| 1. |
- Bengtsson, Anders K.H., et al.
(author)
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Particles, superparticles and twistors
- 1987
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In: Phys. Rev. D36 (1987) 1766.
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Journal article (peer-reviewed)abstract
- The covariant Green-Schwarz action for a superstring has never been quantized covariantly. The physics behind this is discussed. We then consider the corresponding point-particle action in four dimensions, and write down a master action from which it can be obtained as a gauge choice: the ‘‘space-time gauge.’’ There is also a ‘‘twistor gauge,’’ in which covariant quantization is straightforward (as noted previously by Shirafuji).
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| 2. |
- Jönsen, Andreas, et al.
(author)
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Direct and indirect costs for systemic lupus erythematosus in Sweden. A nationwide health economic study based on five defined cohorts
- 2016
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In: Seminars in Arthritis & Rheumatism. - : Elsevier BV. - 0049-0172 .- 1532-866X. ; 45:6, s. 684-690
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Research review (peer-reviewed)abstract
- Objectives: The main objectives of this study were to calculate total costs of illness and cost -driving disease features among patients with systemic lupus erythematosus (SLE) in Sweden. Methods: Five cohorts of well-defined SLE patients, located in different parts of the country were merged. Incident and prevalent cases from 2003 through 2010 were included. The American College of Rheumatology (ACR) classification criteria was used. From the local cohorts, data on demographics, disease activity (SLEDAI 2K), and organ damage (SDI) were collected. Costs for inpatient care, specialist outpatient care and drugs were retrieved from national registries at the National Board of Health and Welfare. Indirect costs were calculated based on sickness leave and disability pensions from the Swedish Social Insurance Agency. Results: In total, 1029 SLE patients, 88% females, were included, and approximately 75% were below 65 years at the end of follow-up, and thus in working age. The mean number of annual specialist physician visits varied from six to seven; mean annual inpatient days were 3.1-3.6, and mean annual sick leave was 123-148 days, all per patient. The total annual cost was 208,555 SEK ($33,369 = 22,941(sic)), of which direct cost was 63,672kr ($10,188 = 7004(sic)) and the indirect cost was 144,883 SEK ($23,181 = 15,937(sic)), all per patient. The costs for patients with short disease duration were higher. Higher disease activity as measured by a SLEDAI 2K score > 3 was associated with approximately 50% increase in both indirect and direct costs. Damage in the neuropsychiatric and musculoskeletal domains were also linked to higher direct and indirect costs, while organ damage in the renal and ocular systems increased direct costs. Conclusion: Based on this study and an estimate of slightly more than 6000 SLE patients in Sweden, the total annual cost for SLE in the country is estimated at $188 million (= 129.5 million (sic)). Both direct (30%) and indirect costs (70%) are substantial. Medication accounts for less than 10% of the total cost. The tax paid national systems for health care and social security in Sweden ensure equal access to health care, sick leave reimbursements, and disability pensions nationwide. Our extrapolated annual costs for SLE in Sweden are therefore the best supported estimations thus far, and they clearly underline the importance of improved management, especially to reduce the indirect costs. (C) 2016 Elsevier Inc. All rights reserved.
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| 3. |
- Jönsson, K. Ingemar, 1959-, et al.
(author)
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Ekologisk kompensation som styrmedel i kommunal planering
- 2021
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Reports (other academic/artistic)abstract
- Projektet har undersökt erfarenheter av och förutsättningar för att tillämpa ekologisk kompensation inom ramen för den kommunala planeringen. Inom olika delstudier har projektet undersökt ekologisk kompensation som styrmedel, tillämpningen av skadelindringshierarkin, utformningen av kompensationsmodeller och rutiner, användningen av olika modeller för beräkning av förluster och vinster inom kompensationsprojekt, samt allmänhetens preferenser för olika kompensationsalternativ. Projektet har genomförts i nära samarbete med Helsingborgs och Lomma kommun, och Kommunförbundet Skåne har varit projektets kommunikationspartner och arrangör av flera större möten och workshopar med tjänstemän från många kommuner i Skåne. ...
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| 4. |
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| 5. |
- Andersson, David, et al.
