Publications by authors named "Ahmad Ramli"

27 Publications

  • Page 1 of 1

Embarking to Caregiving Role: A Thematic Analysis of Malay Caregivers of Older Adults with Mental Health Problems Perspectives.

J Gerontol Soc Work 2021 Apr 12:1-19. Epub 2021 Apr 12.

School of Nursing, Midwifery and Social Work, University of Queensland, Brisbane, Australia.

Religion and culture affect the meaning and practicalities of caring for families with mental illness in Malaysia. Such care also differs according to social background, family values and support, commitment, availability, practicality and the needs of the care recipient. This qualitative study explores 14 Malay caregivers of the older adults with mental health problems in Kelantan, Malaysia. A semi-structured interview was translated and transcribed and subjected to thematic analysis using NVivo software. The findings show that cultural values and religion shaped the meaning of care as provided by the caregivers. The nature of the relationship is also important in determining the best person in the family to take over the caregiving role.
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http://dx.doi.org/10.1080/01634372.2021.1912240DOI Listing
April 2021

Ultrasound-guided combined supraclavicular brachial plexus and PECS II blocks for brachiobasilic fistula transposition surgery.

Indian J Anaesth 2020 Dec 12;64(12):1079-1080. Epub 2020 Dec 12.

Department of Surgery, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.

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http://dx.doi.org/10.4103/ija.IJA_535_20DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7852432PMC
December 2020

A Rare Case of Purulent Pericardial TB.

Cureus 2019 Aug 9;11(8):e5356. Epub 2019 Aug 9.

Cardiology, Universiti Sultan Zainal Abidin, Terengganu, MYS.

Pericardial effusion is a common disease and tuberculosis (TB) accounts up to 4% of acute pericarditis with up to 7% of tamponade case. Accurate diagnosis is important while quick intervention can be life-saving. A case was reported involving a 73-year-old man who presented with reduced effort tolerance for one-month duration. During hospitalization, further workup revealed the presence of massive purulent pericardial effusion with evidence of tamponade. TB gene expert was positive in aspirated pericardial fluid and the patient was treated promptly using a combination of anti-TB drugs with the addition of steroid therapy.
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http://dx.doi.org/10.7759/cureus.5356DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6783221PMC
August 2019

Geological influence on the activity concentration of terrestrial radionuclides Ra, Th and K in the Jos Plateau, Nigeria.

Isotopes Environ Health Stud 2018 Oct 30;54(5):522-534. Epub 2018 May 30.

c Department of Physics , Yobe State University Damaturu , Damaturu , Nigeria.

The Jos Plateau has been reported to have elevated levels of natural background radiation. A few earlier studies have measured the levels of natural radioactivity for specific locations in the area. Our interest is to investigate how geology of the study area influences the activity concentrations of natural radionuclides. Thus, the activity concentrations of terrestrial radionuclides in soil samples collected across the geological formations of the Jos Plateau were determined by gamma spectrometry technique. The mean activity concentrations of Ra, Th and K were found to exceed their corresponding world reference values of 35, 40 and 400 Bq kg, respectively. Data were compared using statistical methods, analysis of variance (ANOVA) and post hoc tests. The results revealed in some instances significant influences of geological types on the activity concentrations in the area. The spatial distribution maps of activity concentrations of Ra, Th and K were geostatistically interpolated by ordinary Kriging method using ArcGIS software.
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http://dx.doi.org/10.1080/10256016.2018.1474879DOI Listing
October 2018

Secondary prevention of recurrent venous thromboembolism after initial oral anticoagulation therapy in patients with unprovoked venous thromboembolism.

Cochrane Database Syst Rev 2017 12 15;12:CD011088. Epub 2017 Dec 15.

Department of Vascular Surgery, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, High Heaton, Newcastle upon Tyne, UK, NE7 7DN.

Background: Currently, little evidence is available on the length and type of anticoagulation used for extended treatment for prevention of recurrent venous thromboembolism (VTE) in patients with unprovoked VTE who have completed initial oral anticoagulation therapy.

Objectives: To compare the efficacy and safety of available oral therapeutic options (aspirin, warfarin, direct oral anticoagulants (DOACs)) for extended thromboprophylaxis in adults with a first unprovoked VTE, to prevent VTE recurrence after completion of an acceptable initial oral anticoagulant treatment period, as defined in individual studies.

Search Methods: For this review, the Cochrane Vascular Information Specialist (CIS) searched the Specialised Register (March 2017) as well as the Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2). We also searched trials registries (March 2017) and reference lists of relevant articles.

Selection Criteria: We included randomised controlled trials in which patients with a first, symptomatic, objectively confirmed, unprovoked VTE, who had been initially treated with anticoagulants, were randomised to extended prophylaxis (vitamin K antagonists (VKAs), antiplatelet agents, or DOACs) versus no prophylaxis or placebo. We also included trials that compared one type of extended prophylaxis versus another type of extended prophylaxis.

