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Continuous depletion in tin productions has led to a newly emerging industry that is a tin by-product (amang) processing industry to harness mega tons of tin by-products produced in the past. Amang composed of profitable multi-heavy minerals and rare-earth elements. With poorly established safety and health practices in operating plant, amang poses extremely high radioactivity problem associated with high occupational ionizing radiation exposures to workers and continuously impacting the local environment with radioactive contamination from industrial effluent and solid waste into lithosphere and water bodies. The radioactivity level of 238U and 232Th series in the mineral varies from few hundreds up to ~200,000 and ~400,000 Bq kg-1 respectively and are potential to yield more than ~ 30,000 nGy h-1 of gamma (γ) radiation exposure to plant workers. The study found out that for 8 h of work time, a worker is estimated to receive an average effective dose of 0.1 mSv per day from external γ radiation source with a maximum up to 2 mSv per day for extreme exposure situation. Interferences of different exposure routes for examples inhalation of equivalent equilibrium concentration (ECC) of 222Rn and 220Rn progenies and airborne long-lived α particles from the dusty working environment could pose a higher total effective dose as much as 5 mSv per day and 115 mSv per year. The value is 5 times higher than the annual dose limit for designated radiation worker (20 mSv) in Peninsular Malaysia. The study found that 41% of the total received an effective dose received by a worker is contributed by 222Rn, 32% of airborne particulates and dust, 23% from external γ exposure and 4% from 220Rn. Based on radioecological risk assessment, the study found out that the aquatic environment is the highly exposed group to ionizing radiation from industrial effluent discharge and sand residues. With the impotent establishment of radiation protection in the industry, plus the country newly introduced long-term plan to revive tin mining as well as its accessory amang mineral, it is necessary for the government to harmonize current regulation to improve the worker safety and health as well as sustaining local environment.
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Poluentes Radioativos do Ar/análise , Exposição Ocupacional , Doses de Radiação , Monitoramento de Radiação , Poeira , Meio Ambiente , Raios gama , Humanos , Malásia , Minerais , MineraçãoRESUMO
It has been highlighted that the original manuscript [1] contains a typesetting error regarding the authorship.
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BACKGROUND: Recent studies have shown that breast cancer subtype can change from the primary tumour to the recurrence. Discordance between primary and recurrent breast cancer has implications for further treatment and ultimately prognosis. The aim of the study was to determine the rate of change between primary and recurrence of breast cancer and to assess the impact of these changes on survival and potential treatment options. METHODS: Patient demographics were collected on those who underwent surgery for breast cancer between 2001 and 2014 and had a recurrence with biopsy results and pathology scoring of both the primary and recurrence. RESULTS: One hundred thirty two consecutive patients were included. There were 31 (23.5%) changes in subtype. Discordance occurred most frequently in luminal A breast cancer (n = 20), followed by triple negative (n = 4), luminal B (n = 3) and HER2 (n = 3). Patients who changed from luminal A to triple negative (n = 18) had a significantly worse post-recurrence survival (p < 0.05) with overall survival approaching significance (p = 0.064) compared to concordant luminal A cases (n = 46). Overall receptor discordance rates were: estrogen receptor 20.4% (n = 27), progesterone receptor 37.7% (n = 50) and HER2 3% (n = 4). Loss of estrogen receptor and progesterone receptor was more common than gain (21 vs. 6 (p = 0.04) and 44 vs. 6 (p = 0.01) respectively). Nine patients (6.8%) gained receptor status potentially impacting treatment options. CONCLUSION: Discordance in subtype and receptor status occurs between primary and recurrent breast cancer, ultimately affecting survival and potentially impacting treatment options.
