Biomedical subjects

G Olsson

Publications and source records attributed to G Olsson.

At least 19 recordsLinked to original sources

PubMed2006

Plant-wide control: dream, necessity or reality?

Instrumentation, control and automation (ICA) are key technologies in modern water and wastewater systems. Despite the variability of the influents the system outputs have to be satisfactory. Economic realities and new water directives encourage the application of ICA to make a maximum use of plant and other storage capacities. The final goal of protecting the environmental resources necessitates an integrated view of several interdependent systems, including the collection, transport and treatment processes. In this integrating development ICA will be a decisive technology.

Automation↗

PubMed2006

Instrumentation, control and automation in the water industry--state-of-the-art and new challenges.

Instrumentation, control and automation (ICA) are key technologies in modern water and wastewater systems. Ever present disturbances make it necessary to automatically attenuate their consequences. A wastewater treatment system is load driven, while a water distribution system is demand driven. Despite the variability the system outputs have to be satisfactory. Economic realities encourages the application of ICA to make a maximum use of plant capacities. An increasing complexity of competing processes in a modern nutrient removal plant makes more elaborate control necessary. The final goal of protecting the environmental resources necessitates an integrated view of several interdependent systems, the collection, transport and treatment processes. In this integrating development ICA will be a decisive technology.

Automation↗

PubMed2006

Extremum-seeking with variable gain control for intensifying biogas production in anaerobic fermentation.

A state-dependent variable-gain control system is implemented to follow the characteristics of a laboratory-scale up-flow anaerobic fixed-bed reactor dynamically. The transition from one state to another is determined on an hourly basis, depending on difference between the setpoint of the reactor pH and its true value. Considerable improvement of the process stability--reduction of oscillation in both the reactor pH and biogas production rate during high-rate operation, has been achieved, although the control structure is simple and intuitive.

Algorithms↗

PubMed2006

Failure monitoring in water distribution networks.

An algorithm for the burst detection and location in water distribution networks based on the continuous monitoring of the flow rate at the entry point of the network and the pressure at a number of points within the network is presented. The approach is designed for medium to large bursts with opening times in the order of a few minutes and is suitable for networks of relatively small size, such as district metered areas (DMAs). The burst-induced increase in the inlet flow rate is detected using the modified cumulative sum (CUSUM) change detection test. Based on parameters obtained from the CUSUM test, the burst is simulated at a number of burst candidate locations. The calculated changes in pressure at the pressure monitoring points are then compared to the measured values and the location resulting in the best fit is selected as the burst location. The EPANET steady-state hydraulic solver is utilised to simulate the flows and pressures in the network. A sensitivity-based sampling design procedure is introduced to find the optimal positions for pressure monitoring points. The proposed algorithm is tested on a case study example network and shows potential for burst detection and location in real water distribution systems.

Algorithms↗

PubMed2006

Quality of life following liposuction and conservative treatment of arm lymphedema.

Arm lymphedema can produce an additional burden from a psychosocial point of view. Although edema reduction through treatment can be an advantage in terms of reduced weight of the arm and simplified clothing needs, the purpose of the present study was to register changes in psychosocial parameters during one year after treatment. Thirty-five patients underwent liposuction combined with postoperative CCT (Controlled Compression Therapy), while 14 received CCT alone. Edema volume and range of motion in the shoulder joint were measured and effects on quality of life were assessed with various questionnaires. Liposuction+CCT removed the arm lymphedema completely, whereas CCT alone reduced it by half. The treatments improved range of motion in the shoulder joint and patients' quality of life in relationship to the volume reduction. Liposuction+CCT improves patients' quality of life, particularly qualities related to the volume reduction and hence qualities associated with everyday activities. CCT is beneficial too, but the effect is less obvious than when combined with surgery, probably because the edema reduction is less. The consequences of arm lymphedema for more psychologically oriented qualities and social life in general seem to be less serious and we found few notable effects of treatment in these domains.

Aged↗

PubMed2005

A benchmark study of controlled emptying of equalization basins.

Storm tanks, or equalization basins, have been used for many years in sewer or wastewater treatment systems to reduce the amount of combined sewer overflows. In this paper, a systematic control of an equalization basin is used not only to dampen or reduce the hydraulic load, but also to systematically improve the effluent quality in a nitrogen removal plant. It is demonstrated that the effluent ammonia concentration is the key component. The Benchmark Simulation Model 1, implemented in MATLAB/Simulink, has been used to perform the evaluations. It has been extended with systematic rainfall generations. Intuitively, it is apparent that the equalization basin should be emptied before a rainfall. This requires a prediction capacity. It is shown that the choice of prediction time is by no means trivial and it is not true that a long prediction horizon is always advantageous.

