Predicting Hydraulic Fracturing in Hyttejuvet Dam

Hydraulic fracturing can occur in the clay core of earth and rockfill dams if the vertical effective stress in the core is reduced to the levels that are small enough to allow a tensile fracture to occur due to hydraulic pressure of the seeping water. This situation may arise if the total stress in the core is reduced by the “arching effect” where the core settles relative to the filter or rock-fill shell of the dam. Water pressure increase in the core which occurs on first impounding of water, may reduce effective stresses further, and if they reach low enough values, a fracture will occur. The design of earth dams (especially those with thin vertical central cores) to resist hydraulic fracture is therefore of great importance, as there have been several dam failures in the past that have been attributed to the hydraulic fracture. In this paper, the behavior of Hyttejuvet Dam, which was thought to have failed due to hydraulic fracturing, is studied. 2D coupled consolidation finite element analysis of the construction and first impounding of the rockfill dam was carried out with elasto-plastic model (Drucker-Preger/Cap model) using ABAQUS software. The result of the analysis with respect to the pore pressure and settlement in some parts of the dam are compared with the measured data from the instruments in the dam. According to the result of the comparison, the appropriate model for predicting the behavior of Hyttejuvet Dam is obtained. Also different criteria are used to predict the hydraulic fracturing of the dam. By comparing the results of the study using these criteria, one may be able to predict the hydraulic fracturing mechanism in the clay core of the studied dam

Efficacy of Probiotic Escherichia coli Nissle 1917 in Patients with Irritable Bowel Syndrome: a Double Blind Placebo-controlled Randomized Trial

AIM: to evaluate potential improvement effect for probiotic E. coliNissle 1917 in the management of refractory IBS in an Iranian population. METHODS: a double blind placebo controlled approach has been used in the current clinical trial. 139 confirmed IBS patients were included into the study, and were given probiotic E.coli Nissle 1917 for 6 weeks. 11 items Birmingham IBS Symptom Questionnairehas been used for evaluation of changes in the symptoms every 2 weeks. CONCLUSION: probiotic therapy with E.coli Nissle 1917 was not able to induce significant improvement in the symptoms of patients with non-categorized IBS. Nevertheless, when IBS patients were recategorized to subgroups according to their main symptoms, evaluation of the efficacy of the probiotic on some individual items in the symptom list reached the significance level. Prospective clinical trials are recommended to confirm our findings. RESULTS: sixty eight subjects (49) were males. Mean±SD age of the participants was 38±13.3 years. 49(35.3) of the patients were diarrhea-predominant. The total scores showed no significant difference between the intervention vs. control group(-6.7±6.8 vs. -6.7±6.5, respectively; p=0.95); neither did any of the questionnaire items any significant alterations in the two groups. After stratification of patients based on their IBS type, diarrhea-predominant patients showed a positive response to the probiotic improving their sleep (p=0.05 and 0.03 at weeks 2 and 6, respectively). Patients with constipation-predominant IBS showed no response to the probiotic; while patients with diarrhea-constipation mixed IBS showed unfavorable response to the probiotic in the need for strain to pass a motion compared to the placebo (p=0.03 and 0.02 at weeks 4 and 6, respectively)

Vectors of Crimean Congo Hemorrhagic Fever virus in Iran

Background: Ticks are important vectors and reservoirs of Crimean Congo Hemorrhagic Fever (CCHF) virus. Human beings may be infected whenever the normal life cycle of the infected ticks on non- human vertebrate hosts is interrupted by the undesirable presence of humans in the cycle. A total of 26 species of Argasid and Ixodid ticks have been recorded in Iran; including nine Hyalomma, two Rhipicephalus, two Dermacentor, five Haemaphysalis, two Boophilus, one Ixodes and two Argas as well as three Ornithodoros species as blood sucking ectoparasites of livestock and poultries. The present paper reviews tick vectors of CCHF virus in Iran, focusing on the role of ticks in different provinces of Iran using reverse transcription polymerase chain reaction (RT-PCR) assay. Methods: During ten years study, 1054 tick specimens; including two species of Argasidae and 17 species of Ixodidae were examined for their infection to CCHF virus genome. The output of all studies as well as related publications were discussed in the current paper. Results: The results show that Rhipicephalus sanguineus, Hyalomma marginatum, H. anatolicum, H. asiaticum and H. dromedarii were known as the most frequent species which were positive for CCHF virus. Conclusion: The status of ticks which were positive for CCHF virus revealed that unlike the most common idea that Hyalomma species are the most important vectors of CCHF virus, other ticks including Rhipicephalus, Haemaphysalis and Dermacentor can be reservoir of this virus; thus, considering geographical distribution, type of host and environmental conditions, different tick control measurements should be carried out in areas with high incidence of CCHF disease