156 research outputs found

    Realistic wave conditions and their influence on quantifying the tidal stream energy resource

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    AbstractWhen selecting suitable sites for tidal stream energy arrays a wide range of factors must be considered, from the magnitude of the tidal stream resource, to realistic oceanographic conditions. Previous computational and laboratory-scale investigations into the impact of waves upon tidal turbines (such as turbine blade loadings) and turbine arrays (such as array configuration) typically assume that waves propagate “inline” to the tidal current (waves following or waves opposing the tidal current with a 20° tolerance limit). We investigated the wave climate at typical tidal stream energy sites across the British Isles. The wave climate was simulated at 18 sites using a 7-year (2005–2011) SWAN wave model simulation of the northwest European shelf seas. The principal semi-diurnal lunar constituent (M2) was also estimated at these sites using the three-dimensional ROMS tidal model. A significant proportion of the wave climate (between 49% and 93% of the time), including extreme wave events (>10m wave heights), was found to be propagating in a direction which was “oblique” to the major axis of tidal flow (i.e. waves which propagate at an angle to the tidal current with a 20° tolerance limit) at all 18 selected sites. Furthermore, the average “inline” wave climate was 2.25m less in height and 2s less in wave period in comparison to the oblique wave climate. To understand the direct effect of waves upon the tidal stream resource, the dynamically wave-tide coupled COAWST modelling system was applied to an idealized headland case study, which represented the typical tide and wave conditions expected at first generation tidal stream energy sites. Waves were found to alter the simulated tidal velocity profile, which, because tidal stream power is proportional to velocity cubed, reduced the theoretical resource by 10% for every metre increase in wave height (R2 94% with 22 degrees of freedom) – depending upon wave period and direction. Our research indicates that wave angle should be considered when quantifying the impact of waves upon tidal turbines, such as computational fluid dynamic (CFD) studies, or laboratory-scale experiments of wake characteristics and turbine fatigue loading. Further, dynamically coupled tide-wave models may be necessary for a thorough resource assessment, since the complex wave-tide interaction affected the tidal resource; however, in situ observations of tidal velocity profiles during a range of wave events will be essential in validating such modelling approaches in the future

    Identification and extraction of streptococcusis gene from streptococcus iniae and recording in Gene Bank

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    S. iniae is an important pathogen in both marin animals and humans, causing systemic infections in these hosts. The symptoms of infections are very similar to symptoms of infections caused by human¬specific streptococcal pathogens. The enzyme phosphoglucomutase (PGM) has recently been discovered to play an important role in polysaccharide capsule production and virulence in s. iniae. We aim to isolate S. iniae and cloning phosphoglucomutase gene. S. iniae grew on sheep blood agar as mucoid and beta- hemolytic colonies after 24 h of incubation at 37C. Then confirmed it by sensitive and rapid method of PCR. The pgm gene was amplified successfully and cloned in pTZ57R cloning vector.The recombinant plasmid was sub cloned into pETDuet-l expression vector by rectriction enzymes and confirmed by PCR. Although S. iniae is a pathogen of economic importance, relatively little is known regarding mechanisms of its pathogenesis and few specific virulence determinants have been established. These include the enzyme phosphoglucomutase which contributes to cell wall integrity and resistance to antimicrobial peptides. Thus, this enzyme is the best choice to product the vaccine and more investigations

    Molecular identification of some causative agents of streptococcosis isolated in farmed rainbow trout (Oncorhynchus mykiss, walbaum) in Iran

