| 1. |
- Andersen, Christen Lykkegaard, et al.
(författare)
-
Circulating YKL-40 in patients with essential thrombocythemia and polycythemia vera treated with the novel histone deacetylase inhibitor vorinostat
- 2014
-
Ingår i: Leukemia Research. - : Elsevier. - 0145-2126 .- 1873-5835. ; 38:7, s. 816-821
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Tidskriftsartikel (refereegranskat)abstract
- YKL-40 regulates vascular endothelial growth factors and induces tumor proliferation. We investigated YKL-40 before and after treatment with vorinostat in 31 polycythemia vera (PV) and 16 essential thrombocythemia (ET) patients. Baseline PV patient levels were 2 times higher than in healthy controls (P<0.0001) and 1.7 times higher than in ET (P = 0.02). A significant correlation between YKL-40 at baseline and neutrophils, CRP, LDH, JAK2V617F and platelets in PV patients was observed, as well as a significantly greater reduction of YKL-40 levels in PV patients responding to therapy. YKL-40 might be a novel marker of disease burden and progression in myeloproliferative neoplasms.
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| 2. |
- Andersen, Torben, et al.
(författare)
-
Euro50
- 2003
-
Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 5382:1, s. 169-182
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Konferensbidrag (refereegranskat)abstract
- The Euro50 is a telescope for optical and infrared wavelengths. It has an aspherical primary mirror with a size of 50 meters and 618 segments. The optical configuration is of Gregorian type and the secondary mirror is deformable for adaptive optics. Observations can take place in prime focus, Gregorian foci, and Nasmyth foci using additional relay mirrors. The telescope provides seeing limited observations, partial adaptive optics with ground layer correction, single conjugate adaptive optics and dual-conjugate adaptive optics. For prime focus observations, a clam-shell corrector with a doublet lens is used. The primary mirror segments can be polished using the precessions polishing technique. "Live Optics" denotes the joint segment alignment system, secondary mirror control system, adaptive optics and main axes servos. An overview is given of the live optics architecture, including feedback from wavefront sensors for natural and laser guide stars, and from primary mirror segment edge sensors. A straw man concept of the laser guide star system using sum-frequency YAG lasers is presented together with a solution to the laser guide star perspective elongation problem. The structural design involves a large steel structure and a tripod of carbon fiber reinforced polymer to support the secondary mirror. Integrated models have been set up to simulate telescope performance. Results show that an enclosure is needed to protect the telescope against wind during observations. The enclosure is very large box-shaped steel structure
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| 3. |
- Andersen, Torben, et al.
(författare)
-
Integrated modeling of the Euro50
- 2003
-
Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5382:1, s. 366-378
-
Konferensbidrag (refereegranskat)abstract
- The Euro50 is a proposed 50 m optical and infrared telescope. It will have thousands of control loops to keep the optics aligned under influence of wind, gravity and thermal loads. Cross-disciplinary integrated modeling is used to study the overall performance of the Euro50. A sub-model of the mechanical structure originates from finite element modeling. The optical performance is determined using ray tracing, both non-linear and linearized. The primary mirror segment alignment control system is modeled with the 618 segments taken as rigid bodies. Adaptive optics is included using a layered model of the atmosphere and sub-models of the wavefront sensor, reconstructor and controller. The deformable mirror is, so far, described by a simple influence function and a second order dynamical transfer function but more detailed work is in progress. The model has been implemented using Matlab/Simulink on individual computers but it will shortly be implemented on a Beowulf cluster within a trusted network. Communication routines between Matlab on the cluster processors have been written and are being benchmarked. Representative results from the simulations are shown
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| 4. |
- Beckers, Jacques M., et al.
(författare)
-
Sodium beacon wavefront sensing for the Euro50 telescope in the presence of perspective elongation
- 2004
-
Ingår i: Proceedings of the SPIE. - : SPIE. - 0819452998 ; 5382, s. 510-519
-
Konferensbidrag (refereegranskat)abstract
- To obtain full sky coverage, astronomical adaptive optics systemsrequire Na Sodium Beacons (SBs) (also referred to as Laser Guide Starsor LGSs) located at heights extending from 85 to 100 km. When viewed atthe edge of large telescopes these SBs appear elongated. For the Euro5050 meter aperture telecopes this elongation amounts to 6 to 9 arcsecondswhen the laser is launched from a point on the telescope axis. This issubstantially larger than the -0.6 arcsec FWHM SB when viewed near thetelescope center. This so-called "perspective elongation" substantiallydecreases the sensitivity of SB aided adaptive optics. We describe a wayof removing this elongation when using pulsed lasers. It uses rapid(microsecond) refocusing of the telescope with the aid of birefringentlenses and polarization modulators. We present an outline of the SBwavefront sensor for the Euro50.