Data Collection And Analysis: Two review authors independently selected studies, assessed quality, and extracted data. We resolved disagreements by discussion.

Main Results: Six studies with a combined total of 3436 participants met the inclusion criteria. Five studies compared extended prophylaxis versus placebo: three compared warfarin versus placebo, and two compared aspirin versus placebo. One study compared one type of extended prophylaxis (rivaroxaban) versus another type of extended prophylaxis (aspirin). For extended prophylaxis versus placebo, we downgraded the quality of the evidence for recurrent VTE and all-cause mortality to moderate owing to concerns arising from risks of selection and performance bias in individual studies. For all other outcomes in this review, we downgraded the quality of the evidence to low owing to concerns arising from risk of bias for the studies stated above, combined with concerns over imprecision. For extended prophylaxis versus other extended prophylaxis, we downgraded the quality of the evidence for recurrent VTE and major bleeding to moderate owing to concerns over imprecision. Risk of bias in the individual study was low.Meta-analysis showed that extended prophylaxis was no more effective than placebo in preventing VTE-related mortality (odds ratio (OR) 0.98, 95% confidence interval (CI) 0.14 to 6.98; 1862 participants; 4 studies; P = 0.98; low-quality evidence), recurrent VTE (OR 0.63, 95% CI 0.38 to 1.03; 2043 participants; 5 studies; P = 0.07; moderate-quality evidence), major bleeding (OR 1.84, 95% CI 0.87 to 3.85; 2043 participants; 5 studies; P = 0.86; low-quality evidence), all-cause mortality (OR 1.00, 95% CI 0.63 to 1.57; 2043 participants; 5 studies; P = 0.99; moderate-quality evidence), clinically relevant non-major bleeding (OR 1.78, 95% CI 0.59 to 5.33; 1672 participants; 4 studies; P = 0.30; low-quality evidence), stroke (OR 1.15, 95% CI 0.39 to 3.46; 1224 participants; 2 studies; P = 0.80; low-quality evidence), or myocardial infarction (OR 1.00, 95% CI 0.35 to 2.87; 1495 participants; 3 studies; P = 1.00; low-quality evidence).One study showed that the novel oral anticoagulant rivaroxaban was associated with fewer recurrent VTEs than aspirin (OR 0.28, 95% CI 0.15 to 0.54; 1389 participants; P = 0.0001; moderate-quality evidence). Data show no clear differences in the incidence of major bleeding between rivaroxaban and aspirin (OR 3.06, 95% CI 0.37 to 25.51; 1389 participants; P = 0.30; moderate-quality evidence) nor in the incidence of clinically relevant non-major bleeding (OR 0.84, 95% CI 0.37 to 1.94; 1389 participants; 1 study; P = 0.69; moderate-quality evidence). Data on VTE-related mortality, all-cause mortality, stroke, and myocardial infarction were not yet available for participants with unprovoked VTE and will be incorporated in future versions of the review.

Authors' Conclusions: Evidence is currently insufficient to permit definitive conclusions concerning the effectiveness and safety of extended thromboprophylaxis in prevention of recurrent VTE after initial oral anticoagulation therapy among participants with unprovoked VTE. Additional good-quality large-scale randomised controlled trials are required before firm conclusions can be reached.
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http://dx.doi.org/10.1002/14651858.CD011088.pub2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6486093PMC
December 2017

Celiac and Superior/Inferior Mesenteric Angioplasty and Stenting for Chronic Mesenteric Ischemia: A Single-Center Experience.

Angiology 2017 Aug 18;68(7):571-574. Epub 2016 Aug 18.

1 Department of Vascular Surgery, Northern Vascular Center, Freeman Hospital, Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle upon Tyne, United Kingdom.

Angioplasty and stenting emerged as the less invasive treatment options compared to open surgical revascularization for the management of patients with chronic mesenteric ischemia (CMI). However, endovascular techniques may not achieve symptomatic relief in many patients with CMI. We report our results from the endovascular management of patients with CMI. Data were reviewed from 45 patients undergoing celiac and/or mesenteric angioplasty and stenting for CMI, from October 2006 to January 2016. Angioplasty and stenting of celiac and/or mesenteric arteries were successful in relieving symptoms completely in 29 of 45 and partially in 6 of 45 patients. Only 10 of 45 patients mentioned no improvement, while symptom recurrence occurred in another 3 of 45 patients between 3 and 36 months postprocedurally due to stent occlusion. Angioplasty and stenting of celiac and/or mesenteric arteries provide symptomatic relief in a considerable percentage of patients with CMI. If symptoms fail to improve, an open surgical revascularization procedure should be considered.
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http://dx.doi.org/10.1177/0003319716662424DOI Listing
August 2017

Point Set Denoising Using Bootstrap-Based Radial Basis Function.

PLoS One 2016 17;11(6):e0156724. Epub 2016 Jun 17.

School of Mathematical Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.

This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0156724PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4912139PMC
July 2017

Natural radioactivity measurements in Pahang State, Malaysia.

