| 1. |
- Hanås, Ragnar, et al.
(författare)
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Diagnosis of the cause of malfunction of indwelling catheters for insulin injections by the use of digital fluoroscopy
- 2000
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Ingår i: Pediatric Radiology. - : Springer Science and Business Media LLC. - 0301-0449 .- 1432-1998. ; 30:10, s. 674-676
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Tidskriftsartikel (refereegranskat)abstract
- Background. Subcutaneous indwelling catheters are used for reducing pain when injecting insulin and other drugs.Objective. To use digital fluoroscopy for the diagnosis of catheter malfunction.Material and methods. Seven children (aged 5–11 years) with diabetes mellitus were studied. They used indwelling catheters (Insuflon) for insulin injections. Contrast medium was injected into the problem catheter.Results. The subcutaneous position of the catheter was correct in all cases, but we found two cases of delayed absorption caused by lipohypertrophy and one case of leakage.Conclusions. Digital fluoroscopy is a useful method for determining potential problems with indwelling catheters.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Pundziute-Lyckå, A, et al.
(författare)
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The incidence of Type I diabetes has not increased but shifted to a younger age at diagnosis in the 0-34 years group in Sweden 1983-1998.
- 2002
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 45:6, s. 783-91
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: To analyse the incidence of Type I (insulin-dependent) diabetes mellitus in the 0-34 years age group in Sweden 1983-1998.METHODS: Incidence and cumulative incidence per 100 000 and Poisson regression analysis of age-period effects was carried out using 11 751 cases from two nation-wide prospective registers.RESULTS: Incidence (95%-CI) was 21.4 (20.8-21.9) in men and 17.1 (16.6-17.5) in women between 0 and 34 years of age. In boys aged 0-14 and girls aged 0-12 years the incidence increased over time, but it tended to decrease at older age groups, especially in men. Average cumulative incidence at 35 years was 748 in men and 598 in women. Cumulative incidence in men was rather stable during four 4-year periods (736, 732, 762, 756), while in women it varied more (592, 542, 617, 631). In males aged 0-34 years, the incidence did not vary between the 4-year periods ( p=0.63), but time changes among the 3-year age groups differed ( p<0.001). In females the incidence between the periods varied ( p<0.001), being lower in 1987-1990 compared to 1983-1986, but time changes in the age groups did not differ ( p=0.08). For both sexes median age at diagnosis was higher in 1983-1986 than in 1995-1998 ( p<0.001) (15.0 and 12.5 years in males; 11.9 and 10.4 in females, respectively).CONCLUSION/INTERPRETATION: During a 16-year period the incidence of Type I diabetes did not increase in the 0-34 years age group in Sweden, while median age at diagnosis decreased. A shift to younger age at diagnosis seems to explain the increasing incidence of childhood Type I diabetes.
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| 6. |
- Pundziute-Lycka, A, et al.
(författare)
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The incidence of Type I diabetes has not increased but shifted to a younger age at diagnosis in the 0-34 years group in Sweden 1983 to 1998
- 2002
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 45:6, s. 783-791
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis. To analyse the incidence of Type I (insulin-dependent) diabetes mellitus in the 0-34 years age group in Sweden 1983-1998. Methods. Incidence and cumulative incidence per 100 000 and Poisson regression analysis of age-period effects was carried out using 11 751 cases from two nation-wide prospective registers. Results. Incidence (95%-CI) was 21.4 (20.8-21.9) in men and 17.1 (16.6-17.5) in women between 0 and 34 years of age. In boys aged 0-14 and girls aged 0-12 years the incidence increased over time, but it tended to decrease at older age groups, especially in men. Average cumulative incidence at 35 years was 748 in men and 598 in women. Cumulative incidence in men was rather stable during four 4-year periods (736, 732, 762, 756), while in women it varied more (592, 542, 617, 631). In males aged 0-34 years, the incidence did not vary between the 4-year periods (p=0.63), but time changes among the 3-year age groups differed (p<0.001). In females the incidence between the periods varied (p<0.001), being lower in 1987-1990 compared to 1983-1986, but time changes in the age groups did not differ (p=0.08). For both sexes median age at diagnosis was higher in 1983-1986 than in 1995-1998 (p<0.001) (15.0 and 12.5 years in males, 11.9 and 10.4 in females, respectively). Conclusion/interpretation. During a 16-year period the incidence of Type I diabetes did not increase in the 0-34 years age group in Sweden, while median age at diagnosis decreased. A shift to younger age at diagnosis seems to explain the increasing incidence of childhood Type I diabetes.
