 Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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- Caesarean Delivery- a Pressured Choice for Women: A Meta-Analysis of 23
Cross-Sectional Studies
Authors: Munira Nargis Ananna, Md Belal Hossain
Pages: 1 - 5
Abstract: The aim of this study is to investigate the associated factors which influence women to choose caesarean delivery or C-Section (CS) and to quantify the contribution of these factors. This meta-analysis indicates that for maternal age at birth, age group 20-29 years is 1.45 times more likely to choose CS as compared to the age group ≤19 years [OR= 1.45; Overall effect Z=4.57, p<0.01], for mother’s education level educated mothers are 8.86 times more likely to choose CS as compared to the uneducated mothers[OR= 8.86; Z=4.10, p<0.01].For marital status OR=1.40;Z= 1.34, p=0.18, for residence OR= 1.02;Z=0.11, p= 0.91, for mother’s employment status OR= 0.97;Z=-0.12, p= 0.90 and for receiving Antenatal Care between 1-3 times versus 0 time OR= 2.11;Z=1.84, p= 0.07. Mother’s economic status [OR= 1.41;Z=3.43, p<0.01], whether previous CS [OR=9.39; Z=2.24,p=0.03] and type of delivery facility [OR= 0.67; Z=-2.03, p= 0.04] are found to be significant factors for choosing CS over normal delivery. Dhaka Univ. J. Sci. 71(1): 1-5, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65265
Issue No: Vol. 71, No. 1 (2023)
- Crystal Field Splitting Energy (Δo) and Racah Parameters (B) of Some
Metal-Saccharine and Metal-Saccharine-Ethylenediamine Complexes
Authors: Saiful Islam, Humaiara Akter, Pradip Kumar Bakshi
Pages: 6 - 12
Abstract: [M(sac)2(H2O)4].2H2O [sac = saccharinato anion, M = Fe(II), Co(II), Ni(II), and Cu(II)], and [M(sac)2(en)2].2H2O [sac = saccharinato anion, en = ethylenediamine, M = Fe(II), Co(II), Ni(II) and Cu(II)] were prepared in an aqueous medium. The compounds are crystalline of different colors and are ambiently stable. By examining their physico-chemical properties and relevant literature, the metal(II) ions in both [M(sac)2(H2O)4].2H2O and [M(sac)2(en)2].2H2O complexes are octahedrally coordinated. In the former by four neutral H2O molecules and two monoanionic sac ligands while in later, the octahedral sites fulfilled by two neutral bidentate ethylenediamine molecules and two monoanionic sac ligands. Splitting of the crystal field (Δo) and Racah parameter (B) of two sets of complexes [M(sac)2(H2O)4].2H2O and [M(sac)2(en)2].2H2O are estimated from their electronic spectra using Tanabe-Sugano diagram of Co(II) and Ni(II) complexes while Δo values of Fe(II) and Cu(II) derivatives are calculated directly from their absorption maxima. Our experimental results show that for the studied ligands and the divalent transition metal ions, the Δo values vary according to the following order: Cu(II) > Fe(II) > Co(II) > Ni(II). Dhaka Univ. J. Sci. 71(1): 6-12, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65266
Issue No: Vol. 71, No. 1 (2023)
- Assessing Goodness of Approximate Distributions for Inferences about
Parameters in Nonlinear Regression Model
Authors: Md Jamil Hasan Karami
Pages: 13 - 16
Abstract: It is often crucial to make inferences about parameters of a nonlinear regression model due to a dependency of Fisher information on the parameter being estimated. Here, the distribution of the relevant test statistic is not exact, but approximate. Therefore, similar conclusion, based on the values of different test statistics, may not be reached. This study shows, in this circumstance, how to come up with a nonlinear regression model that can be used for forecasting and other related purposes. The goodness of the approximate distributions, F and χ 2 , has been assessed to reach a correct decision. The simulation results show that the simulated probability of committing a type I error is very close to its true value in case of F distribution corresponding to F statistic. However, the χ 2 distribution does not do a similar job for the LRT statistic since the simulated type I error is quite larger. Dhaka Univ. J. Sci. 71(1): 13-16, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65267
Issue No: Vol. 71, No. 1 (2023)
- A Simulation Based Comparative Study to Find Efficient Parameter
Estimation Methods for Weibull Distribution
Authors: Anamul Haque Sajib, Sabina Sharmin, Sharmin Akter
Pages: 17 - 25