(author)
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States that are far from being stabilizer states
- 2015
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In: Journal of Physics A. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 48:34
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Journal article (peer-reviewed)abstract
- Stabilizer states are eigenvectors of maximal commuting sets of operators in a finite Heisenberg group. States that are far from being stabilizer states include magic states in quantum computation, MUB-balanced states, and SIC vectors. In prime dimensions the latter two fall under the umbrella of minimum uncertainty states (MUSs) in the sense of Wootters and Sussman. We study the correlation between two ways in which the notion of ` far from being a stabilizer state' can be quantified. Two theorems valid for all prime dimensions are given, as well as detailed results for low dimensions. In dimension 7 we identify the MUB-balanced states as being antipodal to the SIC vectors within the set of MUS, in a sense that we make definite. In dimension 4 we show that the states that come closest to being MUS with respect to all of the six stabilizer MUBs are the fiducial vectors for Alltop MUBs.
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| 6. |
- Andersson, H. Ingemar, 1950-
(author)
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Chronic pain : epidemiological studies in a general population
- 1998
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Doctoral thesis (other academic/artistic)abstract
- The aim was to study the epidemiology of chronic pain (> 3 months duration) and factors associated to pain prevalence, prognosis, health care and medication in a general population. A cross-sectional mailed survey to a random population sample (n = 1806) was followed by a clinical examination and a prospective study of three selected groups. Pain related diagnoses from primary health care was monitored and compared with pain prevalence. The most important findings were: - a high total prevalence of chronic pain, 55.2%, without gender difference but varying by age and socioeconomic level. About one fourth (12.8%) reported high pain intensity and functional impairments. Women experienced pain at more locations and with higher intensity. - in a multivariate analysis increasing age, female gender, low education, high work strain, depression and insomnia were associated with chronic pain. - widespread pain showed a worse 2- year prognosis compared with neck shoulder pain. - musculoskeletal location of pain dominated, myalgia and myofascial pain being the most common symptom descriptions. - co-morbidity with chronic pain was common. More hypertensives and an increased level of serum uric acid associated to widepread pain indicated possible metabolic connections to pain. - smoking (current and previous) was associated with low-back and widespread pain. - chronic pain had a substantial influence of primary health care-seeking and medication; high pain intensity being the most important predictor of care and medication. - pain related diagnoses in primary health care increased between 1987 and 1996. Chronic pain, mainly with musculoskeletal location, is a community health problem. A multi-factorial approach in prevention and treatment on the basis of present knowledge is necessary.
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| 7. |
- Andersson, Ole, et al.
(author)
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Clifford tori and unbiased vectors
- 2017
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In: Reports on mathematical physics. - : Elsevier. - 0034-4877 .- 1879-0674. ; 79:1, s. 33-51
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Journal article (peer-reviewed)abstract
- The existence problem for mutually unbiased bases is an unsolved problem in quantum information theory. A related question is whether every pair of bases admits vectors that are unbiased to both. Mathematically this translates to the question whether two Lagrangian Clifford tori intersect, and a body of results exists concerning it. These results are however rather weak from the point of view of the first problem. We make a detailed study of how the intersections behave in the simplest nontrivial case, that of complex projective 2-space (the qutrit), for which the set of pairs of Clifford tori can be usefully parametrized by the unistochastic subset of Birkhoff's polytope. Pairs that do not intersect transversally are located. Some calculations in higher dimensions are included to see which results are special to the qutrit.
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| 8. |
- Andersson, Ole, et al.
(author)
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Geometric phases for mixed states of the Kitaev chain
- 2016
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In: Philosophical Transactions. Series A. - : The Royal Society. - 1364-503X .- 1471-2962. ; 374:2069
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Journal article (peer-reviewed)abstract
- The Berry phase has found applications in building topological order parameters for certain condensed matter systems. The question whether some geometric phase for mixed states can serve the same purpose has been raised, and proposals are on the table. We analyze the intricate behaviour of Uhlmann’s geometric phase in the Kitaev chain at finite temperature, and then argue that it captures quite different physics from that intended. We also analyze the behaviour of a geometric phase introduced in the context of interferometry. For the Kitaev chain, this phase closely mirrors that of the Berry phase, and we argue that it merits further investigation.
