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Robust estimation of multiple linear regression parameters in the presence of a problem of heterogeneity of variance and outliers values

Often times, especially in practical applications, it is difficult to obtain data that is not tainted by a problem that may be related to the inconsistency of the variance of error or any other problem that impedes the use of the usual methods represented by the method of the ordinary least squares (OLS), To find the capabilities of the features of the multiple linear models, This is why many statisticians resort to the use of estimates by immune methods Especially with the presence of outliers, as well as the problem of error Variance instability, Two methods of horsepower were adopted, they are the robust weighted least square(RWLS)& the two-step robust weighted least square method(TSRWLS), and their performance was verified by applying it to simulate & selection the best methods for estimation by using measures mean absolute percentage error (MAPE) to compare them, the results show the method of (TSRWLS) is the best.

                                                                                                                                                                                                                                       

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Publication Date
Mon Apr 10 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Effect of Doping Cu on the Structural and Optical Properties of (CdTe) Thin Films

   In this research we studied  the structural and optical properties of (CdTe) thin films which have been prepared  by thermal evaporation deposition method on the glass substrate at R.T with thickness (450  25) nm., as  a function of doping  ratio with copper element  in (1,3,5) % rate .The structure  measurement  by X-ray diffraction (XRD) analyses shows that the single phase of (CdTe) with polycrystalline structure with a preferred orientation [111].   The optical  measurement shows that the (CdTe) films have a direct energy gap, and they decrease with the increase of doping ratio reaching to 5% . The optical constants are investigated and calculated, such as absorpti

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Publication Date
Thu Apr 27 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Theory and Calculation of the Reorganization Energy of Electron Transfer at Liquid/Liquid Interface

A description of the theoretical of the reorganization energies have been described  according to the outer-sphere Marcus model .It  is a given expression according this model unable to evaluate the reorganization energy for electron transfer at liquid /liquid interface. The spherical model approach have been used to  evaluate the radius of donor and acceptor liquid alternatively .Theoretical results of  the reorganization free energy for electron transfer at liquid/liquid interface system was  carried out . Matlap program is then used to calculate 𝐸0 for electron transfer reaction between water donor stated and many liquid acceptor state. This shows a good  agreement with the experiment. The results

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Publication Date
Sun Jun 04 2017
Journal Name
Baghdad Science Journal
The efficiency of some plant extracts for growth inhibition of Candida albicans and Trichophytonmentagrophytes

Plant extracts occupied a big place in diseases treatment and preserving human health because, they contain many active substances that can be exploited in the field of pharmaceutical manufacturing from natural materials. Therefore, this study was conducted to evaluate the effect of different concentrations of plant extracts for each of Nigella sativa, Alliumsativum and Allium cepa against the fungal growth of Candida albicans that cause many skin diseases and infections to humans as well as Trichophyton mentagrophytes, which affects the hair, skin and nails. These two fungi have been isolated and diagnosed from people who have skin infection. Both fungal isolates were treated with extracts of Nigella sativa, Alliumsativum and Allium cepa

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Publication Date
Sat Jan 01 2011
Journal Name
Iraqi Journal Of Physics
The Effect of CdCl2 and annealing treatments on structural properties of CdS/CdTe heterojunction

CdS and CdTe thin films were thermally deposited onto glass substrate. The CdCl2 layer was deposited onto CdS surface. These followed by annealing for different duration times to modify the surface and interface of the junction. The diffraction patterns showed that the intensity of the peaks increased with the CdCl2/annealed treatment, and the grain sizes are increased after CdCl2/annealed treatment

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Publication Date
Tue Mar 14 2023
Journal Name
Iraqi Journal Of Science
Inhibitory Effect of Grapefruit Extracts on the Growth and Adhesion Ability of Staphylococcus aureus

Ten isolates belong to the Staphylococcus bacteria from different clinical swabs were taken from patients in Ibn al-Nafis Hospital and Central Public Health laboratory, according to many morphological and biochemical tests that used to identify bacterial species S. aureus, the results showed that 8 isolates when investigated their ability to produce a slime layer using Congo red agar method the results showed that SA5 isolate was the best compared to other isolates through change the color of colonies to the pink and Congo red agar -colored Black.
When examining the inhibitory effect of grapefruit extracts in the growth of isolated bacteria SA5 S.aureus, results showed that the aqueous extract of the seeds at different concentrations

