Preoperative CT Angiography Informs Instrumentation in Anterior Spine Surgery for Idiopathic Scoliosis.

The objective of this study is to evaluate whether the artery of Adamkiewicz localization with preoperative CT angiography influences anterior spinal instrumentation.MethodsChildren with idiopathic scoliosis who underwent anterior instrumentation and with a preoperative CT angiography were evaluated retrospectively. Data included curve type, artery of Adamkiewicz level/laterality, surgical approach laterality, number of instrumented levels and segmental vessels ligated, intraoperative neuromonitoring changes, and postoperative neural complications.ResultsThirty-nine girls and eight boys (mean age 12 years [6.7 to 16.8 years]) were analyzed. Instrumented curves indicate 28 thoracic, 14 thoracolumbar, and seven double major. The artery of Adamkiewicz: T6 (left-1), T8 (left-1), T9 (left-4/right-2), T10 (left-11/right-4), T11 (left-4/right-4), T12 (left-1/right-2), L1 (left-2/right-1), and L2 (left-3/right-2). Four had bilateral dominant segmentals, whereas in nine patients, none was identified. T10 (32%) and left side (57%) were most frequent. On average, 7.1 (4 to 11) segmentals were ligated per case (total 355). Dominant vessels were ipsilateral to/within instrumentation levels in 30%.DiscussionIn children with idiopathic scoliosis who underwent anterior instrumentation, the artery of Adamkiewicz was identified on the left in >50% and at T10 in 32%. In one-third of the patients, the artery was within intended surgical levels and resulted in instrumentation modification

A Comparative Analysis of the Determinants and Pricing of Liquidity in Floor and Electronic Trading Systems

In recent years many stock exchanges have moved away from floor-based to automated-based trading systems. However, the choice between these alternative trading systems is a major concern for stock exchange regulators and designers, and the impact of their merits on market characteristics (e.g. liquidity) is controversial. This thesis is motivated by the desire to shed light on this controversy, and therefore aims to offer a comparative analysis of various aspects of liquidity under floor and automated trading systems. More specifically, within the context of different trading systems (i.e. floor versus electronic), this thesis examines three empirical issues: firstly, the determinants of market-wide liquidity and its time-series behaviour; secondly, whether market-wide and firm-specific liquidity are priced in assets returns; and finally, whether the cross-sectional variations in firm-specific liquidity could be explained by the cross-sectional variations in information asymmetry and divergence of opinion. The findings of this thesis can be summarized as follows. Firstly, market-wide liquidity is significantly influenced by market returns, market volatility, interest rate variables and the announcement of macroeconomic indicators. Market-wide liquidity also shows distinct day-of-the-week regularities and a distinct pattern around holidays. The impact of some factors on market-wide liquidity, and the time-series behaviour of market-wide liquidity on the floor trading system in some markets is higher than that on the electronic trading systems. Secondly, market-wide liquidity has a significant impact on assets returns, and after controlling for its effect, firm-specific liquidity has a significant effect on risk-adjusted returns. The liquidity premium required on market-wide and firm-specific liquidity, for some proxies of liquidity in some markets, is higher on an automated trading system than on a floor trading system. Finally, firm-specific liquidity is negatively related to the level of information asymmetry. However, the evidence for the impact of divergence of opinion on firm-specific liquidity is inconclusive; a higher level of divergence of opinion results in higher liquidity, which supports the optimistic view; and firm-specific liquidity decreases with divergence of opinion, which is consistent with the view that disagreement among investors is a source of risk. Additionally, after automation, the impact of information asymmetry (divergence of opinion) on firm-specific liquidity is greater (lesser) than that before automation. Overall, this thesis demonstrates that the design and the structure of markets is closely linked to the latter’s performance and that the change to automated trading systems has significant implications for liquidity. As such, this study should be a valuable reference point for stock exchanges that have introduced automation, or are considering doing so

Key challenges for implementing a Canadian-based objective structured clinical examination (OSCE) in a Middle Eastern context

Globalization of medical education is occurring at a rapid pace and many regions of the world are adapting curricula, teaching methods, and assessment tools from established programs. In the Middle East, the use of Objective Structured Clinical Examinations (OSCEs) is rare. The College of Pharmacy at Qatar University recently partnered with the University of Toronto and the Supreme Council of Health in Qatar to adapt policies and procedures of a Canadian-based OSCE as an exit-from-degree assessment for pharmacy students in Qatar. Despite many cultural and contextual barriers, the OSCE was implemented successfully and is now an integrated component of the pharmacy curriculum. This paper aims to provide insight into the adoption and implementation process by identifying four major cultural and contextual challenges associated with OSCEs: assessment tools, standardized actors, assessor calibration, and standard setting. Proposed solutions to the challenges are also given. Findings are relevant to international programs attempting to adapt OSCEs into their contexts, as well as Canadian programs facing increasing rates of cultural diversity within student and assessor populations

Setting the agenda for clinical pharmacy in Qatar: thematic and content analyses of news media headlines