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| 7. |
- Thorén, P., et al.
(författare)
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Chemical abundances in cool metal rich disk dwarf stars
- 2000
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Ingår i: Astronomy and Astrophysics. - 1432-0746. ; 363, s. 692-704
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Tidskriftsartikel (refereegranskat)abstract
- The present study of spectra of twelve metal-rich cool dwarf stars, carefully selected in order to cover a range of temperatures ( K), is a follow up on Feltzing & Gustafsson (1998) with the aim to understand the apparent over-ionization and anomalous elemental abundances found by them for the K dwarf stars in their sample. Our method of analysis employs synthetic spectra of the full spectrum both to constrain the continuum level and to derive abundances. It is shown that by using this method and imposing a strict excitation equilibrium (possible to do because of the care in selection of observed Fe I lines) we are able to show that metal-rich K dwarf stars do not show anomalous stellar abundances, as indicated in Feltzing & Gustafsson (1998), and can, with reasonable efforts, be analyzed in order to increase the number of metal-rich stars with useful chemical abundances. With abundance analysis by means of spectrum synthesis and assuming Local Thermodynamic Equilibrium (LTE) the abundances of Na, Si, Ca, Sc, Ti, V, Cr, Fe, Co, Ni, and Nd have been derived. Also ionization balance is satisfied for Fe and Cr after correcting the stellar effective temperatures such that both ionization and excitation equilibrium were satisfied. In addition, spectra from five cool dwarf stars of the Feltzing & Gustafsson (1998) sample have been analyzed with the methods used in this work. They show essentially the same abundance patterns as the new stars in this sample.
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| 8. |
- Lindgren, Björn, et al.
(författare)
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Evaluation of a new wind tunnel with expanding corners
- 2004
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Ingår i: Experiments in Fluids. - : Springer Science and Business Media LLC. - 0723-4864 .- 1432-1114. ; 36:1, s. 197-203
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Tidskriftsartikel (refereegranskat)abstract
- A new low-speed, closed-circuit, closed-test-section wind tunnel, called BLT, has been designed and built at KTH. The turbulence intensity in the test section is <0.04%, the total pressure variation is <+/-0.1% and the temperature variation is <+/-0.07degreesC over the cross-sectional area. The concept of expanding corners with an expansion ratio of 1.32 first investigated by Lindgren et al. in 1998, has been implemented successfully with a two-dimensional total pressure loss coefficient of 0.047 at a chord Reynolds number of 200,000. It is comparable to or even better than the values found in most wind tunnels using nonexpanding corners. The findings in this study prove the usefulness of expanding corners to achieve a compact wind tunnel circuit design without compromising the flow quality.
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| 9. |
- Eklund, Leif, et al.
(författare)
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The influence of wind on spiral grain formation in conifer trees
- 2000
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Ingår i: Trees. - : Springer. - 0931-1890 .- 1432-2285. ; 14, s. 324-328
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Tidskriftsartikel (refereegranskat)abstract
- The correlation between spiral grain formationand crown asymmetry was investigated in 18 Scots pine(Pinus sylvestris L.) and 17 Norway spruce [Picea abies(L.) Karst.] trees selected from clones of each speciesgrowing in the south of Sweden. The angle between thelongitudinal direction of the tracheids in the outermostyear ring compared to the longitudinal direction of thestem was measured by scribing lines which followed thedirection of the tracheids. The crown asymmetry wasmeasured by taking photographs of the trees followed bya simple picture analysis of the tree. Wind data for thegrowing seasons of 1997 and 1998 were obtained fromthe Swedish Meteorological and Hydrological Institute.The results showed a significant correlation between theangle of the tracheids compared to the stem longitudinaldirection going from a left-handed angle if the trees hada crown projected to the north towards a right-handedangle the more the crown projects to the south.
