Archives-June... 

This paper proposes, with justification, a class of product-cum-dual to product estimators for estimating the population mean in systematic sampling using auxiliary information. The bias and variance of the proposed class of estimators have been derived under large sample approximation. Asymptotic optimum estimator (AOE) and its approximate variance estimator are derived and efficiency comparisons made with existing related estimators in theory. Analytical and numerical results show that at optimal conditions, the proposed class of estimators is always more efficient than all existing estimators under review.

This paper proposed a modified ratio-cum-product estimators of finite population mean using information on coefficient of variation and co-efficient of kurtosis of auxiliary variable in Stratified Ranked Set Sampling (SRSS). It has been shown that this method is highly beneficial to the estimation based on Stratified Simple Random Sampling (SSRS). The bias and mean squared error of the proposed estimators are derived. Theoretically, it is shown that these suggested estimators are more efficient than the estimators in Stratified simple random sampling. The results have been illustrated by numerical examples.

Now a days Public and private organizations increase their database system requirement for day-to-day business. Hence database security becomes more crucial as the scale of database is growing. A signified approach for protecting information which enforcing access control policies based on subject and object and their characteristics. There are many security models for database systems. The database security systems have developed a number of different access control policies for assuring data confidentiality, integrity and availability. In this paper we survey the concepts under access control policies for database security. We review the key access control policies such as Mandatory Access Control policy(MAC), Discretionary Access Control Policy(DAC), and Role Based Access Control Policy(RBAC) and propose a concept on RBAC policy that is instead of access control through role assigned to the users, the users are assigned by some level of access control.

Studies on levels of micronutrients and heavy metal concentration in soils provide vital information for best management options at all times. The study investigated levels of concentration of some heavy metals (Lead-Pb, Iron-Fe, Copper-Cu, Zinc-Zn and Manganese-Mn) on soils along Enugu-Abakaliki major express way in southeastern Nigeria in relation to the environmental and agronomic implication. Forty soil samples were collected at 0-40 cm depth from two environments (A and B). Results showed highly significant (P<0.01) mean lead (Pb) (16.37 mgkg-1) on the soils of Environment A than B (9.5 mgkg-1). Mean Pb in Ishieke I soil was significantly higher (P<0.05) than those of Boundary point II, Ezzamgbo II, and Ezzamgbo. Except Zn that was statistically similar, other metal mean values varied in concentration. Deficiency symptoms of macro- and micro-nutrients were observed on maize and tomato crops. Lime fertilizer was recommended. Continuous evaluation of soils for heavy metals should be an integral part of land use planning for long-term sustainability of farming systems and environmental stability.

Abstract Error analysis is among the interests of many language researchers. Beginning from the times when behaviorism was popular, and following the contrastive analysis studies, error analysis researches have been conducted and researchers aimed at having an insight into language development through their researches. Although language teaching approaches and methodologies have undergone some changes, error analysis still preserves its place in language teaching and likely to keep its significance in the future. This study investigated the erroneous usages of EFL writers through a controlled writing task. Participants of the study were 31 students at Düzce University, Social Work Department, Turkey. The study was conducted in the first semester of 2014-2015 academic year. Student errors that constituted the research data were grouped into 8 categories. The results of the study suggested that the majority of errors were in the conjugation of verbs with a 53.92 percent, where errors of omission, orthography, subject-verb agreement, substitution, word order, addition, and declension of nouns followed respectively. Resulting from the data obtained throughout the study, some instructional implications were provided mainly for the researchers, language teachers, curriculum designers, and coursebook authors. KEYWORDS: Error analysis, Controlled writing, Writing assessment, Error types

It is a well-known fact that solar resource or solar radiation varies spatially as well as temporally across the face of the earth. Hence, resource assessment is a preliminary step for all solar applications. In this study, a flat plate surface solar collector of dimension 2 m2, hinged on a horizontal support for quick adjustment of inclination from 0o to 80o was fabricated and marked out at 0.5o intervals on a telescopic leg graduated in degrees. Measurement of the solar radiation, varying degrees of inclination were taken between 11:00 a.m. and 4:00 p.m. for 7 days of each month at clear sky hours. The measurements were made for five months of the year in Tabriz, East-Azerbaijan Province, Iran. These months selected because they have maximum average solar radiation energy in Iran. At each 0.5 degree of inclination, the solar radiation intensity was replicated three times at each hour and the average value was taken. The flat plate was set truly facing south with an engineering prismatic compass. The result showed that the optimum tilt angle of a flat plate for maximum collection of solar radiation intensities in each month. This work also revealed that the average angle of inclination at which a flat plate surface solar collector will be mounted at fixed position in Tabriz is 31o approximately in studied months. The analysis indicated that when a flat surface was located at the forecasted optimum tilt angle for each of five months, solar radiation intensity was increased, when compared with solar radiation intensity harnessed by the same flat plate collector on other angles and under the same condition. Moreover this improvement impose no extra-cost. Comparison of the measured and calculated optimum values of tilt angle of a flat plate surface for trapping maximum solar radiation intensity for each of five months indicated a high correlation with R2 of 0.98 approximately.

Abstract: Dynamic assessment (henceforth, DA) is an approach to assessment which is derived from Vygotsky’s notion of zone of proximal development (ZPD). More precisely, DA is as an alternative to traditional testing which emphasizes greatly on the role of interaction. Recently, the focus of research has shifted from testing listening to teaching it through the use of dynamic assessment; therefore, the present paper aims at reviewing the implementation of dynamic assessment (DA) on listening comprehension. Reviewing the literature has shown that generally dynamic assessment has led learner’s development in listening comprehension. Moreover, the present paper concluded some valuable points. First, group dynamic assessment was conducted in most studies. Second, researchers applied mixed method in their researches. Third, interactionist kind of DA was mainly used and finally lower-intermediate and intermediate learners were the subjects of most studies

The heterogeneous catalytic activity of synthetic phosphate for conjugate addition was studied. This catalyst was prepared by calcination a mixture of fluorapatite and sodium nitrate. The conjugate addition between p-methoxychalcone and thiophenol has been used as model reaction. A central composite design was successfully employed for experimental design and analysis of the results. The combined effect of reaction time (X1), solvent volume (X2), catalyst weight (X3) and impregnation ratio (X4) on the reaction yield (Y) was studied and optimized using response surface methodology.

The FT?IR and FT?Raman spectra of benzyl fluoride were recorded and analyzed. The vibrational wavenumbers were examined theoretically with the aid of the GAUSSIAN 09 package of programs using the HF/6?311++G(d,p) and B3LYP/6?311++G(d,p) levels of theory. The data obtained from vibrational wavenumber calculations are used to assign vibrational bands obtained in IR and Raman spectroscopy of the studied molecule. The first hyperpolarizabililty, NBO, HOMO-LUMO, infrared intensities and Raman intensities are reported. The calculated first hyperpolarizability is comparable with the reported values of similar derivatives and is an attractive object for future studies of non?linear optics. The geometrical parameters of the title compound are in good agreement with the values of similar structures.

Understanding the molecular factor behind sex expression has immense importance both in basic and applied research. Determination of sex in Casuarina equisetifolia is of utmost important from the commercial forestry. Sex of plant is very important as number of female plants must be maximum. Plantation of seedlings of unknown sex leads to long term effects on yield. Hence correct identification of male and female genotypes at juvenile phase is important to maintain proper densities of female and male plants and dioecious nature also poses problem in tree breeding programmes. In many dioecious plants, gender influences economic value, breeding schemes, and/or opportunities for commercial use of genetically transformed materials.