Browsing by Author "Chou, Yu-Ting"

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Effects of residue background events in direct dark matter detection experiments on the determination of the WIMP mass
(2010-08-01)
Chou, Yu-Ting
;
Shan, Chung-Lin
;
物理研究所
;
Institute of Physics
In the earlier work on the development of a model- independent data analysis method for determining the mass of Weakly Interacting Massive Particles (WIMPs) by using measured recoil energies from direct Dark Matter detection experiments directly, it was assumed that the analyzed data sets are background- free, i. e., all events are WIMP signals. In this article, as a more realistic study, we take into account a fraction of possible residue background events, which pass all discrimination criteria and then mix with other real WIMP-induced events in our data sets. Our simulations show that, for the determination of the WIMP mass, the maximal acceptable fraction of residue background events in the analyzed data sets of O(50) total events is similar to 20%, for background windows of the entire experimental possible energy ranges, or in low energy ranges; while, for background windows in relatively higher energy ranges, this maximal acceptable fraction of residue background events can not be larger than similar to 10%. For a WIMP mass of 100 GeV with 20% background events in the windows of the entire experimental possible energy ranges, the reconstructed WIMP mass and the 1 sigma statistical uncertainty are similar to 97 GeV +61%-35% (similar to 94 GeV +55%-33% for background- free data sets).
Identification of a noncanonical function for ribose-5-phosphate isomerase A promotes colorectal cancer formation by stabilizing and activating beta-catenin via a novel C-terminal domain
(2018-01-01)
Chou, Yu-Ting
;
Jiang, Jeng-Kai
;
Yang, Muh-Hwa
;
Lu, Jeng-Wei
;
Lin, Hua-Kuo
Altered metabolism is one of the hallmarks of cancers. Deregulation of ribose-5-phosphate isomerase A (RPIA) in the pentose phosphate pathway (PPP) is known to promote tumorigenesis in liver, lung, and breast tissues. Yet, the molecular mechanism of RPIA-mediated colorectal cancer (CRC) is unknown. Our study demonstrates a noncanonical function of RPIA in CRC. Data from the mRNAs of 80 patients' CRC tissues and paired nontumor tissues and protein levels, as well as a CRC tissue array, indicate RPIA is significantly elevated in CRC. RPIA modulates cell proliferation and oncogenicity via activation of beta-catenin in colon cancer cell lines. Unlike its role in PPP in which RPIA functions within the cytosol, RPIA enters the nucleus to form a complex with the adenomatous polyposis coli (APC) and beta-catenin. This association protects beta-catenin by preventing its phosphorylation, ubiquitination, and subsequent degradation. The C-terminus of RPIA (amino acids 290 to 311), a region distinct from its enzymatic domain, is necessary for RPIA-mediated tumorigenesis. Consistent with results in vitro, RPIA increases the expression of beta-catenin and its target genes, and induces tumorigenesis in gut-specific promotor-carrying RPIA transgenic zebrafish. Together, we demonstrate a novel function of RPIA in CRC formation in which RPIA enters the nucleus and stabilizes beta-catenin activity and suggests that RPIA might be a biomarker for targeted therapy and prognosis.
RF Characteristics of AlGaN/GaN HEMTs under Different Temperatures
(2012-01-01)
Chiu, Yu-Sheng
;
Huang, Jui-Chien
;
Lin, Tai-Ming
;
Chou, Yu-Ting
;
Lu, Chung-Yu
We present the Rf characteristics of 0.7-mu m gate length n-GaN/AlGaN/GaN high-electron mobility transistors (HEMTs) with different source-drain spacing tested under different temperatures.. The 7-mu m source-drain spacing device demonstrated 800 mA/mm drain current density and 257 mS/mm tranceconductance, and the 5-mu m source-drain spacing device demonstrated 700 mA/mm drain current density and 260 mS/mm tranconductance. The 7-mu m source-drain spacing device was measured at room temperatures of 25 degrees C and -40 degrees C, the current gain (f(T)) were 18 GHz and 21GHz and the maximum oscillation (f(max)(U)) frequency were 63 GHz-and 87 GHz, respectively The f(T) was nearly linearly dependent on the temperature. As operating temperature increased from -40 degrees C to 50 degrees C, the f(T) dropped more dramatically for the 5-mu m SD spacing device than for the 7-mu m device. The f(max) characteristic of 5-mu m SD spacing device decreases more dramatically above 125 degrees C than the 7-mu m SD spacing device. This phenomenon might be due to stronger phonon scattering for shorter channel device at high temperatures.
Ribose-5-phosphate isomerase A overexpression promotes liver cancer development in transgenic zebrafish via activation of ERK and beta-catenin pathways
(2019-03-01)
Chou, Yu-Ting
;
Chen, Li-Yang
;
Tsai, Shin-Lin
;
Tu, Hsiao-Chen
;
Lu, Jeng-Wei
Dysregulation of the enzymes involved in the pentose phosphate pathway (PPP) is known to promote tumorigenesis. Our recent study demonstrated that ribose-5-phosphate isomerase (RPIA), a key regulator of the PPP, regulates hepatoma cell proliferation and colony formation. Our studies in zebrafish reveal that RPIA-mediated hepatocarcinogenesis requires extracellular signal-regulated kinase (ERK) and beta-catenin signaling. To further investigate RPIA-mediated hepatocarcinogenesis, two independent lines of transgenic zebrafish expressing human RPIA in the liver were generated. These studies reveal that RPIA overexpression triggers lipogenic factor/enzyme expression, steatosis, fibrosis and proliferation of the liver. In addition, the severity of fibrosis and the extent of proliferation are positively correlated with RPIA expression levels. Furthermore, RPIA-mediated induction of hepatocellular carcinoma (HCC) requires the ERK and beta-catenin signaling pathway but is not dependent upon transaldolase levels. Our study presents a mechanism for RPIA-mediated hepatocarcinogenesis and suggests that RPIA represents a valuable therapeutic target for the treatment of HCC.