Computer Simulation↗

PubMed2004

Induction of homologous recombination in the hprt gene of V79 Chinese hamster cells in response to low- and high-LET irradiation.

Dense ionization tracks from high linear energy transfer (LET) radiations form multiple damaged sites (MDS), which involve several types of DNA lesions in close vicinity. The primary DNA damage triggers sensor proteins that activate repair processes, cell cycle control or eventually apoptosis in subsequent cellular responses. The question how homologous recombination (HR) and non-homologous end joining (NHEJ) interact in the repair of radiation-induced DNA damage of MDS type has been addressed in different model systems but several questions remain to be answered. We have therefore challenged cells with treatments of ionizing radiation of different qualities to investigate whether primary DNA damages of different complexity are reflected in the processes of repair by HR as well as cell survival. We used the V79 derived SPD8 cell line to determine the induction of HR in the hprt exon 7 and clonogenic assay for survival in response to radiation. SPD8 cells were irradiated with gamma-rays (137Cs 0.5 keV/microm), boron ions (40 and 80 keV/microm) and nitrogen ions (140 keV/microm), with doses up to 5 Gy. Analysis of clonogenic survival showed that B-ions (80 keV/microm) and N-ions were more toxic than gamma-rays, 4.1 and 5.0 times respectively, while B-ions at 40 keV/microm were 2.0 times as toxic as gamma-rays. Homologous recombination in the cells exposed to B-ions (80 keV/microm) increased 2.9 times, a significant response as compared to cells exposed to gamma-rays, while for B-ions (40 keV/microm) and N-ions a nonsignificant increase in HR of 1.2 and 1.4, respectively, was observed. We hypothesize that the high-LET generated formation of MDS is responsible for the enhanced cytotoxicity as well as for the mobilization of the HR machinery.

Animals↗

PubMed2004

Control of an anaerobic reactor towards maximum biogas production.

A new control strategy is introduced for operating anaerobic digestion processes efficiently at high load. The control system includes a cascade controller embedded into a rule-based supervisory system based on extremum-seeking control. The control system measures pH and biogas production rate and varies the organic load by manipulating the influent flow. Good control performances were achieved during the start-up and steady-state running operations and during rejection of disturbances. The control system can run the process under a high load condition and efficiently reject disturbances without explicit measurement of the influent characteristics.

Algorithms↗

PubMed2003

Application of information technology to decision support in treatment plant operation.

This paper reviews decision support methodologies that can be applied to treatment plants. Case studies of decision support systems (DSS) that have been developed and used or trialled are presented below. These include rule-based systems and systems based on digraphs of cause-and-effect relationships. Detection examples on real plant data are presented, in one case using direct measurements and simple detectors and in another using multivariate statistics and clustering.

Decision Support Techniques↗

PubMed2002

Lessons learnt at ICA2001. IWA Conference on Instrumentation, Control and Automation.

This paper gives an introduction as well as some general experiences and conclusions from the 1st IWA Conference on Instrumentation, Control and Automation (ICA2001), June 3-7, 2001, Malmö, Sweden. The highlights from the different sessions of the conference are summarised and some challenges for the coming years, with regard to ICA within the field of wastewater treatment, are also discussed.

Automation↗

PubMed2002

A hedging point strategy--balancing effluent quality, economy and robustness in the control of wastewater treatment plants.

An operational space map is an efficient tool to compare a large number of operational strategies to find an optimal choice of setpoints based on a multicriterion. Typically, such a multicriterion includes a weighted sum of cost of operation and effluent quality. Due to the relative high cost of aeration such a definition of optimality result in a relatively high fraction of the effluent total nitrogen in the form of ammonium. Such a strategy may however introduce a risk into operation because a low degree of ammonium removal leads to a low amount of nitrifiers. This in turn leads to a reduced ability to reject event disturbances, such as large variations in the ammonium load, drop in temperature, the presence of toxic/inhibitory compounds in the influent etc. Hedging is a risk minimisation tool, with the aim to "reduce one's risk of loss on a bet or speculation by compensating transactions on the other side" (The Concise Oxford Dictionary (1995)). In wastewater treatment plant operation hedging can be applied by choosing a higher level of ammonium removal to increase the amount of nitrifiers. This is a sensible way to introduce disturbance rejection ability into the multi criterion. In practice, this is done by deciding upon an internal effluent ammonium criterion. In some countries such as Germany, a separate criterion already applies to the level of ammonium in the effluent. However, in most countries the effluent criterion applies to total nitrogen only. In these cases, an internal effluent ammonium criterion should be selected in order to secure proper disturbance rejection ability.

