AMA International University Bahrain

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Gonzales T.T.,Nagasaki University | Gonzales T.T.,AMA International University Bahrain | Katoh M.,Seikai National Fisheries Research Institute | Ghaffar M.A.,National University of Malaysia | Ishimatsu A.,Nagasaki University
Journal of Morphology | Year: 2011

To illustrate vascular modification accompanying transition from aquatic to amphibious life in gobies, we investigated the respiratory vasculatures of the gills and the bucco-opercular cavities in one of the most terrestrially-adapted mudskippers, Periophthalmodon schlosseri, using the corrosion casting technique. The vascular system of Pn. schlosseri retains the typical fish configuration with a serial connection of the gills and the systemic circuits, suggesting a lack of separation of O 2-poor systemic venous blood and O 2-rich effluent blood from the air-breathing surfaces. The gills appear to play a limited role in gas exchange, as evidenced from the sparsely-spaced short filaments and the modification of secondary lamellar vasculature into five to eight parallel channels that are larger than red blood cell size, unlike the extensive sinusoidal system seen in purely water-breathing fishes. In contrast, the epithelia of the bucco-opercular chamber, branchial arches, and leading edge of the filaments are extensively laden with capillaries having a short (<10 μm) diffusion distance, which strongly demonstrate the principal respiratory function of these surfaces. These capillaries form spiral coils of three to five turns as they approach the epithelial surface. The respiratory capillaries of the bucco-opercular chamber are supplied by efferent blood from the gills and drained by the systemic venous pathway. We also compared the degree of capillarization in the bucco-opercular epithelia of Pn. schlosseri with that of the three related intertidal-burrowing gobies (aquatic, non-air-breathing Acanthogobius hasta; aquatic, facultative air-breathing Odontamblyopus lacepedii; amphibious air-breathing Periophthalmus modestus) through histological analysis. The comparison revealed a clear trend of wider distribution of denser capillary networks in these epithelia with increasing reliance on air breathing, consistent with the highest aerial respiratory capacity of Pn. schlosseri among the four species. © 2011 Wiley-Liss, Inc.


Ismail A.S.,AMA International University Bahrain | Andeng P.B.,Egyptian Petroleum Research Institute | El-Meligi A.A.,National Research Center of Egypt
Journal of Corrosion Science and Engineering | Year: 2014

The present research work investigated the corrosion behaviour of casted pure aluminium metal and aluminium-copper alloy after running weight loss tests in different concentration ratios of H2SO4 media at RT and 50°C, respectively. Corrosion penetration rate was determined within interval immersion periods of 5 hours. At RT, it was observed that pure aluminium samples have low corrosion resistance in concentrations 10% and 15% of H2SO4 solutions. Moreover, corrosion rate increases slightly with increasing concentration of H2SO4 media and the attack was more significant at 50°C. Al-Cu alloy show decreasing of weight loss and more corrosion resistance in both ratios. The corrosion penetration rate of Al samples increases in the order Al-Cu < Al as a result of the formation of thin protective aluminium-copper oxide films. The visual observations shown that there is a streaking and grooves of both samples correlated directly with the increased exposure period in the acidic medium but in case of Al-Cu alloy there are a several horizontal fine darkened pits grew along the surface. © 2014 University of Manchester and the authors.


Ismail A.S.,AMA International University Bahrain | Ismail A.S.,Egyptian Petroleum Research Institute
Silicon | Year: 2016

The present paper discussed the corrosion behavior of aluminum-silicon-copper-manganese alloy compared with the pure aluminum metal which already reported. Weight loss tests carried out in concentration ratios of H 2SO4 solutions at different temperatures. As a part of the study, corrosion penetration rate determined within interval immersion periods of 5 h. At room temperature, it is observed that aluminum alloys shows decreasing of weight loss and more corrosion resistance in concentrations 10 and 15 % of H 2SO4 solutions compared with the obtained results of pure Al metal. Moreover, corrosion rate increases slightly with increasing concentration of H 2SO4media and the attack is more significant at 50 ∘C. Also, the corrosion penetration rate of Al alloy decreased in the same trend as a result of the formation of thin protective multi oxide films of aluminum, silicon, copper and manganese. Furthermore, the microscopic analysis showed that there is fine pits appeared on the Al alloy surface correlated directly with the increased exposure period in the acidic solution whereas in case of pure Al metal there were a many horizontal streaks formed along the surface. © 2015, Springer Science+Business Media Dordrecht.


