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Search Results: 1 - 10 of 94255 matches for " Szu-Han Chen "
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Experiments on the morphology of icicles
Antony Szu-Han Chen,Stephen W. Morris
Physics , 2010,
Abstract: Icicles form when cool water drips from an overhanging support under ambient conditions which are below freezing. Ice growth is controlled by the removal of latent heat, which is transferred into the surrounding air via a thin film of water flowing over the ice surface. We describe laboratory experiments in which icicles were grown under controlled conditions. We used image analysis to probe the evolution of the icicle shape under various conditions. A recent asymptotic theory suggests that, overall, icicles converge to self-similar shapes which are predicted to be attractors. On the other hand, stability theory predicts that the ice-water interface can become unstable to form ripple patterns on the icicle surface. Our experimental results show that the predicted self-similar profile is only found in certain cases, and that icicles can also exhibit unpredicted non-uniformities such as branching near the tip. We find that pure water icicles are more likely to be self-similar than those grown from tap water. Ripples, which are also deviations from the self-similar profile, were observed to climb upward during icicle growth.
On the origin and evolution of icicle ripples
Antony Szu-Han Chen,Stephen W. Morris
Physics , 2013, DOI: 10.1088/1367-2630/15/10/103012
Abstract: Natural icicles often exhibit ripples about their circumference which are due to a morphological instability. We present an experimental study that explores the origin of the instability, using laboratory-grown icicles. Contrary to theoretical expectations, icicles grown from pure water do not exhibit growing ripples. The addition of a non-ionic surfactant, which reduces the surface tension, does not produce ripples. Instead, ripples emerge on icicles grown from water with dissolved ionic impurities. We find that even very small levels of impurity are sufficient to trigger ripples, and that the growth speed of the ripples increases very weakly with ionic concentration.
Small-Molecule Synthetic Compound Norcantharidin Reverses Multi-Drug Resistance by Regulating Sonic Hedgehog Signaling in Human Breast Cancer Cells
Yu-Jen Chen, Cheng-Deng Kuo, Szu-Han Chen, Wei-Jen Chen, Wen-Chien Huang, K. S. Clifford Chao, Hui-Fen Liao
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0037006
Abstract: Multi-drug resistance (MDR), an unfavorable factor compromising treatment efficacy of anticancer drugs, involves upregulated ATP binding cassette (ABC) transporters and activated Sonic hedgehog (Shh) signaling. By preparing human breast cancer MCF-7 cells resistant to doxorubicin (DOX), we examined the effect and mechanism of norcantharidin (NCTD), a small-molecule synthetic compound, on reversing multidrug resistance. The DOX-prepared MCF-7R cells also possessed resistance to vinorelbine, characteristic of MDR. At suboptimal concentration, NCTD significantly inhibited the viability of DOX-sensitive (MCF-7S) and DOX-resistant (MCF-7R) cells and reversed the resistance to DOX and vinorelbine. NCTD increased the intracellular accumulation of DOX in MCF-7R cells and suppressed the upregulated the mdr-1 mRNA, P-gp and BCRP protein expression, but not the MRP-1. The role of P-gp was strengthened by partial reversal of the DOX and vinorelbine resistance by cyclosporine A. NCTD treatment suppressed the upregulation of Shh expression and nuclear translocation of Gli-1, a hallmark of Shh signaling activation in the resistant clone. Furthermore, the Shh ligand upregulated the expression of P-gp and attenuated the growth inhibitory effect of NCTD. The knockdown of mdr-1 mRNA had not altered the expression of Shh and Smoothened in both MCF-7S and MCF-7R cells. This indicates that the role of Shh signaling in MDR might be upstream to mdr-1/P-gp, and similar effect was shown in breast cancer MDA-MB-231 and BT-474 cells. This study demonstrated that NCTD may overcome multidrug resistance through inhibiting Shh signaling and expression of its downstream mdr-1/P-gp expression in human breast cancer cells.
Predisposing Risk Factors for Delirium in Living Donor Liver Transplantation Patients in Intensive Care Units
Szu-Han Wang, Jiun-Yi Wang, Ping-Yi Lin, Kuo-Hua Lin, Chih-Jan Ko, Chia-En Hsieh, Hui-Chuan Lin, Yao-Li Chen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096676
Abstract: Background Delirium is one of the main causes of increased length of intensive care unit (ICU) stay among patients who have undergone living donor liver transplantation (LDLT). We aimed to evaluate risk factors for delirium after LDLT as well as to investigate whether delirium impacts the length of ICU and hospital stay. Methods Seventy-eight patients who underwent LDLT during the period January 2010 to December 2012 at a single medical center were enrolled. The Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) scale was used to diagnose delirium. Preoperative, postoperative, and hematologic factors were included as potential risk factors for developing delirium. Results During the study period, delirium was diagnosed in 37 (47.4%) patients after LDLT. The mean onset of symptoms occurred 7.0±5.5 days after surgery and the mean duration of symptoms was 5.0±2.6 days. The length of stay in the ICU for patients with delirium (39.8±28.1 days) was significantly longer than that for patients without delirium (29.3±19.0 days) (p<0.05). Risk factors associated with delirium included history of alcohol abuse [odds ratio (OR) = 6.40, 95% confidence interval (CI): 1.85–22.06], preoperative hepatic encephalopathy (OR = 4.45, 95% CI: 1.36–14.51), APACHE II score ≥16 (OR = 1.73, 95% CI: 1.71–2.56), and duration of endotracheal intubation ≥5 days (OR = 1.81, 95% CI: 1.52–2.23). Conclusions History of alcohol abuse, preoperative hepatic encephalopathy, APACHE II scores ≥16 and endotracheal intubation ≥5 days were predictive of developing delirium in the ICU following liver transplantation surgery and were associated with increased length of ICU and hospital stay.