Automation↗

PubMed2002

Dissolved oxygen controller based on on-line measurements of ammonium combining feed-forward and feedback.

As the largest single energy-consuming component in most biological wastewater treatment systems, control of aeration is of great interest seen from an energy savings point of view. This paper suggests a simple way of using on-line ammonium measurements to control aeration in a pre-denitrification plant by controlling the dissolved oxygen setpoint. The controller works primarily by feed-forward based on an ammonium sensor located at the head of the aerobic process part. Using online in-situ sensor measurements directly from the process have the important advantage over effluent measurements that there is no or very short time delay for information. The controller has been implemented in a full-scale wastewater treatment plant for a period of 35 days. During the experiment two identical activated sludge lines were used. The controller was implemented in one line, while the other line worked as a reference for comparison. The preliminary results indicate that the described control strategy leads to energy savings for the aeration in the region of 5-15%, while maintaining approximately the same effluent quality as in the reference line. Even higher energy savings can probably be achieved by optimising the controller. An automatic procedure for updating the controller parameters based on dynamic effluent ammonium measurement has been tested.

Algorithms↗

PubMed2002

Exploiting online in-situ ammonium, nitrate and phosphate sensors in full-scale wastewater plant operation.

In-situ nutrient sensors are now a proven technology. Having ion membranes eliminates the need for ultrafiltration, and consequently the sensors can be located at suitable places in any of the reactors. This gives the potential for new control structures for the control of nitrification, denitrification, and phosphorus removal. In the paper some examples of such controllers are demonstrated as used in a full-scale wastewater treatment plant. A successful control implementation scheme at full-scale plants includes three steps: monitoring, experimenting and controlling. The benefit of implementing process control based on nutrient sensors is real: by implementing precipitation dosage control a savings of 41% compared to flow proportional dosage can be reached, while the savings compared to constant dosage is 73%. An increase in nitrate recirculation shows significant improvement in the nitrogen removal ability at very low cost. Reliable nutrient sensors are not the only prerequisite for a successful control system. The design of actuators, such as drives, compressors and valves, is often overlooked. Furthermore, the lower level controllers have to work properly before the more advanced controllers can work adequately. A collection of practical experience regarding such issues is given in this paper.

Automation↗

PubMed2001

ELF magnetic field affects proliferation of SPD8/V79 Chinese hamster cells but does not interact with intrachromosomal recombination.

Extremely low-frequency (ELF) magnetic fields have previously been shown to affect conformation of chromatin, cell proliferation, and calcium metabolism. Possible mutagenic and carcinogenic effects of ELF have also been discussed and tested. In this study, intrachromosomal recombination in the hprt gene after exposure to ELF magnetic field was investigated using the SPD8 recombination assay. SPD8 cells, derived from V79 Chinese hamster cells were exposed to ELF at a specific combination of static and ELF magnetic fields, that has been proven to have effects on chromatin conformation in several cell types. The genotoxic agent camptothecin (CPT) was used either as a positive control or simultaneously with ELF. We also analysed the effect of ELF and CPT on chromatin conformation with the anomalous viscosity time dependence (AVTD) technique, cell growth kinetics, and cell survival with clonogenic assay. DNA fragmentation was analysed by pulsed field gel electrophoresis (PFGE). ELF did not induce recombination alone, neither did ELF modify the recombinogenic effect of CPT. Although, there was no effect on cell survival in response to ELF exposure, inhibition of cell growth was observed. On the other hand, ELF exposure partly counteracted the growth inhibition seen with CPT. The data suggest that ELF exposure may stimulate or inhibit cell growth depending on the state of the cells. Although, ELF did not induce recombination, a weak but statistically significant DNA fragmentation comparable with CPT-induced fragmentation was observed with PFGE 48h after exposure to ELF.

Animals↗

PubMed2001

Effect of local cold provocation on systolic blood pressure and skin blood flow in the finger.