Public awareness of the role of pharmacists and availability of pharmacy services in Qatar is low. As per agenda-setting theory, mass media may be contributing toward this problem by selecting and disseminating headlines and stories according their own objectives and not those of the profession. The objective of this study was to examine the agenda set by mass media organizations in Qatar pertaining to the profession of pharmacy and to determine the frequency of professional identifiers that appear within news headlines. Publicly available news headlines published between November 2016 and November 2018 were obtained from local news websites. Thematic analysis was performed using agenda-setting theory to explore how the public's agenda was set for pharmacy practice in Qatar. Content analysis was used to determine the proportion of headlines that contained a professional identifier linking the news report to the pharmacy profession. A total of 81 headlines were included in the analysis. The agenda for pharmacy practice in Qatar was set according to two themes: achievement and outreach/engagement. Achievement related to awards, use of new technologies, interprofessional education, and novel student training accomplishments. Outreach/engagement reported student and pharmacist involvement upon completion of a health awareness event. Approximately half (47%) of headlines contained a professional identifying word linking the headline to the profession of pharmacy. The findings of this study demonstrate that the mass media's agenda for the pharmacy profession in Qatar does not inform the public of pharmacist's services or expanded scopes of practice. Furthermore, a lack of professional identifiers within headlines likely limits the public's agenda of pharmacist roles. The pharmacy profession must work collaboratively with news media to better align the public's agenda with pharmacists' roles and services

The Effect of Aluminum Cold Spray Coating on Corrosion Protection and Corrosion Fatigue Life Enhancement of Magnesium Alloy, AZ31B

Magnesium alloys are of a recent interest for the transportation industry due to their excellent properties such as high strength and low density which will save energy and reduce gas emission and it will also improve the vehicle performance. However due to their high chemical activity, magnesium and magnesium alloys have unsatisfactory corrosion resistance and high tendency to corrode in humid and aqueous environments. Although alloying elements provides some improvement in magnesium against corrosion, further protection for these alloys is needed against the corrosion in different corrosive environments. Aluminum powder cold spray is a new coating technology with very promising results in corrosion protection of magnesium alloys. The effect of applying pure aluminum cold spray coating on wrought AZ31B Mg alloy from the corrosion and corrosion fatigue point of view is studied. This research comprises two parts. The first part is studying the corrosion behavior of AZ31B cold spray coated and uncoated coupons by performing an accelerated corrosion testing in a corrosion chamber. The results for both types of coupons have been compared to each other. The second part of this research is to study the fatigue strength by rotating bending machine of stress relieved and stress relieved/coated specimens in salt water environment. S-N curves for the two groups of specimens were plotted. After the analysis and comparison of all the testing results, it was revealed that pure Al cold spray coating considerably improved the corrosion resistance of Mg alloy AZ31B in 5% NaCl fog environment. The microstructural analysis revealed the presence of some secondary phases which act as a cathode and accelerate the corrosion of the anode, Mg alloy. Comparison of corrosion-fatigue S-N curves of stress relieved and stress relieved/coated specimens show fatigue life reduction after cold spray coating to a maximum percentage of 87.6%. The reason for that is the fact that the pure Al powder has much lower ultimate tensile strength than Mg alloy AZ31B. This fact will lead to an earlier crack on the Al coating surface during the fatigue cycles, from which the electrolyte will penetrate to the Mg substrate and cause a localize corrosion and failure

Microstructure and mechanical properties of Al-Alloy with rare earth

The development of aluminum alloys is of great interest to many of the industries and biomedical applications, because they provide a high strength to weight ratio, high wear resistance, low density and low coefficient of thermal expansion compared with other materials. These improvements in the field of application make the study of their mechanical behavior of utmost importance. However, these alloys possess some limitations in terms of the interactive effects of additives. Therefore, the present study aims to investigate the influence of the rare-earth, e.g., Lanthanum and yttrium with the amounts of 0.5, 1.0, and 1.5 wt.% on the microstructure and mechanical properties of hypereutectic Al-Si and hypoeutectic Al-Mg alloys. The microscopic observations contain of optical, field emission scanning electron, energy dispersive spectroscopy and X-ray diffraction, and mechanical properties testing, such as tensile, impact, and hardness test were carried out. A good agreement was observed between the results of microstructure and mechanical properties. XRD and EDS results indicate the formation of intermetallic compounds that associated with the modifications, which may play a major cause in improving the mechanical properties. It was also found that the secondary dendrite arm spacing value became smaller with increasing La addition, and decreased slightly from the unmodified 5 µm to 4.1 µm. On the other hand, when the content of La is 1.0%, the iron-rich phases tend to be slender with a size of about 0.5 µm. While with the addition of 1.0 wt.% of Y, the volume fraction of the dendritic phase are tend to decrease along with increase the grain size to 40 µm. The modifications of Al-alloy eutectic structure were improved ductility from 0.7% and 8% to 1.8 and 10.5 with the addition of 1.0 wt.% of La and Y, respectively. However, the addition of 1.0 wt.% of La and Y led to increase the ultimate tensile strength from 100 MPa and 180 MPa to 150 MPa and 200 MPa, respectively. A further addition of La and Y results in a reduction in mechanical properties

Development of leukocytoclastic vasculitis during long-term methotrexate therapy in patients with rheumatoid arthritis: description of two clinical cases

Leukocytoclastic vasculitis (LCV) is a small vessel vasculitis characterized by immune complex depositions involving dermal post-capillary venules. Cutaneous small vessel vasculitis is most often idiopathic but may be aggravated by secondary causes, such as inflammatory conditions, infections, neoplasms, and drugs exposure.Herein, we describe two patients with a long history of rheumatoid arthritis (RA) treated with methotrexate (MTX) for more than ten years, who later developed generalized LCV with pancytopenia after a viral infection, one with herpes simplex virus, and the other with SARS-CoV-2 virus. Because of the worldwide use of MTX in treatment of RA, strict follow-up and preventive measures are needed nowadays, especially during COVID-19 pandemic, in order to avoid any infection which may provoke LCV with or without systemic manifestations. So, using MTX for treating RA or other similar disorders may be considered a double-edged sword, especially during COVID-19 pandemic.