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359 results on '"Al Shehri, A. M."'

14. Bitwise Retransmission Schemes for Resources Constrained Uplink Sensor Networks

Author

Hassanien, Mohamed A. M., Loskot, Pavel, Al-Shehri, Salman M., Numanoglu, Tolga, and Mert, Mehmet

Subjects
Computer Science - Information Theory
Abstract

Novel bitwise retransmission schemes are devised which retransmit only the bits received with small reliability. The retransmissions are used to accumulate the reliabilities of individual bits. Unlike the conventional automatic repeat request (ARQ) schemes, the proposed scheme does not require a checksum for the error detection. The bits to be retransmitted are reported as a combination number, or two synchronized random number generators (RNGs) at the transmitter and receiver are used to greatly compress the feedback message. The bitwise retransmission decisions and/or combining can be performed after the demodulation or after the channel decoding at the receiver. The bit-error rate (BER) expressions are derived for the case of one and two retransmissions, and verified by computer simulations. Assuming three specific retransmission strategies, the scheme parameters are optimized to minimize the overall BER. For the same number of retransmissions and packet length, the proposed schemes always outperform the frequently used stop-and-wait ARQ. The impact of feedback errors is also considered. Finally, practical designs of the bitwise retransmissions for data fusion from sensor nodes in Zigbee, Wifi and Bluetooth networks are presented., Comment: 14 pages, 17 figures, 3 tables

Published
2017

15. Common Metrics for Analyzing, Developing and Managing Telecommunication Networks

Author

Al-Shehri, Salman M., Loskot, Pavel, Numanoglu, Tolga, and Mert, Mehmet

Subjects
Computer Science - Networking and Internet Architecture
Abstract

The metrics play increasingly fundamental role in the design, development, deployment and operation of telecommunication systems. Despite their importance, the studies of metrics are usually limited to a narrow area or a well-defined objective. Our study aims to more broadly survey the metrics that are commonly used for analyzing, developing and managing telecommunication networks in order to facilitate understanding of the current metrics landscape. The metrics are simple abstractions of systems, and they directly influence how the systems are perceived by different stakeholders. However, defining and using metrics for telecommunication systems with ever increasing complexity is a complicated matter which has not been so far systematically and comprehensively considered in the literature. The common metrics sources are identified, and how the metrics are used and selected is discussed. The most commonly used metrics for telecommunication systems are categorized and presented as energy and power metrics, quality-of-service metrics, quality-of-experience metrics, security metrics, and reliability and resilience metrics. Finally, the research directions and recommendations how the metrics can evolve, and be defined and used more effectively are outlined., Comment: 5 figures, 18 tables

Published
2017

17. Presence of short and cyclic peptides in Acacia and Ziziphus honeys may potentiate their medicinal values

Author

ALaerjani Wed Mohammed Ali, Abu-Melha Saraa Abdullah, Khan Khalid Ali, Ghramh Hamed A., Alalmie Ali Yahya A., Alshareef Rahaf Mohammed Hussein, AL-Shehri Badria M., and Mohammed Mohammed Elimam Ahamed

Subjects
bioactive peptides, lc-ms, pubchem, chemspider, molbase, Chemistry, QD1-999
Abstract

Acacia honey is characterized by high nutritional, antioxidant, antibacterial and immuno-modulatory values. This work investigated the presence of short and cyclic peptides in Acacia and Ziziphus honey samples. Acacia honey samples (Acacia tortilis and Acacia hamulosa) and three Ziziphus honeys (Ziziphus spina-christi) were screened for their short and cyclic peptide contents using the LC-MS and the chemical structure databases. Moreover, the total protein content was determined using the Bradford method. The A. tortilis honey contained three short peptides; HWCC, DSST, and ECH, and the A. hamulosa honey sample contained five short peptides and one cyclic peptide. The short peptides of the A. hamulosa honey were Ac-GMGHG-OH (Ac-MGGHG-OH), Boc-R(Aloc)2-C(Pal)-OH, H-C (1)-NEt2·H-C (1)-NEt2, APAP (AAPP), and GAFQ (deamino-2-pyrid-4-yl-glycyl-dl-alanyl-dl-norvalyl-dl-asparagine). The cyclic peptide of the A. hamulosa honey was cyclo[Aad-RGD-d-F] (cyclo[Aad-Arg-Gly-Asp-d-Phe]). The Ziziphus honey was characterized by the presence of either Almiramide B or Auristatin-6-AQ. A. tortilis, A. hamulosa, and Ziziphus honeys are characterized by the presence of short and cyclic peptides which may contribute to their medicinal values.