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| 9. |
- Andersson, Ole
(author)
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Holonomy in Quantum Information Geometry
- 2018
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Licentiate thesis (other academic/artistic)abstract
- In this thesis we provide a uniform treatment of the two most popular non-adiabatic geometric phases for dynamical systems of mixed quantum states, namely those of Uhlmann and of Sjöqvist et al. We develop a holonomy theory for the latter which we also relate to the already existing theory for the former. This makes it clear what the similarities and differences between the two geometric phases are. We discuss and motivate constraints on the two phases. Furthermore, we discuss some topological properties of the holonomy of `real' quantum systems, and we introduce higher-order geometric phases for not necessarily cyclic dynamical systems of mixed states. In a final chapter we apply the theory developed for the geometric phase of Sjöqvist et al. to geometric uncertainty relations, including some new "quantum speed limits''.
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| 10. |
- Andersson, Ole, et al.
(author)
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Self-testing properties of Gisin's elegant Bell inequality
- 2017
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In: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 96:3
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Journal article (peer-reviewed)abstract
- An experiment in which the Clauser-Horne-Shimony-Holt inequality is maximally violated is self-testing (i.e., it certifies in a device-independent way both the state and the measurements). We prove that an experiment maximally violating Gisin's elegant Bell inequality is not similarly self-testing. The reason can be traced back to the problem of distinguishing an operator from its complex conjugate. We provide a complete and explicit characterization of all scenarios in which the elegant Bell inequality is maximally violated. This enables us to see exactly how the problem plays out.
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| 11. |
- Appleby, D. M., et al.
(author)
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GALOIS UNITARIES, MUTUALLY UNBIASED BASES, AND MUB-BALANCED STATES
- 2015
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In: Quantum information & computation. - 1533-7146. ; 15:15-16, s. 1261-1294
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Journal article (peer-reviewed)abstract
- A Galois unitary is a generalization of the notion of anti-unitary operators. They act only on those vectors in Hilbert space whose entries belong to some chosen number field. For Mutually Unbiased Bases the relevant number field is a cyclotomic field. By including Galois unitaries we are able to remove a mismatch between the finite projective group acting on the bases on the one hand, and the set of those permutations of the bases that can be implemented as transformations in Hilbert space on the other hand. In particular we show that there exist transformations that cycle through all the bases in all dimensions d - p(n) where p is an odd prime and the exponent n is odd. (For even primes unitary MUB-cyclers exist.) These transformations have eigenvectors, which are MUB-balanced states (i.e. rotationally symmetric states in the original terminology of Wootters and Sussman) if and only if d = 3 modulo 4. We conjecture that this construction yields all such states in odd prime power dimension.
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| 12. |
- Appleby, D.M., et al.
(author)
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Systems of Imprimitivity for the Clifford Group
- 2014
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In: Quantum information & computation. - : Rinton Press. - 1533-7146. ; 14:3-4, s. 339-360
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Journal article (peer-reviewed)abstract
- It is known that if the dimension is a perfect square the Clifford group can be represented by monomial matrices. Another way of expressing this result is to say that when the dimension is a perfect square the standard representation of the Clifford group has a system of imprimitivity consisting of one dimensional subspaces. We generalize this result to the case of an arbitrary dimension. Let k be the square-free part of the dimension. Then we show that the standard representation of the Clifford group has a system of imprimitivity consisting of k-dimensional subspaces. To illustrate the use of this result we apply it to the calculation of SIC-POVMs (symmetric informationally complete positive operator valued measures), constructing exact solutions in dimensions 8 (hand-calculation) as well as 12 and 28 (machine-calculation).
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| 13. |
- Appleby, D. M., et al.
(author)
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The monomial representations of the Clifford group
- 2012
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In: Quantum information & computation. - : Rinton Press, Inc.. - 1533-7146. ; 12:5-6, s. 404-431
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Journal article (peer-reviewed)abstract
- We show that the Clifford group-the normaliser of the Weyl-Heisenberg group-can be represented by monomial phase-permutation matrices if and only if the dimension is a square number. This simplifies expressions for SIC vectors, and has other applications to SICs and to Mutually Unbiased Bases. Exact solutions for SICs in dimension 16 are presented for the first time.