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BACKGROUND: The Diabetes Mellitus in the Offspring Questionnaire (DMOQ) assesses the perceptions of Type 2 diabetes mellitus (T2DM) patients on the risk of their offspring developing T2DM and the possibility of intervention to reduce this risk. It has 34 items framed within seven domains. This study aimed to adapt, translate and validate the DMOQ from English into the Malay language. METHODS: This was a cross-sectional validation study among 159 T2DM patients attending a public primary care clinic in Selangor. The DMOQ English version underwent adaptation, translation, face validation and field testing to produce the Malay version. Psychometric analysis was performed using Exploratory Factor Analysis, internal consistency and testretest reliability. RESULTS: The DMOQ domains were conceptually equivalent between English and Malay language. A total of 13 items and two domains were removed during the validation process (three items during the content validation, three items due to poor factor loadings, five items as they loaded onto two domains which were not interpretable, one item as it did not fit conceptually into the factor it loaded onto and one openended question as it did not fit into the retained domains). Therefore, the final DMOQ Malay version consisted of 21- items within five domains. The Cronbach alpha was 0.714 and the intraclass-correlation coefficient was 0.868. CONCLUSION: The DMOQ Malay version is a valid and reliable tool which is consistent over time. It can be used to examine the perception of T2DM patients towards the risk of their offspring developing diabetes and possibility of intervention in Malay-speaking patients.
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Diabetes Mellitus Tipo 2/psicologia , Pais/psicologia , Filho de Pais com Deficiência/estatística & dados numéricos , Estudos Transversais , Diabetes Mellitus Tipo 2/epidemiologia , Análise Fatorial , Feminino , Humanos , Malásia , Masculino , Pessoa de Meia-Idade , Psicometria , Reprodutibilidade dos Testes , Fatores de Risco , Inquéritos e Questionários , TraduçãoRESUMO
INTRODUCTION: Non-communicable diseases (NCD) is a global health threat. the Chronic Care Model (CCM) was proven effective in improving NCD management and outcomes in developed countries. Evidence from developing countries including Malaysia is limited and feasibility of CCM implementation has not been assessed. this study intends to assess the feasibility of public primary health care clinics (PHC) in providing care according to the CCM. METHODOLOGY: A cross-sectional survey was conducted to assess the public PHC ability to implement the components of CCM. All public PHC with Family Medicine Specialist in Selangor and Kuala Lumpur were invited to participate. A site feasibility questionnaire was distributed to collect site investigator and clinic information as well as delivery of care for diabetes and hypertension. RESULTS: there were a total of 34 public PHC invited to participate with a response rate of 100%. there were 20 urban and 14 suburban clinics. the average number of patients seen per day ranged between 250-1000 patients. the clinic has a good mix of multidisciplinary team members. All clinics had a diabetic registry and 73.5% had a hypertensive registry. 23.5% had a dedicated diabetes and 26.5% had a dedicated hypertension clinic with most clinic implementing integrated care of acute and NCD cases. DISCUSSION: the implementation of the essential components of CCM is feasible in public PHCs, despite various constraints. Although variations in delivery of care exists, majority of the clinics have adequate staff that were willing to be trained and are committed to improving patient care.
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Doença Crônica/terapia , Atenção Primária à Saúde/organização & administração , Estudos Transversais , Diabetes Mellitus/terapia , Estudos de Viabilidade , Humanos , Hipertensão/terapia , Malásia , Modelos Organizacionais , Atenção Primária à Saúde/métodos , Inquéritos e QuestionáriosRESUMO
Malaysia has initiated a range of pre-project activities in preparation for its planned nuclear power programme. Clearly one of the first steps is the selection of sites that are deemed suitable for the construction and operation of a nuclear power plant. Here we outline the Malaysian regulatory requirements for nuclear power plant site selection, emphasizing details of the selection procedures and site characteristics needed, with a clear focus on radiation safety and radiation protection in respect of the site surroundings. The Malaysia Atomic Energy Licensing Board (AELB) site selection guidelines are in accord with those provided in International Atomic Energy Agency (IAEA) and United Stated Nuclear Regulatory Commission (USNRC) documents. To enhance the suitability criteria during selection, as well as to assist in the final decision making process, possible assessments using the site selection characteristics and information are proposed.
