Photon Flux to Dose Rate Conversion Factors from Photon Exposure for Lung and Soft Tissues

The photon flux to dose conversion factor for the lung and the soft tissues from an idealized photon exposure at 1m AP was achieved using MCNPX®. The lung and the soft tissues of the modified Adult Male® phantom of ORNL were subjected to dose function modification, DE and DF. The estimated DF(E) for the energy range 0.1MeV to 15MeV compare favorably with the values of ANSI/ANS-6.1.1-1977

Determination of Appropriate Source-to-Detector Distance Dependence of Gamma Spectrometry System to Achieve Higher Resolution

Operation of gamma spectrometry requires intensive monitoring of gamma ray fluxes. When a radioactive intense source is placed close to a crystal detector, it becomes saturated as a result of detector dead time. On the contrary, when placed far away, there is loss of count statistics. For this reason, optimal position for placing the source has to be investigated. With the improvement in the instrumentation of radiation detection applications over the years, high count rate measurement accuracy is more crucial than ever. This is due to periodic measurement and new correction models for dead time. The aim of this study is to examine the performance of two gamma spectroscopic systems. The source detector distance dependence on dead time, peak-to-compton ratio, overall amplifier gain, FWHM, and voltage variation were investigated using American standard procedures (ANSI/IEE -325). Measurements were performed at five (5) different distances of detector cap for four (4) point sources (Co-60, Eu-152, Cs-137 and Ba-133). Source-to-detector distance at 25 cm was improved to avoid summing coincidence and dead time correction. The results obtained at 25 cm showed that the dead time was found less than 1% as compared to 4 cm. This will describe the stability of dead time. It also indicated that for both detectors the rise in biased voltage will yield a good resolution at 1332.5 KeV. This study is significant as it provides information to ensure that detectors are kept at optimal distance to achieve good dead time

The relationship between rural-urban migration, household income and unemployment: Malaysia case study

Internal migration is a key mechanism for the adjustment of regional economies, particularly when other devices proven fail.However, these processes have a highly factors of that specification complex economic, social, demographics, environmental, etc. Importance of internal migration, the 2009 World Development Report highlights that successfully economies are those that have the high density, mobility and integration.Migration is common element in most societies of population growth, so the scale of movements in developing countries is that the urban population may have the undesirable effects on poverty and development. Migration has come to consider rural-urban migration as a "major factor that contributed to these phenomenon in any urban and the excess of labor force directly exacerbate the unemployment problems in the city is serious" .Beyond the cross-border migration, internal migration, especially from rural to urban areas has been a key driver in the economic development of Malaysia.In 1970, more than 70% of the population lived in rural areas.By 2008, this number was reduced by half to around 35%. During the same period, the gap of urban and rural income has been reduced from a ratio of 1:2.1 to 1:1.8.Thus, the larger urbanization has contributed to the increasing average revenue and to improve quality of life. So, this paper provides a cursory of the literature examining to investigate the relationship between rural and urban migration, household income and unemployment in Malaysia by using data from 1980 to 2011.By using time series data, it has been found that migration is positively influenced by level of household income and negatively influenced by unemployment rate for rural and urban migration in Malaysia.Johansen co-integration, vector error correction model and granger causality test are employed to analyze the data

Analisis hubungan jangka panjang, jangka pendek beserta unjuran bagi migrasi dalaman dengan faktor penentu makroekonomi di Malaysia

Migrasi masuk merupakan satu fenomena penting yang boleh mendatangkan kesan baik atau buruk ke kawasan destinasi.Pelbagai faktor yang menjadi penyebab kepada migrasi yang berlaku ini seperti kemasukan pelaburan asing dan pelaburan domestik.Justeru itu, kajian ini ingin menganalisis hubungan faktor-faktor penentu dengan migrasi masuk dalam jangka panjang dan jangka pendek beserta unjuran dari tahun 2013 sehingga tahun 2020.Hasil kajian mendapati sekurang-kurangnya wujud satu hubungan jangka panjang di antara pemboleh ubah migrasi masuk dengan faktor penentu.Manakala bagi kaedah unjuran pula, pola migrasi masuk bagi lima negeri dijangkakan mengalami peningkatan, lapan negeri dijangkakan mengalami penurunan \manakala satu negeri dijangkakan tidak berubah

Comparison of Gravity Anomalies from Recent Global Geopotential Models with Terrestrial Gravity and Airborne Gravity over Johor Region