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| 14. |
- Appleby, Marcus, et al.
(author)
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Dimension towers of SICs. I. Aligned SICs and embedded tight frames
- 2017
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In: Journal of Mathematical Physics. - : AIP Publishing. - 0022-2488 .- 1089-7658. ; 58:11
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Journal article (peer-reviewed)abstract
- Algebraic number theory relates SIC-POVMsin dimension d > 3 to those in dimension d(d - 2). We define a SIC in dimension d(d - 2) to be aligned to a SIC in dimension d if and only if the squares of the overlap phases in dimension d appear as a subset of the overlap phases in dimension d(d - 2) in a specifiedway. We give 19 (mostly numerical) examples of aligned SICs. We conjecture that given any SIC in dimension d, there exists an aligned SIC in dimension d(d - 2). In all our examples, the aligned SIC has lower dimensional equiangular tight frames embedded in it. If d is odd so that a natural tensor product structure exists, we prove that the individual vectors in the aligned SIC have a very special entanglement structure, and the existence of the embedded tight frames follows as a theorem. If d - 2 is an odd prime number, we prove that a complete set of mutually unbiased bases can be obtained by reducing an aligned SIC to this dimension.
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| 15. |
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| 16. |
- Badziag, Piotr, et al.
(author)
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Pentagrams and Paradoxes
- 2011
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In: FOUNDATIONS OF PHYSICS. - : Springer Science Business Media. - 0015-9018 .- 1572-9516. ; 41:3, s. 414-423
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Journal article (peer-reviewed)abstract
- Klyachko and coworkers consider an orthogonality graph in the form of a pentagram, and in this way derive a Kochen-Specker inequality for spin 1 systems. In some low-dimensional situations Hilbert spaces are naturally organised, by a magical choice of basis, into SO(N) orbits. Combining these ideas some very elegant results emerge. We give a careful discussion of the pentagram operator, and then show how the pentagram underlies a number of other quantum "paradoxes", such as that of Hardy.
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| 17. |
- Barros e Sa, Nuno, et al.
(author)
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Families of complex Hadamard matrices
- 2013
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In: Linear Algebra and its Applications. - : Elsevier BV. - 0024-3795 .- 1873-1856. ; 438:7, s. 2929-2957
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Journal article (peer-reviewed)abstract
- What is the dimension of a smooth family of complex Hadamard matrices including the Fourier matrix? We address this problem with a power series expansion. Studying all dimensions up to 100 we find that the first order result is misleading unless the dimension is 6, or a power of a prime. In general the answer depends critically on the prime number decomposition of the dimension. Our results suggest that a general theory is possible. We discuss the case of dimension 12 in detail, and argue that the solution consists of two 13-dimensional families intersecting in a previously known 9-dimensional family. A precise conjecture for all dimensions equal to a prime times another prime squared is formulated.
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| 18. |
- Bengtsson, H, et al.
(author)
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Prevalence of abdominal aortic aneurysm in the offspring of patients dying from aneurysm rupture
- 1992
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In: British Journal of Surgery. - : Oxford University Press (OUP). - 1365-2168 .- 0007-1323. ; 79:11, s. 1142-1143
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Journal article (peer-reviewed)abstract
- The prevalence of abdominal aortic aneurysm (AAA) is high in the brothers of patients with aneurysm. A genetic component in the development of AAA has, therefore, been postulated. In this study the offspring of patients who had died from AAA rupture were invited to undergo ultrasonography of the abdominal aorta. The attendance rate was 69 per cent. Thirty-nine sons of median age 60 (range 45-75) years and 23 daughters of median age 62 (range 42-80) years were examined. Abdominal aortic dilatation was found in eight men and one woman. The presence of aortic dilatation in these nine cases was not related to age, hypertension, smoking or symptoms of occlusive arterial disease. It is concluded that the sons of those who have died from ruptured AAA constitute a high-risk group for the development of this condition and should be considered for further screening.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Bengtsson, Ingemar
(author)
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A Kochen-Specker Inequality
- 2009
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In: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 1101, s. 241-245
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Journal article (other academic/artistic)abstract
- I review a paper by Klyachko, Can, Binicioğlu, and Shumovsky, and explain a little of the background as I see it
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| 23. |
- Bengtsson, Ingemar, et al.
