Fares Ahmed

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Structural change induced on an atomie scale by equilibrium sulphur segregation in tilt germanium grain boundaries

Philosophical Magazine Part B, 2001

2001) Structural change induced on an atomie scale by equilibrium sulphur segregation in tilt ger... more

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Effects of curing temperature and superplasticizer on workability and compressive strength of self-compacting geopolymer concrete

This experimental work focuses on the effects of super plasticizer and curing temperature on the ... more This experimental work focuses on the effects of super plasticizer and curing temperature on the workability and compressive strength of self-compacting geopolymer concrete (SCGC). SCGC is an improved way of concreting execution that does not require compaction and is made by complete elimination of ordinary portland cement content. The parameters investigated were superplasticizer (SP) dosage and curing temperature. SCGC were synthesized from low calcium fly ash, activated by combinations of sodium hydroxide and sodium silicate solutions, and by incorporation of superplasticizer for self compactability. The SP dosages were 3%, 4%, 5%, 6% and 7% and the different curing temperatures were 60 o C, 70 o C, 80 o C and 90 o C. The effects of SP dosage on workability properties such as filling ability, passing ability and resistance to segregation were evaluated. The fresh properties were measured using slump flow, T-50 V-funnel, L-Box and J-ring test methods. The essential workability requirements for self compactability according to European Federation of National Associations Representing Producers and Applicators of Specialist Building Products for Concrete (EFNARC) were satisfied. Results showed that the workability and compressive strength improved with the increase in Super plasticizer dosage. An increase in strength was observed with the increase in curing temperature up to 70 o C. However, the strength decreased when the curing temperature increased beyond 70 o C. The compressive strength of 51.52MPa was obtained for SCGC with SP dosage of 6% and cured at 70 o C oven temperature.

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Unsteady flow simulation of the Ahmed reference body using a lattice Boltzmann approach

Computers & Fluids, 2006

The Ahmed reference body represents a simplified car geometry that can be used to investigate the... more The Ahmed reference body represents a simplified car geometry that can be used to investigate the main flow features in the wake of vehicles. The present work presents unsteady flow simulations at the rear slant angles 25°and 35°using the PowerFLOW 4.0 D3Q19 lattice Boltzmann model. The flow of the wake is discussed and distributions of averaged pressure and velocities are compared with available experimental findings. The resolution requirement is investigated in terms of computational requirement and accuracy achieved. The predictive capability and the feasibility of the very large eddy simulation (VLES) approach within the lattice Boltzmann framework is demonstrated.

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Percutaneous Balloon Mitral Commissurotomy During Pregnancy

Angiology, 2001

Percutaneous balloon mitral commissurotomy was performed in 16 pregnant women aged 23 +/- 3 years... more Percutaneous balloon mitral commissurotomy was performed in 16 pregnant women aged 23 +/- 3 years (range, 16-39 years) who had severe mitral stenosis at pregnancies of mean gestational age 25 +/- 6 weeks. Ten patients were in New York Heart Association functional class III, and six patients were in functional class IV at the time of the procedure. All patients were symptomatic despite maximal medical therapy. The procedure was performed with the Inoue balloon. The mitral valve area increased from 0.9 +/- 0.3 to 1.8 +/- 0.3 cm2 (p &lt; 0.05). The mitral valve pressure gradient decreased from 23 +/- 7 to 6 +/- 3 mm Hg (p &lt; 0.05). The left atrial pressure decreased from 28 +/- 8 to 10 +/- 4 mm Hg (p &lt; 0.05). The pulmonary artery pressure decreased from 59 +/- 18 to 33 +/- 12 mm Hg (p &lt; 0.05). Fourteen patients continued their pregnancies to mean gestational age 37 +/- 2 weeks; all infants were healthy. Two patients had premature deliveries more than 1 month after the procedure due to obstetrical reasons. The two newborns died at day 2 of respiratory distress. Eleven women had vaginal deliveries and five had cesarean sections. All clinically improved to New York Heart Association functional class I or II. Excessive blood loss from the femoral puncture site that required transfusion occurred in one patient. Mitral regurgitation increased one degree in four patients, from 0 to 1+. Patients were observed until delivery. None had restenosis. The degree of mitral regurgitation remained unchanged. Percutaneous balloon mitral commissurotomy can be performed safely during pregnancy. It will effectively improve hemodynamics and symptoms in pregnant patients who have severe mitral stenosis and persistent congestive heart failure symptoms despite conventional medical treatment. There are no immediate detrimental effects of radiation on the fetus. Risks are lower than previously reported when surgical commissurotomy was performed.

Simulation of the opti-physical parameters of selectives surfaces of absorber by the FDTD method. «applied to solar water heater

Energy Procedia, 2011

Solar collectors are used for domestic water heating. They are used to collect and convert solar ... more Solar collectors are used for domestic water heating. They are used to collect and convert solar radiation into heat energy, by heating liquid water. One of the most important components of the solar collector is the absorber, which has to have selectivity in the wavelengths of the solar spectrum. This selectivity allows it to have a maximum of absorbance with a minimum of thermal radiation emitted .The objective of our work consists in characterizing these selective surfaces. A selective surface usually consists of a layer or a thin absorbing film in the solar and transparent spectrum in thermal infrared on a metallic support of a weak emission (substratum). We are interested in our work by the simulation of the opti-physical parameters of these selective surfaces using the FDTD method.

