Papers by Mohamed Amr Ibrahim
2021 IEEE International Symposium on High-Performance Computer Architecture (HPCA), 2021
Graphics Processing Units (GPUs) use caches to provide on-chip bandwidth as a way to address the ... more Graphics Processing Units (GPUs) use caches to provide on-chip bandwidth as a way to address the memory wall. However, they are not always efficiently utilized for optimal GPU performance. We find that the main source of this inefficiency stems from the tightly-coupled design of cores with L1 caches. First, such a design assumes a per-core private local L1 cache in which each core independently caches the required data. This allows the same cache line to get replicated across cores, which wastes precious cache capacity. Second, due to the many-to-few traffic pattern, the tightly-coupled design leads to low per-core L1 bandwidth utilization while L2/memory is heavily utilized.To address these inefficiencies, we renovate the conventional GPU cache hierarchy by proposing a new DC-L1 (DeCoupled-L1) cache – an L1 cache separated from the GPU core. We show how decoupling the L1 cache from the GPU core provides opportunities to reduce data replication across the L1s and increase their band...
Political Institutions: Non-Democratic Regimes eJournal, 2013
This study empirically estimates the critical parameters of private sector demand determinants fo... more This study empirically estimates the critical parameters of private sector demand determinants for employment in Egypt by using annual time series-cross section data (1990-2007) and by applying a fixed effects panel Seemingly Unrelated Regression (SUR) model. The empirical results confirm that, in both long run and short run, there are positive and significant relationship between the private demand for employment and real private domestic product and real private investment. On the other hand, there is unexpected positive and significant relationship between the private demand for employment and the real wages in the long run, and negative and insignificant relationship in the short run. The study also confirm that, if private demand for employment is one percent out of equilibrium, a 44 percent adjustment towards equilibrium will take place within the first year.
Arguments on dollarization and its effect on the economy have been published mainly on economics ... more Arguments on dollarization and its effect on the economy have been published mainly on economics and financial journals, yet, little is known about Somalia’s unofficial dollarization. To contribute in that matter, this paper presents the effect of dollarization on Somali economy. The study is carried out using literature analysis. The study found out that dollarizing Somali economy brings severe economic turmoil including an absolute failure to achieve price stability in the local market. In addition, adopting this policy impedes achieving strong financial management system in the country. The study recommends that policymakers and business community should try to lessen the reliance on US dollar and encourage the use of a basket of currencies (in the short-run) while strengthening the use of local currency (in the long-run). Adopting such strategy will facilitate to avoid recurrent financial crisis which might happen if the use of US dollar as an internal currency is collapsed.
Proceedings of the ACM International Conference on Supercomputing, 2019
Value prediction holds the promise of significantly improving the performance and energy efficien... more Value prediction holds the promise of significantly improving the performance and energy efficiency. However, if the values are predicted incorrectly, significant performance overheads are observed due to execution rollbacks. To address these overheads, value approximation is introduced, which leverages the observation that the rollbacks are not necessary as long as the application-level loss in quality due to value misprediction is acceptable to the user. However, in the context of Graphics Processing Units (GPUs), our evaluations show that the existing approximate value predictors are not optimal in improving the prediction accuracy as they do not consider memory request order, a key characteristic in determining the accuracy of value prediction. As a result, the overall data movement reduction benefits are capped as it is necessary to limit the percentage of predicted values (i.e., prediction coverage) for an acceptable value of application-level error. To this end, we propose a ...
In this paper, we prove the existence and uniqueness of a nonlinear perturbed stochastic fraction... more In this paper, we prove the existence and uniqueness of a nonlinear perturbed stochastic fractional integro-differential equation of Volterra-Ito type involving nonlocal initial condition by using the theory of admissibility of integral operator and Banach fixed-point principle. Also the stability and boundedness of the second moments of the stochastic solution are studied. In addition, an application to fractional stochastic feedback system is presented.
This research work presents a new implementation of the CMOS electric-field sensor, titled as Dif... more This research work presents a new implementation of the CMOS electric-field sensor, titled as Differential Electric Field Sensitive Field Effect Transistor (DeFET). The DeFET is successfully used in detection of small partials and it is a suitable candidate to be used in biochemical and environmental applications. The developed implementation of the DeFET provides an improved sensitivity, thus it can be used to detect tiny particles in the range of nano meter scale. The direct application of the proposed sensor is the air pollution and environmental detection. The chip is implemented using 180 nm CMOS technology; it contains both the actuation and sensing parts. The sensors are distributed in two different arrays (uniform and nonuniform arrays).
