence of the outer oxygen orbitals, the D-Mott phase arises; a dimerized phase appears when the outer oxygen atoms are included. We show that the circulating current phase that preserves translational symmetry does not appear at weak coupling. In the opposite strong-coupling limit the model is purely electrostatic and the ground states may be found by simple energy minimization. The phase diagram so obtained is compared to the weak-coupling results.

  17. Preparation and structural studies of black glasses based on ladder-like silsesquioxanes

    Science.gov (United States)

    Sitarz, M.; Jastrz?bski, W.; Jele?, P.; D?ugo?, E.; Gaw?da, M.

    2014-11-01

    Black glasses are very interesting and promising materials from the point of their thermal and mechanical resistance. They can be used as protective layers on different kind of substrates, like steel, titanium, glasses. Controlling amount of carbon introduced to its structure is crucial for the properties of the material. Samples were prepared by sol-gel method using ladder-like silsesquioxanes as precursor and were heat-treated at 800 °C in inert atmosphere. Middle infrared, EDX and MAS NMR studies were carried out on heated samples to determine their structure. All methods confirmed presence of Si-C bonds in the resulting material. Theoretical MIR spectrum, of the constructed black glass model, allowed to make a precise assignment of bands in the experimental spectrum.

  18. Vortex and Meissner phases of strongly interacting bosons on a two-leg ladder

    Science.gov (United States)

    Piraud, M.; Heidrich-Meisner, F.; McCulloch, I. P.; Greschner, S.; Vekua, T.; Schollwöck, U.

    2015-04-01

    We establish the phase diagram of the strongly interacting Bose-Hubbard model defined on a two-leg ladder geometry in the presence of a homogeneous flux. Our work is motivated by a recent experiment [M. Atala et al., Nat. Phys. 10, 588 (2014), 10.1038/nphys2998], which studied the same system, in the complementary regime of weak interactions. Based on extensive density matrix renormalization group simulations and a bosonization analysis, we fully explore the parameter space spanned by filling, interleg tunneling, and flux. As a main result, we demonstrate the existence of gapless and gapped Meissner and vortex phases, with the gapped states emerging in Mott-insulating regimes. We calculate experimentally accessible observables such as chiral currents and vortex patterns.

  19. Multidimensional spectroscopy with entangled light: loop vs ladder delay scanning protocols

    International Nuclear Information System (INIS)

    Multidimensional optical signals are commonly recorded by varying the delays between time ordered pulses. These control the evolution of the density matrix and are described by ladder diagrams. We propose a new non-time-ordered protocol based on following the time evolution of the wavefunction and described by loop diagrams. The time variables in this protocol allow one to observe different types of resonances and reveal information about intraband dephasing not readily available by time ordered techniques. The time variables involved in this protocol become coupled when using entangled light, which provides high selectivity and background free measurement of the various resonances. Entangled light can resolve certain states even when strong background due to fast dephasing suppresses the resonant features when probed by classical light. (paper)

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

    Science.gov (United States)

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

    2011-10-01

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

  1. Effects of goal difficulty and temporality in motor skill acquisition using the Bachman ladder.

    Science.gov (United States)

    Corrêa, Umberto Cesar; de Souza, Orlando Pereira Júnior

    2009-12-01

    The effects of different types of goal setting on motor skill learning were investigated. 100 individuals (64 men, 36 women) without experience in the performance of the Bachman ladder task participated. Participants were randomly assigned to one of five goal groups: (a) generic, (b) long-term, difficult, (c) long-term, easy, (d) short- and long-term, difficult, and (e) short- and long-term, easy. In the acquisition phase, participants performed 200 trials, and in the transfer and retention phases, each performed 50 trials. The dependent variable was the number of steps achieved in blocks of 10 trials. The results showed that the groups had similar performances in both the transfer and retention phases. Setting of generic, difficult, easy, long- and short-term, and self-setting goals all enabled similar effects on motor learning. PMID:20178281

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-10-31

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

  3. Two-leg SU (2 n ) spin ladder: A low-energy effective field theory approach

    Science.gov (United States)

    Lecheminant, P.; Tsvelik, A. M.