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Arquitetura de Instituições de Saúde/normas , Regulamentação Governamental , Centrais Nucleares/normas , Humanos , MalásiaRESUMO
An extensive terrestrial gamma radiation dose (TGRD) rate survey has been conducted in Perak State, Peninsular Malaysia. The survey has been carried out taking into account geological and soil information, involving 2930 in situ surveys. Based on geological and soil information collected during TGRD rate measurements, TGRD rates have been predicted in Perak State using a statistical regression analysis which would be helpful to focus surveys in areas that are difficult to access. An equation was formulated according to a linear relationship between TGRD rates, geological contexts and soil types. The comparison of in situ measurements and predicted TGRD dose rates was tabulated and showed good agreement with the linear regression equation. The TGRD rates in the study area ranged from 38 nGy h(-1) to 1039 nGy h(-1) with a mean value of 224 ± 138 nGy h(-1). This value is higher than the world average as reported in UNSCEAR 2000. The TGRD rates contribute an average dose rate of 1.37 mSv per year. An isodose map for the study area was developed using a Kriging method based on predicted and in situ TGRD rate values.
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Raios gama , Poluentes Radioativos do Solo/análise , Fenômenos Geológicos , Malásia , Doses de Radiação , Monitoramento de RadiaçãoRESUMO
Dengue is life-threatening and the paediatric population is highly susceptible to complications. Deterioration can occur rapidly and ability to recognise early warning signs is crucial. This study aims to determine the knowledge and awareness of parents and carers and to predict their ability in recognising life-threatening symptoms and signs of dengue in children and to assess their health-seeking behaviour in dengue emergency. Methods This is a crosssectional study involving parents and carers of children ≤ 12 years old in schools and kindergartens in the Gombak district. Demographic details, knowledge on life-threatening symptoms and signs of dengue and health-seeking behaviour were collected using a self-administered questionnaire and knowledge scoring was done. The questionnaire was pilot tested with a Cronbach alpha of 0.82. The results were analysed using SPSS version 20.0. Results Total respondents were 866 with 44.8% men and 55.2% women. The mean age was 40.3 years (SD ± 5.7). Knowledge score of dengue life threatening features among respondents were good (30.0%) to average (56.8%). Respondents were able to recognise fever (98.5%), petechial rash (97.1%) and bleeding (65.2%) but were less able to recognise abdominal pain (22.3%) and passing less urine (28.2%) as life threatening dengue features. However, the ability to recognise fever is a poor predictor in recognising life threatening dengue in children compared to all other symptoms which were good predictors. A respondent that recognise stomach pain or neck stiffness were five times more likely to recognise life-threatening dengue. Respondents preferred to bring their children to the clinic (50.8%) or hospital (37.8%) themselves Instead of calling for ambulance. Worryingly, some would give antipyretics (3.6%) or wait for improvements (7.8%). Conclusion Concerted efforts by the schools, healthcare professionals and health authorities are required to educate parents and carers to identify life-threatening features of dengue and to improve their health seeking-behaviour.
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BACKGROUND: Spatial separation in emergency departments (EDs) is empirically practised as part of transmission-based precaution. Despite its potential benefits in segregating potentially infectious patients, the effects of spatial separation on patient flow remain uncertain. AIM: To explore the impact of spatial separation on ED patient flow and to identify specific clinical factors and flow process intervals (FPIs) influencing ED length of stay (EDLOS). METHODS: This was a retrospective study of data extracted from patients' electronic medical records from January 1st to March 31st, 2022 conducted at the ED of a tertiary hospital in Kuala Lumpur, Malaysia. During this period, patients were separated into respiratory areas (RA) and non-respiratory areas (NRA) based on Centers for Disease Control and Prevention recommendations. The study obtained ethics approval from the institution's ethics board. FINDINGS: A total of 1054 patients were included in the study, 275 allocated to RA and 779 to NRA. Patients in RA had a significantly longer median EDLOS compared with NRA (9 h 29 min vs 7 h 6 min, P < 0.001, d = 0.41). A lower proportion of patients in RA achieved an EDLOS ≤8 h compared to NRA (41.8% vs 58.3%, P < 0.001). Independent factors affecting EDLOS were: triage category; re-triaging; hypertension; performing biomedical imaging; medical, surgical, and critical care consultations; and disposition plan. Bottlenecks significantly prolonging EDLOS were decision-to-departure, ultrasound interval, and referral-to-consultation. CONCLUSION: Spatial separation prolongs FPIs and EDLOS. Addressing inpatient access block and streamlining specialty review and biomedical imaging processes may reduce RA EDLOS.
