Thermoluminescence studies of ordinary chondrites in the Japanese Antarctic meteorite collection, III: Asuka and Yamato type 3

We measured thermoluminescence (TL) properties of 37 Asuka and 13 Yamato type 3 ordinary chondrites from Japanese Antarctic meteorite collection for determining subtypes and pairing. Most of the meteorites are of petrologic type 3.6-3.9; however, we found three primitive ordinary chondrites (A-9043,A-87319 and Y-793384) of petrologic type ≦3.1. We found 22 TL potential pairing groups in 26 Asuka H3 chondrites comprising a chain of pairing groups, which implies an H3 chondrite shower near the Asuka area

Improvement of the Vibration Prediction of a Poppet Valve in a Cavitation State

Poppet valves are popular components of hydraulic systems, but they sometimes induce vibration in these systems. In particular, the vibration phenomenon of a poppet valve in a cavitation state is a troublesome problem in hydraulic systems, because the dynamic effects of cavitation on the poppet valve are difficult to predict. In this research, we investigated the vibration phenomenon of the poppet valve in the cavitation state in a visualization experiment and numerical simulation. We found in numerical simulation that it is possible to predict the tendency of the vibration by assuming that the bulk modulus of hydraulic oil is affected by the ratio of cavitation bubbles mixed in the oil. Additionally, we proposed a simple method of estimating the quantity of cavitation bubbles through visualization experiments and image processing. We then improved the prediction accuracy of the poppet valve behavior by applying the bubble mixing ratio obtained using the method in the numerical simulation model. The described methods not only avoid the sensor effect on the flow field but also save the additional measurement cost, and they are easy to apply to hydraulics systems

Sperm phenotypic plasticity in a cichlid: a territorial male's counterstrategy to spawning takeover

Studies of sperm competition in species with alternative reproductive tactics (ARTs) often pay attention to the differences in investments in sperm between sneakers facing a higher sperm competition risk and bourgeois males facing a lower risk. Here, we examined within-tactic as well as among-tactic variations in sperm investments in the Lake Tanganyika shell-brooding cichlid Telmatochromis vittatus, a species with 2 types of parasitic tactics. Territorial male T. vittatus suffer reproductive parasitism by both smaller sneaker males and larger pirate males ("pirates” take over the spawning event during which territorial males perform sneaking as a counterstrategy). We hypothesized that both territorial males living under the risk of pirates and sneakers face increased risk of sperm competition and therefore should produce high-quality sperm compared with both territorial males that experienced no piracy risk and pirates. As expected, field studies showed that the former 2 males produced longer lived sperm than the other males. Aquarium experiments demonstrated that a visual stimulus of a pirate was enough to induce an increase in sperm longevity in territorial males compared with when no such stimulus was given. These results indicate that territorial male T. vittatus can plastically adjust at least one sperm quality trait in response to piracy risk. Moreover, long-term monitoring of males in the field showed that small territorial males grow into large territorial males and finally into pirates, so ARTs are not fixed over life. Accordingly, male T. vittatus appear to ontogenetically change their sperm longevity in response to size-dependent sperm competition risk

The First Systematic Survey for Lyman Alpha Emitters at z=7.3 with Red-sensitive Subaru/Suprime-Cam

We have performed deep imaging surveys for LyA emitters (LAEs) at redshift ~7.3 in two blank fields, the Subaru Deep Field (SDF) and the Subaru/XMM-Newton Deep survey Field (SXDF), using the Subaru/Suprime-Cam equipped with new red-sensitive CCDs and a new narrow-band filter, NB1006 (lambda_c=10052 Ang, FWHM=214 Ang). We identified four objects as LAE candidates that exhibit luminosity excess in NB1006. By carrying out deep follow-up spectroscopy for three of them using Subaru/FOCAS and Keck/DEIMOS, a definitively asymmetric emission line is detected for one of them, SXDF-NB1006-2. Assuming this line is LyA, this object is a LAE at z=7.215 which has luminosity of 1.2^{+1.5}_{-0.6} x 10^43 [erg s-1] and a weighted skewness S_w=4.90+-0.86. Another object, SDF-NB1006-2, shows variable photometry and is thus probably a quasar (QSO) or an active galactic nucleus (AGN). It shows an asymmetric emission line at 10076 Ang, which may be due to either LyA at z=7.288 or [OII] at z=1.703. The third object, SDF-NB1006-1, is likely a galaxy with temporal luminosity enhancement associated with a supernova explosion, as the brightness of this object varies between the observed epochs. Its spectrum does not show any emission lines. The inferred decrease in the number density of LAEs toward higher redshift is n_LyA(z=7.3)/n_LyA(z=5.7) = 0.05^+0.11_-0.05 from z=5.7 to 7.3 down to L(LyA)=1.0 x 10^43 [erg s-1]. The present result is consistent with the interpretation in previous studies that the neutral hydrogen fraction is rapidly increasing from z=5.7 to 7.3.Comment: 12 pages, 11 figures, Accepted to Ap

Localised surface plasmon resonance inducing cooperative Jahn–Teller effect for crystal phase-change in a nanocrystal