Isotopes Environ Health Stud 2016 Jun 21;52(3):298-308. Epub 2016 Mar 21.

a Department of Physics, Faculty of Science , Universiti Teknologi Malaysia , Johor , Malaysia.

This study was aimed at providing the baseline data of terrestrial gamma dose rates and natural radioactivity to assess the corresponding health risk in the ambient environment of the Pahang State. Terrestrial gamma radiation (TGR) from 640 locations was measured with the mean value found to be 176 ± 5 nGy h(-1). Ninety-eight soil samples were analysed using a high-purity germanium detector (HPGe), and the mean concentrations of the radionuclides (226)Ra, (232)Th and (40)K are 110 ± 3, 151 ± 5 and 542 ± 51 Bq kg(-1), respectively.(226)Ra and (232)Th concentrations were found to be three times the world average, while that of (40)K is quite higher than the world average value. The acid-intrusive geological formation has the highest mean concentrations for (226)Ra (215 ± 6 Bq kg(-1)), (232)Th (384 ± 12 Bq kg(-1)) and (40)K (1564 ± 153 Bq kg(-1)). The radium equivalent activities (Req) and the external hazard index (Hex) for the various soil types were also calculated. Some of the soil types were found to have values exceeding the internationally recommended levels of 370 Bq kg(-1) and the unity value, respectively.
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http://dx.doi.org/10.1080/10256016.2016.1128428DOI Listing
June 2016

Terrestrial gamma dose rate, radioactivity and radiological hazards in the rocks of an elevated radiation background in Juban District, Ad Dali' Governorate, Yemen.

J Radiol Prot 2016 Mar 24;36(1):163-77. Epub 2016 Feb 24.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johore Bahru, Johore, Malaysia. National Atomic Energy Commission (NATEC), Sana'a, Yemen.

This study aims to evaluate natural radiation and radioactivity in the rock and to assess the corresponding health risk in a region of elevated background radiation in Juban District, Ad Dali' Governorate, Yemen. The mean external gamma dose rate was 374 nGy h(-1) which is approximately six times the world average. The measured results were used to compute annual effective dose equivalent, collective effective dose and excess lifetime cancer risk, which are 2.298 mSv, 61.95 man Sv y(-1) and 8.043  ×  10(-3), respectively. Rocks samples from different geological formations were analyzed for quantitative determination of (226)Ra, (232)Th and (40)K. The specific activity of the rocks samples ranges from 7  ±  1 Bq Kg(-1) to 12 513  ±  329 Bq Kg(-1) for (232)Th, from 6  ±  1 Bq kg(-1) to 3089  ±  74 Bq kg(-1) for (226)Ra and 702  ±  69 Bq kg(-1) to 2954  ±  285 Bq kg(-1) for (40)K. (232)Th is the main contributor to gamma dose rate from the rock samples. Indicators of radiological health impact, radium equivalent activity and external hazard index are 3738 Bq kg(-1) and 10.10, respectively. The mean external hazard index was ten times unity in the studied locations in Juban District, which is higher than the recommended value.
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http://dx.doi.org/10.1088/0952-4746/36/1/163DOI Listing
March 2016

Radiological mapping of Kelantan, Malaysia, using terrestrial radiation dose rate.

Isotopes Environ Health Stud 2016 Jun 5;52(3):214-8. Epub 2015 Nov 5.

a Department of Physics, Faculty of Science , Universiti Teknologi Malaysia , Johor Bahru, Johor , Malaysia.

Measurements of the environmental terrestrial gamma radiation dose rate (TGRD) in each district of Kelantan state, Malaysia, were carried out using a portable hand-held radiation survey meter and global positioning system. The measurements were done based on geology and soil types of the area. The mean TGRD was found to be 209 nGy h(-1). Few areas of relatively enhanced activity were observed in Pasir Mas, Tanah Merah and Jeli districts, which have a mean TGRD between 300 and 500 nGy h(-1). An isodose map of the area was produced using ArcGIS software version 9.3.
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http://dx.doi.org/10.1080/10256016.2016.1095189DOI Listing
June 2016

An overview of current knowledge concerning the health and environmental consequences of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident.

Environ Int 2015 Dec 29;85:213-28. Epub 2015 Sep 29.

Department of Physics, Universiti Teknologi Malaysia, 81310 Johor Baru, Malaysia.

