Displaying publications 281 - 300 of 9921 in total

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  1. Suid MH, Ahmad MA
    ISA Trans, 2021 Dec 16.
    PMID: 34991880 DOI: 10.1016/j.isatra.2021.11.037
    Automatic Voltage Regulator (AVR) is fabricated to sustain the voltage level of a synchronous generator spontaneously. Several control strategies have been introduced into the AVR system with the aim of gaining a better dynamic response. One of the most universally utilized controllers is the Proportional-Integral-Derivative (PID) controller. Despite the PID controller having a relatively high dynamic response, there are still further possibilities to improve in order to obtain more appropriate responses. This paper designed a sigmoid-based PID (SPID) controller for the AVR system in order to allow for an accelerated settling to rated voltage, as well as increasing the control accuracy. In addition, the parameters of the proposed SPID controller are obtained using an enhanced self-tuning heuristic optimization method called Nonlinear Sine Cosine Algorithm (NSCA), for achieving a better dynamic response, particularly with regards to the steady-state errors and overshoot of the system. A time-response specifications index is used to validate the proposed SPID controller. The obtained simulation results revealed that the proposed method was not only highly effective but also greatly improved the AVR system transient response in comparison to those with the modern heuristic optimization based PID controllers.
  2. Aftab SMA, Ahmad KA
    PLoS One, 2017;12(8):e0183456.
    PMID: 28850622 DOI: 10.1371/journal.pone.0183456
    The Humpback whale tubercles have been studied for more than a decade. Tubercle Leading Edge (TLE) effectively reduces the separation bubble size and helps in delaying stall. They are very effective in case of low Reynolds number flows. The current Computational Fluid Dynamics (CFD) study is on NACA 4415 airfoil, at a Reynolds number 120,000. Two TLE shapes are tested on NACA 4415 airfoil. The tubercle designs implemented on the airfoil are sinusoidal and spherical. A parametric study is also carried out considering three amplitudes (0.025c, 0.05c and 0.075c), the wavelength (0.25c) is fixed. Structured mesh is utilized to generate grid and Transition SST turbulence model is used to capture the flow physics. Results clearly show spherical tubercles outperform sinusoidal tubercles. Furthermore experimental study considering spherical TLE is carried out at Reynolds number 200,000. The experimental results show that spherical TLE improve performance compared to clean airfoil.
  3. Suah FBM, Ahmad M
    Anal Chim Acta, 2017 Jan 25;951:133-139.
    PMID: 27998481 DOI: 10.1016/j.aca.2016.11.040
    The use of a polymer inclusion membrane (PIM) as a sensing material is a new approach to overcome the selectivity and stability drawbacks of the optical chemical sensor (optode). In this study, non-plasticized PIM containing poly(vinyl chloride) as a support base, sodium morin-5-sulfonate (NaMSA) as a reagent and Aliquat 336 as a fixed carrier (ionophore) was prepared and its performance was tested for application in an optode to determine Al3+ ions. The results showed that PIM properties are greatly influenced by the membrane composition. The studies revealed that the optode response was dependent on film thickness, the presence of plasticizer, stirring effect, concentration of NaMSA, concentration of Aliquat 336 and pH of the aqueous solution used. The dynamic range of Al3+ ions concentration determined using this optode was linear from 5.19 × 10-7 to 6.00 × 10-5 mol L-1 and the calculated limit of detection (L.O.D.) was found to be 4.07 × 10-7 mol L-1. The maximum emission wavelength (λem) for the PIM based optode was 512 nm. Scanning electron microscopy analysis of the PIM revealed that a dense texture was formed. Fourier transform infra-red and thermal gravimetry analysis characterizations proved that all of the constituents of the PIM remain within the membrane. The PIM developed in this work was found to be stable, has good mechanical strength, and is sensitive and reusable. Lastly, the PIM was successfully applied as an optical sensor for determination of Al3+ ions in an aqueous solution.
  4. Zhao L, Yang L, Ahmad K
    Hum Exp Toxicol, 2023;42:9603271221146780.
    PMID: 36607234 DOI: 10.1177/09603271221146780
    OBJECTIVES: Kaempferol (KMF), has beneficial effects against hepatic lipid accumulation. In this study, we aimed to investigate molecular mechanism underlying the protective effect of KMF on lipid accumulation.

