| 1. |
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| 2. |
- Almbladh, Carl-Olof, et al.
(författare)
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THEORY OF RESONANT EMISSION PROCESSES IN METALS
- 1984
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Ingår i: Annals of the Israel Physical Society. - 0309-8710. ; 6, s. 309-311
-
Konferensbidrag (refereegranskat)abstract
- A simple and transparent formalism is presented to treat emission processes in general and resonant emission processes in metals in particular. As an example resonant photoemission in Cu metal is discussed.
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| 3. |
- Aryasetiawan, F., et al.
(författare)
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Multiple Plasmon Satellites in Na and Al Spectral Functions from Ab Initio Cumulant Expansion
- 1996
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 77:11, s. 2268-2271
-
Tidskriftsartikel (refereegranskat)abstract
- The valence photoemission spectra of alkali metals exhibit multiple plasmon satellite structure. The calculated spectral functions within the GW approximation show only one plasmon satellite at too large binding energy. In this Letter we use the cumulant expansion approach to obtain the spectral functions of Na and Al from ab initio calculations including the effects of band structure. The GW spectral functions are dramatically improved and the positions of the multiple plasmon satellites are in very good agreement with experiment while their intensities cannot be explained from intrinsic effects only.
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| 4. |
- Bardyszewski, Witold, et al.
(författare)
-
A New Approach to the Theory of Photoemission from Solids
- 1985
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 32, s. 439-439
-
Tidskriftsartikel (refereegranskat)abstract
- By neglecting certain terms in the Hamiltonian (of importance only in the immediate neighbourhood of the threshold energy) we are able to write an exact expression for the photoemission intensity which involves the standard time inverted LEED state and broadened hole-states. If inelastic extrinsic losses are neglected our expression is similar to the one used by e.g. Feibelman and Eastman [1], Pendry [2] and Spanjaard et al. [3]. Our theory also allows inelastic losses (including interference between intrinsic and extrinsic losses) to be evaluated. The expressions are similar to those obtained by Inglesfield [4], but the damping effect no longer has to be put in by hand. Our theory further can handle not only core electron but also valence electron photoemission and it is not restricted to metals but applies to all types of solids. We have also traced why and when Inglesfield's one step theory agrees with a semiclassical calculation.
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| 5. |
- Bardyszewski, Witold, et al.
(författare)
-
EFFECTS OF MANY-BODY INTERACTIONS IN EXTENDED X-RAY ABSORPTION FINE STRUCTURE SPECTROSCOPY (EXAFS)
- 1987
-
Ingår i: Journal de Physique Colloques. - : EDP Sciences. - 0449-1947. ; 48 (C9), s. 1101-1104
-
Konferensbidrag (refereegranskat)abstract
- Abstract : We present the first a priori derivation of a many-body theory for EXAFS with clearly defined approximations and with final expressions which are feasible for quantitative evaluations. We conclude that the conventional EXAFS expression should be complemented with a term that crudely is the main term, energy-shifted and scaled down by a factor of order 0.2-0.3. Further the f-factors depend significantly, not only on the scattering properties of the individual ions, but also on the electron energy-loss properties of the material itself.
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| 6. |
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| 7. |
- Bendix, Lars, et al.
(författare)
-
Teaching software development using extreme programming
- 2008
-
Ingår i: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540779339 - 9783540779346 ; 4821, s. 166-189
-
Tidskriftsartikel (refereegranskat)abstract
- Software development is a complex area and extensive practice and reflection is required in order to obtain a good understanding of the different tasks involved in going from idea to deliverable software. To help in providing this understanding, we have developed a team programming course based on extreme programming and a coaching course. We discuss how these courses affect the curriculum, the design of the courses, and our experience from running them for four years, involving over 100 students per year. We also discuss how we have used the extreme programming approach to support the learning cycle through the use of iterative learning, peer learning and a fixed-time budge
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| 8. |
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| 9. |
- Campbell, L, et al.
(författare)
-
Interference between extrinsic and intrinsic losses in x-ray absorption fine structure
- 2002
-
Ingår i: Physical Review B. - 1550-235X. ; 65:6, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- The interference between extrinsic and intrinsic losses in x-ray absorption fine structure (XAFS) is treated within a Green's-function formalism, without explicit reference to final states. The approach makes use of a quasiboson representation of excitations and perturbation theory in the interaction potential between electrons and quasibosons. These losses lead to an asymmetric broadening of the main quasiparticle peak plus an energy-dependent satellite in the spectral function. The x-ray absorption spectra (XAS) is then given by a convolution of an effective spectral function over a one-electron cross section. It is shown that extrinsic and intrinsic losses tend to cancel near excitation thresholds, and correspondingly, the strength in the main peak increases. At high energies, the theory crosses over to the sudden approximation. These results thus explain the observed weakness of multielectron excitations in XAS. The approach is applied to estimate the many-body corrections to XAFS, beyond the usual mean-free path, using a phasor summation over the spectral function. The asymmetry of the spectral function gives rise to an additional many-body phase shift in the XAFS formula.
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| 10. |
- Danhäll, D, et al.
