Three-dimensional surface grid generation for calculation of thermal radiation shape factors

A technique is described to generate three dimensional surface grids suitable for calculating shape factors for thermal radiative heat transfer. The surface under consideration is approximated by finite triangular elements generated in a special manner. The grid is generated by dividing the surface into a two dimensional array of nodes. Each node is defined by its coordinates. Each set of four adjacent nodes is used to construct two triangular elements. Each triangular element is characterized by the vector representation of its vertices. Vector algebra is used to calculate all desired geometric properties of grid elements. The properties are used to determine the shape factor between the element and an area element in space. The grid generation can be graphically displayed using any software with three dimensional features. DISSPLA was used to view the grids

Nano-computed tomography: current and future perspectives

The development of novel imaging technologies amplifies the excellence of scientific dental research. Significant technological advances in imaging have been introduced over the years in the field of restorative dentistry and endodontics. X-ray micro-computed tomography (micro-CT) systems were developed in the early 1980s, producing voxels in the range of 5 - 50 μm.1 These micro-CT systems offer a reproducible technique for three-dimensional assessment. Because the imaging process is non-destructive, the same samples can be examined many times and continue to be available after scanning for additional biological and mechanical testing.1,2 In recent years, micro-CT systems have rapidly gained importance as essential components of many academic and industrial research laboratories, and have been used in examining a wide range of specimens including teeth, bone, and materials.1 Newer generations of micro-CT systems also enable in vivo imaging of small live animals.

Static and dynamic responses of prestressed concrete beams with openings.

Web openings in beams occur quite often in practice to provide convenient passage of environmental services. As a result, storey heights in buildings can be reduced resulting in major cost savings. Some openings generally give rise to excessive deflections and stresses which have to be taken into consideration. In this research, a theoretical and experimental study is carried out to determine the influence of openings on the static and dynamic responses of prestressed concrete beams. The effect of openings on the behaviour of such beams at different stages of loading--transfer stage, working stage, and ultimate stage--as well as under excitation of dynamic load, is presented. The influence of opening dimensions, horizontal and vertical locations, type of cross section on the static behaviour is investigated from the stand point of deformations, stresses, cracking, and ultimate strength capacity. Also the effect of these parameters as well as the number and dimensions of continuous spans on the natural frequencies, mode shapes, stresses, and deformations is presented. The results from a non-linear finite element static analysis are substantiated by static test results from thirteen post-tensioned prestressed concrete beams, six of which were rectangular in section, five were T-, and two were of I-section. Also the results from a finite element dynamic analysis are substantiated by dynamic test results in the literature. Good agreement is shown between the theoretical and experimental results. Furthermore, an extensive parametric study is performed on prestressed beams with openings to: develop a design procedure against cracking of the opening chords; estimate the beam maximum deflection; find the distributing ratio of the shear force between the opening chords; obtain the ultimate capacity of prestressed beams with openings; and determine the natural frequencies, and hence the dynamic response of simply supported and continuous prestressed beams with openings.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1993 .A333. Source: Dissertation Abstracts International, Volume: 54-09, Section: B, page: 4817. Adviser: J. B. Kennedy. Thesis (Ph.D.)--University of Windsor (Canada), 1993