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Publication Date
Sat Jul 01 2023
Journal Name
Journal Of Engineering
Effect of Heat Treatments and Carbon Content on the Damping Properties of Structural Steel

Low- and medium-carbon structural steel components face random vibration and dynamic loads (like earthquakes) in many applications. Thus a modification to improve their mechanical properties, essentially damping properties, is required. The present study focuses on improving and developing these properties, significantly dampening properties, without losing the other mechanical properties. The specimens used in the present study are structural steel ribbed bar ISO 6935 subjected to heating temperatures of (850, 950, and 1050) ˚C, and cooling schemes of annealing, normalizing, sand, and quenching was selected. The damping properties of the specimens were measured experimentally with the area under the curve for the loadi

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Publication Date
Mon Apr 10 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
The Effect of Thickness on Electrical Conductivity and Optical Constant of Fe2O3 Thin Films

   In this research the electrical conductivity and optical measurements were made on the Iron Oxide (Fe2O3) films prepared by chemical spray pyrolysis method as a function of thickness (250, 350, 450, and 550)  20 nm.    The measurements of electrical conductivity (σ), activation energies (Ea1, Ea2),and optical constant such as absorption coefficient, refractive index, extinction coefficient and the dielectric constants for the wavelengths in the range (300-900) nm have been investigated on (Fe2O3) thin films as a function of thickness. All films contain two types of transport mechanisms, and the electrical conductivity (σ) increases whereas the activation energy (Ea) would decrease as the films thi

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Publication Date
Sat Nov 28 2020
Journal Name
Iraqi Journal Of Science
Evaluation of the Biological Activity of Nickel Oxide Nanoparticles as Antibacterial and Anticancer Agents

In the present study, nickel oxide nanoparticles (NiO NPs) were evaluated as an antibacterial and anticancer agent. The nanoparticles of nikel oxide were synthesized using aloe vera leaves extract and characterized with AFM (showing an average diameter of 45.11 nm), XRD and FE-SEM analyses. Three different concentrations (125, 250 and 500 µg/ml) were prepared from the synthesized NiO NPs and investigated for their potential antibacterial activity against both Enterococcus faecalis (Gram-positive bacteria) and Acinobacter baumannii (Gram-negative bacteria). While cytotoxicity and apoptotic activity were measured on both MCF-7 and AMJ13 cancer cell lines by  MTT and caspase-9 luminescence assays. The results showe

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Publication Date
Tue Dec 20 2022
Journal Name
Bulletin Of The Iraq Natural History Museum (p-issn: 1017-8678 , E-issn: 2311-9799)
ECOLOGY OF LEECHES AND GASTROPODS OF THE LOWER AK-BUURA RIVER, FERGANA VALLEY,UZBEKISTAN

This study was conducted on species composition, morphology, ecological characteristics, biotope distribution, ecological groups, biodiversity indicators and zoogeography of leeches and gastropods distributed in the lower Ak-Buura River. According to the results, it was found that 7 species of leeches belonging to 4 families and 6 genera and 10 species of fresh-water gastropods belonging to 3 families and 6 genera live in the lower Ak-Buura River. In the river, it was observed that leeches are mainly distributed in muddy biotopes, and gastropods are widespread in muddy, stony and sandy biotopes with a lot of plants. Biodiversity indices of leeches and gastropods in the Ak-Buura River were analyzed using the Shannon index. As a result, it

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Publication Date
Tue Mar 30 2021
Journal Name
Journal Of Economics And Administrative Sciences
The effect of gender diversity of board directors and accounting conservatism on firm value

The study aims to investigate the relationship between the gender diversity of board director, the accounting conservatism and firm value in Iraqi firms. The sample was represented by 30 Iraqi firms listed on the Iraqi market over the period 2017. The research was based on the main hypothesis that gender diversity has a positive relationship with conservatism and firm value, that conservatism as an intermediate variable will enhance the positive relationship between gender diversity and firm value. The study reached results that support the research hypotheses. The appointment of females to the board helps improve the provision of conservative accounting information and avoids overstate when reporting earnings. Based on these res

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