Abdullah Alshehri - Academia.edu (original) (raw)

Papers by Abdullah Alshehri

2018 25th IEEE International Conference on Electronics, Circuits and Systems (ICECS)

In this paper, we propose a forward body biasing technique to enhance the performance of the Stro... more In this paper, we propose a forward body biasing technique to enhance the performance of the StrongARM comparators. We apply this technique, which is mainly based on clocked tuning of the threshold voltage of the NMOS cross-coupled transistors, to different architectures, namely: Kobayashi, Razavi, and Improved StrongARM comparators. The circuits are simulated in the standard 65nm CMOS technology and performance improvement of up to 20.8% has been achieved while maintaining the same energy loss.

Annals of Dental Specialty, 2021

INTED2019 Proceedings, 2019

I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, inc... more I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. I understand that my thesis may be made electronically available to the public.

The purpose of this thesis is to analyze a non-intrusive connectivity visualization method for OL... more The purpose of this thesis is to analyze a non-intrusive connectivity visualization method for OLSR-based MANET topology in different mobility models. The visualization relies on the local topology databases (neighborhood database and topology database) available in OLSR nodes in the network. Two different views are considered in this method: central view and nodal view. In the central view, the network topology is viewed from a control center which has access to the databases of all nodes, while on the other hand, the nodal visualization provides a picture of the network topology from individual nodes point of view. In this thesis, the full view of the network has been compared to the nodal view to calculate the error rate for topology discovery, based on the total numbers of active and undiscovered links. The main contribution of this thesis is to analyze and improve the accuracy of coarse localization techniques under different mobility models, using the Force-directed algorithm to calculate the approximate location of the nodes. The localization information was gathered from layer-3 connectivity, utilizing anchor nodes that are equipped with GPS and other non-GPS nodes instead of using traditional methods that include received signal strength, time of arrival and angle of arrival. The approximate location information of the nodes derived from this technique has been compared with original node location in order to determine the accuracy of this technique. To improve the accuracy, several mobility prediction filters such as moving average filter, Kalman filter and low pass filter have been applied to the approximate location data. The simulation is done to calculate the error between the original location data and the coarse approximations, and the results shows that Moving Average provides the best results.

International Journal of Machine Learning and Computing, 2020

Identification of individuals based on behavior or biology is known as biometrics. A recent and w... more Identification of individuals based on behavior or biology is known as biometrics. A recent and widely used development in the field of biometrics is iris recognition for identification. The average iris recognition algorithm requires taking an image of the iris, then testing and segmenting the image. This is commonly achieved through both statistical and classical techniques. Every method has strengths and weaknesses. In this proposal, we present a novel iris recognition approach. The objective of our study is to create a technique for accessing computers and computer networks. Due to widespread use of computers in many forms (desktop, handheld, etc.) our technique offers valuable security for information. This wavelet-based algorithm will be capable of enhancing the scanned image, reducing noise, and extracting important elements of the picture to check against data within a database. Additionally, our method may be generalized to a variety of applications including surveillance, e-commerce, ATM transactions, and others.

The Korean Journal of Gastroenterology, 2020

Background/Aims: Limited data is available in Saudi Arabia (SA) regarding the prevalence of funct... more Background/Aims: Limited data is available in Saudi Arabia (SA) regarding the prevalence of functional dyspepsia (FD) symptoms and its subtypes, as defined by the ROME IV criteria. This study evaluated the burden of self-reported FD symptoms in the adult general population of SA and the current clinical practices. Methods: A web-based national cross-sectional health survey of the general population of SA was conducted using the Rome IV Diagnostic Questionnaire for Functional Gastrointestinal Disorders in Adults with additional questions on the presence of symptoms compatible with functional heartburn (FH) and irritable bowel syndrome (IBS). The quality of life and somatization questionnaires were also included. Results: Overall, 3,114 adults completed the questionnaire, but 303 (9.7%) were excluded due to inconsistent responses. Of the 2,811 consistent responders, 532 (18.3%) fulfilled the Rome IV criteria for FD symptoms. These were distributed into the FD subtypes as follows: 208 (7.4%) had postprandial distress syndrome, 228 (8.1%) had epigastric pain syndrome, and 96 (3.4%) had the overlapping variant. IBS-like symptoms were reported in 232 (44%) and FH in 102 (19%) 19% (102) of the subjects with functional dyspepsia. H. pylori-associated dyspepsia was reported by 25% (87/348). High somatization, lower quality of life scores, younger age, and female sex were associated more with the FD symptoms participants than those without. Approximately 1/5 respondents used over-the-counter medications to relieve the FD symptoms. Conclusions: In this population-based survey, FD affected almost 1/5 of the responding adult population in SA, which was less than previously reported.