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| 10. |
- Borg, Henrik, et al.
(författare)
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Evaluation of the new ADA and WHO criteria for classification of diabetes mellitus in young adult people (15-34 yrs) in the Diabetes Incidence Study in Sweden (DISS)
- 2003
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 46:2, s. 173-181
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis. We aimed to evaluate how an aetiology-based classification, as recommended in the ADA and WHO guidelines for classification of diabetes mellitus, matches clinical judgement in the Diabetes Incidence Study in Sweden (DISS), a study covering incident cases of diabetic patients aged 15 to 34 years. Methods. During a 1-year period (1998), blood samples were taken at diagnosis and 4 months (median) thereafter. Patients were classified according to clinical judgement by the reporting physicians and assessments of islet antibodies (ICA, GADA, and IA-2A) and plasma C-peptide. Results. In 1998, 422 patients were registered in DISS. Among the 313 patients participating in the follow-up, most with clinical Type 1 diabetes (185/218, 85%, 95% CI 79-89%) were islet antibody positive (ab+) at diagnosis. In addition, 14 out of 58 (24%, 14-37%) with clinical Type 2 diabetes and 21 out of 37 (57%, 40-73%) with unclassifiable diabetes were antibody positive at diagnosis. Further to this, 4 out of 33 (12%, 3-28%) were antibody negative with clinical Type 1 diabetes and 4 out of 44 (9%, 3-22%) with Type 2 had converted to antibody positive at follow-up. Among those who were constantly antibody negative, 10 out of 29 (34%, 18-54%) with clinical Type 1 and 1 out of 16 (6%, 0-30%) with unclassifiable diabetes had fasting plasma C-peptide concentrations below the normal range (<0.25 nmol/l) at follow-up. Conclusion/interpretation. Most young adults with clinical Type 1 diabetes (199/218, 91%) had objective Type 1 (ab+ at diagnosis/follow-up and/or low fasting plasma C-peptide concentrations at follow-up), as did one third (18/58, 31%) with clinical Type 2 diabetes and more than half (22/37, 59%) with unclassifiable diabetes. About 10% of those who were antibody negative converted to antibody positive. Our study underlines that a classification considering aetiology is superior to clinical judgement.
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| 11. |
- Bjøro, K, et al.
(författare)
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Liver transplantation in patients over 60 years of age
- 2000
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Ingår i: Transplant International. - : Frontiers Media SA. - 0934-0874 .- 1432-2277. ; 13:Suppl 1, s. S165-S170
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Tidskriftsartikel (refereegranskat)abstract
- Liver transplantation was previously only offered to patients under 60 years of age. We have analyzed the outcome after acceptance on the waiting list and after liver transplantation of patients over 60 years old. A total of 150 patients over 60 years old were listed for a first liver transplantation during 1990-1998. The annual number increased throughout the period. Primary biliary cirrhosis, primary sclerosing cholangitis, and acute hepatic failure were the most frequent diagnoses. A total of 119 patients received a first liver allograft. The patient 1-year survival was 75% and 3-year survival 62%, which was not significantly lower (P = 0.21) than that of the younger patients. When correcting for year of transplantation, the survival was, however, moderately but significantly lower than among the younger patients. Survival among those > 65 years (n = 38) did not differ from that of patients 60-65 years of age (n = 81). We conclude that an increasing number of patients over 60 years old can be listed for liver transplantation and receive a liver allograft with highly satisfying results.
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| 12. |
- Marklund, Göran T., et al.
