Evaluation of Liquefaction Potential of an Earth Dam Foundation Using In Situ Tests

This paper presents a case study of liquefaction potential assessment carried out under an earth dam foundation in Tunisia. An emphasis was made on the exploration of geotechnical conditions and the interpretation of field tests results collected before and after soil densification using the vibrocompaction technique. The assessment of soil liquefaction susceptibility was made using deterministic and probabilistic simplified procedures developed from several case histories. Conclusively, the obtained results show that before vibrocompaction the soil was prone to the liquefaction hazard. However, after vibrocompaction, a significant improvement of the soil resistance reduces the liquefaction potential of the sandy foundation. Indeed, before vibrocompaction, the factor of safety (FS) drops below 1 which means that the soil is susceptible for liquefaction. However, after vibrocompaction, the values of FS exceed the unit which justify the absence of liquefaction hazard in the dam foundation. In addition, before soil densification, the liquefaction evaluation using CPT-data shows probabilities values over 65 % which correspond to the classes of ‘’very likely’’ and ‘’Almost certain that will be liquefy’’ in the field case histories classification. The treated site presents low probability of liquefaction (less than 35%) indicating a low likelihood of liquefaction of the dam foundation

The yeast ubiquitin ligase SCF(Met30): connecting environmental and intracellular conditions to cell division

Ubiquitination regulates a host of cellular processes and is well known for its role in progression through the cell division cycle. In budding yeast, cadmium and arsenic stress, the availability of sulfur containing amino acids, and the intracellular concentration of S-adenosylmethionine are linked to cell cycle regulation through the ubiquitin ligase SCF(Met30). Regulation is achieved by ubiquitination of the transcription factor Met4. Met4 activity is controlled by a regulatory K48-linked ubiquitin chain that is synthesized by Cdc34/SCF(Met30). A ubiquitin-interacting-motif (UIM) present in Met4 prevents degradation of ubiquitinated Met4 allowing the ubiquitin chain to function as a reversible switch of Met4 activity. Here we discuss mechanisms of Met4 and SCF(Met30 )regulation in response to intracellular and environmental conditions, and describe the integration of these signals with cell cycle control

Chemical genetics screen for enhancers of rapamycin identifies a specific inhibitor of an SCF family E3 ubiquitin ligase

The target of rapamycin (TOR) plays a central role in eukaryotic cell growth control. With prevalent hyperactivation of the mammalian TOR (mTOR) pathway in human cancers, strategies to enhance TOR pathway inhibition are needed. We used a yeast-based screen to identify small-molecule enhancers of rapamycin (SMERs) and discovered an inhibitor (SMER3) of the Skp1-Cullin-F-box (SCF)^(Met30) ubiquitin ligase, a member of the SCF E3-ligase family, which regulates diverse cellular processes including transcription, cell-cycle control and immune response. We show here that SMER3 inhibits SCF^(Met30) in vivo and in vitro, but not the closely related SCF^(Cdc4). Furthermore, we demonstrate that SMER3 diminishes binding of the F-box subunit Met30 to the SCF core complex in vivo and show evidence for SMER3 directly binding to Met30. Our results show that there is no fundamental barrier to obtaining specific inhibitors to modulate function of individual SCF complexes

Ubiquitin and transcription: The SCFMet30/Met4 pathway, a (protein-) complex issue

Ubiquitylation has emerged as an omnipresent factor at all levels of transcriptional regulation. A recent study that describes the yeast transcriptional activator Met4 as a functional component of the very same ubiquitin ligase that regulates its own activity highlights the close relation between transcription and the ubiquitin proteasome system

: EVALUATION OF LIQUEFACTION RISK OF AN EARTH DAM FOUNDATIONUSING IN SITU TESTS

National audienceLa liquéfaction des sols est un risque majeur pour les ouvrages construits ou fondés sur desterrains sableux et saturés. L’étude proposée s’inscrit dans cette catégorie. Elle est appliquée à lafondation d’un barrage en terre dont le sol est formé essentiellement de couches de sablessaturées. L’ouvrage étant situé dans une zone sismique, il convient donc de s’intéresser aucomportement des sols de la fondation du barrage vis-à-vis du risque de liquéfaction. Ce risqueétait d’ailleurs à l’origine d’une opération de traitement de la fondation par vibrocompactage. Leprésent article vise à évaluer le potentiel de liquéfaction de la fondation du barrage. Le travailporte sur l’exploitation des résultats des essais SPT (Standard Penetration Test) et CPT (ConePenetration Test) effectués avant et après densification du sol par vibrocompactage. Lesrésultats obtenus ont permis de confirmer l’efficacité du vibrocompactage. Cette étude peutservir de base à d’autres analyses effectuées dans les mêmes conditions

Verifying liquefaction remediation beneath an earth dam using SPT and CPT based methods

AbstractThis paper presents a case study of liquefaction potential assessment for the foundation of an earth dam in Tunisia. An emphasis was made on the exploration of geotechnical conditions and the interpretation of field tests (SPT and CPT) and the results were collected before and after soil densification using the vibrocompaction technique. The assessment of soil liquefaction triggering was made using deterministic and probabilistic simplified procedures. The results indicate that before vibrocompaction the studied area was prone to the liquefaction hazard. However, after vibrocompaction a significant improvement of the soil resistance reduced the liquefaction potential of the sandy foundation soil. The SPT resistance values increased on average from 12 to 25 blow counts/0.3m, and the CPT resistance increased on average from 8MPa to 14MPa. Before vibrocompaction, the factor of safety (FS) against liquefaction fell below 1.0, which means that the soil is susceptible for liquefaction. After vibrocompaction the values of FS exceed the unit which justified the liquefaction mitigation efforts in dam foundation

The yeast ubiquitin ligase SCFMet30: connecting environmental and intracellular conditions to cell division

Ubiquitination regulates a host of cellular processes and is well known for its role in progression through the cell division cycle. In budding yeast, cadmium and arsenic stress, the availability of sulfur containing amino acids, and the intracellular concentration of S-adenosylmethionine are linked to cell cycle regulation through the ubiquitin ligase SCFMet30. Regulation is achieved by ubiquitination of the transcription factor Met4. Met4 activity is controlled by a regulatory K48-linked ubiquitin chain that is synthesized by Cdc34/SCFMet30. A ubiquitin-interacting-motif (UIM) present in Met4 prevents degradation of ubiquitinated Met4 allowing the ubiquitin chain to function as a reversible switch of Met4 activity. Here we discuss mechanisms of Met4 and SCFMet30 regulation in response to intracellular and environmental conditions, and describe the integration of these signals with cell cycle control