Khalid Ibrahim - Academia.edu (original) (raw)

Papers by Khalid Ibrahim

Applied Computational Electromagnetics Society

This paper presents the design and analysis of a diplexer for satellite communication system base... more This paper presents the design and analysis of a diplexer for satellite communication system based on hybrid spoof surface plasmon polariton (SSPP) and substrate integrated waveguide (SIW) transmission lines. The proposed diplexer consists of a SSPP printed line composed of H-shaped periodical grooved strips to operate as a low pass filter and a SIW to operate as a high pass filter. The operating frequency bands of the proposed diplexer are from 11.7 to 12.75 GHz for the downlink (DL) band, and from 17.3 to 18.35 GHz for the uplink (UL) band. These frequency bands correspond to the operating frequencies in Nile Sat 201 system. The frequencies of the DL and UL bands are adjusted independently by tuning the structure parameters of SSPP and SIW sections, respectively. The proposed hybrid SSPP-SIW diplexer is fabricated and measured. Simulated and measured results show good channel isolation, low return loss and low insertion loss in the required frequency bands.

Annals of Medicine and Surgery

Journal of cardiovascular pharmacology and therapeutics, 2018

Oxidative stress and inflammation are associated with endothelial injury and coronary artery dise... more Oxidative stress and inflammation are associated with endothelial injury and coronary artery disease. Inflammatory factors that promote oxidative damage include endothelin-1 (ET-1), myeloperoxidase (MPO), and C-reactive protein (CRP). Current guidelines recommend the use of statins in patients with risk of atherosclerotic cardiovascular disease (ASCVD). To assess the impact of atorvastatin on plasma inflammatory and oxidant biomarkers in patients with moderate to very high risk of ASCVD. Two hundred ten patients presented to the cardiology clinic were included and stratified into low, moderate, high, and very high risk of ASCVD. Moderate- (20 mg/d) to high-intensity (40 mg/d) atorvastatin was prescribed. Plasma levels of lipids, ET-1, CRP, MPO, total nitrite, lipid peroxides (thiobarbituric acid reactive substances [TBARS]), and superoxide dismutase (SOD) activities were measured at baseline and 12 weeks after treatment. Relative to low-risk patients, baseline plasma inflammatory ma...

Oman medical journal, 2018

Idiopathic (Bell's) palsy is the commonest cause of unilateral facial paralysis in children. ... more Idiopathic (Bell's) palsy is the commonest cause of unilateral facial paralysis in children. Although being idiopathic by definition, possible infectious, inflammatory, and ischemic triggers have been suggested. Bell's palsy is thought to be responsible for up to three-fourths of cases of acute unilateral facial paralysis worldwide. The diagnosis has to be reached after other causes of acute peripheral palsy have been excluded. However, it is rarely described in neonates and young infants. Steroids may have some role in treatment, but antiviral therapies have doubtful evidence of benefit. Prognosis is good, though residual dysfunction is occasionally encountered. We report the case of a two-week-old neonate with no prior illnesses who presented with acute left facial palsy. Clinical findings and normal brain imaging were consistent with the diagnosis of Bell's palsy. The patient had a good response to oral steroids.

Fast digital frequency meter. KM Ibrahim, AS Jaafar, M Abdul-Karim International Journal of Elect... more Fast digital frequency meter. KM Ibrahim, AS Jaafar, M Abdul-Karim International Journal of Electronics 59:22, 193-197, 1985. A simple digital technique is described for the measurement of low frequencies within two cycles of the input wave using a modified dual-slope method. ...

Ieee Transactions on Instrumentation and Measurement, Sep 1, 1987

A novel digital phase meter. KM Ibrahim, M Abdul-Karim IEEE. TRANS. INSTRUM. MEAS. 36:33, 711-716... more A novel digital phase meter. KM Ibrahim, M Abdul-Karim IEEE. TRANS. INSTRUM. MEAS. 36:33, 711-716, 1987. This paper describes a simple digital phase meter using the dual-slope principle. It gives a digital output number ...