(författare)
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Astrid-2, an advanced microsatellite for auroral research
- 2001
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 19:6, s. 589-592
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Tidskriftsartikel (refereegranskat)abstract
- The successful launch of the Swedish microsatellite Astrid-2 in December 1998 began a new era of auroral research, with advanced microprobes of 30 kg or less used as research tools. Innovative technologies and low-mass solutions were used for the sensors and deployment systems to allow a fairly complete set of scientific instruments within the 10 kg allocated for the scientific payload. A newly developed wire boom deployment system proved to function excellently. During its seven month lifetime Astrid-2 collected more than 26 Gbytes of high-quality data of auroral electric and magnetic fields, and auroral particle and plasma characteristics from approximately 3000 orbits at an inclination of 83 degrees and an altitude of about 1000 km. Scientific results cover a broad range of topics, from the physics of energization of auroral particles to how the magnetosphere responds to the energy input from the solar wind and global magnetic field modelling. The fulfilment of both the technological and the scientific mission objectives has opened entirely new possibilities to carry out low-budget multipoint measurements in near-Earth space.
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| 13. |
- Karlsson, Jan, et al.
(författare)
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Bacterioplankton production in lakes along an altitude gradient in the subarctic north of Sweden
- 2001
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Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 42:3, s. 372-382
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Tidskriftsartikel (refereegranskat)abstract
- We examined changes in bacterioplankton standing stock and production in subarctic lakes in the north of Sweden to elucidate their coupling to lake physical, chemical, and biological characteristics. Sixteen lakes situated along an altitude gradient extending from the coniferous forest to the high-alpine belt were studied during 1998 and 1999. The summer mean bacterial numbers and production varied substantially between the lakes, with a general trend toward decreasing values with increasing altitude. The results demonstrate that P probably restricted bacterial utilization of DOC in the coniferous forest lakes, while low DOC concentrations limited bacterial growth during the summer in the alpine lakes. The primary production of plankton was insufficient to support bacterial production in the lakes. High input of allochthonous DOC to the alpine lakes in spring was sufficient both to increase the bacterial production and to induce P-limitation. As a consequence, there was a tendency toward higher bacterial activity in the spring compared to the summer in the alpine lakes. The results indicate that most of the bacterial standing stock and production are supported by allochthonous DOC plus DOC from benthic production, and more or less limited by the phosphorus supply. We therefore suggest that bacteria populations in subarctic lakes may be indirectly affected by climate variations through its impact on the input of DOC and nutrients from the lake catchments.
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| 14. |
- Walther, Sten, et al.
(författare)
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Comparison of the Glasgow Coma Scale and the Reaction Level Scale for assessment of cerebral responsiveness in the critically ill
- 2003
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Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 29:6, s. 933-938
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The Glasgow Coma Scale (GCS) is a well-known source of error in outcome prediction models. We compared assessment of cerebral responsiveness with the GCS and the Reaction Level Scale (RLS) in two otherwise similar outcome prediction models. Design and setting: Prospective, observational study in a general intensive care unit. Patients and participants: All admissions of patients with or at risk of developing impaired brain function between 1997 and 1998 (n=534). Measurements and results: Admissions were scored by RLS and APACHE II (includes scoring with the GCS). The RLS scores were transformed to APACHE II central nervous system scores according to a predetermined protocol. APACHE II estimated probability of death was calculated conventionally with the GCS and the RLS. Vital status 90 days after admission was secured from a national database. Bias and precision was 0.5% and 16.6%, respectively. The area under receiver operating characteristic curves was slightly but significantly greater with the RLS-based APACHE 11 model than with the GCS-based model (0.92 vs. 0.90). Discrimination was improved primarily in admissions with low and intermediate probability of death. Conclusions: Scoring of cerebral responsiveness with the RLS instead of the GCS was associated with minimal bias of the APACHE 11 probability of death estimate. Assessment of consciousness in critically ill with the RLS deserves further evaluation.
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| 15. |
- Melander, Eva, et al.
(författare)
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Utilisation of antibiotics in young children: opposite relationships to adult educational levels in Danish and Swedish counties.
