Annual cycle of benthic nutrient fluxes in Tomales Bay, California, and contribution of the benthos to total ecosystem metabolism

Benthic fluxes of dissolved nutrients, oxygen, dissolved inorganic carbon, and total alkalinity were measured over a 2 yr period in Tomales Bay, California, USA, using in situ incubation chambers. Release of dissolved nutrients from the sediment peaked in late summer and was lowest in winter. The difference between C:N: P flux ratios and composition of suspended particulates indicated the existence of a sink for regenerated N, relative to C and P. Total alkalinity flux revealed that carbon metabolism by net sulfate reduction represented ca one-third of total benthic metabohsm Partitioning net system fluxes into component fluxes suggested that the equivalent of ca 70 to 80 % of the available particulate C, N and P was respired within the water column, while about 20 to 30 O/O was respired by the benthos. During spring, increasing light resulted in higher water column productivity, followed closely by rising water column respiration. With low delivery of the new organic material to the benthos, and low residual organics in the sediment, benthic respiration remained low. Fallout of particulate material, coinciding with peak water temperature in late summer, resulted in a 'crossover' with benthic respiration temporarily exceeding water column respiration

Construction status and prospects of the Hyper-Kamiokande project

The Hyper-Kamiokande project is a 258-kton Water Cherenkov together with a 1.3-MW high-intensity neutrino beam from the Japan Proton Accelerator Research Complex (J-PARC). The inner detector with 186-kton fiducial volume is viewed by 20-inch photomultiplier tubes (PMTs) and multi-PMT modules, and thereby provides state-of-the-art of Cherenkov ring reconstruction with thresholds in the range of few MeVs. The project is expected to lead to precision neutrino oscillation studies, especially neutrino CP violation, nucleon decay searches, and low energy neutrino astronomy. In 2020, the project was officially approved and construction of the far detector was started at Kamioka. In 2021, the excavation of the access tunnel and initial mass production of the newly developed 20-inch PMTs was also started. In this paper, we present a basic overview of the project and the latest updates on the construction status of the project, which is expected to commence operation in 2027

Prospects for neutrino astrophysics with Hyper-Kamiokande

Hyper-Kamiokande is a multi-purpose next generation neutrino experiment. The detector is a two-layered cylindrical shape ultra-pure water tank, with its height of 64 m and diameter of 71 m. The inner detector will be surrounded by tens of thousands of twenty-inch photosensors and multi-PMT modules to detect water Cherenkov radiation due to the charged particles and provide our fiducial volume of 188 kt. This detection technique is established by Kamiokande and Super-Kamiokande. As the successor of these experiments, Hyper-K will be located deep underground, 600 m below Mt. Tochibora at Kamioka in Japan to reduce cosmic-ray backgrounds. Besides our physics program with accelerator neutrino, atmospheric neutrino and proton decay, neutrino astrophysics is an important research topic for Hyper-K. With its fruitful physics research programs, Hyper-K will play a critical role in the next neutrino physics frontier. It will also provide important information via astrophysical neutrino measurements, i.e., solar neutrino, supernova burst neutrinos and supernova relic neutrino. Here, we will discuss the physics potential of Hyper-K neutrino astrophysics

Anisotropic stratification beneath Africa from joint inversion of SKS and P receiver functions

International audienceThe analysis of rock anisotropy revealed by seismic waves provides fundamental constraints on stress-strain field in the lithosphere and asthenosphere. Nevertheless, the anisotropic models resolved for the crust and the upper mantle using seismic waves sometimes show substantial discrepancies depending on the type of data analyzed. In particular, at several permanent stations located in Africa, previous studies revealed that the observations of SKS splitting are accounted for by models with a single and homogeneous anisotropic layer whereas 3-D tomographic models derived from surface waves exhibit clear anisotropic stratification. Here we tackle the issue of depth-dependent anisotropy by performing joint inversion of receiver functions (RF) and SKS waveforms at four permanent broadband stations along the East African Rift System (EARS) and also on the Congo Craton. For three out of the four stations studied, stratified models allow for the best fit of the data. The vertical variations in the anisotropic pattern show interesting correlations with changes in the thermomechanical state of the mantle associated with the lithosphere-asthenosphere transition and with the presence of hot mantle beneath the Afar region and beneath the EARS branches that surround the Tanzanian Craton. Our interpretation is consistent with the conclusion of earlier studies that suggest that beneath individual stations, multiple sources of anisotropy, chiefly olivine lattice preferred orientation and melt pocket shape preferred orientation in our case, exist at different depths. Our study further emphasizes that multiple layers of anisotropy must often be considered to obtain realistic models of the crust and upper mantle

Structural Stability

IASS-IACM 2008 Session: Structural Stability -- Session Organizer: Herbert MANG (Technical University of Vienna) -- Plenary Lecture: Abstract, Slides and Video: "Answers to three not quite straightforward questions in structural stability" by Andreas STEINBOECK, Gerhard HOEFINGER, Xin JIA, Herbert A. MANG (Technical University of Vienna) -- Keynote Lecture: "Limit-point and postbuckling behavior of steel trusses under thermal and mechanical loadings" by Yeong Bin YANG , T.J. LIN (National Taiwan University) -- "Modeling thin-walled cold-formed steel members and systems" by Benjamin W. SCHAFER , R. H. SANGREE, Cristopher MOEN, M. SEIF, Y. SHIFFERAW, V. ZEINODDINI, Z. J. LI, O. IUORIO, Y. GUAN (Johns Hopkins University) -- "Multi parametrical instability of straight bars" by Jan B. OBREBSKI (Warsaw University of Technology) -- "The effect of predetermined delaminations on buckling and post-buckling behavior of spatial composite timber beams and frames" by Miran SAJE , Urban RODMAN, Dejan ZUPAN, Igor PLANINC (University of Ljubljana) -- Keynote Lecture: "Buckling and sensitivity analysis of imperfect shells involving contact" by Karl SCHWEIZERHOF , Eduard EWERT (University of Karlsruhe) -- Keynote Lecture: "Determining the stability of tensegrities and generic global rigidity" by Robert CONNELLY (Cornell University) -- "Initial imperfection identification in shell buckling problems" by Christopher J. STULL , Christopher J. EARLS, Wilkins AQUINO (Cornell University) -- "Buckling phenomena, analysis and design of axially compressed cylindrical shells with co-existent external pressure" by Werner GUGGENBERGER , Medhanye B. TEKLEAB (TU Graz