| 1. |
- Wagner, J., et al.
(författare)
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First 230? : GHz VLBI fringes on 3C 279 using the APEX Telescope (Research Note)
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 581
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We report about a 230? GHz very long baseline interferometry (VLBI) fringe finder observation of blazar 3C 279 with the APEX telescope in Chile, the phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory (ARO). Methods. We installed VLBI equipment and measured the APEX station position to 1? cm accuracy (1σ). We then observed 3C 279 on 2012 May 7 in a 5? h 230? GHz VLBI track with baseline lengths of 2800? Mλ to 7200? Mλ and a finest fringe spacing of 28.6? μas. Results. Fringes were detected on all baselines with signal-to-noise ratios of 12 to 55 in 420? s. The correlated flux density on the longest baseline was ∼0.3? Jy beam-1, out of a total flux density of 19.8? Jy. Visibility data suggest an emission region ≤ 38? μas in size, and at least two components, possibly polarized. We find a lower limit of the brightness temperature of the inner jet region of about 1010? K. Lastly, we find an upper limit of 20% on the linear polarization fraction at a fringe spacing of ∼ 38? μas. Conclusions. With APEX the angular resolution of 230? GHz VLBI improves to 28.6? μas. This allows one to resolve the last-photon ring around the Galactic Center black hole event horizon, expected to be 40? μas in diameter, and probe radio jet launching at unprecedented resolution, down to a few gravitational radii in galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in detail, follow-up observations with APEX and five other mm-VLBI stations have been conducted (March 2013) and are being analyzed.
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| 2. |
- Roy, Alan, et al.
(författare)
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VLBI at APEX: First Fringes
- 2012
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Ingår i: Proceedings of Science. - 1824-8039. ; 2012-October
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Konferensbidrag (refereegranskat)
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| 3. |
- Zackrisson, Björn, et al.
(författare)
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Two-year results from a Swedish study on conventional versus accelerated radiotherapy in head and neck squamous cell carcinoma - The ARTSCAN study
- 2011
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Ingår i: Radiotherapy and Oncology. - : Elsevier. - 0167-8140 .- 1879-0887. ; 100:1, s. 41-48
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: Studies on accelerated fractionation (AF) in head and neck cancer have shown increased local control and survival compared with conventional fractionation (CF), while others have been non-conclusive. In 1998 a national Swedish group decided to perform a randomised controlled clinical study of AF. Materials and methods: Patients with verified squamous cell carcinoma of the oral cavity, oropharynx, larynx (except glottic T1-T2, N0) and hypopharynx were included. Patients with prior chemotherapy or surgery were excluded. Patients were randomised to either CF (2Gy/day, 5days/week for 7 weeks, total dose 68Gy) or to AF (1.1Gy+2.0Gy/day, 5days/week for 4.5weeks, total dose 68Gy). An extensive quality assurance protocol was followed throughout the study. The primary end point was loco-regional tumour control (LRC) at two years after treatment. RESULTS: The study was closed in 2006 when 750 patients had been randomised. Eighty-three percent of the patients had stages III-IV disease. Forty eight percent had oropharyngeal, 21% laryngeal, 17% hypopharyngeal and 14% oral cancers. There were no significant differences regarding overall survival (OS) or LRC between the two regimens. The OS at two years was 68% for AF and 67% for CF. The corresponding figures for LRC were 71% and 67%, respectively. There was a trend towards improved LRC for oral cancers treated (p=0.07) and for large tumours (T3-T4) (p=0.07) treated with AF. The AF group had significantly worse acute reactions, while there was no significant increase in late effects. Conclusion: Overall the AF regimen did not prove to be more efficacious than CF. However, the trend towards improved results in AF for oral cancers needs to be further investigated.
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| 4. |
- Callaghan, Terry, et al.
(författare)
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Multi-Decadal Changes in Tundra Environments and Ecosystems : Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:6, s. 705-716
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the responses of tundra systemsto global change has global implications. Most tundraregions lack sustained environmental monitoring and oneof the only ways to document multi-decadal change is toresample historic research sites. The International PolarYear (IPY) provided a unique opportunity for such researchthrough the Back to the Future (BTF) project (IPY project#512). This article synthesizes the results from 13 paperswithin this Ambio Special Issue. Abiotic changes includeglacial recession in the Altai Mountains, Russia; increasedsnow depth and hardness, permafrost warming, andincreased growing season length in sub-arctic Sweden;drying of ponds in Greenland; increased nutrient availabilityin Alaskan tundra ponds, and warming at mostlocations studied. Biotic changes ranged from relativelyminor plant community change at two sites in Greenland tomoderate change in the Yukon, and to dramatic increasesin shrub and tree density on Herschel Island, and in subarcticSweden. The population of geese tripled at one sitein northeast Greenland where biomass in non-grazed plotsdoubled. A model parameterized using results from a BTFstudy forecasts substantial declines in all snowbeds andincreases in shrub tundra on Niwot Ridge, Colorado overthe next century. In general, results support and provideimproved capacities for validating experimental manipulation,remote sensing, and modeling studies.
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| 5. |
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| 6. |
- Johansson, Jan-Ove, 1955, et al.
(författare)
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Growth hormone (GH) replacement in GH-deficient adults: a crossover trial comparing the effect on metabolic control, well-being and compliance of three injections per week versus daily injections.
