Influence of statistical uncertainty of component reliability estimations on offshore wind farm availability

Offshore wind turbine reliability, one of the industry's biggest sources of uncertainty, is the focus of the present paper. Specifically the impact of uncertain component failure distributions at constant failure rates has been investigated with respect to its implications for wind farm availability. A fully probabilistic offshore wind simulation model has been applied to quantify results; effects shown in this paper underline the significant impact that failure probability distributions have on asset performance evaluation. It was found that wind farm availability numbers may vary in the range up to 20 % just by changing the distributions of failure to a different pattern; in particular those scenarios in which extensive failure accumulation occurred led to significant losses in production. Results are interpreted and discussed mainly from the viewpoint of an offshore wind farm developer, owner and operator, with implications underlined for application in state-of-the-art offshore wind O&M (Operations and Maintenance) models and simulation tools

Downstream Rearing Chinook Salmon (Oncorhynchus tshawytscha) in the Upper Mainstem of the John Day River

Juvenile Chinook Salmon (Oncorhynchus tshawytscha) leave the natal reach at different times and move downstream at different rates which can increase their productivity by allowing them to utilize habitats on different temporal scales and spreading risk of localized stochastic events. This life history diversity can also allow fish to adapt to changing river conditions, thus is an important part of conserving salmon populations. In the spring and summer of 2016 and 2017, I investigated juvenile spring Chinook Salmon in the John Day River, Oregon to identify the abundance, summer distribution, and relative survival of fish following a life history pattern in which they rear in habitats downstream of their natal reach in their first spring (DSR), as opposed to fish that rear in their natal reach and do not move downstream until their second spring (NRR). DSR fish in the John Day River must find cold water refuge to survive lethal water temperatures in the mainstem. Fish were captured in the spring and marked with PIT tags to track their movements and estimate their abundance and survival. In the summer, multiple pass snorkel surveys were conducted in tributaries to investigate summer distribution. NRR fish were also captured and marked in the same time frame to compare the relative survival rates of the two life history types. More than 30,000 and 11,000 sub-yearling fish migrated in 2016 and 2107 respectively, and mainstem water temperature exceeded lethal levels in June of both years. The majority of tributaries within the study area were utilized as thermal refuges, but some of these were dewatered later in the summer. Approximately 13% of tagged fish were detected moving into tributaries in the spring. In most tributaries, summer distribution was limited to the first 1.5 km upstream of the mouth, though in warmer tributaries fish moved upstream farther, with high fish densities detected as far as 43 km from the mainstem John Day River. Averaged across the two years, fish survival to the Columbia River as smolts was 20 times lower for DSR fish marked in the mainstem John Day River than for NRR fish from the same cohort, but for DSR fish that moved into tributaries, survival was only 2.5 times lower than NRR fish, and in 2017 there was no statistical difference between these rates. DSR fish in the John Day River followed an unusual life history variation, and they made longer upstream movements into non-natal tributaries than documented elsewhere. Fish following a DSR life history pattern may have been quite successful in the mainstem John Day River prior to heavy water withdrawals, decreased channel complexity, and altered riparian habitats, but current conditions appear to impair their success compared to NRR fish. The high abundance of DSR fish and the relative performance of those that find thermal refuge in tributaries shows that DSR fish have the potential to make valuable contributions to smolt production despite conditions in the mainstem, but 87% do not appear to find adequate refuge to survive. Increasing the quality and quantity of summer habitat for DSR fish is important to increasing their success and the overall population productivity

Fluorescent Silver Nanoclusters Embedded in Hydrogel Matrix and Its Potential Use in Environmental Monitoring

The optical absorption and fluorescence of silver nanoclusters (AgNCs) are widely exploited in many different application fields such as sensors, bio-imaging, drug delivery, etc. In the sensor field, optical devices are highly versatile thanks to their ease of fabrication and low costs and, therefore, are optimal candidates to replace expensive apparatuses commonly used. In this study, we synthesized AgNCs in aqueous phase by photochemical synthesis using poly methacrylic acid (PMAA) as a stabilizer. Colloidal water solutions of these NCs showed a very good sensitivity to Pb(II) ions, and in order to fabricate a solid-state sensor, we introduced them in a hydrogel material formed by poly(ethylene glycol) diacrylate with a molecular weight of 700 g/mol (PEGDA700). The systems were characterized using absorption and fluorescence spectroscopy and transmission electron microscopy (TEM). Finally, the sensitivity to Pb(II) ions has been tested with the aim to use these systems as solid-state optical sensors for water quality

Fluorescent silver nanoclusters embedded in hydrogel matrix and its potential use in environmental monitoring

