Abstract.A homogenization method to model a stack of second generation (2G) High Temperature Superconducting (HTS) tapes under AC applied transport current or magnetic field has been obtained. The idea is to find an anisotropic bulk equivalent for the stack, such that the geometrical layout of the internal alternating structures of insulating, metallic, superconducting and substrate layers is "washed" out while keeping the overall electromagnetic behavior of the original stack. We disregard assumptions upon the shape of the critical region and use a power law E-J relationship allowing for overcritical current densities to be considered. The method presented here allows for a computational speedup factor of up to 2 orders of magnitude when compared to full 2-D simulations taking into account the actual dimensions of the stacks without compromising accuracy.

No abstract

The newly described piscine reovirus (PRV) appears to be associated with the development of heart and skeletal muscle inflammation (HSMI) in farmed Atlantic salmon Salmo salar L. PRV seems to be ubiquitous among fish in Norwegian salmon farms, but high viral loads and tissue distribution support a causal relationship between virus and disease. In order to improve understanding of the distribution of PRV in the salmon production line, we quantified PRV by using realtime PCR on heart samples collected at different points in the life cycle from pre-smolts to fish ready for slaughter. PRV positive pre-smolts were found in about 36% of the freshwater cohorts and a general increase in viral load was observed after their transfer to seawater. A reduction in viral loads was recorded when fish approached slaughter (18 mo in sea cages). Sequencing of positive samples did not support the hypothesis that outbreaks are caused by the spreading of a particular (virulent) strain of PRV. KEY WORDS: Piscine reovirus · PCR · Salmon · Aquaculture · HSMI Resale or republication not permitted without written consent of the publisherDis Aquat Org 99: [7][8][9][10][11][12] 2012 After initial success with experimental transmission of the disease (Kongtorp et al. 2004a), HSMI was recently linked to a novel reovirus, piscine reovirus (PRV) (Palacios et al. 2010). Although the virus appears to be ubiquitous in Norwegian salmon farms, elevated viral loads are associated with outbreaks of HSMI (Palacios et al. 2010). A causal relationship is also supported by in situ hybridisation using formalin-fixed heart tissue where a correlation between the presence of viral nucleic acids and histopathological lesions has been found (Palacios et al. 2010). PRV has been detected in healthy, wild salmon, albeit with lower prevalence and virus load. The virus has also been found in archive samples taken from salmon in the late 1980s and also in rainbow trout Oncorhynchus mykiss Walbaum (Palacios et al. 2010). Farmed Atlantic salmon with HSMI-like lesions have also been reported from Scotland (Ferguson et al. 2005).In the present study we quantified PRV loads at various stages in the Atlantic salmon production line, from pre-smolts in fresh water to fish ready for slaughter. Samples were collected from farms where no heart lesions were observed and from farms with clinical outbreaks of HSMI. We also sequenced parts of the PRV genome detected in different samples in order to investigate the molecular epidemiology of the virus and potentially virulent PRV strains. Our results indicate that PRV is a ubiquitous virus in Norwegian fish farms and that careful virus quantification and/or study of tissue distribution of viral particles/genomes need to be complemented with his topathology for correct diagnoses. The results should be useful when interpreting PRV loads both in the context of HSMI/PRV epidemiology and diagnosis. MATERIALS AND METHODSViral loads were established for 2 sets of samples; one set of 171 field samples was collected from 23 mar...

Pancreas disease (PD) caused by salmonid alphavirus (SAV) has a significant negative economic impact in the salmonid fish farming industry in northern Europe. Until recently, only SAV subtype 3 was present in Norwegian fish farms. However, in 2011, a marine SAV 2 subtype was detected in a fish farm outside the PD-endemic zone. This subtype has spread rapidly among fish farms in mid-Norway. The PD mortality in several farms has been lower than expected, although high mortality has also been reported. In this situation, the industry and the authorities needed scientific-based information about the virulence of the marine SAV 2 strain in Norway to decide how to handle this new situation. Atlantic salmon post-smolts were experimentally infected with SAV 2 and SAV 3 strains from six different PD cases in Norway. SAV 3-infected fish showed higher mortality than SAV 2-infected fish. Among the SAV 3 isolates, two isolates gave higher mortality than the third one. At the end of the experiment, fish in all SAV-infected groups had significantly lower weight than the uninfected control fish. This is the first published paper on PD to document that waterborne infection produced significantly higher mortality than intraperitoneal injection.

Pancreas disease (PD) is a viral disease caused by Salmonid alphavirus (SAV) that affects farmed Atlantic salmon (Salmo salar L.) and rainbow trout (Oncorhynchus mykiss (Walbaum)) in the seawater phase. Since its first description in Scotland in 1976, a large number of studies have been conducted relating to the disease itself and to factors contributing to agent spread and disease occurrence. This paper summarizes the currently available, scientific information on the epidemiology of PD and its associated mitigation and control measures. Available literature shows infected farmed salmonids to be the main reservoir of SAV. Transmission between seawater sites occurs mainly passively by water currents or actively through human activity coupled with inadequate biosecurity measures. All available information suggests that the current fallowing procedures are adequate to prevent agent survival within the environment through the fallowing period and thus that a repeated disease outbreak at the same site is due to a new agent introduction. There has been no scientific evaluation of currently used on-site biosecurity measures, and there is limited information on the impact of available mitigation measures and control strategies.