(author)
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A Kochen-Specker inequality for a SIC
- 2012
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In: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 376:4, s. 374-376
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Journal article (peer-reviewed)abstract
- Yu and Oh (eprint) [1] have given a state-independent proof of the Kochen–Specker theorem in three dimensions using only 13 rays. The proof consists of showing that a non-contextual hidden variable theory necessarily leads to an inequality that is violated by quantum mechanics. We give a similar proof making use of 21 rays that constitute aSIC (symmetric informationally-complete positive operator-valued measure) and a complete set of MUB (mutually unbiased bases). A theory-independent inequality is also presented using the same 21 rays, as required for experimental tests of contextuality.
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| 24. |
- Bengtsson, Ingemar
(author)
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A market for citizenships: Should citizenship be commodified?
- 2023
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In: Kyklos. - 0023-5962. ; 76:4, s. 705-723
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Journal article (peer-reviewed)abstract
- Starting from the assumption that citizenship is valuable private property that would be even more valuable if it were transferable, the paper explores the idea of commodification of citizenship. The paper provides arguments in favor of commodification of citizenship and recommendations to how the market for citizenship should be designed. A market for citizenships could result in an improved matching between employer and employee when citizens swap citizenship with each other. Successful States would issue new citizenships and thus provide the possibility for a greater share of the world population to live and work within the countries with the best institutions. The combined effect would be a higher global productivity. Market prices on citizenships would provide a robust indicator of institutional quality and thus provide politicians with information on voters´ preferences and it would also provide voters with information on the quality of the work of the government. The market value of a tradable citizenship is also found to be a promising candidate as tax base for a redistributive tax on a global level that could address some of the inherit inequality inherit in the current distribution of citizenships.
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| 25. |
- Bengtsson, Ingemar
(author)
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A Note on Trapped Surfaces in the Vaidya Solution
- 2009
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In: Physical Review D. Particles and fields. - 0556-2821 .- 1089-4918. ; 79:2, s. 024027-
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Journal article (peer-reviewed)abstract
- The Vaidya solution describes the gravitational collapse of a finite shell of incoherent radiation falling into flat spacetime and giving rise to a Schwarzschild black hole. There has been a question whether closed trapped surfaces can extend into the flat region (whereas closed outer trapped surfaces certainly can). For the special case of self-similar collapse we show that the answer is yes, if and only if the mass function rises fast enough.
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| 26. |
- Bengtsson, Ingemar, et al.
(author)
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A Toy Penrose Inequality and Its Proof
- 2016
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In: General Relativity and Gravitation. - : Springer Science and Business Media LLC. - 0001-7701 .- 1572-9532. ; 48:12
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Journal article (peer-reviewed)abstract
- We formulate and prove a toy version of the Penrose inequality. The formulation mimics the original Penrose inequality in which the scenario is the following: A shell of null dust collapses in Minkowski space and a marginally trapped surface forms on it. Through a series of arguments relying on established assumptions, an inequality relating the area of this surface to the total energy of the shell is formulated. Then a further reformulation turns the inequality into a statement relating the area and the outer null expansion of a class of surfaces in Minkowski space itself. The inequality has been proven to hold true in many special cases, but there is no proof in general. In the toy version here presented, an analogous inequality in (2+1)-dimensional anti-de Sitter space turns out to hold true.
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| 27. |
- Bengtsson, Ingemar, 1957-
(author)
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Algebraic units, anti-unitary symmetries, and a small catalogue of SICs
- 2020
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In: Quantum information & computation. - 1533-7146. ; 20:5&6, s. 400-417
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Journal article (peer-reviewed)abstract
- In complex vector spaces maximal sets of equiangular lines, known as SICs, are related to real quadratic number fields in a dimension dependent way. If the dimension is of the form n^2+3, the base field has a fundamental unit of negative norm, and there exists a SIC with anti-unitary symmetry. We give eight examples of exact solutions of this kind, for which we have endeavoured to make them as simple as we can---as a belated reply to the referee of an earlier publication, who claimed that our exact solution in dimension 28 was too complicated to be fit to print. An interesting feature of the simplified solutions is that the components of the fiducial vectors largely consist of algebraic units.