Demonstration of increased vascular cold reactivity in patients with Raynaud's syndrome is difficult. For medico-legal reasons, it is important to get objective measures of vasospasm in these patients. Evaluation of the degree of vasospasm also provides prognostic information which is useful for patient management. In this study, we compare two methods of arterial circulation measurement. The laser Doppler scanning is a new method, which uses the recently developed laser Doppler perfusion imaging (LDPI) instrument. The aim of the present study was to compare the effect on finger skin blood flow measured with LDPI with changes in finger systolic blood pressure during local cold provocation. The effect of such provocation, skin blood flow and systolic blood pressure, were studied in 15 healthy controls. Six patients with known traumatic vasospastic disease (TVD) were also tested with both methods. Finger skin blood flow was measured with LDPI on the distal phalanx of the index finger of the left hand, every minutes during 6 min of local heating at 40 degrees C followed by local cooling for 3 min at 15 degrees C and then for 3 min at 10 degrees C. Finger systolic blood pressure was measured with strain-gauge method before and after local cooling to 10 degrees C with a cuff perfused with water of desired temperature. The test was performed in the same finger within a week of the laser Doppler scanning. Local finger cooling to 15 degrees C and 10 degrees C caused a significant decrease in blood flow, most marked at 10 degrees C. There was, however, no correlation between the decrease in blood flow and blood pressure. In the TVD-patients decreases in skin blood flow were similar compared with the healthy controls. In contrast, the changes in systolic blood pressure, were outside normal range (systolic quotient <0.65) in five of the six patients (83%), and also in 11 of the 15 healthy controls (73%). In conclusion, there is no correlation between the decrease in finger skin blood flow and systolic blood pressure during local cold provocation. For diagnosis of traumatic vasospastic disease (TVD), local cold-induced changes in finger systolic blood pressure seems superior to changes in skin blood flow, but the ideal clinical method for demonstrating increased cold-induced vasospasm is, however, still lacking.

Adult↗

PubMed2001

Enantioselective analysis of citalopram and metabolites in adolescents.

Studies of the antidepressant effect and pharmacokinetics of citalopram have been performed in adults, but the effects on children and adolescents have only been studied to a minor extent despite its increasing use in these age groups. The aim of this study was to investigate a group of adolescents treated for depression, with respect to the steady-state plasma concentrations of the enantiomers of citalopram and its demethylated metabolites desmethylcitalopram and didesmethylcitalopram. Moreover, the authors studied the genotypes for the polymorphic cytochrome P450 enzymes CYP2D6 and CYP2C19 in relation to the different enantiomers. The S/R ratios of citalopram and desmethylcitalopram found in this study of 19 adolescents were similar to studies involving older patients. The concentrations of the R-(-)- and S-(+)-enantiomers of citalopram and desmethylcitalopram were also in agreement with values from earlier studies, the R-(-)-enantiomer (distomer) being the major enantiomer. The results indicate that the use of oral contraceptives may have some influence on the metabolism of citalopram. This might be because of an interaction of the contraceptive hormones with the CYP2C19 enzyme.

Adolescent↗

PubMed2001

The struggle for a cleaner urban environment: water pollution in Malmö 1850-1911.

This article focuses on the emergence of water pollution problems in the city of Malmö and on how they were discussed and solved. Various countermeasures were proposed and considered, but finally the discharge of wastewater into the Sound of Oresund was regarded as the best solution. As a result, a local pollution problem was transformed into a regional issue. The solutions adopted in Malmö are briefly compared with decisions made in Gothenburg and Stockholm.

Cities↗

PubMed2000

Tamoxifen-induced cell death in malignant melanoma cells: possible involvement of the insulin-like growth factor-1 (IGF-1) pathway.

Recent data indicate that the estrogen receptor (ER) blocker tamoxifen (TAM) can induce cell death in malignant melanoma cells. However, as shown in the present study and several other studies melanoma cells usually do not express classical ERs. In the present study we investigated whether the cytotoxic effect of TAM on melanoma cells could depend on interference with the expression or function of the insulin-like growth factor-1 receptor (IGF-1R), a plasma membrane receptor important for cell survival in this tumor cell type. Several melanoma cell lines were included in the analysis. Administration of TAM at a concentration of 15 microm or more resulted in cell death of the melanoma cells within 48 h. TAM treatment was correlated to a slight to moderate inhibition of IGF-1 binding to IGF-1R. Since it has been reported that TAM can increase the release of IGF binding proteins (IGFBPs) we then investigated whether this mechanism could underly the decreased IGF-1 binding. However, we could demonstrate that the amount of released IGFBPs were unchanged or decreased in TAM-treated cells. Whereas TAM did not have any strong effect on IGF-1 binding and the expression of IGF-1R at the cell surface, it was was found to efficently block tyrosine phosphorylation of IGF-1R beta-subunit. Taken together, our data suggest that TAM-induced cytotoxicity of malignant melanoma cells can be due to inactivation of IGF-1R.

Antineoplastic Agents, Hormonal↗