Effect of Growth Hormone on Dawn Phenomenon in Healthy Adults  [PDF]
Kuang-Chung Shih, Sheng-Hwu Hsieh, Chii-Min Hwu, Ching-Fai Kwok, Szu-Han Chiu, Yu-Ching Chou, Low-Tone Ho
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2015, DOI: 10.4236/ojemd.2015.56008
Abstract: The purpose of this study was to investigate the involvement of growth hormone in the diurnal variation of insulin sensitivity in healthy adults. Afternoon (16:00 hr) or night (23:00 hr) pretreatment with a subcutaneous injection of normal saline, human growth hormone to mimic the normal nocturnal rise in growth hormone, or octreotide to inhibit endogenous growth hormone secretion to create a state of relative nocturnal growth hormone deficiency, was given 16 hours before undergoing the modified insulin suppression test in healthy subjects. The morning and evening experiments were separated by an interval of at least 3 days. Thus, each subject was tested on six separate occasions arranged in a random order. A higher value of the steady-state plasma glucose (SSPG) is indicative of lower insulin sensitivity. Plasma glucose, serum insulin, insulin-like growth factor-1, nonesterified fatty acids (NEFA), and metabolic clearance rate of insulin (MCRI) were measured. In the normal saline and human growth hormone groups, SSPG levels were lower in the morning than in the evening. Evening SSPG levels, MCRI, and NEFA concentrations were higher in the participants treated with normal saline and growth hormone than in the octreotide group. Differences in SSPG levels between the morning and evening values were higher in the participants pretreated with normal saline and growth hormone than in those treated with octreotide. A diurnal variation in insulin sensitivity existed in healthy subjects. These results provided direct evidence that the role of growth hormone in regulating insulin sensitivity might be related to changes in the MCRI and the metabolism of NEFA in healthy subjects.
Boundary value problems for some fully nonlinear elliptic equations
Szu-yu Sophie Chen
Mathematics , 2006,
Abstract: We consider a nonlinear version of the Yamabe problem on locally conformally flat compact manifolds with boundary. The main technique we used is to derive boundary $C^2$ estimates directly from boundary $C^0$ estimates. In particular, the result is a generalization of the work by Escobar.
Conformal Deformation to Scalar Flat Metrics with Constant Mean Curvature on the Boundary in Higher Dimensions
Szu-yu Sophie Chen
Mathematics , 2009,
Abstract: In 1992, motivated by Riemann mapping theorem, Escobar considered a version of Yamabe problem on manifolds of dimension n greater than 2 with boundary. The problem consists in finding a conformal metric such that the scalar curvature is zero and the mean curvature is constant on the boundary. By using a local test function construction, we are able to seattle the most cases left by Escobar's and Marques's works. Moreover, we reduce the remaining case to the positive mass theorem. In this proof, we use the method developed in previous works by Brendle and by Brendle and the author.
Conformal Deformation on Manifolds with Boundary
Szu-yu Sophie Chen
Mathematics , 2008,
Abstract: We consider natural conformal invariants arising from the Gauss-Bonnet formulas on manifolds with boundary, and study conformal deformation problems associated to them. The key technique we used is to derive boundary C^2 estimates directly from C^0 estimates for fully nonlinear equations. The main result has appeared in the author's thesis.
Optimal Curvature Decays on Asymptotically Locally Euclidean Manifolds
Szu-yu Sophie Chen
Mathematics , 2009,
Abstract: We present a method in nonlinear elliptic systems to study curvature decays on asymptotically locally Euclidean (ALE) manifolds. In particular, we show that scalar flat Kahler and harmonic ALE metrics of real dimension n are of order n-2.
Asymptotic Behaviors of Non-variational Elliptic Systems
Szu-yu Sophie Chen
Mathematics , 2009,
Abstract: We use a method, inspired by Pohozeav's work, to study asymptotic behaviors of non-variational elliptic systems in dimension n greater than two. The results apply to changing sign solutions.
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