Vertical swimming events (VSEs) of the Japanese flounder, Paralichthys olivaceus, recorded by high-frequency depth data loggers, were analysed to identify spawning events. In total 25,907 VSEs from ...10 adult fish were classified into 4 clusters using a k-means method. VSEs in a specific cluster (cluster-S) characterised by accelerated vertical swimming were identified as possible spawning events. Both the descent (0.43 ± 0.22 body length s− 1) and ascent rates (0.43 ± 0.24 body length s− 1) of VSEs in cluster-S were more than 4 times faster than in any other VSE. Our analyses indicated that 4 individuals exhibited the spawning events during the recording periods. The estimated spawning frequency ranged from 0.74 to 0.90 events day− 1. These values were comparable to those obtained in other field and laboratory studies. The spawning condition of fish at the time of recapture was confirmed by separate histological and anatomical observations, which supported the cluster analysis results. These results suggest that a clustering technique can be successfully applied to identify spawning behaviour from time-depth data of free-swimming flatfishes that exhibit vertical swimming movements.
This paper proposes a behavior analysis system for quantitative evaluation of infants with attention deficit hyperactivity disorder (ADHD) using video images. The system records infantsʼ movements ...using video cameras without any markers, and quantitatively evaluates each infantʼs behavior using features extracted from video images based on the behavior model. In the experiments performed, behaviors of infants in nursery school were evaluated using the proposed system. The results showed that the behavior of a high-risk infant significantly different from those of normal infants. These outcomes indicated that the proposed system could discriminate the behavior of normal infants and high-risk infants.
We present a polarimetric map of a 20'x20' area toward the Galactic center. The polarization of point sources has been measured in the J, H, and Ks bands using the near-infrared polarimetric camera ...SIRPOL on the 1.4 m telescope IRSF. One percent or better accuracy of polarization degree is achieved for sources with J<14.5, H<13.5, and Ks<12.0. Comparing the Stokes parameters between high extinction stars and relatively low extinction ones, we have obtained a polarization originating from magnetically aligned dust grains at the central region of our Galaxy of at most 1-2 kpc. The distribution of the position angles shows a peak at about 20 deg, nearly parallel to the Galactic plane, suggesting a toroidal magnetic configuration. The derived direction of the magnetic field is in good agreement with that obtained from far-infrared/submillimeter observations, which detect polarized thermal emission from dust in the molecular clouds at the Galactic center. Our results show that by subtracting foreground components, near-infrared polarimetry allows investigation of the magnetic field structure "at" the Galactic center.
We have conducted deep JHKs imaging polarimetry of a ~8' x 8' area of the NGC
2071 star forming region. Our polarization data have revealed various infrared
reflection nebulae (IRNe) associated with ...the central IR young star cluster
NGC2071IR and identified their illuminating sources. There are at least 4 IRNe
in NGC2071IR and several additional IRNe are identified around nearby young
stars in the same field-of-view. Each illuminating source coincides with a
known near-IR source except for IRS3, which is only a part of IRN2 and is
illuminated by the radio source 1c. Aperture polarimetry of each cluster source
is used to detect unresolved circumstellar disk/outflow systems. Aperture
polarimetry of the other point-like sources within the field is made in this
region for the first time. The magnetic field structures (from ~1 pc down to
\~0.1 pc) are derived using both aperture polarimetry of the point-like sources
and imaging polarimetry of the shocked H2 emission that is seen as the dominant
knotty nebulae in the Ks band image; they are both of dichroic origin and the
derived field directions are consistent with each other. The magnetic field
direction projected on the sky is also consistent with that inferred from the
850 micron thermal continuum emission polarimetry of the central 0.2 pc region,
but running roughly perpendicular (~75 degrees) to the direction of the large
scale outflow. We argue that the field strength is too weak to align the
outflow in the large scale field direction via magnetic braking.
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