    METHODS: HepG2 cells were treated with different concentrations of KMF and 0.5 mM palmitate (PA) for 24  h. The mRNA and protein levels of genes involved in lipid metabolism were evaluated using real-time PCR and western blot. The expression of Nrf2 was silenced using siRNA.

    RESULTS: Data indicated that KMF (20 μM) reversed PA-induced increased triglyceride (TG) levels and total lipid content. These effects were accompanied by down-regulation of the mRNA and protein levels of lipogenic genes (FAS, ACC and SREBP1), and up-regulation of genes related to fatty acid oxidation (CPT-1, HADHα and PPARα). Kaempferol significantly decreased the levels of the oxidative stress markers (ROS and MDA) and enhanced the activities of antioxidant enzymes SOD and GPx in PA-challenged cells. Luciferase analysis showed that KMF increased the transactivation of Nrf2 in hepatocytes. The results also revealed that KMF-mediated activation of Nrf2 target genes was suppressed by Nrf2 siRNA. Furthermore, Nrf2 siRNA abolished the KMF-induced reduction in ROS and MDA levels in PA treated cells. In addition, the inhibitory effect of KMF on TG levels and the mRNA and protein levels of FAS, ACC and SREPB-1 were significantly abolished by Nrf2 inhibition. Nrf2 inhibition also suppressed the KMF-induced activation of genes involved in β oxidation (CPT-1 and PPAR-α).

    CONCLUSION: The results suggest that KMF protects HepG2 cells from PA-induced lipid accumulation via activation of the Nrf2 signaling pathway.

  5. Zainudin MF, Ahmad Fauzi A
    J Spinal Cord Med, 2023 Jan;46(1):91-98.
    PMID: 34292138 DOI: 10.1080/10790268.2021.1950454
    OBJECTIVE: To identify factors that are associated with sports participation following spinal cord injury (SCI).

    STUDY DESIGN: Case-control study.

    SETTING: Spinal Rehabilitation outpatient clinic in a tertiary hospital in Kuala Lumpur, Malaysia.

    PARTICIPANTS: Thirty-one sports participants (SP) and thirty-four non-sports participants (NSP) (N = 65) met the following inclusion criteria; chronic SCI more than one year, age between 18 and 50 years, both traumatic and non-traumatic SCI at C5 level and below, complete or incomplete SCI (AIS A-D) and mobilizing with either manual or motorized wheelchair independently.

    METHODS: Face-to-face interviews were performed with a 22-item self-constructed questionnaire which contained four domains of variables; socio-demographic, SCI-related, environmental and sports-related factors. Data collection was done between June 2017 and May 2018.

    RESULTS: Traumatic SCI, pre-injury interest in sports, pre-injury sports participation, ability to drive own vehicles, and being employed were significantly associated with sports participation post-SCI (p 

  6. Gohari A, Gohari A, Ahmad AB
    Environ Sci Pollut Res Int, 2023 Jan;30(2):3707-3725.
    PMID: 35953748 DOI: 10.1007/s11356-022-22472-4
    Megacities recently are experiencing a shortage of green spaces basically due to the rapid growth of urbanization and increasing demand for different building types. Consideration of sustainable urban development is essential since the expansion of city facilities should be in line with social, economic, and environmental aspects. In this regard, green roof technology has been recommended as an effective solution for the growth of green spaces per capita and improving sustainability means of urban developments due to its diverse advantages. This study thus aimed at prioritizing sustainability indicators and relative sub-criteria of adopting green roof technology for residential and governmental buildings in the city of Mashhad, Iran, which has a dry climate. For this purpose, thirteen sub-criteria, which are extracted from the existing literature, are classified into three main sustainability indicators (environmental, economic, and social). Also, the best-worth method (BWM) as a multi-criteria decision-making technique was implemented to prioritize indicators and sub-criteria by analyzing the expert's opinion. The results indicated that respective economic and environmental indicators attract the highest priority in residential and governmental buildings. Additionally, the most important sub-criteria in environmental, economic, and social groups are air quality, roof longevity, and public health in both building types, respectively. However, when all criteria were considered, the respective highest priorities belong to roof longevity and air quality in residential and governmental buildings, while biodiversity conservation is the least important one in both building types. The results of this research can be beneficial in other cities with similar economic and climate conditions.
  7. Gueffier X, Lalonde D, Ahmad AA
    Trauma Case Rep, 2021 Apr;32:100446.
    PMID: 33732858 DOI: 10.1016/j.tcr.2021.100446
    A feature of the flexor pollicis longus tendon injury is the frequency of palmar retraction so that a wrist approach is needed for retrieval of the proximal stump. We are reporting on our first outpatient zone T2 flexor pollicis longus tendon repair under WALANT with ultrasound guidance. In the event of zone T2 flexor pollicis rupture, ultrasound location of tendon extremities is used to plan surgical WALANT strategy and to guide the injection of lidocaine with epinephrine whilst limiting the injected volume to what is strictly necessary.
  8. Quadri MFA, Ahmad B
    Int J Paediatr Dent, 2023 Jul;33(4):394-408.
    PMID: 36825995 DOI: 10.1111/ipd.13060
    BACKGROUND: The evidence for the impact of oral health on academic performance is still unclear.