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Serviço Hospitalar de Emergência , Tempo de Internação , Humanos , Serviço Hospitalar de Emergência/estatística & dados numéricos , Estudos Retrospectivos , Feminino , Masculino , Pessoa de Meia-Idade , Malásia , Tempo de Internação/estatística & dados numéricos , Adulto , Idoso , Centros de Atenção Terciária/estatística & dados numéricos , Adulto Jovem , Adolescente , Idoso de 80 Anos ou maisRESUMO
Presentation of baseline data on terrestrial gamma radiation (TGR) levels is crucial for assessing the annual effective dose received by the public due to natural radiation exposure. Cumulative doses from various sources can become significant, warranting a spatial understanding of TGR distribution. Few countries have comprehensively mapped TGR on a national scale, often facing challenges due to remote or inaccessible regions. This study investigated the influence of weathered soil groups on TGR dose rates in Sarawak-Borneo, Malaysia, to facilitate insights for TGR projection and isodose mapping. A total of 1044 TGR dose rate measurements were collected using NaI (Tl) scintillation detector survey meters, with a mean of 100 nGy h-1 and a range of 8-375 nGy h-1. Non-parametric statistical analyses of variance using Welch's ANOVA, Brown-Forsythe, and Kruskal-Wallis validated (P-sig.=.000) notable dissimilarities among six categories of superficial-weathered soil. Graphical analysis using Sinclair's cumulative plot revealed deviations at intervals of 50, 80, 100, 120, 175, and 205 nGy h-1. These deviations indicate distinct lithological influences. Skeletal soil (entisols) and podzolic soils had high mean dose rates (148 and 113 nGy h-1, respectively) due to limited development, thus preserving abundant uranium (U) and thorium (Th). Meanwhile, gleysols and thionic soils exhibited compatible means (90 and 82 nGy h-1, respectively), while alluvial (or transported soils) and organic soils displayed lower dose rate ranges (mean of 76 and 47 nGy h-1, respectively), reflecting rapid hydrolysis weathering processes. Simple linear regression analysis revealed a strong relationship between TGR dose rate and mean value of weathered soil groups (y = 0.851x + 0.141 nGy h-1), signifying the significance and magnitude of weathered soil groups' impact on TGR dose rates. The obtained R-value is 0.704, indicating a strong linear correlation among soil group variables, and a Durbin-Watson statistic of 1.41, suggesting positive autocorrelation among residuals, thus positive relationships. An isodose map was successfully developed using the Kriging technique, aligning with lithological features of the study area. Semivariogram analysis reveals spatial dependence within a range of 1.47°, supporting the Kriging technique's suitability for spatial inference. In conclusion, this study has successfully revealed the relationship between TGR dose rates and superficial-weathered soil in Sarawak-Borneo. While the linear relationship is applicable to the Sundaland-Borneo tectonic block, it has potential to be used as a valuable tool for spatial inference of TGR dose rates in isodose development with similar lithologial characteristics, aiding in radiation exposure assessment and environmental monitoring.