Objective To determine whether abnormal EEG and neuroimaging are to be considered as valuable pre... more Objective To determine whether abnormal EEG and neuroimaging are to be considered as valuable predictors for intractable epilepsy and to identify such electroencephalographic and radiological abnormalities associated with medical intractability in children with epilepsy. Methods All children who had a diagnosis of epilepsy in Hamad general hospital before age 5 years from January 2012 till December 2013 were studied; their EEG and neuroimaging results were evaluated and assessed in regard to their long-term epilepsy control. Results Around 90% of children fulfilling diagnosis of intractable epilepsy were below 3 years of age. Male to female ratio was 2:3. 67% of patients cohort had initial abnormal neuro-imaging. More than 70% had abnormal EEG at begining of their illness. Conclusion Early observation and looking for the risk factors for intractable epilepsy may decrease the cost for health care utilization. Medical intractability in childhood epilepsy can be predicted by monitoring...

International Journal of Information Technology and Computer Science, 2013

The hybrid architecture of Terrestrial and Satellite networks discussed in this paper utilizes fr... more The hybrid architecture of Terrestrial and Satellite networks discussed in this paper utilizes frequency reuse. However, at the same time the frequency reuse results in Co-Channel Interference (CCI). The CCI is caused by the mobile users to the satellite end because of the strong receiver on the satellite end. Mainly, this paper will focus on to tone down the CCI and would also show that how the OFDM based adaptive beamforming can be employed to mit igate this interference. The technique which is being used to mitigate this interference is Pre-FFT adaptive beamforming also called as time do main beamforming. In this paper, main task is to mitigate the CCI wh ich is induced by the mobile users to the satellite end and will be considered that there are J users. Out of these J users there is one desired user and rest are interferers. When the interfered data is received at the satellite end, the Pre-FFT adaptive beamforming extracts the desired user data from the interferers by applying the complex weights to the received symbol. The weight for the next symbol is then updated by Least Mean Square (LM S) algorith m and then is applied to it. This process is carried out till all the desired user data is extracted from the interference signal.

The Journal of Pediatrics, 2010

To compare the efficacy and safety of 5%, 3%, and 0.9% saline solution for treating acute bronchi... more To compare the efficacy and safety of 5%, 3%, and 0.9% saline solution for treating acute bronchiolitis in the prehospital setting. This was a double-blind trial including consecutive infants aged <18 months treated in an urban urgent care setting. A total of 165 patients were randomized to receive nebulized 5%, 3%, or 0.9% (normal) saline with epinephrine every 4 hours. The primary efficacy outcome was bronchiolitis severity score improvement at 48 hours (chi2 analysis). Scores and oxygen saturation immediately before and after each treatment were recorded to assess safety. A total of 187 previously healthy infants (median age, 3.1 months) diagnosed with bronchiolitis were enrolled. Positivity for respiratory syncytial virus was similar in the 3 treatment groups (mean, 56%). At 48 hours, the mean severity score for the 5% saline group was 3.69+/-1.09, and that for the 0.9% saline group was 4.12+/-1.11 (P=.04; difference, 0.43, 95% confidence interval for the difference, 0.02-0.88). The mean severity score for the 3% saline group was intermediate at 4.00+/-1.22. Revisit rates after discharge were similar in the 3 treatment groups. No adverse reactions or other safety concerns were identified. Nebulization with 5% hypertonic saline is safe, can be widely generalizable, and may be superior to current treatment for early outpatient treatment of bronchiolitis.

Journal of Applied Polymer Science, 2010

Phenolic compounds are one of the most representative pollutants in industrial wastewater, and ef... more Phenolic compounds are one of the most representative pollutants in industrial wastewater, and efficient removals of them have attracted significant concerns. In this study, several commercial and new synthetic polymers (acrylonitrile, 1,3-butadiene, and styrene copolymer (ABS), styrene, acrylonitrile copolymer (SAN), poly(vinyl chloride) (PVC), poly(methyl methacrylate) (PMMA), poly(tert-butyl acrylate) (ptBA)) with special functionalities were evaluated for their ability to remove phenol from an aqueous solution. Equilibrium studies were conducted in the range of 20-100 mg/L initial phenol concentrations, 3-11 pH solutions, and a temperature range of 25-65 C. The results showed that (styrene, 1,3-butadiene) copolymer (SAN) gave the best adsorption capacity among all of the polymers tested. The solution temperature, phenol concentration, and agitation rate played a significant role in influencing the capacity of the adsorbents toward phenol molecules. An increase in solution temperature led to a significant increase in the adsorption capacity of SAN. The percentage of adsorption decreased when initial concentration of phenol increased. However, the percentage removal of phenol was observed to increase with agitation. Removal of phenol using polymeric microbeads is difficult to investigate under high and low pH values because it requires a lot of acid or base to adjust the pH values in the adsorption media. V

