Displaying publications 1 - 20 of 42 in total

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  1. Lim SC
    J Phys Condens Matter, 2006 May 3;18(17):4329-43.
    PMID: 21690785 DOI: 10.1088/0953-8984/18/17/019
    The second harmonic generation of antiferromagnetic and dielectric multilayers is analysed by using a conventional nonlinear optics approach and transfer matrix formalism. The theoretical modelling of the multilayers is configured in Voigt geometry in order to observe second harmonic transmission and reflection through the film system, with the assumption of weak nonlinearity and no depletion of incident waves. With these, some of the linear and second harmonic transmissions and reflections are calculated numerically and shown graphically.
  2. Lim SC, Muniandy SV
    Phys Rev E Stat Nonlin Soft Matter Phys, 2002 Aug;66(2 Pt 1):021114.
    PMID: 12241157
    We study some Gaussian models for anomalous diffusion, which include the time-rescaled Brownian motion, two types of fractional Brownian motion, and models associated with fractional Brownian motion based on the generalized Langevin equation. Gaussian processes associated with these models satisfy the anomalous diffusion relation which requires the mean-square displacement to vary with t(alpha), 0
  3. Muniandy SV, Lim SC
    Phys Rev E Stat Nonlin Soft Matter Phys, 2001 Apr;63(4 Pt 2):046104.
    PMID: 11308909
    Fractional Brownian motion (FBM) is widely used in the modeling of phenomena with power spectral density of power-law type. However, FBM has its limitation since it can only describe phenomena with monofractal structure or a uniform degree of irregularity characterized by the constant Holder exponent. For more realistic modeling, it is necessary to take into consideration the local variation of irregularity, with the Holder exponent allowed to vary with time (or space). One way to achieve such a generalization is to extend the standard FBM to multifractional Brownian motion (MBM) indexed by a Holder exponent that is a function of time. This paper proposes an alternative generalization to MBM based on the FBM defined by the Riemann-Liouville type of fractional integral. The local properties of the Riemann-Liouville MBM (RLMBM) are studied and they are found to be similar to that of the standard MBM. A numerical scheme to simulate the locally self-similar sample paths of the RLMBM for various types of time-varying Holder exponents is given. The local scaling exponents are estimated based on the local growth of the variance and the wavelet scalogram methods. Finally, an example of the possible applications of RLMBM in the modeling of multifractal time series is illustrated.
  4. Tang SP, Lim SC, Arkachaisri T
    J Clin Med, 2021 Feb 03;10(4).
    PMID: 33546120 DOI: 10.3390/jcm10040559
    Childhood onset systemic lupus erythematosus is a rare disease that is more common amongst Southeast Asian children compared to the West. It is typified by a peripubertal onset and a female preponderance, which increases with advancing age. Organs commonly involved at diagnosis include haematological, renal, and mucocutaneous. Fever, malar rash, and cutaneous vasculitis are common. Lupus nephritis is typically proliferative especially Class IV and contributes to both disease activity and damage. Antinuclear antibody and anti-dsDNA positivity are both prevalent in this region. Disease activity is higher than Western cohorts at onset but responds to therapy reducing to low disease activity by six months. However, organ damage occurs early and continues to accumulate over the time, a consequence of both active disease (neurological and renal systems) and steroid-related complications especially in the eye (cataract and glaucoma) and musculoskeletal systems (avascular necrosis). Infections remain the leading cause of death and mortality in this region is highly variable contributed by the heterogeneity in social economic status, healthcare access, and availability of paediatric rheumatology expertise in the region.
  5. Lim SC, Johari B, Tang SP
    Malays Fam Physician, 2021 Nov 30;16(3):115-118.
    PMID: 34938402 DOI: 10.51866/cr1176
    A seven-year-old girl presented with pain in multiple joints and constitutional symptoms over a period of four months. There were no significant clinical findings apart from joint tenderness. Blood test results did not indicate any specific pathology and initial radiology imaging was normal. Subsequent careful examination of her X-ray images led to an MRI of her left knee, which revealed acute osteonecrotic changes. A following whole-body MRI examination demonstrated multifocal bony lesions. Bone marrow examination conclusively diagnosed acute lymphoblastic leukaemia (ALL). Acute osteonecrosis has classically been described as a complication of treatment in children with ALL and has not been recognised as a presenting feature until recently.
  6. Nazri K, Lim SC, Gomes C
    F1000Res, 2021;10:921.
    PMID: 34909192 DOI: 10.12688/f1000research.73064.2
    Introduction: Malaysia is one of the countries with the highest lightning flash density globally. While sufficiency of lightning protection system is crucial to ensure human safety against lightning strikes, the public awareness towards lightning safety is also equally important in Malaysia. Hence, this study was conducted to understand the current lightning safety awareness level of the Malaysian population. Methods: An online questionnaire survey which consists of 22 scientific statements of lightning was first developed in Malay and English. The questionnaire allows the respondent to also check their own score upon completion of the questionnaire. It was then distributed to the public for data collection. The sample size comprised of both genders, all layers of society from various educational level and social background. Results: Overall, the awareness on lightning safety amongst Malaysian is at moderate level with an average score of slightly above 50%. Urbanites scored marginally better than their rural counterparts. One's education level does not dictate their awareness level of lightning safety. Discussion: In conclusion, the public in Malaysia needs to be better educated on lightning safety. Similar studies should be replicated in other countries experiencing similar levels of lightning activity to better understand the public's perception on lightning.
  7. Lim SC, Chan YM, Gan WY
    PMID: 36900997 DOI: 10.3390/ijerph20053977
    Quality of life (QOL) of older adults is a complex issue that requires an understanding of the intersection between socioeconomic and health factors. A poor quality of life (QOL) is frequently reported as sub-optimal among older adults whereby concerted and collective actions are required through an evidence-based approach. Hence, this cross-sectional study aims to determine the social and health predictors of the QOL of a community-dwelling older adult Malaysian population through a quantitative household survey using multi-stage sampling. A total of 698 respondents aged 60 years old and older were recruited and the majority of them had a good quality of life. Risk of depression, disability, living with stroke, low household income, and lack of social network were identified as the predictors of a poor QOL among the community-dwelling older Malaysians. The identified predictors for QOL provided a list of priorities for the development of policies, strategies, programmes, and interventions to enhance the QOL of the community-dwelling older Malaysians. Multisectoral approaches, especially collective efforts from both social and health sectors, are required to address the complexities of the ageing issues.
  8. Lim SC, Rahman A, Yaacob NM
    Malays J Med Sci, 2019 Jan;26(1):87-98.
    PMID: 30914896 MyJurnal DOI: 10.21315/mjms2019.26.1.8
    Background: Pre-hospital delay is currently a major factor limiting early reperfusion among ST-elevation myocardial infarction (STEMI) patients worldwide. This study aims to determine pre-hospital factors affecting symptom-to-door time among STEMI patients in Malaysia.