結晶中の電子の集団的な運動が原子を動かすプラズモン誘起原子変位を初めて発見 --見えない光学センサーなど新技術の実現に期待--. 京都大学プレスリリース. 2023-08-01.The Jahn–Teller effect, a phase transition phenomenon involving the spontaneous breakdown of symmetry in molecules and crystals, causes important physical and chemical changes that affect various fields of science. In this study, we discovered that localised surface plasmon resonance (LSPR) induced the cooperative Jahn–Teller effect in covellite CuS nanocrystals (NCs), causing metastable displacive ion movements. Electron diffraction measurements under photo illumination, ultrafast time-resolved electron diffraction analyses, and theoretical calculations of semiconductive plasmonic CuS NCs showed that metastable displacive ion movements due to the LSPR-induced cooperative Jahn–Teller effect delayed the relaxation of LSPR in the microsecond region. Furthermore, the displacive ion movements caused photo-switching of the conductivity in CuS NC films at room temperature (22 °C), such as in transparent variable resistance infrared sensors. This study pushes the limits of plasmonics from tentative control of collective oscillation to metastable crystal structure manipulation

Subaru FOCAS survey of z=7-7.1 Ly{\alpha} emitters: a test for z >~ 7 Ly{\alpha} photometric luminosity functions

Recent observations of z >~ 7 Ly{\alpha} emitters (LAEs) have derived a variety of Ly{\alpha} luminosity functions (LFs) with contradictory results, evolution or non-evolution from z <~ 6, the epoch after reionization. This could be because most of z >~ 7 LFs comprise photometric candidates and might include some contaminations. We conducted the Subaru Telescope Faint Object Camera And Spectrograph narrowband NB980 ({\lambda}c ~ 9800A, FWHM ~ 100A) imaging and spectroscopy survey of z=7-7.1 LAEs to compare its "contamination-free" result with z >~ 7 photometric Ly{\alpha} LFs previously derived. We imaged the Subaru Deep Field and the sky around a cluster MS 1520.1+3002 and found one LAE candidate, but spectroscopy did not reveal Ly{\alpha} though deep enough to detect it. We calculated the expected number of LAEs in our survey, using five z=7 and three z=7.7 Ly{\alpha} LFs from recent surveys. Seven of them are consistent with null detection (0.1^{+1.8}_{-0.1}-1.1^{+2.2}_{-1.0} LAEs) within errors including Poisson statistics and cosmic variance, but average values (0.7-1.1 LAEs) predicted from one z=7 and two z=7.7 LFs among the seven indicate nearly a single detection. The remaining one z=7 LF predicts 3.0^{+3.2}_{-2.0} LAEs. As to z=7, the discrepancy likely comes from different LAE selection criteria. For z=7.7, there are two possibilities; (1) If z=7.7 LAEs are somehow brighter in Ly{\alpha} luminosity than lower redshift LAEs, z=7.7 LF is observed to be similar to or higher than lower redshift LFs even if attenuated by neutral hydrogen. (2) All/most of the z=7.7 candidates are not LAEs. This supports the decline of LF from z ~ 6 to 7.7 and reionization at z ~ 6-7.7.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society, 2012 March 0

Effect of acute ether or restraint stress on plasma corticotropin-releasing hormone, vasopressin and oxytocin levels in the rat.

Ether and restraint stress-induced peripheral plasma corticotropin releasing hormone (CRH), arginine vasopressin (AVP), oxytocin (OXY) and adrenocorticotropin (ACTH) levels were measured by radioimmunoassays. Plasma CRH, AVP, OXY and ACTH rose to approximately twice the level of control rats 2 min after the onset of a 1-min exposure to ether. Plasma CRH rose further 5 min after the onset of ether stress, while plasma AVP and OXY returned to the baseline levels at 5 min. Plasma CRH, OXY and ACTH showed significant elevation 2 min after the onset of restraint stress, while plasma AVP did not show a significant change. Plasma OXY and ACTH rose further 5 min after the onset of restraint stress, whereas plasma CRH returned to baseline levels. CRH and OXY concentrations in the hypothalamic median eminence decreased 5 min after the onset of ether exposure and restraint, while the AVP concentration did not differ from control levels. The results, including the discrepancy between plasma CRH and ACTH 5 min after stress, suggest that CRH in the peripheral plasma is derived from both hypothalamic and extrahypothalamic tissues. The levels of stress-induced CRH in the peripheral plasma were sufficient to stimulate ACTH release. These results suggest that ether and restraint stress elevate plasma CRH shortly after the onset of the stress, and that this elevation in the plasma CRH level is at least partly responsible for stress-induced ACTH secretion.</p

QUANTITATIVE MEASUREMENT OF TEMPERATURE GRADIENT IN NATURAL HEAT CONVECTION USING COLOR-STRIPE BACKGROUND ORIENTED SCHLIEREN (CSBOS) TECHNIQUE AND COMPUTED TOMOGRAPHY (CT) METHOD

ABSTRACT Quantitative image analysis and measurement of flow fields in convective heat transfer has great importance for the optimum energy consumption problems. In natural and forced convection phenomena of fluids, the complexity of flow field prevents us from detailed three dimensional (3D) experimental analyses of steady/unsteady dynamics in fluids. These flow fields have locally different density and temperature values and yet to be observed quantitatively. Recent development of the Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV) techniques lead us to the quantitative investigation of flow fields in experimental researches. On the other hand, in image measurements density and temperature distributions have been grasped only in two-dimensions (2D). These qualitative image analyses of flow fields were obtained by using classical flow visualizing techniques, such as shadowgraph and color schlieren method. This paper describes the quantitative measurement of convective flow field using our originally proposed color striped background oriented schlieren (CSBOS) method. The obtained measured image data is used for CT reconstruction and 3D temperature gradient distributions