- 2003
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Ingår i: Growth hormone & IGF research : official journal of the Growth Hormone Research Society and the International IGF Research Society. - 1096-6374. ; 13:6, s. 306-15
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Tidskriftsartikel (refereegranskat)abstract
- Growth hormone (GH) replacement therapy regimens in adults using daily subcutaneous (sc) injections may not be optimal with respect to carbohydrate and lipid metabolism. The aim of this study was to compare the efficacy of three times weekly injections with daily sc GH injections in terms of serum IGF-I, IGFBPs, lipoprotein levels, serum bone markers, glucose metabolism, body composition, compliance and well-being. Twenty hypopituitary men, 46-76 years, on a course of stable conventional GH replacement therapy for more than 12 months, were included in a 16-week crossover trial. During the first 8 weeks GH was administered three times per week followed by 8 weeks with daily sc injections with the same weekly dose of GH. Fasting serum samples were collected at baseline and on two consecutive days at the end of each 8-week period. Serum IGF-I and IGFBP-3 concentrations were lower both the first and second morning after the last injection during the period with three injections per week. The second morning after the last GH injection in this period the IGF-I/BP-3 ratio, plasma insulin and FFA were lower whereas IGFBP-1 was increased as compared with values obtained during the period with daily injections. Serum Lp(a) levels, body composition, fat distribution, well-being and compliance were not differently affected by the two treatment regimens. These results suggest that the same weekly dose of GH given as three injections per week reduces serum IGF-I and IGFBP-3 levels without affecting Lp(a) levels. The day-to-day variation in glucose metabolism and FFA serum levels differs considerably between the two modes of GH administration.
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| 7. |
- Nyberg, Jan, 1960-, et al.
(författare)
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Single-dose irradiation followed by implant insertion in rat bone : An investigative study to find a critical level for osseointegration
- 2010
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Ingår i: Journal of Osseointegration. - Carimate, Italy : Ariesdue. - 2036-4121. ; 2:2, s. 52-60
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Tidskriftsartikel (refereegranskat)abstract
- Aim: No general consensus exists regarding the ideal time to insert implants in bone after irradiation or how the various irradiation doses influence implant success. This study aims at investigating integration of implants in pre-irradiated rat bone and find a critical level doses that cause disturbed osseointegration.Materials and methods: Single irradiation doses of 2, 5, 10, 20 and 30 Gy were given to one leg of adult rats 3 days prior to insertion of screw-shaped implants whereas the other leg served as a non-irradiated control. The follow up was 5 weeks. Bone implant contact (BIC) and bone area (BA) were measured on undecalcified cut and ground sections in the light microscope. The tissue quality was also examined in the light microscope.Results: Doses of 5 and 10 Gy resulted in 25% higher contact values for the irradiated samples compared to non-irradiated controls. The most impaired integration occurred when doses of 20 Gy were given, revealing a 50% difference between the irradiated (25%) and the non irradiated samples (50%). The bone area demonstrated no major quantitative differences albeit the qualitative observations differed substantially being most pronounced in the 20 and 30 Gy irradiated samples.Conclusions: The osseointegration was substantially impaired after radiation doses of 20 and 30 Gy. Quantitative data alone are insufficient to describe implant integration in situation like this. Qualitative observations are of utmost importance and require great attention. The importance of judging and describing various grades of tissue damage is complicated but necessary. Based on the results obtained in this study, full scale experiments are now ongoing.
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| 8. |
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| 9. |
- Oscarsson, Jan, 1960, et al.
(författare)
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Two weeks of daily injections and continuous infusion of recombinant human growth hormone (GH) in GH-deficient adults. II. Effects on serum lipoproteins and lipoprotein and hepatic lipase activity.
- 1996
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Ingår i: Metabolism: clinical and experimental. - 0026-0495. ; 45:3, s. 370-7
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Tidskriftsartikel (refereegranskat)abstract
- Recombinant human growth hormone (GH) administered as daily subcutaneous (SC) injections has been shown to affect serum lipoproteins in GH-deficient subjects. However, the effects of continuous infusion of GH on serum lipoproteins have not been investigated in GH-deficient adults. The aim of the present study was to compare effects of daily injections and continuous infusion of GH on lipoprotein metabolism. Recombinant human GH (0.25 U/kg/wk) was administered to nine GH-deficient adult men during a period of 14 days in two different ways, ie, as a daily SC injection at 8:00 PM and as a continuous SC infusion, with 1 month of washout between the treatments. Blood samples and tests were performed in the morning after an overnight fast before the start of GH treatment (day 0) and on day 2 and day 14 of treatment. Abdominal SC adipose tissue lipoprotein lipase (LPL), postheparin plasma LPL, and hepatic lipase (HL) activity were measured 120 minutes after the intake of 100 g glucose. Adipose tissue LPL activity decreased and postheparin plasma HL activity increased after 14 days of GH treatment irrespective of the mode of GH administration, whereas GH treatment had no effect on postheparin plasma LPL activity. Serum triglyceride and very-low-density lipoprotein (VLDL) triglyceride concentrations increased during GH treatment. However, VLDL triglyceride concentrations increased to a greater degree during treatment with daily GH injections than during continuous infusion of GH. Serum apolipoprotein (apo) B and low-density lipoprotein (LDL) cholesterol concentrations decreased during treatment with daily GH injections, but were not significantly affected by continuous GH infusion. Thus, apo B and LDL cholesterol concentrations were lower after daily GH injections versus continuous GH infusion. Serum lipoprotein(a) [Lp(a)] and apo E concentrations increased during both modes of GH treatment. However, continuous infusion of GH resulted in a more marked increase in Lp(a) and apo E concentrations than daily GH injections. Minor effects were observed on serum apo A-I concentrations but high-density lipoprotein (HDL) cholesterol concentrations were not affected. In conclusion, GH treatment of GH-deficient men influenced adipose tissue LPL and postheparin plasma HL activity, as well as serum lipoprotein concentrations. Moreover, continuous GH infusion and daily GH injections differed with respect to the magnitude of effects on several lipoprotein fractions including VLDL triglycerides, LDL cholesterol, apo B, apo E, and Lp(a) concentrations.