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| 28. |
- Bengtsson, Ingemar, et al.
(author)
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Anti-de Sitter Quotients: When Are They Black Holes?
- 2008
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In: Classical and quantum gravity. - 0264-9381 .- 1361-6382. ; 25, s. 095019-
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Journal article (peer-reviewed)abstract
- e point out that the BTZ black holes, and their relatives, can be defined in a cleaner way than they originally were. The covering space can be taken to be anti-de Sitter space, period, while splits up into components due to Misner singularities. Our definition permits us to choose between two conflicting claims concerning BTZ black holes in (3 + 1) dimensions.
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| 29. |
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| 30. |
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| 31. |
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| 32. |
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| 33. |
- Bengtsson, Ingemar, et al.
(author)
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Black hole lattices under the microscope
- 2018
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In: Classical and quantum gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 35:14
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Journal article (peer-reviewed)abstract
- It is known how to choose initial data for Einstein's equations describing an arbitrary number of black holes at a moment of time symmetry. This idea has been used to give insight into the cosmological averaging problem. We study the local curvature of the initial data space, for configurations of 8, 120, or 600 black holes obtained by choosing points either regularly or randomly on a 3-sphere. We conclude that the asymptotic regions are remarkably close to that of Schwarzschild, while the region in between shows interesting behaviour. The cosmological back reaction as defined in the recent literature is actually a bit smaller for the random configurations.
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| 34. |
- Bengtsson, Ingemar, et al.
(author)
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Black holes : Their large interiors
- 2015
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In: Modern Physics Letters A. - 0217-7323 .- 1793-6632. ; 30:21
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Journal article (peer-reviewed)abstract
- Christodoulou and Rovelli (CR) have remarked on the large interiors possessed by static black holes. We amplify their remarks, and extend them to the spinning case.
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| 35. |
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| 36. |
- Bengtsson, Ingemar, et al.
(author)
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Bostadspolitiken
- 2018
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In: Ingemar Ståhl - en ekonom för blandekonomin. - 9789175043371 ; , s. 85-94
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Book chapter (pop. science, debate, etc.)
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Bengtsson, Ingemar
(author)
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Central bank power is a matter of faith
- 2005
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Other publication (other academic/artistic)abstract
- This paper reconsiders how central banks get involved in the process of determining nominal variables such as market interest rates and inflation rates. It is argued that the traditional story deriving central bank power from its monopoly of issuing base money is flawed. That story - in its various guises - is based on the quantity equation. This equation, however, is only applicable in the hypothetical only-cash-world, i.e. in a world where all transactions has to be paid for with central bank issued notes and coins. Nevertheless, the vast majority of economists would agree that, in practice, central banks seem to influence interest and inflation rates. Here, we suggest that the explanation is that central banks have acquired a role as focal point for those variables. It is possible because interest setting is a coordination game, in which agents have to predict each others expectations.
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| 41. |
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| 42. |
- Bengtsson, Ingemar, et al.
(author)
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'Classical' Quantum States
- 2009
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In: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 80:2, s. 022319-
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Journal article (peer-reviewed)abstract
- We show that several classes of mixed quantum states in finite-dimensional Hilbert spaces which can be characterized as being, in some respect, "most classical" can be described and analyzed in a unified way. Among the states we consider are separable states of distinguishable particles, uncorrelated states of indistinguishable fermions and bosons, as well as mixed spin states decomposable into probabilistic mixtures of pure coherent states. The latter was the subject of the recent paper by Giraud et al. [Phys. Rev. A 78, 042112 (2008)], who showed that in the lowest-dimensional nontrivial case of spin 1, each such state can be decomposed into a mixture of eight pure states. Using our method, we prove that in fact four pure states always suffice.
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| 43. |
- Bengtsson, Ingemar, et al.