    AIM: To assess the impact of oral health conditions on poor academic performance in schoolchildren by including a range of clinical and self-reported OH measures in a modified cross-sectional study.

    DESIGN: This study was carried out on schoolchildren aged 12-14 years in Jazan, Saudi Arabia, using a stratified and randomised cluster sampling method. Clinical indices from oral screening and self-reported OH conditions and behaviours and school absence from the self-administered questionnaire were recorded a month before the school examination. Results of passing or failing the examination were obtained after the examination. Statistical associations were examined using bivariate and multiple logistic regressions. The oral health measures were categorised based on the types of conditions and briefly appraised.

    RESULTS: Measures of dental caries, dental pain, soft tissue problems, oral hygiene, tooth discolouration, tooth mobility and school absence due to dental pain were associated with greater odds of failing the examination (p 

  9. Ahmad Bahathig A, Abu Saad H
    Int J Environ Res Public Health, 2022 Sep 08;19(18).
    PMID: 36141585 DOI: 10.3390/ijerph191811314
    This cluster-randomized study aimed to evaluate the effects of an intervention focused on physical activity, nutrition, and body image perception among girls in intermediate schools in Saudi Arabia. A seminar was delivered to the mothers of the girls in the experimental group. The experimental group then attended six interactive sessions within 3 months featuring physical activity, nutrition, and body image perception, followed by a 3-month follow-up period. A total of 138 respondents (68 in the experimental group and 70 in the control group) completed the intervention. Each participant's body mass index-for-age z-score and waist circumference were measured, and they completed a physical activity, sedentary behavior, and body image perception questionnaires before and after the intervention and at the follow-up. The intervention was evaluated using within- and between-groups generalized estimating equations. There were no significant changes in the respondents' body mass index-for-age z-score or waist circumference (p > 0.05). However, immediate significant improvements were seen in physical activity, sedentary behavior, and body image satisfaction among the experimental group, and these improvements remained at follow-up (p < 0.001). These differences were more significant among the experimental group than among the control group. We found this intervention effective. Future studies can adapt this intervention for adolescent boys and extend its duration to improve the body mass index outcome.
  10. Aqmal-Naser M, Ahmad AB
    Trop Life Sci Res, 2024 Jul;35(2):309-317.
    PMID: 39234472 DOI: 10.21315/tlsr2024.35.2.15
    Neotropical cichlid possesses territorial aggression which explains their success as alien species that pose threats to local fauna. The feeding ecology of Midas cichlid, Amphilophus citrinellus species outside its native range had never been fully understood. We aim to determine the stomach content, length-weight relationship and condition factor of this non-native species in one of the agroecosystems in Malaysia. The fish was collected using a cast net, and the guts were dissected. The stomach content (n = 35) revealed Midas cichlids feed on a wide array of preys including fish, amphibian and gastropod. The b-value is 2.60 (negative allometric growth) and the relative condition factor, Kn is 1.04. This result represents an initial study on the feeding aspect of this cichlid. Subsequent and continued researches are needed to evaluate the feeding behaviour and prey preferences of this species in its introduced range.
  11. Quadri MFA, Ahmad B
    Caries Res, 2024 Aug 13.
    PMID: 39137743 DOI: 10.1159/000540883
    INTRODUCTION: There is little discussion in the literature on the pathway linking oral health problems and academic performance (AP) in children. This study investigated the hypothesis that the influence of dental caries on academic performance is mediated through toothache and impacted sleep and study activities.