Sharef Z.T.,AMA International University Bahrain | Alaradi A.E.,University of Technology Malaysia | Sharef B.T.,National University of Malaysia
Proceedings - 2012 4th International Conference on Computational Intelligence, Communication Systems and Networks, CICSyN 2012 | Year: 2012

In this paper, a detailed link level simulation has been studied and optimized to investigate the physical layer performance of Worldwide Interoperability for Microwave Access (WiMAX) IEEE 802.16e over AWGN and multipath Rayleigh fading channels, in which ITU-Reference channel models have been used. Two 802.16e based OFDMA transceivers have been designed by using MATLAB Simulink, the first one doesn't support channel estimation whereas the second does. Moreover, the effect of fading channel, Doppler shift and cyclic prefix on the system design performance has been analyzed and investigated. The bit error rate (BER) vs. bit energy-to-noise density ratio (Eb/No) curves was used to evaluate and compare the performance of QPSK modulation technique. The outcomes of simulation results clarified how the use of channel estimation improves the system performance, whereas obviously, the investigated system suffers from severe performance degradation and high probability of error whenever channel estimation is not applied. © 2012 IEEE.


Van Zuuren E.J.,Leiden University | Fedorowicz Z.,AMA International University Bahrain | Carter B.,Bangor University
British Journal of Dermatology | Year: 2012

Female pattern hair loss (FPHL) or androgenic alopecia is the most common type of hair loss affecting women with reduced hair density and can have a serious psychological impact. It is characterized by progressive replacement of slow cycling terminal hair follicles by miniaturized, rapidly cycling vellus hair follicles. The frontal hair line may or may not be preserved. The aim of this review was to assess the evidence for the effectiveness and safety of the treatments available for FPHL. Searches included: Cochrane Skin Group Specialised Register, Cochrane Central Register of Controlled Clinical Trials in The Cochrane Library, MEDLINE, EMBASE, AMED, PsycINFO, LILACS and several ongoing trials registries (October 2011). Randomized controlled trials in women with FPHL were identified. Twenty-two trials, comprising 2349 participants, were included. A range of interventions was evaluated, with 10 studies examining varying concentrations of minoxidil. Pooled data from four studies indicated that a greater proportion of participants treated with minoxidil reported a moderate increase in their hair regrowth compared with placebo (relative risk 1·86, 95% confidence interval 1·42-2·43). There was no difference between the number of adverse events experienced in the twice daily minoxidil and the placebo intervention groups, except for a reported increase with minoxidil 5% twice daily. Single studies accounted for most of the other comparisons, which were assessed as either having high risk of bias and/or they did not address the prespecified outcomes for this review and provided limited evidence of either the effectiveness or safety of these interventions. Further well-designed, adequately powered randomized controlled trials investigating other treatment options are still required. © 2012 The Authors. BJD © 2012 British Association of Dermatologists.


Qadami E.,AMA International University Bahrain | Ampoon A.,AMA International University Bahrain | Manansala N.H.,AMA International University Bahrain
Journal of the Bahrain Medical Society | Year: 2013

Background: The prevalence of renal stone disease is increasing, with 5% of women and 12% of men in the US developing a kidney stone during their life. Assessment of prevalence can help provide an improved understanding of risk factors and the impact of the disease at community level in Bahrain. Objective: This study aimed to determine the prevalence of renal calculi and the clinical profile of patients presenting with renal colic at the American Mission Hospital (AMH). Method: Study design, a retrospective medical record review of all patients with renal colic who visited AMH Jan to Dec 2010. Data extraction was carried out by one investigator and cross checked. Results: In this study population the prevalence of renal colic was found to be 0.022%, and of renal calculi 0.020%. A higher percentage (60.5%) of females than males were diagnosed with renal calculi: and 63% occurred in the 20-40 yr and 30% in the higher, and 7% in the lower (<20 yr), age groups. Non-smokers (67.4%) were more affected than smokers. Most (72%) patients had no history of alcohol intake; compared to mild (7%), moderate (19%), and high intake (2%). More cases (72%) of renal calculi were diagnosed in the winter season compared to 28% in the summer season. Conclusion: The majority of patients with renal colic were diagnosed with renal calculi which were more common in females and in the 20-40 yr age group. There appeared to be no significant relationship between smoking and alcohol intake and prevalence of renal calculi.