    Methods: This cross-sectional study included 222 STEMI patients admitted to two tertiary hospitals in Malaysia. By determining symptom-to-door time, the study population was categorised into two definitive treatment seeking groups: early (≤ 3 h) and delayed (> 3 h). Data was collected focusing on socio-demographical data, risk factors and comorbidities, clinical presentation, situational factors and action taken by patients.

    Results: The mean age of our patients was 58.0 (SD = 11.9) years old, and the population consisted of 186 (83.8%) males and 36 (16.2%) females. Our study found that the median symptom-to-door time was 130.5 (IQR 240) min, with 64% of subjects arriving early and 36% arriving late. Pre-hospital delays were found to be significant among females (adj OR = 2.42; 95% CI: 1.02, 5.76; P = 0.046), patients with recurrence of similar clinical presentations (adj OR = 2.74; 95% CI: 1.37, 5.46; P = 0.004), patients experiencing atypical symptoms (adj OR = 2.64; 95% CI: 1.11, 6.31; P = 0.029) and patients who chose to have their first medical contact (FMC) for their symptoms with a general practitioner (adj OR = 2.80; 95% CI: 1.20, 6.56; P = 0.018). However, patients with hyperlipidaemia (adj OR = 0.46; 95% CI: 0.23, 0.93; P = 0.030), self-perceived cardiac symptoms (adj OR = 0.36; 95% CI: 0.17, 0.73; P = 0.005) and symptoms that began in public places (adj OR = 0.21; 95% CI: 0.06, 0.69; P = 0.010) tended to seek treatment earlier.

    Conclusion: The symptom-to-door time among the Malaysian population is shorter in comparison to other developing countries. Nevertheless, identified, modifiable pre-hospital factors can be addressed to further shorten symptom-to-door time among STEMI patients.