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Terrestrial radioactivity monitoring of 238U and 232Th series, and 40K in soil is an essential practice for radioactivity and radiation measurement of a place. In conventional practice, only basic data can be in-situ measured using a survey instrument, for example radioactivity concentration in soil and ambient dose equivalent rate. For other physical quantities, for example organ absorbed dose and organ equivalent dose, the measurement is impossible to be performed and can only be computed using Monte Carlo radiation transport simulations. In the past, most of the works only focused on calculating air-kerma-to-effective dose conversion factors. However, the information on organ dose conversion factors is scarcely documented and reported. This study was conducted to calculate organ absorbed and tissue-weighted equivalent dose conversion factors as a result of exposure from terrestrial gamma radiation. Series of organ dose conversion factors is produced based on computations from Monte Carlo MCNP5 simulations using modelled gamma irradiation geometry and established adult MIRD phantom. The study found out that most of the radiation exposed organs absorb energy at comparable rates, except for dense and superficial tissues i.e., skeleton and skin, which indicated slightly higher values. The good agreement between this work and previous studies demonstrated that our gamma irradiation geometry and modelling of gamma radiation sources are adequate. Therefore, the proposed organ dose conversion factors from this study are reasonably acceptable for dose estimation in environmental radioactivity monitoring practices.
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Especificidade de Órgãos , Monitoramento de Radiação/métodos , Poluentes Radioativos do Solo/farmacocinética , Raios gama , Humanos , Método de Monte Carlo , Imagens de Fantasmas , FótonsRESUMO
INTRODUCTION: The Patient Activation Measure (PAM) is one of the most extensively used, widely translated, and tested instruments worldwide in measuring patient activation levels in self-management. This study aimed to determine the validity and reliability of the PAM-13 Malay version among patients with Metabolic Syndrome (MetS) attending a primary care clinic. METHODS: This work is a cross-sectional validation study among patients with MetS attending a university primary care clinic in Selangor. The PAM-13 Malay version underwent a validation process and field testing. Psychometric properties were examined using principal component analysis (PCA) with varimax rotation, scree plot, Monte Carlo simulation, internal consistency, and test-retest reliability analyses. RESULTS: The content of the PAM-13 Malay version and the original version were conceptually equivalent. The questionnaire was refined after face validation by 10 patients with MetS. The refined version was then field-tested among 130 participants (response rate 89.7%). The Kaiser-Meyer-Olkin test was 0.767, and Bartlett's test of sphericity was ≤0.001, indicating sampling adequacy. Two factors were identified and labeled as (1) Passive and Building Knowledge, and (2) Taking Action and Maintaining Behavior. These labels were chosen as they were conceptually consistent with the items representing the levels of activation in PAM-13. The validated PAM-13 Malay version consisted of 13 items, framed into two domains. The overall Cronbach's α was 0.79, and the intraclass correlation coefficient was 0.45. CONCLUSIONS: The PAM-13 Malay version is valid, reliable, and fairly stable over time. This questionnaire can be used to evaluate the levels of activation among patients with MetS in primary care in Malaysia.
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It remains a challenge to diagnose aortic dissection in primary care, as classic clinical features are not always present. This case describes an atypical presentation of aortic dissection, in which the patient walked in with pleuritic central chest pain associated with a fever and elevated C-reactive protein. Classic features of tearing pain, pulse differentials, and a widened mediastinum on chest X-ray were absent. This unusual presentation highlights the need for a heightened level of clinical suspicion for aortic dissection in the absence of classic features. The case is discussed with reference to the literature on the sensitivity and specificity of the classic signs and symptoms of aortic dissection. A combination of the aortic dissection detection risk score (ADD-RS) and D-dimer test is helpful in ruling out this frequently lethal condition.
