Impact of Protracted War Crisis on Dental Students: A Comparative Multicountry Cross-sectional Study

BACKGROUND: The impact of conflict and war crisis on dental students is poorly understood. Given the prolonged conflicts and political instability in the Arabic-speaking countries, it is crucial to investigate the effect of these conditions on dental students. This study aimed to assess the impact of protracted war on dental students by comparing the personal, university, and wider context challenges they face across war-affected and unaffected countries. METHODS: A cross-sectional study was conducted including a convenience sample of dental students from 13 universities in 12 Arabic-speaking countries. Respondents were those at entry and exit points of their undergraduate dental training. A self-administered paper questionnaire collected anonymized data on sociodemographics, and personal, university, and wider context challenges that students were facing. Multivariable Poisson regression analyses were carried out. RESULTS: The overall response rate was 64.8%. The mean age was 21.2 (standard deviation = 2.1) years, with 68% of participants being female. After adjusting for age and sex, dental students in Arabic-speaking countries affected by protracted war crisis were significantly more likely to report wider context challenges compared to their counterparts in unaffected countries (n = 2448; beta = 1.12; 95% confidence interval: 1.10-1.13; P < 0.001). DISCUSSION: Dental students in Arabic-speaking countries affected by protracted war crisis were more likely to suffer from wider context challenges such as difficulties in attendance due to the deterioration of security and lack of flexibility of teaching time to accommodate the different circumstances induced by the war crisis. Supporting dental students in areas affected by protracted war crises is needed and may include developing online dental education programs

Yusuf bin 'Abdi al Barri al Qurthubi

168 hal.; 19 c

Prinsip-prinsip dan metoda pendidikan Islam : dalam keluarga di sekolah dan di masyrakat

Buku ini merupakan sebagai terjemahan dari Kitab Ushulut Tarbiyatun islamiyah wa Asalibuha' Karya Abdurrahman an nahlawi. Buku ini merefleksikan dua hal tentang pendidikan, yaitu keterpautan antara aspek dasar teoritis dengan aspek oerasional dan praktis

Ushulu Al Tarbiyah Wa-Asalibiha fil Bait wal Madrasah wal Mujtama'

282 Hal.; 21 C

al Imam al Dzahabi

158 hal.; 19 c

Hydrogen interaction with defects in metals.

Numerical calculations using Fermi-Dirac form have been performed to estimate the number of hydrogen atoms trapped at dislocations and grain boundaries as a function of the bulk concentration of hydrogen and temperature in palladium which is a face centered cubic structure. The calculations performed include the trapping of hydrogen atoms at both the dislocation core and strain fields surrounding the defects. The results of these calculations agree with the SANS measurements previously carried out by Heuser et al. at a hydrogen bulk concentration of 5500 parts per million. Heuser et al.'s results indicate that 2.6 hydrogen atoms per Angstrom and 0.4 $\pm$ 0.2 hydrogen atoms per square Angstrom are trapped at the dislocations and grain boundaries, respectively. For the purpose of this research, an assumption is made that the defects are edge dislocations and low angle grain boundaries. Numerical calculations are performed at various hydrogen bulk concentrations ranging from a few hundred to a few thousand parts per million. At a bulk concentration of 5500 ppm, the total calculated amount of hydrogen trapped at dislocations is 2.3 atoms per Angstrom of dislocation line and 0.2 atoms per square Angstrom of grain boundary area. The calculations indicate that about seventy-five percent of the trapped hydrogen lies within 5 to 8 Burgers vectors of the dislocation center. Depending on the core size and number of trapping sites assumed in the calculations, up to eighty percent of the total number of hydrogen atoms are found to be trapped in the core region which can be used to determine the core binding energy of hydrogen to these metal defects. The core binding energy is calculated to be 0.3 eV. At a bulk concentration of 5500 ppm, and temperature of 77 K, the calculations show an enhancement of ten times of hydrogen concentration in the neighborhood of the dislocations. Based on the results of the present mode a set of SANS experiments is proposed which will allow an accurate determination of the core energy, number of sites and core radius in dislocations.Ph.D.Nuclear EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/104248/1/9513287.pdfDescription of 9513287.pdf : Restricted to UM users only

An experimental and analytical study of shear strength of lightly reinforced concrete beams.

Designing for shear in reinforced concrete members is a complicated process. The current empirical shear equations were derived from testing hundreds of beams without a real fundamental underst and ing of shear behavior. This study deals with two primary factors; concrete strength and the amount of web reinforcement. One objective of this study was to extend current truss models to predict the complete shear behavior of reinforced concrete beams with and without web reinforcement. Experiments were undertaken on twenty-five short rectangular beams with low longitudinal reinforcement ratios. The stirrup spacing ranged from 0 (no stirrups) to d/3. The beams were designed to fail in shear. Strain gages were attached to the stirrups and longitudinal reinforcement. Targets were fastened to the side of the beam over half the beam span to measure the strain on the face of the beam. Test results indicated that the conservativeness of the ACI Code equations decreases as the concrete strength increases. An equation for minimum transverse reinforcement as a function of the concrete strength was proposed as an alternative to the existing ACI Code Equation. Having obtained the minimum web reinforcement ratio, the experimental and analytical results are used to define the maximum stirrup spacing. It is recommended to reinforce beams with low longitudinal reinforcement ratio ($\\rho\\sb\\omega < 1\\%)$ with a minimum transverse reinforcement ratio irrespective of the shear stress in the beam. Also, equations for predicting the shear strength are proposed. A modified truss model is developed to give a designer a better underst and ing of the behavior of the members, the force flow inside the member and the contribution of each material in resisting the applied forces. An analysis with the truss model using an angle of inclination between 30 and 35 deg. predicts the failure load reasonably well. A truss model for predicting the failure load for beams without transverse reinforcement is also developed. A 35 deg. angle of inclination gives satisfactory results. To maintain an angle above 25 deg. as suggested by Schlaich, Ramirez, and Rogowsky, a concrete tension member is included in the truss model. Thus, it is possible to predict the failure load for any beam with any shear span to depth ratio.Ph.D.Civil engineeringUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/162280/1/9001593.pd