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| 10. |
- Rosqvist, Fredrik, 1985-, et al.
(författare)
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Overeating saturated fat promotes fatty liver and ceramides compared to polyunsaturated fat : a randomized trial
- 2019
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : Oxford University Press. - 0021-972X .- 1945-7197. ; 104:12, s. 6207-6219
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Tidskriftsartikel (refereegranskat)abstract
- CONTEXT: Saturated fat (SFA) versus polyunsaturated fat (PUFA) may promote non-alcoholic fatty liver disease (NAFLD) by yet unclear mechanisms.OBJECTIVE: To investigate if overeating SFA- and PUFA-enriched diets lead to differential liver fat accumulation in overweight and obese humans.DESIGN: Double-blind randomized trial (LIPOGAIN-2). Overfeeding SFA vs PUFA for 8 weeks, followed by 4 weeks of caloric restriction.SETTING: General community.Participants: n=61 overweight or obese men and women.INTERVENTION: Muffins high in either palm (SFA)- or sunflower oil (PUFA) were added to the habitual diet.MAIN OUTCOME MEASURE: Lean tissue mass (not reported here). Secondary and exploratory outcomes included liver and ectopic fat depots.RESULTS: By design, body weight gain was similar in SFA (2.31±1.38 kg) and PUFA (2.01±1.90 kg) groups, P=0.50. SFA markedly induced liver fat content (50% relative increase) along with liver enzymes and atherogenic serum lipids. In contrast, despite similar weight gain, PUFA did not increase liver fat or liver enzymes or cause any adverse effects on blood lipids. SFA had no differential effect on the accumulation of visceral fat, pancreas fat or total body fat compared with PUFA. SFA consistently increased, while PUFA reduced circulating ceramides; changes that were moderately associated with liver fat changes and proposed markers of hepatic lipogenesis. The adverse metabolic effects of SFA were reversed by calorie restriction.CONCLUSIONS: Saturated fat markedly induces liver fat and serum ceramides whereas dietary polyunsaturated fat prevent liver fat accumulation, reduce ceramides and hyperlipidemia during excess energy intake and weight gain in overweight individuals.
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| 11. |
- Abel, Edvard, 1970, et al.
(författare)
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Impact on quality of life of IMRT versus 3-D conformal radiation therapy in head and neck cancer patients: A case control study
- 2017
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Ingår i: Advances in Radiation Oncology. - : Elsevier BV. - 2452-1094. ; 2:3, s. 346-353
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Tidskriftsartikel (refereegranskat)abstract
- Objective The purpose of this study was to prospectively and longitudinally compare the health-related quality of life (HRQOL) outcomes between head and neck (HN) cancer patients treated with parotid-sparing intensity modulated radiation therapy (IMRT) and patients treated with 3-dimensional conventional radiation therapy (3D-CRT). Methods and materials Before and up to 12 months after treatment, HRQOL was recorded in patients with HN cancer who were referred to the Department of Oncology at Sahlgrenska University Hospital for curative IMRT. The study group's HRQOL was compared with a matched group of patients from previous descriptive HRQOL studies treated with 3D-CRT. Both groups' HRQOL was measured by the European Organization for Research and Treatment for Cancer QLQ-C30 and European Organization for Research and Treatment for Cancer QLQ-HN35 at 6 time points in the first year after diagnosis. Results Two hundred and seven patients were included, 111 treated with IMRT and 96 matched controls treated with 3D-CRT. Both groups' HRQOL deteriorated during and after treatment. Just after treatment, worse HRQOL scores were observed in the IMRT group regarding insomnia (38 vs 27; P = .032), appetite loss (64 vs 50; P = .019), senses (54 vs 41; P = .017), and coughing (39 vs 26, P = .009). At 12 months, however, significantly better HRQOL scores were observed in the IMRT group regarding problems with dry mouth (72 vs 62; P = .018), pain (28 vs 20; P = .018), sexuality (37 vs 23; P = .016), social contacts (10 vs 6; P = .026), cognitive functioning (79 vs 87; P = .0057), and financial difficulties (12 vs 20; P = .0019). Conclusions This study further supports the hypothesis that the introduction of IMRT has improved the long-term quality of life of HN cancer patients who have been treated with radiation therapy, but might cause more acute side effects. Longer follow-up is needed to study late complications.
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| 12. |
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| 13. |
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| 14. |
- Alvestad, Torgeir, 1960, et al.