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    Streptococcosis is an acute infectious disease that causes mortality in marine and freshwater aquacultures. One of the most important hosts is susceptible to the disease of rainbow trout and during the past decade its industrial production has been growing in Iran. According to FAO, Iran is among the 10 countries producing fish in the world. The most important bacteria causing Strptococcosis includes Strptococcus, Vagococcus and Enterococcus genera. But in all cases, the clinical sings are the same. More than a decade has passed since the first report of this disease in Iran and unfortunately, this disease has become the most important problems of trout production in Iran. Therefor, 72 farms were selected in 8 provinces including Mazandaran, Gilan, Lorestan, CharmahalBakhtiyari, Fars, Kermanshah, Tehran and Kokiloye-Boyer Ahmad and a total 520 moribund and apparently healthy rainbow trout (weight 50 – 200gr) were collected during summer 2008 to 2009. Fish kidney, spleen and liver samples were culture aseptically and finally 206 isolates were identified as gram positive cocci. Using conventional biochemical test, S.uberis, S.agalactiae, S.dysgalactiae, S.faecium and S.inia. Additionally, 172 from 206 isolates were confirmed as S.uberis، S.agalactiae، S.dysgalactiae، S.faecium and S.inia using a PCR assay ased on the results, the most prevalent is belong to S.uberis (isolated from 5 of 7 province), S.dysgalactiae (isolated from 4 of 7 province), S.agalactiae (isolated from 2 of 7 province) and S.faecium and S.inia (from 1 of 7 province) respectively. It is necessary to mention, S.inia was identified just to Fars and any gram positive cocci was isolated from Tehran

    Extended chiral algebras and the emergence of SU(2) quantum numbers in the Coulomb gas

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    We study a set of chiral symmetries contained in degenerate operators beyond the `minimal' sector of the c(p,q) models. For the operators h_{(2j+2)q-1,1}=h_{1,(2j+2)p-1} at conformal weight [ (j+1)p-1 ][ (j+1)q -1 ], for every 2j \in N, we find 2j+1 chiral operators which have quantum numbers of a spin j representation of SU(2). We give a free-field construction of these operators which makes this structure explicit and allows their OPEs to be calculated directly without any use of screening charges. The first non-trivial chiral field in this series, at j=1/2, is a fermionic or para-fermionic doublet. The three chiral bosonic fields, at j=1, generate a closed W-algebra and we calculate the vacuum character of these triplet models.Comment: 23 pages Late

    Effect of Echinacea purpurea and Astragalus glycyphyllos on immune responses of rainbow trout (O. mykiss) and resistance to sterptococcosis

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    Nowadays, medical plants extract is used in aquaculture industry to enhance growth, immune system and fish resistance to different pathogens. In this study, some non-specific immune responses, hematology and biochemical parameters in rainbow trout juveniles (16 gr mean weight) and their resistance to Streptococcus iniae were evaluated following oral administration of Echinacea purpurea and Astragalus sp. extract. Three concentrations (0.5, 1 and 1.5 gr/kg of feed) of Echinacea purpurea and three concentrations (2, 3 and 5 gr/kg of feed) of Astragalus sp extract and control group were used for 60 days. Parameters evaluated included: levels of C4, C3 (complement components), free oxygen radicals (respiratory burst), Lysozyme, numbers of lymphocytes, monocytes and neutrophils. In the end, the relative survival rate (RSR) of fish was evaluated against S. iniae. The results showed that the levels of C3, lysozyme, oxygen free radicals, the number of neutrophils and lymphocytes in the experiment groups (the highest dose) compared to control group were increased significantly (p 0.05). The relative survival rates of fish following challenge with Streptococcus iniae, were 91/11, 93/33 and 44/44 percent in experiments (Echinacea purpurea and Astragalus sp.) and control groups, respectively. In conclusion, it may be state that Echinacea purpurea and Astragalus sp. extracts enhance the non-specific immune system and fish resistance against Streptococcusis, and it seems it can be used as immunostimulant in feed

    Amniotic membrane seeded with mesenchymal adipose-derived stem cell for coverage of wound in third degree burn: An experimental study

