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Search Results: 1 - 10 of 178109 matches for " K. Y. Chew "
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Physical activity engagement after breast cancer: Advancing the health of survivors  [PDF]
S. Y. Loh, S. L. Chew, K. F. Quek
Health (Health) , 2013, DOI: 10.4236/health.2013.55111

Background: Physical inactivity is identified as the fourth leading risk factor for global mortality and associated with increased breast cancer diagnosis and risks of recurrence. Objectives: To investigate the level of physical activity engagement after breast cancer in survivors and healthy controls. Design: A descriptive casecontrol study on survivors and matched (ethnic, gender, age) healthy controls was surveyed using a pre-post questionnaire and a 1-minute cancer control media. The socio- and medical demographic data, physical activity status information were obtained from self report questionnaires. Results: Breast cancer survivors (n = 51) were found to participate in low-moderate level of physical activity while healthy controls (n = 45) participated in moderate-vigorous level of physical activity. Healthy adults reported more barriers and excuses but all participants (90% survivors and control) were unaware of the strong inverse relationship between level of physical activity and risks of cancer recurrence. The post test on video showed an increased awareness and intention to re-engagement in physical activity for cancer control (M = 7.1 ± 1.53, p < 0.01). Conclusion: The finding suggests that simple public health message within the Model of cancer survivorship care must be disseminated. The “teachable moments” after a cancer diagnosis should be optimised to promote rehabilitation for physically active lifestyle.

Synthesis of Barium Nickel Titanium Oxide Stabilized by Citric Acid  [PDF]
K. Y. Chew, M. Abu Bakar, N.H.H. Abu Bakar
Modeling and Numerical Simulation of Material Science (MNSMS) , 2013, DOI: 10.4236/mnsms.2013.31B007
Abstract: Barium nickel titanium oxide particles (Ba2NiTi5O13) were synthesized in the presence of citric acid by using a two step sol-gel method followed by calcination. The addition of citric acid as a stabilizer (mole ratio of 0.5, 1.0, 2.0, 4.0) resulted in the formation of Ba2NiTi5O13 particles with various morphology (i.e. sphere, cube, rod). These various morphology changes were deduced to be caused by citric acid that tends to absorbed on certain dimension of the Ba2NiTi5O13 particles when different concentration of citric acid was added. Besides that, the growth of Ba2NiTi5O13 particles from incorporation of bulky micelles which act as a protective 'shell' that control particle sizes by attaching on the surfaces of particles.
Near-Infrared Light Curves of the Brown Dwarf Eclipsing Binary 2MASS J05352184-0546085: Can Spots Explain the Temperature Reversal?
Y. Gómez Maqueo Chew,K. G. Stassun,A. Prsa,R. D. Mathieu
Physics , 2009, DOI: 10.1088/0004-637X/699/2/1196
Abstract: We present the JHKs light curves for the double-lined eclipsing binary 2MASS J05352184-0546085, in which both components are brown dwarfs. We analyze these light curves with the published Ic-band light curve and radial velocities to provide refined measurements of the system's physical parameters. The component masses and radii are here determined with an accuracy of ~6.5% and ~1.5%, respectively. We confirm the previous surprising finding that the primary brown dwarf has a cooler effective temperature than its companion. Next, we perform a detailed study of the variations in the out-of-eclipse phases of the light curves to ascertain the properties of any inhomogeneities on the surfaces of the brown dwarfs. Our analysis reveals two low-amplitude periodic signals, one attributable to the rotation of the primary (with a period of 3.293+/-0.001 d) and the other to that of the secondary (14.05+/-0.05 d). Finally, we explore the effects on the derived physical parameters of the system when spots are included in the modeling. The observed low-amplitude rotational modulations are well fit by cool spots covering a small fraction of their surfaces. To mimic the observed ~200 K suppression of the primary's temperature, our model requires that the primary possess a very large spot coverage fraction of ~65%. Altogether, a spot configuration in which the primary is heavily spotted while the secondary is lightly spotted can explain the apparent temperature reversal and can bring the temperatures of the brown dwarfs into agreement with the predictions of theoretical models.