The optical absorption and fluorescence of silver nanoclusters (AgNCs) are widely exploited in many different application fields such as sensors, bio-imaging, drug delivery, etc. In the sensor field, optical devices are highly versatile thanks to their ease of fabrication and low costs and, therefore, are optimal candidates to replace expensive apparatuses commonly used. In this study, we synthesized AgNCs in aqueous phase by photochemical synthesis using poly methacrylic acid (PMAA) as a stabilizer. Colloidal water solutions of these NCs showed a very good sensitivity to Pb(II) ions, and in order to fabricate a solid-state sensor, we introduced them in a hydrogel material formed by poly(ethylene glycol) diacrylate with a molecular weight of 700 g/mol (PEGDA(700)). The systems were characterized using absorption and fluorescence spectroscopy and transmission electron microscopy (TEM). Finally, the sensitivity to Pb(II) ions has been tested with the aim to use these systems as solid-state optical sensors for water quality

In-situ nitriding of Fe₂VAl during laser surface remelting to manipulate microstructure and crystalline defects

Tailoring the physical properties of complex materials for targeted applications requires optimizing the microstructure and crystalline defects that influence electrical and thermal transport and mechanical properties. Laser surface remelting can be used to modify the subsurface microstructure of bulk materials and hence manipulate their properties locally. Here, we introduce an approach to perform remelting in a reactive nitrogen atmosphere to form nitrides and induce segregation of nitrogen to structural defects. These defects arise from the fast solidification of the full-Heusler Fe2VAl compound that is a promising thermoelectric material. Advanced scanning electron microscopy, including electron channeling contrast imaging and three-dimensional electron backscatter diffraction, is complemented by atom probe tomography to study the distribution of crystalline defects and their local chemical composition. We reveal a high density of dislocations, which are stable due to their character as geometrically necessary dislocations. At these dislocations and low-angle grain boundaries, we observe segregation of nitrogen and vanadium, which can be enhanced by repeated remelting in nitrogen atmosphere. We propose that this approach can be generalized to other additive manufacturing processes to promote local segregation and precipitation states, thereby manipulating physical properties

Use of domesticated pigs by Mesolithic hunter-gatherers in northwestern Europe

Acknowledgements We thank the Archaeological State Museum Schleswig-Holstein, the Archaeological State Offices of Brandenburg, Lower Saxony and Saxony and the following individuals who provided sample material: Betty Arndt, Jo¨rg Ewersen, Frederick Feulner, Susanne Hanik, Ru¨diger Krause, Jochen Reinhard, Uwe Reuter, Karl-Heinz Ro¨hrig, Maguerita Scha¨fer, Jo¨rg Schibler, Reinhold Schoon, Regina Smolnik, Thomas Terberger and Ingrid Ulbricht. We are grateful to Ulrich Schmo¨lcke, Michael Forster, Peter Forster and Aikaterini Glykou for their support and comments on the manuscript. We also thank many institutions and individuals that provided sample material and access to collections, especially the curators of the Museum fu¨r Naturkunde, Berlin; Muse´um National d0 Histoire Naturelle, Paris; Smithsonian Institution, National Museum of Natural History, Washington D.C.; Zoologische Staatssammlung, Mu¨nchen; Museum fu¨r Haustierkunde, Halle; the American Museum of Natural History, New-York. This work was funded by the Graduate School ‘Human Development in Landscapes’ at Kiel University (CAU) and supported by NERC project Grant NE/F003382/1. Radiocarbon dating was carried out at the Leibniz Laboratory, CAU. This work is licensed under a Creative Commons AttributionNonCommercial-NoDerivs 3.0 Unported License.Peer reviewedPublisher PD

Immunotherapeutic targeting of LIGHT/LTβR/HVEM pathway fully recapitulates the reduced cytotoxic phenotype of LIGHT-deficient T cells.

Tumor necrosis factor (TNF)/TNF receptor (TNFR) superfamily members play essential roles in the development of the different phases of the immune response. Mouse LIGHT (TNFSF14) is a type II transmembrane protein with a C-terminus extracellular TNF homology domain (THD) that assembles in homotrimers and regulates the course of the immune responses by signaling through 2 receptors, the herpes virus entry mediator (HVEM, TNFSFR14) and the lymphotoxin β receptor (LTβR, TNFSFR3). LIGHT is a membrane-bound protein transiently expressed on activated T cells, natural killer (NK) cells and immature dendritic cells that can be proteolytically cleaved by a metalloprotease and released to the extracellular milieu. The immunotherapeutic potential of LIGHT blockade was evaluated in vivo. Administration of an antagonist of LIGHT interaction with its receptors attenuated the course of graft-versus-host reaction and recapitulated the reduced cytotoxic activity of LIGHT-deficient T cells adoptively transferred into non-irradiated semiallogeneic recipients. The lack of LIGHT expression on donor T cells or blockade of LIGHT interaction with its receptors slowed down the rate of T cell proliferation and decreased the frequency of precursor alloreactive T cells, retarding T cell differentiation toward effector T cells. The blockade of LIGHT/LTβR/HVEM pathway was associated with delayed downregulation of interleukin-7Rα and delayed upregulation of inducible costimulatory molecule expression on donor alloreactive CD8 T cells that are typical features of impaired T cell differentiation. These results expose the relevance of LIGHT/LTβR/HVEM interaction for the potential therapeutic control of the allogeneic immune responses mediated by alloreactive CD8 T cells that can contribute to prolong allograft survival