Abstract: This paper aims to find efficient methods for estimating the parameters (shape =α , scale = β ) of Weibull distribution in different situations. The maximum likelihood estimation method (MLE), the median rank regression method (MRR), the least square method (LSM) and the weighted least square method (WLSM) are considered for the estimation of the parameters. The root mean square error (RMSE) criterion is used to measure the relative efficiency of the estimators experimentally (Monte Carlo simulation). From the simulation study, it is observed that the MLE produces the lowest RMSE, irrespective of all sample sizes, for decreasing hazard function(α << β ) (α is considerably smaller than β ) and roughly linear hazard function with a positive slope (α >1) . When (α >> β ) the WLSM produces the lowest RMSE for small sample sizes (n ≤ 40) but for large sample sizes it is the MLE, irrespective of all types of hazard functions. When (α ,β →1), the WLSM produces the lowest RMSE for small sample sizes (n ≤ 40) and the MLE for large sample sizes irrespective of all types of hazard functions. This pattern becomes reversed whenα and β have the larger value. Only the MLE gets stuck when the hazard function is parallel to Y − axis (α >> β ) and the WLSM is suitable in such a situation (lowest RMSE) irrespective of all sample sizes. Finally, the utility of simulation results have been illustrated by analyzing two real-life data sets. Dhaka Univ. J. Sci. 71(1): 17-25, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65268
Issue No: Vol. 71, No. 1 (2023)
- Analyzing Business Strategies of a Company in Bangladesh by Comparing
Three Rigorous Forecasting Techniques
Authors: M Babul Hasan, M Asadujjamanand, M Hasibul Haque
Pages: 26 - 35
Abstract: Business organizations in Bangladesh are basically running their business through intuition based forecasting. But it is crucial to anticipate the near future as accurate as possible to make the business profitable. This helps the manager of a business organization to plan their resources properly and as a result the organization can minimize its cost and maximize profit. In this research paper, we will analyze the business strategies of a company in Bangladesh by comparing the results obtained from three different rigorous forecasting techniques such as Holt’s method, Holt-Winter’s method and Autoregressive Integrated Moving Average (ARIMA) method so that the business organization can select proper forecasting technique to run their business. For this, we will first illustrate and analyze basics of forecasting and time series analysis, usual forecasting methods, some rigorous methods e.g., Holt’s method, Winter’s method and Autoregressive Integrated Moving Average (ARIMA) models. We will carry out our analysis and calculation by using Microsoft Excel, statistical data analysis tool R and MATHEMATICA. Dhaka Univ. J. Sci. 71(1): 26-35, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65269
Issue No: Vol. 71, No. 1 (2023)
- An Integrated Forecasting Technique with Modified Weight Measurement
Authors: M Babul Hasan, M Asadujjaman, M Hasibul Haque
Pages: 36 - 41
Abstract: Forecasting has long been part of our life since early of the history of human being. In the middle of 20th century forecasting becomes a part of every business and financial sectors. Nowadays every successful firm has to make its own forecasts with an acceptable error as there is no chance of zero error. The situation becomes more complicated if the observed data is more diverted from the existing pattern. In such situation it becomes more difficult to fit it into a suitable forecasting model.Then it requires to combine several forecasts to reach a better forecast.In this paper, we willdevelop a sophisticated forecasting technique bycombining the weighted average method with Linear Programming (LP) model by developing an alternative technique to calculate the weights. We will carry out our analysis by using Microsoft Excel, statistical data analysis tool R and MATHEMATICA. We will demonstrate our model by numerical examples. Dhaka Univ. J. Sci. 71(1): 36-41, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65270
Issue No: Vol. 71, No. 1 (2023)
- ZnO-Cu2O Composites for Photocatalytical Removal of Methylene Blue from
Aqueous Solution under Visible Light
Authors: Nasrin Akter, Mahbuba Zaman, Md Ataur Rahman, Md Mufazzal Hossain
Pages: 42 - 48