(författare)
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Challenges and dilemmas expressed by teachers working in toddler groups in the Nordic countries
- 2014
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Ingår i: Early Child Development and Care. - : Informa UK Limited. - 0300-4430 .- 1476-8275. ; 184:5, s. 671-688
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Tidskriftsartikel (refereegranskat)abstract
- This article is based on a collaborativestudy in Iceland, Sweden and Norway of the youngest children in institutional settings, such as preschools. At the present time, preschool curricula and frameworks are changing to include increased learning. However, preschool teacher education lacks sufficient focus on this age group. New preschool organisations depend both on the increased number of very young children in the system and on new versions of pedagogical approaches. This study is based on the voices of preschool staff who work with very young children. The results showed the dilemmas and challenges that these teachers experience in their everyday work.
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| 15. |
- Andrei, Constantin Octavian, et al.
(författare)
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Galileo l10 satellites: Orbit, clock and signal-in-space performance analysis
- 2021
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 21:5, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- The tenth launch (L10) of the European Global Navigation Satellite System Galileo filled in all orbital slots in the constellation. The launch carried four Galileo satellites and took place in July 2018. The satellites were declared operational in February 2019. In this study, we report on the performance of the Galileo L10 satellites in terms of orbital inclination and repeat period parameters, broadcast satellite clocks and signal in space (SiS) performance indicators. We used all available broadcast navigation data from the IGS consolidated navigation files. These satellites have not been reported in the previous studies. First, the orbital inclination (56.7 ± 0.15°) and repeat period (50680.7 ± 0.22 s) for all four satellites are within the nominal values. The data analysis reveals also 13.5-, 27-, 177-and 354-days periodic signals. Second, the broadcast satellite clocks show different correction magnitude due to different trends in the bias component. One clock switch and several other minor correction jumps have occurred since the satellites were declared operational. Short-term discontinuities are within ±1 ps/s, whereas clock accuracy values are constantly below 0.20 m (root-mean-square—rms). Finally, the SiS performance has been very high in terms of availability and accuracy. Monthly SiS availability has been constantly above the target value of 87% and much higher in 2020 as compared to 2019. Monthly SiS accuracy has been below 0.20 m (95th percentile) and below 0.40 m (99th percentile). The performance figures depend on the content and quality of the consolidated navigation files as well as the precise reference products. Nevertheless, these levels of accuracy are well below the 7 m threshold (95th percentile) specified in the Galileo service definition document.
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| 16. |
- Andrei, Constantin Octavian, et al.
(författare)
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Signal performance analysis of the latest quartet of Galileo satellites during the first operational year
- 2020
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Ingår i: 2020 International Conference on Localization and GNSS, ICL-GNSS 2020 - Proceedings.
-
Konferensbidrag (refereegranskat)abstract
- On 12 February 2020, the latest four Galileo satellites had completed one full year of space operational service. The satellites were launched on 25 July 2018. The quartet increased the operational capacity of the Galileo constellation to 22 satellites. This study reports on three signal-in-space (SiS) performance indicators - status, availability, and ranging accuracy - from 11 February 2019 to 12 February 2020. In addition, the study looks also at how the on-board satellite clocks have performed. The data analysis shows 100% data validity and signal health status for three our of the four satellites, whereas NAPA (No Accuracy Prediction Available) events accounted for about 2% of the time. In addition, SiS availability was higher than 95% in the first operational year. Furthermore, the 95th percentile of the global average of the instantaneous signal in space error is found to vary between 0.17 to 0.33 m on monthly basis. Lastly, the precise satellite clock biases show high short-term performance with 0.1 ps/s (10-13 s/s) standard deviations during the first operational year. The numerical results indicate a robust performance and high reliability for the youngest Galileo satellites in the constellation. They increase the number of operational satellites in the constellation and thus contribute to the Galileo's increased popularity in the satellite-based positioning and navigation user community.
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| 17. |
- Bergstrand, Sten, 1971, et al.
(författare)
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BIFROST: Noise properties of GPS time series
- 2007
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Ingår i: in "Dynamic Planet: Monitoring and Understanding a Dynamic Planet with Geodetic and Oceanographic Tools", IAG Symposium, Cairns, Australia, 22-26 August, 2005, Series: International Association of Geodesy Symposia , Vol. 130, Tregoning, Paul; Rizos, Chris (Eds.), Springer. - 9783540493495 ; 130, s. 123-130
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Konferensbidrag (refereegranskat)
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| 18. |
- Bergstrand, Sten, 1971, et al.
(författare)
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Ionospheric Corrections for Accurate Positioning in Real Time
- 2005
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Ingår i: in Proc. Radio Science and Communication (RVK), eds. O. Gustafsson, P. Löwenborg, Linköping, Sweden, June 14-16, 2005. - 9170561222 ; , s. 391-394
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 19. |
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| 20. |
- Boström, Pontus, 1982, et al.
(författare)
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SNARE proteins mediate fusion between cytosolic lipid droplets and are implicated in insulin sensitivity.
