Delineation of Weathered Layer Using Uphole and Surface Seismic Refraction Methods in Parts of Niger Delta, Nigeria

Uphole and surface seismic refraction surveys were carried out in parts of the Niger Delta, Nigeria, to delineate weathering thickness and velocity associated with aweathered layer. A total of twelve uphole and surface seismic refraction surveyswere shot, computed and analyzed. The velocity of the uphole seismic refraction ranged from 344.8 to 680.3 m/s with a thickness of 5.45 to 13.35 m. Surface seismic refraction ranged from 326.6 to 670.2 m/s and 4.30 to 12.0 m, respectively. The average velocity and thickness ranged from 559.6 to 548.0 m/s and 9.43 to 8.63m with differences of 11.6 m/s and 0.83 m respectively. The VW/VS ratios ranged from 0.955 to 1.059. This indicates that the uphole velocity is higher than the surface refraction velocity leading to low VW/VS values. This is a direct experimental proof of a low velocity zone, confirming the weathered nature of the area. The results of both refraction methods are reliable; the differences in surface refraction values are due to shot point offsets. Based on these findings, it is recommended that shots for seismic surveys should be located above 15.0 m in the area to delineate the effects associated with weathered layers to ensure that will be competent to withstand engineering structures.

Boolean Zero Square (BZS) Semigroups

We introduce a new class of semigroups, that we call BZS - Boolean Zero Square-semigroups. A semigroup S with a zero element, 0, is said to be a BZS semigroup if, for every , we have or . We obtain some properties that describe the behaviour of the Green’s equivalence relations , , and . Necessary and sufficient conditions for a BZS semigroup to be a band and an inverse semigroup are obtained. A characterisation of a special type of BZS completely 0-simple semigroup is presented.

Predator-Prey Model with Refuge, Fear and Z-Control

In this paper, we consider a predator-prey model incorporating fear and refuge. Our results show that the predator-free equilibrium is globally asymptotically stable if the ratio between the death rate of predators and the conversion rate of prey into predator is greater than the value of prey in refuge at equilibrium. We also show that the co-existence equilibrium points are locally asymptotically stable if the value of the prey outside refuge is greater than half of the carrying capacity. Numerical simulations show that when the intensity of fear increases, the fraction of the prey inside refuge increases; however, it has no effect on the fraction of the prey outside refuge, in the long run. It is shown that the intensity of fear harms predator population size. Numerical simulations show that the application of Z-control will force the system to reach any desired state within a limited time, whether the desired state is a constant state or a periodic state. Our results show that when the refuge size is taken to be a non-constant function of the prey outside refuge, the systems change their dynamics. Namely, when it is a linear function or an exponential function, the system always reaches the predator-free equilibrium. However, when it is taken as a logistic equation, the system reaches the co-existence equilibrium after long term oscillations.

Comparing Science and Engineering Students Using the Force Concept Inventory in Introductory Physics Courses

This work is intended to analyze and compare the performance of two groups of students on the understanding of force and motion concepts using the Force Concept Inventory (FCI). The FCI test serves questions on basic Newtonian concepts where the answers inclyde the correct response and commonly misconceived alternatives. The FCI test was implemented twice as pre and post-tests for two introductory calculus-based physics courses offered at the Sultan Qaboos University (SQU) in Oman for students mainly from the Colleges of Sciences, Education and Agriculture and the students from the College of Enginerring in the Spring 2017 and Spring 2018 semesters. These courses cover the traditional first-year level kinematics and dynamics in translational and rotational motions based on the same syllabus and the same textbook. Hake's normalized gain, defined as the change in class averages divided by the maximum possible increase, was used to compare the students'performances. The normalized gains for both groups of students were in the low gain category. Female students in both courses performed better on the FCI in general, but the difference was only statistically significant in the course offered to Science students.

A Surface Network Based on Polytyramine/ Gold Nanoparticles: Characterization, Kinetics, Thermodynamics and Selective Determination of Norepinephrine

A solid-state sensor was fabricated by a spontaneous electrochemical deposition of polytyramine (Ptyr) film onto a glassy carbon electrode (GCE) which was further peripherally supported by gold nanoparticles (AuNPs). The surface materials of the developed sensor (AuNPs.Ptyr-GCE) were characterized by X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The rate constant of charge transfers (kct) of the as-prepared sensor (8.77 × 10-4 cm/s) was evaluated by fitting the charge transfer resistance (Rct) data in the presence of ferric-ferrous hexacyanide redox couple solution, [Fe(CN)6]3-/4-. The voltammetric behavior of norepinephrine (NOR) was confirmed to follow an irreversible reaction mechanism at which the estimated diffusion coefficient value was 7.39 × 10-5 cm2/s. The sensor showed a large enhancement on NOR oxidation and comparatively lowered its detection limit (DL3s) to 0.130 mM (22 ppb). It was also applied for selective determination of NOR in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The interference study highlighted the great stability of the proposed sensor by generating a similar sensitivity as in the pure NOR solution. The analytical performance of the proposed system was validated successfully for pharmaceutical and biological samples with tolerable recovery percentages.

Travelling Wave Solutions for Fisher’s Equation Using the Extended Homogeneous Balance Method

In this work, the extended homogeneous balance method is used to derive exact solutions of nonlinear evolution equations. With the aid of symbolic computation, many new exact travelling wave solutions have been obtained for Fisher’s equation and Burgers-Fisher equation. Fisher’s equation has been widely used in studying the population for various systems, especially in biology, while Burgers-Fisher equation has many physical applications such as in gas dynamics and fluid mechanics. The method used can be applied to obtain multiple travelling wave solutions for nonlinear partial differential equations.