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Kuala Lumpur has been undergoing rapid urbanisation process, mainly in infrastructure development. The opening of new township and residential in former tin mining areas, particularly in the heavy mineral- or tin-bearing alluvial soil in Kuala Lumpur, is a contentious subject in land-use regulation. Construction practices, i.e. reclamation and dredging in these areas are potential to enhance the radioactivity levels of soil and subsequently, increase the existing background gamma radiation levels. This situation is worsened with the utilisation of tin tailings as construction materials apart from unavoidable soil pollutions due to naturally occurring radioactive materials in construction materials, e.g. granitic aggregate, cement and red clay brick. This study was conducted to assess the urbanisation impacts on background gamma radiation in Kuala Lumpur. The study found that the mean value of measured dose rate was 251±6nGyh-1 (156-392nGyh-1) and 4 times higher than the world average value. High radioactivity levels of 238U (95±12Bqkg-1), 232Th (191±23Bqkg-1,) and 40K (727±130Bqkg-1) in soil were identified as the major source of high radiation exposure. Based on statistical ANOVA, t-test, and analyses of cumulative probability distribution, this study has statistically verified the dose enhancements in the background radiation. The effective dose was estimated to be 0.31±0.01mSvy-1 per man. The recommended ICRP reference level (1-20mSvy-1) is applicable to the involved existing exposure situation in this study. The estimated effective dose in this study is lower than the ICRP reference level and too low to cause deterministic radiation effects. Nevertheless based on estimations of lifetime radiation exposure risks, this study found that there was small probability for individual in Kuala Lumpur being diagnosed with cancer and dying of cancer.
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Radiação de Fundo , Exposição à Radiação/análise , Urbanização , Adulto , Materiais de Construção , Humanos , Malásia , Mineração , Doses de Radiação , Monitoramento de Radiação , Medição de Risco , Poluentes Radioativos do SoloRESUMO
OBJECTIVES: To assess whether or not opportunistic oral cancer screening by dentists to detect pre-malignant or early cancer lesions is feasible. The objective was to analyse the patterns of dental attendance of a national representative sample over a period of 10 years to ascertain whether individuals at high-risk of oral cancer would be accessible for opportunistic oral cancer screening. METHODS: Secondary analysis of data extracted from the British Household Panel Survey, a national longitudinal survey (n=5547). Analysis to ascertain whether patterns of attendance for dental check-ups for a period of 10 years (1991-2001) were associated with risk factors for oral cancer such as age, sex, education, social class, smoking status and smoking intensity. RESULTS: Males, aged over 40 years, less educated manual workers and smokers were significantly less likely to attend for dental check-ups compared with females and younger, higher educated, higher socio-economic class non-smokers (p < 0.05). Throughout the 10-year period, young people, more than older people, had progressively lower odds ratios of attending. Those with more education used dental services more. Heavy smokers were infrequent attendees. CONCLUSIONS: This study suggests that opportunistic oral cancer screening by dentists is not feasible to include high-risk groups as they are not regular attendees over 10 years. Those who would be screened would be the low-risk groups. However, dentists should continue screening all patients as oral precancers are also found in regular attendees. More should be done to encourage the high-risk groups to visit their dentists.
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Assistência Odontológica/estatística & dados numéricos , Programas de Rastreamento/métodos , Neoplasias Bucais/diagnóstico , Visita a Consultório Médico/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Métodos Epidemiológicos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Distribuição por Sexo , Fumar/efeitos adversos , Fatores SocioeconômicosRESUMO
The quality of rice in terms not only of its nutritional value but also in terms of its aroma and flavour is becoming increasingly important in modern rice breeding where global targets are focused on both yield stability and grain quality. In the present paper we have exploited advanced, multi-platform metabolomics approaches to determine the biochemical differences in 31 rice varieties from a diverse range of genetic backgrounds and origin. All were grown under the specific local conditions for which they have been bred and all aspects of varietal identification and sample purity have been guaranteed by local experts from each country. Metabolomics analyses using 6 platforms have revealed the extent of biochemical differences (and similarities) between the chosen rice genotypes. Comparison of fragrant rice varieties showed a difference in the metabolic profiles of jasmine and basmati varieties. However with no consistent separation of the germplasm class. Storage of grains had a significant effect on the metabolome of both basmati and jasmine rice varieties but changes were different for the two rice types. This shows how metabolic changes may help prove a causal relationship with developing good quality in basmati rice or incurring quality loss in jasmine rice in aged grains. Such metabolomics approaches are leading to hypotheses on the potential links between grain quality attributes, biochemical composition and genotype in the context of breeding for improvement. With this knowledge we shall establish a stronger, evidence-based foundation upon which to build targeted strategies to support breeders in their quest for improved rice varieties.