International Journal of Environmental Research and Public Health
Background: Within the UK, COVID-19 has contributed towards over 103,000 deaths. Although multipl... more Background: Within the UK, COVID-19 has contributed towards over 103,000 deaths. Although multiple risk factors for COVID-19 have been identified, using this data to improve clinical care has proven challenging. The main aim of this study is to develop a reliable, multivariable predictive model for COVID-19 in-patient outcomes, thus enabling risk-stratification and earlier clinical decision-making. Methods: Anonymised data consisting of 44 independent predictor variables from 355 adults diagnosed with COVID-19, at a UK hospital, was manually extracted from electronic patient records for retrospective, case–control analysis. Primary outcomes included inpatient mortality, required ventilatory support, and duration of inpatient treatment. Pulmonary embolism sequala was the only secondary outcome. After balancing data, key variables were feature selected for each outcome using random forests. Predictive models were then learned and constructed using Bayesian networks. Results: The propo...
Medicina
Background and objectives: The primary objective was to evaluate the benefit of training with vir... more Background and objectives: The primary objective was to evaluate the benefit of training with virtual reality simulation. The secondary objective was to describe the short-term skill acquisition obtained by simulation training and to determine the factors affecting its magnitude. Materials and Methods: We prospectively performed a three-stage evaluation: face, constructive, and predictive to evaluate the training with a laparoscopic simulator with haptic feedback. The participants (n = 63) were divided according to their level of experience into three groups: 16% residents; 46% specialists and 38% were consultants. Results: Face evaluation demonstrates the acceptance of the design and realism of the tasks; it showed a median score of eight (IQR 3) on a Likert scale and 54% of participants (n = 34) gave the tissue feedback a moderate rating. Constructive evaluation demonstrates the improvement of the participants in the training session and the ability of the designed task to disting...
Proceedings of the ACM International Conference on Parallel Architectures and Compilation Techniques
A&A Practice
Supplemental Digital Content is available in the text. The coronavirus disease 2019 (COVID-19; SA... more Supplemental Digital Content is available in the text. The coronavirus disease 2019 (COVID-19; SARS-CoV-2) pandemic has created serious challenges to anesthesiologists. As hospitalized patients’ respiratory function deteriorates, many will require endotracheal intubation. Airway management of infected patients risks aerosolization of viral-loaded droplets that pose serious hazards to the anesthesiologist and all health care personnel present. The addition of an enclosure barrier during airway management minimizes the hazard by entrapping the droplets and possibly the aerosols within an enclosed space adding additional protection for health care workers. The aim of this study was to compare the effectiveness of different barrier enclosure techniques during tracheal intubation and extubation.
Horticulture, Environment, and Biotechnology
Aluminium (Al) toxicity in acidic soils limits crop production worldwide. We evaluated eleven gen... more Aluminium (Al) toxicity in acidic soils limits crop production worldwide. We evaluated eleven genotypes of Brassica juncea (Mustard) under Al stress on basis of their growth and shortlisted two best among them for further comparative analysis. Our objective was to elucidate individual and differential oxidative damage and defence response elicited by Al treatment in selected mustard genotypes, ‘Pusa Tarak’ and ‘Pusa Vijay’. Thirty-day-old plants of both genotypes were subjected to Al stress for a period of 24 h and 72 h. Concentration of superoxides was visible much higher in leaves of ‘Pusa Vijay’ both at 24 h and 72 h, also confirmed by oxidative stress marker thiobarbituric acid reactive substances (TBARS). The activities of the enzymatic antioxidants superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione reductase (GR), glutathione S-transferase (GST), and catalase (CAT) were significantly higher in ‘Pusa Tarak’ compared to control and ‘Pusa Vijay’ at both time stages. Levels of non-enzymatic antioxidants glutathiones and ascorbates were already higher in ‘Pusa Vijay’; however, Al treatment increased their levels in both genotypes with non-significant changes on inter-genotypes basis. More and significant decline by Al in chlorophylls was observed in ‘Pusa Vijay’. Interestingly, increase in proline content by Al was much prominent in ‘Pusa Tarak’ compared to ‘Pusa Vijay’. The in vitro antioxidant capacity estimation of mustard genotypes, evaluated by measuring 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and hydroxyl radical scavenging (HRSA) activities proved that extract of ‘Pusa Tarak’ can detoxify more radicals than ‘Pusa Vijay’. We conclude that ‘Pusa Tarak’ can upregulate cellular antioxidants and osmoregulation, and quench more radicals compared to ‘Pusa Vijay’. The results will contribute for selection of better Brassica genus to be grown in Al rich acidic soils, and help in designing strategies for crop breeding and cultivation.
