Navigating Through Crisis: A Comparative Efficiency Analysis of Combination Carriers Before and During the COVID-19 Pandemic

COVID-19 had a devastating impact on the airline industry. During the pandemic, the continued and, to some extent, growing air cargo demand kept many airlines afloat. According to the International Airport Association, the pandemic devastated the aviation industry. Cessation of travel and border closures hinder the airlines’ primary cash source - passenger transportation revenues. Combination carriers, carriers with Dedicated Freighter Airplanes (DFAs), started developing innovative solutions to utilize their fleets to benefit from the heightened air cargo demand during the pandemic. This study studies global combination carriers’ operational and scale efficiency before, during, and after the COVID-19 pandemic. The study used the DEA, window analysis, and Malmquist Productivity Index methodologies to assess global combination carriers’ operational and scale efficiency from 2018 to 2021. The result shows how certain airline strategic decisions allow them to face the pandemic-imposed challenges and convert them into growth opportunities. The results also suggest that air cargo operational efficiency does not primarily depend on the number of bases the airline operates from, the air cargo generated from its base, or the number of DFAs in the fleet. Indeed, these factors support the operation; however, the increase in these factors does not necessarily translate into better operational or scale efficiencies. It is rather a strategic deployment of resources that leads to the airline’s success. The results also show that airlines focus on their internal efficiency when the industry productivity is not increasing

Restriction in the voters\u27 lists for the House of Representatives in Bahrain

The aim of this study is to point out one of the preliminary procedures the electoral process in the Kingdom of Bahrain goes through as a preparatory process for electing the members of the House of Representatives of Bahrain. This is the process of registration in the voters’ list. This has taken place after the process of democratic and political reform has firmly been established in the form of public participation. We are at the beginning of the third legislative term and the manner that the Bahraini Judiciary controls the process of registration shows to us the positive and negative aspects that have emerged out of this process. Therefore, this study has pointed out the general provisions for inclusion in the voters’ lists to elect the members of the House of Representatives of Bahrain in terms of the definition of registration and its importance. This study also shows how to prepare, review, display and object to the voters’ lists. It also pinpoints to how to change and vary the registration as well as to how the control of the Bahraini judiciary over these procedures and its authority towards such procedures is conducted. Finally, we have concluded with some recommendations to be considered by the Bahraini legislators if they wish to amend the decree by law no. (14) of 2002 concerning practicing the political right

TUNNELING STUDY OF SUPERCONDUCTIVITY IN MAGNESIUM DIBORIDE

Although the pairing mechanism in MgB2 is thought to be phonon mediated, there are still many experimental results that lack appropriate explanation. For example, there is no consensus about the magnitude of the energy gap, its temperature dependence, and whether it has only one-gap or not. Many techniques have been used to investigate this, like Raman spectroscopy, farinfrared transmission, specific heat, high-resolution photoemission and tunneling. Most tunneling data on MgB2 are obtained from mechanical junctions. Measurements of energy gap by these junctions have many disadvantages like the instability to temperature and field changes. On the other hand, sandwich-like planar junctions offer a stable and reliable measurement for temperature dependence of the energy gap, where any variation in the tunneling spectra can be interpreted as a direct result from the sample under study. To the best of our knowledge, we report the first energy gap temperature- and magnetic field-dependence of MgB2/Pb planar junctions. Study of the temperature-dependence shows that the small gap value (reported by many groups and explained as a result of surface degradation) is a real bulk property of MgB2. Moreover, our data is in favor of the two-gap model rather than the onegap, multi-gap, or single anisotropic gap models. The study of magnetic field effect on the junctions gave an estimation of the upper critical field of about 5.6 T. The dependence of energy gap on the field has been studied as well. Our junctions show stability against temperature changes, but collapsed when the magnetic field (applied normal to the junction barrier) is higher than 3.2 T. The irreversible structural change switched the tunnling mechanism from quisiparticle tunneling into Josephson tunneling. Josephson I-V curves at different temperatures have been studied and the characteristic voltages are calculated. The estimated MgB2 energy gap from supercurrent tunneling in weak link junctions agrees very well with that from quasiparticle tunneling. Reported properties on polycrystalline, single crystal and thin film MgB2 samples are widely varied, depending on the details of preparation procedure. MgB2 single crystals are synthesized mainly by heat treatment at high temperature and pressure. Single crystals prepared by this way have the disadvantages of Mg deficiency and shape irregularity. On the other hand, improving the coupling of grain boundaries in polycrystalline MgB2 (has the lowest normal state resistivity in comparison to many other practical superconductors) will be of practical interest. Consequently, we have been motivated to look for a new heat treatment to prepare high quality polycrystalline and single crystal MgB2 in the same process. The importance of our new method is its simplicity in preparing single crystals (neither high pressure cells nor very high sintering temperatures are required to prepare single crystals) and the quality of the obtained single crystal and polycrystalline MgB2. This method gives high quality and dense polycrystalline MgB2 with very low normal state resistivity (σ(40 ) = 0.28 cm). Single crystals have an average diagonal of 50 m and 10 m thickness with a unique shape that resembles the hexagonal crystal structure. Furthermore, preparing both forms in same process gives a great opportunity to study inconsistencies in their properties. On the other hand, magnesium diboride thin films have also been prepared by magnetron sputtering under new preparation conditions. The prepared thin films have a transition temperature of about 35.2 K and they are promising in fabricating tunnel junctions