(författare)
-
Naturligt grupperat arbete vid Volvo Lastvagnar – Delrapport 1
- 1989
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report for the company in question (the Volvo Truck Company) which is financed by the company and partly also by a research foundation. It is a matter of a work that in this particular case were carried out during nine years in a number of experimental workshops located outside the Chalmers University of Technology. These workshops were financed by the Volvo Automobile and Truck companies. This achievement, as the final contribution to the Swedish automotive industry after having already treated this research field/problem area for more than two decades before this particular period if time (involving several junior and senior research competencies, as well as industrial and governmental foundings). Specifically, this publication explains how the authors dealt with the product architecture and product variation of the automotive products disassembled, which proved to necessary to be carried out in one of the experimental workshops (several complete automobiles and one heavy truck chassis were disassembled combined with having product data accessible in form of paper print-outs as well as by appropriate computer connections to the two Volvo companies etc.). That is, by using a special sort of “design analysis by means of axonometric hand-drawn illustrations” (see a conference contribution from 1992 that also is registered and available as o PDF-document at Chalmers Public Library (CPL) (a self-developed method found out together with a junior research competency from the School of Architecture at Chalmers).
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| 11. |
- Danhäll, D, et al.
(författare)
-
Naturligt grupperat arbete vid Volvo Lastvagnar – Delrapport 2
- 1989
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report for the company in question (the Volvo Truck Company) which is financed by the company and partly also by a research foundation. It is a matter of a work that in this particular case were carried out during nine years in a number of experimental workshops located outside the Chalmers University of Technology. These workshops were financed by the Volvo Automobile and Truck companies. This achievement, as the final contribution to the Swedish automotive industry after having already treated this research field/problem area for more than two decades before this particular period if time (involving several junior and senior research competencies, as well as industrial and governmental foundings). Specifically (and as stated for the previous report), this publication explains how the authors dealt with the product architecture and product variation of the automotive products disassembled, which proved to necessary to be carried out in one of the experimental workshops (several complete automobiles and one heavy truck chassis were disassembled combined with having product data accessible in form of paper print-outs as well as by appropriate computer connections to the two Volvo companies etc.). That is, by using a special sort of “design analysis by means of axonometric hand-drawn illustrations” (see a conference contribution from 1992 that also is registered and available as o PDF-document at Chalmers Public Library (CPL) (a self-developed method found out together with a junior research competency from the School of Architecture at Chalmers).
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| 12. |
- Danhäll, D, et al.
(författare)
-
Naturligt grupperat arbete vid Volvo Lastvagnar – Slutrapport
- 1990
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report for the company in question (the Volvo Truck Company) which is financed by the company and partly also by a research foundation. It is a matter of a work that in this particular case were carried out during nine years in a number of experimental workshops located outside the Chalmers University of Technology. These workshops were financed by the Volvo Automobile and Truck companies. This achievement, as the final contribution to the Swedish automotive industry after having already treated this research field/problem area for more than two decades before this particular period if time (involving several junior and senior research competencies, as well as industrial and governmental foundings). A comment: As was the praxis during this (early) period of time at Chalmers University of Technology, as well as probably at some other universities. This means that frequent and vast academic publication by means of e.g. conference papers and refereed contributions to scientific journals was almost unheard of. At least so for some of the applied science disciplines. However, today are the situation indeed very different (i.e. earlier was the publication in many respects focused on trying to satisfy the executive administrator the research foundation in question etc.). To be more precise, this early praxis was definitively the case for the research and development work carried out at the Department of Transportation (a broadly applied science discipline), which was characterized by more practical strives to e.g. engineer research results. Rather than relying on truer scientific efforts in a narrower sense. Functional satisfaction (i.e. something engineered work as planned instead verification/falsification of a hypothesis) was judged as being a primary aim of this research and development work. Therefore are (in the context of the publications registered in Chalmers Public Library CPL) the author making distinctions between consumer reports, on one hand. And, one the other hand, reports and preprints (manuscripts), while instead the academically orientated publications are various sort of scientific contributions presented at conferences or published in scientific journals (actually it is somewhat more complex, but further explanations are omitted here). The consumer reports were aimed at a various external organization with who the authors cooperated, and these are in many cases not available in PDF format to be easily read by logging in at CPL. This particular approach has judged as being fair/relevant fair in order to mirror of work conducted by the author or authors during the passing decades. Besides, the competencies at Chalmers Library, who actually have been very helpful, have not managed to provide appropriate answers to the various questions implied being at hand just above (this despite trying to get hold of such answers, hence this very comment).
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| 13. |
- Engström, Tomas, 1950, et al.