Fedorowicz Z.,AMA International University Bahrain
Cochrane database of systematic reviews (Online) | Year: 2012

Dysmenorrhoea is a common gynaecological complaint that can affect as many as 50% of premenopausal women, 10% of whom suffer severely enough to be rendered incapacitated for one to three days during each menstrual cycle. Primary dysmenorrhoea is where women suffer from menstrual pain but lack any pathology in their pelvic anatomy. Beta2-adrenoceptor agonists have been used in the treatment of women with primary dysmenorrhoea but their effects are unclear. To determine the effectiveness and safety of beta2-adrenoceptor agonists in the treatment of primary dysmenorrhoea. We searched the Cochrane Menstrual Disorders and Subfertility Group Specialised Register; CENTRAL (The Cochrane Library 2011, Issue 8); MEDLINE; EMBASE; PsycINFO and the EBM Reviews databases. The last search was on 22 August 2011. Randomised controlled trials comparing beta2-adrenoceptor agonists with placebo or no treatment, each other or any other conventional treatment in women of reproductive age with primary dysmenorrhoea. Two review authors independently assessed trial quality and extracted the data. Five trials involving 187 women with an age range of 15 to 40 years were included. Oral isoxsuprine was compared with placebo in two trials; terbutaline oral spray, ritodrine chloride and oral hydroxyphenyl-orciprenalin were compared with placebo in a further three trials. Clinical diversity in the studies in terms of the interventions being evaluated, assessments at different time points and the use of different assessment tools mitigated against pooling of outcome data across studies in order to provide a summary estimate of effect for any of the comparisons. Only one study, with unclear risk of bias, reported pain relief with a combination of isoxsuprine, acetaminophen and caffeine. None of the other studies reported any significant clinical difference in effectiveness between the intervention and placebo. Adverse effects were reported with all of these medications in up to a quarter of the total number of participants. They included nausea, vomiting, dizziness, quivering, tremor and palpitations. The evidence presented in this review was based on a few relatively small-sized studies that were categorised to have unclear to high risk of bias, which does not allow confident decision-making at present about the use of beta2-adrenoceptor agonists for dysmenorrhoea. The benefits as reported in one study should be balanced against the wide array of unacceptable side effects documented with this class of medication. We have emphasised the lack of precision and limitations in the reported data where appropriate.


Fedorowicz Z.,AMA International University Bahrain
Cochrane database of systematic reviews (Online) | Year: 2012

Root canal treatment is carried out on teeth in which irreversible pulpitis has led to necrosis of the dental pulp. As a treatment option it is an alternative to dental extraction. Mechanical preparation and irrigation with antiseptic or antibacterial solutions destroys bacteria and cleans the infected root canal. Irrigants should be effective in deactivating bacteria in the entire root canal space without causing any adverse tissue reactions. Sodium hypochlorite (NaOCl) and chlorhexidine are commonly used but there is uncertainty as to which solution, concentration or combination is the most effective. To assess the effects of irrigants used in the non-surgical root canal treatment of mature permanent teeth. We searched the Cochrane Oral Health Group's Trials Register (to 5 July 2012), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2012, Issue 4), MEDLINE via Ovid (1950 to 5 July 2012), EMBASE via Ovid (1980 to 5 July 2012), LILACS via BIREME (1980 to 5 July 2012). There were no restrictions regarding language or date of publication. Randomised controlled trials in single or multi-rooted permanent teeth with pulpal or periapical pathology or both, which require root canal treatment. Irrigants either against each other or against inactive irrigant or placebo. Combinations of irrigants were allowed and if used in conjunction with EDTA (ethylenediaminetetra-acetic acid) or similar chelating agents. Two review authors independently assessed risk of bias of included trials and extracted data. We included 11 trials involving 851 participants with 879 teeth which had undergone root canal treatment and involved the use of irrigants. Two trials were assessed as being at low risk of bias, with six unclear and three high. Four trials compared sodium hypochlorite versus chlorhexidine, however, no primary outcomes and only one secondary outcome, bacterial growth cultures, was reported for two of these trials (20% and 50% of teeth in the control group had positive bacterial culture). The meta-analysis indicated no strong evidence of a difference in the existence of bacterial growth between the interventions (risk ratio 0.73; 95% confidence interval 0.34 to 1.56; P = 0.41). The seven remaining trials each compared different interventions and only two of these trials included useable data on the primary outcomes of swelling and pain. One trial compared sodium hypochlorite 5.25% alone versus sodium hypochlorite 5.25% combined with hydrogen peroxide 3%, and versus normal saline and reported pain at 3 to 14 days after the procedure. There was no evidence of a difference in pain between the three groups. The other trial compared sodium hypochlorite 5% versus sodium hypochlorite with 'proteolytic enzyme', and there was no evidence of a difference in swelling between the groups. Two further trials reported bacterial growth, and three trials failed to report any data which could be used in the review. None of the included trials reported any data on adverse effects nor radiological changes in periapical radiolucency. Although root canal irrigants such as sodium hypochlorite and chlorhexidine appear to be effective at reducing bacterial cultures when compared to saline, most of the studies included in this review failed to adequately report these clinically important and potentially patient-relevant outcomes. There is currently insufficient reliable evidence showing the superiority of any one individual irrigant. The strength and reliability of the supporting evidence was variable and clinicians should be aware that changes in bacterial counts or pain in the early postoperative period may not be accurate indicators of long-term success. Future trials should report both clinician-relevant and patient-preferred outcomes at clearly defined perioperative, as well as long-term, time points.


