| 1. |
- Martinsson, Johan, et al.
(författare)
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Carbonaceous aerosol source apportionment using the Aethalometer model - evaluation by radiocarbon and levoglucosan analysis at a rural background site in southern Sweden
- 2017
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 17:6, s. 4265-4281
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Tidskriftsartikel (refereegranskat)abstract
- With the present demand on fast and inexpensive aerosol source apportionment methods, the Aethalometer model was evaluated for a full seasonal cycle (June 2014June 2015) at a rural atmospheric measurement station in southern Sweden by using radiocarbon and levoglucosan measurements. By utilizing differences in absorption of UV and IR, the Aethalometer model apportions carbon mass into wood burning (WB) and fossil fuel combustion (FF) aerosol. In this study, a small modification in the model in conjunction with carbon measurements from thermal-optical analysis allowed apportioned non-light-absorbing biogenic aerosol to vary in time. The absorption differences between WB and FF can be quantified by the absorption angstrom ngstrom exponent (AAE). In this study AAE(WB) was set to 1.81 and AAE(FF) to 1.0. Our observations show that the AAE was elevated during winter (1.36 +/- 0.07) compared to summer (1.12 +/- 0.07). Quantified WB aerosol showed good agreement with levoglucosan concentrations, both in terms of correlation (R-2 = 0 : 70) and in comparison to reference emission inventories. WB aerosol showed strong seasonal variation with high concentrations during winter (0.65 mu gm(-3), 56% of total carbon) and low concentrations during summer (0.07 mu gm(-3), 6% of total carbon). FF aerosol showed less seasonal dependence; however, black carbon (BC) FF showed clear diurnal patterns corresponding to traffic rush hour peaks. The presumed non-light-absorbing biogenic carbonaceous aerosol concentration was high during summer (1.04 mu gm(-3), 72% of total carbon) and low during winter (0.13 mu gm(-3), 8% of total carbon). Aethalometer model results were further compared to radiocarbon and levoglucosan source apportionment results. The comparison showed good agreement for apportioned mass of WB and biogenic carbonaceous aerosol, but discrepancies were found for FF aerosol mass. The Aethalometer model overestimated FF aerosol mass by a factor of 1.3 compared to radiocarbon and levoglucosan source apportionment. A performed sensitivity analysis suggests that this discrepancy can be explained by interference of non-light-absorbing biogenic carbon during winter. In summary, the Aethalometer model offers a costeffective yet robust high-time-resolution source apportionment at rural background stations compared to a radiocarbon and levoglucosan alternative.
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| 2. |
- Ahlberg, Daniel, 1982, et al.
(författare)
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Noise sensitivity in continuum percolation
- 2014
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Ingår i: Israel Journal of Mathematics. - : Springer Science and Business Media LLC. - 0021-2172 .- 1565-8511. ; 201:2, s. 847-899
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Tidskriftsartikel (refereegranskat)abstract
- We prove that the Poisson Boolean model, also known as the Gilbert disc model, is noise sensitive at criticality. This is the first such result for a Continuum Percolation model, and the first which involves a percolation model with critical probability pc not equal 1/2. Our proof uses a version of the Benjamini-Kalai-Schramm Theorem for biased product measures. A quantitative version of this result was recently proved by Keller and Kindler. We give a simple deduction of the non-quantitative result from the unbiased version. We also develop a quite general method of approximating Continuum Percolation models by discrete models with pc bounded away from zero; this method is based on an extremal result on non-uniform hypergraphs.
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| 3. |
- Ahlberg, Mats Steinholtz, et al.
(författare)
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Time without PSA recurrence after radical prostatectomy as a predictor of future biochemical recurrence, metastatic disease and prostate cancer death : a prospective Scandinavian cohort study
- 2022
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Ingår i: BMJ Open. - : BMJ Publishing Group Ltd. - 2044-6055. ; 12:12
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Although surveillance after radical prostatectomy routinely includes repeated prostate specific antigen (PSA)-testing for many years, biochemical recurrence often occurs without further clinical progression. We therefore hypothesised that follow-up can be shortened for many patients without increasing the risk of prostate cancer death. We investigated the long-term probabilities of PSA recurrence, metastases and prostate cancer death in patients without biochemical recurrence five and 10 years after radical prostatectomy.Design: Prospective cohort study. Stratification by Gleason score (<= 3+4=7or >= 4+3=7), pathological tumour stage (pT2 or >= pT3) and negative or positive surgical margins.Setting: Between 1989 and 1998, 14 urological centres in Scandinavia randomised patients to the Scandinavian Prostate Cancer Group study number 4 (SPCG-4) trial.ParticipationAll 306 patients from the SPCG-4 trial who underwent radical prostatectomy within 1year from inclusion were eligible. Four patients were excluded due to surgery-related death (n=1) or salvage radiotherapy or hormonal treatment within 6weeks from surgery (n=3).Primary outcome measures: Cumulative incidences and absolute differences in metastatic disease and prostate cancer death.Results: We analysed 302 patients with complete follow-up during a median of 24 years. Median preoperative PSA was 9.8ng/mL and median age was 65 years. For patients without biochemical recurrence 5 years after radical prostatectomy the 20-year probability of biochemical recurrence was 25% among men with Gleason score <= 3+4=7and 57% among men with Gleason score >= 4+3=7; the probabilities for metastases were 0.8% and 17%; and for prostate cancer death 0.8% and 12%, respectively. The long-term probabilities were higher for pT >= 3versus pT2 and for positive versus negative surgical margins. Limitations include small size of the cohort.Conclusion: Many patients with favourable histopathology without biochemical recurrence 5years after radical prostatectomy could stop follow-up earlier than 10 years after radical prostatectomy.
