Validation of the Energy-Based Method for Evaluating Soil Liquefaction in Centrifuge

Extensive research has been conducted at Case Western Reserve University to introduce and evaluate the energy concept in defining the liquefaction potential of soils when subjected to dynamic loads. Generalized relationships were obtained by performing regression analyses between the energy per unit volume at the onset of liquefaction and liquefaction affecting parameters. This study deals with evaluating and examining the suitability of these relationships using centrifuge modeling. Centrifuge liquefaction testing of several soils with different grain-size characteristics made it possible to evaluate the validity of the energy method in determining the liquefaction potential of a soil deposit. Dynamic centrifuge tests were conducted on scaled pore fluid-saturated models, prepared in a laminar box, representing a prototype thickness of 7.6 m. A simplified procedure for estimating the energy per unit volume from the recorded horizontal accelerations and the lateral displacements at different depths is presented. The total energy at the onset of liquefaction is obtained from the stress-strain time histories from centrifuge testing results and compared with the same energy calculated from regression equations developed through torsional series tests. A rational procedure to decide whether or not liquefaction of a soil deposit is imminent can be formulated by comparing the calculated unit energy from the time series record of a design earthquake with the resistance to liquefaction in terms of energy, based on in situ soil properties

The impact of stone composition on renal function

Background: Nephrolithiasis is a common condition that has various classifications according to stone composition. Stone formation can affect renal function; it can be a strong risk factor for chronic kidney disease (CKD). The main objective of this study is to explore the association between creatinine clearance and different stone compositions. Methods: This is a retrospective cohort study conducted in a tertiary center in Jeddah, Saudi Arabia, between 2005 and 2014. Renal function was assessed by the estimating glomerular filtration rate (eGFR) by the Cockcroft-Gault equation. Stone composition was determined by urinary calculi analysis with infrared spectrometry. Results: Stones of 365 patients, with a mean age of 48.2 ± 13.6 years and a male to female ratio of 3.2:1, were analyzed. Stage 2 CKD has been documented. It involved oxalate, struvite, cystine, and uric acid stones. The worst eGFR was reported for stones containing uric acid. The eGFR was least affected with apatite stones followed by brushite stones. Conclusion: Stone disease can affect renal function. Different stone compositions show factor for renal impairment, and this should be considered in patient management. A special precaution should be considered for higher risk groups. Multidisciplinary patient care and immediate referral to a nephrologist are strongly advised

Combined Genetic Biomarkers Confer Susceptibility to Risk of Urothelial Bladder Carcinoma in a Saudi Population

We evaluated the associations between seven single nucleotide polymorphisms and susceptibility to urothelial bladder carcinoma (UBC) in a Saudi population. Genomic DNA was taken from buccal cells of 52 patients with UBC and 104 controls for genotyping of GSTT1, GSTM1, rs4646903, rs1048943, TP53 rs1042522, rs1801133, and rs1801394 using PCR and TaqMan® assays. The rs1801133 and rs1801394 variants showed strong associations with UBC (OR = 2.3, P=0.0002; OR = 2.6, P=0.0001, resp.). Homozygosity of Pro72 conferred a significant double risk in cases compared with controls (30.8% versus 15.4%), but the homozygote Arg/Arg had no effect on risk. Genotypic combinations of GSTM1/GSTT1, rs4646903/rs1048943, and rs1801133/rs1801394 exhibited significant linkage with the disease (χ2=10.3, P=0.006; χ2=13.9, P=0.003; and χ2=20.4, P=0.0004, resp.). The GSTM1 and rs1042522Arg and rs1801394G variant alleles were more frequent in current smokers with UBC (52.4%, 52.5%, and 64.3%, resp.) than were the corresponding wild-types. Despite some variants having only a slight effect on UBC risk, the interaction effect of combined genetic biomarkers—or even the presence of one copy of a variant allele—is potentially much greater. Perhaps more studies regarding next-generation genetic sequencing and its utility can add to the risk of UBC