(författare)
-
Design Analysis by Means of Axonometric Hand–drawn Illustrations
- 1992
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This scientific contribution summarizes some of the research and development work carried out by the authors while we were engaged in the Volvo Automobile Company’s assembly plant in Uddevalla. It explains how we managed the illustrate the product architecture and product variation of the automobile model in question (the Volvo 700 model). Comment: Our clients (the project organisation at Volvo) allowed us to make scientific contributions reporting on e.g. principles and practises during the life of this assembly plant, but they were not keen letting us publish any hard information (many other scientists were far interested publishing just anything). For strategic reasons would, in fact, the principles be kept secret instead (however these principles, though practised by Volvo, were actually never officially/publically absorbed by the Volvo companies) (nowadays are all of the knowledgeable individuals etíher dead or retired). Most probably do similar efforts calling for an experimental workshop in connection with an industrial change, as well as access to similar competencies (various knowledgeable practitioners, as well as senior and junior research competencies, were inventible called for) (just to master the specific nomenclature at hand within the various Volvo companies was really difficult for us) (who will help an external scientist if this requires extra work just to understand what he or she wants?). This is a situation that is almost an impossibility today, with the ways research and development work are organised and financed today at Chalmers University of Technology (in fact, it was far more anarchistic earlier, as long as you were able to finance the efforts in question).
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| 14. |
- Engström, Tomas, 1950, et al.
(författare)
-
Naturligt grupperat arbete vid Volvo Lastvagnar – Förstudie
- 1989
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report for the company in question (the Volvo Truck Company) which is financed by the company and partly also by a research foundation. It is a matter of a work that in this particular case were carried out during nine years in a number of experimental workshops located outside the Chalmers University of Technology. These workshops were financed by the Volvo Automobile and Truck companies. This achievement, as the final contribution to the Swedish automotive industry after having already treated this research field/problem area for more than two decades before this particular period if time (involving several junior and senior research competencies, as well as industrial and governmental foundings). More specifically, this publication shows how the initiation of e long cooperation project with the Volvo Truck Company as started. It illustrated how an engine preheater for a heavy truck chassis is assembled on one of the two assembly lines in the Volvo Tuve plant in Gothenburg. It became obvious for others and us that the original logic of this engine preheater was lost as the components required alternately were fitted at different work stations (implying the fact that the logic of the product architecture and product variation of the physical product are totally destroyed) (in fact, the situation was even worse while taking the computer formalized product information on both of the two Volvo companies into consideration.
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| 15. |
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| 16. |
- Fischer, Kerstin, et al.
(författare)
-
Five-year results from a randomized, controlled trial on early and delayed loading of implants supporting full-arch prosthesis in the edentulous maxilla.
- 2008
-
Ingår i: Clin Oral Implants Res. - 1600-0501. ; 19:5, s. 433-41
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: The overall aim was to compare the clinical outcomes of early and delayed implant loading in the totally edentulous maxilla during 5 years of function. MATERIALS AND METHODS: Twenty-four patients with edentulous maxillae were randomized in two groups and subjected to early (test, n=16) or delayed (control, n=8) loading. A total of 142 implants were placed and 139 implants (Straumann AG) were loaded with full-arch bridges and followed for 5 years. RESULTS: All patients received and maintained a fixed bridge throughout the study period. Five (5.3%) test implants in three patients and two (4.3%) control implants in two patients were lost during the 5 years (NS). There were no differences in implant stability as measured with resonance frequency analysis at 5 years. More bone loss occurred at test than at control implants, -0.8 mm (SD 1.2) vs. -0.3 mm (SD 1.1), respectively. However, test implants showed a more coronal marginal bone level than control implants after 5 years, 2.9 mm (SD 1.1) vs. 3.7 mm (SD 1.2) from the implant shoulder, respectively. No control implants and four (4.4%) test implants in three (18.8%) patients showed >3 mm bone loss after 5 years. Two of the latter implants in one patient also showed increased probing depths, bleeding at probing and plaque accumulation. Tooth fracture was the most common prosthetic complication. The use of lingual gold onlay effectively reduced the number of resin-related complications as opposed to a resilient mouth guard. CONCLUSIONS: The present randomized controlled trial showed no important differences between early and delayed loading of implants in the edentulous maxilla after 5 years of function. A favourable long-term marginal bone response to the sandblasted large-grit acid-etched (SLA) surface was observed. Technical complications were mainly resin-related which could be avoided by the use of a lingual gold onlay. It is concluded that early loading of SLA-surface implants for support of full-arch bridges represents a viable therapy for the totally edentulous maxilla.
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| 17. |
- Fleck, Marcus, et al.
(författare)
-
Dynamical Mean-Field Theory for Doped Antiferromagnets
- 1998
-
Ingår i: Physical Review Letters. - 1079-7114. ; 80, s. 2393-2393
-
Tidskriftsartikel (refereegranskat)abstract
- We have generalized the dynamical mean-field theory to study the doping dependence of the crossover from antiferromagnetic to short-range order modeled by an incommensurate spin density wave in the Hubbard model. The local self-energy which includes spin fluctuations gives quasiparticle weights and spectral properties in good agreement with quantum Monte Carlo and exact diagonalization data in two dimensions. The spectra at finite doping are characterized by a Mott-Hubbard “gap” accompanied by a pseudogap induced by the local spin order.
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| 18. |
- Fleck, Marcus, et al.