Since 2011, the scientific community has worked to identify the exact transport and deposition patterns of radionuclides released from the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan. Nevertheless, there still remain many unknowns concerning the health and environmental impacts of these radionuclides. The present paper reviews the current understanding of the FDNPP accident with respect to interactions of the released radionuclides with the environment and impacts on human and non-human biota. Here, we scrutinize existing literature and combine and interpret observations and modeling assessments derived after Fukushima. Finally, we discuss the behavior and applications of radionuclides that might be used as tracers of environmental processes. This review focuses on (137)Cs and (131)I releases derived from Fukushima. Published estimates suggest total release amounts of 12-36.7PBq of (137)Cs and 150-160PBq of (131)I. Maximum estimated human mortality due to the Fukushima nuclear accident is 10,000 (due to all causes) and the maximum estimates for lifetime cancer mortality and morbidity are 1500 and 1800, respectively. Studies of plants and animals in the forests of Fukushima have recorded a range of physiological, developmental, morphological, and behavioral consequences of exposure to radioactivity. Some of the effects observed in the exposed populations include the following: hematological aberrations in Fukushima monkeys; genetic, developmental and morphological aberrations in a butterfly; declines in abundances of birds, butterflies and cicadas; aberrant growth forms in trees; and morphological abnormalities in aphids. These findings are discussed from the perspective of conservation biology.
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http://dx.doi.org/10.1016/j.envint.2015.09.020DOI Listing
December 2015

Prediction of terrestrial gamma dose rate based on geological formations and soil types in the Johor State, Malaysia.

J Environ Radioact 2015 Oct 3;148:111-22. Epub 2015 Jul 3.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johore Bahru, Johore, Malaysia.

This study aims to predict and estimate unmeasured terrestrial gamma dose rate (TGDR) using statistical analysis methods to derive a model from the actual measurement based on geological formation and soil type. The measurements of TGDR were conducted in the state of Johor with a total of 3873 measured points which covered all geological formations, soil types and districts. The measurements were taken 1 m above the soil surface using NaI [Ti] detector. The measured gamma dose rates ranged from 9 nGy h(-1) to 1237 nGy h(-1) with a mean value of 151 nGy h(-1). The data have been normalized to fit a normal distribution. Tests of significance were conducted among all geological formations and soil types, using the unbalanced one way ANOVA. The results indicated strong significant differences due to the different geological formations and soil types present in Johor State. Pearson Correlation was used to measure the relations between gamma dose rate based on geological formation and soil type (D(G,S)) with the gamma dose rate based on geological formation (D(G)) or soil type (D(s)). A very good correlation was found between D(G,S) and D(G) or D(G,S) and D(s). A total of 118 pairs of geological formations and soil types were used to derive the statistical contribution of geological formations and soil types to gamma dose rates. The contribution of the gamma dose rate from geological formation and soil type were found to be 0.594 and 0.399, respectively. The null hypotheses were accepted for 83% of examined data, therefore, the model could be used to predict gamma dose rates based on geological formation and soil type information.
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http://dx.doi.org/10.1016/j.jenvrad.2015.05.019DOI Listing
October 2015

Radioecological impacts of tin mining.

Ambio 2015 Dec 21;44(8):778-87. Epub 2015 Jun 21.

Department of Urban and Regional Planning, Universiti Teknologi Malaysia, Johor, Malaysia.

The tin mining activities in the suburbs of Jos, Plateau State, Nigeria, have resulted in technical enhancement of the natural background radiation as well as higher activity concentrations of primordial radionuclides in the topsoil of mining sites and their environs. Several studies have considered the radiological human health risks of the mining activity; however, to our knowledge no documented study has investigated the radiological impacts on biota. Hence, an attempt is made to assess potential hazards using published data from the literature and the ERICA Tool. This paper considers the effects of mining and milling on terrestrial organisms like shrubs, large mammals, small burrowing mammals, birds (duck), arthropods (earth worm), grasses, and herbs. The dose rates and risk quotients to these organisms are computed using conservative values for activity concentrations of natural radionuclides reported in Bitsichi and Bukuru mining areas. The results suggest that grasses, herbs, lichens, bryophytes and shrubs receive total dose rates that are of potential concern. The effects of dose rates to specific indicator species of interest are highlighted and discussed. We conclude that further investigation and proper regulations should be set in place in order to reduce the risk posed by the tin mining activity on biota. This paper also presents a brief overview of the impact of mineral mining on biota based on documented literature for other countries.
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http://dx.doi.org/10.1007/s13280-015-0677-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4646856PMC
December 2015

Health and ecological hazards due to natural radioactivity in soil from mining areas of Nasarawa State, Nigeria.

Isotopes Environ Health Stud 2015 7;51(3):448-68. Epub 2015 Apr 7.

a Department of Physics , Universiti Teknologi Malaysia , Skudai , Johor , Malaysia.