Egyptian Journal of Anaesthesia
Journal of Shoulder and Elbow Surgery
Late presentation of lateral condylar fractures of the humerus is not an uncommon problem in chil... more Late presentation of lateral condylar fractures of the humerus is not an uncommon problem in children, and to lesser extent, in adults. The various surgical interventions for repairing the fracture, correcting the deformity, or even performing anterior transposition of the ulnar nerve as a single procedure or in combination, especially in adults, is still a controversial topic, with a paucity of literature regarding this. There is a risk of loss of the available preoperative range of motion, nonunion, and avascular necrosis. In 19 patients with late presentation of lateral humeral condyle fracture, we assessed the results of only corrective osteotomy and internal fixation with lateral incision without anterior transposition of the ulnar nerve with regard to deformity correction, union, and functional results using the Mayo Elbow Performance Score with at least 24 months of follow-up. All patients (14 men, 5 women; average age, 29.1 years) had Milch type 2, 18 patients presented with cubitus valgus deformity, 1 presented with cubitus varus deformity, and 8 patients had tardy ulnar nerve symptoms. Late-presenting lateral condylar fractures could be managed surgically with our procedure alone even if they have a tardy ulnar neuritis, with excellent results in 17 patients and good results in 2 patients. In situ fusion, deformity correction, and internal fixation is a valuable method for the management of late-presenting lateral condylar fractures in adults.
Agricultural and Food Science
The interest in the use of monoterpenes for insect pest and pathogen control originates from the ... more The interest in the use of monoterpenes for insect pest and pathogen control originates from the need for pesticide products with less negative environmental and health impacts than highly effective synthetic pesticides. The expanding literature on the possibility of the use of these monoterpenes is reviewed and focused on the effects of limonene on various bioorganisms. Limonene is used as insecticide to control ectoparasites of pet animals, but it has activity against many insects, mites, and microorganisms. Possible attractive effects of limonene to natural enemies of pests may offer novel applications to use natural compounds for manipulation of beneficial animals in organic agriculture. However, in few cases limonene-treated plants have become attractive to plant damaging insects and phytotoxic effects on cultivated plants have been observed. As a plant-based natural product limonene and other monoterpenes might have use in pest and weed control in organic agriculture after phy...
Molecules (Basel, Switzerland), Jan 25, 2018
Enteric septicemia of catfish, columnaris disease and streptococcosis, caused by , and , respecti... more Enteric septicemia of catfish, columnaris disease and streptococcosis, caused by , and , respectively, are the most common bacterial diseases of economic significance to the pond-raised channel catfish industry. Certain management practices are used by catfish farmers to prevent large financial losses from these diseases such as the use of commercial antibiotics. In order to discover environmentally benign alternatives, using a rapid bioassay, we evaluated a crude extract from the roots of muscadine against these fish pathogenic bacteria and determined that the extract was most active against . Subsequently, several isolated compounds from the root extract were isolated. Among these isolated compounds, (+)-hopeaphenol () and (+)-vitisin A () were found to be the most active (bacteriostatic activity only) against , with 24-h 50% inhibition concentrations of 4.0 ± 0.7 and 7.7 ± 0.6 mg/L, respectively, and minimum inhibitory concentrations of 9.1 ± 0 mg/L for each compound which were a...