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| 5. |
- Enmark, Anita, et al.
(författare)
-
Modeling ELTs at different wavelengths
- 2008
-
Ingår i: Extremely Large Telescopes: Which Wavelengths? Retirement Symposium for Arne Ardeberg. - : SPIE. - 0277-786X .- 1996-756X. ; 6986, s. 9860-9860
-
Konferensbidrag (refereegranskat)abstract
- The next generation of telescopes, the Extremely Large Telescopes (ELTs), will have a multitude Of control loops to maintain nearly diffraction-limited performance in the presence of atmospheric turbulence and external disturbances, for instance from wind. Integrated simulation models combining structural and optical modeling together with control system modeling are efficient tools for prediction of performance of ELTs. Such models include submodels of structures, adaptive optics, atmosphere, wind load, deformable mirrors and a segmented primary mirror. So far the models applied have been applicable to observations in the K-band. However, there is a desire to also operate the ELTs with adaptive optics at wavelengths in the visible range. We here give estimates of the feasibility of performing such simulations. We set up scaling laws for the design parameters as a function of wavelength of operation and we show that the execution time for an integrated model of an ELT depends dramatically on the operation wavelength. We also discuss the consequences of different choices of model refinement. Finally we present estimates of the execution time for integrated models of ELTs. We show that accurate modeling in the K-band calls for long execution times, even with parallel computers. For wavelengths in the visible range, only the very simplest models are feasible due to execution time limitations, thereby precluding many interesting studies related to noise sensitivity and limiting magnitude for guide stars.
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| 6. |
- Helgadottir, Anna, et al.
(författare)
-
The same sequence variant on 9p21 associates with myocardial infarction, abdominal aortic aneurysm and intracranial aneurysm
- 2008
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:2, s. 217-224
-
Tidskriftsartikel (refereegranskat)abstract
- Recently, two common sequence variants on 9p21, tagged by rs10757278-G and rs10811661-T, were reported to be associated with coronary artery disease (CAD)(1-4) and type 2 diabetes (T2D)(5-7), respectively. We proceeded to further investigate the contributions of these variants to arterial diseases and T2D. Here we report that rs10757278-G is associated with, in addition to CAD, abdominal aortic aneurysm (AAA; odds ratio (OR) 1.31, P = 1.2 x 10(-12)) and intracranial aneurysm (OR = 1.29, P = 2.5 x 10(-6)), but not with T2D. This variant is the first to be described that affects the risk of AAA and intracranial aneurysm in many populations. The association of rs10811661-T to T2D replicates in our samples, but the variant does not associate with any of the five arterial diseases examined. These findings extend our insight into the role of the sequence variant tagged by rs10757278-G and show that it is not confined to atherosclerotic diseases.
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| 7. |
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| 8. |
- Andersen, Christen L., et al.
(författare)
-
A phase II study of vorinostat (MK-0683) in patients with polycythaemia vera and essential thrombocythaemia
- 2013
-
Ingår i: British Journal of Haematology. - : Wiley. - 0007-1048 .- 1365-2141. ; 162:4, s. 498-508
-
Tidskriftsartikel (refereegranskat)abstract
- Inhibition of histone deacetylases may be an important target in patients with myeloproliferative neoplasms. This investigator-initiated, non-randomized, open-label phase II multi-centre study included 63 patients (19 essential thrombocythaemia, 44 polycythaemia vera) from 15 centres. The primary objective was to evaluate if vorinostat was followed by a decline in clonal myeloproliferation as defined by European Leukaemia Net. Thirty patients (48%) completed the intervention period (24 weeks of therapy). An intention-to-treat response rate of 35% was identified. Pruritus was resolved [19% to 0% (P=0.06)] and the prevalence of splenomegaly was lowered from 50% to 27% (P=0.03). Sixty-five per cent of the patients experienced a decrease in JAK2 V617F allele burden (P=0.006). Thirty-three patients (52% of patients) discontinued study drug before end of intervention due to adverse events (28 patients) or lack of response (5 patients). In conclusion, vorinostat showed effectiveness by normalizing elevated leucocyte and platelet counts, resolving pruritus and significantly reducing splenomegaly. However, vorinostat was associated with significant side effects resulting in a high discontinuation rate. A lower dose of vorinostat in combination with conventional and/or novel targeted therapies may be warranted in future studies.
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| 9. |
- Benzinou, Michael, et al.
(författare)
-
Common nonsynonymous variants in PCSK1 confer risk of obesity.