    2015-05-01

    We present a field-theory analysis of a model of two SU (2 n ) -invariant magnetic chains coupled by a generic interaction preserving time-reversal and inversion symmetry. Contrary to the SU(2)-invariant case the zero-temperature phase diagram of such two-leg spin ladder does not contain topological phases. Only generalized valence bond solid phases are stabilized when n >1 with different wave vectors and ground-state degeneracies. In particular, we find a phase which is made of a cluster of 2 n spins put in an SU (2 n ) singlet state. For n =3 , this cluster phase is relevant to 173Yb ultracold atoms, with an emergent SU(6) symmetry, loaded in a double-well optical lattice.

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

    International Nuclear Information System (INIS)

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

  5. Ladder approximation for three- and four-particle correlation functions: Application to thermodynamic perturbation theory

    International Nuclear Information System (INIS)

    We apply the recently developed ladder approximation for three- and four-particle correlation functions to thermodynamic perturbation theory. We calculate the first correction in the perturbative expansion of the pair correlation function and the second correction in the expansion of the free energy of a fluid of particles interacting via a hard-sphere reference potential plus a perturbing term. Both calculated quantities depend on the three- and four-particle correlation functions of the reference system. The results for the free energy are in good overall agreement with computer-simulation data over a wide range of densities, up to the hard-sphere fluid-solid phase transition. The results for the pair correlation function are in good agreement with computer-simulation data except near contact at high densities

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

    CERN Document Server

    Bharti, Vineet

    2015-01-01

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

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

    Science.gov (United States)

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

    2014-09-01

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

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

    CERN Document Server

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

    2006-01-01

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

  9. Anisotropic Superexchange for nearest and next nearest coppers in chain, ladder and lamellar cuprates

    CERN Document Server

    Tornow, S; Aharony, A

    1999-01-01

    We present a detailed calculation of the magnetic couplings between nearest-neighbor and next-nearest-neighbor coppers in the edge-sharing geometry, ubiquitous in many cuprates. In this geometry, the interaction between nearest neighbor coppers is mediated via two oxygens, and the Cu-O-Cu angle is close to 90 degrees. The derivation is based on a perturbation expansion of a general Hubbard Hamiltonian, and produces numerical estimates for the various magnetic energies. In particular we find the dependence of the anisotropy energies on the angular deviation away from the 90 degrees geometry of the Cu-O-Cu bonds. Our results are required for the correct analysis of the magnetic structure of various chain, ladder and lamellar cuprates.

  10. Coherence generation and population transfer in a three-level ladder system

    International Nuclear Information System (INIS)

    This work explores the effect of spontaneous emission on coherence generation and population transfer in a three-level ladder atomic system driven by two pulses in counterintuitive order. With adiabatic evolution and the weak-dephasing approximation, we find that a large coherence and population transfer can be achieved even with spontaneous decay rate. The maximum coherence and population transfer decrease with the increase of spontaneous decay rate from the highest state to intermediate state. But this effect can be compensated by shortening the pulse width and enlarging the delay time. Results show that the coherence generation and population transfer never depend on the spontaneous decay rate from the intermediate state to ground state. The validity of the analytic solution is examined by numerical calculation. (general)

  11. Thermodynamics of the S=1 spin ladder as a composite S=2 chain model

    CERN Document Server

    Rojas, O; De Souza, S M; Thomaz, M T; Rojas, Onofre

    2005-01-01

    A special class of S=1 spin ladder hamiltonians, with second- neighbor exchange interactions and with anisotropies in the $z$-direction, can be mapped onto one-dimensional composite S=2 (tetrahedral S=1) models. We calculate the high temperature expansion of the Helmoltz free energy for the latter class of models, and show that their magnetization behaves closely to that of standard XXZ models with a suitable effective spin $S_{eff}$, such that $S_{eff}(1+S_{eff})=$, where ${\\bf S}_i$ refers to the components of spin in the composite model. It is also shown that the specific heat per site of the composite model, on the other hand, can be very different from that of the effective spin model, depending on the parameters of the hamiltonian.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-15

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Oleg Pankratz

    2014-01-01

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

  15. Spinor Bethe--Salpeter equation with generaLized ladder kernels and the Goldstein problem

    International Nuclear Information System (INIS)