2017 International Applied Computational Electromagnetics Society Symposium - Italy (ACES), Mar 1, 2017

Different structures of transmission lines were designed and fabricated in standard CMOS technolo... more Different structures of transmission lines were designed and fabricated in standard CMOS technology to estimate some critical parameters including the RMS value of the surface roughness and the loss tangent. The input impedances for frequencies up to 50 GHz were modeled and compared with measurements. The results demonstrated a strong correlation between the used model with the proposed coefficients and the measured results, attesting the robustness of the model and the reliability of the incorporated coefficients values.

Majmaah Journal of Health Sciences, 2020

Background and Aim: Recently bariatric surgeries became trend for obese individuals. As known obe... more Background and Aim: Recently bariatric surgeries became trend for obese individuals. As known obesity is major risk factor for cardiovascular diseases. We aim to describe effect of bariatric surgeries on cardiovascular risk factors including glycemic control, lipid profile, blood pressure, and weight for patients registered at tertiary center in Saudi Arabia. Methods: Retrospective cohort including obese patients who underwent bariatric surgeries at King Abdullah Medical City, Makkah between 2013 and February 2016. Results: Total of 566 patients aged 34.8±10.2 years at time of operation. More than half were females (58.1%). Almost all patients underwent laparoscopic sleeve gastrectomy (95.9%). Diabetes and hypertension were the most prevalent comorbidities (24.8% and 18.9%, respectively). There is significant reduction in mean Body Mass Index from 47.6 kg/m2 to 31.8 kg/m2 and in Glycosylated Hemoglobin from 6.8% to 5.7% at 24 months of follow-up (p

Global Heart, 2020

Background: Familial hypercholesterolemia (FH) is an autosomal dominant inherited genetic disorde... more Background: Familial hypercholesterolemia (FH) is an autosomal dominant inherited genetic disorder and results in the development of coronary artery disease (CAD). Clinical diagnosis of homozygous HH patients is usually straightforward because persistent hypercholesterolemia can produce xanthoma and corneal arcus. However, xanthoma may also be misdiagnosed as skin lesions and could therefore be mistreated. The aim of this case study report is to highlight the plight of patients with FH as means of raising awareness of the condition among dermatologists and health care practitioners, also to determine the genotype-phenotype correlation in severely affected homozygous FH proband patients. Methods: Genetic screening of FH associated genes was performed by Ion Torrent next-generation sequencing and cascade screening by capillary sequencing. Results: We present two clinical cases with prominent skin lesions seen in a dermatology clinic that were referred to plastic surgery for excision. Genetic testing was performed later, and confirmed common single nucleotide deletion variant (c.2027delG) in the LDLR alleles consequent to a frameshift mutation p.(G676Afs*33). In addition to the LDLR variant, two possibly damaging APOB variants p.(L3313I) and p.(L1212M) and three damaging variants p.(R19*), p.(G83Q) and p.(S474*) in APOC3, PON2 and LPL genes respectively were identified. The PON2 gene variant p.(G83Q) was found to be novel, while others have been previously reported. Both patients were refractory to pharmacological therapies and are currently on lipoprotein apheresis (LA). Conclusions: The present report indicates the need for increased awareness of FH, among the public and healthcare practitioners and supports the need for diagnostic screening and cascade genetic testing of this high-risk condition, which could ultimately lead to better prevention of CHD in this lethal condition.

