PRACTICAL ROBUST GEOTECHNICAL DESIGN- METHODOLOGY AND APPLICATIONS

This dissertation advances the robust geotechnical design methodology by offering improvements, which makes it more efficient and practical for the design of geotechnical systems. Robust geotechnical design (RGD) methodology seeks an optimal design, which is insensitive to, or robust against, the variation in the uncertain input parameters (called “noise factorsâ€) by only adjusting the easy to control parameters (called “design parametersâ€). The main goal of robust design is to consider safety, cost and robustness simultaneously. Because the cost and the robustness are conflicting objectives, the multi-objective optimization that considers these two objectives while enforcing the safety constraint yields not a single best design but a set of non-dominated designs, which are neither superior nor inferior to one another. These non-dominated solutions form a Pareto front. All these non-dominated designs on the Pareto front are equally optimal in the sense that no improvement can be achieved in one objective without worsening in the other objective. To locate the best compromise between the objectives, knee point concept is often adopted. In this dissertation, the existing RGD methodology, different robustness measures, and different methods for locating the knee point are examined, followed by the development of a new simplified procedure for determination of knee point. The reliability-based RGD approach is also improved in efficiency by coupling the reliability analysis of the system performance and design robustness evaluation. A simplified and efficient procedure is also proposed to implement the RGD optimization procedure in the Microsoft Excel spreadsheet. With all improvements made in this research, the RGD approach can still be computationally challenging for the practicing engineer. In this regards, an efficient and practical RGD procedure using a Microsoft Excel spreadsheet is developed. Because the numerical software programs are often used to evaluate the system response, a response surface model is proposed to approximate the performance functions and integrated into the simplified RGD approach. The significance and practicality of the proposed simplified RGD methodology is illustrated with multiple geotechnical applications, including the design of shallow foundations, rock slopes, drilled shafts, and supported excavations

Significant association of TNF-α, but not other pro-inflammatory cytokines, single nucleotide polymorphisms with intervertebral disc degeneration in Iranian population

Objectives: As the important role of inflammation in pathophysiology of intervertebral disc degeneration and inconsistency regarding the role of pro-inflammatory cytokine genes SNPs, the current case-control study was designed to assess this in Iranian population. Patients and Methods: The genomic DNA of peripheral leukocytes of 76 patients and 140 healthy controls were investigated to sequence 9 SNPs of pro-inflammatory cytokine genes of interleukin 1 (IL1), interleukin 6 (IL-6), and Tumor Necrosis Factor α (TNF-α) family. Results: ‘GA’ and ‘GG’ genotype of TNF-α −308 G/A SNP were significantly associated with IVDD. While ‘GA’ was 1.93 times more frequent in patients, the ‘GG’ genotype was more common among healthy subjects (OR = 0.51, P = 0.03). The ‘G’ allele of TNF-α −238 G/A was 2.51 times more common in IVDD patients while the ‘A’ genotype was more frequent in controls with odds ratio of 0.39 (P = 0.001). Interestingly, the homozygote ‘GG’ genotype was 2.98 times more prevalent in patients (P = 0.001) while the ‘GA’ heterozygote genotype was more common in healthy individuals (OR = 0.34). The other investigated SNPs were not significantly associated with disease in this study population. Conclusion: Polymorphisms of pro-inflammatory cytokine genes could take part in IVDD pathophysiology as the result of alteration in their expression levels or structures. The current study indicated significant roles of TNF-α −308 G/A and TNF-α −238 G/A SNPs with IVDD among Iranian patients. However, this study did not show any significant association between IVDD and either of SNPs of IL-1 and IL-6 gene

Assessing Characteristic Value Selection Methods for Design with LRFD – A design robustness perspective