- 2008
-
Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:8, s. 943-5
-
Tidskriftsartikel (refereegranskat)abstract
- Mutations in PCSK1 cause monogenic obesity. To assess the contribution of PCSK1 to polygenic obesity risk, we genotyped tag SNPs in a total of 13,659 individuals of European ancestry from eight independent case-control or family-based cohorts. The nonsynonymous variants rs6232, encoding N221D, and rs6234-rs6235, encoding the Q665E-S690T pair, were consistently associated with obesity in adults and children (P = 7.27 x 10(-8) and P = 2.31 x 10(-12), respectively). Functional analysis showed a significant impairment of the N221D-mutant PC1/3 protein catalytic activity.
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| 10. |
- Chen, Wei-Min, et al.
(författare)
-
Variations in the G6PC2/ABCB11 genomic region are associated with fasting glucose levels.
- 2008
-
Ingår i: Journal of Clinical Investigation. - 0021-9738. ; Jun 2, s. 2620-2628
-
Tidskriftsartikel (refereegranskat)abstract
- Identifying the genetic variants that regulate fasting glucose concentrations may further our understanding of the pathogenesis of diabetes. We therefore investigated the association of fasting glucose levels with SNPs in 2 genome-wide scans including a total of 5,088 nondiabetic individuals from Finland and Sardinia. We found a significant association between the SNP rs563694 and fasting glucose concentrations (P = 3.5 x 10(-7)). This association was further investigated in an additional 18,436 nondiabetic individuals of mixed European descent from 7 different studies. The combined P value for association in these follow-up samples was 6.9 x 10(-26), and combining results from all studies resulted in an overall P value for association of 6.4 x 10(-33). Across these studies, fasting glucose concentrations increased 0.01-0.16 mM with each copy of the major allele, accounting for approximately 1% of the total variation in fasting glucose. The rs563694 SNP is located between the genes glucose-6-phosphatase catalytic subunit 2 (G6PC2) and ATP-binding cassette, subfamily B (MDR/TAP), member 11 (ABCB11). Our results in combination with data reported in the literature suggest that G6PC2, a glucose-6-phosphatase almost exclusively expressed in pancreatic islet cells, may underlie variation in fasting glucose, though it is possible that ABCB11, which is expressed primarily in liver, may also contribute to such variation.
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| 11. |
- Gretarsdottir, Solveig, et al.
(författare)
-
Genome-wide association study identifies a sequence variant within the DAB2IP gene conferring susceptibility to abdominal aortic aneurysm
- 2010
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 42:8, s. 71-692
-
Tidskriftsartikel (refereegranskat)abstract
- We performed a genome-wide association study on 1,292 individuals with abdominal aortic aneurysms (AAAs) and 30,503 controls from Iceland and The Netherlands, with a follow-up of top markers in up to 3,267 individuals with AAAs and 7,451 controls. The A allele of rs7025486 on 9q33 was found to associate with AAA, with an odds ratio (OR) of 1.21 and P = 4.6 x 10(-10). In tests for association with other vascular diseases, we found that rs7025486[A] is associated with early onset myocardial infarction (OR = 1.18, P = 3.1 x 10(-5)), peripheral arterial disease (OR = 1.14, P = 3.9 x 10(-5)) and pulmonary embolism (OR = 1.20, P = 0.00030), but not with intracranial aneurysm or ischemic stroke. No association was observed between rs7025486[A] and common risk factors for arterial and venous diseases-that is, smoking, lipid levels, obesity, type 2 diabetes and hypertension. Rs7025486 is located within DAB2IP, which encodes an inhibitor of cell growth and survival.
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| 12. |
- Zeggini, Eleftheria, et al.
(författare)
-
Meta-analysis of genome-wide association data and large-scale replication identifies additional susceptibility loci for type 2 diabetes
- 2008
-
Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:5, s. 638-645
-
Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association (GWA) studies have identified multiple loci at which common variants modestly but reproducibly influence risk of type 2 diabetes (T2D)(1-11). Established associations to common and rare variants explain only a small proportion of the heritability of T2D. As previously published analyses had limited power to identify variants with modest effects, we carried out meta-analysis of three T2D GWA scans comprising 10,128 individuals of European descent and similar to 2.2 million SNPs (directly genotyped and imputed), followed by replication testing in an independent sample with an effective sample size of up to 53,975. We detected at least six previously unknown loci with robust evidence for association, including the JAZF1 (P=5.0 x 10(-14)), CDC123-CAMK1D (P=1.2 x 10(-10)), TSPAN8-LGR5 (P=1.1 x 10(-9)), THADA (P=1.1 x 10(-9)), ADAMTS9 (P=1.2 x 10(-8)) and NOTCH2 (P=4.1 x 10(-8)) gene regions. Our results illustrate the value of large discovery and follow-up samples for gaining further insights into the inherited basis of T2D.
