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Search Results: 1 - 10 of 401736 matches for " M. Umar "
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Clinical Isolates of Staphylococcus aureus Show Variation in β-Lactamase Production and Are More Susceptible to Antibiotics Conjugated with β-Lactamase Inhibitors  [PDF]
Uzal Umar, Umar Ahmed Faruk, Damoroem M. Tanko, Mohammed B. Yerima
Open Journal of Medical Microbiology (OJMM) , 2016, DOI: 10.4236/ojmm.2016.64019
Abstract: β-Lactam antibiotics are a cornerstone in the treatment of bacterial infections on account of its high therapeutic index and selective toxicity—they act by inhibiting the biosynthesis of peptidoglycan, a key component in bacterial cell wall. Ninety (90) clinical specimens obtained from the microbiology unit Specialist Hospital Bauchi were screened for S. aureus, positive isolates were examined for β-Lactamase expression by using two Penicillin G concentrations (5000 IU/ml and 25,000 IU/ml) in acidometric agar technique with phenol red as indicator, and the susceptibility pattern of the isolates to β-Lactam antibiotics was also determined. S. aureus prevalence of 31% (28/90) was obtained, of which 96% (27/28) of strains were β-Lactamase positive in the standard test, while 63% (17/27) were able to hydrolyze penicillin G concentration of 25,000 IU/ml (5X the concentration in the standard test), and a strain was found to be β-Lactamase negative. The resistance to five β-Lactams, ampicillin, cephalexin, amoxicillin, cloxacillin and flucloxaillin, were 100%, 96%, 89
Influence of Environmental Pollution on the Transmission Dynamics of Infection
M.A. Umar
Research Journal of Applied Sciences , 2012,
Abstract: In this research, we examined the relationship between pollution and infection and proposed pollution/transmission dynamics model for infection, in an age-structured population. Other factors such as population growth in the present of pollution and transmission rate are discussed. It is observed that pollution increases the mortality rate and thus reduce life expectancy of those within the location. However it is independent of infection, but helps to accelerate transmission rate for the infection. The existence of the non-triavial steady states is examined and their stability discussed.
Effect of Vaccination, Treatment and Population Area Size on the Transmission Dynamics of Tuberculosis in a Proportionate Mixing Population
M.A. Umar
Research Journal of Applied Sciences , 2012,
Abstract: We have examined the effect of vaccination, treatment and population area size on the transmission dynamics of tuberculosis, in a proportionate mixing population with vital dynamics, where the vaccine is assumed to be leaking, so that vaccinated individuals progress to the infectives population, when in contact with the disease. Three subs-models for the transmission dynamics of the disease are proposed and the influence of the population area size on each are examined via the basic reproductive number of the disease and the determinant, trace stability conditions. The non trivial equilibrium states are obtained and their stability discussed.
Comparative Study of Holt-Winter, Double Exponential and the Linear Trend Regression Models, With Application to Exchange Rates of the Naira to the Dollar
M.A. Umar
Research Journal of Applied Sciences , 2012,
Abstract: In this study, we examined the Holt-winter, double exponential and the linear regression trend parameter estimation techniques and compare their forecast quality via the criteria of forecast as in Gilchrist, using time s series data of exchange rates of the Naira to the dollar. Forecasts using these methods are presented and comparison statistics and statistics of errors for the methods are examined. It is found that the Holt-winter forecasting method with choice of smoothening constant a = 0.2 and b = 0.5 produced better forecasts than the rest of the methods. In general, the Holt-winter always gives outstanding forecasts than the other methods, as seen on the table of comparison statistics and statistics of error. Also, the required constraint on the smoothening constants for the Holt-winter to meet the criteria of forecast is suggested.
The Role of Speculation in the Determination of Energy Prices
Umar M. Mustapha
International Journal of Energy Economics and Policy , 2012,
Abstract: This paper seeks to evaluate the role of speculation in the determination of global energy prices. Designed as a case study, five major oil producing countries are the focus of this positivistic study: Nigeria, Mexico, Iran, Saudi Arabia and Russia. Data is collected through secondary sources. One-tailed and two-tailed tests carried out on the relationship between speculation and oil prices for each of the five countries yield critical values lower than the alpha. Thus, the null hypothesis is rejected in favor of the alternate hypothesis that ‘there is a significant and positive correlation between commodity derivatives (oil futures) and oil prices’. The study found that while there is a positive relationship between speculation in the commodity derivatives market and oil prices, such a relationship is at best weak and attributes the high prices to several factors, including political instability, high and rising demand from overheating economies such as China, and falling production levels, among others. The paper emphasized the need to enhance the physical and financial transparency of the energy market, as well as the operation of the supply and demand fundamentals, including regulating against insider trading and market manipulation practices, strengthening the reporting requirements of the dealers in the market, and strengthening capital adequacy and margin requirements.