- 2007
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Ingår i: Nature cell biology. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 9:11, s. 1286-93
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Tidskriftsartikel (refereegranskat)abstract
- The accumulation of cytosolic lipid droplets in muscle and liver cells has been linked to the development of insulin resistance and type 2 diabetes. Such droplets are formed as small structures that increase in size through fusion, a process that is dependent on intact microtubules and the motor protein dynein. Approximately 15% of all droplets are involved in fusion processes at a given time. Here, we show that lipid droplets are associated with proteins involved in fusion processes in the cell: NSF (N-ethylmaleimide-sensitive-factor), alpha-SNAP (soluble NSF attachment protein) and the SNAREs (SNAP receptors), SNAP23 (synaptosomal-associated protein of 23 kDa), syntaxin-5 and VAMP4 (vesicle-associated membrane protein 4). Knockdown of the genes for SNAP23, syntaxin-5 or VAMP4, or microinjection of a dominant-negative mutant of alpha-SNAP, decreases the rate of fusion and the size of the lipid droplets. Thus, the SNARE system seems to have an important role in lipid droplet fusion. We also show that oleic acid treatment decreases the insulin sensitivity of heart muscle cells, and this sensitivity is completely restored by transfection with SNAP23. Thus, SNAP23 might be a link between insulin sensitivity and the inflow of fatty acids to the cell.
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| 21. |
- Buvall, Lisa, 1976, et al.
(författare)
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Orellanine specifically targets renal clear cell carcinoma
- 2017
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Ingår i: Oncotarget. - : Impact Journals, LLC. - 1949-2553. ; 8:53, s. 91085-91098
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Tidskriftsartikel (refereegranskat)abstract
- Renal cell carcinoma (RCC), arising from the proximal tubule in the kidney, accounts for approximately 85% of kidney cancers and causes over 140,000 annual deaths worldwide. In the last decade, several new therapies have been identified for treatment of metastatic RCC. Although these therapies increase survival time compared to standard care, none of them has curative properties. The nephrotoxin orellanine specifically targets proximal tubular epithelial cells, leaving other organs unaffected. We therefore hypothesized that the selective toxicity of orellanine extends to clear cell RCC (ccRCC) cells since they emanate from proximal tubular cells. Orellanine would thus target both primary and metastatic ccRCC in vitro and in vivo. We found that orellanine induces dose-dependent cell death in proximal tubular cells and in all ccRCC cells tested, both primary and cell lines, with no toxicity detected in control cells. The toxic action of orellanine involve decreased protein synthesis, disrupted cell metabolism and induction of apoptosis. In nude rats carrying human ccRCC xenografts, brief orellanine treatment eliminated more than 90% of viable tumor mass compared to control rats. This identifies orellanine as a potential treatment concept for ccRCC patients on dialysis, due to its unique selective toxicity towards ccRCC.
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| 22. |
- Dutta, Uttama, 1979, et al.
(författare)
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Ionospheric Effects on GNSS RTK
- 2022
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Ingår i: 35th International Technical Meeting of the Satellite Division of the Institute of Navigation, ION GNSS+ 2022. - : Institute of Navigation. ; 3, s. 1557-1566
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Konferensbidrag (refereegranskat)abstract
- GNSS signals are influenced by free electrons as they propagate through the ionosphere. Studies have shown how the spatial variations of electron density in the ionosphere, affects measurements with network-Real Time Kinematic (NRTK) (Emardson et al 2011). This paper aims to predict what can be expected from measurements during the next solar maximum that is expected to occur around 2025 and discusses how it would affect RTK for automated transport applications. The ionospheric activity and its impact on positioning in the coming solar cycle maximum is discussed. This study focuses on data from Kiruna in northern Sweden (67.8N), mainly captured in January 2014 - in the middle of the most active time during the last cycle - which has been analyzed to predict the coming solar cycle. Based on the data, it was concluded that there is a risk of occasions with simultaneous signal slips on several satellites caused by the ionosphere which could cause temporary (minutes) loss of positioning ability for the RTK equipment. It is expected to occur a couple of times per month during the most active months of the solar cycle.
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| 23. |
- Dutta, Uttama, 1979, et al.
(författare)
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Multi-Constellation/Multi-Frequency GNSS Signal Degradation Due to Foliage and Reflective Environments †
- 2023
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Ingår i: Engineering Proceedings. - 2673-4591. ; 54:1
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Tidskriftsartikel (refereegranskat)abstract
- Present day GNSS offers a variety of signals from different satellite constellations and at various frequencies. This paper is based on the work conducted in the project SiL 2.0 and will focus on the study of multi-constellation/multi-frequency GNSS signals as received on top of construction equipment as part of the SiL 2.0 dissemination solution. This paper aims to study the impact of foliage and reflective environments on the various signals of multi-constellation GNSS with a focus on GPS and Galileo. Signal strength indicators (SSI) have been used as a measure to understand the shadowing environment around a stationary GNSS antenna mounted on an excavator. It is quite clear from the analysis that traditional GPS L2 signals, C2W and L2W, are weaker in strength than the L2C and L1 C/A signals, and this is found to be consistent for all of the GPS satellites. The effect of signal degradation due to bending over sharp metallic edges is also discussed.
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| 24. |
- Ebenhag, Sven-Christian, 1976, et al.
(författare)
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Fiber based one-way time transfer with enhanced accuracy
- 2010
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Ingår i: 24th European Frequency and Time Forum, EFTF 2010; Noordwijk; Netherlands; 13 April 2010 through 16 April 2010. - 9781467359702
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Konferensbidrag (refereegranskat)abstract
- To meet the request for access to accurate and reliable time, several time and frequency transfer methodsusing optical fibers have been developed or are under development. These fiber based techniques willovercome the issues of vulnerability in radio- and satellite solutions; however, they all rely on two-waytransmission when variations in transfer time must be compensated for. As an alternative, a one-waytransmission over fiber optic WDM-network has been proposed, with estimation of variation in transfertime based on detection of transfer time difference between two co-propagating lightwaves at differentwavelengths. The technique was presented previously when the two wavelengths were far apart. Here wepresent results from an experiment where both wavelengths are within the optical C-band, i.e. within thegain bandwidth of Erbium-doped fiber amplifiers. Thereby it is proven that the technique is usable to alarger extent than previously demonstrated.
