A two-cocycle on the group of symplectic diffeomorphisms

We investigate a two-cocycle on the group of symplectic diffeomorphisms of an exact symplectic manifolds defined by Ismagilov, Losik, and Michor and investigate its properties. We provide both vanishing and non-vanishing results and applications to foliated symplectic bundles and to Hamiltonian actions of finitely generated groups.Comment: 16 pages, no figure

Benthic phosphorus cycling within the Eurasian marginal sea ice zone

The Arctic Ocean region is currently undergoing dramatic changes, which will likely alter the nutrient cycles that underpin Arctic marine ecosystems. Phosphate is a key limiting nutrient for marine life but gaps in our understanding of the Arctic phosphorus (P) cycle persist. In this study, we investigate the benthic burial and recycling of phosphorus using sediments and pore waters from the Eurasian Arctic margin, including the Barents Sea slope and the Yermak Plateau. Our results highlight that P is generally lost from sediments with depth during organic matter respiration. On the Yermak Plateau, remobilization of P results in a diffusive flux of P to the seafloor of between 96 and 261 µmol m−2 yr−1. On the Barents Sea slope, diffusive fluxes of P are much larger (1736–2449 µmol m−2 yr−1), but these fluxes are into near-surface sediments rather than to the bottom waters. The difference in cycling on the Barents Sea slope is controlled by higher fluxes of fresh organic matter and active iron cycling. As changes in primary productivity, ocean circulation and glacial melt continue, benthic P cycling is likely to be altered with implications for P imported into the Arctic Ocean Basin

Status and trends in the structure of Arctic benthic food webs

Ongoing climate warming is causing a dramatic loss of sea ice in the Arctic Ocean, and it is projected that the Arctic Ocean will become seasonally ice-free by 2040. Many studies of local Arctic food webs now exist, and with this review paper we aim to synthesize these into a large-scale assessment of the current status of knowledge on the structure of various Arctic marine food webs and their response to climate change, and to sea-ice retreat in particular. Key drivers of ecosystem change and potential consequences for ecosystem functioning and Arctic marine food webs are identified along the sea-ice gradient, with special emphasis on the following regions: seasonally ice-free Barents and Chukchi seas, loose ice pack zone of the Polar Front and Marginal Ice Zone, and permanently sea-ice covered High Arctic. Finally, we identify knowledge gaps in different Arctic marine food webs and provide recommendations for future studie

Benthos

Currently, > 4,000 Arctic macro- and megabenthic species are known, representing the majority of Arctic marine faunal diversity. This estimate is expected to increase. • Benthic invertebrates are food to shes, marine mammals, seabirds and humans, and are commercially harvested. • Traditional Knowledge (TK) emphasizes the link between the benthic species and their predators, such as walrus, and their signi cance to culture. • Decadal changes in benthos biodiversity are observed in some well-studied regions, such as the Barents Sea and Chukchi Sea. • Drivers related to climate-change such as warming, ice decline and acidification are affecting the benthic community on a pan-Arctic scale, while drivers such as trawling, river/glacier discharge and invasive species have signficant impact on regional or local scales. • Increasing numbers of species are moving into, or shifting, their distributions in Arctic waters. These species will outcompete, prey on or offer less nutritious value as prey for Arctic species. • Current monitoring efforts have focused on macro- and megabenthic species, but have been confined to the Chukchi Sea and the Barents Sea. Efforts are increasing in waters of Greenland, Iceland, the Canadian Arctic, and in the Norwegian Sea. All other Arctic Marine Areas are lacking long-term benthic monitoring. • As a first step towards an international collaborative monitoring framework, we recommend to develop a time- and cost-effective, long-term and standardized monitoring of megabenthic communities in all Arctic regions with regular annual groundfish assessment surveys. Expanding monitoring on micro-, meio- and macrobenthic groups is encouraged

Comparison between clinical significance of serum proinflammatory proteins (IL-6 and CRP) and classic tumor markers (CEA and CA 19-9) in gastric cancer

Gastric cancer (GC) is a second most common cause of cancer-related death and represents an inflammation-driven malignancy. It has been suggested that interleukin 6 (IL-6) and C-reactive protein (CRP) play a potential role in the growth and progression of GC. The aim of the present study was to compare clinical significance of IL-6 and CRP with classic tumor markers—carcinoembryonic antigen (CEA) and carbohydrate antigen (CA 19-9) in GC patients. The study included 92 patients with GC and 70 healthy subjects. The serum concentrations of IL-6, CEA and CA 19-9 were determined using immunoenzyme assays, whereas CRP using immunoturbidimetric method. We defined the diagnostic criteria and prognostic value for proteins tested. In GC patients, the serum concentrations of all the proteins tested were significantly higher than in healthy subjects. The IL-6, CEA and CA 19-9 levels correlated with nodal metastases, while CRP with tumor stage, gastric wall invasion, presence of nodal and distant metastases. Diagnostic sensitivity of IL-6 was higher (85%) than those of other markers (CRP 66%, CA 19-9 34%, CEA 22%) and increased in combined use with CRP or CEA (88%). The area under ROC curve for IL-6 was larger than those of CRP and classic tumor markers (CEA and CA 19-9). None of the proteins tested was independent prognostic factor for the survival of GC patients. Our findings indicate better usefulness of serum proinflammatory proteins—IL-6 and CRP than classic tumor markers—CEA and CA 19-9 in the diagnosis of GC