Abdel-Hameed S.A.M.,National Research Center of Egypt | Margha F.H.,National Research Center of Egypt | El-Meligi A.A.,National Research Center of Egypt | El-Meligi A.A.,AMA International University Bahrain
International Journal of Energy Research | Year: 2014

SUMMARY: Crednerite glass-ceramic material (CuMnO2) has been investigated for the first time as a hydrogen storage candidate. The average gravimetric capacity is about 16g H2/kg and about 50g H2/kg of CuMnO2 at 473 and 573K respectively under a pressure up to 20bars. The hydrogen adsorbed capacity (weight percent) of CuMnO2 increased with increasing temperature. The material doesn't release hydrogen during desorption cycle revealing storage of hydrogen in the prepared material. X-ray diffraction patterns reveal a structure corresponding to Cu2O, CuMnO2, and traces of CuO and SiO2 phases. X-ray diffraction patterns exhibit a reduction of copper ions to copper metal beside cristobalite and traces from manganese oxide phase after exposing to H2 at 80 and 573K. This reduction of Cu ions into Cu metal may explain the irreversibility of hydrogen adsorption process. Thermal stability detected by differential scanning calorimetry and thermal gravimetric analysis shows decomposition temperature up to ~473K followed by gain of weight till 1173K then another decomposition till 1273K. © 2013 John Wiley & Sons, Ltd.


Fedorowicz Z.,AMA International University Bahrain
Cochrane database of systematic reviews (Online) | Year: 2012

Endodontic treatment, involves removal of the dental pulp and its replacement by a root canal filling. Restoration of root filled teeth can be challenging due to structural differences between vital and non-vital root filled teeth. Direct restoration involves placement of a restorative material e.g. amalgam or composite directly into the tooth. Indirect restorations consist of cast metal or ceramic (porcelain) crowns. The choice of restoration depends on the amount of remaining tooth which may influence long term survival and cost. The comparative in service clinical performance of crowns or conventional fillings used to restore root filled teeth is unclear. To assess the effects of restoration of endodontically treated teeth (with or without post and core) by crowns versus conventional filling materials. We searched the following databases: the Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE via OVID, EMBASE via OVID, CINAHL via EBSCO, LILACS via BIREME and the reference lists of articles as well as ongoing trials registries.There were no restrictions regarding language or date of publication. Date of last search was 13 February 2012. Randomised controlled trials (RCTs) or quasi-randomised controlled trials in participants with permanent teeth which have undergone endodontic treatment. Single full coverage crowns compared with any type of filling materials for direct restoration, as well as indirect partial restorations (e.g. inlays and onlays). Comparisons considered the type of post and core used (cast or prefabricated post), if any. Two review authors independently assessed trial quality and extracted data. One trial judged to be at high risk of bias due to missing outcome data, was included. 117 participants with a root filled premolar tooth restored with a carbon fibre post, were randomised to either a full coverage metal-ceramic crown or direct adhesive composite restoration. At 3 years there was no reported difference between the non-catastrophic failure rates in both groups. Decementation of the post and marginal gap formation occurred in a small number of teeth. There is insufficient evidence to support or refute the effectiveness of conventional fillings over crowns for the restoration of root filled teeth. Until more evidence becomes available clinicians should continue to base decisions on how to restore root filled teeth on their own clinical experience, whilst taking into consideration the individual circumstances and preferences of their patients.

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