STRAW-b (STRings for Absorption length in Water-b): the second pathfinder mission for the Pacific Ocean Neutrino Experiment

Since 2018, the potential for a high-energy neutrino telescope, named the Pacific Ocean Neutrino Experiment (P-ONE), has been thoroughly examined by two pathfinder missions, STRAW and STRAW-b, short for short for Strings for Absorption Length in Water. The P-ONE project seeks to install a neutrino detector with a one cubic kilometer volume in the Cascadia Basin's deep marine surroundings, situated near the western shores of Vancouver Island, Canada. To assess the environmental conditions and feasibility of constructing a neutrino detector of that scale, the pathfinder missions, STRAW and STRAW-b, have been deployed at a depth of 2.7 km within the designated site for P-ONE and were connected to the NEPTUNE observatory, operated by Ocean Networks Canada (ONC). While STRAW focused on analyzing the optical properties of water in the Cascadia Basin, \ac{strawb} employed cameras and spectrometers to investigate the characteristics of bioluminescence in the deep-sea environment. This report introduces the STRAW-b concept, covering its scientific objectives and the instrumentation used. Furthermore, it discusses the design considerations implemented to guarantee a secure and dependable deployment process of STRAW-b. Additionally, it showcases the data collected by battery-powered loggers, which monitored the mechanical stress on the equipment throughout the deployment. The report also offers an overview of STRAW-b's operation, with a specific emphasis on the notable advancements achieved in the data acquisition (DAQ) system and its successful integration with the server infrastructure of ONC.Comment: 20 pages, 11 figures, 2 table

The effect of shortening on crossbridge dynamics in cardiac muscle

Bibliography: p. 96-105Landesberg and Sideman have proposed a model for cross-bridge cycling where the rate constant for crossbridge weakening, G, is a function of the sarcomere shortening velocity such that G = G0 + G1 • V , where G0 is the rate constant in the isometric state and G\ is the mechanical feedback. The effect of myosin heavy chain isoform on G1 is unknown. Methods: Rats were made to express either pure α-MHC, by treatment with thyroid hormone (T3), or pure ß-MHC, by treatment with PTU. Force-velocity curves were obtained from cardiac trabeculae (Ca2+ = 1.5 mM, 25°C). To determine G1, ~FN the instantaneous force difference between a shortening and isometric contraction was measured. Results: The sarcomere shortening velocity of T3 rats were twice that of PTU treated rats at all levels of relative load (VMAX= 15.99 µm/s - T3, 8.95 µm/s - PTU). There was no difference in the curvature of the force-velocity relationship between the two groups. G1 as measured from slow ( ≤ 4 µm/s) releases was 4.76 /µm (STD DEV = 1.43) for T3 rats and 4.88 /µm (STD DEV = 1.29) for PTU rats

Two-year optical site characterization for the Pacific Ocean Neutrino Experiment (P-ONE) in the Cascadia Basin

The STRings for Absorption length in Water (STRAW) are the first in a series of pathfinders for the Pacific Ocean Neutrino Experiment (P-ONE), a future large-scale neutrino telescope in the north-eastern Pacific Ocean. STRAW consists of two $$150\,\mathrm {m}$$ long mooring lines instrumented with optical emitters and detectors. The pathfinder is designed to measure the attenuation length of the water and perform a long-term assessment of the optical background at the future P-ONE site. After 2 years of continuous operation, measurements from STRAW show an optical attenuation length of about 28 m at $$450\,\mathrm {nm}$$. Additionally, the data allow a study of the ambient undersea background. The overall optical environment reported here is comparable to other deep-water neutrino telescopes and qualifies the site for the deployment of P-ONE