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Water issues in Kuwait: a future sustainable vision

International Journal of Environmental Studies, 2009

... ALI MOHAMED AL-DAMKHI*, RANA ABDULLAH AL-FARES, KHALIFA AHMED AL-KHALIFA§ AND SABAH AHMED A... more

Distribution of income and the income tax burden in Bulgaria

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A method for evaluation of the three-center two-electron integrals over slater type functions

In present work, the three-center two-electron integral [1] has been computed by expanding the tw... more

Search for diphoton events with large missing transverse momentum in 7 TeV proton-proton collision data with the ATLAS detector

Physics Letters B, 2012

A search for diphoton events with large missing transverse momentum has been performed using prot... more A search for diphoton events with large missing transverse momentum has been performed using proton-proton collision data at √ s = 7 TeV recorded with the ATLAS detector, corresponding to an integrated luminosity of 4.8 fb −1 . No excess of events was observed above the Standard Model prediction and model-dependent 95 % confidence level exclusion limits are set. In the context of a generalised model of gauge-mediated supersymmetry breaking with a bino-like lightest neutralino of mass above 50 GeV, gluinos (squarks) below 1.07 TeV (0.87 TeV) are excluded, while a breaking scale Λ below 196 TeV is excluded for a minimal model of gauge-mediated supersymmetry breaking. For a specific model with one universal extra dimension, compactification scales 1/R < 1.40 TeV are excluded. These limits provide the most stringent tests of these models to date.

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The structure of incomes and social protection during the transition: The case of Bulgaria

Europe-asia Studies, 1996

... 632 FAREED MA HASSAN &amp;amp; KYLE PETERS, JR ... In 1992 nearly half (40%) of average h... more

Reviews on books, internet and scientific media

Environmental Earth Sciences, 2010

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Apoptosis as a Form of Cell Death in Intracerebral Hemorrhage

Neurosurgery, 2003

The goals of this study were to identify and quantify the presence of programmed cell death (apop... more The goals of this study were to identify and quantify the presence of programmed cell death (apoptosis) in intracerebral hemorrhage (ICH) among human subjects. Recent evidence from laboratory models suggests that cell death in the perihematoma region may involve apoptosis. Retrospective clinical and histological analyses were performed for patients with spontaneous ICH who underwent surgical evacuation. Quantification of apoptotic cells was performed in sections obtained from the perihematoma region from 12 patients with ICH and stained with the terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling method. Necrosis was identified on the basis of morphological criteria, using hematoxylin and eosin staining. Evidence of apoptosis was present in surgical specimens obtained from 10 of the 12 patients. The mean number of apoptotic cells in the perihematoma region in each patient specimen was 38% (range, 0-90%). For five patients, more than one-half of the total cells observed were apoptotic. Apoptosis was observed in specimens obtained within 1 day, 2 days, and 5 days after the onset of symptoms. No terminal deoxynucleotidyl transferase-mediated deoxyuridine 5-triphosphate nick-end labeling-positive cells were observed in specimens from the two patients with cerebellar hematomas. The mean proportion of necrotic cells in the perihematoma region in each patient specimen was 25% (range, 0-100%). There was a prominent excess of apoptotic cells, in comparison with necrotic cells, for 6 of the 12 patients who underwent hematoma evacuation. For five other patients, similar proportions of apoptotic and necrotic cells were observed. Necrosis was the predominant finding for only one patient, who underwent late surgical evacuation on Day 5. These observations suggest that apoptosis represents a prominent form of cell death associated with ICH in the perihematoma region. Further studies are required to define the mediators of apoptosis in ICH.

Late Onset Ommaya Reservoir Infection Due to Staphylococcus aureus: Case Report and Review of Ommaya Infections

Journal of Infection, 2003

The Ommaya reservoir system has been used for the treatment of chronic central nervous system inf... more The Ommaya reservoir system has been used for the treatment of chronic central nervous system infections and intracranial tumors for more than three decades. The majority of reported Ommaya reservoir infections occur proximate to the time the device is accessed. A review of the literature reveals that late onset of reservoir infection is quite rare. We report a case of Ommaya reservoir infection due to Staphylococcus aureus that was diagnosed seven years after its insertion and usage for intracerebral non-Hodgkin&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s lymphoma and review the literature on the microbiology and management of Ommaya reservoir infections.

Personal Income Tax Reform and Revenue Potential in Transition

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042) Tolerance profile of azathioprine in Crohn’s disease

Arab Journal of Gastroenterology, 2009

6 % Vs Group II = 31.4% (p > 0.05).

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Structural adjustment and family policy in Africa: Lessons from Sudan

Day Care & Early Education, 1996

The economic strategy pursued by a country profoundly influences the well-being of families. This... more The economic strategy pursued by a country profoundly influences the well-being of families. This article uses a social accounting model of the Sudanese economy to compare the effects of two alternative development strategies on growth, employment, and income distribution. The first strategy considered is a conventional growth-oriented strategy emphasizing irrigated, export-oriented agriculture and modern, capital-intensive industry; the second one is a traditional agriculture-led development (TALD) strategy focused on enhancing equity and improving family nutrition by expanding food production. The study's findings for Sudan demonstrate that there is no necessary trade-off between growth and equity. The TALD strategy fosters income growth for the most vulnerable families while simultaneously maximizing aggregate growth. It also holds the prospect of enhancing family equity and increasing access to traditional institutions that provide support to families.

The Long-run and Short-run Endogeneity of Money Supply in Pakistan: An Empirical Investigation

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Sustaining a Common Future

Reviews on books, internet and scientific media

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Economic reform: Is it hurting the poor? A country specific study

Journal of International Development, 1997

Abstract This paper analyses how and why the welfare of the poor in Sudan has changed during the ... more

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