    METHODS: This cross-sectional study on children aged 12-14 years collected data on the exposure (decayed tooth index), outcome (school examination results), and mediator (school absence due to toothache, and oral health impact on sleep and study performances using the Child-Oral Impact on Daily Performance instrument) variables. It used mediation analysis to examine the indirect effects of a single and two serial mediators using model 4 (caries → mediator → AP) and model 6 (caries → mediator 1 → mediator 2 → AP), respectively, in PROCESS macro add-on software in IBM SPSS v24. Analyses were carried out separately for boys and girls at a 5% significance level.

    RESULTS: In model 4, school absence due to toothache (boys: 95% CI: 0.42, 1.01; girls: 95% CI: 0.58, 0.98), and impacted sleep (95% CI: 0.13, 0.41; 95% CI: 2.17, 13.03), and study (95% CI: 0.05, 0.42; 95% CI: 0.54, 0.94) performance were significant single mediators in both sexes. In model 6, school absence due to toothache and impacted sleep activity (boys: 95% CI: 0.02, 0.29 and girls: 95% CI: 1.37, 12.81), and school absence due to toothache and impacted study activity (girls: 95% CI: 1.37, 12.81) were significant two serial-mediators.

    CONCLUSION: This study provides empirical evidence showing that dental caries and toothache can impact academic performance as they disrupt sleep and study performances to influence the learning and cognition process. The finding bridges the understanding of the mechanism underpinning the relationship and thus, further emphasizes the importance of caries prevention in children with high caries risk for improving their health outcomes and educational experience.

  12. Shakeel S, Ahmad Hassali MA
    Malays J Med Sci, 2021 Feb;28(1):109-116.
    PMID: 33679227 DOI: 10.21315/mjms2021.28.1.14
    With the continuation of the second wave of a novel coronavirus disease (COVID-19), which is likely to be even more devastating, there are several associated health problems. COVID-19 is usually mild and non-fatal in children. However, in rare cases, children could severely be affected, and clinical manifestations may differ from adults. A multisystem inflammatory syndrome in children (MIS-C) is a rare but serious complication associated with COVID-19, initiated by an overactive immune response in kids that usually hits weeks after exposure to the COVID-19. MIS-C is a disorder in which inflammation could occur in different parts of the body. The disease puts pressure on the heart, as blood vessels leading towards the heart get inflamed and incapable of carrying adequate blood, hence producing cardiac complications in children hospitalised with MIS-C. The problem seems to be associated with COVID-19 in children; however, the association between MIS-C and COVID-19 is still unidentified. There is very little understanding of what triggers the MIS-C, which necessitates a rigorous mapping of the disease and associated risk elements for better disease management and navigating through this crisis.
  13. Hosseinpour M, Yahaya AS, Sadullah AF
    Accid Anal Prev, 2014 Jan;62:209-22.
    PMID: 24172088 DOI: 10.1016/j.aap.2013.10.001
    Head-on crashes are among the most severe collision types and of great concern to road safety authorities. Therefore, it justifies more efforts to reduce both the frequency and severity of this collision type. To this end, it is necessary to first identify factors associating with the crash occurrence. This can be done by developing crash prediction models that relate crash outcomes to a set of contributing factors. This study intends to identify the factors affecting both the frequency and severity of head-on crashes that occurred on 448 segments of five federal roads in Malaysia. Data on road characteristics and crash history were collected on the study segments during a 4-year period between 2007 and 2010. The frequency of head-on crashes were fitted by developing and comparing seven count-data models including Poisson, standard negative binomial (NB), random-effect negative binomial, hurdle Poisson, hurdle negative binomial, zero-inflated Poisson, and zero-inflated negative binomial models. To model crash severity, a random-effect generalized ordered probit model (REGOPM) was used given a head-on crash had occurred. With respect to the crash frequency, the random-effect negative binomial (RENB) model was found to outperform the other models according to goodness of fit measures. Based on the results of the model, the variables horizontal curvature, terrain type, heavy-vehicle traffic, and access points were found to be positively related to the frequency of head-on crashes, while posted speed limit and shoulder width decreased the crash frequency. With regard to the crash severity, the results of REGOPM showed that horizontal curvature, paved shoulder width, terrain type, and side friction were associated with more severe crashes, whereas land use, access points, and presence of median reduced the probability of severe crashes. Based on the results of this study, some potential countermeasures were proposed to minimize the risk of head-on crashes.
  14. Ahmad R, Abdullah K, Mokhtar L, Fadzil A
    J Med Case Rep, 2009;3:105.
    PMID: 19946583 DOI: 10.1186/1752-1947-3-105
    Tracheal agenesis is a very rare congenital airway anomaly. It may pose a great challenge to the first attending physician both in diagnosis and in establishing the airway during the first day of life.
  15. Biswal BM, Zakaria A, Ahmad NM
    Support Care Cancer, 2003 Apr;11(4):242-8.
    PMID: 12673463
    BACKGROUND: The aim of this study was to evaluate the effect of pure natural honey on radiation-induced mucositis.