  9. Thevarajah M, Chew YY, Lim SC, Sabir N, Sickan J
    Malays J Pathol, 2009 Jun;31(1):23-7.
    PMID: 19694310 MyJurnal
    To establish trimester specific reference intervals for thyroid hormones during pregnancy in Malaysian women.
  10. Amekyeh H, Billa N, Yuen KH, Lim SC
    AAPS PharmSciTech, 2015 Oct 28.
    PMID: 26511938
    Amphotericin B (AmB) is poorly absorbed from the gastrointestinal tract. Recent studies have suggested enhanced drug absorption from solid lipid nanoparticles (SLN). Little is known of the fate of AmB absorption within the gastrointestinal tract, and no gastrointestinal transit study has yet been performed on AmB-containing nano-formulations. We aimed to investigate the effect of food on the gastrointestinal transit properties of an AmB-containing SLN in rats. Three SLNs containing AmB, paracetamol, or sulfasalazine were formulated using cocoa butter and beeswax as lipid matrices and simultaneously administered orally to Sprague-Dawley rats. Paracetamol and sulfapyridine were used as marker drugs for estimating gastric emptying and cecal arrival, respectively. The pharmacokinetic data generated for paracetamol and sulfapyridine were used in estimating the absorption of the AmB SLNs in the small and large intestines, respectively. A delayed rate of AmB absorption was observed in the fed state; however, the extent of absorption was not affected by food. Specifically, the percentages of AmB absorption during the fasted state in the stomach, small intestine, and colon were not significantly different from absorption within the respective regions in the fed state. In both states, however, absorption was highest in the colon and appeared to be a combination of absorption from the small intestine plus absorption proper within the colon. The study suggests that AmB SLN, irrespective of food status, is slowly but predominantly taken up by the lymph, making the small intestine the most favorable site for the delivery of the AmB SLNs.
  11. Lim SC, Chan EWL, Tang SP
    Lupus, 2020 Aug;29(9):1106-1114.
    PMID: 32631203 DOI: 10.1177/0961203320939185
    BACKGROUND: Paediatric systemic lupus erythematosus is a rare autoimmune disease with a wide spectrum of clinical presentation in different populations. We present a cohort of paediatric systemic lupus erythematosus in Malaysia where the disease features and outcomes are still largely unknown.

    METHODS: A retrospective review of all paediatric systemic lupus erythematosus patients with at least 6 months follow-up at Selayang Hospital from 2004 to 2016. Epidemiological, clinical and outcome data were collected and analysed.

    RESULTS: A total of 141 paediatric systemic lupus erythematosus patients, 87.9% females, were followed up for a median 6.3 years (interquartile range 3.6-9.0). The median age at diagnosis was 10.8 years (interquartile range 9.0-12.0 years), positive family history of systemic lupus erythematosus was present in 12.1% and the majority (61.7%) were of Malay ethnicity. Common presentations included fever (87.2%), vasculitic rash (72.3%) and lethargy (69.5%). At diagnosis, leukopenia (51.1%), thrombocytopenia (41.8%) and cutaneous lupus (56%) predominate with significant renal involvement (39.7%). Renal (45.4%), liver (26%) and the central nervous system (17%) were important major organs involved during the course of the disease. At diagnosis, almost all (99.3%) patients had high disease activity (mean Systemic Lupus Erythematosus Disease Activity Index score 20.1 ± 9.6). The majority (62.4%) achieved remission or low disease activity after 6 months, maintained over the next 10 years. Damage occurred early (39.1% at 1 year) and increased with time. Ocular damage was the most common side effect (29%) and was predominantly corticosteroid related (93%). Growth retardation was significant (38.2%) with no gonadal failure or secondary malignancies. End-stage renal disease occurred in 3.1% patients whereas 53.1% had sustained renal remission. Overall mortality was 1.4%.

    CONCLUSION: Despite high disease activity at diagnosis, the majority had good sustained response to treatment with low overall mortality. However, there was progressive accrual of organ damage, highlighting the need for further research and refinements into therapies for paediatric systemic lupus erythematosus.