Nasarawa State is located in north central Nigeria and it is known as Nigeria's home of solid minerals. It is endowed with barite, copper, zinc, tantalite and granite. Continuous releases of mining waste and tailings into the biosphere may result in a build-up of radionuclides in air, water and soil. This work therefore aims to measure the activity concentration levels of primordial radionuclides in the soil/sediment samples collected from selected mines of the mining areas of Nasarawa State. The paper also assesses the radiological and radio ecological impacts of mining activities on the residents of mining areas and their environment. The activity concentrations of primordial radionuclides ((226)Ra, (232)Th and (40)K) in the surface soils/sediment samples were determined using sodium iodide-thallium gamma spectroscopy. Seven major mines were considered with 21 samples taken from each of the mines for radiochemistry analysis. The human health hazard assessment was conducted using regulatory methodologies set by the United Nations Scientific Committee on the Effects of Atomic Radiation, while the radio ecological impact assessment was conducted using the ERICA tool v. 1.2. The result shows that the activity concentrations of (40)K in the water ways of the Akiri copper and the Azara barite mines are 60 and 67% higher than the world average value for (40)K, respectively. In all mines, the annual effective dose rates (mSv y(-1)) were less than unity, and a maximum annual gonadal dose of 0.58 mSv y(-1) is received at the Akiri copper mine, which is almost twice the world average value for gonadal dose. The external hazard indices for all the mines were less than unity. Our results also show that mollusc-gastropod, insect larvae, mollusc-bivalve and zooplankton are the freshwater biotas with the highest dose rates ranging from 5 to 7 µGy h(-1). These higher dose rates could be associated with zinc and copper mining at Abuni and Akiri, respectively. The most exposed terrestrial reference organisms are lichen and bryophytes. In all cases, the radio ecological risks are not likely to be discernible. This paper presents a pioneer data for ecological risk from ionizing contaminants due to mining activity in Nasarawa State, Nigeria. Its methodology could be adopted for future work on radioecology of mining.
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http://dx.doi.org/10.1080/10256016.2015.1026339DOI Listing
June 2016

Fukushima nuclear accident: preliminary assessment of the risks to non-human biota.

Radiat Prot Dosimetry 2015 Feb 14;163(2):238-50. Epub 2014 May 14.

Department of Physics, Nasarawa State University, Keffi, Nigeria.

This study assesses the 'radio-ecological' impacts of Fukushima nuclear accident on non-human biota using the ERICA Tool, which adopts an internationally verified methodology. The paper estimates the impacts of the accident on terrestrial and marine biota based on the environmental data reported in literature for Japan, China, South Korea and the USA. Discernible impacts have been detected in the marine biota around Fukushima Daiichi nuclear power plant. This study confirms that the Fukushima accident had caused heavier damage to marine bionts compared with terrestrial flora and fauna, in Japan.
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http://dx.doi.org/10.1093/rpd/ncu158DOI Listing
February 2015

Partitioning of soil phosphorus regulates competition between Vaccinium vitis-idaea and Deschampsia cespitosa.

Ecol Evol 2013 Oct 1;3(12):4243-52. Epub 2013 Oct 1.

Institute of Biological and Environmental Sciences, University of Aberdeen Cruickshank Building, St Machar Drive, Aberdeen, AB24 3UU, UK.

It has been hypothesized that the wide range of forms and complexities of phosphorus (P) in soil may result in resource partitioning that contributes to the maintenance of plant species diversity. Here, we test whether the graminoid, Deschampsia cespitosa, and the ericaceous shrub, Vaccinium vitis-idaea, which often coexist, display preferences in utilization of P forms, and differ in their production of extracellular P-degrading enzymes. We provided plants with no additional P, or P forms with decreasing lability, namely sodium phosphate (SP), D-glucose 6 phosphate (DG6P), sodium phytate (PASS), and a combination of SP, DG6P, and PASS. We also tested if preferences for P forms affected the competitive outcomes between the two species compared between conspecifics, as indicated by shoot biomass and acquisition of nitrogen (N) and P. Both D. cespitosa and V. vitis-idaea produced the greatest biomass when supplied with a mix of all three forms of P. Of the three forms of P tested alone, shoot biomass produced by both species was least when supplied with SP. D. cespitosa performed better when grown with PASS or a mix of all P forms compared with the performance of V. vitis-idaea on these substrates. This was reflected by substantially greater phytase activity on the surface of its roots compared with V. vitis-idaea. In contrast, V. vitis-idaea produced more phosphomonoesterase to hydrolyze the simple organic P form, DG6P. Although N was kept constant in the treatments, the ability of plants to acquire it was dependent on species identity, competition, and P supply. These findings provide direct evidence for preferences toward specific forms of P and indicate a key role played by organic forms of P. The results support the idea that partitioning for soil P is one factor regulating plant competition, and ultimately, community composition. Our data also highlight the importance of the interplay between P supply and N acquisition.
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http://dx.doi.org/10.1002/ece3.771DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3853568PMC
October 2013

A survey of gross alpha and gross beta activity in soil samples in Kinta District, Perak, Malaysia.

Radiat Prot Dosimetry 2014 Dec 8;162(3):345-50. Epub 2013 Nov 8.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310, UTM, Skudai, Johor Bahru, Johor, Malaysia.