    PATIENTS AND METHODS: Forty patients diagnosed with head and neck cancer requiring radiation to the oropharyngeal mucosal area were divided in to two groups to receive either radiation alone or radiation plus topical application of pure natural honey. Patients were treated using a 6-MV linear accelerator at a dose rate of 2 Gy per day five times a week up to a dose of 60-70 Gy. In the study arm, patients were advised to take 20 ml of pure honey 15 min before, 15 min after and 6 h post-radiation therapy. Patients were evaluated every week for the development of radiation mucositis using the Radiation Therapy Oncology Group (RTOG) grading system.

    MAIN RESULTS: There was significant reduction in the symptomatic grade 3/4 mucositis among honey-treated patients compared to controls; i.e. 20% versus 75% ( p 0.00058). The compliance of honey-treated group of patients was better than controls. Fifty-five percent of patients treated with topical honey showed no change or a positive gain in body weight compared to 25% in the control arm ( p 0.053), the majority of whom lost weight.

    CONCLUSIONS: Topical application of natural honey is a simple and cost-effective treatment in radiation mucositis, which warrants further multi-centre randomised trials to validate our finding.

  16. Ramli AT, Rahman AT, Lee MH
    Appl Radiat Isot, 2003 Nov-Dec;59(5-6):393-405.
    PMID: 14622942
    A statistical prediction of terrestrial gamma radiation dose rate has been performed, covering the Kota Tinggi district of Peninsular Malaysia. The prediction has been based on geological features and soil types. The purpose of this study is to provide a methodology to statistically predict the gamma radiation dose rate with minimum surveying in an area. Results of statistical predictions using the hypothesis test were compared with the actual dose rate obtained by measurements.
  17. Zaahirah Mohammad, Norliza Ahmad, Halimatus Sakdiah Minhat
    MyJurnal
    Introduction: Overweight and obesity among adults, especially young adults have been increasing for the past 20 years and is an emerging public health concern all over the world, including Malaysia. This study aims to explore the determinants of overweight and obesity among undergraduate students residing in Universiti Putra Malaysia. Methods: A cross-sectional study using random sampling was conducted in three residential colleges. Independent variables include socio-demographic factors, knowledge on physical activity and dietary intake, lifestyle (physical activity, dietary intake, sleep duration and quality and smoking status) and stress. Data was collected using a vali-dated and reliable self-administered questionnaire and anthropometric measurement (weight and height were mea-sured to determine body mass index). IBM Statistical Package for Social Science (SPSS) version 23 was used for data analysis. Multiple logistic regression was employed to find the determinants of overweight and obesity among the respondents. Significant level was set at less than 0.05. Results: A total of 494 respondents participated with 98.8% response rate. Overweight and obesity prevalence among the respondents was 38.1% with 22.9% and 15.9% of the respondents were overweight and obese respectively. The significant associated factors were age group of 24 years and above (AOR=2.671, p=0.04), male (AOR=1.818, p=0.04), Malay ethnicity (AOR=5.34, p=0.008) and Indian ethnicity (AOR=7.155, p = 0.018). Conclusion: Overweight and obesity prevalence among undergraduate students were more than one third. Programmes and policies should be directed to these high-risk groups as identified in this study.
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