  12. Yusfiandika F, Lim SC, Gomes C, Chockalingam A, Cheng Pay L
    F1000Res, 2021 09 09;10:906.
    PMID: 34804502 DOI: 10.12688/f1000research.70650.2
    Background COVID-19 has drastically dampened human activities since early 2020. Studies have shown that this has resulted in changes in air temperature and humidity. Since lightning activities are dependent on air temperature and humidity, this study is conducted to evaluate the correlation between the intensity of lightning activities with the atmospheric changes, and investigates the changes, in lightning activities due to atmospheric changes during the COVID-19 pandemic. Methods The hypothesis was tested through a t-test and Pearson's correlation study. The variation trend of lightning strikes count (LSC) in Europe and Oceania during the five months COVID-19 lockdown period (March - July) compared to the same period in the previous five years from 2015 to 2019 is investigated. Results Statistical analysis shows the LSC in Europe and Oceania during the lockdown period dropped significantly by more than 50% and 44% respectively compared to the same period in previous five years. Furthermore, LSC was found to be positively correlated with air temperature and relative humidity in Europe. However, in Oceania, LSC seems to be only positively correlated with air temperature but negatively correlated with relative humidity. Conclusions This study seems to suggest that lightning activities have significantly changed during this pandemic due to reduction in human activities.
  13. Sabanayagam C, Shankar A, Lim SC, Tai ES, Wong TY
    Asia Pac J Public Health, 2011 Nov;23(6):936-45.
    PMID: 20460283 DOI: 10.1177/1010539510361637
    Studies conducted in Western populations demonstrate that blood pressure (BP) is a major risk factor for chronic kidney disease (CKD). The authors examined the cross-sectional association between BP and CKD in 3280 adults of Malay ethnicity aged 40 to 80 years living in Singapore. CKD was defined as (1) estimated glomerular filtration rate (eGFR) of < 60 mL/min/1.73 m(2) and (2) presence of microalbuminuria/macroalbuminuria. They observed a dose-dependent positive association between BP and CKD (P trend < .0001). In multivariable-adjusted analysis, compared with participants with normal BP, the odds ratio (OR; 95% confidence interval [CI]) of eGFR < 60 mL/min/1.73 m(2) was 1.85 (0.95-3.62), 2.95 (1.55-5.64), and 4.96 (2.63-9.37) for prehypertension, and stage 1 and stage 2 hypertension, respectively. Similar results were obtained for microalbuminuria/macroalbuminuria. Stage 2 hypertension had the greatest population-attributable risk of CKD (23%). The strong positive association of hypertension with CKD emphasizes the need to control BP in Asian populations to reduce the burden of kidney disease.
  14. Sabanayagam C, Lim SC, Wong TY, Lee J, Shankar A, Tai ES
    Nephrol Dial Transplant, 2010 Aug;25(8):2564-70.
    PMID: 20185856 DOI: 10.1093/ndt/gfq084
    There is substantial heterogeneity in literature regarding the epidemiology for chronic kidney disease (CKD) in different Asian populations. We aimed to assess the prevalence and risk factors of CKD in a multi-ethnic Asian population in Singapore.
  15. Chua KH, Lim SC, Ng CC, Lee PC, Lim YA, Lau TP, et al.
    Sci Rep, 2015;5:15671.
    PMID: 26507008 DOI: 10.1038/srep15671
    Molecular detection has overcome limitations of microscopic examination by providing greater sensitivity and specificity in Plasmodium species detection. The objective of the present study was to develop a quantitative real-time polymerase chain reaction coupled with high-resolution melting (qRT-PCR-HRM) assay for rapid, accurate and simultaneous detection of all five human Plasmodium spp. A pair of primers targeted the 18S SSU rRNA gene of the Plasmodium spp. was designed for qRT-PCR-HRM assay development. Analytical sensitivity and specificity of the assay were evaluated. Samples collected from 229 malaria suspected patients recruited from Sabah, Malaysia were screened using the assay and results were compared with data obtained using PlasmoNex(TM), a hexaplex PCR system. The qRT-PCR-HRM assay was able to detect and discriminate the five Plasmodium spp. with lowest detection limits of 1-100 copy numbers without nonspecific amplifications. The detection of Plasmodium spp. in clinical samples using this assay also achieved 100% concordance with that obtained using PlasmoNex(TM). This indicated that the diagnostic sensitivity and specificity of this assay in Plasmodium spp. detection is comparable with those of PlasmoNex(TM). The qRT-PCR-HRM assay is simple, produces results in two hours and enables high-throughput screening. Thus, it is an alternative method for rapid and accurate malaria diagnosis.
  16. Lim SC, Yap YC, Barmania S, Govender V, Danhoundo G, Remme M
    Sex Reprod Health Matters, 2020 Dec;28(2):1842153.
    PMID: 33236973 DOI: 10.1080/26410397.2020.1842153
    Despite increasing calls to integrate and prioritise sexual and reproductive health (SRH) services in universal health coverage (UHC) processes, several SRH services have remained a low priority in countries' UHC plans. This study aims to understand the priority-setting process of SRH interventions in the context of UHC, drawing on the Malaysian experience. A realist evaluation framework was adopted to examine the priority-setting process for three SRH tracer interventions: pregnancy, safe delivery and post-natal care; gender-based violence (GBV) services; and abortion-related services. The study used a qualitative multi-method design, including a literature and document review, and 20 in-depth key informant interviews, to explore the context-mechanism-outcome configurations that influenced and explained the priority-setting process. Four key advocacy strategies were identified for the effective prioritisation of SRH services, namely: (1) generating public demand and social support, (2) linking SRH issues with public agendas or international commitments, (3) engaging champions that are internal and external to the public health sector, and (4) reframing SRH issues as public health issues. While these strategies successfully triggered mechanisms, such as mutual understanding and increased buy-in of policymakers to prioritise SRH services, the level and extent of prioritisation was affected by both inner and outer contextual factors, in particular the socio-cultural and political context. Priority-setting is a political decision-making process that reflects societal values and norms. Efforts to integrate SRH services in UHC processes need both to make technical arguments and to find strategies to overcome barriers related to societal values (including certain socio-cultural and religious norms). This is particularly important for sensitive SRH services, like GBV and safe abortion, and for certain populations.
  17. Low SK, Khoo JK, Tavintharan S, Lim SC, Sum CF
    Ann Acad Med Singap, 2016 Jan;45(1):1-5.
    PMID: 27118222
  18. Khoo W, Chung SM, Lim SC, Low CY, Shapiro JM, Koh CT
    Data Brief, 2019 Dec;27:104718.
    PMID: 31763388 DOI: 10.1016/j.dib.2019.104718
    Data in this article are supplementary to the corresponding research article [1]. Morphological features of homogeneous and graded nanofibrous electrospun gelatin scaffolds were observed using scanning electron microscopy. Microstructural properties including fiber diameter and pore size were determined via image analysis, using ImageJ. Uniaxial tensile and fracture tests were performed on both homogeneous and graded scaffolds using a universal testing machine. Stress-strain curves of all scaffolds are presented. Computing software, MATLAB, was used to design fibrous networks with thickness-dependent density and alignment gradients (DAG). Finite element analysis software, Abaqus, was used to determine the effect of the number of layers on the fracture properties of DAG multilayer scaffolds.
  19. Tan DT, Siri JG, Gong Y, Ong B, Lim SC, MacGillivray BH, et al.
    Global Health, 2019 12 18;15(1):85.
    PMID: 31847865 DOI: 10.1186/s12992-019-0527-1
    BACKGROUND: Localisation is a pervasive challenge in achieving sustainable development. Contextual particularities may render generalized strategies to achieve the Sustainable Development Goals (SDGs) unfeasible, impractical, or ineffective. Furthermore, many localities are resource- and data-poor, limiting applicability of the global SDG indicator framework. Tools to enable local actors to make sense of complex problems, communicate this understanding, and act accordingly hold promise in their ability to improve results.