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| 25. |
- Ebenhag, Sven-Christian, 1976, et al.
(författare)
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Time transfer using an asynchronous computer network: Results from three weeks of measurements
- 2007
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Ingår i: European Frequency and Time Forum, 29/5 - 1/6, Geneva, CH.
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Konferensbidrag (refereegranskat)abstract
- We have performed a time transfer experimentbetween two atomic clocks, over a distance of approximately 75km using an 10 Gbit/s asynchronous fiber-optic computernetwork. The time transfer was accomplished through passivelistening on existing data traffic and a pilot sequence in the SDHbit stream. In order to assess the fiber-link clock comparison, wesimultaneously compared the clocks using a GPS carrier phaselink. The standard deviation of the difference between the twotime transfer links over the three-week time period was 243 ps.
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Elgered, Gunnar, 1955, et al.
(författare)
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GNSS for global environmental Earth observation
- 2013
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- This booklet is produced within the Gfg2 project, a three year coordination action, funded by the 7th Framework Program of the European Commission under the Environment theme. Its mission is to better assess the value of Global Navigational Satellite Systems (GNSS) for Global Environmental Earth Observation (GEEO) and GEOSS.
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| 30. |
- Elgered, Gunnar, 1955, et al.
(författare)
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GNSS för globala jordobservationer
- 2014
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Detta häfte har producerats av Gfg2-projektet, en treårig koordineringsaktivitet finansierad av Europeiska kommissionens sjunde ramprogram inom dess miljötema. Projektets uppgift är att belysa värdet av jordobservationer med hjälp av globala navigationssystem (GNSS = Global Navigational Satellite Systems) för Global Environmental Earth Observation (GEEO) och Global Earth Observation System of Systems (GEOSS).
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| 31. |
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| 32. |
- Elgered, Gunnar, 1955, et al.
(författare)
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Measuring regional atmospheric water vapor using the Swedish permanent GPS network
- 1997
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Ingår i: Geophysical Research Letters. - 1944-8007 .- 0094-8276. ; 24:21, s. 2663-2666
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the application of a geodetic network of ground-based GPS receivers in Sweden to the measurement of atmospheric water vapor. Using data acquired during four days in December 1993, we show that it is possible to study the detailed motions of air mass systems. Estimates of water vapor from GPS data agree with those from radiosonde and microwave radiometer data to within 1 mm RMS.
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| 33. |
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| 34. |
- Elgered, Gunnar, 1955, et al.
(författare)
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Validation of climate models using European ground-based GNSS observations
- 2009
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Ingår i: Proc. of 2nd Colloquium Scientific and Fundamental Aspects of the Galileo Programme, European Space Agency, 15-19 October, 2009, Padua, Italy. ; CD ROM
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We summarize an ongoing research project where we assess the quality of time series of the Integrated Water Vapour in the atmosphere estimated from ground-based GNSS data for the application of validating and possibly improving climate models. The focus is on the factors limiting the accuracy and especially the long-term stability of the GNSS technique.Higher order ionospheric corrections have been studied, using realistic values for the Total Electron Content (TEC) close to the solar maximum in 2002. Averaged over ten days we find that the impact in the mean IWV is less than 0.1 kg/m^2. Another factor is the model used for antenna phase centre variations. We have studied this effect on the IWV estimates by simulations and by studying estimates of the IWV based on observed GPS signals. We find that ignoring satellite antenna phase variations, when processing GPS data from 2003-2008, can significantly influence the values of the estimated linear trends. The value depends on the latitude of the site as well as on the elevation cut-off angle used in the data analysis. Finally, we show a significant correlation between estimated linear trends in the IWV and the corresponding linear trends in the independently observed ground temperature.
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| 35. |
- Emardson, Ragne, 1969, et al.
(författare)
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GROUND- AND SATELLITE- BASED GNSS MEASUREMENTS OF WATER VAPOUR WITH FOCUS ON CLIMATE APPLICATIONS
- 2014
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Ingår i: Proceedings of Metrology for Meteorology and Climate 2014 conference.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Water vapour is one of the most important green-house gases and the amount of water vapor in the atmosphere is an important indicator for climate change. Due to its high variability, irregular height distribution and poor mixing with other constituents, accurate measurements of water vapour in the atmosphere are difficult and costly to carry out with high temporal and spatial resolution over long time. The delay of Global Navigation Satellite Systems (GNSS) signals when propagating through the atmosphere due to the presence of water vapour is nearly proportional to the quantity of water vapour integrated along the signal path. Hence, using ground-based GNSS receiver networks it is possible to measure the signal delay in the atmosphere, which in turn can be used to derive the atmospheric water vapour content, the Integrated Water Vapour (IWV). Since time interval measurements can be traceable to standards, it is a promising method for providing an observational system for climate monitoring. However, in order to make a proper uncertainty assessment of the measured water vapour, the different error sources affecting the measurements need to be controlled. GNSS occultation measurements are obtained by deploying GNSS receivers onboard Low Earth Orbit (LEO) satellites. The main observable in GNSS occultation measurements is the Doppler shift of the received signal phase. Based on the Doppler shift the vertical profile of the refractive index can be inferred. From the refractive index measurements, we can estimate temperature, pressure, and the amount of water vapour. A key issue in using occultation measurement for climate purposes lies in the methodology of making the measured parameters traceable to references. Here, we present new methods of using booth ground-based and satellite-based GNSS measurements for climate studies. We have used 6 months of GNSS measurements collected both from ground-based networks and from receivers deployed on satellites.
