| 1. |
- Hobbs, R. W., et al.
(författare)
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Integrated seismic studies of the Baltic shield using data in the Gulf of Bothnia region
- 1993
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Ingår i: Geophysical Journal International. - 0956-540X .- 1365-246X. ; 112:3, s. 305-324
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Tidskriftsartikel (refereegranskat)abstract
- In the autumn of 1989 a co-operative experiment involving 12 research institutions in northwestern Europe collected 2268 km of deep seismic reflection profiles in the Gulf of Bothnia and the Baltic Sea. the 121 litre airgun array used for this profiling was also recorded by 62 muiticomponent land stations to provide coincident refraction surveys, fan-spreads, and 3-D seismic coverage of much of the Gulf of Bothnia. We thus have potentially both high-resolution impedance contrast images as well as more regional 3-D velocity models in both P- and S-waves. In the Bothnian Bay a south-dipping, non-reflective zone coincides with the conductive Archaean-Proterozoic boundary onshore in Finland. Between the Bothnian Bay and Bothnian Sea observed reflectivity geometries and velocity models at Moho depths suggest structures inherited from a 1.9Ga subduction zone; the upper crust here appears to have anomalously low velocity. Within the Bothnian Sea, reflectivity varies considerably beneath the metasedimentary/granitoid rocks of the Central Svecofennian Province (CSP) and the surrounding metavolcanic-arc rocks. Numerous dipping reflectors appear throughout the metavolcanic crust, whereas the CSP has little reflectivity. Wide-angle reflections indicate that the metasedimentary crust of the Bothnian Basin is 10 km thicker than the neighbouring Svecofennian subprovinces. Near the Åland archipelago Rapakivi granite plutons exhibit bright reflections, a contrast to the usual non-reflective plutons elsewhere in western Europe. Additional dipping reflections deep in the crust of this area may support models of rifting and crustal thinning during emplacement of the 1.70-1.54 Ga Rapakivi granites. Coeval gabbroic/anorthositic magmatism may explain the high reflectivity and high velocity of these plutons. the c. 1.25 Ga mafic sills and feeder dykes of the Central Scandinavian Dolerite Group also produce clear reflections on both near- and far-offset seismic sections. Continued modelling will produce better velocity models of the crust and better constrained contour maps of crustal thickness in this part of the Baltic shield.
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| 2. |
- Berthelsen, A., et al.
(författare)
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Recording marine airgun shots at offsets between 300 and 700 km
- 1991
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 18:4, s. 645-648
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Tidskriftsartikel (refereegranskat)abstract
- This paper demonstrates that - under favorable conditions - by using multichannel recording and subsequent stacking of adjacent records marine airgun shots have been detected at offset distances up to 700 km, the maximum offset at which the authors attempted to record data.^Besides a powerful airgun array, a low noise environment at the recording site and the elimination of static shifts are the prerequisites to obtain refracted and reflected arrivals from the crust and upper mantle at such large offsets.^Primary arrivals detected at offsets between 400 and 700 km image the upper mantle from 70 to about 120 km depth.^Stacking of neighboring shots and/or receivers successfully increases the signal-to-noise ratio, if the traces have been corrected for offset differences, which requires knowledge of the apparent phase velocities.^The data presented here were collected in autumn 1989 during the BABEL Project on the Baltic Shield.
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| 3. |
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| 4. |
- Bergqvist, D, et al.
(författare)
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Low molecular weight heparin for thromboprophylaxis and epidural/spinal anaesthesia--is there a risk?
- 1992
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Ingår i: Acta Anaesthesiologica Scandinavica. - 0001-5172. ; 36:7, s. 605-609
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Tidskriftsartikel (refereegranskat)abstract
- This article reviews the problem of bleeding in connection with epidural/spinal anaesthesia, with special emphasis on the use of low molecular weight heparins for thromboprophylaxis. There are methodological difficulties to studying the problem in a scientifically correct way because of the rarity of the complication. However, from the data in the literature there are no indications of an increased risk in using the combination of low molecular weight heparin in prophylactic doses and epidural/spinal anaesthesia. So far, there is only a single case report, of spinal haematoma, although low molecular weight heparins have been used in combination with epidural/spinal anaesthesia in at least 1,000,000 patients. In controlled studies, at least 10,000 patients have been given the combination without complications.
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| 5. |
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| 6. |
- Bergqvist, D, et al.