    AIM: Systems approaches can help characterise local causal systems, identify useful leverage points, and foster participation needed to localise and catalyse development action. Critically, such efforts must be deeply rooted in place, involving local actors in mapping decision-processes and causation within local physical, social and policy environments. Given that each place has a unique geographical or spatial extent and therein lies its unique characters and problems, we term these activities "placially explicit." We describe and reflect on a process used to develop placially explicit, systems-based (PESB) case studies on issues that intersect with and impact urban health and wellbeing, addressing the perspectives of various actors to produce place-based models and insights that are useful for SDG localisation.

    METHODS: Seven case studies were co-produced by one or more Partners with place-based knowledge of the case study issue and a Systems Thinker. In each case, joint delineation of an appropriate framing was followed by iterative dialogue cycles to uncover key contextual factors, with attention to institutional and societal structures and paradigms and the motivations and constraints of other actors. Casual loop diagrams (CLDs) were iteratively developed to capture complex narratives in a simple visual way.

    RESULTS: Case study development facilitated transfer of local knowledge and development of systems thinking capacity. Partners reported new insights, including a shifting of problem frames and corresponding solution spaces to higher systems levels. Such changes led partners to re-evaluate their roles and goals, and thence to new actions and strategies. CLD-based narratives also proved useful in ongoing communications.

    CONCLUSION: Co-production of PESB case studies are a useful component of transdisciplinary toolsets for local SDG implementation, building the capacity of local actors to explore complex problems, identify new solutions and indicators, and understand the systemic linkages inherent in SDG actions across sectors and scales.

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