Transverse momentum dependence of Hanbury Brown-Twiss radii of pions from a perfectly opaque source with hydrodynamic flow

We investigate the transverse momentum dependence of pion HBT radii on the basis of a hydrodynamical model. Recent experimental data show that $R_{\text{out}}/R_{\text{side}} < 1$, which suggests a strong opaqueness of the source. In addition to the opaqueness naturally caused by transverse flow, we introduce an extrinsic opacity by imposing restrictions on the pion emission angle. Comparing the HBT radii obtained from the normal Cooper-Frye prescription and the opaque emission prescription, we find that $R_{\text{out}}/R_{\text{side}}$ is less than unity only for small values of the transverse momentum with an opaque source. However, HBT radii for large values of the transverse momentum are dominated by the transverse flow effect and are affected less by the source opaqueness.Comment: 9 pages, 7 figures. 2 figures are added. To be published in Prog. Theor. Phy

HBT Effect Based on a Hydrodynamical Model

We investigate HBT radii based on the numerical solutions of the hydrodynamical model which are so tuned as to reproduce the recent experimental data at the CERN SPS. Comparing the sizes of freeze-out hypersurface with HBT radii, we discuss dynamical effect of the systematic flow on the apparent HBT radii. Finally we compare HBT radii of the QGP phase transition model with those of the hadron gas model without phase transition.Comment: 5 pages, LaTeX, 7 EPS figures. Talk at the International School on the Physics of Quark Gluon Plasma, June 3-6, 1997, Hiroshima, Japa

Two-particle correlation from a relativistic fluid with a first order phase transition

We numerically calculate two-particle correlation functions of CERN-SPS 158 A GeV Pb+Pb central collisions based on a (3+1)-dimensional relativistic hydrodynamics with a first order phase transition. We analyze the pair momentum dependence of pion source sizes extracted from the Yano-Koonin-Podgoretski\u{\i} (YKP) parametrization which is expected to give the source sizes directly. We find that, even in the case of the first order phase transition, the collective expansion and surface dominant freeze-out of the fluid naturally lead to the opaque source for which the interpretation of the temporal source parameter as the emission duration breaks down.Comment: LaTeX, 4pages, 2 figures. To appear in the Proceedings of the International Conference on Quark Nuclear Physics, Adelaide, Australia, 21-25 February, 200

Fundamental Study of Cold Heat-Storage and Heat-Release Systems of Fine Capsulated Latent Heat-Storage Material-Water Mixture : 2nd Report, Flow and Cold Heat-Storage Characteristics of Fine Capsulated Latent Heat-Storage Material-Water Mixture in a Coiled Double-Tube Heat Exchanger

The physical properties of the test fine capsulated latent heat-storage material-water mixture were described in the first report. This paper deals with flow and cold heat-storage characteristics of the fine capsulated latent heat-storage material-water mixture as a latent heat-storage material having a low melting point of the core material (pentadecane, C_H_, freezing point 283.1 K). A coiled double-tube heat exchanger was used for the cold heat-storage experiment. The pressure drop, the heat-transfer coefficient and the finishing time of cold heat-storage in the coiled tube were measured as experimental parameters. It was clarified that the flow behavior of the fine capsulated latent heat-storage material-water mixture as a non-Newtonian fluid played an important role in cold heat-storage. The nondimensional correlation equations for the additional pressure loss coefficient, the heat-transfer coefficient and the finishing time of the cold heat-storage were derived in terms of Dean number and heat capacity ratio.微細な低温潜熱物質を水中に混合した材料を用いる蓄冷熱輸送システムは、熱交換器内で微細な潜熱物質の運動のもたらす熱伝達促進効果による熱交換効率の向上、および水の顕熱に潜熱を上乗せすることによる輸送熱量の増大により、管径寸法の縮小が期待できる。このような低温潜熱物質の混合水を用いた蓄熱システムは、従来の冷熱輸送媒体として用いられてきた水（顕熱）に代わる有効な潜熱蓄冷熱システムの一つと考えられる。低温潜熱エネルギの蓄冷熱および搬送システムに関する研究としては、潜熱材料としてクラスレート、氷および雪スラリーなどを用いたものがある。これらの潜熱材料を用いた場合、水との密度差により低流速域において均一混合流が得にくいことや、粒子同士の結合により粒子魂を形成するなどの問題を有する。水中に分散質としての潜熱蓄冷熱材料を微細化混合するOil/Water型エマルションは、搬送管内における粒子魂形成を防止し、管内においても安定した均質混合流が得られる。しかし、Oil/Water型エマルションは、潜熱体の微細化混合に界面活性剤が用いられるために、その粘性が大きく管内の圧力損失が大きくなる欠点を有する。潜熱蓄冷熱材料を微細なカプセル化して水と混合する方法は、粒子魂の形成を防止することが可能であり、連続相を水のみとすることにより、管内搬送圧力損失を比較的小さくすることが可能である。このため、本研究においては、管内において均質な混合と良好な流動状態が得られるような十分微細なカプセル化潜熱物質の混合水を用いた潜熱蓄冷熱実験を行った。この種の微細なカプセル化潜熱物質の混合水は、連続相としての水中に微細カプセルが分散している複雑な系を有し、さらに、非ニュートン挙動を示すなどの取り扱いの難しさ、そして安定性の問題などが原因となり、その蓄冷熱特性および流動特性に関する研究はほとんど行われていない現状にある。すでに、著者らは、第1報において低温潜熱冷物質（ペンタデカン、C15H32、融点Tf=293.1K、潜熱L=158kj/kg）を芯物質とした微細カプセル潜熱物質の混合水の熱物性評価、そして、輸送特性において重要となる粘性評価を行っており、この種の微細なカプセル潜熱物質の混合水に関する物性の特色を把握している。本研究は、微細カプセル潜熱物質の混合水に関する伝熱および流動特性を基礎的に検討する目的より、比較的構造の簡単な一種類のコイル状2重管式熱交換器を対象とし、微細なカプセル潜熱物質の混合水の初期温度、微細カプセルの質量割合、微細カプセル混合水の管内平均流速などを因子とした実験を行った。すなわち、微細カプセル混合水のコイル状管内の流動抵抗、熱伝達率、そして液相から固相への相変化時間に関する測定とこれらの無次元整理式の提案を行うものである