Parasitic Contamination of Local Drinking Water Sources in Aba Metropolis, Abia State, Nigeria

Water-borne parasitic infections have become a source of concern in recent times due to the contamination of various water sources. A survey on the parasitic contamination of local drinking water sources in Aba metropolis was carried out between August and October 2018. This was done to evaluate the extent of contamination of these water sources and their public health implications. A total number of eighty (80) water samples were investigated from five (5) major water sources within the study area using the standard sedimentation method and examined for parasite cysts, eggs and larvae. Physical/macroscopic examination was done to determine the pH, colour, odour, temperature and presence/absence of particles. Among the water sources analyzed, stream water samples had the highest rate of parasite contamination 27 (44.3%) followed by river water 14 (22.9%) while the least contaminated was borehole 7 (11.5%). Rainwater was found free from parasitic infestation. The differences in the level of contamination among the water sources analyzed were found to be statistically significant (P<0.05). Five parasites Entamoeba histolytica, Giardia lamblia, Ascaris lumbricoides of Entamoeba coli and Hookworm were observed. Each of the sample sources except rainwater harbored at least one of these. Among these parasites, Giardia lamblia had the highest rate occurrence of 15 (24.6%), followed by Entamoeba histolytica 14 (22.9%) and the least frequently occurring parasite was hookworm 8 (13.1%). Most of the identified water sources are utilized by the populace who lack access to potable water. The detection of protozoan and helminthic parasites in drinking water sources is a serious public health concern, hence the proper implementation of a supply of safe drinking water is vital.

Magnetization Dynamics in a Perpendicular Anisotropy Free Layer under a Spin Torque Effect with Crossed Polarization

The transfer of spin angular momentum from a spin polarized current provides an efficient way of reversing the magnetization direction of the free layer of the magnetic tunnel junction (MTJ), and while faster reversal will reduce the switching energy, this in turn will lead to low power consumption. In this work, we propose a design where a spin torque oscillator (STO) is integrated with a conventional magnetic tunnel junction (MTJ) which will assist in the ultrafast reversal of the magnetization of the free layer of the MTJ. The structure formed (MTJ stacked with STO), will have the free layer of the MTJ sandwiched between two spin polarizer layers, one with a fixed magnetization direction perpendicular to film plane (main static polarizer) and the other with an oscillatory magnetization (dynamic polarizer). The static polarizer is the fixed layer of the MTJ itself and the dynamic polarizer is the free layer of the STO.

Effect of Smokeless Tobacco Product, Afzal, on the Reproductive Hormones and Gonadal Pathology of Wistar Rats

Afzal is a common smokeless tobacco product (STP) in Oman, and it is believed to contain toxins that may affect the reproductive hormones and hence reproductive function. This study assessed the effect of Afzal on the gonads of Wistar rats. In order to assess gonad toxicity induced by this STP, an aqueous extract of Afzal was added to drinking water to be administrated orally to Wistar albino rats (n = 72) classified as young (4 weeks old) and adult (20 weeks old) of both genders weighing between 60-80 g and 150-240 g respectively for 8 weeks. The rats were divided into 3 groups; control (received distilled water instead of Afzal extract), low-dose (received 3 mg nicotine/kg body weight/day) and high-dose (received 6 mg nicotine/kg body weight/day). At the termination of the study, the rats were euthanized and their blood samples and ovaries were collected for biochemical and histopathological investigations. Testosterone and estradiol hormones showed a significant decrease (P<0.05( in Afzal-treated groups (low and high doses) compared with the control. Histopathological findings revealed the damaging effects manifested as a reduction in the number of the germ cells with deformed organization and in fatty and fibrous degenerations in testes and ovaries. Afzal was found to have adverse effect on the reproductive hormones and gonadal pathology in Wistar rats of both genders, and hence users of Afzal need to consider the risk associated with its frequent use.

Dimension Reduction and Relaxation of Johnson’s Method for Two Machines Flow Shop Scheduling Problem

The traditional dimensionality reduction methods can be generally classified into Feature Extraction (FE) and Feature Selection (FS) approaches. The classical FE algorithms are generally classified into linear and nonlinear algorithms. Linear algorithms such as Principal Component Analysis (PCA) aim to project high dimensional data to a lower-dimensional space by linear transformations according to certain criteria. The central idea of PCA is to reduce the dimensionality of the data set consisting of a large number of variables. In this paper, PCA was used to reduce the dimension of flow shop scheduling problems. This mathematical procedure transforms a number of (possibly) correlated jobs into a smaller number of uncorrelated jobs called principal components, which are the linear combinations of the original jobs. These jobs are carefully determined so that from the solution of the reduced problem multiple solutions of the original high dimensional problem can readily be obtained, or completely characterized, without actually listing the optimal solution(s). The results show that by fixing only some critical jobs at the beginnings and ends of the sequence using Johnson's method, the remaining jobs could be arranged in an arbitrary order in the remaining gap without violating the optimality condition that also guarantees minimum completion time. In this regard, Johnson's method was relaxed by terminating the listing of jobs at the first/last available positions when the job with minimum processing time on either machine attains the highest processing time on the other machine for the first time. By terminating Johnson's algorithm at an early stage, the method minimizes the time needed for sequencing those jobs that could be left arbitrarily. By allowing these jobs to be arranged in arbitrary order it gives job sequencing freedom for job operators without affecting minimum completion time. The results of the study were originally obtained for deterministic scheduling problems but they are more relevant on test problems randomly generated from uniform distribution with lower bound and upper bound and normal distribution with mean and standard deviation .