    The spinor Bethe--Salpeter equation is investigated for tightly bound fermion pairs. The covariant interaction kernel contains contributions of vector and axial-vector gluons within the framework of the Stueckelberg formalism. The free gluon propagators of the strict ladder approximation are replaced by a convenient spectral form. This generalized ladder model can be extended to a large class of gauge field theories by specifying the spectral functions. The model-independent O(4) analysis of the Wick-rotated wave functions is carried out by using a complete set of four-dimensional scalar, vector, and tensor spherical harmonics. At vanishing center-of-mass energy, the radial Bethe--Salpeter equation can be classified in six disconnected sectors. All these equations are recorded in a general form which provides a study of the gauge dependence of the wave functions at short distances. Illustrative calculations are based on a simple Abelian field theory. In two Goldstein equations the leading singular term of the kernel may be absent by cancellation. In addition, one obtains a generalized Goldstein equation in which the kernel includes a gauge-independent marginally singular term. It is discussed how corrections of the large-distance behavior of the singular Goldstein kernel can lead to normalizable bound-state solutions without introducing a short-distance cutoff. Exact and numerical solutions are presented by using a simple parametrization of the kernel. In other sectormetrization of the kernel. In other sectors, the noncanonical angular behavior of the solutions may be avoided by prescribing a complex mass for the Stueckelberg ghosts

  16. Fishing penetration injuries

    OpenAIRE

    Dudkiewicz, I.; Salai, M.; Blankstein, A.; Chechik, A.

    2000-01-01

    Background—Fishing involves millions of people throughout the world and is considered a pleasant and harmless sport. However, many kinds of injury can occur. Penetrating injuries to the extremities by fishing equipment such as hooks and harpoons, and even by scales, or infection from penetration of scales etc are relatively common although hardly ever reported in the literature.

  17. Folkbiology of Freshwater Fish

    Science.gov (United States)

    Medin, Douglas L.; Ross, Norbert O.; Atran, Scott; Cox, Douglas; Coley, John; Proffitt, Julia B.; Blok, Sergey

    2006-01-01

    Cross-cultural comparisons of categorization often confound cultural factors with expertise. This paper reports four experiments on the conceptual behavior of Native American and majority-culture fish experts. The two groups live in the same general area and engage in essentially the same set of fishing-related behaviors. Nonetheless, cultural…

  18. Explore it! Fish

    Science.gov (United States)

    Species profiles of 10 common, and often less-publicized, Great Lakes fishes. Each profile describes the fish's length, weight, coloring, common names, and preferred habitat. Site also discusses its creator, Cliff Kraft, and why he selected these 10 particular species. Profiles include: the lake sturgeon, lake herring, brook stickleback, brook trout, longnose sucker, deepwater sculpin, spottail shiner, siscowet, logperch, and lean lake trout.

  19. Build-a-Fish

    Science.gov (United States)

    2007-08-09

    In this interactive activity from Shedd Aquarium, build a fish and then release it into the reef to search for food and evade predators. Try different combinations and observe how each kind of fish has unique adaptations that help it survive in its habitat.

  20. Effects of radiations on ornamental fish

    International Nuclear Information System (INIS)

    Radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiations: ionizing and non-ionizing. Ultraviolet, X-rays, and gamma rays are some examples of radiation. 'Ornamental fish' is designed for aquatic hobbyists and the aquatic industry for several purposes. UV light has two primary uses in fish culture: Controlling green water and disinfecting the water supply. Many proponents of UV disinfection sometimes overlook the additional benefits relating to ornamental fish; those being that cleaner water reduces the stress on the fish by not having to fight off diseases, thus enhancing its immune system and leading to faster growth and more brilliant colors. Ultraviolet sterilizers are often used in aquaria to help control unwanted microorganisms in the water. UV radiation also ensures that exposed pathogens cannot reproduce, thus decreasing the likelihood of a disease outbreak in an aquarium. Despite of these benefits, the ill-effects of radiations cannot be ruled out. Ultraviolet Radiation-induced DNA Damage is seen in the skin of the Platyfish Xiphophorus. Higher radiation doses may cause the gastrointestinal syndrome that leads to defects of the intestinal mucosa barrier with successive contamination of musculature. Exposure to UV radiation can kill the fish and induce sublethal effects in embryos, larvae and adults. The change in skin includes irregularity of skin surface, epidermal oederegularity of skin surface, epidermal oedema, necrosis etc. Irradiation may badly influence the textural attributes of fish muscle. (author)

  1. Cooperative Search and Rescue with Artificial Fishes Based on Fish-Swarm Algorithm for Underwater Wireless Sensor Networks

    OpenAIRE

    Wei Zhao; Zhenmin Tang; Yuwang Yang; Lei Wang; Shaohua Lan

    2014-01-01

    This paper presents a searching control approach for cooperating mobile sensor networks. We use a density function to represent the frequency of distress signals issued by victims. The mobile nodes' moving in mission space is similar to the behaviors of fish-swarm in water. So, we take the mobile node as artificial fish node and define its operations by a probabilistic model over a limited range. A fish-swarm based algorithm is designed requiring local information at each fish node and maximi...