(författare)
-
Magnetic phases near the Van Hove singularity in s- and d-band Hubbard models
- 1997
-
Ingår i: Physical Review B. - 1550-235X. ; 56:6, s. 3159-3159
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the magnetic instabilities of the nondegenerate (s-band) and a degenerate (d-band) Hubbard model in two dimensions using many-body effects due to particle-particle diagrams and Hund’s rule local correlations. The density of states and the position of the Van Hove singularity change depending on the value of next-nearest-neighbor hopping t′. The Stoner parameter is strongly reduced in the s-band case, and ferromagnetism survives only if the electron density is small and the band has flat regions. Due to next-nearest-neighbor hopping there are flat regions in Γ−X and Γ−Y directions. In contrast, for the d-band case the reduction of the Stoner parameter which follows from particle-particle correlations is much smaller and ferromagnetism survives to a large extent. Inclusion of local spin-spin correlations has a limited destabilizing effect on the magnetic states.
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| 19. |
- Fleck, M., et al.
(författare)
-
Magnetism near the Van Hove singularity
- 1998
-
Ingår i: Journal of Magnetism and Magnetic Materials. - 0304-8853. ; 177-181, s. 599-601
-
Tidskriftsartikel (refereegranskat)abstract
- We study the phase diagrams of the s-band and d-band Hubbard model in two dimensions including electron correlations. While the ferromagnetic instability in the s-band case occurs only near the Van Hove singularity, ferromagnetism is more stable in the d-band model, and the values of the Stoner parameters in transition metals are reduced below their LDA values.(14 refs)
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| 20. |
- Fleck, Marcus, et al.
(författare)
-
Optical properties of doped antiferromagnets
- 1999
-
Ingår i: Journal of Superconductivity. - 0896-1107. ; 12:1, s. 147-149
-
Tidskriftsartikel (refereegranskat)abstract
- We investigate the consequences of an incommensurate magnetic order in doped La2-xSrxCuO4 using dynamical mean-field theory for the effective single-band model. The high-energy optical transitions are due to high-energy excitations across large Mott-Hubbard 'gap,' while low-energy excitations involve a pseudogap induced by the local spin order. The latter lead to a strong drop in the scattering rate at low ω, in qualitative agreement with the experimental data.(16 refs)
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| 21. |
- Fleck, M., et al.
(författare)
-
Quasiparticle broadening in insulating copper oxides
- 1999
-
Ingår i: Physica B. ; 259-261, s. 729-731
-
Tidskriftsartikel (refereegranskat)abstract
- We calculate the spectral function of the half-filled two-dimensional Hubbard model with realistic hopping integrals for Sr2CuO2Cl2 within the dynamical mean-field theory at finite temperatures. It is shown that precursor effects of incommensurate spin dynamics lead to an incoherent broadening of the quasiparticle peaks on an energy scale that depends on local spin order. This might serve as an indirect method of detecting changes of local spin order under doping.
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| 22. |
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| 23. |
- Fujikawa, Takashi, et al.
(författare)
-
A self-consistent optical potential theory for atoms in solids
- 1998
-
Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 88-91, s. 649-655
-
Tidskriftsartikel (refereegranskat)abstract
- We develop an approximation for the optical potential in a solid, valid at intermediate energies, i.e. energies greater than 50 eV. The present approximation for the optical potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron, and can then achieve a corresponding separation of the optical potential. We apply this method to electron-Ne and -Ar elastic scatterings and find a satisfactory agreement with the observed results. We also study the importance of self-consistency and the sensitivity to a parameter, the average excitation energy.
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| 24. |
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| 25. |
- Hallman, Mats, et al.
(författare)
-
A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone.
- 2002
-
Ingår i: Journal of oral and maxillofacial surgery (Print). - : Elsevier BV. - 0278-2391 .- 1531-5053. ; 60:3, s. 277-284; discussion 285
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The purposes of this study were 1) to evaluate the survival rate of implants placed in maxillary sinuses augmented with bovine hydroxyapatite and autogenous bone 6 months before implant surgery and 2) to estimate dimensional changes of the bone graft with time using a new radiographic method. PATIENTS AND METHODS: Thirty maxillary sinuses in 20 consecutive patients with severe resorption (mean, 3.8 mm of remaining alveolar bone) were augmented with a mixture of 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue to enable the placement of screw-shaped dental implants. After 6 months of primary healing, 108 implants were placed and followed with clinical and radiographic examinations during the first year of loading. Measurements of changes in height, width, and length of the grafted material were made on tomographic Scanora (Soredex Orion Corporation Ltd, Helsinki, Finland) and panoramic radiographs taken 3 and 12 months after grafting and after 1 year of bridge loading. RESULTS: Ten implants in 6 patients were lost during the study (9 before loading and 1 after 1 year of functional loading), for a survival rate of 90.7%. All patients received fixed restorations, and the bridge survival rate was 100% after 1 year of loading. Small (<10%) but statistically significant dimensional changes in the grafted material were seen during the study period. CONCLUSIONS: Acceptable short-term results can be obtained with implants placed after the use of bovine hydroxyapatite and autogenous bone for maxillary sinus floor augmentation. These grafts show good resistance to resorption.
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| 26. |
- Hatakada, K, et al.
