A test facility to study the light-transmission properties of scintillating fiber waveguides for tracking applications in high-energy physics is being developed. A light-tight box 2 m in length has ...been built, and data acquisition hardware and software is in place for testing various aspects of scintillating fibers and waveguides. Scintillating fibers have been excited with radioactive sources, ultraviolet light sources, and light-emitting diodes. Various photodetectors such as photomultiplier tubes, photodiodes, charge-coupled devices and solid-state photomultipliers have been utilized to detect the transmitted light. Studies of attenuation length and transmission through splices are presented.< >
Although microRNAs (miRs) have been implicated in the pathogenesis of various human malignancies, limited information is available regarding mechanisms by which these noncoding RNAs contribute to ...initiation and progression of tobacco-induced esophageal cancers. In this study, array and quantitative reverse transcriptase-PCR techniques were used to examine miR expression in immortalized esophageal epithelia (IEE) and esophageal adenocarcinoma (EAC) cells cultured in normal media with or without cigarette smoke condensate (CSC). Under relevant exposure conditions, CSC significantly decreased miR-217 expression in these cells. Endogenous levels of miR-217 expression in cultured EAC cells (EACC)/primary EACs were significantly lower than those observed in IEE/ paired normal esophageal tissues. RNA crosslink immunoprecipitation, quantitative reverse transcriptase-PCR (qRT-PCR) and immunoblot experiments demonstrated direct interaction of miR-217 with kallikrein 7 (KLK7), encoding a putative oncogene not previously implicated in EAC. Repression of miR-217 correlated with increased levels of KLK7 in primary EACs, particularly those from smokers. Chromatin and methylated DNA immunoprecipitation experiments demonstrated that CSC-mediated repression of miR-217 coincided with DNMT3b-dependent hypermethylation and decreased occupancy of nuclear factor 1 within the miR-217 genomic locus. Deoxyazacytidine induced miR-217 expression and downregulated KLK7 in EACC; deoxyazacytidine also attenuated CSC-mediated miR-217 repression and upregulation of KLK7 in IEE and EACC. Overexpression of miR-217 significantly decreased, whereas overexpression of KLK7 increased proliferation, invasion and tumorigenicity of EACC. Collectively, these data demonstrate that epigenetic repression of miR-217 contributes to the pathogenesis of EAC via upregulation of KLK7 and suggest that restoration of miR-217 expression may be a novel treatment strategy for these malignancies.
Scintillating fiber tracking detectors are being developed for the SDC experiment at Superconducting Super Collider (SSC) and the upgrade of the D0 detector at the Fermilab Tevatron. The many ...attractive features of a fiber tracker include good position resolution, low occupancy, low mass in the active volume, and excellent resistance to radiation damage. An additional important feature, especially at the SSC, is the intrinsically prompt response time of a scintillating fiber. The photodetector of choice is the visible light phonon counter (VLPC), a device which combines high rate capability with high quantum efficiency at visible wavelengths. To realize the high rate capability of the VLPC requires the implementation of a suitable, fast preamplifier. Until recently, studies of fibers and VLPCs with radioactive sources and cosmic rays have been performed under low rate conditions using transimpedance amplifiers (TIAs). The authors report on the response characteristics of a fiber-VLPC system coupled to a variety of fast preamplifiers, including QPA02, VTX, and TVC devices. Their performance is compared with that of a transimpedance amplifier.< >
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