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Search Results: 1 - 10 of 124294 matches for " Wei-Ting Chen "
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Density-Dependent Response of an Ultracold Plasma to Few-Cycle Radio-Frequency Pulses
Truman Wilson,Wei-Ting Chen,Jacob Roberts
Physics , 2012, DOI: 10.1103/PhysRevA.87.013410
Abstract: Ultracold neutral plasmas exhibit a density-dependent resonant response to applied radio-frequency (RF) fields in the frequency range of several MHz to hundreds of MHz for achievable densities. We have conducted measurements where short bursts of RF were applied to these plasmas, with pulse durations as short as two cycles. We still observed a density-dependent resonant response to these short pulses. However, the too rapid timescale of the response, the dependence of the response on the sign of the driving field, the response as the number of pulses was increased, and the difference in plasma response to radial and axially applied RF fields are inconsistent with the plasma response being due to local resonant heating of electrons in the plasma. Instead, our results are consistent with rapid energy transfer from collective motion of the entire electron cloud to electrons in high-energy orbits. In addition to providing a potentially more robust way to measure ultracold neutral plasma densities, these measurements demonstrate the importance of collective motion in the energy transport in these systems.
Cosmological and Solar-System Tests of f(R) Modified Gravity
Wei-Ting Lin,Je-An Gu,Pisin Chen
Physics , 2010, DOI: 10.1142/S0218271811019530
Abstract: We investigate the cosmological and the local tests of the f(R) theory of modified gravity via the observations of (1) the cosmic expansion and (2) the cosmic structures and via (3) the solar-system experiments. To fit the possible cosmic expansion histories under consideration, for each of them we reconstruct f(R), known as "designer f(R)". We then test the designer f(R) via the cosmic-structure constraints on the metric perturbation ratio Psi/Phi and the effective gravitational coupling G_eff and via the solar-system constraints on the Brans-Dicke theory with the chameleon mechanism. We find that among the designer f(R) models specified by the CPL effective equation of state w_eff, only the model closely mimicking general relativity with a cosmological constant (LambdaCDM) can survive all the tests. Accordingly, these tests rule out the frequently studied "w_eff = -1" designer f(R) models which are distinct in cosmic structures from LambdaCDM. When considering only the cosmological tests, we find that the surviving designer f(R) models, although exist for a variety of w_eff, entail fine-tuning.
Influence of Electron Evaporative Cooling on Ultracold Plasma Expansion
Truman Wilson,Wei-Ting Chen,Jacob Roberts
Physics , 2013, DOI: 10.1063/1.4813248
Abstract: The expansion of ultracold neutral plasmas (UCP) is driven primarily by the thermal pressure of the electron component and is therefore sensitive to the electron temperature. At lower densities (less than 10$^8$ /cm$^3$), evaporative cooling has a significant influence on the UCP expansion rate. We studied the effect of electron evaporation in this density range. Owing to the low density, the effects of three-body recombination were negligible. We modeled the expansion by taking into account the change in electron temperature owing to evaporation as well as adiabatic expansion and found good agreement with our data. We also developed a simple model for initial evaporation over a range of ultracold plasma densities, sizes, and electron temperatures to determine over what parameter range electron evaporation is expected to have a significant effect. We also report on a signal calibration technique, which relates the signal at our detector to the total number of ions and electrons in the ultracold plasma.
Hydrodynamics of stratified epithelium: steady state and linearized dynamics
Wei-Ting Yeh,Hsuan-Yi Chen
Quantitative Biology , 2015,
Abstract: A theoretical model for stratified epithelium is presented. The viscoelastic properties of the tissue is assumed to be dependent on the spatial distribution of proliferative and differentiated cells. Based on this assumption, a hydrodynamic description for tissue dynamics at long-wavelength, long-time limit is developed, and the analysis reveals important insight for the dynamics of an epithelium close to its steady state. When the proliferative cells occupy a thin region close to the basal membrane, the relaxation rate towards the steady state is enhanced by cell division and cell apoptosis. On the other hand, when the region where proliferative cells reside becomes sufficiently thick, a flow induced by cell apoptosis close to the apical surface could enhance small perturbations. This destabilizing mechanism is general for continuous self-renewal multi-layered tissues, it could be related to the origin of certain tissue morphology and developing pattern.
α-Galactosyl Phytosphingosine 2,6’-Diamide as an Inducer of Invariant Natural Killer T Cell  [PDF]
Ying-Cheng Huang, Wei-Ting Chen, Shu-Fan Tien, Ho-Lien Huang, Chun-Nan Yeh, Kun-I Lin, Chung-Shan Yu
Open Journal of Medicinal Chemistry (OJMC) , 2013, DOI: 10.4236/ojmc.2013.33008

Four a-galactosyl phytosphingosine 2,6’-diamide analogs were prepared from 2,6’-diamino a-galactosylphytosphingosine and the aromatic-bearing carboxylic acids. After purification with High Performance Liquid Chromatography, a flowcytometry for the four compounds for stimulation of human Va24+/Vb11+ NKT cell populations was carried out. Additional keto groups on the acyl chains of the 2,6’-diamide compound was associated with the enhanced stimulating effect.