Wireless Sensor Technology Selection for I4.0 Manufacturing Systems

The term smart manufacturing has surfaced as an industrial revolution in Germany known as Industry 4.0 (I4.0); this revolution aims to help the manufacturers adapt to turbulent market trends. Its main scope is implementing machine communication, both vertically and horizontally across the manufacturing hierarchy through Internet of things (IoT), technologies and servitization concepts. The main objective of this research is to help manufacturers manage the high levels of variety and the extreme turbulence of market trends through developing a selection tool that utilizes Analytic Hierarchy Process (AHP) techniques to recommend a suitable industrial wireless sensor network (IWSN) technology that fits their manufacturing requirements.In this thesis, IWSN technologies and their properties were identified, analyzed and compared to identify their potential suitability for different industrial manufacturing system application areas. The study included the identification and analysis of different industrial system types, their application areas, scenarios and respective communication requirements. The developed tool’s sensitivity is also tested to recommend different IWSN technology options with changing influential factors. Also, a prioritizing protocol is introduced in the case where more than one IWSN technology options are recommended by the AHP tool.A real industrial case study with the collaboration of SPM Automation Inc. is presented, where the industrial systems’ class, communication traffic types, and communication requirements were analyzed to recommend a suitable IWSN technology that fits their requirements and assists their shift towards I4.0 through utilizing AHP techniques. The results of this research will serve as a step forward, in the transformation process of manufacturing towards a more digitalized and better connected cyber-physical systems; thus, enhancing manufacturing attributes such as flexibility, reconfigurability, scalability and easing the shift towards implementing I4.0

Stress and Coping Strategies Among Final Dental Students at Karary University 2021

Background: Stress is a situation where the demands exceed the capacity of an individual to respond and can affect negatively the physical and psychological consequences. Dentistry can be extremely stressful for dental students who need to acquire different proficiencies such as theoretical knowledge, clinical skills, and interpersonal communication skills. The purpose of this study was to evaluate the sources of stress among dental students at the clinical stage, their perceived levels of stress, and the coping strategies they adopt. Methods: This is a cross-sectional study, which was conducted during the final semester of the academic year 2020-2021 at the College of Dentistry, Karary University, Sudan. We used the Perceived Stress Scale (PSS-10) and dental environmental stress scale (DES) questionnaire to evaluate stress among the selected students. The surveys were conducted among 78 dental clinical students (51 female and 27 male) and were asked to assess the different forms of stress they had been exposed to during the previous months. Descriptive analysis methods, Chi-square test, Pearson Correlation, and analysis of variance test (ANOVA) were performed to analyze the data. Results: Analysis indicated that there was a significant association between perceived stress scale and age (P < 0.05). Also, there was a significant association between gender and stress, Females were exposed to high PSS more than males with percentages of 54.9%. Our results indicated that the main sources of extreme stress among dental students were Compliance of patients (63.60%), Completing clinical requirements (62.30%), inadequate time for relaxation (57.70%), Insufficient treatment time (57.10%), academic factors (57.10%), reduced holidays (55.10%), Discrimination between students (46.10%), Lack of recreation places within the accommodation (42.3%) and financial problems (42.30%). To cope with stress, students used multi-factorial strategies, spiritual comfort, and sleeping. Conclusion: The primary sources of stress were academic factors and clinical education. The females expressed higher levels of stress in certain areas of dental training. the Present study identified stressors affecting dental students' academic life and highlights the importance of stress management programs and other measures to minimize the impact of stress on both the academic and personal lives of the students. Keywords: stress, PSS, DES, Dental Students, Coping Strategies

