Numerical Simulation of Electric Field and Charge Structure within an Isolated Thunderstorm

The study of electrical structure of thunderstorm is a deterministic factor in characterizing the behavior of lightning. It is impossible to measure the value of electric field at every point within the thunderstorm, even when the in situ measurements are made, they are done along the path of balloon-borne instruments or other methods employed in the measurement. The average data obtained from past measurements were employed in determining the electric field generated by the thunderstorm as observed along the horizontal distance using the cylindrical charge model. The data consisted of a screening charge layer firstly located “between” 1.8-2.0 km and later between 10.0-10.2 km respectively above the ground level (agl) to see the effect of positioning on the resultant computation. The lower positive charge center with radius ranging from 0.5 km to 2.0 km was placed at various heights between 2.0 and 6.0 km. This is to determine the effect of cloud base height on the resulting field profile. The main negative charge is accommodated between 4.0 and 7.5 km and the upper positive charge layer existed between 7.5- 10.0 km agl for a cloud base height of 2.0 km and 6.0- 9.5 km agl for a negative charge layer, 7.5- 11.0 km agl for upper positive charge with a cloud base of 4.0 km high. The resulting potential gradient (PG) profiles were obtained for spatial distribution with screening charge layer playing no active role in the thunderstorm electrification. The effects of wind shear due to increasing wind speed with height were also investigated to have a clear picture of the cloud charge dynamics; hence the vertical PG patterns produced by a moving thunderstorm for various cloud cell life-times were modeled. The results showed that a typical tropical thunderstorm can exhibit charge layer more than the normal tripolar structure, and the pocket of lower positive charge can be more than one or larger than the usual size. Wind shear was found to enhance lightning discharges at the surface of charge discontinuities. Keywords: Potential gradient, Wind shear, Cloud charge, Lower positive charge center, Noninductive charging.

One Step Continuous Hybrid Block Method for the Solution of y'''=f(x,y,y',y'')

In this paper, we present a block method for the direct solution of third order initial value problems of ordinary differential equations. Collocation and interpolation approach was adopted to generate a continuous linear multistep method which was then solved for the independent solution to give a continuous block method. We evaluated the result at selected grid points to give a discrete block which eventually gave simultaneous solutions at both grid and off grid points.  The one-step block method is consistent and A -stable, with good region of absolute stability. Experimental results confirmed the superiority of the new scheme over an existing method. Keywords: consistent, convergent, collocation, hybrid points, independent solution, interpolation, zero stabl

PREDICTING PETROLEUM CONSUMPTION USING TRIGONOMETRIC REGRESSION MODEL

This study is used to model and forecast Nigerian motor gasoline consumption using the Trigonometric Regression model which has the capabilities of handling nonlinear time series. The time plot of Nigerian motor gasoline consumption showed the series is nonlinear. The Trigonometric regression model was estimated using the Ordinary Least Square method. From the result, the coefficients of the model influenced Nigerian motor gasoline consumption and a unit increase may lead to an increase or decrease. The values of coefficient of determination (R^2) revealed that the coefficients of the model explained the variations in Nigerian motor gasoline consumption up to 83%. The value of the adjusted coefficient of determination (R ̅^2 ) also revealed that the model is a good fit and has high predictive power. Therefore, the Nigerian motor gasoline consumption forecast from 1980 to 2038 indicated continuous fluctuations from year to year. The shape of the out-sample forecast from 2019 to 2038 exhibited a bell shape. Conclusively, based on the results obtained, the proposed model can be used to obtain future values for Nigerian motor gasoline consumption. This will enhance the Government and shareholders to put in place proper plans and logistics to curtail the challenges that may arise from Nigerian motor gasoline consumption and distribution presently and in the future

TWO STEPS BLOCK METHOD FOR THE SOLUTION OF GENERAL SECOND ORDER INITIAL VALUE PROBLEMS OF ORDINARY DIFFERENTIAL EQUATION

In this paper, an implicit block linear multistep method for the solution of ordinary differential equation        was extended to the general form of differential equation. This method is self starting and does not        need   a   predictor   to   solve   for   the   unknown   in   the   corrector.   The   method   can   also   be   extended   to        boundary   value   problems  without   additional   cost.   The  method was   found to   be  efficient   after   being        tested with numerical problems of second order

Oscillatory dissipative conjugate heat and mass transfer in chemically-reacting micropolar flow with wall couple stress : a finite element numerical study