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| 13. |
- Andersen, Torben, et al.
(författare)
-
A new concept for large deformable mirrors for extremely large telescopes
- 2006
-
Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 6272:1, s. 324-331
-
Konferensbidrag (refereegranskat)abstract
- For extremely large telescopes, there is strong need for thin deformable mirrors in the 3-4 m class. So far, feasibility of such mirrors has not been demonstrated. Extrapolation from existing techniques suggests that the mirrors could be highly expensive. We give a progress report on a study of an approach for construction of large deformable mirrors with a moderate cost. We have developed low-cost actuators and deflection sensors that can absorb mounting tolerances in the millimeter range, and we have tested prototypes in the laboratory. Studies of control laws for mirrors with thousands of sensors and actuators are in good progress and simulations have been carried out. Manufacturing of thin, glass mirror blanks is being studied and first prototypes have been produced by a slumping technique. Development of polishing procedures for thin mirrors is in progress
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| 14. |
- Andersen, Torben, et al.
(författare)
-
A parallel integrated model of the Euro50
- 2004
-
Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5497:1, s. 251-265
-
Konferensbidrag (refereegranskat)abstract
- The Euro50 is an astronomical extremely large telescope for optical and infrared wavelength with a 50 m primary mirror. The telescope will have an elaborate control system ("live optics") to correct for atmospheric and telescope aberrations. To study and predict performance of the complete telescope system, an integrated model combining the structural model of the telescope, optics models, the control systems, and the adaptive optics has been established. Wind is taken into account on the basis of wind tunnel measurements and computer fluid dynamics calculations. Atmospheric aberrations are included using a seven-layer atmosphere model. The integrated model is written in Matlab and is run on a cluster computer to achieve acceptable execution times. Dedicated ordinary differential equation solvers have been written and a special toolkit for communication between Matlab processes on different nodes of the cluster computer has been set up. Preliminary results from the complete integrated model, including adaptive optics, are shown
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| 15. |
- Andersen, Torben, et al.
(författare)
-
An Integrated Model of the European Extremely Large Telescope
- 2008
-
Ingår i: MODELLING, SYSTEMS ENGINEERING, AND PROJECT MANAGEMENT FOR ASTRONOMY III. - : SPIE. - 1996-756X .- 0277-786X. ; 7017, s. 216-227
-
Konferensbidrag (refereegranskat)abstract
- Integrated models including optics, structures, control systems, and disturbances are important design tools for Extremely Large Telescopes (ELTs). An integrated model has keen formulated for the European ELT and it includes telescope structure, main servos, primary mirror segment control system, wind, optics, wavefront sensor, deformable mirror, and an AO reconstructor and controller. There are three model phases: Initialization, execution of a solver to determine time responses, and post-processing. In near future, the model will be applied for performance studies and design trade-offs for the European ELT.
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| 16. |
- Andersen, Torben, et al.
(författare)
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An integrated simulation model of the Euro50
- 2002
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 4757, s. 84-92
-
Konferensbidrag (refereegranskat)abstract
- The Euro50 is a proposed optical telescope with an equivalent aperture of 50 m. It will have a segmented primary mirror and full adaptive optics. To study the interaction of the telescope structure, the control system and the optics, an integrated simulation model has been formulated. The mechanical model is a modal version of an Ansys finite element model. The optics model is based on ray tracing and physical optics. The segments model takes the alignment servos and the segment dynamics into account. Wind variation over the primary mirror is included. Segment control system modeling is in progress. First results clearly demonstrate that a good enclosure is needed to protect the telescope well against wind. The results also suggest that the segment alignment system must have a bandwidth well above the lowest eigenfrequencies of the telescope.
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| 17. |
- Andersen, Torben
(författare)
-
Comparison of optimizers for model predictive thermal control of buildings
- 2024
-
Ingår i: Energy and AI. - 2666-5468. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- Considering recent developments in the energy sector, further reduction of electricity cost and flattening of the electric power demand curve are needed. We have focused on an autonomous electric heater control system that can easily be implemented in existing buildings without strict comfort requirements. Examples are winter heating of warehouses and vacation homes, and heat drying of buildings under construction. We have set up a system that typically reduces electricity cost by about 40% on the basis of automatic weather and real time pricing forecasts. The system uses the building as an energy reservoir over periods with high electricity cost. Using a model predictive control system, we compare use of a genetic algorithm, a particle swarm optimization, and a neural network for heater control, all working in a closed loop to reduce the influence of modeling errors. We have simulated the performance of the systems using realistic data and found that all three optimizers give about the same performance, varying only a few percent in efficiency. However, the computational and memory requirements of the neural network are much lower than for the other optimizers, so it is preferable for use with inexpensive microcontrollers. We carried out a full-scale experiment at a residential house and found agreement with simulation results.