The objective of this study was to determine the gross alpha and gross beta activity concentrations from the different soil types found in the Kinta District, Perak, Malaysia. A total of 128 soil samples were collected and their dose rates were measured 1 m above the ground. Gross alpha and gross beta activity measurements were carried out using gas flow proportional counter, Tennelec Series 5 LB5500 Automatic Low Background Counting System. The alpha activity concentration ranged from 15 to 9634 Bq kg(-1) with a mean value of 1558±121 Bq kg(-1). The beta activity concentration ranged from 142 to 6173 Bq kg(-1) with a mean value of 1112±32 Bq kg(-1). High alpha and beta activity concentrations are from the same soil type. The results of the analysis show a strong correlation between the gross alpha activity concentration and dose rate (R = 0.92). The data obtained can be used as a database for each soil type.
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http://dx.doi.org/10.1093/rpd/nct273DOI Listing
December 2014

Luminescence characteristics of Li₂CO₃-K₂CO₃-H₃BO₃ glasses co-doped with TiO₂/MgO.

Appl Radiat Isot 2013 Dec 9;82:12-9. Epub 2013 Jul 9.

Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia; Department of Medical Radiography, Al-Azhar University, Gaza Strip, Palestine. Electronic address:

Understanding the influence of co-dopants in the luminescence enhancement of carbonate glasses is the key issue in dosimetry. A series of borate glasses modified by lithium and potassium carbonate were synthesized by the melt-quenching method. The glass mixture activated with various concentrations of TiO2 and MgO was subjected to various doses of gamma-rays ((60)Co). The amorphous nature of the samples was confirmed by x-ray diffraction (XRD) spectra. The simple glowing curve of the glass doped with TiO2 features a peak at 230°C, whose intensity is maximal at 0.5 mol% of the dopant. The intensity of the glowing curve increases with the concentration of MgO added as a co-dopant up to 0.25 mol%, where it is two times higher than for the material without MgO thermoluminescence properties, including dose response, reproducibility, and fading were studied. The effective atomic number of the material was also determined. Kinetic parameters, such as kinetics order, activation energy, and frequency factor are estimated. The photoluminescence spectra of the titanium-doped glass consist of a prominent peaks at 480 nm when laser excitation at 650 nm is used. A three-fold photoluminescence enhancement and a blue shift of the peak were observed when 0.1% MgO was introduced. In addition, various physical parameters, such as ion concentration, polaron radius and internuclear distances were calculated. The mechanism for the thermoluminescence and photoluminescence enhancements are discussed.
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http://dx.doi.org/10.1016/j.apradiso.2013.07.005DOI Listing
December 2013

Assessment of environmental (226)Ra, (232)Th and (40)K concentrations in the region of elevated radiation background in Segamat District, Johor, Malaysia.

J Environ Radioact 2013 Oct 29;124:130-40. Epub 2013 May 29.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johore Bahru, Johore, Malaysia.

Extensive environmental survey and measurements of gamma radioactivity in the soil samples collected from Segamat District were conducted. Two gamma detectors were used for the measurements of background radiation in the area and the results were used in the computation of the mean external radiation dose rate and mean weighted dose rate, which are 276 nGy h(-1) and 1.169 mSv y(-1), respectively. A high purity germanium (HPGe) detector was used in the assessment of activity concentrations of (232)Th, (226)Ra and (40)K. The results of the gamma spectrometry range from 11 ± 1 to 1210 ± 41 Bq kg(-1) for (232)Th, 12 ± 1 to 968 ± 27 Bq kg(-1) for (226)Ra, and 12 ± 2 to 2450 ± 86 Bq kg(-1) for (40)K. Gross alpha and gross beta activity concentrations range from 170 ± 50 to 4360 ± 170 Bq kg(-1) and 70 ± 20 to 4690 ± 90 Bq kg(-1), respectively. These results were used in the plotting of digital maps (using ARCGIS 9.3) for isodose. The results are compared with values giving in UNSCEAR 2000.
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http://dx.doi.org/10.1016/j.jenvrad.2013.04.013DOI Listing
October 2013

Household survey of container-breeding mosquitoes and climatic factors influencing the prevalence of Aedes aegypti (Diptera: Culicidae) in Makkah City, Saudi Arabia.

Asian Pac J Trop Biomed 2012 Nov;2(11):849-57

Medical Entomology Laboratory, School of Biological Sciences, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.

Objective: To investigate the prevalence of container breeding mosquitoes with emphasis on the seasonality and larval habitats of Aedes aegypti (Ae. aegypti) in Makkah City, adjoining an environmental monitoring and dengue incidence.

Methods: Monthly visits were performed between April 2008 and March 2009 to randomly selected houses. During each visit, mosquito larvae were collected from indoors and outdoors containers by either dipping or pipetting. Mosquitoes were morphologically identified. Data on temperature, relative humidity, rain/precipitations during the survey period was retrieved from governmental sources and analyzed.