Experimental and Numerical Study on the Hydrodynamic Performance of Suspended Curved Breakwaters

The purpose of breakwaters is to protect the ports, beaches, or beach facilities from strong waves and storms, as they help establish calm inside the port and thus achieve safety for ships and ease of operation. This paper presents an experimental and numerical study of unconventional alternatives to the vertical breakwater in order to evaluate the hydrodynamic performance of the proposed models. Two proposed cases for a semi-submerged breakwater were selected in the form of a half-pipe section with an inside diameter of 20 cm and a thickness of 1 cm. Case (a) was of the concave type of semicircular breakwater, while case (b) was of the convex type. Numerical modeling FLOW 3D was used to construct numerous scenarios for numerical simulation of the proposed breakwaters. The obtained results indicates that, when comparing the wave transmission coefficient (Kt) and its reflection coefficient (Kr) with the relative water depth (h/L), the transmission coefficient decreased with the relative height of the wave, while the reflection coefficient was completely reversed. In case (a), Kt was less than in case (b) at a range of 10% to 15%, while Kr in case (a) was bigger than in case (b) at a range of 5% to 10%. When the wave hit the breakwater, it was reflected back as its energy is dissipated in less water depth and its speed decreases as it approaches the port. The velocity of the wave decreases as it approaches the bottom, which means that the wave is affected by the depth of the water, i.e. the lower the water depth, the lower the wave velocity. Case (a) was more efficient and effective in wave dissipation, current velocity, and bed stability than case (b), so it is recommended to use case (a) due to its efficiency in protecting coastal areas and generating electricity

Outcome Prediction after Surgical Management of Prosthetic Mitral Valve Dysfunction; a single center experience

Background: Prosthetic Mitral valve dysfunction is a serious complication associated with a high mortality rate particularly in obstructive cases. The number of cases undergoing redo mitral valve surgery is increasing. This study aims to identify the risk factors of mortality and morbidity in patients who underwent redo mitral valve surgery for prosthetic mitral valve dysfunction. &nbsp; Methods: This study was conducted on 80 patients who underwent re-operation for management of prosthetic mitral valve dysfunction from December 2014 to February 2018. Patients’ age ranged between 21 and 58 years with a mean of 36.8±9.60 years, and 53 patients (66.3%) were males. The causes of mitral valve malfunction were thrombus in 67 patients (83.7%) and pannus in 13 patients (16.3%). Results: 53 patients (66.25%) had urgent surgical intervention. Thrombectomy or pannus resection was done in 75 patients (93.75%) and valve replacement in 5 patients (6.25%). Re-exploration was required in 11 patients (13.75%) and was significantly associated with diabetes (p= 0.004), preoperative liver dysfunction (p= 0.04), elevated INR (p= 0.006), trial of thrombolysis (p&lt;0.001) and prolonged ischemic time (p= 0.01). Postoperative renal failure occurred in 11 patients (13.75%) and was associated with diabetes (p&lt; 0.001), preoperative renal dysfunction (p&lt; 0.001), prolonged cardiopulmonary bypass and ischemic times (p&lt; 0.001). 17 patients (21%) required prolonged mechanical ventilation and it was significantly associated with chronic obstructive lung disease (p&lt; 0.001), pulmonary edema (p &lt;0.001), low systolic blood pressure (p &lt;0.001), low ejection fraction (p&lt;0.001) and thrombectomy (p&lt;0.001). Operative mortality occurred in 13 patients (16%) and was significantly associated with preoperative stroke, renal dysfunction, low blood pressure and acute pulmonary edema (p &lt;0.001). Conclusion: Reoperation for prosthetic mitral valve dysfunction is associated with high morbidity and mortality. Outcomes can be predicted based on preoperative clinical status and operative times. Thrombectomy and pannus resection with the repair of the paravalvular leak is a simple and easy technique for management of those patients with a reduction of cardiopulmonary bypass and cross-clamp times