Dopamine agonist serum concentrations and impulse control disorders in Parkinson's disease

Background and purpose: Impulse control disorders (ICDs) are common among Parkinson's disease patients using dopamine agonists. We wanted to determine whether ICD patients have higher dopamine agonist serum concentrations than those without any sign of ICD. Methods: Patients who used either pramipexole or ropinirole depot once daily were screened for ICDs using the validated Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease–Rating Scale. Those who scored above the cut-off for one or more of the four defined ICDs (gambling, compulsive sexual behavior, compulsive shopping, and binge-eating) were compared in a case–control study to patients who scored zero points (no evidence of ICD) on the same items. They were examined clinically and evaluated using relevant scales. Three blood samples were taken on the same day: before daily dose, and then 6 and 12 h later. Results: Forty-six patients were included: 19 ICD-positive and 27 controls. Ropinirole serum concentrations 6 h after daily intake (Cmax) were higher in the case group compared to the control group, as was the daily ropinirole dosage. No differences were observed in serum concentrations, dosage or total drug exposure for pramipexole. Disease duration and length of dopamine agonist treatment was significantly longer among ICD patients for ropinirole, but not for pramipexole. Conclusions: The use of pramipexole may in itself confer high ICD risk, whereas ICDs among ropinirole users depend more on serum concentration and drug exposure. The pharmacokinetic properties of ropinirole make it challenging to predict its effects on patients, which supports the need for therapeutic drug monitoring to reduce risk of ICD

A procedure for determining long-term creep rates of soft clays by triaxial testing

The paper presents a procedure for determining a significantly larger range of creep rates (isotaches) of soft clays than found from standard incremental loading oedometer tests. The test is performed in a triaxial apparatus by first loading up to the virgin compression line at a relevant effective stress level and then determine the creep rates at different stress states along an unloading branch keeping the horizontal to vertical effective stress ratio constant. The test procedure is tested on a soft Norwegian plastic marine clay. Challenges due to the non-linear behaviour of natural soft clays where the standard creep and compression indexes are not constant values are demonstrated, and recommendations for how to account for this effect are given. The obtained results from the test are also compared with results from a parallel long-term creep phase in a standard oedometer apparatus taken from the same block sample

Design considerations of suction caisson foundations for offshore wind turbines in Southern China

Suction caisson foundations are increasingly considered as a foundation solution for offshore wind farm development in China. This paper outlines the design considerations for developing a suction caisson supported jacket solution for an offshore wind farm in Southern China. Geotechnical analyses for four major aspects, ultimate limit state (ULS), serviceability limit state (SLS), fatigue limit state (FLS) and installation are discussed. The design challenges encountered in the project due to soft seabed and metocean characteristics (severe typhoon loading and dominant wind directions) and technical approaches adopted by the project are presented. Areas for further studies are identified and discussed. The purpose of this paper is to disseminate this knowledge and raise awareness of several important aspects.publishedVersio

Micro-level investigation of the in situ shear vane failure geometry in sensitive clay

The circumferential failure surface of a shear vane in strain softening soft sensitive clay is studied. A set of shear vane experiments are performed in situ, where the sheared region is retrieved from the ground using an over-coring technique. By producing thin sections, the circumferential failure zone is revealed when viewed under a polarised light microscope. The failure zone is found to first evolve after reaching the peak global resistance. Its shape is not a full cylinder, but rather a rounded square. The structure of the shear zone is non-smooth and characterised by complex shear patterns of micrometre size

Time- and stress-compressibility of clays during primary consolidation

The existence of creep deformation during primary consolidation has been widely accepted; however, there are still contradicting opinions on the mechanisms that govern creep during the primary consolidation phase. This study aims to assess creep effects during primary consolidation such that it is possible to critically evaluate and challenge some of these opinions. A special type of interconnected oedometer tests were designed and conducted. The tests were numerically studied using a soil model based on the isotache concept. These analyses show that the isotache concept can capture the important features of the tests well and thereby describe the time- and stress-compressibility of a soil during the entire soil compression phase

Time- and stress-compressibility of clays during primary consolidation

The existence of creep deformation during primary consolidation has been widely accepted; however, there are still contradicting opinions on the mechanisms that govern creep during the primary consolidation phase. This study aims to assess creep effects during primary consolidation such that it is possible to critically evaluate and challenge some of these opinions. A special type of interconnected oedometer tests were designed and conducted. The tests were numerically studied using a soil model based on the isotache concept. These analyses show that the isotache concept can capture the important features of the tests well and thereby describe the time- and stress-compressibility of a soil during the entire soil compression phase