| 1. |
- Benazzi, F, et al.
(författare)
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On an application of extended Kalman filtering to activated sludge processes: A benchmark study
- 2005
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Konferensbidrag (refereegranskat)abstract
- The growing demand for performance improvements of urban wastewater system operation coupled with the lack of instrumentation in most wastewater treatment plants motivates the need for non-linear observers to be used as virtual sensors for estimation and control of effluent quality. This paper is focused on the development of a general procedure for on-line monitoring of activated sludge processes, using an extended Kalman filter (EKF) approach. The Activated Sludge Model no.1 (ASM1) is selected to describe the biological processes in the reactor. On-line measurements are corrupted by additive white noise and unknown inputs are modelled using fast Fourier transform (FFT) and spectrum analyses. The given procedure aims at reducing the original ASM1 model to an observable and identifiable model, which can be used for joint non-linear state and parameter estimations. Simulation results are presented to demonstrate the effectiveness of the proposed methods and show that on-line monitoring of SND and XND concentrations is achieved when dynamic input data are used to characterize the influent wastewater for the model.
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| 2. |
- Benazzi, F, et al.
(författare)
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On-line estimation and detection of abnormal substrate concentrations in WWTPs using a software sensor: A benchmark study
- 2007
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Ingår i: Environmental Technology. - 1479-487X. ; 28:8, s. 871-882
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a new approach for on-line monitoring and detection of abnormal readily biodegradable substrate (SS) and slowly biodegradable substrate (XS) concentrations, for example due to input of toxic loads from the sewer, or due to influent substrate shock load, is proposed. Considering that measurements of SS and XS concentrations are not available in real wastewater treatment plants, the SS | XS software sensor can activate an alarm with a response time of about 60 and 90 minutes, respectively, based on the dissolved oxygen measurement. The software sensor implementation is based on an extended Kalman filter observer and disturbances are modelled using fast Fourier transform and spectrum analyses. Three case studies are described. The first one illustrates the fast and accurate convergence of the extended Kalman filter algorithm, which is achieved in less than 2 hours. Furthermore, the difficulties of estimating XS when off-line analysis is not available are depicted, and the SS | XS software sensor performances when no measurements of SS and XS are available are illustrated. Estimation problems related to the death-regeneration concept of the activated sludge model no.1 and possible application of the software sensor in wastewater monitoring are discussed.
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| 3. |
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| 4. |
- Bengtsson, Oskar, et al.
(författare)
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Identification of common traits in improved xylose-growing Saccharomyces cerevisiae for inverse metabolic engineering.
- 2008
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Ingår i: Yeast. - : Wiley. - 1097-0061 .- 0749-503X. ; 25:11, s. 835-847
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Tidskriftsartikel (refereegranskat)abstract
- Four recombinant Saccharomyces cerevisiae strains with enhanced xylose growth (TMB3400, C1, C5 and BH42) were compared with two control strains (TMB3399, TMB3001) through genome-wide transcription analysis in order to identify novel targets for inverse metabolic engineering. A subset of 13 genes with changed expression levels in all improved strains was selected for further analysis. Thirteen validation strains and two reference strains were constructed to investigate the effect of overexpressing or deleting these genes in xylose-utilizing S. cerevisiae. Improved aerobic growth rates on xylose were observed in five cases. The strains overexpressing SOL3 and TAL1 grew 19% and 24% faster than their reference strain, and the strains carrying deletions of YLR042C, MNI1 or RPA49 grew 173%, 62% and 90% faster than their reference strain.
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| 6. |
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| 7. |
- Dahlman, S., et al.
(författare)
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Expanding the donor pool: lung transplantation with donors 55 years and older
- 2006
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Ingår i: Transplant Proc. - 0041-1345. ; 38:8, s. 2691-3
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Tidskriftsartikel (refereegranskat)abstract
- The scarcity of donor organs is one of the major limitations to lung transplantation. This has led to a progressive expansion of criteria for donor selection in lung transplantation. This study evaluated the outcome of recipients of lungs from donors >/=55 years. We performed a retrospective analysis of 212 consecutive lung transplantations. Recipients were divided into two groups, those receiving lungs from donors >/=55 years (older donor group) and those receiving lungs from donors <55 years (younger donor group). Recipient baseline characteristics, time in the intensive care unit (ICU), early mortality, and long-term survival (Kaplan-Meier) were compared between the groups. Forty-one donors (19%) were >/=55 years. Mean recipient age in the older donor group was higher than in the younger donor group (52 +/- 8 vs. 47 +/- 12 years; P = .015). Indication for transplantation did not differ between the groups. ICU stay was comparable between the two groups (6 +/- 12 vs. 7 +/- 11 days; P = .64). Actual 30-day mortality (10.8% vs. 6.4%; P = .32), 1-year mortality (17.1 vs. 19.6%; P = .50), and cumulative long-term survival (65% and 62% at 5 years, P = 1.00) did not differ between the older and younger donor group. This study indicated that transplantation of lungs from selected donors aged >/=55 years did not impair short-or long-term results. The use of lungs from elderly donors may help to increase the number of donor organs for lung transplantation.