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Concentrations of uranium-238 and thorium-232 in soil, water, grass, moss and oil-palm fruit samples collected from an area of high background radiation were determined using neutron activation analysis (NAA). U-238 concentration in soil ranged from 4.9 mg kg(-1) (58.8 Bq kg(-1)) to 40.4 mg kg(-1) (484.8 Bq kg(-1)), Th-232 concentration ranged from 14.9 mg kg(-1) (59.6 Bq kg(-1)) to 301.0 mg kg(-1) (1204 Bq kg(-1)). The concentration of U-238 in grass samples ranged from below the detection limit to 0.076 mg kg(-1) (912 mBq kg(-1)), and Th-232 ranged from 0.008 mg kg(-1) (32 mBq kg(-1)) to 0.343 mg kg(-1) (1.372 Bq kg(-1)). U-238 content in water samples ranged from 0.33 mg kg(-1) (4.0 Bq L(-1)) to 1.40 mg kg(-1) (16.8 Bq L(-1)), and Th-232 ranged from 0.19 mg kg(-1) (0.76 Bq L(-1)) to 0.66 mg kg(-1) (2.64 Bq L(-1)). It can be said that the concentrations of environmental U-238 and Th-232 in grass and water samples in the study area are insignificant. Mosses were found to be possible bio-radiological indicators due to their high absorption of the heavy radioelements from the environment.
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Tório/análise , Urânio/análise , Briófitas/química , Monitoramento Ambiental , Frutas/química , Malásia , Poaceae/química , Valores de Referência , SoloRESUMO
Measurements of environmental terrestrial gamma radiation dose-rate (TGRD) have been made in Johore, Malaysia. The focus is on determining a relationship between geological type and TGRD levels. Data were compared using the one way analysis of variance (ANOVA), in some instances revealing significant differences between TGRD measurements and the underlying geological structure.
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Raios gama/efeitos adversos , Geologia , Exposição Ambiental , Fenômenos Geológicos , Humanos , Malásia , Doses de Radiação , Poluentes Radioativos do Solo/efeitos adversos , Poluentes Radioativos do Solo/análiseRESUMO
Wavelet-based image coding algorithms (lossy and lossless) use a fixed perfect reconstruction filter-bank built into the algorithm for coding and decoding of images. However, no systematic study has been performed to evaluate the coding performance of wavelet filters on medical images. We evaluated the best types of filters suitable for medical images in providing low bit rate and low computational complexity. In this study a variety of wavelet filters are used to compress and decompress computed tomography (CT) brain and abdomen images. We applied two-dimensional wavelet decomposition, quantization and reconstruction using several families of filter banks to a set of CT images. Discreet Wavelet Transform (DWT), which provides efficient framework of multi-resolution frequency was used. Compression was accomplished by applying threshold values to the wavelet coefficients. The statistical indices such as mean square error (MSE), maximum absolute error (MAE) and peak signal-to-noise ratio (PSNR) were used to quantify the effect of wavelet compression of selected images. The code was written using the wavelet and image processing toolbox of the MATLAB (version 6.1). This results show that no specific wavelet filter performs uniformly better than others except for the case of Daubechies and bi-orthogonal filters which are the best among all. MAE values achieved by these filters were 5 x 10(-14) to 12 x 10(-14) for both CT brain and abdomen images at different decomposition levels. This indicated that using these filters a very small error (approximately 7 x 10(-14)) can be achieved between original and the filtered image. The PSNR values obtained were higher for the brain than the abdomen images. For both the lossy and lossless compression, the 'most appropriate' wavelet filter should be chosen adaptively depending on the statistical properties of the image being coded to achieve higher compression ratio.