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| 18. |
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| 19. |
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| 20. |
- Andersen, Torben, et al.
(författare)
-
Granskare behöver bättre villkor
- 2011
-
Ingår i: Svenska Dagbladet. - Stockholm : Schibsted Forlag. ; 8/2
-
Tidskriftsartikel (populärvet., debatt m.m.)
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| 21. |
- Andersen, Torben, et al.
(författare)
-
Image-based wavefront sensing for astronomy using neural networks
- 2020
-
Ingår i: Journal of Astronomical Telescopes, Instruments, and Systems. - : SPIE - International Society for Optical Engineering. - 2329-4124. ; 6:3
-
Tidskriftsartikel (refereegranskat)abstract
- Motivated by the potential of non-diffraction limited, real-time computational image sharpening with neu7 ral networks in astronomical telescopes, we have studied wavefront sensing with convolutional neural networks basedon a pair of in-focus and out-of-focus point spread functions. By simulation, we generated a large dataset for trainingand validation of neural networks, and trained several networks to estimate Zernike polynomial approximations forthe incoming wavefront. We included the effect of noise, guide star magnitude, blurring by wide band imagining, andbit depth. We conclude that the “ResNet” works well for our purpose, with a wavefront RMS error of 130 nm forr0 = 0.3 m, guide star magnitudes 4–8, and inference time of 8 ms. It can also be applied for closed-loop operation inan adaptive optics system. We also studied the possible use of a Kalman filter or a recurrent neural network and foundthat they were not beneficial to performance of our wavefront sensor
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| 22. |
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| 23. |
- Andersen, Torben J, et al.
(författare)
-
Multinational Corporate Strategy-making : Integrating International Business and Strategic Management
- 2017. - 1
-
Ingår i: <em>The Responsive Global Organization: New Insightsfrom Global Strategy and International Business</em>. - : Emerald Group Publishing Limited. - 9781787148321 - 9781787148314 ; , s. 13-33
-
Bokkapitel (refereegranskat)abstract
- This chapter contends that the international business (IB) and strategic management (SM) fields have many commonalities that should be considered in a turbulent globalized business context. IB studies refer to the need for local integration and local adaptation whereas empirics in SM pinpoint the complementary effects of central planning and decentralized decisionmaking. We present and synthesize these rather field specific perspectives and try to synthesize insights from both fields in an adaptive strategy-making model including the effects of autonomous subsidiary initiatives and intended mandates from corporate headquarters. The model considers local subsidiary actions of both operational and strategic nature and we argue that it may be futile to distinguish between these effects as incremental operational responses can cumulate into more substantial changes over time with dimensions of strategic adaptation. The model provides a foundation for further considerations about how to combine central intent and direction with decentralization and autonomous initiatives in the multinational corporation.
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| 24. |
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| 25. |
- Andersen, Torben, et al.
(författare)
-
Linearized Model of an Actively Controlled Cable for a Carlina Diluted Telescope
- 2013
-
Ingår i: Improving the performances of current optical interferometers & future designs : Proceedings of Haute Provence Observatory Colloquium (23-27 September 2013) - Proceedings of Haute Provence Observatory Colloquium (23-27 September 2013).
-
Konferensbidrag (refereegranskat)
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| 26. |
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| 27. |
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| 28. |
- Andersen, Torben, et al.
(författare)
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Modeling of structural cables
- 2018
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Ingår i: Modeling, Systems Engineering, and Project Management for Astronomy VIII. - : SPIE. - 9781510619630 ; 10705
-
Konferensbidrag (refereegranskat)abstract
- For many applications, including future giant telescopes, there is increased interest in structural cables. Usually integrated models, i.e. combined models of structures, optics and control systems are used for modeling of telescopes. Performance of structural cables is non-linear, so often a linearization is needed to include cable models in integrated models of telescopes. We present two different linear models describing static and dynamic performance of a cable near an equilibrium operating point. The models are lug-in» models that in a black box form give end point forces as outputs, with end point movements as inputs. Using an example, we compare the two models and we outline the benefits of each of the models. Although we here focus on modeling of telescopes, the techniques are useful also for other applications.
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| 29. |
- Andersen, Torben, et al.
(författare)
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Neural networks for image-based wavefront sensing for astronomy
- 2019
-
Ingår i: Optics Letters. - : Optical Society of America. - 0146-9592 .- 1539-4794. ; 44:18, s. 4618-4621
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Tidskriftsartikel (refereegranskat)abstract
- We study the possibility of using convolutional neural networks for wavefront sensing from a guide star image in astronomical telescopes. We generated a large number of artificial atmospheric wavefront screens and determined associated best-fit Zernike polynomials. We also generated in-focus and out-of-focus point-spread functions. We trained the well-known “Inception” network using the artificial data sets and found that although the accuracy does not permit diffraction-limited correction, the potential improvement in the residual phase error is promising for a telescope in the 2–4 m class.
