113 research outputs found
Overview of research on tuna thermo-physiology using electric tags
The behavioral physiology of bigeye tuna was investigated using acoustic tags in the 1990s. They spend most of the daylight hours below the thermocline but make regular brief excursions into the mixed layer. In doing so, they reduce the efficacy of their vascular countercurrent heat exchangers while gaining heat from the warmer environment and then increase it again when they return below the thermocline. Recently, archival tags have been used on a range of tuna species including bluefin. This tag, recovered when the tuna is harvested, yields time-series data over longer periods than acoustic tags. Although immature Pacific bluefin spend most of their time at the surface, they often dive below the thermocline, maintaining a peritoneal temperature. This might be due either to heat conservation or high heat production. Further, while giant Atlantic bluefin show an ability to maintain their temperature above the ambient, there are occasions in cold water when some physiological process is clearly limiting their dive time. Solution of the growth conundrum that their warm body temperature may pose an ecological problem as they grow in body mass, should be clarified by using tag data. This will lead to investigation of their adaptation mechanisms to their habitats
Normal-state properties of the antiperovskite oxide SrSnO revealed by Sn-NMR
We have performed Sn-NMR measurements on the antiperovskite oxide
superconductor SrSnO to investigate how its normal state changes with
the Sr deficiency. A two-peak structure was observed in the NMR spectra of all
the measured samples. This suggests that the phase separation tends to occur
between the nearly stoichiometric and heavily Sr-deficient SrSnO
phases. The measurement of the nuclear spin-lattice relaxation rate
indicates that the Sr-deficient phase shows a conventional metallic behavior
due to the heavy hole doping. In contrast, the nearly stoichiometric phase
exhibits unusual temperature dependence of , attributable to the
presence of a Dirac-electron band.Comment: 5 pages, 4 figure
S-wave Superconductivity in the Dirac Line-nodal Material CaSb2
We performed 121/123Sb-nuclear quadrupole resonance (NQR) measurements on the
superconducting (SC) line-nodal material CaSb2 in order to investigate
electronic properties in the normal and SC states from a microscopic point of
view. In the normal state, the nuclear spin-lattice relaxation rate 1/T1 for
the Sb(1) site, which is responsible for the line-nodal parts, is approximately
proportional to temperature, indicating the conventional Fermi liquid state.
From comparison with band structure calculations, it is considered that the NQR
properties related to the line-nodal character are hidden because the
conventional behavior originating from Fermi-surface parts away from the nodes
is dominant. In the SC state, a clear coherence peak just below the transition
temperature and an exponential decrease at lower temperatures were observed in
1/T1. These results strongly suggest that conventional s-wave superconductivity
with a full gap is realized in CaSb2.Comment: 6 pages, 5 figure
Diving patterns and performance of Pacific bluefin tuna (Thunnus thynnus orientalis) as recorded by archival tags
Archival tagged immature Pacific bluefin tuna were released off Tsushima Island in the East China Sea. Time-series data on swimming depth, ambient temperature, internal body temperature, and light intensity were recorded every 128s to evaluate : 1) their vertical swimming patterns to depths below the thermocline and 2) the development of their diving performance with growth. In summer, the tuna spent most of their time at the surface, but occasionally dove to depths below the thermocline during the daytime, and at dawn and dusk. In addition, bluefin dove at increasing descent rates and surfaced more slowly when they made excursions to deeper depths. Larger-sized bluefin dove to much deeper depths than smaller individuals, suggesting that the diving performance of bluefin is related to their body size and larger size enables them to expand their vertical movement range
The factors limiting the diagnostic accuracy of myocardial perfusion cardiac magnetic resonance imaging: coronary flow reserve and amount of myocardial scar
Semantic Scene Difference Detection in Daily Life Patroling by Mobile Robots using Pre-Trained Large-Scale Vision-Language Model
It is important for daily life support robots to detect changes in their
environment and perform tasks. In the field of anomaly detection in computer
vision, probabilistic and deep learning methods have been used to calculate the
image distance. These methods calculate distances by focusing on image pixels.
In contrast, this study aims to detect semantic changes in the daily life
environment using the current development of large-scale vision-language
models. Using its Visual Question Answering (VQA) model, we propose a method to
detect semantic changes by applying multiple questions to a reference image and
a current image and obtaining answers in the form of sentences. Unlike deep
learning-based methods in anomaly detection, this method does not require any
training or fine-tuning, is not affected by noise, and is sensitive to semantic
state changes in the real world. In our experiments, we demonstrated the
effectiveness of this method by applying it to a patrol task in a real-life
environment using a mobile robot, Fetch Mobile Manipulator. In the future, it
may be possible to add explanatory power to changes in the daily life
environment through spoken language.Comment: Accepted to 2023 IEEE/RSJ International Conference on Intelligent
Robots and Systems (IROS 2023
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