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    Methods: This study was experimental and has been done in Burn Research Center of Iran University of Medical Sciences during January 2012 to April 2013. Thirty rats randomly divided to three equal groups. Inguinal fat of 10 rats (one group) were used for preparation of autologous adipose-derived mesenchymal stem cells. Acellular amnion was used as a scaffold for stem cell transfer. Each of the thirty rats had been exposed to a cm deep 3rd degree burn on back area. 24 hours after surgery, the wound was excised and it had been covered by three methods: conventional dressing in the first group, acellular amnion in the second group and acellular amnion seeded with adipose-derived stem cell in the third group. The rate of wound healing and pathologic characteristics was compared in all three groups. Results: Healing rate and decrease in wounds size was significantly better in acellular amnion seeded with adipose- derived stem cells compared with other two groups at 3rd and 15th days after surgery P<0.01. Also in histopathology examination, fibroplasia and neovascularization of wounds were significantly better in stem cells group than the other two groups P<0.001. Conclusion: Acellular amnion seeded with adipose-derived stem cell can result in faster wound healing and better histopathology characteristic. The amnion as a scaffold and the fat derived stem cells as healing accelerator are recommended for coverage of the 3rd degree burn wounds after excision and it may reduce the need for skin graft. Background: Stem cells are applied in the treatment of wide range of diseases and can be separated from different tissues of the body. These cells can treat diseases by cytokine and growth factor secretion and also cell differentiation. Burn wound is a challenging problem of reconstructive surgery and stem cells may help wound healing process. We designed this study to evaluate the beneficial effect of fat derived stem cells for coverage of 3rd degree burn wound. © 2014, Tehran University of Medical Sciences (TUMS). All rights reserved

    Investigation of Changing Pore Topology and Porosity during Matrix Acidizing using Different Chelating Agents

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    Core flooding acidizing experiments on sandstone/carbonate formation are usually performed in the laboratory to observe different physical phenomena and to design acidizing stimulation jobs for the field. During the tests, some key parameters are analyzed such as pore volume required for breakthrough as well as pressure. Hydrochloric acid (HCl) is commonly used in the carbonate matrix acidizing while Mud acid (HF: HCl) is usually applied during the sandstone acidizing to remove damage around the well bore. However, many problems are associated with the application of these acids, such as fast reaction, corrosion and incompatibility of HCl with some minerals (illite). To overcome these problems, chelating agents (HEDTA, EDTA and GLDA) were used in this research. Colton tight sandstone and Guelph Dolomite core samples were used in this study. The experiments usually are defined in terms of porosity, permeability, dissolution and pore topology. Effluent samples were analyzed to determine dissolved iron, sodium, potassium, calcium and other positive ions using Inductively Coupled Plasma (ICP). Meanwhile Nuclear Magnetic Resonance (NMR) was employed to determine porosity and pore structure of the core sample. Core flood experiments on Berea sandstone cores and dolomite samples with dimensions of 1.5 in × 3 in were conducted at a flow rate of 1 cc/min under 150oF temperature. NMR and porosity analysis concluded that applied chemicals are effective in creating fresh pore spaces. ICP analysis concluded that HEDTA showed good ability to chelate calcium, sodium, magnesium, potassium and iron. It can be established from the analysis that HEDTA can increase more amount of permeability as compared to other chelates

