| 1. |
- Lastras-Martínez, L. F., et al.
(author)
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Reflectance difference spectroscopy of GaAs asymmetric surface quantum wells above the fundamental gap
- 1998
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In: Physica status solidi. A, Applied research. - 0031-8965 .- 1521-396X. ; 170:2, s. 317-321
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Journal article (peer-reviewed)abstract
- We report Reflectance Difference (RD) measurement on (001) GaAs surface quantum wells (QW) under Ultra High Vacuum (UHV) conditions from 1.7 to 5.0eV. The QW is embedded between an arsenic-rich reconstructed GaAs surface and an AlAs barrier. The samples, grown by MBE with a protective arsenic cap layer, were heated to 320 and 430°C to desorb the As layer and form c(4 x 4) and (2 x 4) surface reconstructions, respectively. By modifying the surface reconstructure, we are able to separate the contributions to the optical anisotropy from the surface region (mainly associated with the As dimers) from those originating below the surface.
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| 2. |
- Anoushirvani, B., et al.
(author)
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Gamma-ray bursts from primordial quark objects in space
- 1997
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In: Proceedings of the Joint Meeting of the Networks 'The Fundamental Structure of Matter' and 'Tests of the Electroweak Symmetry Breaking', Ouranoupolis, Greece, May 1997.
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Conference paper (peer-reviewed)abstract
- We investigate the possibility that gamma-ray bursts originate in a concentric spherical shell with a given average redshift and find that this is indeed compatible with the data from the third BATSE (3B) catalog. It is also shown that there is enough freedom in the choice of unknown burst properties to allow even for extremely large distances to the majority of bursts. Therefore, we speculate about an early, and very energetic, origin of bursts, and suggest that they come from phase transitions in massive objects of pure quark matter, left over from the Big Bang.
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| 3. |
- Cardona, M., et al.
(author)
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Ellipsometric investigations of piezo-optical effects
- 1998
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In: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 313-314, s. 10-17
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Journal article (peer-reviewed)abstract
- An introduction to the stress-induced birefringence of solids, with emphasis on cubic and amorphous materials, is given. Most available experimental data have been obtained in the frequency region below the electronic absorption edge: the corresponding coefficients of the stress-optical tensor are then real. Above the edge (and also in the IR region of the Reststrahlen) they become complex. Ellipsometry is an excellent tool for the investigation of complex stress-optical functions. It also yields the hydrostatic pressure induced changes in the dielectric functions. Data obtained recently for diamond and zincblende-type crystals and their theoretical interpretation are discussed.
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| 4. |
- Favre, Cécile J., et al.
(author)
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Organization of Ca2+ stores in myeloid cells: association of SERCA2b and the type-1 inositol-1,4,5-trisphosphate receptor
- 1996
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In: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 316:1, s. 137-142
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Journal article (peer-reviewed)abstract
- In this study, we have analysed the relationship between Ca2+ pumps and Ins(1,4,5)P3-sensitive Ca2+ channels in myeloid cells. To study whether sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA)-type Ca2+-ATPases are responsible for Ca2+ uptake into Ins(1,4,5)P3-sensitive Ca2+ stores, we used the three structurally unrelated inhibitors thapsigargin, 2,5-di-t-butylhydroquinone and cyclopiazonic acid. In HL-60 cells, all three compounds precluded formation of the phosphorylated intermediate of SERCA-type Ca2+-ATPases. They also decreased, in parallel, ATP-dependent Ca2+ accumulation and the amount of Ins(1,4,5)P3-releasable Ca2+. Immunoblotting with subtype-directed antibodies demonstrated that HL-60 cells contain the Ca2+ pump SERCA2 (subtype b), and the Ca2+-release-channel type-1 Ins(1,4,5)P3 receptor. In subcellular fractionation studies, SERCA2 and type-1 Ins(1,4,5)P3 receptor co-purified. Immunofluorescence studies demonstrated that both type-1 Ins(1,4,5)P3 receptor and SERCA2 were evenly distributed throughout the cell in moving neutrophils. During phagocytosis both proteins translocated to the periphagosomal space. Taken together, our results suggest that in myeloid cells (i) SERCA-type Ca2+-ATPases function as Ca2+ pumps of Ins(1,4,5)P3-sensitive Ca2+ stores, and (ii) SERCA2 and type-1 Ins(1,4,5)P3 receptor reside either in the same or two tightly associated subcellular compartments.