  2. Plasma Phospholipid Omega-3 Fatty Acids and Freshwater Fish Consumption in the Brazilian Amazon

    Directory of Open Access Journals (Sweden)

    Melanie Lemire

    2013-08-01

    Full Text Available Background: Amazonian riverside communities consume large quantities of freshwater fish, comparable to marine fish consumption of Inuit, Scandinavian and Japanese populations. Few studies have considered the relation of high freshwater fish consumption and intake of omega-3 fatty acids (FA. Objective: The objective of the present study was to determine the profile of the concentrations of plasma phospholipid FAs and its relation with freshwater fish intake in 12 riverside communities in the Tapajós River basin (State of Pará, Brazilian Amazon. Design: This cross-sectional study included 333 adults (15 - 86 years old. Fish meal frequency was determined using a 7-day interview-administered dietary recall questionnaire. Fish were categorized as piscivorous and non-piscivorous fish on trophic level. Plasma phospholipid FAs were measured by capillary gas-liquid chromatography. Results: Participants consumed 5 to 6 fish meals a week, with twice as many non-piscivorous fish than piscivorous fish (4.4 fish/week vs 2.2 fish/week, respectively. The omega-3 FA levels in plasma phospholipids were low (EPA + DHA = 31.21 mg/L; %EPA + DHA = 2.59%. Omega-3 FAs increased with frequency of fish intake, and particularly with piscivorous fish, controlling for sociodemographic, anthropometric and lifestyle characteristics. DHA levels were greater in women than in men. Conclusions: Omega-3 FA in this Amazonian population increased with fish consumption, but although they consumed freshwater fish almost daily, the concentrations of omega-3 FA were relatively low and comparable to fish-eater communities for which fish is not a dietary mainstay. It is possible that nutrients present in marine, but not in certain freshwater fish species, may facilitate absorption of omega-3 FA. Sex and/or gender differences must be taken into account when assessing the relationship between fish consumption and plasma phospholipid omega-3 FA levels.  

  3. COOL Biology Projects : gone Fishing

    Science.gov (United States)

    2007-12-12

    The Coastal Ocean Observatory Laboratory (COOL) of Rutgers Marine and Coastal Sciences invites teachers and students to use the COOL Classroom, a series of Internet-based instructional modules that link middle and high school classrooms with active research investigations conducted by Rutgers scientists. In the Gone Fishing module, students explore the role of phytoplankton in the marine food web, and learn a lot about the experimental design in the process. A printable teacher's guide helps educators capitalize on students' natural fascination with the marine environment to improve basic skills training, problem solving, and critical thinking skills.

  4. Modeling Fish Growth in Low Dissolved Oxygen

    Science.gov (United States)

    Neilan, Rachael Miller

    2013-01-01

    This article describes a computational project designed for undergraduate students as an introduction to mathematical modeling. Students use an ordinary differential equation to describe fish weight and assume the instantaneous growth rate depends on the concentration of dissolved oxygen. Published laboratory experiments suggest that continuous…

  5. Which Fish Should I Eat? Perspectives Influencing Fish Consumption Choices

    OpenAIRE

    KARAGAS, MARGARET R.; Mariën, Koenraad; Rheinberger, Christoph M.; Schoeny, Rita; Oken, Emily; Choi, Anna Lai; Korrick, Susan Abigail; Sunderland, Elsie

    2012-01-01

    Background: Diverse perspectives have influenced fish consumption choices. Objectives: We summarized the issue of fish consumption choice from toxicological, nutritional, ecological, and economic points of view; identified areas of overlap and disagreement among these viewpoints; and reviewed effects of previous fish consumption advisories. Methods: We reviewed published scientific literature, public health guidelines, and advisories related to fish consumption, focusing on advisories targete...

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

    CERN Document Server

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

    2000-01-01

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

  7. 76 FR 28799 - Commercial Fishing Safety Advisory Committee; Vacancies

    Science.gov (United States)

    2011-05-18

    ...matters relating to the safe operation of commercial fishing industry vessels. DATES: Applicants should submit a cover letter and resume in time to reach the Designated Federal Officer on or before June 30, 2011. ADDRESSES: Send your...

