Dynamics of Idiosyncratic Volatility and Market Volatility: An Emerging Market Perspective

Pei Pei Tan,Don U.A. Galagedera 연세대학교 동서문제연구원 2015 Global economic review Vol.44 No.1

Estimating idiosyncratic volatility (IVOL) using various model-dependent and model-independent measures, we investigate the characteristics of aggregate IVOL in Malaysia over the period 1990–2008. The IVOL estimated in all models have similar patterns and has no trend over the sample period. There is evidence of episodic phenomenon. During financial crisis periods, market volatility is relatively higher than IVOL – a plausible reason is high correlation between firms’ returns. Small firms and low-priced stocks appear to influence IVOL more than large firms and high-priced stocks. In Malaysia, market volatility and IVOL may predict GDP growth.

CYP1A1 MspI Polymorphism and Cervical Carcinoma Risk in the Multi-Ethnic Population of Malaysia: a Case-Control Study

Tan, Yee Hock,Sidik, Shiran Mohd,Husain, Sharifah Noor Akmal Syed,Lye, Munn Sann,Chong, Pei Pei Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.1

Background: Tobacco smoking is considered a risk factor for cervical cancer development due to the presence of tobacco based carcinogenic metabolites in cervical cells of female smokers. In this study, we investigated the role of the T3801C (MspI) polymorphism of CYP1A1, a gene encoding an enzyme necessary for the initiation of tobacco based carcinogen metabolism, on cervical cancer risk. The T to C substitution may alter CYP1A1 activities, potentially elevating cervical cancer risk. Since results of gene-disease association studies vary according to the study population, the multi-ethnic population of Malaysia provides an excellent representative cohort for identifying and comparing the cervical cancer risk among the 3 major ethnics in Southeast Asia in relation to CYP1A1 MspI polymorphism. Materials and Methods: A total of 195 Thin Prep Pap smear samples from HPV negative and cancer free females were randomly selected as controls while 106 formalin fixed paraffin embedded samples from females with invasive cervical cancer were randomly selected for the cases group. The polymorphisms were identified using restriction fragment length polymorphism (RFLP) PCR. Results: We found no significant associations between CYP1A1 MspI polymorphism and cervical cancer in the general Malaysian female population. However, upon ethnic stratification, the variant C/C genotype was significantly associated with a 4.66-fold increase in cervical cancer risk in Malay females (95% CI= 1.21-17.9; p=0.03). No significant association was observed in the Chinese and Indian females. Additionally, there were no significant associations in the dominant model and allele frequency model analysis in both the general and ethnically stratified female population of Malaysia. Conclusions: Our findings suggest that the C/C genotype of CYP1A1 MspI polymorphism is associated with the development of cervical carcinoma in the Malay females of Malaysia.

Radiation-induced Cochlea Hair Cell Death: Mechanisms and Protection

Tan, Pei-Xin,Du, Sha-Sha,Ren, Chen,Yao, Qi-Wei,Yuan, Ya-Wei Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.10

Cochlea hair cell death is regarded to be responsible for the radiation-induced sensorineural hearing loss (SNHL), which is one of the principal complications of radiotherapy (RT) for head and neck cancers. In this mini-review, we focus on the current progresses trying to unravel mechanisms of radiation-induced hair cell death and find out possible protection. P53, reactive oxygen species (ROS) and c-Jun N-terminal kinase (JNK) pathways have been proposed as pivotal in the processes leading to radiation hair cell death. Potential protectants, such as amifostine, N-acetylcysteine (NAC) and epicatechin (EC), are claimed to be effective at reducing radiation-inducedhair cell death. The RT dosage, selection and application of concurrent chemotherapy should be pre-examined in order to minimize the damage to cochlea hair cells.