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| 4. |
- Björklund, Elisabet, et al.
(författare)
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Quality control of flow cytometry data analysis for evaluation of minimal residual disease in bone marrow from acute leukemia patients during treatment.
- 2009
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Ingår i: Journal of pediatric hematology/oncology : official journal of the American Society of Pediatric Hematology/Oncology. - : Lippincott Williams & Wilkins. - 1536-3678 .- 1077-4114. ; 31:6, s. 406-15
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Tidskriftsartikel (refereegranskat)abstract
- Low levels of leukemia cells in the bone marrow, minimal residual disease (MRD), are considered to be a powerful indicator of treatment response in acute lymphatic leukemia (ALL). A Nordic quality assurance program, aimed on standardization of the flow cytometry MRD analysis, has been established before implementation of MRD at cutoff level 10 as one of stratifying parameters in next Nordic Society of Pediatric Hematology and Oncology (NOPHO) treatment program for ALL. In 4 quality control (QC) rounds 15 laboratories determined the MRD levels in 48 follow-up samples from 12 ALL patients treated according to NOPHO 2000. Analysis procedures were standardized. For each QC round a compact disc containing data in list-mode files was sent out and results were submitted to a central laboratory. At cutoff level 10, which will be applied for clinical decisions, laboratories obtained a high concordance (91.6%). If cutoff level 10 was applied, the concordance would be lower (85.3%). The continuing standardization resulted in better concordance in QC3 and QC4 compared with QC1 and QC2. The concordance was higher in precursor B as compared with T-cell ALL. We conclude that after standardization, flow cytometry MRD detection can be reliably applied in international, multicenter treatment protocols.
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| 5. |
- Dods, Robert, 1989, et al.
(författare)
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Ultrafast structural changes within a photosynthetic reaction centre.
- 2021
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 589:7841, s. 310-314
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Tidskriftsartikel (refereegranskat)abstract
- Photosynthetic reaction centres harvest the energy content of sunlight by transporting electrons across an energy-transducing biological membrane. Here we use time-resolved serial femtosecond crystallography1 using an X-ray free-electron laser2 to observe light-induced structural changes in the photosynthetic reaction centre of Blastochloris viridis on a timescale of picoseconds. Structural perturbations first occur at the special pair of chlorophyll molecules of the photosynthetic reaction centre that are photo-oxidized by light. Electron transfer to the menaquinone acceptor on the opposite side of the membrane induces a movement of this cofactor together with lower amplitude protein rearrangements. These observations reveal how proteins use conformational dynamics to stabilize the charge-separation steps of electron-transfer reactions.
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| 6. |
- Visibile, Alberto, 1989, et al.
(författare)
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An Alternative Method of Measuring Area Specific Resistance of Chromia Scales Using Electrochemical Impedance Spectroscopy
- 2023
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Ingår i: Journal of the Electrochemical Society. - : The Electrochemical Society. - 0013-4651 .- 1945-7111. ; 170:3
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Tidskriftsartikel (refereegranskat)abstract
- A novel method that employs electrochemical impedance spectroscopy (EIS) is developed to characterize the oxide scale resistance and thickness of Crofer 22 APU after exposure at 800 degrees C in humidified air. Crofer 22 APU, is one of the most commonly used materials for solid oxide fuel cell (SOFC) interconnects, an application for which oxide scale resistance is of paramount importance. The kinetics of oxide growth were studied for up to 6,000 h using three different techniques: electron microscopy of cross-sections, gravimetry, and EIS capacitance measurements of the oxide scale. EIS was used to evaluate the scale thickness starting from the material capacitance, and the material resistance at high temperature was estimated using extrapolation of the impedance values at room temperature. The result obtained with this novel EIS method are comparable to those obtained using conventional techniques, and in addition, the new method is cheaper, faster, and more reliable. Moreover, it enables repetitive exposures of the same sample without altering the specimen properties.
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