The Open Civil Engineering Journal, 2019

Background:The construction companies need to maintain their success levels to survive in the com... more Background:The construction companies need to maintain their success levels to survive in the competitive business environment. The concept of just-in-time plays a significant role to reduce the costs and fulfill the needs of valued customers.Objective:The study aims to evaluate the role of honest customer services that are provided to the construction companies in Saudi Arabia.Methods:The study has used a case study approach to analyze the role of on-time and honest customer services in the success of small construction companies. Interviews were conducted to gather details and characteristics of the associated company. It mainly focused on the interactions and behaviors of participants, rather than calculations.Results:The results have provided a great understanding of the success of construction companies based on success factors. The organizational culture, delayed schedule, required quantity, and just-in-time purchasing are amongst the exceptional and highly effective factors o...

Saudi Critical Care Journal, 2019

Background: Sepsis is a life-threatening condition existing worldwide and is frequently known as ... more Background: Sepsis is a life-threatening condition existing worldwide and is frequently known as the “hidden killer” because it is a time-sensitive illness, like myocardial infarction and cardiac arrest; therefore, prehospital providers must have adequate knowledge about it. Aim: The aim was to measure the knowledge and perception of sepsis among emergency medical service (EMS) providers to assure better patient prognosis. Methodology: A cross-sectional paper-based questionnaire survey comprising 15 questions, divided into three sections, was conducted at Makkah Saudi Red Crescent Authority to evaluate their knowledge related to the signs and symptoms of sepsis in particular and management and perception of sepsis in general. The responses received were categorized according to the specialties considering P < 0.05 as statistically significant. Results: The total number of study participants was 102; 26 participants were excluded because they did not meet the inclusion criteria. Among the remaining 76 participants, 64.5% were technicians and 35.5% were specialists. The most common age group was 25 ± 5 years which composed 46.1% of the total participants, and the highest years of experience was between 6 and 10 years which composed 47.4% of the total participants. According to a 5-point Likert scale, there was an adequate level of EMS provider perception on the knowledge of sepsis. Nearly 55.6% of the specialists knew the three stages of sepsis better than technicians (40.8%). Both the technicians and specialists had poor knowledge regarding hypothermia (technicians 20.4% and specialists 25.9%) as a sign of sepsis, in addition to administering intravenous antibiotics (technicians 28.6% and specialists 14.8%) as a management modality. On the other hand, both had enough knowledge regarding the other signs and symptoms with an average of 72.8% and the management of sepsis with an average of 72%. Conclusion: Overall, all participants had a good level of knowledge related to sepsis. However, the participants lack knowledge on administering antibiotics and hypothermia; moreover, their attitude and willingness toward recognizing and managing septic patients is unknown. Hence, it is recommended that further research may be undertaken to measure it at a larger scale and efforts be made to educate the providers certainly on the knowledge they lack of.

Electrochimica Acta, 2018

Morphology and stress evolution during the initial stages of intergranular Morphology and stress ... more Morphology and stress evolution during the initial stages of intergranular Morphology and stress evolution during the initial stages of intergranular corrosion of X70 steel corrosion of X70 steel

Objectives: Evaluate and assess the effect of an innovative double layer, single application dese... more Objectives: Evaluate and assess the effect of an innovative double layer, single application desensitizing/whitening technique on Nitrate penetration and total color change. Methods: Specimens were prepared from extracted caries free human molars (n=160). Teeth were randomly assigned into four groups: 100μl 25% hydrogen peroxide "Philips Zoom chairside" as control group (CTRL), double layer treatment of 20μl 5% potassium nitrate " Relief ACP, Philips oral care" and 100μl 25% hydrogen peroxide (DL20), double layer treatment of 40μl 5% potassium nitrate and 100μl 25% hydrogen peroxide (DL40), and one layer treatment of 40 μl 5% potassium nitrate (PN40). Spectrophotometric color measurements (Vita EasyShade) were done at base line (T0), one day (T1), and one month (T2) following the treatment. Nitrate penetration was measured using a nitrate/nitrite assay kit. Group comparisons of tooth color difference measurements, and nitrate penetration readings were made using the Kruskal-Wallis test. Adjustment was made for pairwise treatment comparisons using the Tukey method in conjunction with an overall 0.05 level of significance. Results: 160 teeth were used. Color difference (ΔE) results at (T1) and (T2) showed no significant difference among the CTRL, DL20, DL40 groups. But there was a statistical significant difference between those groups and the single layer (PN40) group (p<0.001, p<0.001 respectively). Data provided strong evidence of differences in nitrate penetration among the four groups (p<0.0001). Groups DL20, DL40, PN40 significantly differed from CTRL, but could not be said to differ from each other. Conclusion: Double layer technique showed no effect on color difference at one day and one month. The application of hydrogen peroxide didn't affect the penetration of potassium nitrate.