(författare)
-
Theoretical study of the non-local optical potential in EXAFS spectra
- 2001
-
Ingår i: Journal of Synchrotron Radiation. - 1600-5775. ; 8:2, s. 207-209
-
Tidskriftsartikel (refereegranskat)abstract
- We study the optical potential effects on the extended x-ray absorption fine structure (EXAFS) and x-ray photoelectron diffraction (XPD) spectra. For the valence electron optical potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local optical potential for the core electron part based on GW-approximation. In the Br K-edge EXAFS spectra the present optical potential gives rise to the phase difference and the amplitude reduction; the agreement with the experimental result is excellent. In the N-1s XPD spectra for N2/Ni(100), the spherical wave effects enhance the effects due to the optical potential.(19 refs)
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| 27. |
- Hatakada, K., et al.
(författare)
-
Theory of spin-polarized optical potential
- 2001
-
Ingår i: Journal of Synchrotron Radiation. - 1600-5775. ; , s. 210-212
-
Tidskriftsartikel (refereegranskat)abstract
- We develop an approximation for the non-local spin-polarized optical potential theory for atoms in solids at intermediate and high energy. The present approximation for the optical potential builds on the GW-expression. We separate the RPA polarization propagator into a core electron and a valence electron part, and can then achieve a corresponding separation of the optical potential. For the valence electron optical potential we use a local density approximation because the charge density changes fairly slowly, whereas we use a non-local optical potential for the core electron part. Both of them depend on the spin-polarization. We apply this method to electron-Fe elastic scattering in solids, and discuss the results.(16 refs)
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| 28. |
- Hedin, Görel, et al.
(författare)
-
Coaching coaches [extreme programming]
- 2003
-
Ingår i: Extreme Programming and Agile Processes in Software Engineering. 4th International Conference, XP 2003. Proceedings (Lecture Notes in Computer Science Vol.2675). - 3540402152 ; , s. 154-160
-
Konferensbidrag (refereegranskat)abstract
- We have developed a tandem of undergraduate courses for teaching XP and coaching of XP teams. This paper focuses on the coaching course and the coaching practices we have developed. The tandem of courses enables us to give a challenging and interesting course for the coaches, and, at the same time, allows us to afford on-site coaches for the younger students, providing them with a high quality environment for learning XP. We also describe our experiences from the first instance of the courses and how we have tackled the bootstrapping problem
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| 29. |
- Hedin, Görel, et al.
(författare)
-
Introducing Software Engineering by means of Extreme Programming
- 2003
-
Ingår i: 25th International Conference on Software Engineering, 2003. Proceedings.. - 076951877X ; , s. 586-593
-
Konferensbidrag (refereegranskat)abstract
- This paper reports on experience from teaching basic software engineering concepts by using Extreme Programming in a second year undergraduate course taken by 107 students. We describe how this course fits into a wider programme on software engineering and technology and report our experience from running and improving the course. Particularly important aspects of our setup includes team coaching (by older students) and "team-in-one-room". Our experience so far is very positive and we see that students get a good basic understanding of the important concepts in software engineering, rooted in their own practical experience.
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| 30. |
- Hedin, Görel, et al.
(författare)
-
Tandem courses – students coaching students
- 2006
-
Ingår i: [Host publication title missing].
-
Konferensbidrag (refereegranskat)abstract
- Teamwork and project participation are essential skills for professional software engineers. To be able to give large groups of students adequate opportunities to learn such skills at a reasonable teaching cost, we have developed two courses that work in tandem: a team programming course taken by about 100 students, and a coaching course taken by about 20 students. In this paper, we describe our view of how these courses should be integrated within the engineering curriculum and our experiences of running them for five years. Important aspects of our set up include co-location during development, fixed working hours, and guided reflection exercises for both coaches and developers. The projects are run as role-playing games where teachers acting as customers provide opportunities for negotiation and the making of commitments. Our experience so far is very positive, and we see that students get a good basic understanding of the important concepts in software engineering, rooted in their own practical experience.
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| 31. |
- Hedin, Görel, et al.
(författare)
-
Teaching extreme programming to large groups of students
- 2005
-
Ingår i: Journal of Systems and Software. - : Elsevier BV. - 0164-1212. ; 74:2, s. 133-146
-
Tidskriftsartikel (refereegranskat)abstract
- We find the extreme programming methodology highly suitable for introducing undergraduate students to software engineering. To be able to apply this methodology at a reasonable teaching cost for large student groups, we have developed two courses that work in tandem: a team programming course taken by more than 100 students, and a coaching course taken by around 25 students. In this paper we describe our view of how extreme programming fits into the software engineering curriculum, our approach to teaching it, and our experiences, based on two years of running these courses. Particularly important aspects of our set up include team coaching (by older students), fixed working hours, and colocation during development. Our experiences so far are very positive, and we see that students get a good basic understanding of the important concepts in software engineering, rooted in their own practical experience.
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| 32. |
- Hedin, H, et al.