Epidemiological study of risk factors in pediatric asthma

Background: Childhood asthma is a major public health problem in Egypt and worldwide. Epidemiologic, physiologic, and social factors appear to be associated with an increased risk of asthma. Objective: The aim of the study was to determine the most frequent risk factors of childhood asthma exacerbation and severity in our community. Methods: This cross sectional study involved 206 asthmatic children, 5 to 15 years old. They were enrolled from the School Students Health Insurance facility of El-Matareya Teaching Hospital and from the Pediatric Outpatient Clinic of Saint Mark Charity Hospital representing several social and residential classes. They were assessed clinically and by peak expiratory flow rate (PEFR). Parents of children were interviewed for symptoms and some demographic, social, environmental, housing and familial data as well as asthma triggers through a comprehensive detailed questionnaire. Results: Residential distribution and social status were significantly associated with asthma severity as most moderate persistent asthmatics lived in semi-urban areas (70.8%) and belonged to the low-level segment of social classification (47.9%). In the majority of the study population (69.9%), a family member or more had a positive history of bronchial asthma, and this was especially evident in moderate persistent cases (70.8%). Passive smoking and dust triggered exacerbations in 48.6% and 65% of the studied sample respectively and in most moderate persistent asthmatics (83.4% and 93.7%). Most houses of moderate asthmatics were infested with cockroaches (91.7%) and domestic animals were present in 56.2%. Recurrent chest infections and cold/flu attacks were strongly associated with asthma exacerbation and severity (93.8% and 93.7% of moderate persistent cases respectively). Most moderate persistent asthmatics (91.7%) reported exercise-induced asthma while 64.6% stated that emotional stress triggered their symptoms. Indoor pollutants such as insecticides, household chemicals and odors were strongly associated with asthma severity and exacerbation especially in moderate persistent cases (triggered symptoms in 66.7%, 52.1% and 58.3% of cases respectively). Conclusion: Smoking, emotional stress and dust were the most significant triggers of asthma exacerbation and severity in our series. Identification and avoidance of risk factors for persistent asthma, combined with early institution of pharmacologic and other intervention strategies, may lead to a better outcome.Keywords: asthma severity; asthma triggers; children; residence; risk factors; smoking; social statusEgypt J Pediatr Allergy Immunol 2007; 5(1): 11-1

Epidemiological study of school performance and asthma medications among asthmatic Egyptian school children

Background: Childhood asthma is a major health problem in Egypt and worldwide. Barriers to reducing the burden of asthma include symptom-based rather than disease-based approaches, tendency of care to be ‘‘acute’’ rather than “regular” and cultural attitudes towards drugs and drug delivery systems. Objective: To measure the disease effect on school performance and to map asthma medications with respect to types, routes and course of use. Methods: This cross sectional study involved 206 Cairene asthmatic school children, enrolled from the school students’ health insurance facility of El-Matareya Teaching Hospital and the pediatric outpatient clinic of Saint Mark Charity Hospital representing different social classes and residential locations. Their ages ranged between 5 and 15 years and they comprised 100 males and 106 females. They were assessed clinically and by peak expiratory flowmetry. Parents or caregivers were interviewed about disease symptoms, school achievement and attendance and medications used including relievers and controllers, route and course of use, whether continuously, intermittently and/or during attacks. Results: Asthma had a strong impact on school achievement and school absence; 77.3% of study population reported school absence due to asthma and 41.3% reported weak to average school achievement. School performance was associated with asthma severity; the majority of moderate asthmatics (64.6%) had average and weak school performance. Number of days of school absence demonstrated highly significant relation with asthma severity; 43.6% of moderate asthmatics had 5-6 absent days/month and 33.4% had 3-4 absent days/month. Combined β2-agonists and xanthines was the most commonly used (54.8%) reliever therapy followed by β2-agonists alone (44.2%) while corticosteroids were the most common controllers used (97.6%). Therapy was taken mainly by oral than inhalation route. Other medications like cromolyns, anti-histamines, anti-leukotrienes and anti-cholinergics were rarely used. Both rectal and injection routes were rarely used also. Conclusion: Asthma has a social burden on asthmatic children as it affects both school achievement and school attendance. Medical management of asthma in Egyptian children still lags behind available medical knowledge. Patients’ and health care givers’ education is a cornerstone in improving the current status of asthma management in Egypt.Keywords: asthma medications; asthma severity; children; school performanceEgypt J Pediatr Allergy Immunol 2009;7(1):23-3

