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- Szymanski, J. J., et al.
(författare)
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A study of the decay mu –> e gamma by the MEGA experiment
- 1996
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Ingår i: Proceedings, 9th Meeting, DPF'96, Minneapolis, USA, August 11-15, 1996. Vol. 1, 2.. ; , s. 1450-1452
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Konferensbidrag (refereegranskat)
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| 4. |
- Cooper, M. D., et al.
(författare)
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Construction and performance of MEGA's low-mass, high-rate cylindrical MWPCs
- 1998
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 417:1, s. 24-49
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Tidskriftsartikel (refereegranskat)abstract
- A design for extremely low mass, high-resolution multiwire proportional chambers (MWPC) was achieved by the MEGA collaboration in its experiment to search for the lepton family number violating decay μ → eγ. To extend the present branching ratio limit by over an order of magnitude, these MWPCs were operated in high particle fluxes. They showed minimal effects of aging, and evidenced spatial and energy resolutions for the orbiting positrons from muon decay which were consistent with our design parameters. The unique features of these chambers, their assembly into the MEGA positron spectrometer, and their performance during the experiment are described in this paper.
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| 8. |
- Yuan, XiMing, et al.
(författare)
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The establishment of two cell lines from a mouse uterine cervical carcinoma (U14) and their metastatic phenotype changes
- 1995
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Ingår i: Clinical and Experimental Metastasis. - 0262-0898 .- 1573-7276. ; 13:6, s. 463-73
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Tidskriftsartikel (refereegranskat)abstract
- This paper studies the heterogeneity of metastatic potential of murine cervical carcinoma (U14). Two cell lines, P11-90 and L10-90, were established from a pulmonary metastatic substrain (U14AP11) and a lymphatic metastatic substrain (U14AL10), which were selected from U14 in vivo after 11 and 10 passages, respectively. The biologic differences between the two cell lines are as follows. (1) The cells of the P11-90 line grow more rapidly compared with the L10-90 line. From the 40th passage the medium pH was different. (2) The median number of chromosomes in P11-90 and L10-90 was 72 and 64, respectively; the rates of gap aberration were 88% and 78%, respectively. (3) The number of T lymphocytes and T helper lymphocytes in the peripheral blood from hosts with P11-90 were higher than that of hosts transplanted with L10-90, but the number of B lymphocytes in the latter was larger than that in the former. (4) The metastatic potential of each cell line partially decreased compared to the relative tumor substrain, but their organ preference still remained and the transplant locations, axillary or footpad, had a prominent influence on their metastatic behavior. To observe the effects of metastatic target organs on the metastatic phenotypes of tumor cells, as well as to explore a method for the establishment and maintenance of the metastatic organ preference of tumor cells, conditioned medium (CM) from pulmonary or lymphatic node diploid cells was added to the culture medium of P11-90 and L10-90. Two sublines, P + P11-90 and Ln + L10-90, were thus established. Using stereological methods we found that the majority of P + P11-90 cells became larger and their nuclei also increased in size compared with their parental lines, but the majority of Ln + L10-90 cells became smaller in size, though the nuclei were enlarged. The pulmonary metastatic rate and lymphatic metastatic rate of P + P11-90, as well as the lymphatic metastatic rate of Ln + L10-90, were restored dramatically. The results suggest that by taking advantage of the interaction between tumor cells and the CM of host cells the metastatic potential of tumor cell lines can be maintained in vitro. Our work may offer an experimental model for the manipulation of metastasis of cell lines coming from the same parent strain but with different metastatic potentials.(ABSTRACT TRUNCATED AT 400 WORDS)
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| 9. |
- Zhang, Z. X., et al.
(författare)
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Effects of loading rate on rock fracture
- 1999
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - 1365-1609 .- 1873-4545. ; 36:5, s. 597-611
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Tidskriftsartikel (refereegranskat)abstract
- By means of a wedge loading applied to a short-rod rock fracture specimen tested with the MTS 810 or SHPB (split Hopkinson pressure bar), the fracture toughness of Fangshan gabbro and Fangshan marble was measured over a wide range of loading rates, =10−2–106 MPa m1/2 s−1. In order to determine the dynamic fracture toughness of the rock as exactly as possible, the dynamic Moiré method and strain–gauge method were used in determining the critical time of dynamic fracture. The testing results indicated that the critical time was generally shorter than the transmitted wave peak time, and the differences between the two times had a weak increasing tendency with loading rates. The experimental results for rock fracture showed that the static fracture toughness KIc of the rock was nearly a constant, but the dynamic fracture toughness KId of the rock (≥104 MPa m1/2 s−1) increased with the loading rate, i.e. log(KId)=a log +b. Macroobservations for fractured rock specimens indicated that, in the section (which was perpendicular to the fracture surface) of a specimen loaded by a dynamic load, there was clear crack branching or bifurcation, and the higher the loading rate was, the more branching cracks occurred. Furthermore, at very high loading rates (≥106 MPa m1/2 s−1) the rock specimen was broken into several fragments rather than only two halves. However, for a statically fractured specimen there was hardly any crack branching. Finally, some applications of this investigation in engineering practice are discussed.
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