KI - Künstliche Intelligenz, 2018

Keyboard typing patterns are a form of behavioural biometric that can be usefully employed for th... more Keyboard typing patterns are a form of behavioural biometric that can be usefully employed for the purpose of user authentication. The technique has been extensively investigated with respect to the typing of fixed texts such as passwords and pin numbers, so-called static authentication. The typical approach is to compare a current "typing sample" with a typing template expressed in terms of a feature vector comprised of keystroke dynamics. The feature vector approach has also been applied in the context of continuous authentication where features are extracted from free typing. However, the use of feature vectors for keystroke continuous authentication entails a number of disadvantages, mostly associated with the size of the feature vectors and their generation, which need to capture a large number of features to be effective; thus making the technique unsuitable for iterative (real-time) authentication as would be required in the case of, for example, online assessments. To address this issue, a mechanism whereby iterative real-time keystroke continuous authentication can be achieved is proposed, by considering typing behaviour as a form of time series, that avoids the disadvantages associated with the feature vector approach. The reported experimental results show a significantly improved performance using the proposed method in comparison with the feature vector based technique.

Journal of electrocardiology

Diastolic dysfunction is the early sign of myocardial ischemia that usually occurs earlier than E... more Diastolic dysfunction is the early sign of myocardial ischemia that usually occurs earlier than ECG changes. To determine the existence of a correlation between ST segment shift and diastolic dysfunction among patients with AMI. Fourty six patients with significant ST segment elevation or depression and having symptoms of acute myocardial infarction for <12 h were enrolled in this study. Patients were examined for serial ECG, cardiac enzymes, and echocardiography. There was no significant correlation between ST segment elevation or depression and majority of the diastolic indices. Few diastolic parameters; such as, E/A ratio of the mitral valve and deceleration time of the tricuspid valve showed a direct correlation with the ECG changes. Whereas, the Tei Index of the LV function showed a borderline correlation to the ST segment elevation at discharge. Overall, there was no correlation between either ST segment elevation or depression and the LV or RV diastolic function in patient...

International journal of surgery case reports, 2018

Osteochondroma, a type of cartilaginous tumour, is the most common benign tumour affecting the bo... more Osteochondroma, a type of cartilaginous tumour, is the most common benign tumour affecting the bone. These tumours usually arise around the knee, proximal humerus, and pelvis, but very rarely occur at the scapula. Osteochondromas are usually asymptomatic and uncomplicated, but must be treated by surgical resection. In this report, we present a rare case of a symptomatic scapular osteochondroma associated with scapular winging in a 30-year-old man. This tumour exhibited positive radiological findings and was treated surgically, leading to a complete resolution of the patient's symptoms with no history of recurrence. This case was unique because although the patient presented in his fourth decade of life, he had not noticed any signs indicative of lesional growth during adolescence and the maturation process. Additionally, this case was symptomatic and involved an unusual site. By reporting this rare case of a ventral-side scapular osteochondroma that presented with scapular wingi...

Scientific reports, Jan 28, 2018

Design of an efficient delivery system is a generally recognised bottleneck in translation of siR... more Design of an efficient delivery system is a generally recognised bottleneck in translation of siRNA technology into clinic. Despite research efforts, cellular processes that determine efficiency of siRNA silencing achieved by different delivery formulations remain unclear. Here, we investigated the mechanism(s) of cellular internalisation of a model siRNA-loaded liposome system in a correlation to the engagement of delivered siRNA with its target and consequent silencing by adopting siRNA molecular beacon technology. Probing of cellular internalisation pathways by a panel of pharmacological inhibitors indicated that clathrin-mediated (dynamin-dependent) endocytosis, macropinocytosis (dynamine independent), and cell membrane cholesterol dependent process(es) (clathrin and caveolea-independent) all play a role in the siRNA-liposomes internalization. The inhibition of either of these entry routes was, in general, mirrored by a reduction in the level of siRNA engagement with its target ...

Proceedings of the Eighth Saudi Students Conference in the UK, 2015