  8. SAMS #1: Using Fish Tissue Data to Monitor Remedy Effectiveness

    Science.gov (United States)

    This document provides general background and specific recommendations on how to design and implement fish monitoring programs for Superfund sites for the detection of significant changes in chemical residues....

  9. Why do fish school?

    Directory of Open Access Journals (Sweden)

    Matz LARSSON

    2012-02-01

    Full Text Available Synchronized movements (schooling emit complex and overlapping sound and pressure curves that might confuse the inner ear and lateral line organ (LLO of a predator. Moreover, prey-fish moving close to each other may blur the electro-sensory perception of predators. The aim of this review is to explore mechanisms associated with synchronous swimming that may have contributed to increased adaptation and as a consequence may have influenced the evolution of schooling. The evolutionary development of the inner ear and the LLO increased the capacity to detect potential prey, possibly leading to an increased potential for cannibalism in the shoal, but also helped small fish to avoid joining larger fish, resulting in size homogeneity and, accordingly, an increased capacity for moving in synchrony. Water-movements and incidental sound produced as by-product of locomotion (ISOL may provide fish with potentially useful information during swimming, such as neighbour body-size, speed, and location. When many fish move close to one another ISOL will be energetic and complex. Quiet intervals will be few. Fish moving in synchrony will have the capacity to discontinue movements simultaneously, providing relatively quiet intervals to allow the reception of potentially critical environmental signals. Besides, synchronized movements may facilitate auditory grouping of ISOL. Turning preference bias, well-functioning sense organs, good health, and skillful motor performance might be important to achieving an appropriate distance to school neighbors and aid the individual fish in reducing time spent in the comparatively less safe school periphery. Turning preferences in ancestral fish shoals might have helped fish to maintain groups and stay in formation, reinforcing aforementioned predator confusion mechanisms, which possibly played a role in the lateralization of the vertebrate brain [Current Zoology 58 (1: 116–128, 2012].

  10. Ageing of Fish

    OpenAIRE

    Institute, Marine

    2006-01-01

    In order to assess the state of any fish stock it is vital that the age structure of that stock is known. The age profile of a stock gives an indication on how healthy the stock is. If there is a broad range of ages present, then the stock would appear to be in good shape. If there are no young fish, then recruitment (spawning) may have failed and there will be problems in the future. If there are no old fish in the stock, then there may be overfishing of the stock. Age data give a good insig...

  11. Histamine fish poisoning revisited.

    Science.gov (United States)

    Lehane, L; Olley, J

    2000-06-30

    Histamine (or scombroid) fish poisoning (HFP) is reviewed in a risk-assessment framework in an attempt to arrive at an informed characterisation of risk. Histamine is the main toxin involved in HFP, but the disease is not uncomplicated histamine poisoning. Although it is generally associated with high levels of histamine (> or =50 mg/100 g) in bacterially contaminated fish of particular species, the pathogenesis of HFP has not been clearly elucidated. Various hypotheses have been put forward to explain why histamine consumed in spoiled fish is more toxic than pure histamine taken orally, but none has proved totally satisfactory. Urocanic acid, like histamine, an imidazole compound derived from histidine in spoiling fish, may be the "missing factor" in HFP. cis-Urocanic acid has recently been recognised as a mast cell degranulator, and endogenous histamine from mast cell degranulation may augment the exogenous histamine consumed in spoiled fish. HFP is a mild disease, but is important in relation to food safety and international trade. Consumers are becoming more demanding, and litigation following food poisoning incidents is becoming more common. Producers, distributors and restaurants are increasingly held liable for the quality of the products they handle and sell. Many countries have set guidelines for maximum permitted levels of histamine in fish. However, histamine concentrations within a spoiled fish are extremely variable, as is the threshold toxic dose. Until the identity, levels and potency of possible potentiators and/or mast-cell-degranulating factors are elucidated, it is difficult to establish regulatory limits for histamine in foods on the basis of potential health hazard. Histidine decarboxylating bacteria produce histamine from free histidine in spoiling fish. Although some are present in the normal microbial flora of live fish, most seem to be derived from post-catching contamination on board fishing vessels, at the processing plant or in the distribution system, or in restaurants or homes. The key to keeping bacterial numbers and histamine levels low is the rapid cooling of fish after catching and the maintenance of adequate refrigeration during handling and storage. Despite the huge expansion in trade in recent years, great progress has been made in ensuring the quality and safety of fish products. This is largely the result of the introduction of international standards of food hygiene and the application of risk analysis and hazard analysis and critical control point (HACCP) principles. PMID:10898459

  12. Response of potential fish community indicators to fishing

    OpenAIRE

    Piet, G. J.; Jennings, S.