Results: The city was warmer in dry season (DS) than wet season (WS). No rain occurred at all during DS and even precipitations did fall, wetting events were much greater during WS. Larval survey revealed the co-breeding of Aedes, Culex and Anopheles in a variety of artificial containers in and around homes. 32 109 larvae representing 1st , 2nd, 3rd, and 4th stages were collected from 22 618 container habitats. Culicines was far the commonest and Aedes genus was as numerous as the Culex population. Ae. aegypti larval abundance exhibited marked temporal variations, overall, being usually more abundant during WS. Ten types of artificial containers were found with developing larvae. 70% of these habitats were located indoors. 71.42% of indoor containers were permanent and 28.58% was semi-permanent during WS. Cement tanks was the only container type permanent during DS. Ae. aegypti larval indices (CI, HI, BI) recorded were greater during WS.

Conclusions: Taken together, these results indicate a high risk of dengue transmission in the holy city.
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http://dx.doi.org/10.1016/S2221-1691(12)60242-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3609246PMC
November 2012

Terrestrial gamma radiation and its statistical relation with geological formation in the Mersing district, Johor, Malaysia.

Radiat Prot Dosimetry 2013 Sep 28;156(2):246-52. Epub 2013 Mar 28.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johor Bahru, Johor, Malaysia.

An extensive survey was carried out for gamma dose rates (GDRs) in the Mersing district, Johor, Malaysia. The average value of GDR measured in the district was found to be 140 nGy h(-1), in the range of 40-355 nGy h(-1). The mean weighted dose rate to the population, annual effective dose equivalent, collective effective dose equivalent, lifetime cancer risk were 0.836 mSv y(-1), 0.171 mSv, 1.18 × 10(1) man Sv y(-1) and 6.98 × 10(-4) Sv y, respectively. An isodose map was produced for the district. One way analysis of variance was used to test for differences due to different geological formations present in the Mersing District.
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http://dx.doi.org/10.1093/rpd/nct061DOI Listing
September 2013

Thermoluminescence properties of Li2CO3-K2CO3-H3BO3glass system co-doped with CuO and MgO.

Radiat Prot Dosimetry 2013 Jun 28;155(1):1-10. Epub 2012 Nov 28.

Department of Physics, Universiti Teknologi Malaysia, Skudai, Johor 81310, Malaysia.

The thermoluminescent properties of boric glass modified with lithium and potassium carbonates (LKB) and co-doped with CuO and MgO are reported for the first time. Two techniques are applied to investigate the effect of dopants and co-dopants on the thermal stimulation properties of LKB. The induced TL glow curves of a CuO-doped sample are found to be at 220°C with a single peak. An enhancement of about three times is shown with the increment of 0.1 mol % MgO as a co-dopant impurity. This enhancement may contribute to the ability of magnesium to create extra electron traps and consequently the energy transfer to monovalent Cu(+) ions. LKB:Cu,Mg is low Z material (Zeff=8.55), and observed 15 times less sensitive than LiF: Mg, Ti (TLD-100). The proposed dosemeter showed good linearity in TL dose-response, low fading and excellent reproducibility with a simple glow curve, and thus, can be used in the radiation dosimetry.
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http://dx.doi.org/10.1093/rpd/ncs310DOI Listing
June 2013

Low-dose photon irradiation response of Ge and Al-doped SiO2 optical fibres.

Appl Radiat Isot 2011 Sep 6;69(9):1189-92. Epub 2011 Apr 6.

Department of Physics, Universiti Teknologi Malaysia, Johor Darul Takzim, Malaysia.

We have investigated the thermoluminescent response and fading characteristics of germanium- and aluminium-doped SiO(2) optical fibres. These optical fibres were placed in a solid phantom and irradiated using 6 and 10 MV photon beams at doses ranging from 0.02 to 0.24 Gy delivered using a linear accelerator. In fading studies, the TL measurements were continued up to 14 days post-irradation. We have investigated the linearity of TL response as a function of dose for Ge-, Al-doped optical fibre and TLD-100 obtained for 6 and 10 MV photon irradiations. We have concentrated on doses that represent a small fraction of that delivered to the tumour to establish sensitivity of measurement for peripheral exposures in external beam radiotherapy.
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http://dx.doi.org/10.1016/j.apradiso.2011.03.039DOI Listing
September 2011

Radiological monitoring: terrestrial natural radionuclides in Kinta District, Perak, Malaysia.

J Environ Radioact 2009 May 19;100(5):368-74. Epub 2009 Mar 19.

Department of Physics, Faculty of Science, University Teknologi Malaysia, 81310 Skudai, Johor Bahru, Malaysia.

Natural background gamma radiation and radioactivity concentrations were investigated from 2003 to 2005 in Kinta District, Perak, Malaysia. Sample locations were distant from any 'amang' processing plants. The external gamma dose rates ranged from 39 to 1039 nGy h(-1). The mean external gamma dose rate was 222+/-191 nG yh(-1). Small areas of relatively enhanced activity were located having external gamma dose rates of up to 1039+/-104 nGy h(-1). The activity concentrations of (238)U, (232)Th and (40)K were analyzed by using a high-resolution co-axial HPGe detector system. The activity concentration ranges were 12-426 Bq kg(-1) for (238)U, 19-1377 Bq kg(-1) for (232)Th and <19-2204 Bq kg(-1) for (40)K. Based on the radioactivity levels determined, the gamma-absorbed dose rates in air at 1m above the ground were calculated. The calculated dose rates and measured dose rates had a good correlation coefficient, R of 0.94. To evaluate the radiological hazard of the natural radioactivity, the radium equivalent activity, the gamma-absorbed dose rate and the mean population weighted dose rate were calculated. An isodose map for the Kinta District was also produced.
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http://dx.doi.org/10.1016/j.jenvrad.2009.01.001DOI Listing
May 2009

The thermoluminescence response of doped SiO2 optical fibres subjected to alpha-particle irradiation.

