Low-Temperature Phase Transition near V_3H_2

Heat capacity measurements have been made on the V-H alloys with the compositions VH_ to VH_ in the temperature range from -140 to 50℃. Anomalous heat absorptions are observed at -100 to -50℃ depending on composition, indicating the occurrence of a phase transition attributed to the hydrogen ordering. A model of the superstructure of V_3H_2 is proposed for the low-temperature form on the basis of electron diffraction work by Wanagel et al

Measuring the brightness temperature distribution of extragalactic radio sources with space VLBI

We have used VSOP space very long baseline interferometry observations to measure the brightness temperature distribution of a well-defined sub-set of the Pearson-Readhead sample of extragalactic radio sources. VLBI which is restricted to Earth-diameter baselines is not generally sensitive to emitting regions with brightness temperatures greater than approximately $10^{12}$ K, coincidentally close to theoretical estimates of brightness temperature limits, $10^{11} - 10^{12}$ K. We find that a significant proportion of our sample have brightness temperatures greater than $10^{12}$ K; many have unresolved components on the longest baselines, and some remain completely unresolved. These observations begin to bridge the gap between the extended jets seen with ground-based VLBI and the microarcsecond structures inferred from intraday variability, evidenced here by the discovery of a relationship between intraday variability and VSOP-measured brightness temperature, likely due to the effects of relativistic beaming. Also, lower limits on jet Lorentz factors, estimated from space VLBI observations, are starting to challenge numerical simulations that predict low Lorentz factor jets.Comment: 4 pages + 1 figure, ApJ letters, accepte

Multiple aster formation is frequently observed in bovine oocytes retrieved from 1 day-stored ovaries

We have recently reported that multiple aster formation after IVF was one of the factors negatively affecting to developmental competence of vitrified-warmed bovine matured oocytes, and that a short-term culture of the post-warm oocytes with an inhibitor of Rho-associated coiled-coil kinase (ROCK) suppressed the multiple aster formation and improved the blastocyst yield. The present study was conducted to investigate whether increased multiple aster formation following IVF can be involved in impaired developmental competence of stored ovary-derived bovine oocytes. Oocytes retrieved from 1-day stored ovaries had lower developmental potential to Day 8 blastocysts when compared with those from fresh ovaries (37 vs 63%). Immunostaining against -tubulin 10 h post-IVF revealed that the higher incidence of multiple aster formation occurred in oocytes retrieved from stored ovaries than fresh ovaries (31 vs 15%). Treatment of post-IVM oocytes with ROCK inhibitor for 2 h significantly suppressed the incidence of multiple aster formation (10 vs 32% in control group). However, the suppressing effect of ROCK inhibitor on multiple aster formation in IVM/IVF oocytes did not improve blastocyst yield from stored ovary-derived oocytes (41 vs 37% in control group). These results suggest that higher incidence of multiple aster formation by bovine ovary storage was not responsible for decreased developmental competence of IVF oocytes.ArticleZYGOTE.24(1):115-120(2015)journal articl

A combined treatment of ionomycin with ethanol improves blastocyst development of bovine oocytes harvested from stored ovaries and microinjected with spermatozoa

Regardless of the presence of sperm-borne oocyte-activating factors, activation of bovine oocytes with exogenous activation stimuli is required for further development after intracytoplasmic sperm injection (ICSI). The current study was designed to develop a new activation regimen for improving the blastocyst yield after ICSI of bovine oocytes harvested from ovaries stored at 10 to 12 degrees C for 24 h. After ICSI, oocytes were treated with 5 mu M ionomycin for 5 min, 7% ethanol for 5 or 10 min, ionomycin followed by ethanol (5 or 10 min), ionomycin followed by 10 mu g/mL cycloheximide for 5 h, or ionomycin followed by 1.9 mM 6-dimethylaminopurine for 3 h. Across the activation regimens, the cleavage rates of ICSI oocytes (45% to 77%) were higher than those of parthenogenetically activated oocytes (11% to 21%; P 0.05). Higher blastocyst yields were due to increasing the proportion of ICSI oocytes that passed through the early postfertilization events until cleavage. None of the regimens have any adverse effect on the quality of the blastocysts regarding the total cell number or the proportion of the inner cell mass cells. Thus, a new activation regimen using two triggers for single calcium increase effectively improved blastocyst yield after bovine ICSI using oocytes harvested from stored ovaries.ArticleTHERIOGENOLOGY. 72(4):453-460 (2009)journal articl

Live rats resulting from injection of oocytes with spermatozoa freeze-dried and stored for one year

ArticleMolecular Reproduction and Development. 75(5): 890-894 (2008)journal articl

Dual-Frequency VSOP Observations of AO 0235+164

AO 0235+164 is a very compact, flat spectrum radio source identified as a BL Lac object at a redshift of z=0.94. It is one of the most violently variable extragalactic objects at both optical and radio wavelengths. The radio structure of the source revealed by various ground-based VLBI observations is dominated by a nearly unresolved compact component at almost all available frequencies. Dual-frequency space VLBI observations of AO 0235+164 were made with the VSOP mission in January-February 1999. The array of the Japanese HALCA satellite and co-observing ground radio telescopes in Australia, Japan, China and South Africa allowed us to study AO 0235+164 with an unprecedented angular resolution at frequencies of 1.6 and 5 GHz. We report on the sub-milliarcsecond structural properties of the source. The 5-GHz observations led to an estimate of T_B > 5.8 x 10^{13} K for the rest-frame brightness temperature of the core, which is the highest value measured with VSOP to date.Comment: 8 pages, 8 figures, to appear in Publ. Astron. Soc. Japa