European Polymer Journal, 2004

Four tetradentate nitrogen ligands, viz. dichloro{[N; N 0-diphenyl-N ; N 0-di(quinoline-2-methyl)... more Four tetradentate nitrogen ligands, viz. dichloro{[N; N 0-diphenyl-N ; N 0-di(quinoline-2-methyl)]-1,2-ethylene dia-mine} (1), {[N; N 0-dioctyl-N; N 0-di(quinoline-2-methyl)]-1,2-ethylene diamine} (2), {[N ; N 0-dibenzyl-N; N 0-di(quinoline-2-methyl)]-1,2-ethylene diamine} (3), and (1R,2R)-())-N ; N 0-di(quinoline-2-methyl) di-iminocyclohexane (4), were investigated as novel complexing ligands in iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate where ethyl-2-bromoisobutyrate was the initiator in o-xylene at 90°C. With ligands 1 and 2 the experimental molecular weights increased gradually with monomer conversion. High to moderate conversions (87%, 43%) were obtained in relatively short times (90 min for 1 and 30 min for 2), which indicates an efficient catalyst system, but after these times a dramatic increase in viscosity of the polymerization medium led to loss of control. It is noteworthy that polymerization proceeded in a controlled manner with ligand 1, which has two rather bulky substituents on the Natom. Such bulky ligands did not work for a copper-based system, where they led to excessive terminations or other side reactions. When the bulkiness of the substituents was significantly increased, as in ligand 3, a decrease in polymerization rate and loss of control occurred. Ligand 4 was less efficient than the other ligands, probably because the ethylene bridge was replaced by cyclohexane bridge.

Environmental Pollution, 2011

Date palm (Phoenix dactylifera L.) leaves can be used as an inexpensive biomonitor of the deposit... more Date palm (Phoenix dactylifera L.) leaves can be used as an inexpensive biomonitor of the deposition, accumulation and distribution of heavy metal contamination in arid environments.

BMC Infectious Diseases, 2011

Background: Reports of the etiology of bacteremia in children from Nigeria are sparse and have be... more Background: Reports of the etiology of bacteremia in children from Nigeria are sparse and have been confounded by wide spread non-prescription antibiotic use and suboptimal laboratory culture techniques. We aimed to determine causative agents and underlying predisposing conditions of bacteremia in Nigerian children using data arising during the introduction of an automated blood culture system accessed by 7 hospitals and clinics in the Abuja area. Methods: Between September 2008 and November 2009, we enrolled children with clinically suspected bacteremia at rural and urban clinical facilities in Abuja or within the Federal Capital Territory of Nigeria. Blood was cultured using an automated system with antibiotic removing device. We documented clinical features in all children and tested for prior antibiotic use in a random sample of sera from children from each site. Results: 969 children aged 2 months-5 years were evaluated. Mean age was 21 ± 15.2 months. All children were not systematically screened but there were 59 (6%) children with established diagnosis of sickle cell disease and 42 (4.3%) with HIV infection. Overall, 212 (20.7%) had a positive blood culture but in only 105 (10.8%) were these considered to be clinically significant. Three agents, Staphylococcus aureus (20.9%), Salmonella typhi (20.9%) and Acinetobacter (12.3%) accounted for over half of the positive cultures. Streptococcus pneumoniae and non-typhi Salmonellae each accounted for 7.6%. Although not the leading cause of bacteremia, Streptococcus pneumoniae was the single leading cause of all deaths that occurred during hospitalization and after hospital discharge. Conclusion: S. typhi is a significant cause of vaccine-preventable morbidity while S. pneumoniae may be a leading cause of mortality in this setting. This observation contrasts with reports from most other African countries where non-typhi Salmonellae are predominant in young children. Expanded surveillance is required to confirm the preliminary observations from this pilot study to inform implementation of appropriate public health control measures.