High temperature non-Newtonian materials processing provides a stimulating area for process engineering simulation. Motivated by emerging applications in this area, the present article investigates the time-dependent free convective flow of a chemically-reacting micropolar fluid from a vertical plate oscillating in its own plane adjacent to a porous medium. Thermal radiative, viscous dissipation and wall couple stress effects are included. The Rosseland diffusion approximation is used to model uni-directional radiative heat flux in the energy equation. Darcy’s model is adopted to mimic porous medium drag force effects. The governing two-dimensional conservation equations are normalized with appropriate variables and transformed into a dimensionless, coupled, nonlinear system of partial differential equations under the assumption of low Reynolds number. The governing boundary value problem is then solved under physically viable boundary conditions numerically with a finite element method based on the weighted residual approach. Graphical illustrations for velocity, micro-rotation (angular velocity), temperature and concentration are obtained as functions of the emerging physical parameters i.e. thermal radiation, viscous dissipation, first order chemical reaction parameter etc. Furthermore, friction factor (skin friction), surface heat transfer and mass transfer rates have been tabulated quantitatively for selected thermo-physical parameters. A comparison with previously published paper is made to check the validity and accuracy of the present finite element solutions under some limiting cases and excellent agreement is attained. Additionally, a mesh independence study is conducted. The model is relevant to reactive polymeric materials processing simulation

Prevalence Rates of Mental Disorders in Chilean Prisons

PMCID: PMC371883

ISOLATION AND CHARACTERIZATION OF CHEMICAL CONSTITUENTS FROM Chrysophyllum albidum G. DON-HOLL. STEM-BARK EXTRACTS AND THEIR ANTIOXIDANT AND ANTIBACTERIAL PROPERTIES

Background: The plant, Chrysophyllum albidum is indigenous to Nigeria and its stem-bark has found relevance in folkloric medicine for infections and oxidative stress linked diseases medicaments. The study targets to isolate the chemical constituents accountable for the antioxidant and antibacterial actions of the plant stem-bark to substantiate some of its ethnomedicinal uses. Materials and Methods: Stem-bark extract of Chrysophyllum albidum was obtained from 80 % ethanol was partitioned in sequence with ethyl acetate (EtOAc) and n-butanol. The solvent fractions and isolated compounds were verified for antioxidant chattels utilizing 2-2-diphenyl-1-picrylhydrazyl. Antibacterial actions were also assessed by agency of agar-diffusion and broth micro dilution methods. EtOAc fraction was on many occasions chromatographed on silica and Sephadex LH-20 column to afford four compounds and their chemical structures were proven with the employment of NMR (1D and 2D) and MS. Results: Chromatographic fractionation of EtOAc fraction with the premier antioxidant and antimicrobial activities afforded stigmasterol (1), epicatechin (2), epigallocatechin (3) and procyanidin B5 (4). Procyanidin B5 isolated for the first time from Chrysophyllum genus proven the supreme antioxidant activity with IC50 values of 8.8 µM and 11.20 µM in DPPH and nitric oxide assays respectively and equally established the ultmost inhibitory activity against Escherichia coli (MIC 156.25 μg/mL), Staphylococcus aureus (MIC 156.25 μg/mL), Pseudomonas aeruginosa (MIC 625 μg/mL) and Bacillus subtilis (MIC 156.25 μg/mL). Conclusion: The antibacterial and antioxidant activities of epicatechin, epigallocatechin and procyanidin B5 isolated from Chrysophyllum albidum stem-bark substantiate the folkloric use

IGF1 activates cell cycle arrest following irradiation by reducing binding of ΔNp63 to the p21 promoter

Radiotherapy for head and neck tumors often results in persistent loss of function in salivary glands. Patients suffering from impaired salivary function frequently terminate treatment prematurely because of reduced quality of life caused by malnutrition and other debilitating side-effects. It has been previously shown in mice expressing a constitutively active form of Akt (myr-Akt1), or in mice pretreated with IGF1, apoptosis is suppressed, which correlates with maintained salivary gland function measured by stimulated salivary flow. Induction of cell cycle arrest may be important for this protection by allowing cells time for DNA repair. We have observed increased accumulation of cells in G2/M at acute time-points after irradiation in parotid glands of mice receiving pretreatment with IGF1. As p21, a transcriptional target of the p53 family, is necessary for maintaining G2/M arrest, we analyzed the roles of p53 and p63 in modulating IGF1-stimulated p21 expression. Pretreatment with IGF1 reduces binding of ΔNp63 to the p21 promoter after irradiation, which coincides with increased p53 binding and sustained p21 transcription. Our data indicate a role for ΔNp63 in modulating p53-dependent gene expression and influencing whether a cell death or cell cycle arrest program is initiated

Radiative and magnetohydrodynamics flow of third grade viscoelastic fluid past an isothermal inverted cone in the presence of heat generation/absorption

A mathematical analysis is presented to investigate the nonlinear, isothermal, steady-state, free convection boundary layer flow of an incompressible third grade viscoelastic fluid past an isothermal inverted cone in the presence of magnetohydrodynamic, thermal radiation and heat generation/absorption. The transformed conservation equations for linear momentum, heat and mass are solved numerically subject to the realistic boundary conditions using the second-order accurate implicit finite-difference Keller Box Method. The numerical code is validated with previous studies. Detailed interpretation of the computations is included. The present simulations are of interest in chemical engineering systems and solvent and low-density polymer materials processing

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially