S. Johansson

Bio: S. Johansson is an academic researcher from Swedish University of Agricultural Sciences. The author has contributed to research in topics: Internal erosion & Embankment dam. The author has an hindex of 6, co-authored 9 publications receiving 280 citations.

Using the resistivity method for leakage detection in a blind test at the Røssvatn embankment dam test facility in Norway

Abstract: Internal erosion is a cause of embankment dam failure, thus it is important to develop methods for seepage monitoring and internal erosion detection. In order to evaluate the potential of resistivity monitoring to give an early warning of such leakage/erosion, a test was undertaken on a rockfill embankment dam with a central glacial till core at the Rossvatn test facility in Norway. Three defects, consisting of permeable material, were built into the dam at various depths and locations unknown to the personnel carrying out the measurements and data interpretation. A numerical modelling pre-study was carried out, showing that all the actually constructed defects were too small to be detected by single time investigation. In the final test, repeated measurements were undertaken with different reservoir levels, i.e. a limited monitoring approach. This increased the detection capability, confirming the value of the geophysical approach and that monitoring is superior to single time investigations.

Embankment dam seepage evaluation from resistivity monitoring data

Abstract: Methods for monitoring seepage are important for the safety of embankment dams. Increased seepage may be associated with internal erosion in the dam and internal erosion is one of the main reasons for dam failures. Internal erosion progresses inside the dam and is difficult to detect by conventional methods. Therefore there is a need for new or improved methods. The resistivity method is a non-destructive method that may accomplish this task. It has been tried in an on-going research programme in Sweden. Daily resistivity measurements are carried out on permanent installations on two Swedish embankment dams. In this paper the installations on the Sadva embankment dam are described and selected parts of the results are presented. In addition, a method for evaluating the seepage from resistivity monitoring data is theoretically described and tested for four selected areas in the foundation of the Sadva dam. Seasonal resistivity variations are apparent in the reservoir as well as inside the dam. Most parts of the dam have a homogeneous resistivity distribution with consistent variations. The overall status of the dam is satisfactory. However part of the foundation demonstrates a slightly different behaviour pattern with regard to the seasonal variation. The four selected areas represent localities with low, intermediate and high variations in seasonal resistivity. The areas are compared qualitatively and thereby permeable zones within the dam may be identified. Quantitative assessment of the seepage flow is also carried out as an initial test of the described method. It is concluded that the experiences from the Sadva dam are valuable with regard to the use of the resistivity method on embankment dams. Resistivity monitoring data may be used to qualitatively assess the seepage through the dam. For quantitative assessment, the method is promising and the data from the Sadva dam constitute an interesting initial approach. However, many assumptions and simplifications are made and more work on refining the method is needed.

Serum IgE reactivity to Malassezia furfur extract and recombinant M. furfur allergens in patients with atopic dermatitis.

Abstract: IgE reactivity to the opportunistic yeast Malassezia furfur can be found in patients with atopic dermatitis (AD). We have previously cloned and expressed 6 recombinant allergens (rMal f 1, rMal f 5-9) from M. furfur. In the present study, we used ImmunoCAP to investigate whether these rMal f allergens can be useful in the diagnosis of M. furfur-associated AD compared with the M. furfur extract. A total of 156 adult patients with a clinical diagnosis of AD participated in the study. Sixty-four percent had increased total serum IgE levels, 79% had specific IgE antibodies to common inhalant allergens and 47% had IgE antibodies to M. furfur extract. IgE antibodies to any of the rMal f allergens were detected among 86 (55%) of the patients, 14 (16%) of whom did not react to the M. furfur extract. Any individual rMal f allergen detected between 32% and 89% of the patients ImmunoCAP-positive to the M. furfur extract, with the highest sensitivity for rMal f 9. Therefore, a couple of individual rMal f allergens can improve the diagnosis of M. furfur-associated IgE allergies in patients with AD.

Observations on normal EEG activity in different brain regions of the unrestrained swine

Abstract: This methodological and electrophysiological study was undertaken with the aim of obtaining possibilities for evaluating objectively the ethical value of using high concentration CO2 inhalation as pre-slaughter anaesthesia for swine. A technique for implantation of recording electrodes into the porcine neocortex and limbic system is described, as are results of EEG recording from these brain regions in the unrestrained animal. In addition to expected desynchronized activity in the awake animal, bilateral recordings from the frontal neocortex revealed the irregular occurrence of 'sleep spindle' during apparent non-REM sleep. The 'spindles' were sometimes unilateral, and when bilaterally simultaneous, the amplitude was often larger in one of the hemispheres. The EEG recorded from the dorsal hippocampus was characterized by theta-wave activity. The offering of food to the hungry animal, and subsequent brief feeding periods, were associated with marked accentuation of this theta activity. Recording via electrodes placed within the amygdaloid nuclear complex showed high-frequency activity irregularly interrupted by slow waves. However, if one of the 'amygdaloid' twin electrodes hit the ventral pole of the hippocampus, theta activity was dominant. Electrodes placed adjacent to the amygdaloid nuclei in the pyriform cortex exhibited a basic awake activity similar to that recorded from these nuclei. During apparent non-REM sleep, however, trains of slow waves were seen simultaneously with the appearance of 'sleep spindles' in the ipsilateral neocortex.

Atopic dermatitis: A practice parameter update 2012

Abstract: This parameter was developed by the Joint Task Force on Practice Parameters, representing the American Academy of Allergy, Asthma & Immunology (AAAAI); the American College of Allergy, Asthma & Immunology (ACAAI); and the Joint Council of Allergy, Asthma and Immunology. The AAAAI and the ACAAI have jointly accepted responsibility for establishing "Atopic dermatitis: a practice parameter update 2012." This is a complete and comprehensive document at the current time. The medical environment is a changing environment, and not all recommendations will be appropriate for all patients. Because this document incorporated the efforts of many participants, no single individual, including those who served on the Joint Task Force, is authorized to provide an official AAAAI or ACAAI interpretation of these practice parameters. Any request for information about or an interpretation of these practice parameters by the AAAAI or ACAAI should be directed to the Executive Offices of the AAAAI, the ACAAI, and the Joint Council of Allergy, Asthma & Immunology. These parameters are not designed for use by pharmaceutical companies in drug promotion. Published practice parameters of the Joint Task Force on Practice Parameters for Allergy & Immunology are available online at http://www.jcaai.org.

The clinical use of stress echocardiography in non-ischaemic heart disease: recommendations from the European Association of Cardiovascular Imaging and the American Society of Echocardiography.

Abstract: A unique and highly versatile technique, stress echocardiography (SE) is increasingly recognized for its utility in the evaluation of non-ischaemic heart disease. SE allows for simultaneous assessment of myocardial function and haemodynamics under physiological or pharmacological conditions. Due to its diagnostic and prognostic value, SE has become widely implemented to assess various conditions other than ischaemic heart disease. It has thus become essential to establish guidance for its applications and performance in the area of non-ischaemic heart disease. This paper summarizes these recommendations.