Journal of Basic and Applied Sciences  -   Volume 8 Number 2

The Bi-Gamma ROC Curve in a Straightforward Manner

Ehtesham Hussain

http://dx.doi.org/10.6000/1927-5129.2012.08.02.09

Abstract: In biomedical research, biomarkers (diagnostic tests) are used in distinguishing healthy and diseased populations. The effectiveness and accuracy of a biomarker generally assessed through the use of a Receiver Operating Characteristic (ROC) curve model, and its functional such as area under the curve (AUC). The parametric (smooth) ROC curves are obtained under the specific distributions assumptions. A resulting ROC curve model is the plot of sensitivity versus 1-specificity for all possible threshold values. Most popular and widely used ROC curve model is bi-normal ROC curve model under the assumptions of normality. When the biomarker results are continuous and positively skewed (non-normal). The gamma distribution is supposed to a flexible model for positively skewed measurements. In practice use of bi-gamma ROC curve model is hindered by the fact that ROC function cannot be written in closed-form.

The solution of the problem is to use transformed invariance property of ROC curve model. Which assumes that the test results of both diseased and healthy are normally distributed after some monotone transformation [1].

In this paper we propose a simple approximation solution for the problem mentioned in above lines using a normal approximation due to Wilson and Hilfertys [2]. Which is useful to approximate gamma distribution results with classical normal distribution based results.

Keywords: Sensitivity, Specificity, Receiver Operating Characteristic (ROC) curve, Normal distribution, Gamma distribution

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Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Heavy Protein Alteration under the Effects of Lead Acetate in Bactrocera cucurbitae

Rizwanul Haq, M. Farhanullah Khan and Ehteshamul Haq

http://dx.doi.org/10.6000/1927-5129.2012.08.02.07

Abstract: Lead is supposed to be an important poisonous waste which could contaminate the environment, therefore, insects could be influenced easily by the lead., Bactrocera cucurbitae was studied at 48 hours post treatment, under the effects of lead acetate, in different concentrations of 0.125 mg., 0.25 mg., 0.5 mg, 1.0 mg and 2.0 mg. It was observed that under the effects of lead abnormalities and deformity were developed in the larvae of flies. Thus these flies could present a useful module for the quick transmission of the environmental hazards due to lead contamination, which exerts a specific physiological and morphological effect on these flies.

Keywords: Effects, Lead acetate, Proteins Bactrocera cucurbitae

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Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Experimental Study on the Morphology of Keratin Based Material for Asbestos Free Brake Pad

O.S. Olokode, S.O. Fakolujo, P.O. Aiyedun, Z.O. Jaji, F.T. Owoeye and B.U. Anyanwu

http://dx.doi.org/10.6000/1927-5129.2012.08.02.08

Abstract: This research was carried out to investigate the friction and wear of automotive materials using a pad on disk type friction tester to study the synergistic effects of bagasse (residue from sugarcane) and cow hooves dust (keratin based material). The friction materials were based on a simple formulation with three ingredients (phenolic resin, cow hooves dust and bagasse). Friction stability, hardness, compressive strength, flame resistance and oil absorption were measured. Microscopic observation of the friction material showed that the cow hooves adhered to the bagasse providing heat resistance and strength to the friction film at the rubbing interface. The beneficial synergistic effect from the two fibrous ingredients however was significantly diminished when only one of them was employed.

Keywords: Hardness, compressive strength, cow hooves, Bagasse

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Journal of Basic and Applied Sciences  -   Volume 8 Number 2

Effects of Lead Acetate on Morphology of Musca domestica L. (Muscidae: Dipptera)

Rizwanul Haq, M.farhan Ullah Khan and Ehtesham ul Haq

http://dx.doi.org/10.6000/1927-5129.2012.08.02.06

Abstract: Lead is significant environmental pollutant which contaminates food, soil, water, and air. Insects too are influenced easily by such pollutants, therefore present study have been designed to study the influence of lead (as lead acetate) on external morphology of Musca domestica. The different concentrations of lead acetate, i.e., 0.25 mg., 0.5 mg, and 01 mg per ml in diet of Musca domestica, were added ad effects were observed after 48 hours. Results revealed that in addition to abnormalities and malformation the larvae, morphological changes in adults were observed such as elongated and de-shaped wings and elongated and folded legs. Some other structural abnormalities of larvae and pupal shape were also observed (tell briefly what were those changes. Thus the Diptera flies present a useful model for the rapid screening of the environmental hazards due to lead contamination, which exerts a definite physiological and morphological effect on these flies.

Keywords: Heavy metal, lead acetate, M. domestica

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