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- Ahmed, M., et al.
(författare)
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Search for the lepton-family-number nonconserving decay μ +→e +γ
- 2002
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Ingår i: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 65:11
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Tidskriftsartikel (refereegranskat)abstract
- The MEGA experiment, which searched for the muon- and electron-number violating decay μ +→e + γ, is described. The spectrometer system, the calibrations, the data taking procedures, the data analysis, and the sensitivity of the experiment are discussed. The most stringent upper limit on the branching ratio, B(μ + →e + γ)<1.2×10 -11 with 90% confidence, is derived from a likelihood analysis.
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| 5. |
- Antoniou, A, et al.
(författare)
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Average risks of breast and ovarian cancer associated with BRCA1 or BRCA2 mutations detected in case series unselected for family history: A combined analysis of 22 studies
- 2003
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Ingår i: American Journal of Human Genetics. - : Elsevier BV. - 0002-9297. ; 72:5, s. 1117-1130
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Tidskriftsartikel (refereegranskat)abstract
- Germline mutations in BRCA1 and BRCA2 confer high risks of breast and ovarian cancer, but the average magnitude of these risks is uncertain and may depend on the context. Estimates based on multiple-case families may be enriched for mutations of higher risk and/or other familial risk factors, whereas risk estimates from studies based on cases unselected for family history have been imprecise. We pooled pedigree data from 22 studies involving 8,139 index case patients unselected for family history with female (86%) or male (2%) breast cancer or epithelial ovarian cancer (12%), 500 of whom had been found to carry a germline mutation in BRCA1 or BRCA2. Breast and ovarian cancer incidence rates for mutation carriers were estimated using a modified segregation analysis, based on the occurrence of these cancers in the relatives of mutation-carrying index case patients. The average cumulative risks in BRCA1-mutation carriers by age 70 years were 65% (95% confidence interval 44%-78%) for breast cancer and 39% (18%-54%) for ovarian cancer. The corresponding estimates for BRCA2 were 45% (31%-56%) and 11% (2.4%-19%). Relative risks of breast cancer declined significantly with age for BRCA1-mutation carriers ( P trend .0012) but not for BRCA2-mutation carriers. Risks in carriers were higher when based on index breast cancer cases diagnosed at <35 years of age. We found some evidence for a reduction in risk in women from earlier birth cohorts and for variation in risk by mutation position for both genes. The pattern of cancer risks was similar to those found in multiple-case families, but their absolute magnitudes were lower, particularly for BRCA2. The variation in risk by age at diagnosis of index case is consistent with the effects of other genes modifying cancer risk in carriers.
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| 8. |
- Kou, Shao Quan, et al.
(författare)
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Numerical investigation of particle breakage as applied to mechanical crushing—Part II: Interparticle breakage
- 2001
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - 1365-1609 .- 1873-4545. ; 38:8, s. 1163-1172
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Tidskriftsartikel (refereegranskat)abstract
- A numerical approach to interparticle breakage is applied using the rock failure process analysis code, RFPA2D. A 2D particle assembly in a container is first numerically simulated to obtain the fringe patterns of stress fields that resemble the photoelastic test. Then, in addition, the interparticle breakage of the particle assembly in a chamber is conducted. The chamber consists of a steel container and a steel platen for transferring the load, and contains 15 particles of arbitrary sizes and irregular shapes. A plane strain condition is assumed. The particle bed is loaded under form conditions, in which the size reduction and the applied force are a function of the displacement. The numerical results indicate that, during the crushing process, three principal regimes appear: (i) the elastic deformation regime, where each particle deforms elastically; (ii) the fragmentation regime, where the particle assembly is crushed in a particle-by-particle fashion; and (iii) the assembly hardening regime, where the densified assembly recovers a significant stiffness. The dominant mode of failure is at first splitting, which is more or less parallel to the loading direction, and then progressive crushing, which mainly depends on the confinement from the chamber walls. The analysis of the load–displacement curves of the assembly obtained from the simulations reveals a high undulating load plateau, which suggests a macro-ductile behaviour.
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| 9. |
- Kou, Shaoquan, et al.
(författare)
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Rock fragmentation mechanisms induced by a drill bit
- 2004
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - : Elsevier BV. - 1365-1609 .- 1873-4545. ; 41:Suppl. 1, s. 527-532
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Tidskriftsartikel (refereegranskat)abstract
- In most of the mechanical excavation methods the fundamental process is indentation of the rock by a bit. The present paper focuses on discussing how the rock is fragmented under the action of a drill bit. The discussions are mainly based on numerical modelling using the rock and tool interaction code (R-T2D) and taking rock heterogeneity into consideration. The simulated results concerning rock penetrations with one, two and multiple indenters are, however, compared with experiments available from the literature. The emphasis is put on discussion of the formation of side-cracks and crushed zones that constitute the major rock removal fractures. The agreement between numerical simulation and experimental observations are reasonably good. This reveals the mechanisms of crack initiation, propagation and coalescence induced by the action of button bits to form the rock fragmentation in a drilling process. The investigation can contribute not only to improving percussive drilling but also to understanding other rock fragmentation and comminution methods and equipment since indentation is also the fundamental process for them.
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