- 2003
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Ingår i: European Journal of Clinical Pharmacology. - : Springer Science and Business Media LLC. - 1432-1041 .- 0031-6970. ; 59:4, s. 331-335
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Tidskriftsartikel (refereegranskat)abstract
- Background. Antibiotic utilisation varies profoundly among and within countries, and the extent of antibiotic utilisation correlates with the frequency of bacterial resistance, particularly among children. Hence, it is important to assess which factors may influence prescribing. In addition to variations in morbidity, health-care organisation, drug regulatory and supply systems, prescriber's attitudes, parents' behaviour, attitudes and socio-economic positions seem important. We compared socio-economic position (educational level of adults) and antibiotic utilisation in children in the municipalities within a Danish and a Swedish county which are geographically close, have similar social and economic development, and similar drug regulatory and supply systems. Methods. Data on antibiotic utilisation (1998), expressed in defined daily doses per 1000 inhabitants per day (DDD/TID), were obtained from the Copenhagen County Health Insurance register and from the National Corporation of Swedish Pharmacies. Data on municipal educational levels were obtained from Statistics Denmark and Statistics Sweden. Results. The utilisation of antibiotics in 0- to 6-year-old children was higher in the Swedish than in the Danish county but varied between the municipalities within both the Swedish (9.6-17.7 DDD/TID) and the Danish (8.0-12.9 DDD/TID) counties. Most notably, utilisation rates correlated negatively with the education levels in the Danish (r=-0.539, P=0.021) but positively in the Swedish (r=+0.390, P=0.025) municipalities. Conclusion. The observed variations in antibiotic prescribing may reflect different parental and/or prescriber attitudes towards use of antibiotics and they emphasise that antibiotic prescribing is influenced by factors other than the prevalence of bacterial infections. Relationships between socio-economic position (educational level) and drug utilisation should not be generalised from one area to another.
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| 16. |
- McClanahan, Tim, et al.
(författare)
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Responses of algae, corals and fish to the reduction of macroalgae in fished and unfished patch reefs of Glovers Reef Atoll, Belize
- 2001
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Ingår i: Coral Reefs. - : Springer. - 0722-4028 .- 1432-0975. ; 19:4, s. 367-379
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Tidskriftsartikel (refereegranskat)abstract
- Macroalgae were experimentally reduced by approximately 2.5 kg/m2 on eight similar-sized patch reefs of Glovers Reef Atoll, Belize, in September 1998. Four of these reefs were in a protected "no-take" zone and four were in a "general use" fishing zone. Eight adjacent reefs (four in each management zone) were also studied as unmanipulated controls to determine the interactive effect of algal reduction and fisheries management on algae, coral, fish, and rates of herbivory. The 16 reefs were sampled five times for 1 year after the manipulation. We found that the no-fishing zone had greater population densities for 13 of 30 species of fish, including four herbivorous species, but lower herbivory levels by sea urchins. However, there was lower stony coral cover and higher macroalgal cover in the "no-take" zone, both prior to and after the experiment. There were no significant effects of management on the percent cover of fleshy macroalgae. The algal reduction resulted in an increase in six fish species, including four herbivores and two which feed on invertebrates. One species, Lutjanus griseus, declined in experimental reefs. Macroalgal biomass quickly recovered from the reduction in both management areas within a few months, and by species-level community measures within 1 year, while stony coral was reduced in all treatments. Coral bleaching and Hurricane Mitch disturbed the site at the beginning of the study period and may explain the loss of stony coral and rapid increase in erect algae. We suggest that reducing macroalgae, as a technique to restore turf and encrusting coralline algae and stony corals, may work best after reefs have been fully protected from fishing for a period long enough to allow herbivorous fish to recover (i.e. >5 years). Further ecological studies on Glovers Reef are required to understand the shift from coral to algal dominance that has occurred on this reef in the last 25 years.
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| 17. |
- Bergdahl, Jan, et al.
