The Identification of rDNA-ITS and Localization of heterochronic gene In Meloidogyne javanica

根结线虫是重要的植物内寄生线虫。本论文以同安农田采集的番茄病根中爪哇根结线虫为实验材料，对病根进行解剖，收集成虫、二期幼虫和卵块。通过对根结线虫胚胎发育和生活史中各期虫体形态的观察，进一步定种为爪哇根结线虫。通过感染室内土培番茄，使得爪哇根结线虫在实验室得到进一步的扩大培养，为后续实验的进行提供了材料。利用rRNA基因间隔序列的保守性引物对来自不同宿主的爪哇根结线虫和南方根结线虫的rDNA-ITS1和rDNA-ITS2序列进行了扩增，与Genebank中根结线虫的ITS1序列在clustalX软件中进行了分析，构建系统发生树和遗传距离矩阵。分析可知，来源于番茄根内和蒲公英根内的爪哇根结线虫rD...Root-knot nematodes are important endo-parasites in economic plants. The roots of tomatoes infected with M. javanica were got from the field of Tong’an rural area and roots were dissected.The egg masses, pre-parasitic juveniles and female adults of M. javanica were collected in the lab.The embryo development and different stages of life cycle of root-knot nematode were observed. In order to obtain...学位：理学硕士院系专业：生命科学学院生物学系_动物学学号：20032601

Light meson spectroscopy from Dalitz plot analyses ηc decays to η0K + K − , η0π + π − , and ηπ + π − produced in two-photon interactions

We study the processes γγ → ηc → η0KþK−, η0πþπ−, and ηπþπ− using a data sample of 519 fb−1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at and near the Υ(nS) (n = 2, 3, 4) resonances. This is the first observation of the decay ηc → η0KþK− and we measure the branching fraction Γðηc → η0KþK−Þ=ðΓðηc → η0πþπ−Þ 1⁄4 0.644 0.039stat 0.032sys. Significant interference is observed between γγ → ηc → ηπþπ− and the nonresonant two-photon process γγ → ηπþπ−. A Dalitz plot analysis is performed of ηc decays to η0KþK−, η0πþπ−, and ηπþπ−. Combined with our previous analysis of ηc → KK ̄ π, we measure the K 0ð1430Þ parameters and the ratio between its η0K and πK couplings. The decay ηc → η0πþπ− is dominated by the f0ð2100Þ resonance, also observed in J=ψ radiative decays. A new a0(1700)→ ηπ resonance is observed in the ηc → ηπþπ− channel. We also compare ηc decays to η and η0 final states in association with scalar mesons as they relate to the identification of the scalar glueball

Performance of the front end electronics and data acquisition system for the SLD Cherenkov Ring Imaging Detector

The front end electronics and data acquisition system for the SLD barrel Cherenkov Ring Imaging Detector (CRID) are described. This electronics must provide a 1% charge division measurement with a maximum acceptable noise level of 2000 electrons (rms). Noise and system performance results are presented for the initial SLD engineering run data

Photon detectors

J. Seguinot and T. Ypsilantis have recently described the theory and history of Ring Imaging Cherenkov (RICH) detectors. In this paper, I will expand on these excellent review papers, by covering the various photon detector designs in greater detail, and by including discussion of mistakes made, and detector problems encountered, along the way. Photon detectors are among the most difficult devices used in physics experiments, because they must achieve high efficiency for photon transport and for the detection of single photo-electrons. For gaseous devices, this requires the correct choice of gas gain in order to prevent breakdown and wire aging, together with the use of low noise electronics having the maximum possible amplification. In addition, the detector must be constructed of materials which resist corrosion due to photosensitive materials such as, the detector enclosure must be tightly sealed in order to prevent oxygen leaks, etc. The most critical step is the selection of the photocathode material. Typically, a choice must be made between a solid (CsI) or gaseous photocathode (TMAE, TEA). A conservative approach favors a gaseous photocathode, since it is continuously being replaced by flushing, and permits the photon detectors to be easily serviced (the air sensitive photocathode can be removed at any time). In addition, it can be argued that we now know how to handle TMAE, which, as is generally accepted, is the best photocathode material available as far as quantum efficiency is concerned. However, it is a very fragile molecule, and therefore its use may result in relatively fast wire aging. A possible alternative is TEA, which, in the early days, was rejected because it requires expensive CaF{sub 2} windows, which could be contaminated easily in the region of 8.3 eV and thus lose their UV transmission

Initial performance of the SLD Cherenkov Ring Imaging Detector system

All of the major subsystems for the barrel Cherenkov Ring Imaging Detector (CRID) in the SLD at SLAC have now been commissioned. The CRID participated in the SLD engineering run of June--August 1991. In a cosmic ray test at the end of the run, Cherenkov rings were observed for the first time. Initial data from the CRID, including Cherenkov rings, studies of minimum ionizing particles, and data from the fiber optics calibration system are presented here

Search for the rare decays B→πl+l− and B0→ηl+l−

We present the results of a search for the rare flavor-changing neutral-current decays B→πl+l− (π=π±, π0 and l=e, μ) and B0→ηl+l− using a sample of e+e−→Υ(4S)→BB⎯⎯⎯ decays corresponding to 428 fb−1 of integrated luminosity collected by the BABAR detector. No significant signal is observed, and we set an upper limit on the isospin and lepton-flavor averaged branching fraction of B(B→πl+l−)<5.9×10−8 and a lepton-flavor averaged upper limit of B(B0→ηl+l−)<6.4×10−8, both at the 90% confidence level. We also report 90% confidence level branching fraction upper limits for the individual modes B+→π+e+e−, B0→π0e+e−, B+→π+μ+μ−, B0→π0μ+μ−, B0→ηe+e−, and B0→ημ+μ−