    Revista de Vertebrados de la Estación Biológica de Doñana

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    Página 298 con error de impresiónEstudio cariológico en dos especies de Serránidos del Mediterráneo (Peces: PerciformesRelaciones morfométricas de Atherina boyeri Risso (Pisces: Atherinidae) de la laguna de Zoñar (Córdoba, España)Contribución al conocimiento de la biometríay osteología de Barbus barbus bocagei, Steindachner, 1866 (Pisces: CyprinidaeLa actividad de la salamandra, Salamandra salamandra (L.), en Galicia.Estudios sobre el sapo corredor (Bufo calamita) en el Sur de España.1. BiometríaEstudios sobre el sapo corredor (Bufo calamita) en el Sur de España. II. AlimentaciónBiología de la reproducción de Rana iberica Boulenger 1879 en zonas simpátridas con Rana temporaria Linneo, 1758Nuevos datos sobre la distribución geográfica de Lacerta monticola cantabrica Mertens, 1929. (Sauria, lacertidae).Datos sobre Lacerta monticola Boulenger, 1905 (Saurio: lacertidae)en el oeste del Sistema Central.Nueva especie de Anolis (lacertilia, Iguanidae) para CubaEtograma cuantificado del cortejo en Falco naumannOntogénesis del comportamiento predador en Falco naumanniContaminación xenobiótica del Parque Nacional de Doñana. 1. Residuos de insecticidas organoclorados, bifenilos policlorados y mercurio en anseriformes y gruiformesReproducción del críalo (Clamator glandarius) en Sierra Morena CentraNidificación de Picus viridis en taludes de arcilla en Ramblas de Guadix (Granada)Comportamiento del calamón Porphyrio porphyrio (Linnaeus, 1758) en Doñana, Marismas del GuadalquiviBiología y ecología de la malvasía (Oxyura leucocephala) en Andalucía.On the differential diet of Carnivora in islands:a method for analysing it and a particular case.Notas sobre la distribución pasada y actual del meloncillo Herpestes ichneumon (L.) en la Península IbéricaEstructuración de las interacciones en una camada de lobos (Canís lupus)Nuevos datos sobre la distribución del Cottus gobio L. (pisces, cottidae) en EspañaSobre la alimentación de Callopistes maculatus (Reptilia,teiidaeObservación de Lacerta lepida depredando un nido de Alectoris rufaNueva cita del galápago leproso Mauremys leprosa (Scheigger, 1812) en los pirineosPrimera cita de Psammodromus hispanicus (Fitzinger) para GaliciaSobre la presencia de Gallotia (=Lacerta) atlantica (Peters y Doria, 1882) en Gran CanariaNota sobre las Lacerta monticola Boulenger, 1905 de las zonas del norte de GaliciaPrimeras notas herpetológicas de la provincia de Soria.Datos sobre selección de hábitat y ecología alimenticia del porrón pardo (Aythya nyroca)Probable nueva área de cría del pechiazul (Luscinia svecica cyanecula) en el sistema central. PerisPredación de Falco peregrinus y Falco subbuteo sobre quirópterosResultados de la producción de Oxyura leucocephala en el año 1981 en las lagunas de Zóñar y el rincónAnálisis de la dieta de Tyto alba en un medio árido antropógeno de los alrededores de Almería¿Son Eudocimus ruber y E. albus distintas especies?EL Estornino pinto (Sturnus vulgaris) en Canarias: nueva especie nidifiante en el archipiélagoDatos sobre la alimentación otoñal del cárabo (Strix aluco) en la sierra de CádizObservación primaveral de rapaces y otras aves en el páramo del estado de Mérida (Venezuela).Murciélago hematófago (Desmodus rotundus) parasitando a un chigüire (Hidrochoerus hydrochaeris)Observaciones sobre la reproducción del zacatuche o teporinho Romerolagus diazi (Mammalia: lagomorpha)Estudio electroforético de hemoglobinas y esterasas sanguíneas en Rhinolophus ferrumequinum (Chiroptera: rhinolophidae) y de hemoglobinas en Tadaria taeniotis (chiroptera: molossidae)Peer reviewe

    Production of bacterial probiotic from trout (Oncorhynchus mykiss) for improvement of immune system and challenge to streptococcosis

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    This study was conducted for the first time and the effects of probiotic bacteria isolated from the gut of Rainbow trout (Oncorhynchus mykiss). In the first step, after the purification of the isolated bacteria, probiotic properties in vitro was assessed with injection to healthy fish and challenge with three species of pathogenic bacteria in culture media. The second phase of the bacteria isolated in 5 treatments (log 7, 8 and 9 of the lactic bacteria (LAB), Vibrio sp and Pseudomonas sp) and a control treatment on growth and survival, hematological parameters (RBC and WBC cells), immunology and physiology parameters tested during the 60 days of the above parameters after 30 and 60 days and finally at the end, the final assessment was Streptococcosis resistance in fish. The results showed that the isolated bacteria were able to enhance the growth parameters (weight, feed conversion, feed fat, protein efficiency ratio and specific growth rate) and survival. The results showed that log 8 LAB was significant difference with other treatments and control. When using log 8 LAB and Vibrio, the MCV, MCH and MCHC were decreased with no significant difference. The log 8 has the greatest effect on the amount of liver enzyme (AST), IgM and complement component C3, and had significant difference with other treatments. The challenge examination to Streptococcus iniae showed the highest survival in treatments with log 8 (96.66%), and Vibrio (93.33%) and then subjected to other treatments and control are also the least survival (25.38%). The conclusion of that study is the first probiotic properties of bacteria isolated from trout to changes in quality indicators are in particular the LAB bacteria and the second log 8 of LAB had significant positive of changes development and safety, and the fish are resistanted against Streptococcosis
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