Testing the effects of natural products on hair growth in stumptailed macauqe

( De-pei Tan ),( Quing-wei Wang ),( Seong-joon Moon ),( Young-guk Cho ),( Eui-dong Son ),( Woo-young Lee ) 대한화장품학회 1995 대한화장품학회지 Vol.21 No.2

The effect of natural products(drug 1,drug 2) on hair growth of frontal scalp of ten stumptailed macaques was investigated in period of 12 months. Drug 1 conteins extracts of Angelica gigantis Radix etc. and drug 2 conteins extracts of Corni Fructus, etc. Photographs of close view of the frontal scalp were taken once every month and folliclogram analysis has been done at pretretment and on 5th, 10th and 12th month after treatment. Drug 1 showed only slight effect or no effect on hair growth and drug 2 exhibited a significant degree of hair regrowth, but the control group exhibited a definite degree of regrowth and increasing density of vellus hair. Also, the physiological parameters, such as body weight, blood pressure, heart rate, serum levels of androgens, hematological measures during the treatment of drug 1,drug 2,and vehicle, were within normal limits. It indicates the drug 2 is the possible appearence of new summit of hair growth.

Applying the OMOP Common Data Model to Facilitate Benefit-Risk Assessments of Medicinal Products Using Real-World Data from Singapore and South Korea

Hui Xing Tan,Desmond Chun Hwee Teo,이동윤,김청수,Jing Wei Neo,Cynthia Sung,Haroun Chahed,Pei San Ang,Doreen Su Yin Tan,박래웅,Sreemanee Raaj Dorajoo 대한의료정보학회 2022 Healthcare Informatics Research Vol.28 No.2

Objectives: The aim of this study was to characterize the benefits of converting Electronic Medical Records (EMRs) to acommon data model (CDM) and to assess the potential of CDM-converted data to rapidly generate insights for benefitriskassessments in post-market regulatory evaluation and decisions. Methods: EMRs from January 2013 to December 2016were mapped onto the Observational Medical Outcomes Partnership-CDM (OMOP-CDM) schema. Vocabulary mappingswere applied to convert source data values into OMOP-CDM-endorsed terminologies. Existing analytic codes used in a priorOMOP-CDM drug utilization study were modified to conduct an illustrative analysis of oral anticoagulants used for atrialfibrillation in Singapore and South Korea, resembling a typical benefit-risk assessment. A novel visualization is proposed torepresent the comparative effectiveness, safety and utilization of the drugs. Results: Over 90% of records were mapped ontothe OMOP-CDM. The CDM data structures and analytic code templates simplified the querying of data for the analysis. Intotal, 2,419 patients from Singapore and South Korea fulfilled the study criteria, the majority of whom were warfarin users. After 3 months of follow-up, differences in cumulative incidence of bleeding and thromboembolic events were observable viathe proposed visualization, surfacing insights as to the agent of preference in a given clinical setting, which may meaningfullyinform regulatory decision-making. Conclusions: While the structure of the OMOP-CDM and its accessory tools facilitatereal-world data analysis, extending them to fulfil regulatory analytic purposes in the post-market setting, such as benefit-riskassessments, may require layering on additional analytic tools and visualization techniques.

Development of Integrated Electro-Hydraulic Braking System and Its ABS Application

Zhi-Hui Tan,Zhen-Fu Chen,Xiao-Fei Pei,Xue-Xun Guo,Shuang-Hong Pei 한국정밀공학회 2016 International Journal of Precision Engineering and Vol.17 No.3

This paper presented a new type of integrated EHB system. The EHB consisted of a compact three-chamber structure of master cylinder and mode switching valves. This allowed for the easy implementation of three different modes: normal mode, failsafe mode and ABS mode. In normal mode, a PWM control method was proposed for pressure regulation that took into account overshoot and hysteresis. To provide a favorable pedal feeling, a pedal stroke simulator was designed and integrated with the master cylinder. The failsafe and ABS modes were verified and the performance of the EHB in the three modes was evaluated using co-simulation and a bench test.