Maternal inflammatory bowel disease, racial diversity and adverse birth outcomes

Background: Inflammatory bowel disease (IBD) is a term used to describe two conditions, Crohn’s disease and ulcerative colitis (UC), that currently have no definite cure. The incidence of IBD worldwide has increased, frequently affecting women during their reproductive years. Objectives: This study examines the association of Crohn\u27s disease and ulcerative colitis (UC) with adverse pregnancy outcomes and looks at the interactions of race/ethnicity on these associations. Study Design: We examined hospital birth records in the National Inpatient Sample (NIS) data sets in 2011 and 2012. We identified maternal demographics and clinical characteristics using international classification of disease-9 codes. Chi-square and Fisher exact tests were used to examine associations and logistic regression models were used to control for confounders. Results: Crohn\u27s disease is associated with small for gestational age, aOR 1.70(CI:1.53-1.89,p<0.001) but not premature delivery, whereas UC was associated with prematurity, aOR 1.5(CI:1.36-1.66,p<0.001) to a greater extent than with SGA. Analyses by race/ethnicity showed Crohn’s disease to be associated with SGA among newborns of all racial groups, but most evident among African Americans, aOR 2.55(CI:2.06-3.15,p<.001). Crohn’s disease was associated with prematurity only in Caucasian women, aOR 1.21(CI:1.10-1.34,p<.001). UC was associated with SGA newborns only in Hispanic mothers, aOR 3.40(CI:2.24-5.15,p<0.001), and with premature delivery only among Caucasian mothers, aOR 1.60(CI:1.42-1.80,p<.001). Conclusion: Both Crohn\u27s disease and ulcerative colitis are associated with prematurity and small for gestational age in a way that is significantly affected by maternal race. Qualitative studies are needed to understand mechanisms for these associations and the role of race/ethnicity

Emerging antimicrobial resistance in early and late-onset neonatal sepsis

Background Compared to developed countries, the use of antimicrobials in Egypt is less regulated and is available over the counter without the need for prescriptions. The impact of such policy on antimicrobial resistance has not been studied. This study aimed to determine the prevalence of early and late onset sepsis, and the frequency of antimicrobial resistance in a major referral neonatal intensive care unit (NICU). Methods The study included all neonates admitted to the NICU over a 12-month period. Prospectively collected clinical and laboratory data were retrieved, including blood cultures and endotracheal aspirate cultures if performed. Results A total of 953 neonates were admitted, of them 314 neonates were diagnosed with sepsis; 123 with early onset sepsis (EOS) and 191 with late onset sepsis (LOS). A total of 388 blood cultures were obtained, with 166 positive results. Total endotracheal aspirate samples were 127; of them 79 were culture-positive. The most frequently isolated organisms in blood were Klebsiella pneumoniae (42%) and Coagulase negative staphylococcus (19%) whereas in endotracheal cultures were Klebsiella pneumoniae (41%) and Pseudomonas aeruginosa (19%). Gram negative organisms were most resistant to ampicillins (100%), cephalosporins (93%–100%) and piperacillin-tazobactam (99%) with less resistance to aminoglycosides (36%–52%). Gram positive isolates were least resistant to vancomycin (18%). Multidrug resistance was detected in 92 (38%) cultures, mainly among gram negative isolates (78/92). Conclusions Antibiotic resistance constitutes a challenge to the management of neonatal sepsis in Egypt. Resistance was predominant in both early and late onset sepsis. This study supports the need to implement policies that prohibits the non-prescription community use of antibiotics

Critical analysis of a new system to classify root and canal morphology — A systematic review

A novel system to classify root and canal morphology was recently introduced (Ahmed et al. 2017). This systematic review aimed to answer the following research question: Does the Ahmed et al. system provide a more accurate and practical classification of root and canal anatomy compared to other classifications? A literature search was conducted in Google Scholar, Scopus and Wiley Online Library to identify the citation counts for the article entitled ‘A new system for classifying root and root canal morphology; doi.org/10.1111/iej.12685’. After removal of duplicates and unrelated articles, 15 studies were included and analysed. All studies compared the Ahmed et al. system with the Vertucci classification. Results revealed that both systems were able to classify simple canal configurations in single‐rooted anterior and premolar teeth, disto‐buccal and palatal roots of maxillary molars. However, the Ahmed et al. system provided more accurate and comprehensive categorisations of single‐rooted teeth with complex canal anatomy, multi‐rooted maxillary and mandibular premolars and the mesio‐buccal root of maxillary molars. Further evidence on the utility of the Ahmed et al. system is required using other diagnostic devices especially in molars