(författare)
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The cost-effectiveness of prevention of post-operative thromboembolism
- 1990
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Ingår i: Acta chirurgica Scandinavica. Supplementum. - 0301-1860. ; 556, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- In recent years, value for money in health care has become of increasing concern. There are various ways to perform an economic evaluation, the most simple being a cost-effectiveness analysis, where differences in costs will influence the choice between methods. Cost-utility and cost-benefit analyses represent more advanced forms of economic evaluations. In this cost-effectiveness analysis, the following three strategies aimed at solving the problem of post-operative thromboembolic complications were compared: (a) no prophylaxis but treatment of occurring complications, (b) general prophylaxis with low-dose heparin for patients over 40 years of age and (c) selective treatment based on post-operative surveillance with a fibrinogen uptake test. Moreover, these alternatives were evaluated for three types of surgery: general abdominal surgery, cholecystectomy and elective hip surgery. Costs for thromboembolic and haemorrhagic complications were estimated from data available for patients hospitalized in Malmo. A sensitivity analysis was made with regard to the frequency of thrombosis, prophylactic effect and treatment costs. Health care costs would be minimized with general prophylaxis in hip and general surgery, whereas no prophylaxis is the most cost-effective alternative in cholecystectomy patients, i.e. with a frequency of thrombosis below 8%. General prophylaxis minimized the duration of patients' health losses due to thromboembolic disease in general, as well as in elective hip surgery. After cholecystectomy, no difference in health loss for the individual was found between the alternative of no prophylaxis and general prophylaxis. Selective treatment was always the least satisfactory alternative in all categories and always the most expensive.
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| 7. |
- Bergqvist, D, et al.
(författare)
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Thromboprophylaxis in emergency surgery
- 1993
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Ingår i: Haemostasis. - 0301-0147. ; 23:Suppl. 1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- Except for hip fracture surgery, emergency surgery has been only exceptionally studied concerning thromboprophylaxis. There are, however, several reasons to believe the frequency to be fairly high and that the patient group would be in need of prophylaxis. This paper discusses various emergency situations and also gives the design for an ongoing controlled study on the effect of postoperative start of thromboprophylaxis with low molecular weight heparin in emergency abdominal surgery.
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| 8. |
- Mätzsch, Thomas, et al.
(författare)
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Effects of low molecular weight heparin and unfragmented heparin on induction of osteoporosis in rats
- 1990
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Ingår i: Thrombosis and Haemostasis. - 0340-6245. ; 63:3, s. 505-509
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Tidskriftsartikel (refereegranskat)abstract
- A comparison between the effect of low molecular weight heparin (LMWH) and unfragmented heparin (UH) on induction of osteoporosis was made in 60 rats treated with either UH (2 IU/g bw), LMWH in 2 doses (2 XaI U/g or 0.4 XaI U/g) or placebo (saline) for 34 days. Studied variables were: bone mineral mass in femora; fragility of humera; zinc and calcium levels in serum and bone ash and albumin in plasma. A significant reduction in bone mineral mass was found in all heparin-treated rats. There was no difference between UH and LMWH in this respect. The effect was dose-dependent in LMWH-treated animals. The zinc contents in bone ash were decreased in all heparin-treated rats as compared with controls. No recognizable pattern was seen in alterations of zinc or calcium in serum. The fragility of the humera, tested as breaking strength did not differ between treatment groups and controls. In conclusion, if dosed according to similar factor Xa inhibitory activities, LMWH induces osteoporosis to the same extent as UH and in a dose-dependent manner. The zinc content in bone ash was decreased after heparin treatment, irrespective of type of heparin given.
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| 9. |
- Pedersen, P C, et al.
(författare)
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Pharmacokinetics of a low molecular weight heparin, logiparin, after intravenous and subcutaneous administration to healthy volunteers
- 1991
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Ingår i: Thrombosis Research. - 1879-2472. ; 61:5-6, s. 477-487
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Tidskriftsartikel (refereegranskat)abstract
- In six healthy volunteers we have estimated the pharmacokinetic parameters of the anti factor Xa (AXa) and anti factor IIa (AIIa) activities of a LMW heparin, Logiparin. For the AXa the following parameters were estimated in a 1-compartment model (mean and 95% confidence limits in brackets): elimination half life 82 minutes (60-127 min), absorption half life (s.c. inj.) 200 minutes (137-368 min), bioavailability 90% (24-156%), and apparent volume of distribution 3.9 l (3.1-5.2 l). The plasma activity was linearly correlated to the dose given and to the body weight of the volunteer. For the AIIa the parameters estimated in a 1-compartment model were: elimination half life 71 minutes (52-115 min), absorption half life 257 minutes (133-3442 min), bioavailability 67% (44-90%), and apparent volume of distribution 10.1 l (7.2-16.7 l). The plasma activity was dependent on dose and body weight but it also seemed to be influenced by individual factors. This study shows that the absorption rate is the rate limiting factor and the explanation for the long lasting effect of this LMW heparin after subcutaneous injection. The slow absorption rate and the high bioavailability are probably the major advantages of LMW heparins compared to conventional heparin.
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