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| 36. |
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Eriksson, Jan W., et al.
(författare)
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Hydrochlorothiazide, but not Candesartan, aggravates insulin resistance and causes visceral and hepatic fat accumulation : the mechanisms for the diabetes preventing effect of Candesartan (MEDICA) Study
- 2008
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Ingår i: Hypertension. - : American Heart Association. - 0194-911X .- 1524-4563. ; 52:6, s. 1030-1037
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Tidskriftsartikel (refereegranskat)abstract
- Treatment with angiotensin II receptor blockers is associated with lower risk for the development of type 2 diabetes mellitus compared with thiazide diuretics. The Mechanisms for the Diabetes Preventing Effect of Candesartan Study addressed insulin action and secretion and body fat distribution after treatment with candesartan, hydrochlorothiazide, and placebo. Twenty-six nondiabetic, abdominally obese, hypertensive patients were included in a multicenter 3-way crossover trial, and 22 completers (by predefined criteria; 10 men and 12 women) were included in the analyses. They underwent 12-week treatment periods with candesartan (C; 16 to 32 mg), hydrochlorothiazide (H; 25 to 50 mg), and placebo (P), respectively, and the treatment order was randomly assigned and double blinded. Intravenous glucose tolerance tests and euglycemic hyperinsulinemic (56 mU/m(2) per minute) clamps were performed. Intrahepatic and intramyocellular and extramyocellular lipid content and subcutaneous and visceral abdominal adipose tissue were measured using proton magnetic resonance spectroscopy and MRI. Insulin sensitivity (M-value) was reduced following H versus C and P (6.07+/-2.05, 6.63+/-2.04, and 6.90+/-2.10 mg/kg of body weight per minute, mean+/-SD; P
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| 41. |
- Fornell, Jan, et al.
(författare)
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Flapless, CBCT-guided osteotome sinus floor elevation with simultaneous implant installation. I: radiographic examination and surgical technique. A prospective 1-year follow-up.
- 2012
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Ingår i: Clinical oral implants research. - : Wiley. - 1600-0501 .- 0905-7161. ; 23:1, s. 28-34
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Tidskriftsartikel (refereegranskat)abstract
- Background: Survival rates of implants placed in transalveolar sinus floor augmentation sites are comparable with those placed in non-augmented sites. Flapless implant surgery can minimize postoperative morbidity, alveolar bone resorption and crestal bone loss. The use of cone beam computerized tomography (CBCT) provides 3D presentations with reduced dose exposure. Objectives: To evaluate a flapless, CBCT-guided transalveolar sinus floor elevation technique with simultaneous implant installation. Material and methods: Fourteen consecutive patients in need of maxillary sinus floor augmentation were enrolled in this study. Preoperative CBCT with a titanium screwpost as an indicator at the intended implant position was used to visually guide the flapless surgical procedure. Twenty one implants all with a length of 10mm and a diameter of 4.1 and 4.8mm were inserted and followed clinically and with CBCT for 3, 6 and 12 months postoperatively. Intraoral radiographs were taken for comparison. All patients were provided with permanent prosthetic constructions 8-12 weeks after implant surgery. Results: Ten (47.6%) implants were inserted in residual bone of 2.6-4.9mm and 11 (52.3%) implants were inserted in residual bone of 5-8.9mm. No implants were lost after surgery and follow-up. There was no marginal bone loss during the follow-up verified by CBCT. The implants penetrated on average 4.4mm (SD 2.1mm) into the sinus cavity and the mean bone gain was 3mm (SD 2.1mm). Conclusion: Flapless transalveolar sinus lift procedures visually guided by preoperative CBCT can successfully be used to enable placement, successful healing and loading of one to three implants in residual bone height of 2.6-8.9mm. There was no marginal bone loss during the 3-12 months follow-up. To cite this article: Fornell J, Johansson L-Å, Bolin A, Isaksson S, Sennerby L. Flapless, CBCT-guided osteotome sinus floor elevation with simultaneous implant installation. I: radiographic examination and surgical technique. A prospective 1-year follow-up. Clin. Oral Impl. Res. xx, 2011; 000-000. doi: 10.1111/j.1600-0501.2010.02151.x.
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| 42. |
- Glimaker, M., et al.