Abstract: ZnO-Cu2O composites were prepared by precipitation technique followed by calcination. The prepared composite was characterized by scanning electron microscopy (SEM), energy dispersion X-ray (EDX), Fourier transform infra-red (FT-IR) and X-ray diffraction (XRD). Band gap energy of the composite was determined by UV-visible reflectance measurement. The absorption range of the ZnO-Cu2O composite was shifted to the visible region due to the doping of Cu2O. SEM image represented that composite nanoparticle was smaller in size compared to the pure ZnO. The EDX spectral analysis showed that no elements other than Zn, Cu and O were present in the sample. XRD showed that ZnO-Cu2O composite was made of hexagonal ZnO and cubic Cu2O. The photocatalytic activity of ZnO-Cu2O composite was studied by degrading MB under different experimental conditions. The molar ratios of the composites, amount of the composite, initial concentration of dyes were varied to optimize the conditions for degradation. The experimental result was compared with those of commercial ZnO. It was found that the ZnO-Cu2O composite is a better photocatalyst than ZnO under visible light. Dhaka Univ. J. Sci. 71(1): 42-48, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65271
Issue No: Vol. 71, No. 1 (2023)
- Resistance to Sulphate and Acid Attack of Rice Husk Ash and Fly Ash Based
Composite Cement
Authors: Md Ershad Halim, Kazi Nasrin Farooque, Mohammed Mahmudul Hasan, Md Hasanur Rahman, Uzzal Shaha, Farhana Khanam Ferdousi, Umme Sarmeen Akhtar, Mohammad Ismail, Md Akramuzzaman
Pages: 49 - 55
Abstract: The current exploration work contains the preparation and examination of the properties of cement-based composite materials. Two kinds of composite materials specifically, Rice Husk Ash Composite Cement and Fly Ash Composite Cement were examined. Rice Husk Ash Composite Cement and Fly Ash Composite Cement was treated with Na2SO4 and HCl solution to check the resistance towards sulphate and acid attack respectively. Sulfate attack has been resolved in this work by estimating weight loss/gain of Ordinary Portland Cement (OPC) and the Composite Cements created from FA and RHA when plunged into 0.5 M and 0.75 M Na2SO4 solution. A loss in weight has been seen at the underlying stage i.e. Following 7 and 14 days when OPC is immersed in sulfate media, however, in the long run there was gain in weight of the composite made with OPC. The loss of weight occurred when the entire test sample is treated with 1.0 M HCl. Results on acid resistance and sulphate attack revealed that Composite cements are better acid resistant but more susceptible to sulphate attack. It was also observed that FAC composite is more susceptible to sulphate attack than RHAC composite. The Ca(OH)2 leaching tests indicate that Composite Cements are effective in reducing the amount of Ca(OH)2 leaching compared to pristine OPC. Dhaka Univ. J. Sci. 71(1): 49-55, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65272
Issue No: Vol. 71, No. 1 (2023)
- Optimization of 18F Radioisotope Production with Cyclone 18/9 MeV IBA
Cyclotron Installed at NINMAS
Authors: AFM Masum Rabbani, Md Shohag Mia, Hasan Mehdi, Sanchoy Chandra Biswasarma, Md Ariful Islam, Md Jashim Uddin, Tanvir Ahmed Biman, Mohammad Anwar Ul Azim, Md Nahid Hossain
Pages: 56 - 59
Abstract: A cyclotron is a particle accelerator, which employs electromagnetic fields to accelerate charged particles to extremely high speeds and energy. It is used to create radioisotopes for radiopharmaceuticals, which are used to diagnose and treat cancer. Because cyclotron-produced radiopharmaceuticals are exceptionally effective in identifying various cancers. Cyclotrons are fast evolving and will play an increasingly important role in the healthcare industry, particularly in advanced medical imaging techniques like positron emission tomography-computed tomography (PET-CT) and single photon emission computed tomography (SPECT). An 18/9 MeV cyclotron (18 MeV for proton and 9 MeV for deuteron, Model: Cyclone 18/9, IBA) was installed at the National Institute of Nuclear Medicine and Allied Science (NINMAS), Bangladesh Atomic Energy Commission (BAEC). Radioisotopes such as 18F, 11C, 13N, and 15O can be produced with this cyclotron. Solid target option is also available here which can be used for producing 67Ga, 68Ga, 124I, 123I, 111In, 99mTc, 64Cu, and 89Zr radioisotopes. 18F is the radioisotope of choice for many radiopharmaceuticals due to its glucose analogous and half-life of 110 min. We are producing FDG on a regular basis. For a 60-minute bombardment time, a 40 to 50 micro amp beam current is employed to produce 18F with a mass of 2500 to 3500 mCi. Because of the variable production parameters used, the production of 18F varies. Parameters used in the production of 18F radioisotope are limited to physical factors such as target material, target volume, collimator, stripper foil, and ion source. As a result, we consider 18F yield to be the most important aspect in providing sufficient activity since we want to find the best operating point that minimizes both production time and cost. In order to produce an optimal 18F radioisotope production, all parameters such as dee voltage, vacuum label, beam current, irradiation time, amount of enriched 18O water, target pressure, and others are taken into account. Dhaka Univ. J. Sci. 71(1): 56-59, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65273