An important step in load and resistance factor design (LRFD) is the selection of the characteristic values of uncertainsoil parameters, which can be quite subjective despite the simplicity of LRFD. This paper assesses five statistical methods for theselection of characteristic values for design with LRFD, focusing on the design robustness. A framework based on the consider-ation of safety, cost, and design robustness is proposed for assessing these selection methods. This framework is illustrated withan example, the design of a drilled shaft in sand using LRFD, in which the best overall method for selecting the characteristicvalues is suggested. The implication of the outcome of this study is quite significant in geotechnical engineering practice, as itprovides guidance on the selection of the characteristic values for design with LRFDThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Understanding why oral health professionals migrate: A qualitative investigation of Iranian dentists who have moved to Canada (Oral health professionals’ migration)

Background The migration of health professionals from Low- and Middle-Income Countries (LMICs) to High-Income countries (HICs) is an ongoing phenomenon that has been accelerating with globalisation. While there has been growing research around the migration of physicians and nurses, there is less understanding of the motives surrounding the migration of dentists, and even less about their migration from specific countries. Objectives This qualitative study explores the migration motivations of Iranian dentists who have moved to Canada. Methods Semi-structured interviews of 18 Iranian-trained dentists in Canada were conducted to obtain information about their motives for migration. Interviews were coded and categorised into themes using qualitative thematic analysis. Results Motivations to migrate were grouped into four analytical areas: socio-political; economic; professional; and personal. An inverse relationship was identified between the strongest motives to migrate and the topics respondents were least comfortable discussing. Socio-political-related motives were predominant with respondents focusing on their dissatisfaction with the social ethos and restrictions on personal freedom within Iran. Conclusion Country-specific context is critical to fully understand health professional migration; in particular, the dynamics and interplay between socio-political, economic, and professional/personal factors within the home country. While Iranian dentists’ motives to migrate have some similarities to other health professionals who migrated from Iran, and dentists from other countries, differences need to be considered to fully understand migration patterns

Association of IL10 and TGFB single nucleotide polymorphisms with intervertebral disc degeneration in Iranian population: a case control study

Abstract Background Considered as one of the major causes of low back pain, Intervertebral disc degeneration (IVDD) is caused by several genetic and environmental factors. As inflammation plays an important role in disc degeneration, the genetic changes in both inflammatory and anti-inflammatory genes may play causative roles in IVDD as well. Therefore, the interactions between inflammatory and anti-inflammatory cytokines and also other components of disc matrix would determine the degree of tissue destruction in disc degeneration. However, there is still controversy regarding the exact role of inflammation and disc homeostasis imbalance in pathophysiology of IVDD. Therefore, current study was conducted to investigate the role of IL-10 and TGF-β single nucleotide polymorphisms (SNP) in Iranian IVDD patients. Methods Seventy-six IVDD patients and 140 healthy controls were enrolled in this study. Genomic DNA from peripheral leukocytes was tested for 3 SNPs in IL10 (L-10 -1082G/A (rs1800896), IL-10 -819C/T (rs1800871), IL-10 -592A/C (rs1800872)) and 2 SNPs in TGF-β (TGF-β Codon 10 C/T (rs1982037), and TGF-β Codon 25 C/T (rs1800471) genes through PCR-SSP method. The extracted genomic DNA was genotyped for the aforementioned SNPs of interest using specific primers, which were coated in the cytokines KITs and based on the PCR-SSP method for sequencing. Results The ‘T’ allele of IL-10 -819C/T and the ‘C’ allele of IL-10 -592A/C were more prevalent among patients, whereas the ‘C’ and ‘A’ alleles of respective SNPs were significantly more frequent in controls. The genotypes including ‘CT’ of IL-10 -819C/T, ‘CA’ of IL-10 -592A/C, and ‘GA’ of IL-10 -1082A/G were more common among patients, while the ‘CC’ genotype of both IL-10 -819C/T and IL-10 -592A/C SNPs were more frequent in controls. In addition, the IL-10 haplotypes including ‘ACC’, ‘ATA’, and ‘ACA’ were significantly associated with disease. Meanwhile, the ‘TC’ haplotype of TGF-β was more common among patients as well. Conclusions The IL-10 SNPs were significantly associated with IVDD in Iranian population; which proposes that genomic alterations of anti-inflammatory cytokines could lead to homeostasis imbalance in intervertebral discs and degenerative changes