    2005-01-01

    Fish community metrics and diversity indices have often been proposed as indicators to support an Ecosystem Approach to Fisheries Management. The response of eight fish community indicators to spatio-temporal changes in fishing effort was studied by comparing the rate of change in (i) areas subject to different levels (high, medium, and low) of fishing effort and (ii) areas inside and outside a closed area (the plaice box) where management measures led to changes in fishing effort over time. ...

  13. Coastal Fish Farms Are Settlement Sites for Juvenile Fish

    OpenAIRE

    Fernandez-Jover, Damian; Sanchez-Jerez, Pablo; Bayle-Sempere, Just; Arechavala-Lopez, Pablo; Martinez-Rubio, Laura; Jimenez, Jose Angel Lopez; Lopez, Francisco Javier Martinez

    2009-01-01

    Abstract Two south-west Mediterranean fish farms were monitored over a period of 22 months to test if sea-cage fish farms act as settlement habitats for juvenile fish. Twenty juvenile fish species were found to settle at farms throughout the year. Fish assemblage composition varied markedly over time and was dependent on the spawning period for each species. The most abundant species were Oblada melanura, Atherina spp., Diplodus sargus, Boops boops and Liza aurata. Up to 3783±1730...

  14. Hole migration in the spin-ladder, dimer chain material Sr2.5Ca11.5Cu24O41

    International Nuclear Information System (INIS)

    Complete text of publication follows. The structure of the (SrxCa1-x)14Cu24O41 series contains both Cu2O3 spin ladder layers and CuO2 spin chains. This series is particularly interesting, as the ladders become superconducting under high pressures and with Ca doping. The Sr2.5Ca11.5Cu24O41 stoichiometry displays a Tc of 9 K at 4 GPa. Inelastic neutron scattering has been performed on a single crystal of Sr2.5Ca11.5Cu24O41 with the aim of looking for possible hole migration from the chains to the ladders. Previous measurements [1] on the undoped sample (x = 1) showed all the holes were located on the chains. Our measurements show that, as with the undoped sample, a spin gap is present in the dimer chain with an antiferromagnetic intradimer coupling J1 ? 11 meV between next-nearest-neighbour Cu ions. However, the coupling distance between these dimers is found to be only four units compared to five units for the undoped sample which shows that one in six of the holes has left the chains. Analysis of the ratio of intensities of the scattering from the chains and ladders shows that these holes have migrated to the ladders thus directly supporting the view that hole migration to the ladders is in part responsible for superconductivity. (author)uthor)

  15. Quantum melting of the hole crystal in the spin ladder of Sr14-xCaxCu24O41

    CERN Document Server

    Rusydi, A; Eisaki, H; Fujimaki, Y; Blumberg, G; Uchida, S I; Sawatzky, G A

    2005-01-01

    The "spin ladder" is a reduced-dimensional analogue of the high temperature superconductors that was predicted to exhibit both superconductivity and an electronic charge density wave or "hole crystal" (HC). Both phenomena have been observed in the doped spin ladder system Sr14-xCaxCu24O41 (SCCO), which at x=0 exhibits a HC which is commensurate at all temperatures. To investigate the effects of discommensuration we used resonant soft x-ray scattering (RSXS) to study SCCO as a function of doped hole density, d. The HC forms only with the commensurate wave vectors L_L = 1/5 and L_L = 1/3 and exhibits a simple temperature scaling T_(1/3) / T_(1/5) = 5/3. For irrational wave vectors the HC "melts", perhaps through the motion of topological defects carrying fractional charge.