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| 30. |
- Andersen, Torben, et al.
(författare)
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Nordic HRM: Distinctiveness and Resilience
- 2016
-
Ingår i: International Human Resource Management: Contemporary HR Issues in Europe. Eds.: Dickmann, M., Brewster, C. and Sparrow, P.. - London : Routledge. - 9781138776036 ; , s. 100-114
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Bokkapitel (refereegranskat)
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| 31. |
- Andersen, Torben, et al.
(författare)
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Novel concept for large deformable mirrors
- 2006
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Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286. ; 45:7
-
Tidskriftsartikel (refereegranskat)abstract
- Large, high-bandwidth deformable mirrors (DMs) with thousands of actuators for adaptive optics are of high interest for existing large telescopes and indispensable for construction of efficient future extremely large telescopes. Different actuation and sensing principles are possible. We propose a novel concept using commercially available voice coil actuators attached to the back of the mirror with suction cups and using LVDT sensors on the actuators for local stabilization. Also, a new low-cost sensor for easy measurement of DM displacement or velocity has been developed. It has a sensitivity better than 20 nm and a bandwidth wider than 20 to 1000 Hz. Finally, studies are in progress of global, hierarchical mirror form controllers based on many parallel multiple-input, multiple-output regulators of low order.
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| 32. |
- Andersen, Torben, et al.
(författare)
-
Reputation and Rational Expectations
- 1987
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The paper considers the importance of reputation in relation to disinflationary policies in a continuous time ration expectations model, where the private sector has incomplete information about the true preferences of the government. It is proved that there is a unique equilibrium with the important property that the costs of disinflation arise in the start of the game where the policy has not yet gained credibility.
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| 33. |
- Andersen, Torben, et al.
(författare)
-
Status of the Euro50 project
- 2004
-
Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 5489:1, s. 407-416
-
Konferensbidrag (refereegranskat)abstract
- The Euro50 is an extremely large telescope for optical and infrared wavelength with a 50 m primary mirror. It has a segmented, aspherical primary mirror and an aspherical, deformable secondary in a Gregorian layout. A tentative conceptual design exists and has been documented in a study report. Recent activities have concentrated on the science case for extremely large telescopes in the 50 m class and on identification of potential technical "show stoppers". The science case investigation has identified four fields of particular interest. The studies of critical technical issues have concentrated on atmospheric dispersion effects for high-resolution adaptive optics for extremely large telescopes, and on the influence of wind and other disturbances on wavefront control. Wind load on the telescope, the primary mirror and the enclosure has been studied using wind tunnel measurements and computational fluid dynamics. The impact of wind on the total system has been investigated using an integrated model that includes the telescope structure, the primary mirror segment alignment system, the secondary mirror alignment system, and single conjugate adaptive optics using the deformable secondary mirror. The first, tentative results show that wind disturbances may be significant and that the task of correcting for wind residuals may be at least as large for the adaptive optics system as that of correcting for atmospheric aberrations. The results suggest that use of extremely large telescopes for observations of earth-like planets around nearby stars may imply a considerable challenge
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| 34. |
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| 35. |
- Andersen, Torben, et al.
(författare)
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Svensk Finanspolitik
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 36. |
- Andersen, Torben, et al.
(författare)
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Swedish Fiscal Policy
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 37. |
- Andersen, Torben, et al.
(författare)
-
Technology demonstration solar telescope
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The conceptual design of the Large Earth-based Solar Telescope (LEST)has evolved through the years. In 1995-97 it was discussed whether atechnology demonstration telescope could be built at a lower cost thanthe LEST originally proposed. In 1997, a de-scoped LEST design, theso-called "Mini-LEST", was conceived and proposed to the LEST community.The telescope has an innovative design with a small field lens thatmakes the way for simple adaptive optics. The optical performance isexcellent. It has a low-cost alt-az steel structure with a large slewingring for the azimuth movement and direct-drive motors for simplicity.The telescope is open but can easily be modified to a Helium telescopeto compare performance of Helium filled telescopes vs. open telescopes.The tower has also been simplified to reduce cost. It has a dome designthat provides protection for wind and yet permits open-air observations.The budget shows an overall cost of 37.6 MSEK and an exectution time ofless than four years.
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| 38. |
- Andersen, Torben, et al.