A Strict Test of Stellar Evolution Models: The Absolute Dimensions of Massive Benchmark Eclipsing Binary V578 Mon
E. V. Garcia,Keivan G. Stassun,K. Pavlovski,H. Hensberge,Y. Gómez Maqueo Chew,A. Claret
Physics , 2014, DOI: 10.1088/0004-6256/148/3/39
Abstract: We determine the absolute dimensions of the eclipsing binary V578 Mon, a detached system of two early B-type stars (B0V + B1V, P$=$2.40848 d) in the star-forming region NGC 2244 of the Rosette Nebula. From the light curve analysis of 40 yr of photometry and the analysis of HERMES spectra, we find radii of $5.41\pm0.04$ Rsun and $4.29\pm 0.05$ Rsun, and temperatures of $ 30000\pm 500$~K and $ 25750\pm 435$ K respectively. We find that our disentangled component spectra for V578 Mon agree well previous spectral disentangling from the literature. We also reconfirm the previous spectroscopic orbit of V578 Mon finding that masses of $ 14.54\pm 0.08$ Msun and $ 10.29\pm 0.06$ Msun are fully compatible with the new analysis. We compare the absolute dimensions to the rotating models of the Geneva and Utrecht groups and the models of Granada group. We find all three sets of models marginally reproduce the absolute dimensions of both stars with a common age within uncertainty for gravity-effective temperature isochrones. However - there are some apparent age discrepancies for the corresponding mass-radius isochrones. Models with larger convective overshoot $>0.35$ worked best. Combined with our previously determined apsidal motion of $0.07089^{+0.00021}_{-0.00013}$ deg cycle$^{-1}$, we compute the internal structure constants (tidal Love number) for the newtonian and general relativistic contribution to the apsidal motion, $\log{k_2}=-1.975\pm0.017$ and $\log{k_2}=-3.412\pm0.018$ respectively. We find the relativistic contribution to the apsidal motion of be small $<4\%$. We find that the prediction of $\log{k_{\rm 2,theo}}=-2.005\pm0.025$ of the Granada models fully agrees with our observed $\log{k_2}$.
High Brain Ammonia Tolerance and Down-Regulation of Na+:K+:2Cl- Cotransporter 1b mRNA and Protein Expression in the Brain of the Swamp Eel, Monopterus albus, Exposed to Environmental Ammonia or Terrestrial Conditions
Yuen K. Ip, Zhisheng Hou, Xiu L. Chen, Jasmine L. Y. Ong, You R. Chng, Biyun Ching, Kum C. Hiong, Shit F. Chew
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069512
Abstract: Na+:K+:2Cl- cotransporter 1 (NKCC1) has been implicated in mediating ischemia-, trauma- or ammonia-induced astrocyte swelling/brain edema in mammals. This study aimed to determine the effects of ammonia or terrestrial exposure on ammonia concentrations in the plasma and brain, and the mRNA expression and protein abundance of nkcc/Nkcc in the brain, of the swamp eel Monopterus albus. Ammonia exposure led to a greater increase in the ammonia concentration in the brain of M. albus than terrestrial exposure. The brain ammonia concentration of M. albus reached 4.5 μmol g-1 and 2.7 μmol g-1 after 6 days of exposure to 50 mmol l-1 NH4Cl and terrestrial conditions, respectively. The full cDNA coding sequence of nkcc1b from M. albus brain comprised 3276 bp and coded for 1092 amino acids with an estimated molecular mass of 119.6 kDa. A molecular characterization indicated that it could be activated through phosphorylation and/or glycosylation by osmotic and/or oxidative stresses. Ammonia exposure for 1 day or 6 days led to significant decreases in the nkcc1b mRNA expression and Nkcc1b protein abundance in the brain of M. albus. In comparison, a significant decrease in nkcc1b mRNA expression was observed in the brain of M. albus only after 6 days of terrestrial exposure, but both 1 day and 6 days of terrestrial exposure resulted in significant decreases in the protein abundance of Nkcc1b. These results are novel because it has been established in mammals that ammonia up-regulates NKCC1 expression in astrocytes and NKCC1 plays an important role in ammonia-induced astrocyte swelling and brain edema. By contrast, our results indicate for the first time that M. albus is able to down-regulate the mRNA and protein expression of nkcc1b/Nkcc1b in the brain when confronted with ammonia toxicity, which could be one of the contributing factors to its extraordinarily high brain ammonia tolerance.
Molecular Characterization of Branchial aquaporin 1aa and Effects of Seawater Acclimation, Emersion or Ammonia Exposure on Its mRNA Expression in the Gills, Gut, Kidney and Skin of the Freshwater Climbing Perch, Anabas testudineus
Yuen K. Ip, Melody M. L. Soh, Xiu L. Chen, Jasmine L. Y. Ong, You R. Chng, Biyun Ching, Wai P. Wong, Siew H. Lam, Shit F. Chew
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061163
Abstract: We obtained a full cDNA coding sequence of aquaporin 1aa (aqp1aa) from the gills of the freshwater climbing perch, Anabas testudineus, which had the highest expression in the gills and skin, suggesting an important role of Aqp1aa in these organs. Since seawater acclimation had no significant effects on the branchial and intestinal aqp1aa mRNA expression, and since the mRNA expression of aqp1aa in the gut was extremely low, it can be deduced that Aqp1aa, despite being a water channel, did not play a significant osmoregulatory role in A. testudineus. However, terrestrial exposure led to significant increases in the mRNA expression of aqp1aa in the gills and skin of A. testudineus. Since terrestrial exposure would lead to evaporative water loss, these results further support the proposition that Aqp1aa did not function predominantly for the permeation of water through the gills and skin. Rather, increased aqp1aa mRNA expression might be necessary to facilitate increased ammonia excretion during emersion, because A. testudineus is known to utilize amino acids as energy sources for locomotor activity with increased ammonia production on land. Furthermore, ammonia exposure resulted in significant decreases in mRNA expression of aqp1aa in the gills and skin of A. testudineus, presumably to reduce ammonia influx during ammonia loading. This corroborates previous reports on AQP1 being able to facilitate ammonia permeation. However, a molecular characterization of Aqp1aa from A. testudineus revealed that its intrinsic aquapore might not facilitate NH3 transport. Hence, ammonia probably permeated the central fifth pore of the Aqp1aa tetramer as suggested previously. Taken together, our results indicate that Aqp1aa might have a greater physiological role in ammonia excretion than in osmoregulation in A. testudineus.