(författare)
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Coping and self-image in patients with visual display terminal-related skin symptoms and perceived hypersensitivity to electricity
- 2004
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 77:8, s. 538-542
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of the present study was to measure coping resources and self-image in patients with visual display terminal (VDT)-related skin symptoms and hypersensitivity to electricity (HE).Methods: From 1980 to 1998, 350 patients with electrical sensitivity were registered. The patients were subdivided into two groups: patients with skin symptoms evoked by VDTs, television screens, and fluorescent-light tubes and patients with so-called hypersensitivity to electricity with multiple symptoms evoked by exposure to different electrical environments. A questionnaire was sent to all patients and contained the coping resources inventory (CRI) and the structural analysis of social behaviour (SASB) in order for us to measure coping resources and self-image, respectively. The CRI and SASB scores were compared with those of control groups. Two hundred and fifty respondents (73%) returned the questionnaire, 200 (78.5% women) in the VDT group and 50 (62% women) in the HE group.Results: The patient group rated high on the CRI spiritual/philosophical scale and high on the SASB spontaneous, positive and negative clusters but low on the controlled cluster. The female patients scored high on the CRI emotional scale. The VDT group rated lower than the controls on the SASB controlled cluster and higher on both the positive and negative cluster. The HE group scored higher than the control group on the SASB spontaneous and positive clusters. The women in the HE group scored higher on the CRI cognitive and CRI total scale than the VDT group and control group and higher on the CRI emotional scale than the controls. The women in the HE group rated higher than both the women in the VDT and control groups on the SASB spontaneous and positive clusters.Conclusions: The deviant self-image found in these patients, especially the female HE patients, support the view that VDT and HE symptoms can be stress related. In the clinic, a trustful alliance should be established with the patient in order for a more realistic view to be achieved of the capacity.
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| 18. |
- Dellve, Lotta, 1965, et al.
(författare)
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Work-system risk factors for permanent work disability among home-care workers: a case-control study.
- 2003
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Ingår i: International archives of occupational and environmental health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 76:3, s. 216-24
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: There is a growing need for home-care services in western societies. As home-care workers show high levels of absence related to poor health it is important that we broaden our knowledge about what factors in the work system contribute to this. The aim of this study was to explore and estimate the impact of the work system on permanent work disability and its relative importance compared with home-life risks among home-care workers. METHODS: The cases (617 subjects) were all home-care workers in Sweden, whose disability pension was approved in 1997 or 1998. The controls (771 subjects) were home-care workers still working. We used a questionnaire to gain situation-specific information on working life and home life 5 and 15 years before disability pension entitlement. RESULTS: The most important risk factors in the work system were poor ergonomic/lifting conditions, time pressure and lack of professional caring technique. Fifteen years prior to disability pension entitlement, insufficient management (odds ratio (OR) 95%, CI 2.6[1.6;4.2]) and relational problems at work were also risk factors. Five years before disability pension entitlement, poor organisational support (4.1 [2.5;6.7]), opportunities for co-working and working climate (3.5 [2.4;5.2]) were also strongly related to a persisting work ability. The magnitude of exposure to a number of risk factors had an increased effect (highest 13.8 [5.6-33.8]). The strongest risk factor in home life was little opportunity to rest from work (4.9 [3.0;8.0]). The risk factors in working life were robust to the inclusion of the grouped risk factors of home life. CONCLUSIONS: The conclusion was that risk factors related to the work system are, alone, strongly related to permanent work disability among home-care workers. Also, exposure to several of the risk factors constitutes a notably strong risk for permanent work disability.
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| 19. |
- Hansson, Bengt, et al.