Appl Radiat Isot 2009 Mar 2;67(3):428-32. Epub 2008 Jul 2.

Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia.

Ion beams are used in radiotherapy to deliver a more precise dose to the target volume while minimizing dose to the surrounding healthy tissue. For optimum dose monitoring in ion-beam therapy, it is essential to be able to measure the delivered dose with a sensitivity, spatial resolution and dynamic range that is sufficient to meet the demands of the various therapy situations. Optical fibres have been demonstrated by this group to show promising thermoluminescence properties with respect to photon, electron and proton irradiation. In particular, and also given the flexibility and small size of optical fibre cores, for example 125.0+/-0.1 microm for the Al- and Ge-doped fibres used in this study, these fibres have the potential to fulfill the above requirements. This study investigates the thermoluminescence dosimetric characteristics of variously doped SiO(2) optical fibres irradiated with alpha particles from (241)Am. Following subtraction of the gamma contribution from the above source, the thermoluminescence characteristics of variously doped SiO(2) optical fibres have been compared with that of TLD-100 rods. The irradiations were performed in a bell jar. Of related potential significance is the effective atomic number, Z(eff) of the fibre, modifying measured dose from that deposited in tissues; in the present work, a scanning electron microscope and associated energy dispersive X-ray spectroscopy facility have been used to provide evaluation of Z(eff). For Ge-doped fibres, the effective atomic numbers value was 11.4, the equivalent value for Al-doped fibres was 12.3. This paper further presents results on dose response and the glow curves obtained. The results obtained indicate there to be good potential for use of variously doped SiO(2) optical fibres in measuring ion-beam doses in radiotherapeutic applications.
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http://dx.doi.org/10.1016/j.apradiso.2008.06.034DOI Listing
March 2009

Terrestrial gamma radiation dose study to determine the baseline for environmental radiological health practices in Melaka state, Malaysia.

J Radiol Prot 2005 Dec 5;25(4):435-50. Epub 2005 Dec 5.

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, 81310 Skudai, Johore Bahru, Johore, Malaysia.

Environmental terrestrial gamma radiation dose rates were measured throughout Melaka, Malaysia, over a period of two years, with the objective of establishing baseline data on the background radiation level. Results obtained are shown in tabular, graphic and cartographic form. The values of terrestrial gamma radiation dose rate vary significantly over different soil types and for different underlying geological characteristics present in the study area. The values ranged from 54 +/- 5 to 378 +/- 38 nGy h(-1). The highest terrestrial gamma dose rates were measured over soil types of granitic origin and in areas with underlying geological characteristics of an acid intrusive (undifferentiated) type. An isodose map of terrestrial gamma dose rate in Melaka was drawn by using the GIS application 'Arc View'. This was based on data collected using a NaI(Tl) scintillation detector survey meter. The measurements were taken at 542 locations. Three small 'hot spots' were found where the dose rates were more than 350 nGy h(-1). The mean dose rates in the main population areas in the mukims (parishes) of Bukit Katil, Sungai Udang, Batu Berendam, Bukit Baru and Bandar Melaka were 154 +/- 15, 161 +/- 16, 160 +/- 16, 175 +/- 18 and 176 +/- 18 nGy h(-1), respectively. The population-weighted mean dose rate throughout Melaka state is 172 +/- 17 nGy h(-1). This is lower than the geographical mean dose rate of 183 +/- 54 nGy h(-1). The lower value arises from the fact that most of the population lives in the central area of the state where the lithology is dominated by sedimentary rocks consisting of shale, mudstone, phyllite, slate, hornfels, sandstone and schist of Devonian origin which have lower associated dose rates. The mean annual effective dose to the population from outdoor terrestrial gamma radiation was estimated to be 0.21 mSv. This value is higher than the world average of 0.07 mSv.
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http://dx.doi.org/10.1088/0952-4746/25/4/006DOI Listing
December 2005

Statistical prediction of terrestrial gamma radiation dose rate based on geological features and soil types in Kota Tinggi district, Malaysia.

Appl Radiat Isot 2003 Nov-Dec;59(5-6):393-405

Department of Physics, Faculty of Science, Universiti Teknologi Malaysia Skudai, Johore 81310, Malaysia.

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.
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http://dx.doi.org/10.1016/j.apradiso.2003.08.003DOI Listing
February 2004