Luminosity Discrepancy in the Equal-Mass, Pre--Main Sequence Eclipsing Binary Par 1802: Non-Coevality or Tidal Heating?
Y. Gómez Maqueo Chew,K. G. Stassun,A. Pr?a,E. Stempels,L. Hebb,R. Barnes,R. Heller,R. D. Mathieu
Physics , 2011, DOI: 10.1088/0004-637X/745/1/58
Abstract: Parenago 1802, a member of the ~1 Myr Orion Nebula Cluster, is a double-lined, detached eclipsing binary in a 4.674 d orbit, with equal-mass components (M_2/M_1 = 0.985 \pm 0.029). Here we present extensive VIcJHKs light curves spanning ~15 yr, as well as a Keck/HIRES optical spectrum. The light curves evince a third light source that is variable with a period of 0.73 d, and is also manifested in the high-resolution spectrum, strongly indicating the presence of a third star in the system, probably a rapidly rotating classical T Tauri star. We incorporate this third light into our radial velocity and light curve modeling of the eclipsing pair, measuring accurate masses (M_1 = 0.391 \pm 0.032, M_2 = 0.385 \pm 0.032 M\odot), radii (R_1 = 1.73 \pm 0.02, R_2 = 1.62 \pm 0.02 R\odot), and temperature ratio (T_1/T_2 = 1.0924 \pm 0.0017). Thus the radii of the eclipsing stars differ by 6.9 \pm 0.8%, the temperatures differ by 9.2 \pm 0.2%, and consequently the luminosities differ by 62 \pm 3%, despite having masses equal to within 3%. This could be indicative of an age difference of ~3x10^5 yr between the two eclipsing stars, perhaps a vestige of the binary formation history. We find that the eclipsing pair is in an orbit that has not yet fully circularized, e = 0.0166 \pm 0.003. In addition, we measure the rotation rate of the eclipsing stars to be 4.629 \pm 0.006 d; they rotate slightly faster than their 4.674 d orbit. The non-zero eccentricity and super-synchronous rotation suggest that the eclipsing pair should be tidally interacting, so we calculate the tidal history of the system according to different tidal evolution theories. We find that tidal heating effects can explain the observed luminosity difference of the eclipsing pair, providing an alternative to the previously suggested age difference.
A Fast Multipole Method for Embedded Structure in a Stratified Medium
Y. C. Pan W. C. Chew
PIER , 2004, DOI: 10.2528/PIER03050602
Abstract: An efficient, static fast multipole method (FMM) based algorithm is presented in this paper for the evaluation of the parasitic capacitance of 3-D microstrip signal lines embedded in stratified dielectric media. The effect of dielectric interfaces on the capacitance matrix is included in the stage of FMM when outgoing multipole expansions are used to form local multipole expansions. The algorithm retains computational and memory complexity of the free-space FMM, where is the number of conductor patches.
Simple shear behaviour of palm biodiesel contaminated soil
Chew S. J.,C. Y. Lee
Journal of Engineering and Applied Sciences , 2010,
Abstract: Palm biodiesel contaminations may bring adverse effect on basic geotechnical properties of foundation soils. This paper presents the results of an experimental study on shear behaviour of palm biodiesel contaminated sandy soil. A comprehensive set of laboratory experiments have been undertaken in a direct simple shear device on samples of palm biodiesel contaminated sandy soil. In the experiments the soil samples were prepared by mixing the sandy soil with B20 palm biodiesel ranging from 0% to 20% by weight. Stress-strain and shear strength response for the samples were monitored continuously during the experiments. The effect of the palm biodiesel content, relative density and normal stress on the shear behaviour of the sandy soil is investigated and discussed.
High-Content, High-Throughput Analysis of Cell Cycle Perturbations Induced by the HSP90 Inhibitor XL888
Susan K. Lyman,Suzanne C. Crawley,Ruoyu Gong,Joanne I. Adamkewicz,Garth McGrath,Jason Y. Chew,Jennifer Choi,Charles R. Holst,Leanne H. Goon,Scott A. Detmer,Jana Vaclavikova,Mary E. Gerritsen,Robert A. Blake
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0017692
Abstract: Many proteins that are dysregulated or mutated in cancer cells rely on the molecular chaperone HSP90 for their proper folding and activity, which has led to considerable interest in HSP90 as a cancer drug target. The diverse array of HSP90 client proteins encompasses oncogenic drivers, cell cycle components, and a variety of regulatory factors, so inhibition of HSP90 perturbs multiple cellular processes, including mitogenic signaling and cell cycle control. Although many reports have investigated HSP90 inhibition in the context of the cell cycle, no large-scale studies have examined potential correlations between cell genotype and the cell cycle phenotypes of HSP90 inhibition.
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