MNSs Blood Group Glycophorin Variants in Taiwan: A Genotype-Serotype Correlation Study of ‘Mia’ and Sta with Report of Two New Alleles for Sta
Tai-Di Chen, Ding-Ping Chen, Wei-Ting Wang, Chien-Feng Sun
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0098166
Abstract: Background Glycophorin variants of the MNSs blood group are important in Taiwan. For more than 20 years, screening for the most frequent irregular antibody, anti-‘Mia’, has been conducted by using ‘Mia’(+) RBCs, with a significant success. However, the sensitivity and the specificity of this screening strategy have never been validated, and the true incidences of different glycophorin variants in Taiwan have been in controversy. Also, the significance of another less frequent and usually separately reported variant, Sta, has never been evaluated. Methodology/Principal Findings We ran a population-based screening (from unselected patients in our hospital) for MNSs blood group glycophorin variants by PCR-sequencing method. GP.Mur (Mil.III) was confirmed by sequence from 57 out of 1027 samples (5.6%), and there was no other Miltenberger subtype glycophorin variant found. Glycophorin variant Sta was found from 35 out of 1027 samples (3.4%). In contrast to anti-‘Mia’, which is the most frequently identified irregular antibody in Taiwan, the prevalence of anti-Sta was only 0.13% as determined by serologic method. In addition, two new alleles for Sta were found and reported. Conclusion/Significance We confirm the long-standing assumption that GP.Mur is the only prevalent Miltenberger subtype in Taiwan. The current anti-‘Mia’ screening method used in Taiwan, although neither sensitive nor specific, is still a suitable practice. Although Sta antigen has a high prevalence in Taiwan, routine screening for anti-Sta is not warranted based on current evidence.
Genetic and Mechanistic Evaluation for the Mixed-Field Agglutination in B3 Blood Type with IVS3+5G>A ABO Gene Mutation
Ding-Ping Chen, Ching-Ping Tseng, Wei-Ting Wang, Chien-Feng Sun
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037272
Abstract: Background The ABO blood type B3 is the most common B subtype in the Chinese population with a frequency of 1/900. Although IVS3+5G>A (rs55852701) mutation of B gene has been shown to associate with the development of B3 blood type, genetic and mechanistic evaluation for the unique mixed-field agglutination phenotype has not yet been completely addressed. Methodology/Principal Findings In this study, we analyzed 16 cases of confirmed B3 individuals and found that IVS3+5G>A attributes to all cases of B3. RT-PCR analyses revealed the presence of at least 7 types of aberrant B3 splicing transcripts with most of the transcripts causing early termination and producing non-functional protein during translation. The splicing transcript without exon 3 that was predicted to generate functional B3 glycosyltransferase lacking 19 amino acids at the N-terminal segment constituted only 0.9% of the splicing transcripts. Expression of the B3 cDNA with exon 3 deletion in the K562 erythroleukemia cells revealed that the B3 glycosyltransferase had only 40% of B1 activity in converting H antigen to B antigen. Notably, the typical mixed-field agglutination of B3-RBCs can be mimicked by adding anti-B antibody to the K562-B3 cells. Conclusions/Significance This study thereby demonstrates that both aberrant splicing of B transcripts and the reduced B3 glycosyltransferase activity contribute to weak B expression and the mixed-field agglutination of B3, adding to the complexity for the regulatory mechanisms of ABO gene expression.
Structure Determination of β-Glucans from Ganoderma lucidum with Matrix-assisted Laser Desorption/ionization (MALDI) Mass Spectrometry
Wei-Ting Hung,Shwu-Huey Wang,Chung-Hsuan Chen,Wen-Bin Yang
Molecules , 2008, DOI: 10.3390/molecules13081538
Abstract: A novel method that uses matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to analyze molecular weight and sequencing of glucan in Ganoderma lucidum is presented. Thus, β-glucan, which was isolated from fruiting bodies of G. lucidum, was measured in a direct and fast way using MALDI mass spectrometry. In addition, tandem mass spectrometry of permethylated glucans of G. lucidum, dextran, curdlan and maltohexaose were also pursued and different fragment patterns were obtained. The G. lucidum glucan structure was determined and this method for linkage analysis of permethylated glucan has been proven feasible.
Variational Study on a Dissipative Two-Level System

ZHU Wei-Ting,REN Qing-Bao,CHEN Qing-Hu,

中国物理快报 , 2008,
Effects of 17β-estradiol on Vitellogenin Inducement and Gonad Development in Male Tanichthys albonubes

WEN Ru-shu,FANG Zhan-qiang,CHEN Wei-ting,

动物学研究 , 2008,
Abstract: 以17β-雌二醇(E2)诱导雄性唐鱼产生卵黄蛋白原(Vtg),采用SephacrylS-300凝胶过滤层析柱提纯了雄鱼整体匀桨液的Vtg。结果显示,已确定被纯化的唐鱼Vtg在4%—7.5%Native—PAGE电泳中分子量为440kD左右,能同时被考马斯亮蓝、糖蛋白、磷蛋白、脂蛋白染色方法同时染色,是一种富含糖、磷、脂的蛋白。与对照组作比较,17β-雌二醇暴露组其体重明显下降(P<0.01),精巢发育滞后。结果表明,17β-雌二醇能够诱导雄性唐鱼产生大量的Vtg,并影响到其生长及精巢发育。雄性唐鱼Vtg可作为环境雌激素监测的有效生物学标记物。
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