(författare)
-
A cost analysis of three methods of treating femoral shaft fractures in children : A comparison of traction in hospital, traction in hospital/home and external fixation
- 2004
-
Ingår i: Acta Orthopaedica Scandinavica. - : Medical Journals Sweden AB. - 0001-6470. ; 75:3, s. 241-248
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: There is no consensus as to which is best treatment of femoral fractures in children. Patients and methods: We performed a cost analysis comparing three treatments of femoral shaft fractures in children aged 3-15 years at 3 hospitals during the same period (1993-2000). The analysis included total medical costs and costs for the care provider and were calculated from the time of injury up to 1 year. Results: At hospital 1, treatment consisted of external fixation and early mobilization. At hospital 2, the treatment was skin or skeletal traction in hospital for 1-2 weeks, followed by home traction. At hospital 3, treatment was skin or skeletal traction in hospital until the fracture healed. Results: The average total costs per patient were EUR 10,000 at hospital 1, EUR 23,000 at hospital 2, and EUR 38,000 at hospital 3. Interpretation: The main factor for determining the cost of treatment was the number of days in hospital, which was lower in children treated with external fixation.
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| 33. |
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| 34. |
- Hedin, Hanne, 1948-
(författare)
-
External Fixation of Femoral Fractures in Children : Clinical, radiological and functional outcome and cost analysis
- 2003
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this thesis was to evaluate the outcome when treating children for displaced femoral fractures with external fixation.In a consecutive and prospective study during the period 1993-2000, 96 children aged 3-15 years with 98 displaced femoral fractures were treated with external fixation and early mobilisation. The mean age was 8.1 years, the mean hospital stay was 8.7 days and the mean treatment time was 61 days. All fractures healed. Minor complications included pin tract infections (18%), clinical insignificant malunions, heterotopic ossification and two re-reductions. Major complications (6%) included two re-fractures after significant trauma and three plastic deformations after premature fixator removal leading to an osteotomy.Radiological evaluation was performed up to one year for the whole group and for a subgroup up to two years. The evaluation showed that malunions were few and prone to remodelling almost completely. Although the fractures were fixated without shortening, as recommended earlier, the overgrowth was far less than expected.Isokinetic muscle strength was measured in both hamstrings and quadriceps in 31 of the patients and compared with 31 matched children without previous injury to the legs. Early mobilisation seems to prevent residual muscle weakness previously shown after treatment with traction or cast for femoral fractures in children.A cost analysis was performed, comparing three different treatment modalities of femoral shaft fractures: traction in hospital, traction in hospital/at home and external fixation. The analysis included both total medical costs and costs for the care provider. The most important factors were days spent at the hospital and the sick leave for the care provider. Treatment that can minimise these factors will contribute strongly to a lowering of health care costs.Conclusion: External fixation of displaced femoral fractures in children can be used as standard treatment in children aged 3-15 years. The treatment provides satisfactory results with a low rate of major complications. Early mobilisation seems to prevent residual muscle weakness. The treatment reduce the number of days in hospital and the number of days of sick leave for the care provider and contributes strongly to lowering health care costs.
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| 35. |
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| 36. |
- Hedin, Lars
(författare)
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Effects of recoil on shake-up spectra in metals
- 1980
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Ingår i: Physica Scripta. - 0031-8949. ; 21:304, s. 477-480
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Tidskriftsartikel (refereegranskat)abstract
- An infinite summation method is used to obtain the intrinsic photoemission spectrum of a conduction electron in the sudden limit. It is predicted that an electron at the bottom of the conduction band should have an asymmetry index comparable to that of a core electron and that the strengths of its plasmon satellites should be similar to those of a core electron. The width of their plasmon satellites, however, should become smaller under the influence of recoil. In essence, the results show that the exchange-correlation hole left after a photoemitted conduction electron has a very similar effect as the core hole left after a photoemitted core electron. Use of synchrotron radiation gives high enough a resolution to make possible the verification of these effects
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| 37. |
- Hedin, Lars
(författare)
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Electron correlation: keeping close to an orbital description
- 1995
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Ingår i: International Journal of Quantum Chemistry. - : Wiley. - 0020-7608 .- 1097-461X. ; 56:5, s. 445-452
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Tidskriftsartikel (refereegranskat)abstract
- This article deals with excited-state properties and spectroscopies which probe them. We argue that the orbitals obtained in local density theory form an excellent basis for discussing excited states and that the self-energy operator (or optical potential) associated with one-electron-type excited states is closely diagonal in such a basis. This diagonality often leads to considerable simplifications. We also discuss the reasons for the successes of the “GW-approximation” for the optical potential in predicting excited states. We further discuss a recent approach to calculate spectroscopic data. In particular, we present explicit results of this approach to photoelectron emission. The approach treats correlations within the target exactly but neglects some terms in the coupling between target and probe electron (=the photoemitted electron). This leads to closed expressions which exhibit a number of qualitative features. One is the cancellation of intrinsic and extrinsic losses at threshold excitation. Another is the broadening of the quasi-particles; we have energy-broadening for the occupied states but broadening through decaying wave functions for unoccupied states.(25 refs)
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| 38. |
- Hedin, Lars, et al.
