| 1. |
- Anderson, Leif G., et al.
(författare)
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The effect of the Siberian tundra on the environment of the shelf seas and the Arctic Ocean
- 1999
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Ingår i: Ambio. - 0044-7447. ; 28:3, s. 270-280
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Tidskriftsartikel (refereegranskat)abstract
- The Tundra Ecology -94 expedition investigated inflow of inorganic and organic carbon to the shelf seas by river runoff, and its transformation by biochemical processes in seawater and sediment. In addition, anthropogenic radionuclides, 137Cs, 90Sr, and 239,240Pu, were studied in water and sediments. The distribution of dissolved inorganic carbon indicates that the majority of the Ob and Yenisey discharges flow into the Laptev Sea before entering the central Arctic Ocean. The sediment study shows that there is a marked difference in benthic oxygen uptake, efflux of dissolved inorganic carbon and nutrients between localities. 137Cs activity from the Chernobyl accident is 30% in the Barents, Kara, and Laptev Seas. 137Cs increased from 5-8 Bq m-3 in Barents Sea, 5-13 Bq m-3 in the Kara Sea to 8-15 Bq m-3 in the Laptev Sea, but with locally low concentrations at the river mouths. Corresponding values for 90Sr were 2.5, 3, and 4 Bq m-3, respectively.
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| 2. |
- Ceberg, Crister, et al.
(författare)
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A stochastic model for subcellular dosimetry in boron neutron capture therapy
- 1995
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 1361-6560 .- 0031-9155. ; 40:11, s. 1819-1830
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Tidskriftsartikel (refereegranskat)abstract
- The therapeutic effectiveness of boron neutron capture therapy is highly dependent on the microscopic distribution of the administered boron compound. Two boron compounds with different uptake mechanisms in the tumour cells may thus cause effects of different degrees even if the macroscopic boron concentrations in the tumour tissue are the same. This difference is normally expressed quantitatively by the so-called relative local efficiency (RLE). In this work, a stochastic model for the subcellular dosimetry has been developed. This model can be used to calculate the probability for an energy deposition above a certain threshold level in the cell nucleus due to a single neutron capture reaction. If a threshold cell-kill function is assumed, and if the dose is low enough that multiple energy depositions are rare, the model can also be applied to calculations of the survival probability for a cell population. Subcellular boron distributions in rats carrying RG 2 rat gliomas were measured by subcellular fractionation after administration of two different boron compounds: a sulphydryl boron hydride (BSH) and a boronated porphyrin (BOPP). Based on these data, the RLE factors were then calculated for these compounds using the stochastic model.
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| 3. |
- Ceberg, Crister, et al.
(författare)
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Performance of sulfhydryl boron hydride in patients with grade III and IV astrocytoma: a basis for boron neutron capture therapy
- 1995
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Ingår i: Journal of Neurosurgery. - 0022-3085. ; 83:1, s. 79-85
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the rationale of boron neutron capture therapy (BNCT) for the treatment of Grade III and IV astrocytoma. The European Community joint research program on BNCT plans to use sulfhydryl boron hydride (BSH) in clinical trials. The work presented here, examines the performance of BSH in eight patients with Grade III and IV astrocytoma using a measurement technique which precisely correlates the boron uptake with the histology of the tumor and the peritumoral brain. Astrocytomas are exceptionally heterogeneous and spread migrating tumor cells into the surrounding brain. The patients were infused with 50 mg BSH per kilogram of body weight at 12, 18, 24 or 48 hours before surgery. At the time of operation, specimens were obtained of the tumor, skin, muscle, dura, blood, urine, and, when surgically possible, the brain adjacent to tumor. In three patients the intracellular boron distribution was investigated by subcellular fractionation. The blood clearance was biphasic with half-lives of 0.6 and 8.2 hours. After 3 days, approximately 70% of the dose injected was excreted in the urine. The maximum boron concentration in the tumor was 20 ppm, 12 hours after the infusion. The tumor-to-blood ratios ranged between 0.2 and 1.4, with the highest values after 18 to 24 hours. In the brain specimens the boron concentration never exceeded 1 ppm. This work confirms a selective uptake of boron in the tumor compared to the surrounding brain and that boron, to some extent, is incorporated in the tumor cells.