(författare)
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Restricted dispersal in a long-distance migrant bird with patchy distribution, the great reed warbler
- 2002
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 1432-1939 .- 0029-8549. ; 130:4, s. 536-542
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Tidskriftsartikel (refereegranskat)abstract
- In patchily distributed species dispersal connects local populations into metapopulations. Reliable quantifications of dispersal are therefore crucial to understanding the population dynamics and genetic structure of such metapopulation systems. The great reed warbler (Acrocephalus arundinaceus) inhabits eutrophic lakes and has a patchy breeding distribution. In this study we investigated the dispersal pattern of the great reed warbler based on an extensive capture-recapture effort covering a large census area (22,500 km(2)). At two adjacent breeding sites (10 km apart) in southern Central Sweden, the "main study area", we ringed the majority of adult and nestling great reed warblers between 1902 and 1999. In 1998 and 1999, we opportunistically searched for territorial males at the majority of the Swedish breeding sites, and were able to examine about 56% of all males in the region. Analyses of recaptured males demonstrated that philopatry predominated. Sixty-nine percent of the recruiting nestlings returned to breed in the main study area (their natal area), and 92% of the resighted adults were found at the same breeding locality in both study years. Breeding dispersal was significantly more restricted than natal dispersal. Additional data on natal and breeding dispersal within the main study area in 1992-1999 suggested that females were as philopatric as males. The overall high level of philopatry, with only occasional longer dispersal distances documented, yielded a root-mean-square dispersal distance of 33 km per generation. High philopatry, short dispersal distances and similar dispersal patterns of male and female great reed warblers contrast the findings among birds in general, but conform to data of species having patchy breeding habitat and isolated populations. Restricted dispersal suggests limited gene flow even among several Swedish populations, which is in line with some previous findings of the population ecology of the great reed warbler: (1) structured mtDNA lineages among European populations (2) small-scale population differences in song patterns; and (3) low genetic variation and occurrence of inbreeding depression in our main study population.
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| 20. |
- Lockwood, M, et al.
(författare)
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Coordinated Cluster and ground-based instrument observations of transient changes in the magnetopause boundary layer during an interval of predominantly northward IMF : relation to reconnection pulses and FTE signatures
- 2001
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 19:10-12, s. 1613-1640
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Forskningsöversikt (refereegranskat)abstract
- We study a series of transient entries into the low-latitude boundary layer (LLBL) of all four Cluster spacecraft during an outbound pass through the mid-afternoon magnetopause ([X(GSM), Y(GSM), Z(GSM)] approximate to [2, 7, 9] R(E)). The events take place during an interval of northward IMF, as seen in the data from the ACE satellite and lagged by a propagation delay of 75 min that is well-defined by two separate studies: (1) the magnetospheric variations prior to the northward turning (Lockwood et al., 2001, this issue) and (2) the field clock angle seen by Cluster after it had emerged into the magnetosheath (Opgenoorth et al., 2001, this issue). With an additional lag of 16.5 min, the transient LLBL events cor-relate well with swings of the IMF clock angle (in GSM) to near 90degrees. Most of this additional lag is explained by ground-based observations, which reveal signatures of transient reconnection in the pre-noon sector that then take 10-15 min to propagate eastward to 15 MLT, where they are observed by Cluster. The eastward phase speed of these signatures agrees very well with the motion deduced by the cross-correlation of the signatures seen on the four Cluster spacecraft. The evidence that these events are reconnection pulses includes: transient erosion of the noon 630 nm (cusp/cleft) aurora to lower latitudes; transient and travelling enhancements of the flow into the polar cap, imaged by the AMIE technique; and poleward-moving events moving into the polar cap, seen by the EISCAT Svalbard Radar (ESR). A pass of the DMSP-F15 satellite reveals that the open field lines near noon have been opened for some time: the more recently opened field lines were found closer to dusk where the flow transient and the poleward-moving event intersected the satellite pass. The events at Cluster have ion and electron characteristics predicted and observed by Lockwood and Hapgood (1998) for a Flux Transfer Event (FTE), with allowance for magnetospheric ion reflection at Alfvenic disturbances in the magnetopause reconnection layer. Like FTEs, the events are about 1 R(E) in their direction of motion and show a rise in the magnetic field strength, but unlike FTEs, in general, they show no pressure excess in their core and hence, no characteristic bipolar signature in the boundary-normal component. However, most of the events were observed when the magnetic field was southward, i.e. on the edge of the interior magnetic cusp, or when the field was parallel to the magnetic equatorial plane. Only when the satellite begins to emerge from the exterior boundary (when the field was northward), do the events start to show a pressure excess in their core and the consequent bipolar signature. We identify the events as the first observations of FTEs at middle altitudes.
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