(författare)
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Early lumbar puncture in adult bacterial meningitis-rationale for revised guidelines
- 2013
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Ingår i: Scandinavian Journal of Infectious Diseases. - : Informa UK Limited. - 0036-5548 .- 1651-1980. ; 45:9, s. 657-663
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Tidskriftsartikel (refereegranskat)abstract
- Current international guidelines recommend cerebral computerized tomography (CT) before lumbar puncture (LP) in many adults with suspected acute bacterial meningitis (ABM), due to concern about LP-induced cerebral herniation. Despite guideline emphasis on early treatment based on symptoms, performing CT prior to LP implies a risk of delayed ABM treatment, which may be associated with a fatal outcome. Firm evidence for LP-induced herniation in adult ABM is absent and brain CT cannot discard herniation. Thus, the recommendation to perform CT before LP may contribute to an avoidable delay of LP and ABM treatment. The inappropriate use of the diagnostic treatment sequence of brain CT scan, followed by LP, followed by antibiotics and corticosteroids should be avoided in adults with suspected ABM by omitting needless contraindications for LP, thus eliminating an unnecessary fear of immediate LP. Revised Swedish guidelines regarding early LP are presented, and the background documentation and reasons for omitting impaired consciousness, new onset seizures, and immunocompromised state as contraindications to LP are discussed.
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| 43. |
- Granström, Camilla, 1978, et al.
(författare)
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The Influence of Vegetation and Multipath on GNSS Signals
- 2005
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Ingår i: in Proc. Radio Science and Communication (RVK), Linköping, Sweden, June 14-16, 2005, eds. O. Gustafsson, P. Löwenborg. - 9170561222 ; , s. 385-390
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 44. |
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| 45. |
- Gustafsson Nyckel, Jan, 1960-, et al.
(författare)
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Travelling and Recontextualization of Discourses on Quality in Early Childhood Education and Care : A Meta-Ethnographic Investigation
- 2023
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Ingår i: Oxford Ethnography and Education Conference 2023. ; , s. 1-1
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This article is a response to the need for comparative and critical studies of preschool as a local practice and examines the recontextualization of quality in Early childhood education and care. The aim of this meta-ethnographic study is to investigate how neoliberal policy discourses on quality are recontextualized and embedded in local early childhood and care institutional practices. A central concept in the analysis is recontextualization, and our pre-understanding of how neoliberal policy discourses are travelling and transformed from official to local policy that is embedded in the preschools’ work with quality as an institutional practice.The findings show how neoliberal policy discourses on quality is recontextualized, transformed and embedded in local institutional practices with different results and responses. The analysis uncovers three strategic, institutional responses as Enacting through acquiescence response, Defiance response as resistance and obfuscation of class, gender, and post-colonial perspective.
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| 46. |
- Haas, Rüdiger, 1966, et al.
(författare)
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An Investigation of Water Vapor Trends in Europe
- 2005
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Ingår i: in “Proc. of the 17'th Working Meeting on European VLBI for Geodesy and Astrometry”, eds. M. Vennebusch, A. Nothnagel. ; , s. 91-96
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 47. |
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| 48. |
- Haas, Rüdiger, 1966, et al.
(författare)
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Contributions of Onsala Space Observatory to GGOS
- 2015
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Ingår i: Proceedings of the 22nd European VLBI Group for Geodesy and Astrometry Working Meeting. - 9789892061917 ; , s. 125-129
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 49. |
- Haas, Rüdiger, 1966, et al.
(författare)
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Periodic station motion in Gothenburg observed with GPS - possibily related to hydrological phenomena?
- 2009
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Ingår i: Advances in Geosciences: Volume 13: Solid Earth (SE). - : World Scientific Publishing Co. Pte. Ltd.. - 9789812836175 ; 13:Solid Earth, s. 181-192
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- We analyze several years of GPS data recorded with roof-top stations in Gothenburg (Sweden) and permanent stations of the Swedish national reference network in the larger Gothenburg region. The derived station positions of several of the roof-top stations in Gothenburg reveal periodic horizontal motions with amplitudes of several millimeters and periodic vertical motions with amplitudes of up to 1.5 mm. The observed motions have primarily an annual period. We compare the GPS-derived station motions with hydrological information (ground water and river level) and meteorological information (air temperature and pressure). The results indicate that the GPS-detected motions might be related to hydrological phenomena.
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| 50. |
- Hambraeus, Kristina, et al.
(författare)
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SWEDEHEART annual report 2012
- 2014
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Ingår i: Scandinavian Cardiovascular Journal. - : Informa Healthcare. - 1401-7431 .- 1651-2006. ; 48:SUPPL. 63, s. 1-333
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Web-system for Enhancement and Development of Evidence-based care in Heart disease Evaluated According to Recommended Therapies (SWEDEHEART) supports continuous monitoring and improvement of care for coronary artery disease, catheter-based and surgical coronary interventions, secondary prevention as well as catheter based and surgical valve intervention, by providing extensive data on base-line, diagnostic, procedural and outcome variables. Design. This national quality registry collects information from all Swedish hospitals treating patients with acute coronary artery disease and all patients undergoing coronary angiography, catheter-based interventions or heart surgery. Combination with other national mandatory official registries enables complete follow-up of all individuals regarding myocardial infarction, new interventional procedures, death and all-cause hospitalizations. The registry is governed by an independent steering committee and funded by the Swedish National Health care provider. The software is developed by Uppsala Clinical Research Center. Results. The SWEDEHEART Quality Index reflects overall quality of care for coronary artery disease including secondary prevention. In comparison with 2011, an improvement of the index occurred in 2012 overall. There was however, still a wide range in performance between individual centers, emphasizing the need for continuous monitoring of quality of care at a national as well as on a center level. © 2014 Informa Healthcare.
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