The role of interleukin 4 and IL-4RA in intervertebral disc degeneration: investigation of single nucleotide polymorphisms in genes and a systematic review & meta-analysis of IL-4 expression level

Background: Intervertebral disc degeneration (IVDD) is a multifactorial disease that is sensitive to the balance between anti-inflammatory and pro-inflammatory cytokines. This study investigated the single nucleotide polymorphisms (SNPs) of interleukin 4 (IL-4) in IVDD. Methods: Genomic DNA of peripheral mononuclear cells of 76 IVDD patients and 140 healthy controls were investigated for three SNPs of IL-4 (rs2243248 (−1098G/T), rs2243250 (−590 C/T), rs2070874 (−33 C/T)) and 1 SNP of IL-4RA (rs180275, +1902 A/G) through PCRSSP method. Results: The ‘C’ allele frequency of IL-4 rs2243250 was 104 in 76 patients, while it was 149 in 140 controls (OR = 2, p =.001); also this SNP was significantly associated with post-operative pain reduction. The ‘C’ allele of IL-4 rs2070874 (130 in 76 patients, and 200 in 140 controls, OR = 2.66), and the ‘CC’ genotype were more frequent among patients (OR = 3.98, p <.001) than controls. ‘TTT’ haplotype was more common in controls (OR = 0.36, p <.001) and ‘TCC’ was also more common in patients (OR = 1.75, p =.012). A meta-analysis of previous studies found significantly higher IL-4 levels in disc tissues of IVDD patients, which was not similarly found in blood samples. Conclusion: The immune system plays an important role in IVDD. The extent and progress of the disease vary significantly with IL-4 level. Meanwhile, the rs2070874 and rs2243250 SNPs of IL-4 were significantly associated with IVDD in Iranian patients. Keywords: Intervertebral disc degeneration, single nucleotide polymorphism, interleukin 4, Interleukin-4 receptor alpha, immunogenetics, cytokin

Association of interleukin 2, interleukin 12, and interferon-γ with intervertebral disc degeneration in Iranian population

Background: Intervertebral disc degeneration (IVDD) is an age-related degenerative disease, presenting with low back pain or radicular pain. The inflammatory changes would occur in discs in the process of IVDD. Therefore, the inflammatory and anti-inflammatory cytokines, as well as their respective genes, have been proposed to play roles in pathophysiology of disease. This study has been conducted to elucidate the role of IL-2, IL-12, and IFN-γ single nucleotide polymorphisms (SNP) in this disease. Method: Seventy-six patients who were diagnosed with IVDD and 140 healthy controls who complied with eligibility criteria were included. A total volume of 5 cc peripheral blood was obtained from each participant to investigate the IL-2 + 166G/T, IL-2 -330G/T, IL-12 − 1188A/C, and IFN-γ +847A/T SNPs through PCR-SSP method. Results: The ‘TG’ and ‘TT’ genotypes of IL-2 − 330G/T polymorphism were significantly more common among patients and healthy controls respectively. The ‘GT’ and ‘TT’ haplotypes of IL-2 (comprised of -330G/T, and + 166G/T SNPs) were also more common among patients and controls respectively. Conclusion: This study indicated the significant role of IL-2 genotypes and haplotypes in IVDD. These SNPs were differently distributed in patients and controls. Therefore, alteration in the structure of IL-2 gene could play an important role in pathophysiology of IVDD. Keywords: Intervertebral disc degeneration, Single nucleotide polymorphism, Interleukin 2, Interleukin 12, Interferon γ, Immunogenetics, Cytokin