Purification and Some Properties of Acid Protease from Penicillium expansum
M. Umar Dahot
Journal of Applied Sciences , 2001,
Abstract: An acid protease was isolated from the culture broth of Penicillium expansum grown on rice husk (40 mesh fine powder) mineral medium. The protease enzyme was purified on Sephadex G-100 and DEAE Sephdex A-50 with recovery of 7.52%. Purified enzyme shows a single band on SDS polyacrylamide gel electrophoresis. The optimum activity of protease was found at pH 3.5 and temperature 30oC. The activation energy for the hydrolysis of casien by acid protease was 93 KJ/mol. The enzyme activity was highly increased in the presence of CoCl2 (71.57%), cysteine (54.23%), mercaptoethanol (44.70%), ZnCl2 (34.78%) but slightly activated by CaCl2 (10.24%) and MnCl2 (1.37%). Whereas protease activity was reduced on the addition of EDTA (55.88%), AgNo3 (67.85%) and HgNO3)2 (64.71%). The thermal stability of protease was increased in the presence of ZnCl2. The half-life of acid protease in the absence and presence of ZnCl2 at 50oC was determined 17 and 28 minutes respectively.
Two-body dissipation effects on synthesis of superheavy elements
M. Tohyama,S. Umar
Physics , 2015,
Abstract: To investigate the two-body dissipation effects on the synthesis of superheavy elements, we calculate low-energy collisions of the $N=50$ isotones ($^{82}$Ge, $^{84}$Se, $^{86}$Kr and $^{88}$Sr) on $^{208}$Pb using the time-dependent density-matrix theory (TDDM). TDDM is an extension of the time-dependent Hartree-Fock (TDHF) theory and can determine the time evolution of one-body and two-body density matrices. Thus TDDM describes both one-body and two-body dissipation of collective energies. It is shown that the two-body dissipation may increase fusion cross sections and enhance the synthesis of superheavy elements.
One-Pot Synthesis of Aldol Adduct Catalyzed by Immobilized Picolylamine on Zirconia  [PDF]
Mohammad Sadiq, Razia  , M. Naveed Umar, Gul Zamin
Modern Research in Catalysis (MRC) , 2014, DOI: 10.4236/mrc.2014.31001
Abstract:

Direct aldol reactions have been successfully performed using aromatic aldehyde and cyclic ketone in nonpolar solvent by using immobilized picolylamine on zirconia as a catalyst, in a double walled batch reactor. The prepared catalyst was characterized by SEM, XRD and FT-IR. FT-IR peaks reveal the presence of picolylamine on the surface of zirconia. The catalyst shows excellent catalytic activity in aldol reaction of cyclohexanone with benzaldehyde in cyclohexane giving 2-hydroxyphenylmethylcyclohexanone (55.7% yield) in 4 hr at 80?C. Furthermore, the catalyst is recoverable by simple filtration and could be used several times without significant loss in activity.

A Global Stability Analysis of a Susceptible-Infected-Removed-Prevented-Controlled Epidemic Model  [PDF]
Muhammad A. Yau, Hussaini S. Ndakwo, A. M. Umar
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.510131
Abstract: A mathematical model of HIV transmission dynamics is proposed and analysed. The population is partitioned into five compartments of susceptible S(t), Infected I(t), Removed R(t), Prevented U(t) and the Controlled W(t). Each of the compartments comprises of cohort of individuals. Five systems of nonlinear equations are derived to represent each of the compartments. The general stability of the disease free equilibrium (DFE) and the endemic equilibrium states of the linearized model are established using the linear stability analysis (Routh-Hurwitz) method which is found to be locally asymptotically stable when the infected individuals receive ART and use the condom. The reproduction number is also derived using the idea of Diekmann and is found to be strictly less than one. This means that the epidemic will die out.
Interacting holographic dark energy with logarithmic correction
Mubasher Jamil,M. Umar Farooq
Physics , 2010, DOI: 10.1088/1475-7516/2010/03/001
Abstract: The holographic dark energy (HDE) is considered to be the most promising candidate of dark energy. Its definition is originally motivated from the entropy-area relation which depends on the theory of gravity under consideration. Recently a new definition of HDE is proposed with the help of quantum corrections to the entropy-area relation in the setup of loop quantum cosmology. Using this new definition, we investigate the model of interacting dark energy and derive its effective equation of state. Finally we establish a correspondence between generalized Chaplygin gas and entropy-corrected holographic dark energy.
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