Expression of secretory calcium-binding phosphoprotein (scpp) genes in medaka during the formation and replacement of pharyngeal teeth

Background Analyses of tooth families and tooth-forming units in medaka with regard to tooth replacement cycles and the localization of odontogenic stem cell niches in the pharyngeal dentition clearly indicate that continuous tooth replacement is maintained. The secretory calcium-binding phosphoprotein (scpp) gene cluster is involved in the formation of mineralized tissues, such as dental and bone tissues, and the genes encoding multiple SCPPs are conserved in fish, amphibians, reptiles, and mammals. In the present study, we examined the expression patterns of several scpp genes in the pharyngeal teeth of medaka to elucidate their roles during tooth formation and replacement. Methods Himedaka (Japanese medaka, Oryzias latipes) of both sexes (body length: 28 to 33 mm) were used in this study. Real-time quantitative reverse transcription-polymerase chain reaction (PCR) (qPCR) data were evaluated using one-way analysis of variance for multi-group comparisons, and the significance of differences was determined by Tukey’s comparison test. The expression of scpp genes was examined using in situ hybridization (ISH) with a digoxigenin-labeled, single-stranded antisense probe. Results qPCR results showed that several scpp genes were strongly expressed in pharyngeal tissues. ISH analysis revealed specific expression of scpp1, scpp5, and sparc in tooth germ, and scpp5 was continually expressed in the odontoblasts of teeth attached to pedicles, but not in the osteoblasts of pedicles. In addition, many scpp genes were expressed in inner dental epithelium (ide), but not in odontoblasts, and scpp2 consistently showed epithelial-specific expression in the functional teeth. Taken together, these data indicate that specific expression of scpp2 and scpp5 may play a critical role in pharyngeal tooth formation in medaka. Conclusion We characterized changes in the expression patterns of scpp genes in medaka during the formation and replacement of pharyngeal teeth

Nucleotide sequence of a cDNA encoding a common precursor of disintegrin flavostatin and hemorrhagic factor HR2a from the venom of Trimeresurus flavoviridis

AbstractThe venom of Trimeresurus flavoviridis has three disintegrins that act as platelet aggregation inhibitors by binding to integrin αIIbβ3 on platelets through its Arg-Gly-Asp sequence. We isolated the cDNA encoding the flavostatin precursor that is one of the disintegrins in T. flavoviridis venom. The open reading frame consisted of four regions, a pre-peptide region, a metalloprotease region, a spacer region and a disintegrin region, indicating that the flavostatin precursor belongs to the metalloprotease/disintegrin family. Surprisingly, the deduced amino acid sequence of the metalloprotease region was completely consistent with that of hemorrhagic metalloprotease HR2a, which indicated that this metalloprotease released from the flavostatin precursor functions as a hemorrhagic factor. These observations indicated that a disintegrin and a hemorrhagic metalloprotease were synthesized as a common precursor. Thus, our results support the hypothesis that a disintegrin is synthesized as a metalloprotease/disintegrin precursor and matures by cleavage from the precursor molecule