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| 9. |
- Jeppsson, Jan-Olof, et al.
(författare)
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Toward standardization of carbohydrate-deficient transferrin (CDT) measurements: I. Analyte definition and proposal of a candidate reference method.
- 2007
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Ingår i: Clinical Chemistry and Laboratory Medicine. - 1434-6621. ; 45:4, s. 558-562
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Tidskriftsartikel (refereegranskat)abstract
- An alcohol-associated change in the serum transferrin glycoform pattern, carbohydrate-deficient transferrin (CDT), is used as a biomarker of chronic moderate to heavy alcohol consumption. A current limitation in CDT analysis is the lack of standardization, which hampers clinical and analytical comparison between studies. This situation prompted initiation of a Working Group (WG) on CDT Standardization under the auspices of the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). The standardization work aims to define and validate the analyte, select a reference method, work out procedures for the production of reference materials, and make suggestions for the clinical usage of CDT. The first recommendation of the WG is that disialotransferrin should be the primary target molecule for CDT measurement and the single analyte on which CDT standardization is based. It is further recommended that HPLC should be the analytical principle considered as the basis of an interim reference method until a suitable mass spectrometric reference method is established. In clinical use, CDT should be expressed in a relative amount (% CDT), to compensate for variations in the total transferrin concentration.
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| 10. |
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| 11. |
- Johnson, Louis Banka, et al.
(författare)
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Combination of pre-operative radiotherapy and surgery suppresses local accumulation of collagen and TGF-beta 1 in rats
- 2006
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Ingår i: Journal of Surgical Research. - : Elsevier BV. - 1095-8673 .- 0022-4804. ; 133:2, s. 136-142
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Tidskriftsartikel (refereegranskat)abstract
- Background. The systemic and local tissue repair responses of radiation in combination with surgery are still unclear. We have studied the effect of fractionated pre-operative radiotherapy with or without subsequent laparotomy on collagen accumulation using a rodent model. Materials and methods. Thirty-two male Sprague-Dawley rats were divided into four groups (eight rats per group): 1) sham radiation and sham laparotomy (control); 2) sham radiation and laparotomy; 3) radiation and sham laparotomy; and 4) radiation followed by laparotomy. Expanded polytetrafluoroethylene (ePTFE) tubes were implanted subcutaneously in the abdominal wall in the radiotherapy field and on the back outside the radiotherapy field day 0. The abdomen (3 cm x 4 cm) was irradiated day 3 (10 Gy) and again day 7 (10 Gy). On day 10, implants were extirpated, laparotomy undertaken in groups 2 and 4 and new ePTFE tubes implanted subcutaneously. The second implants were extirpated on day 20. Implants were analyzed for hydroxyproline, total protein and transforming growth factor-ss 1 (TGF-ss 1) levels. Results. On day 10, hydroxyproline (P < 0.05) and TGF-ss 1 (P < 0.001) were lower in ePTFE tubes in irra-diated compared with non-irradiated rats. On day 20, the abdominal ePTFE hydroxyproline remained low (P < 0.001) in animals subjected to laparotomy and pre-operative irradiation while hydroxyproline levels of rats subjected to irradiation only were similar to controls. The effects of radiation on hydroxyproline were confined to the irradiated abdominal area. There was a positive correlation between hydroxyproline and TGF-ss 1 levels in the abdominal wall implant day 20 (r = 0.53, P < 0.005). Conclusion. A clinically relevant fractionated radiation scheme reduced subcutaneous collagen accumulation pre-operatively and profoundly within the radiation field post-operatively after laparotomy, possibly because of lowered TGF ss 1 levels. (c) 2006 Elsevier Inc. All rights reserved.
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| 12. |
- Sellgren, A., et al.
(författare)
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The relationship between ASAT, CKMB, Troponin-T and mortality after cardiac surgery
- 2007
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Ingår i: Scand Cardiovasc J. - 1401-7431. ; , s. 1-5
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To investigate the relationship between ASAT, CKMB, Troponin-T and mortality after cardiac surgery. Design. ASAT, CKMB and TnT were analysed in 116 patients. Correlation, sensitivity, specificity and predictive values for permanent myocardial injury (defined as TnT ?2.0 microg/l postoperative day four) were calculated. In the second part our clinical protocol (ASAT on postoperative day 1 and TnT on day 3-4 in patients with ASAT above 2.5 microkat/l) was evaluated. Mortality was compared between patients with ASAT <2.5 microkat/l (ASAT-), 2. ASAT ?2.5 microkat/l and TnT <2.0 microg/l (ASAT+/TnT-) and 3. ASAT ?2.5 microkat/l and TnT ?2.0 microg/l (ASAT+/TnT+). Results. Both ASAT and CKMB had irrespectively of cut-off level, low positive and high negative predictive value of permanent myocardial injury. Early and mid-term mortality did not differ significantly between ASAT- and ASAT+/TnT- patients. Conclusions. ASAT and CKMB can be used to exclude but not to diagnose permanent myocardial injury after cardiac surgery. Increased postoperative ASAT in the absence of increased TnT is not associated with worse clinical outcome than after normal postoperative ASAT.
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