(author)
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Classics illustrated: limits of spacetimes
- 2014
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In: Classical and quantum gravity. - : IOP Publishing. - 0264-9381 .- 1361-6382. ; 31:20
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Journal article (peer-reviewed)abstract
- We carefully study the e→m and e→0 limits of the Reissner-Nordström spacetime using Geroch's definition of limits of spacetimes. This is implemented by embedding the one-parameter family of spacetimes in anti-de Sitter space, and as a result we obtain metrically correct Penrose diagrams. For e→m two distinct limits are studied.
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| 44. |
- Bengtsson, Ingemar, et al.
(author)
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Covariant superstrings do not admit covariant gauge fixing
- 1984
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Journal article (other academic/artistic)abstract
- The covariant action for superstrings is analysed by means of the Diracmethod, and the light front action is derived. The action gives riseto second class constraints which cannot be solved for in a covariant way. Covariant gauge fixing, in any conventional sense, cannot be applied, which leaves the question of covariant quantisationof the superstrings open. A similar statement holds for a masslesssupersymmetric point-particle.
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| 45. |
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| 46. |
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| 47. |
- Bengtsson, Ingemar, 1957-, et al.
(author)
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Dimension towers of SICS: II. Some constructions
- 2022
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In: Journal of Physics a-Mathematical and Theoretical. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 55:21
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Journal article (peer-reviewed)abstract
- A SIC is a maximal equiangular tight frame in a finite dimensional Hilbert space. Given a SIC in dimension d, there is good evidence that there always exists an aligned SIC in dimension d(d - 2), having predictable symmetries and smaller equiangular tight frames embedded in them. We provide a recipe for how to calculate sets of vectors in dimension d(d - 2) that share these properties. They consist of maximally entangled vectors in certain subspaces defined by the numbers entering the d dimensional SIC. However, the construction contains free parameters and we have not proven that they can always be chosen so that one of these sets of vectors is a SIC. We give some worked examples that, we hope, may suggest to the reader how our construction can be improved. For simplicity we restrict ourselves to the case of odd dimensions.
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| 48. |
- Bengtsson, Ingemar
(author)
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En ny social bostadspolitik? Nej, men en bra början.
- 2018
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In: Bostadspolitik.se.
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Journal article (pop. science, debate, etc.)abstract
- S-rapporten, ”en ny social bostadspolitik” levererar en bra problemanalys och flera goda målbeskrivningar men deras förslag orkar inte helt i mål, menar Ingemar Bengtsson, Universitetslektor vid Avdelningen för Fastighetsvetenskap, Lunds Universitet. Ingemar Bengtsson ifrågasätter gruppens allmänna strävan att samhället ska öka den samlade bostadskonsumtionen och efterlyser i följande kommentar mer fokus på prioriteringar och svar på hur det befintliga beståndet kan användas bättre.
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- Bengtsson, Ingemar
(author)
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Fastighetsvärdering - Om värdeteori och värderingsmetoder
- 2023. - 2
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Book (other academic/artistic)abstract
- Det här är en lärobok om hur fastigheter får sitt värde och hur detta värde kan bedömas. Med utgångspunkt i nationalekonomisk teori beskrivs en värdeteori för fastigheter som förklarar hur fastighetsvärden uppstår ur mänskliga behov. Det förklaras hur värdena också påverkas av hur fastigheters användning regleras i lag och politik. Från värdeteorin går boken över till värderingsteori och beskriver och diskuterar lämpliga metoder för att värdera olika typer av fastigheter. Denna röda tråd avslutas med två kapitel om värderingsmetod som beskriver hur värderingen går till i praktiken för tre vanliga värderingsobjekt: villor och bostadsrätter samt hyreshus för bostäder eller kontor. Utöver den röda tråden går författaren igenom nödvändiga fastighetsrelaterade begrepp och lönsamhetsbedömning av fastighetsinvesteringar.Denna reviderade och utökade upplaga av Fastighetsvärdering – om värdeteori och värderingsmetoder utgår från etablerad vetenskaplig teori och metod och vänder sig i första hand till högskolestuderande inom samhällsbyggnadssektorn, men också till yrkesverksamma och till politiska beslutsfattare och intresserade privatpersoner.
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