  16. Electronic Structure Reconstruction across the Antiferromagnetic Transition in TaFe1.23Te3 Spin Ladder

    Science.gov (United States)

    Xu, Min; Wang, Li-Min; Peng, Rui; Ge, Qing-Qin; Chen, Fei; Ye, Zi-Rong; Zhang, Yan; Chen, Su-Di; Xia, Miao; Liu, Rong-Hua; Arita, M.; Shimada, K.; Namatame, H.; Taniguchi, M.; Matsunami, M.; Kimura, S.; Shi, Ming; Chen, Xian-Hui; Yin, Wei-Guo; Ku, Wei; Xie, Bin-Ping; Feng, Dong-Lai

    2015-02-01

    Employing the angle-resolved photoemission spectroscopy we study the electronic structure of TaFe1.23Te3, a two-leg spin ladder compound with a novel antiferromagnetic ground state. Quasi-two-dimensional (2D) Fermi surface is observed, with sizable inter-ladder hopping. Moreover, instead of observing an energy gap at the Fermi surface in the antiferromagnetic state, we observe the shifts of various bands. Combining these observations with density-functional-theory calculations, we propose that the large scale reconstruction of the electronic structure, caused by the interactions between the coexisting itinerant electrons and local moments, is most likely the driving force of the magnetic transition. Thus TaFe1.23Te3 serves as a simpler platform that contains similar ingredients to the parent compounds of iron-based superconductors.

  17. Metodología para el diseño de autómatas finitos con salidas en lenguaje ladder bajo elestándar IEC 61131-3

    Directory of Open Access Journals (Sweden)

    Mauricio Holgu\\u00EDn Londo\\u00F1o

    2011-01-01

    Full Text Available Los autómatas de estados finitos (AF constituyen una metodología de análisis de autómatas comúnmente empleada en el diseño de sistemas lógicos secuenciales. Ellas se pueden interpretar como una subclase de las redes de Petri. En los sistemas lógicos secuenciales se distingue entre su funcionamiento síncrono y asíncrono, seleccionando normalmente la operación síncrona con flancos de un reloj, sin embargo en la implementación de AF en lenguaje ladder no es práctico hacer sensible las entradas de un automatismo a los flancos de un reloj. En el presente artículo se opta por un enfoque asíncrono, se discute una metodología general para la implementación de AF con salida en lenguaje ladder y se afronta el reto de eliminar posibles transiciones no deseadas.

  18. Fish-friendly future

    International Nuclear Information System (INIS)

    The latest US research into ways of reducing the harm to fish from hydroelectric turbines is outlined. Laboratory studies, field studies and advanced computational studies are being carried out to improve the understanding of and reduce the effects of stress and injury to fish from turbines. The Advanced Hydro Turbine System programme is part of the Department of Energy's Hydropower Programme. Turbine passage injuries are caused by a number of mechanisms, leaving the fish either dead or stunned. Advanced turbine technology can help to minimise fish injury and can add dissolved oxygen to the discharged water, thus improving water quality. Turbine modifications are aimed at all species, but studies have focussed on salmon, trout and eels. The new minimum gap runner (MGR) appear as efficient as standard Kaplan turbines

  19. Dehydrofreezing of Fish I

    Science.gov (United States)

    Kozima, Tsuneo

    Recently, new method of removing water from perishable food were developed using dehydration sheet with material having high osmotic pressure and absorbent polymer. Dehydration sheet consist of mixture of sugar dehydrolysate and absorbent polymer covered with sem-permeable membrane, and can remove water in liquid state by contact with perishable food. Dehydration rate of fish using with dehydration sheet varied depending on species, their shape, and ambient temperature etc. Fish were dehydrated with dehydration sheet at low temperature as 0 - 5 C and frozen in cold storage room. Dehydrofrozen fish were kept it's high quality and freshness after thawing, ATPase activity of fish muscle was kept at high level after dehydrofreezing in the case of cod and alaska pollack, and flesh color of farming salmon was kept after thawing.

  20. Fish and Flowers

    Science.gov (United States)

    American Association for the Advancement of Science (; )

    2005-12-05

    We all know rain makes the flowers grow but sometimes fish help too. Thats according to University of Florida ecologist Robert Holt. He and his colleagues studied eight freshwater ponds. There, bees pollinate nearby flowers, while dragonflies prey on the bees. But fish control the dragonfly population by eating their larvae. Holts team compared the flora around ponds with fish to ponds without. Ponds that had fish in them tended to have fewer larval dragonflies, and fewer adult dragonflies which meant more bees, and more frequent pollinations. Plants around fishless ponds, on the other hand, were more likely to be pollen starved. The study suggests one way that the effects of overfishing may ripple onto land. A more complete description of the research and a transcript of the audio file is included. In addition, links to additional resources are included for further inquiry.