Published
2021
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37. Home versus Clinic Blood Pressure Monitoring: Evaluating Applicability in Hypertension Management via Telemedicine

Author

Al-Anazi, Ali F., primary, Gul, Rahim, additional, Al-Harbi, Fahad T., additional, Al-Radhi, Sulaiman A., additional, Al-Harbi, Hamood, additional, Altaher, Altigani, additional, Al-Harbi, Mohammed M., additional, Al-Rashidi, Fahad O., additional, Al-Haweeri, Omer S., additional, Al-Mutairi, Fakhri M., additional, Al-Riyaee, Afyaa A., additional, Al-Hotan, Fai M., additional, Al-Radhi, Alulu A., additional, Al Shehri, Hamdan M., additional, Alharbi, Mohammed S., additional, and ALGhasab, Naif Saad, additional

Published
2023
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40. Positional Isomeric Effects on the Physicochemical Properties of Polymeric Matrix and Polymer@TiO 2 Nanocomposites.

Author

Al-Shehri, Badria M., Bekhoukh, Amina, Benkhatou, Soumia, Moulefera, Imane, Khormi, Afaf Y., Hakami, Rabab A., Alelyani, Magbool, Abdelkader, Jinan, Benyoucef, Abdelghani, and Bakkour, Youssef

Subjects
TRANSMISSION electron microscopy, NANOCOMPOSITE materials, FOURIER transform infrared spectroscopy, ELECTRIC conductivity, ULTRAVIOLET-visible spectroscopy
Abstract

This study investigates the influence of positional isomerism on the physicochemical characteristics of polymeric matrices by examining polyo-anisidine (POA) and polyp-anisidine (PPA) in conjunction with TiO2 nanoparticles. The synthesis of POA@TiO2 and PPA@TiO2 involved chemical oxidative polymerization. X-ray diffraction analysis revealed the anatase structure of TiO2 nanoparticles. Transmission electron microscopy confirmed the successful integration of TiO2 nanoparticles within the polymer matrix. Moreover, FTIR and UV–Vis spectroscopy confirmed the effective interaction between the nanoparticle and the polymer. TGA indicated that POA@TiO2 exhibited a lower weight loss than PPA@TiO2, suggesting an enhancement in thermal stability. Although the incorporation of TiO2 nanoparticles led to a reduction in the electrical conductivity of the pristine polymers (PPA and POA), the resultant nanocomposites retained high conductivities within the range of 0.08 to 0.34 S.cm−1. Furthermore, the POA-based polymer matrix displayed promising electrochemical properties. Significantly, the adherence of the POA layer to TiO2 nanoparticles suggests potential practical applications. [ABSTRACT FROM AUTHOR]

Published
2024
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43. CI-452769-2 PERFORMANCE OF LEADLESS PACEMAKERS IN EXTENDED FOLLOW-UP: 5 YEAR RESULTS FROM THE MICRA VR TRANSCATHETER PACING SYSTEM POST-APPROVAL REGISTRY

Author

El-Chami, Mikhael F., primary, Garweg, Christophe, additional, CLEMENTY, NICOLAS, additional, Al-Smadi Al-Shehri, Faisal M., additional, Iacopino, Saverio, additional, Martinez Sande, Jose Luis, additional, Roberts, Paul R., additional, Tondo, Claudio, additional, Johansen, Jens B., additional, Vinolas, xavier, additional, Cha, Yong-Mei, additional, Grubman, Eric M., additional, BORDACHAR, Pierre, additional, Wallace, Kristie, additional, Fagan, Dedra H., additional, Roys, Amy, additional, and Piccini, Jonathan P., additional

Published
2023
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44. Preparation for disaster management in Saudi Arabia

Author

Al Shehri, M. M.