(författare)
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The Euro50 Extremely Large Telescope
- 2003
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Ingår i: Future Giant Telescopes. Proceedings of the SPIE.. - 081944619X ; 4840, s. 214-225
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Konferensbidrag (refereegranskat)abstract
- Euro50 is a proposed optical telescope with an equivalent primary mirrordiameter of 50 m. Partners of the collaboration are institutes inSweden, Spain, Ireland, Finland, and the UK. The telescope will have asegmented primary mirror and an aplanatic Gregorian configuration withtwo elliptical mirrors. For a 50 m telescope there would be noeconomical advantage in going to a spherical primary. The size of theprimary mirror segments (2 m) has been selected on the basis of aminimization of cost. An adaptive optics system will be integrated intothe telescope. The telescope will have three operational modes: Seeinglimited observations, single conjugate adaptive observations in theK-band, and dual conjugate observations also in the K-band. An upgradeto adaptive optics also in the visible down to 500 nm is foreseen. Therewill be an enclosure to protect the telescope against adverse weatherand wind disturbances. Integrated simulation models are underdevelopment. The project time will be 10 years and the cost some 591MEuros.
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| 39. |
- Andersen, Torben, et al.
(författare)
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The Role of Credibility for the Effects of a Change in the Exchange-Rate Policy
- 1987
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This paper analyses the real and monetary effects of a shift in the exchange-rate policy in an economy where the private sector is uncertain about the true intentions of the government. In a repeated game of incomplete information, we show that a shift towards a tight, fixed exchange-rate policy leads to a loss in output and to a deficit on the current account in the period in which the policy lacks credibility. We also show that the long interest rate is above the short interest rate, reflecting the risk that the government reneges on its announced exchange-rate target.
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| 40. |
- Andersen, Torben, et al.
(författare)
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The Swedish 50 m ELT
- 2002
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Ingår i: Beyond conventional adaptive optics; ESO Conference and Workshop Proceedings. - 3923524617 ; 58, s. 7-10
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Konferensbidrag (refereegranskat)
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| 41. |
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| 42. |
- Ardeberg, Arne, et al.
(författare)
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A European ELT design study
- 2005
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Ingår i: Proceedings of the Inaternational Astronomical Union, IAU Symposium. ; 232, s. 432-442
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Konferensbidrag (refereegranskat)
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| 43. |
- Ardeberg, Arne, et al.
(författare)
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Clusters as probes of distance, evolution, and chemistry of galaxies
- 2003
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 5382:1, s. 47-56
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Konferensbidrag (refereegranskat)abstract
- Stellar clusters are highly useful as tools for determination of distances, ages and abundances of heavy elements of galaxies, also at larger distances. Their utility for these purposes has, so far, been severely limited, mainly due to image crowding. The introduction of Extremely Large Telescopes (ELTs) with full adaptive optics (AO) and near diffraction limited performance should imply a drastic improvement concerning the usefulness of clusters and the limiting distances of high quality data. We have made a study of stellar clusters as probes of distance, evolution and chemistry of galaxies at distances from one to twenty Mpc. From data on the Stromgren uvby system, partly from direct measurements taken from the literature, we have synthesized test clusters, one open and one globular, as well as galactic backgrounds. The clusters have been embedded in the backgrounds and located at distances between one and twenty Mpc. Here, vby data have been measured, reduced and analyzed. Color-magnitude diagrams (CMDs), metallicity diagrams (MDs) and luminosity functions (LFs) have been constructed. They have been evaluated absolutely and compared to the corresponding template data. We conclude that with a 50 m AO ELT, for open as well as globular clusters, MDs are of high quality for clusters out to and beyond 5 Mpc and useful out to 10 Mpc. CMDs are of very high quality well beyond 5 Mpc. They are of high scientific value out to and beyond 10 Mpc and valuable for clusters even out to 20 Mpc. LFs are highly informative well beyond 10 Mpc and still rather valuable at 20 Mpc. With sufficient measurement data available, LFs are useful for clusters in galaxies even beyond 20 Mpc
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| 44. |
- Ardeberg, Arne, et al.
(författare)
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ELTs, adaptive optics, and wavelengths
- 2008
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. ; 6986, s. 1-698608
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Konferensbidrag (refereegranskat)
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| 45. |
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| 46. |
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| 47. |
- Ardeberg, Arne, et al.