Applied Computational Electromagnetics Society

This paper presents the design and analysis of a diplexer for satellite communication system base... more This paper presents the design and analysis of a diplexer for satellite communication system based on hybrid spoof surface plasmon polariton (SSPP) and substrate integrated waveguide (SIW) transmission lines. The proposed diplexer consists of a SSPP printed line composed of H-shaped periodical grooved strips to operate as a low pass filter and a SIW to operate as a high pass filter. The operating frequency bands of the proposed diplexer are from 11.7 to 12.75 GHz for the downlink (DL) band, and from 17.3 to 18.35 GHz for the uplink (UL) band. These frequency bands correspond to the operating frequencies in Nile Sat 201 system. The frequencies of the DL and UL bands are adjusted independently by tuning the structure parameters of SSPP and SIW sections, respectively. The proposed hybrid SSPP-SIW diplexer is fabricated and measured. Simulated and measured results show good channel isolation, low return loss and low insertion loss in the required frequency bands.

Annals of Medicine and Surgery

Journal of cardiovascular pharmacology and therapeutics, 2018

Oxidative stress and inflammation are associated with endothelial injury and coronary artery dise... more Oxidative stress and inflammation are associated with endothelial injury and coronary artery disease. Inflammatory factors that promote oxidative damage include endothelin-1 (ET-1), myeloperoxidase (MPO), and C-reactive protein (CRP). Current guidelines recommend the use of statins in patients with risk of atherosclerotic cardiovascular disease (ASCVD). To assess the impact of atorvastatin on plasma inflammatory and oxidant biomarkers in patients with moderate to very high risk of ASCVD. Two hundred ten patients presented to the cardiology clinic were included and stratified into low, moderate, high, and very high risk of ASCVD. Moderate- (20 mg/d) to high-intensity (40 mg/d) atorvastatin was prescribed. Plasma levels of lipids, ET-1, CRP, MPO, total nitrite, lipid peroxides (thiobarbituric acid reactive substances [TBARS]), and superoxide dismutase (SOD) activities were measured at baseline and 12 weeks after treatment. Relative to low-risk patients, baseline plasma inflammatory ma...

Oman medical journal, 2018

Idiopathic (Bell's) palsy is the commonest cause of unilateral facial paralysis in children. ... more Idiopathic (Bell's) palsy is the commonest cause of unilateral facial paralysis in children. Although being idiopathic by definition, possible infectious, inflammatory, and ischemic triggers have been suggested. Bell's palsy is thought to be responsible for up to three-fourths of cases of acute unilateral facial paralysis worldwide. The diagnosis has to be reached after other causes of acute peripheral palsy have been excluded. However, it is rarely described in neonates and young infants. Steroids may have some role in treatment, but antiviral therapies have doubtful evidence of benefit. Prognosis is good, though residual dysfunction is occasionally encountered. We report the case of a two-week-old neonate with no prior illnesses who presented with acute left facial palsy. Clinical findings and normal brain imaging were consistent with the diagnosis of Bell's palsy. The patient had a good response to oral steroids.

Fast digital frequency meter. KM Ibrahim, AS Jaafar, M Abdul-Karim International Journal of Elect... more Fast digital frequency meter. KM Ibrahim, AS Jaafar, M Abdul-Karim International Journal of Electronics 59:22, 193-197, 1985. A simple digital technique is described for the measurement of low frequencies within two cycles of the input wave using a modified dual-slope method. ...

Ieee Transactions on Instrumentation and Measurement, Sep 1, 1987

A novel digital phase meter. KM Ibrahim, M Abdul-Karim IEEE. TRANS. INSTRUM. MEAS. 36:33, 711-716... more A novel digital phase meter. KM Ibrahim, M Abdul-Karim IEEE. TRANS. INSTRUM. MEAS. 36:33, 711-716, 1987. This paper describes a simple digital phase meter using the dual-slope principle. It gives a digital output number ...