Gravity anomalies can yield an indirect but extremely useful picture of lateral changes in rock composition and structural patterns especially for rapid development area such as Johor region. The gravity anomalies can be derived from Global Geopotential Model (GGM) which is one of special product from the satellite technology that able to determine high accuracy of the earth's gravity field. In this study, the gravity anomalies derived from recent GGM published by International Global Geopotential Model were compared with five other GGMs model that compromised either terrestrial or airborne or both to derive the gravity anomalies.  In order to identify the best gravity model over the Johor region, two types of GGM class model has been selected for the comparisons which known as satellite only and combined class model.  The result shows that the gravity anomalies de-rived from satellite only class model with up 300 spherical harmonic coefficients is the best fit model and can be used as a reference for the Johor region. The RSME for the recent GGM via satellite only were +/- 5.865 and +/- 3.347 mGal for terrestrial and airborne gravity anomalies respectively compared to other GGM

Characterization of the urethane based tissue equivalent substitute for phantom construction: model molding, XCOM and MCNPX studies

The Soft and Lung tissue equivalent substitute (STES and LTES) were developed from urethane PMC121/30 Dry (A and B) of Smooth-On, USA. The part A and B were mixed in the ratio 1:1 and further mixed with calcium carbonate (CaCO3) at a ratio 2:1 by mass. Air moisture was extracted from the mixture for 10minutes. This is the STES and the density after air extraction was 1.04gcm-3. The LTES was developed by mixing the STES and polystyrene beads at a ratio 10:1 by mass. The density of the LTES was 0.25gcm-3 after air extraction. The STES and the LTES were subjected to compression test for stress-strain analysis. The elemental composition of STES and LTES was achieved using XCOM software with the IUPAC nomenclatures of the source compounds as inputs. The elemental composition obtained was used to modify the lung and the soft tissue material of the AMALE and AFEMALE computational phantom of ORNL. The phantom was subjected to photon exposure (0.06MeV-15.00MeV) using MCNPX Version 27e. The results from MCNPX provided the bremsstrahlung, positron annihilation, and the fluorescence energies that was used to estimate the g-factor. The mass-energy transfer coefficient (μtra/ρ) and the mass-energy absorption coefficient (μen/ρ) were calculated using the values of g-factor, the fluence and the Kerma. The μen/ρ of the tissue-equivalent agrees with the National Institute of Standard values and the ICRU 44. The STES and LTES are technically proper research and teaching models for dose measurements with these results

Engaging students in a critical style of reflective practice through formative assessment

Higher education teaching and learning employ different approaches and techniques to empower students' learning experiences. The critical style of reflective practice in higher education is significant in preparing students for professional development, research competencies and deep learning (Glass, 2015). The word reflection has diverse meanings, described as the continuous and active engagement towards any form of knowledge resources with the employment of critical thinking (Dewey, 1983). Schön (1983) emphasised reflection activity as a method of re-evaluating experiences in different forms comprising individual comprehension of self and others. The critical style of reflective practice requires continuous efforts, attempts, and complex thought processing of unstructured ideas from various resources (Moon, 1999). Reflection also includes experiences and the development of insights, which enable the active functioning of cognitive and affective elements (Boud et al.,1985). Therefore, the growth of reflective practice needs active engagement and thinking to arouse individual performance in reflection (Boud, Keogh & Walker, 1996)

Abandoned construction: Factors and ways to circumvent abandoned housing projects in Peninsular Malaysia

Abandoned housing projects are one the major problems in the housing industry in Peninsular Malaysia.A housing project is considered abandoned when construction activities on-site housing construction has ceased for 6 (six) months or more in a row, after the completion of the sale and purchase agreement has been signed by the developer and the buyer or the developer has put under the control of the Official Receiver and Controller of Housing.This paper reviewed information on the current issues of causes of occurrence of abandoned projects.The reasons leading to this problem are many.This catastrophe has caused multifarious problems to the stakeholders, particularly the purchasers who become the aggrieved parties.Until to date there is no effective and once-and-for-all means to face the problems of abandoned housing projects. This project aims to analyze the factors of existence abandoned housing project in Peninsular Malaysia and find the best way to revive this abandoned housing project

Detectability of fibrils by dilation technique in digital mammography

The detectability of fibrils in mammographic phantom images by morphological enhancement was analysed in the present study. Materials that mimic fibrils were imaged by a digital mammography machine at 28 and 29 kVP. The images were processed by a dilation technique to produce second set of images. Receiver operating characteristic analysis was performed to compare the detection performance from the two sets of images. As compared to original images, the 28 kVP's fibrils images from dilation technique become more prominence to be detected by observers. While at 29 kVP only a few observers can found the fibrils images from dilation technique. This study suggests morphological enhancement of mammography image did not increase the detection of low frequency signals of the images