Subjects
361
Abstract

The incidence and prevalence and the nature of disasters experienced in Arab countries (natural or man-made) requires each country to consider a comprehensive disaster preparedness programme based upon warning systems, inter-sectoral co-ordination, institutions, training programmes and shelter projects. In Saudi Arabia the present health care system has grown out of a few small clinics which were established in the Makkah area which then, after 1951, with the creation of the Ministry of Health, developed into a comprehensive system of health care. In addition to the MoH, eleven other independent health agencies provide health care to their respective populations. Each agency has its own budget, recruits its own personnel and is responsible for running its own health care delivery system. Additionally there is a private sector which is also given financial assistance by the government. Considerable progress has been made in the field of general health but, as yet little has been done to prepare for disasters or other unexpected events, despite several attempts by the government to initiate such action. These attempts have ended up as a series of plans and resolutions which consider modern warning systems, trained disaster manpower, better casualty management, good accommodation and underground hospitals and clinics. However, these plans do not seem to have moved beyond the drawing board. The research highlighted the fact that whilst the Saudi health system is well geared to normal definitions of health care, it is poorly oriented towards the unexpected. There is a lack of clarity of role at the centre of the organisation and, as the research shows, those who would be centrally involved in the management of any disaster do not appear to have any common grasp of what sort of systems exist. There was also found, within this group, a consistent view that disaster planning was a waste of time.

Published
1995

47. An ecophysiological study on the moss Hydrogoniuh fontanum from the Asir Mountains, Saudi Arabia

Author

Al-Shehri, Abdulrahman M.

Subjects
577, Ecology
Abstract

The thesis describes a study on the ecophysiology of the moss Hydrogonium fontanum (C. Mail.) Jaeg., the dominant plant at a waterfall in Saudi Arabia. The influence of environmental variables and water stress on the growth, stress metabolite accumulation and phosphatase activities of the moss was studied in laboratory axenic culture along with observations and experiments conducted in the field. The variables chosen for growth experiments were light flux, flooding, nutrient concentrations and water stress. For phosphatase activities, the influence of temperature, pH, ions, water stress were studied. Differences were found in phosphatase activities for rhlzoids, protonema and leafy shoots of the moss and, therefore, the phosphomonoesterase (PMEase) and phosphodiesterase (PDEase) activities of these fractions were also investigated. H. fontanum was originally collected from the tufa-depositing waterfall (Water chemistry - 44 mg 1(^-1) Na, 44 mg 1(^-1) Ca). High Na and Ca had significant positive effect on yield of the protonema under the laboratory conditions. Low light intensity (10 µmol photon m(^-2) s(^-1)) decreased the yield, but high light intensity (90 µmol photon m(^-2) s(^-1)) increased the yield of the protonema. The moss showed no response to water stress in respect to praline accumulation. Protein content decreased significantly over 48 h with increase in water stress. The Influence of water stress was greater in terms of dry weight and chlorophyll content changes in protonema than in leafy shoots. The protonema was capable of using various organic P substrates as sources of phosphorus and showed both PMEase and PDEase activities. PMEase and PDEase activities were detectable in all moss fractions (rhizoids, protonema, leafy shoots). Laboratory grown material showed higher activities than field grown material. Rhizoids produced the highest PMEase and PDEase activities among the moss fractions. Some leafy shoots collected from the field had low phosphorus content with high phosphatase activities, while others had high phosphorus content with low phosphatase activities. Changes in phosphatase activities in batch culture were studied in relation to growth rate. PMEase activity was first evident when cellular P was 1.15% with low activity (0.117 µmol pNP mg d. wt(^-1) h(^-1)) and PDEase appeared 4 days later when cellular P was 0.54%. The activities increased up to day 12 after which the activities maintained this level. The optimum temperatures, measured over a period of 1 h, for PMEase and PDEase activities were 60 ºC and 65 ºC with pH optima of 5.5-6.0 and 6.4-6.8, respectively. Of the six ions tested, Ca, Zn and P had significant inhibitory effects on the activities at the highest concentration used (10 mM).Drying the moss decreases PMEase and PDEase activities by about 23% and 21% (5-d) and 3.7 and 2,8 times (3 months), respectively. Water stress (PEG treatment) also reduced significantly the activities of PMEase and PDEase with a greater effect on the activity of the latter. A brief comparison in PMEase activity using two different substrates p- nitrophenyl phosphate (pNPP) and 4-methylumbelliferyl phosphate (4-MUP) was made to investigate the pH optima and time course. PMEase activity measured using 250 µM 4-MUP was about 60% of that measured using the same concentration of pNPP.

Published
1992

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