(författare)
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External losses in photoemission from strongly correlated quasi-two-dimensional solids
- 2001
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Ingår i: Physical Review B. - 1550-235X. ; 64:11
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Tidskriftsartikel (refereegranskat)abstract
- Expressions are derived for photoemission, which allow experimental electron energy loss data to be used for estimating losses in photoemission. The derivation builds on new results for dielectric response and mean free paths of strongly correlated systems of two-dimensional layers. Numerical evaluations are made for Bi2Sr2CaCu2O8 (Bi2212) by using a parametrized loss function. The mean free path for Bi2212 is calculated and found to be substantially larger than obtained by Norman et al. [Phys. Rev. B 59, 11 191 (1999)] in a recent paper. The photocurrent is expressed as the convolution of the intrinsic approximation for the current from a specific two-dimensional layer with an effective loss function. This effective loss function is the same as the photocurrent from a core level stripped of the dipole matrix elements. The observed current is the sum of such currents from the first few layers. The correlation within one layer is considered as a purely two-dimensional (2D) problem separate from the embedding three-dimensional (3D) environment. When the contribution to the dielectric response from electrons moving in 3D is taken as diagonal in q space, its effect is just to replace bare Coulomb potentials in the (3D) coupling between the 2D layers with dynamically screened ones. The photoelectron from a specific CuO layer is found to excite low-energy acoustic plasmon modes due to the coupling between the CuO layers. These modes give rise to an asymmetric power-law broadening of the photocurrent an isolated two-dimensional layer would have given. We define an asymmetry index where a contribution from a Luttinger line shape is additive to the contribution from our broadening function. Already the loss effect considered here gives broadening comparable to what is observed experimentally. Our theory is not related to the loss mechanism recently discussed by Joynt [R. Joynt, Science 284, 777 (1999); R. Haslinger and R. Joynt, J. Electron Spectrosc. Relat. Phenom. 117-118, 31 (2001)] which adds additional broadening beyond what we calculate. A superconductor with a gapped loss function is predicted to have a peak-dip-hump line shape similar to what has been observed, and with the same qualitative behavior as predicted in the recent work by Campuzano et al. [Phys. Rev. Lett. 83, 3709 (1999)].(35 refs)
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| 39. |
- Hedin, Lars, et al.
(författare)
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Extrinsic and intrinsic processes in EXAFS
- 1989
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Ingår i: Physica B. - : Elsevier BV. - 0921-4526. ; 158, s. 344-346
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Konferensbidrag (refereegranskat)abstract
- The author extends the ideas of Bardyszewski and Hedin (1987) to treat EXAFS. He summarises the theory, adds new viewpoints and extends the theory.
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| 40. |
- Hedin, Lars, et al.
(författare)
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Hedin, Lars
- 1988
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Ingår i: Lärda Lund A-Ö. ; , s. 79-79
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Bokkapitel (populärvet., debatt m.m.)
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| 41. |
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| 42. |
- Hedin, Lars, et al.
(författare)
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ON THE THEORY OF COINCIDENCE SPECTRA
- 1984
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Ingår i: Annals of the Israel Physical Society. - 0309-8710. ; 6, s. 311-315
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Konferensbidrag (refereegranskat)abstract
- We discuss spectra where both a primary photoelectron and a secondary decay particle are measured. We point out the striking similarity with threshold-excited emission spectra and predict resonant peaks analoguous to those found in resonant photoemission.
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| 43. |
- Hedin, Lars
(författare)
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Optical potentials and damped one-electron functions in photoemission and electron scattering
- 1990
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 51, s. 91-102
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Tidskriftsartikel (refereegranskat)abstract
- Recently a new approach to photoemission, EXAFS and electron scattering has been developed. The correlations between target electrons are separated from the active electron-target electron correlations, and the damping effects are coming out explicitly. The theory uses van Hove diagonal Green's functions and projection operator techniques, not the usual diagram expansions. By omitting from the start terms in the Hamiltonian which lead to reabsorption of the active electron (photoelectron or scattered electron), remarkably simple expressions are obtained. These expressions contain optical potentials which damp the electron propagation, and “fluctuation potentials” which determine the inelastic scattering. The fluctuation potentials also appear in the expressions for the optical potentials. On the RPA level of approximation the fluctuation potentials are obtained from the dielectric response function of the target. The theory is quite general, but its main advantages are for extended systems, where the damped propagators and damped one electron functions are important effects. The present theory should make it possible to quantitatively attack a number of correlation effects in different spectroscopies.
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| 44. |
- Hedin, Lars
(författare)
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Properties of electron self-energies and their role in electron spectroscopies
- 1991
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; A308:1-2, s. 169-177
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Tidskriftsartikel (refereegranskat)abstract
- The GW approximation for the self-energy connected with the one-electron Green's function has been very successful in predicting band structures for a large class of semiconductors and insulators. The physical basis for this approximation and general features of its nonlocality are discussed, as well as possible improvements. Besides quasiparticle energies the self-energy also gives the intrinsic part of the photoelectron spectrum. In general, however, a full description of experimental spectra measured with synchrotron radiation, such as photoemission, Auger spectra and EXAFS, cannot be given by the one-electron Green's function. A new theoretical approach to synchrotron radiation spectroscopies is given in terms of the coupling functions involved in the GW approximation and on-the-energy-shell one-electron Green's functions.(14 refs)
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| 45. |
- Hedin, Lars, et al.