(författare)
-
Euro50: Proposal for a 50 m Optical and Infrared Telescope
- 2001
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Ingår i: Reviews in modern astronomy. 15, Astronomy with large telescopes from ground and space. ; 18
-
Konferensbidrag (refereegranskat)abstract
- Staff from Instituto de Astrofisica de Canarias, Lund Observatory,Physics Department and Larmor Research Institute at Galway, and TuorlaObservatory is collaborating on studies for a 50 m optical and infraredtelescope. The telescope concepts are based on the work on extremelylarge telescopes carried out during 1991-2000 at Lund Observatory, andon the experience from the 10.4 m segmented Grantecan telescopepresently under construction. The proposed 50 m telescope is a fullyadaptive Nasmyth telescope with a Ritchey Chretien configuration. Itwill have an aspherical, segmented primary mirror with 2 m largesegments and a deformable secondary. Adaptive optics will be implementedin several steps. From the beginning, there will be single-conjugateadaptive optics for the K-band. Next, and within the first year ofoperation, the telescope will have single-conjugate adaptive optics forvisible wavelengths. As a third step, and another year of operation,dual-conjugate adaptive optics will be made available for the K-band.The telescope will be housed in a co-rotating enclosure at the Roque delos Muchachos observatory on La Palma. Further studies are in progressaiming at preparation of a proposal during the first half of 2002.
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| 48. |
- Ardeberg, Arne, et al.
(författare)
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From Euro50 towards a European ELT
- 2006
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 6267 II, s. 26725-26725
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Konferensbidrag (refereegranskat)abstract
- With Euro50 as a convenient telescope laboratory, the Euro50 team has continued development aiming at a European extremely large telescope (ELT). Here, we give a progress report. The needs of science and instrumentation are briefly discussed as is the importance of photometric stability and precision. Results are reported from work on integrated modelling. Details are given concerning point-spread functions (PSFs) obtained with and without adaptive optics (AO). Our results are rather encouraging concerning AO photometry and compensation of edge sensor noise as well as regarding seeing-limited ELT operation. The current status of our development of large deformable mirrors is shown. Low-cost actuators and deflection sensors have been developed as have hierarchic control algorithms. Fabrication of large thin mirror blanks as well as polishing and handling of thin mirrors has been studied experimentally. Regarding adaptive optics, we discuss differential refraction and the limitations imposed by dispersive optical path differences (OPDs) and dispersive anisoplanatism. We report on progress in laser guide star (LGS) performance and a real-time online experiment in multi-conjugate AO (MCAO). We discuss ELTs, high-resolution spectroscopy and pupil slicing with and without use of AO. Finally, we present some recent studies of ELT enclosure options.
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| 49. |
- Ardeberg, Arne, et al.
(författare)
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Science drivers of a 50-m AO telescope
- 2003
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Ingår i: Proceedings of the SPIE - The International Society for Optical Engineering. - : SPIE. - 1996-756X .- 0277-786X. ; 5382:1, s. 37-46
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Konferensbidrag (refereegranskat)abstract
- Some leading science programs undertaken with Very Large Telescopes and challenges driving the progress of the Extremely Large Telescopes are discussed together with the corresponding requirements. They concern expolanets, Earth-like planets, habitable zones, formation of stars and galaxies, first stars and cosmology. A description is attempted
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| 50. |
- Arlien-Soborg, Mai C., et al.
(författare)
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Acromegaly management in the Nordic countries: A Delphi consensus survey
- 2024
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Ingår i: CLINICAL ENDOCRINOLOGY. - : WILEY. - 0300-0664 .- 1365-2265.
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveAcromegaly is associated with increased morbidity and mortality if left untreated. The therapeutic options include surgery, medical treatment, and radiotherapy. Several guidelines and recommendations on treatment algorithms and follow-up exist. However, not all recommendations are strictly evidence-based. To evaluate consensus on the treatment and follow-up of patients with acromegaly in the Nordic countries.MethodsA Delphi process was used to map the landscape of acromegaly management in Denmark, Sweden, Norway, Finland, and Iceland. An expert panel developed 37 statements on the treatment and follow-up of patients with acromegaly. Dedicated endocrinologists (n = 47) from the Nordic countries were invited to rate their extent of agreement with the statements, using a Likert-type scale (1-7). Consensus was defined as >= 80% of panelists rating their agreement as >= 5 or <= 3 on the Likert-type scale.ResultsConsensus was reached in 41% (15/37) of the statements. Panelists agreed that pituitary surgery remains first line treatment. There was general agreement to recommend first-generation somatostatin analog (SSA) treatment after failed surgery and to consider repeat surgery. In addition, there was agreement to recommend combination therapy with first-generation SSA and pegvisomant as second- or third-line treatment. In more than 50% of the statements, consensus was not achieved. Considerable disagreement existed regarding pegvisomant monotherapy, and treatment with pasireotide and dopamine agonists.ConclusionThis consensus exploration study on the management of patients with acromegaly in the Nordic countries revealed a relatively large degree of disagreement among experts, which mirrors the complexity of the disease and the shortage of evidence-based data.
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