Issue No: Vol. 71, No. 1 (2023)
- Application of Autoregressive Distributed Lag Model to Assess the
Environmental Sustainability in Bangladesh
Authors: Salma Akhter, Murshida Khanam
Pages: 60 - 68
Abstract: This research inspects the associations among several macroeconomic factors in Bangladesh using yearly time series data from 1971 to 2019. It also aimed to determine if the environmental Kuznets curve (EKC) hypothesis exists in Bangladesh or not. The findings from the stationarity tests reveal that all variables are ordered I (1) integrated. The ARDL model has been used to explore the longrun and short-run connections between variables in the model. In the long term, the projected findings established the existence of the Kuznets curve hypothesis in the GDP-energy nexus. According to the study, there is a U-shaped association between economic expansion and greenhouse gas emissions. Food production and energy consumption increase emissions, however using biomass does not assist the country to attain sustainability, as an increase in biomass increases greenhouse gas emissions by 1.12%. As a result, our government should explore additional renewable energy sources to restrict emissions and take the required actions in all areas to achieve environmental sustainability. Dhaka Univ. J. Sci. 71(1): 60-68, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65274
Issue No: Vol. 71, No. 1 (2023)
- Analyzing Overdispersed Skilled Antenatal Care Visits of Pregnant Women in
Bangladesh Using Generalized Poisson Regression Model
Authors: Md Muddasir Hossain Akib, Bikash Pal
Pages: 69 - 75
Abstract: It is common to use the Poisson regression model (PRM) for analyzing the count data. The major limitation of this PRM is that the mean and variance of the response variable need to be equal. However, in the actual dataset, the response variable’s variance may exceed the mean, introducing overdispersion in the dataset. In this paper, the generalized Poisson regression model (GPRM) has been used in the modeling and analysis of the skilled antenatal care (ANC) count data extracted from the Bangladesh Demographic and Health Survey (BDHS) 2017-18. The findings of this study have revealed several socioeconomic and demographic variables that significantly impact the skilled ANC visits. Dhaka Univ. J. Sci. 71(1): 69-75, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65275
Issue No: Vol. 71, No. 1 (2023)
- Evaluating the Accuracy of Chebyshev’s Inequality for Probability
Calculation: A Simulation Study
Authors: Tasmiah Afrin Emma, Anamul Haque Sajib, Sabina Sharmin
Pages: 76 - 81
Abstract: This paper aims to evaluate the accuracy of probability calculation using Chebyshev’s inequality based on simulation study. We consider symmetric (Normal (3,1.52 ), Laplace (3, 2 ) Beta (7.7 ) t5) positively skewed, negatively skewed (5 χ2, Beta (3, 8 ) Gamma (5,1)), (Beta (7, 2)), Exponential (5) and Uniform (0, 1 ) distributions, fx(x) in our simulation study to measure the performance of Chebyshev’s inequality. We then calculate Pr (μ − kσ ≤ X ≤ μ + kσ ) for ~ ( ) X X f x , μ = E ( X ) and σ 2 =Var ( X ), and compare this with the approximated probability obtained from Chebyshev’s inequality to measure the accuracy of Chebyshev’s inequality. From our simulation study, it is observed that loss due to using Chebyshev’s inequality for probability calculation is the least and the maximum when fx(x) is the Exponential and the Beta (symmetric) distributions, respectively for k ≥ 2.5. Moreover, the value of Pr (μ − kσ ≤ X ≤ μ + kσ ) calculated using Chebyshev’s inequality is underapproximated for all the probability distributions considered in the study. Dhaka Univ. J. Sci. 71(1): 76-81, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65276
Issue No: Vol. 71, No. 1 (2023)
- Characteristics of General Linear Group of Order 2 as Lie Group and Lie
Algebra
Authors: Md Shapan Miah, Khondokar M Ahmed, Salma Nasrin
Pages: 82 - 86
Abstract: The main target of this article is to study about Lie Groups, Lie Algebras. This article will enrich our knowledge about Algebraic properties of manifolds, how Lie Groups and Lie Algebras are working with their properties. Finally, we have discussed an example by showing all the properties of Lie Algebra,Lie Groups for a special Group and a Theorem has established. Dhaka Univ. J. Sci. 71(1): 82-86, 2023 (Jan)
PubDate: 2023-05-29
DOI: 10.3329/dujs.v71i1.65277
Issue No: Vol. 71, No. 1 (2023)
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