Enhanced Morris for the extraction of significant parameters in high-dimensional design optimization

Pei Yuan,Jin Cheng,Zhenyu Liu,Daxin Liu,Jianrong Tan 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.11

The traditional Morris method cannot ensure the consistent extraction of significant parameters because its random sampling strategy often leads to an improper coverage of the input space, especially when the number of sample points is small. To overcome the drawbacks, we developed an improved sampling strategy to enhance the performance of Morris method based on Latin hypercube sampling (LHS) with the idea of Central composite design (CCD) and a fluctuant step to generate a more uniform points set. A comparison on the results of a numerical example obtained by the enhanced Morris, the traditional methods and CCS-Morris demonstrated that the former had a much better performance. The application of the enhanced Morris method in the high-dimensional optimization of a compressor shell with 15 design parameters aimed at increasing its natural frequencies and keeping its mass relatively light demonstrates that the method is effective and applicable in engineering design.

Renin dependent hypertension caused by accessory renal arteries

Pei Lin Chan,Florence Hui Sieng Tan 대한고혈압학회 2019 Clinical Hypertension Vol.25 No.1

Background: Hypokalemia in the presence of hypertension is often attributed to primary hyperaldosteronism as a cause of secondary hypertension, however secondary hyperaldosteronism may present similarly. Accessory renal arteries are variants in the vascular anatomy which are often thought to be innocuous but in some circumstances can cause renovascular hypertension leading to secondary hyperaldosteronism. Case presentation: We report 2 cases of hypertension with secondary hyperaldosteronism associated with accessory renal arteries. Both patients presented with hypokalemia and further investigations revealed hyperaldosteronism with unsuppressed renin levels. Imaging studies showed the presence of accessory renal artery. Conclusion: Accessory renal arteries are a potential cause renovascular hypertension which can be detected via CT angiography or magnetic resonance angiography. Hormonal evaluation should be undertaken to determine whether its presence contributes to hypertension in the patient as targeted treatment such as aldosterone antagonist can be initiated. Surgical intervention or renal denervation may be considered in resistant cases.

A predicting model for thermal conductivity of high permeability-high strength concrete materials

Tan, Yi-Zhong,Liu, Yuan-Xue,Wang, Pei-Yong,Zhang, Yu Techno-Press 2016 Geomechanics & engineering Vol.10 No.1

The high permeability-high strength concrete belongs to the typical of porous materials. It is mainly used in underground engineering for cold area, it can act the role of heat preservation, also to be the bailing and buffer layer. In order to establish a suitable model to predict the thermal conductivity and directly applied for engineering, according to the structure characteristics, the thermal conductivity predicting model was built by resistance network model of parallel three-phase medium. For the selected geometric and physical cell model, the thermal conductivity forecast model can be set up with aggregate particle size and mixture ratio directly. Comparing with the experimental data and classic model, the prediction model could reflect the mixture ratio intuitively. When the experimental and calculating data are contrasted, the value of experiment is slightly higher than predicting, and the average relative error is about 6.6%. If the material can be used in underground engineering instead by the commonly insulation material, it can achieve the basic requirements to be the heat insulation material as well.

PREPARATION OF NANO-TATB BY SEMIBATCH REACTION CRYSTALLIZATION

XUE-RONG TAN,XIAO-HUI DUAN,CHONG-HUA PEI,HONG-LIN XU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.5

The 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) nanoparticles were prepared by using semibatch reaction crystallization method, and the influencing factors in close relationship with the grain size and crystal morphology control, such as the concentration of reaction system and categories of surfactants, were studied in this paper. The synthesized nano-TATB particles had been characterized by SEM, XRD, thermo gravimetric/differential scanning calorimetric (TG/DSC) and N2 physisorption. The grain size of TATB particles using nonionic surfactant as the additive ranged from 30 nm to 65 nm with a shape of spheres or ellipsoids. The broadening of the peaks and the weakening of the strength for nano-TATB were observed by XRD analysis. The corrected average particle size of nano-TATB was calculated using the Debye–Scherrer equation and the range was from 18 nm to 50 nm. TG and DSC curves revealed that thermal decomposition of nano-TATB occurred in the range of 361.5°C–385.0°C and its peak temperature was 373.7°C with a decrease of approximately 7°C compared with original TATB. Furthermore, the specific surface area (21.54 m2/g) of nano-TATB was calculated by BET method using N2 physisorption (at 77°C).