(författare)
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Sudden approximation in photoemission and beyond
- 2002
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 124:2-3, s. 289-315
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Tidskriftsartikel (refereegranskat)abstract
- The conditions behind sudden approximation are critically examined. The fuzzy band expression is derived in detail from first principles. We go beyond the sudden approximation to account for both extrinsic losses and interference effects. In an extension of earlier work we discuss both core and valence satellites including both intrinsic and extrinsic amplitudes, and high energy excitations as well as low energy electron-hole pairs. We show how the extrinsic losses in photoemission can be connected with the electron energy loss function. This is achieved by three approximations, to connect the dynamically screened potential in the bulk solid to the loss function, to account for the surface, and lastly to extrapolate zero momentum loss data to include dispersion. The extrinsic losses are found to be weak for small loss energies. For larger loss energies the extrinsic losses can be strong and have strong interference with the intrinsic losses depending on the nature of the solid. The transition from the adiabatic to the sudden regime is discussed for atoms and localized systems and compared with the situation for solids. We argue that in solids for photoelectron energies above some 10 eV the external losses are mainly connected with spacially extended excitations. We discuss strongly correlated quasi-two-dimensional solids with Bi2212 as example, and find an asymmetric broadening of the main peak from shake up of acoustic three-dimensional plasmons. In the superconducting state the loss function is assumed to have a gap, which then leads to a peak-dip-hump structure in the photoemission spectrum. This structure is compared with a corresponding structure in tunneling. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 46. |
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| 47. |
- Hedin-Skogman, Barbro, et al.
(författare)
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Acute facial palsy in children - a 2-year follow-up study with focus on Lyme neuroborreliosis
- 2003
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Ingår i: International Journal of Pediatric Otorhinolaryngology. - 0165-5876. ; 67:6, s. 597-602
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Acute facial palsy in children is believed to be a rather benign neurological condition. Follow-up-studies are sparse, especially including a thorough otoneurological re-examination. The aim of this study was to examine children with a history of facial palsy in order to register the incidence of complete recovery and the severity and nature of sequelae. We also wanted to investigate whether there was a correlation between sequelae and Lyme Borreliosis, treatment or other health problems. Methods: Twenty-seven children with a history of facial palsy were included. A re-examination was performed by an Ear-Nose-Throat (ENT) specialist 1–2.9 years (median 2) after the acute facial palsy. The otoneurological examination included grading the three branches of the facial nerve with the House-Brackman score, otomicroscopy and investigation with Frenzel glasses. A paediatrician interviewed the families. Medical files were analysed. Result: The incidence of complete recovery was 78% at the 2-year follow-up. In six out of 27 children (22%), the facial nerve function was mildly or moderately impaired. Four children reported problems with tear secretion and pronunciation. There was no correlation between sequelae after the facial palsy and gender, age, related symptoms, Lyme neuroborreliosis (NB), treatment, other health problems or performance. Conclusion: One fifth of children with an acute facial palsy get a permanent dysfunction of the facial nerve. Other neurological symptoms or health problems do not accompany the sequelae of the facial palsy. Lyme NB or treatment seems to have no correlation to clinical outcome. Factors of importance for complete recovery after an acute facial palsy are still not known.
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| 48. |
- Ivarsson, Karin, 1970, et al.
(författare)
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The chemotactic cytokine interleukin-8--a cyst fluid marker for malignant epithelial ovarian cancer?
- 1998
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Ingår i: Gynecologic oncology. - : Elsevier BV. - 0090-8258. ; 71:3, s. 420-3
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Tidskriftsartikel (refereegranskat)abstract
- Due to the difficulties in separating malignant and benign ovarian cysts by transvaginal ultrasound and other techniques, there is a need for biochemical markers in serum or cyst fluids. In the present study we have evaluated the levels of the chemokine interleukin-8 (IL-8) in ovarian cysts. IL-8 is known to be expressed in the normal ovary and to influence proliferation and angiogenesis of several nonovarian types of tumors. Cyst fluids from benign (n = 15) and malignant (n = 13) ovarian tumors were analyzed. The levels of IL-8 were found to be significantly (13-fold) higher in cyst fluids from malignant tumors (18.1 +/- 7.5 ng/ml; mean +/- SE) compared to benign cysts (1.3 +/- 0.7 ng/ml). The plasma levels of IL-8 were considerably lower (2.9 and 0.3% of levels in benign and malignant cyst fluids, respectively) than in cyst fluids. No difference in the plasma levels of patients with benign or malignant tumor could be detected. In contrast, the levels of CA 125 were significantly higher in plasma of patients with malignant disease with the inverse relation in cyst fluids. In conclusion, the levels of IL-8 are markedly elevated in cyst fluid from malignant tumors compared to benign. This specific increase indicates a role for this cytokine in ovarian tumor biology.
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| 49. |
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| 50. |
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