Medicinal chemistry research : an international journal for rapid communications on design and mechanisms of action of biologically active agents, 2018
(Schumach.) Milne-Redhead. (Leguminosae) is used for various medicinal purposes in African countr... more (Schumach.) Milne-Redhead. (Leguminosae) is used for various medicinal purposes in African countries. Phytochemical investigation of yielded two compounds newly isolated from natural sources, 2-methoxyclovan-9-ol (), and methyl--3-hydroxylabd-8(17)-en-15-oate (), along with 14 known compounds (-). Compounds and (alepterolic acid) showed potential selectivity towards with IC 7.89 and 3.42 μM, respectively. Compound showed activity towards and Amastigote with IC 3.84 and 7.82 μM, respectively. The structure activity relationship (SAR) of the isolated metabolites suggested that hydroxylation at C-2 enhances the antiprotozoal activity towards in sesquiterpenes and . Similarly hydroxylation at C-3 in labdane diterpenes elevates the antiprotozoal activity towards
Clinical and experimental hepatology, 2018
The study aimed at investigating the hepatic effect of direct acting anti-hepatitis C virus drugs... more The study aimed at investigating the hepatic effect of direct acting anti-hepatitis C virus drugs (DAAs), sofosbuvir (Sof) and daclatasvir (Dac), in thioacetamide (TAA)-induced liver injury in rats. Animals were allocated to 7 groups: a normal control group, a TAA group (receiving TAA 50 mg/kg, i.p. twice weekly), two TAA groups receiving either a low or a high dose of Sof (Sof-L and Sof-H; 41.1 mg/kg and 82.2 mg/kg, respectively), two TAA groups receiving either a low or a high dose of Dac (Dac-L and Dac-H; 6.2 mg/kg and 12.4 mg/kg, respectively), and a TAA group receiving both Sof-L and Dac-L. After 6 weeks, TAA significantly elevated the serum activities of liver enzymes, along with histopathological evidence of liver injury. These findings were associated with a significant increase in a fibrotic marker (tissue inhibitor metalloproteinase-1 - TIMP-1), proinflammatory cytokine (tumor necrosis factor alpha - TNF-α), and oxidative stress parameters (malondialdehyde [MDA] content, a...
Toxicology mechanisms and methods, Jan 8, 2018
Cilostazol and verapamil are widely used cardiovascular drugs, explored a beneficial effect on di... more Cilostazol and verapamil are widely used cardiovascular drugs, explored a beneficial effect on different organs-induced toxicities. We investigated whether the Nrf2 (nuclear erythroid factor 2) and its downstream pathway may be involved in the protective role of these drugs against TAA-induced renal damage. Renal biomarkers (creatinine and urea) and histopathology were observed. Antioxidant and oxidant indicators; superoxide dismutase (SOD), reduced glutathione (GSH), malondialdehyde (MDA), and total nitrite (NO) were also measured. Antioxidant markers like; Nrf2/hemoxegenase-1 (HO-1) and NADPH quinone oxidoreductase -1 (NQO-1) expressions were determined by ELISA and immunohistochemistry. Cilostazol and verapamil pre-treatment improved serum creatinine and urea elevation. Examined drugs have also an ameliorative effect on TAA-induced elevation in MDA and NO activities and antioxidant enzymes; SOD and GSH. Additionally, the pre-treated drugs significantly up-regulated Nrf2/HO-1/NQO-...
American journal of ophthalmology, Jan 8, 2018
To investigate the natural history of Stargardt disease (STGD1) using fixation location and fixat... more To investigate the natural history of Stargardt disease (STGD1) using fixation location and fixation stability. Multicenter, international, prospective cohort study. Fixation testing was performed using the Nidek MP-1 microperimeter as part of the prospective, multicenter, natural history study on the Progression of Stargardt disease (ProgStar). A total of 238 patients with ABCA4-related STGD1 were enrolled at baseline (bilateral enrollment in 86.6%) and underwent repeat testing at months 6 and 12. Outcome measures included the distance of the preferred retinal locus from the fovea (PRL) and the bivariate contour ellipse area (BCEA). After 12 months of follow-up, the change in the eccentricity of the PRL from the anatomic fovea was -0.0014 degrees (95% confidence interval [CI], -0.27 degrees, 0.27 degrees; P = .99). The deterioration in the stability of fixation as expressed by a larger BCEA encompassing 1 standard deviation of all fixation points was 1.21 degrees squared (deg) (95%...
Uploads
Papers by Mohamed Amr Ibrahim