Objective To determine whether abnormal EEG and neuroimaging are to be considered as valuable pre... more Objective To determine whether abnormal EEG and neuroimaging are to be considered as valuable predictors for intractable epilepsy and to identify such electroencephalographic and radiological abnormalities associated with medical intractability in children with epilepsy. Methods All children who had a diagnosis of epilepsy in Hamad general hospital before age 5 years from January 2012 till December 2013 were studied; their EEG and neuroimaging results were evaluated and assessed in regard to their long-term epilepsy control. Results Around 90% of children fulfilling diagnosis of intractable epilepsy were below 3 years of age. Male to female ratio was 2:3. 67% of patients cohort had initial abnormal neuro-imaging. More than 70% had abnormal EEG at begining of their illness. Conclusion Early observation and looking for the risk factors for intractable epilepsy may decrease the cost for health care utilization. Medical intractability in childhood epilepsy can be predicted by monitoring...

International Journal of Information Technology and Computer Science, 2013

The hybrid architecture of Terrestrial and Satellite networks discussed in this paper utilizes fr... more The hybrid architecture of Terrestrial and Satellite networks discussed in this paper utilizes frequency reuse. However, at the same time the frequency reuse results in Co-Channel Interference (CCI). The CCI is caused by the mobile users to the satellite end because of the strong receiver on the satellite end. Mainly, this paper will focus on to tone down the CCI and would also show that how the OFDM based adaptive beamforming can be employed to mit igate this interference. The technique which is being used to mitigate this interference is Pre-FFT adaptive beamforming also called as time do main beamforming. In this paper, main task is to mitigate the CCI wh ich is induced by the mobile users to the satellite end and will be considered that there are J users. Out of these J users there is one desired user and rest are interferers. When the interfered data is received at the satellite end, the Pre-FFT adaptive beamforming extracts the desired user data from the interferers by applying the complex weights to the received symbol. The weight for the next symbol is then updated by Least Mean Square (LM S) algorith m and then is applied to it. This process is carried out till all the desired user data is extracted from the interference signal.

The Journal of Pediatrics, 2010

To compare the efficacy and safety of 5%, 3%, and 0.9% saline solution for treating acute bronchi... more To compare the efficacy and safety of 5%, 3%, and 0.9% saline solution for treating acute bronchiolitis in the prehospital setting. This was a double-blind trial including consecutive infants aged <18 months treated in an urban urgent care setting. A total of 165 patients were randomized to receive nebulized 5%, 3%, or 0.9% (normal) saline with epinephrine every 4 hours. The primary efficacy outcome was bronchiolitis severity score improvement at 48 hours (chi2 analysis). Scores and oxygen saturation immediately before and after each treatment were recorded to assess safety. A total of 187 previously healthy infants (median age, 3.1 months) diagnosed with bronchiolitis were enrolled. Positivity for respiratory syncytial virus was similar in the 3 treatment groups (mean, 56%). At 48 hours, the mean severity score for the 5% saline group was 3.69+/-1.09, and that for the 0.9% saline group was 4.12+/-1.11 (P=.04; difference, 0.43, 95% confidence interval for the difference, 0.02-0.88). The mean severity score for the 3% saline group was intermediate at 4.00+/-1.22. Revisit rates after discharge were similar in the 3 treatment groups. No adverse reactions or other safety concerns were identified. Nebulization with 5% hypertonic saline is safe, can be widely generalizable, and may be superior to current treatment for early outpatient treatment of bronchiolitis.

Journal of Applied Polymer Science, 2010

Phenolic compounds are one of the most representative pollutants in industrial wastewater, and ef... more Phenolic compounds are one of the most representative pollutants in industrial wastewater, and efficient removals of them have attracted significant concerns. In this study, several commercial and new synthetic polymers (acrylonitrile, 1,3-butadiene, and styrene copolymer (ABS), styrene, acrylonitrile copolymer (SAN), poly(vinyl chloride) (PVC), poly(methyl methacrylate) (PMMA), poly(tert-butyl acrylate) (ptBA)) with special functionalities were evaluated for their ability to remove phenol from an aqueous solution. Equilibrium studies were conducted in the range of 20-100 mg/L initial phenol concentrations, 3-11 pH solutions, and a temperature range of 25-65 C. The results showed that (styrene, 1,3-butadiene) copolymer (SAN) gave the best adsorption capacity among all of the polymers tested. The solution temperature, phenol concentration, and agitation rate played a significant role in influencing the capacity of the adsorbents toward phenol molecules. An increase in solution temperature led to a significant increase in the adsorption capacity of SAN. The percentage of adsorption decreased when initial concentration of phenol increased. However, the percentage removal of phenol was observed to increase with agitation. Removal of phenol using polymeric microbeads is difficult to investigate under high and low pH values because it requires a lot of acid or base to adjust the pH values in the adsorption media. V