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| 4. |
- Widell, Anders, et al.
(författare)
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Epidemiologic and molecular investigation of outbreaks of hepatitis C virus infection on a pediatric oncology service
- 1999
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Ingår i: Annals of Internal Medicine. - : American College of Physicians. - 0003-4819. ; 130:2, s. 130-134
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Despite screening of blood donors, hepatitis C virus (HCV) infection can occur in patients who receive multiple transfusions. OBJECTIVE: To clarify mechanisms of nosocomial transmission of HCV. DESIGN: Epidemiologic and molecular analyses of hepatitis C outbreaks. SETTING: Pediatric oncology ward. PATIENTS: Children with cancer. MEASUREMENTS: Epidemiologic analysis, HCV RNA detection, genotyping, and hypervariable region 1 (HVR1) sequencing. RESULTS: Ten cases of infection with acute HCV genotype 3a occurred between 1990 and 1993. Sequencing of HVR1 revealed three related strains. Despite an overhaul of hygiene procedures, a patient infected with genotype 1b generated nine subsequent infected patients in 1994. Several patients had high virus titers and strongly delayed anti-HCV antibody responses. All had permanent intravenous catheters. Multidose vials used for flushing or treatment had probably been contaminated during periods of overlapping treatment. CONCLUSIONS: Contamination of multidose vials was the most likely mode of HCV transmission; therefore, use of such vials should be restricted. Rigorous adherence to hygiene routines remains essential to preventing transmission of bloodborne infections.
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| 5. |
- Persson, Bertil
(författare)
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Basic Deformations of High-Performance Concrete at Early Ages.
- 1997
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Ingår i: Nordic Concrete Research. - 0800-6377. ; 20, s. 59-74
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Creep and shrinkage are two major problems to be discussed in concrete design. Basic creep is studied during constant loading, temperature and moisture conditions, i.e. no exchange of moisture takes place to or from the specimen during the test period. In this paper an experimental and numerical study of basic creep of High Performance Concrete (HPC) is outlined. For this purpose cylinders and cubes were cast. Quasi-instantaneous deformation and basic creep including autogenous shrinkage were observed over 3 years. Analysis's of elastic modulus, early creep and long-term creep including autogenous shrinkage are presented. HPC autogenous shrinkage had a great influence on the results. The autogenous shrinkage in its turn is caused by the self-desiccation of HPC. The study was carried out in 1992 through 1994 at Lund Institute of Technology, Division of Building Materials, Lund, Sweden.
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| 9. |
- Persson, Bertil
(författare)
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Brosystem mellan Honchu och Shikoku: Japanska rekordbroar
- 1999
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Ingår i: Bygg & teknik. - 0281-658X. ; , s. 56-60
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- I denna artikel redovisas en sammanställning av ett stort antal broprojekt mellan den japanska huvudön Honchu och den söder därom belägna ön Shikoku. Först ges en bakgrund vad gäller andra stora hängbroar och snedkabelbroar i världen. Därefter belyses och specifieras de aktuella japanska broarna i detalj. Sammantaget är brosystemen mellan Honchu och Shikoku imponerande inte bara vad gäller spännvidd (maximalt 1.990 m för en av hängbroarna samt 890 m för en snedkabelbro) utan även beträffande antalet broar, totalt 19 stycken broar med stor spännvidd.
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| 10. |
- Persson, Bertil
(författare)
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Chemical Shrinkage and Self-Desiccation in Portland Cement Based Mortars.
- 1999
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Ingår i: Concrete Science and Engineering. - 1295-2826. ; 1:4, s. 228-237
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Tidskriftsartikel (refereegranskat)abstract
- This article outlines an experimental and numerical study of self-desiccation and chemical shrinkage in Portland cement mortars, with or without silica fume. For this purpose 9 different cement mortars were cast in 90 pycnometers (study of chemical shrinkage and hydration) or 180 glass flasks (study of self-desiccation and hydration). Chemical shrinkage was observed for 14 days and self-desiccation for 70 days. Parallel studies were carried out on evaporable water (only cement mortar with sealed curing) and hydration. The results indicate that silica fume slightly affects the specific volume of the hydrated water. The silica fume also had a substantial (physical) effect on the self-desiccation when used in Portland cement mortars.
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