European Polymer Journal, 2004

Four tetradentate nitrogen ligands, viz. dichloro{[N; N 0-diphenyl-N ; N 0-di(quinoline-2-methyl)... more Four tetradentate nitrogen ligands, viz. dichloro{[N; N 0-diphenyl-N ; N 0-di(quinoline-2-methyl)]-1,2-ethylene dia-mine} (1), {[N; N 0-dioctyl-N; N 0-di(quinoline-2-methyl)]-1,2-ethylene diamine} (2), {[N ; N 0-dibenzyl-N; N 0-di(quinoline-2-methyl)]-1,2-ethylene diamine} (3), and (1R,2R)-())-N ; N 0-di(quinoline-2-methyl) di-iminocyclohexane (4), were investigated as novel complexing ligands in iron-mediated atom transfer radical polymerization (ATRP) of methyl methacrylate where ethyl-2-bromoisobutyrate was the initiator in o-xylene at 90°C. With ligands 1 and 2 the experimental molecular weights increased gradually with monomer conversion. High to moderate conversions (87%, 43%) were obtained in relatively short times (90 min for 1 and 30 min for 2), which indicates an efficient catalyst system, but after these times a dramatic increase in viscosity of the polymerization medium led to loss of control. It is noteworthy that polymerization proceeded in a controlled manner with ligand 1, which has two rather bulky substituents on the Natom. Such bulky ligands did not work for a copper-based system, where they led to excessive terminations or other side reactions. When the bulkiness of the substituents was significantly increased, as in ligand 3, a decrease in polymerization rate and loss of control occurred. Ligand 4 was less efficient than the other ligands, probably because the ethylene bridge was replaced by cyclohexane bridge.

Environmental Pollution, 2011

Date palm (Phoenix dactylifera L.) leaves can be used as an inexpensive biomonitor of the deposit... more Date palm (Phoenix dactylifera L.) leaves can be used as an inexpensive biomonitor of the deposition, accumulation and distribution of heavy metal contamination in arid environments.

BMC Infectious Diseases, 2011

Background: Reports of the etiology of bacteremia in children from Nigeria are sparse and have be... more Background: Reports of the etiology of bacteremia in children from Nigeria are sparse and have been confounded by wide spread non-prescription antibiotic use and suboptimal laboratory culture techniques. We aimed to determine causative agents and underlying predisposing conditions of bacteremia in Nigerian children using data arising during the introduction of an automated blood culture system accessed by 7 hospitals and clinics in the Abuja area. Methods: Between September 2008 and November 2009, we enrolled children with clinically suspected bacteremia at rural and urban clinical facilities in Abuja or within the Federal Capital Territory of Nigeria. Blood was cultured using an automated system with antibiotic removing device. We documented clinical features in all children and tested for prior antibiotic use in a random sample of sera from children from each site. Results: 969 children aged 2 months-5 years were evaluated. Mean age was 21 ± 15.2 months. All children were not systematically screened but there were 59 (6%) children with established diagnosis of sickle cell disease and 42 (4.3%) with HIV infection. Overall, 212 (20.7%) had a positive blood culture but in only 105 (10.8%) were these considered to be clinically significant. Three agents, Staphylococcus aureus (20.9%), Salmonella typhi (20.9%) and Acinetobacter (12.3%) accounted for over half of the positive cultures. Streptococcus pneumoniae and non-typhi Salmonellae each accounted for 7.6%. Although not the leading cause of bacteremia, Streptococcus pneumoniae was the single leading cause of all deaths that occurred during hospitalization and after hospital discharge. Conclusion: S. typhi is a significant cause of vaccine-preventable morbidity while S. pneumoniae may be a leading cause of mortality in this setting. This observation contrasts with reports from most other African countries where non-typhi Salmonellae are predominant in young children. Expanded surveillance is required to confirm the preliminary observations from this pilot study to inform implementation of appropriate public health control measures.