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| 5. |
- Kihl, Maria, et al.
(author)
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Measuring real-time performance in distributed object oriented systems
- 1999
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In: Performance and control of network systems III : 20-21 September 1999, Boston, Massachusetts. - 0819434345 ; , s. 248-258
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Conference paper (other academic/artistic)abstract
- The principles of distributed object oriented programming offer great possibilities for flexible architectures in multiple fields. In telecommunications, an architecture called Telecommunication Information Networking Architecture (TINA) has been developed using these very principles. It allows telecommunication services to be implemented using software objects that in turn can be executed in a location transparent way in a network. The location transparency offers great flexibility for service creation, but as the software must be executed somewhere in the network on nodes of finite capacity, performance problems can arise due to inefficient placement of objects causing either overloaded nodes or excessive and unneccesary inter-node communication. To ensure good performance, various measures of load control and load balancing must be taken. We discuss how to measure the performance of a distributed object oriented system and examine two load balancing algorithms that can be used in such systems. of finite capacity, performance problems can arise due to inefficient placement of objects causing either overloaded nodes or excessive and unneccesary inter-node communication. To ensure good performance, various measures of load control and load balancing must be taken. We discuss how to measure the performance of a distributed object oriented system and examine two load balancing algorithms that can be used in such systems.
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| 6. |
- Kristensson, Gerhard, et al.
(author)
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Time domain inversion techniques for electromagnetic scattering problems
- 1992
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In: Invariant imbedding and inverse problems. - 0898713056 ; , s. 1-29
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Book chapter (other academic/artistic)abstract
- This paper presents a review of and a comparison between two different methods to solve an inverse scattering problem in the time domain. The problem is that of propagation of transient electromagnetic waves in spatially inhomogeneous slabs of finite length. The permittivity and conductivity profiles are assumed to vary only with depth and the scattering problem is thus onedimensional. Several algorithms to solve the direct and inverse scattering problems for continuous and discontinuous permittivity profiles are suggested. Some of these algorithms have not been published before. The aim of this paper is to compare and review these methods. More specifically, the numerical performance of the invariant imbedding approach (layer-stripping)and the Green functions formulation (downward continuation)is compared. Some new results based upon time reversal techniques for a lossless slab are presented in an appendix.
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| 7. |
- Kröll, S., et al.
(author)
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Is rotational CARS an alternative to vibrational CARS for thermometry?
- 1990
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In: Applied Physics B-photophysics and Laser Chemistry. - 0721-7269. ; 51:1, s. 25-30
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Journal article (peer-reviewed)abstract
- Recent developments in rotational CARS thermometry and critical issues when comparing vibrational and rotational CARS thermometry are described. In particular, the development of dual broadband rotational CARS and the noise characteristics of this approach are emphasized. The difficulty with unambiguous temperature determination in vibrational CARS with unknown parameters, in particular the nonresonant background susceptibility, and the lower sensitivity of rotational CARS thermometry at flame temperatures are also discussed.
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| 8. |
- Köhler, Th., et al.
(author)
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Precision measurement of strong interaction isotope effects in antiprotonic 16O, 17O, and 18O atoms
- 1986
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 176:3-4, s. 327-333
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Journal article (peer-reviewed)abstract
- The strong-interaction effects in antiprotonic 16O, 17O, and 18O atoms were measured at the CERN antiproton facility, LEAR. The shifts ε{lunate} and the widths Γ of the 3d level were determined to be -112±20 eV (16O), -140±46 eV (17O), -195±20 eV (18O), and 495±45 eV (16O), 540±150 (17O), 640±40 eV (18O), respectively. © 1986.
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| 9. |
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| 10. |
- Linné, Agneta, Professor em. 1939-
(author)
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Moralen, barnet eller vetenskapen? : En studie av tradition och förändring i lärarutbildningen
- 1996
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Doctoral thesis (other academic/artistic)abstract
- Tradition and change in compulsory school teacher education are studied historically, using the theoretical framework of curriculum theory and theory of cultural reproduction. The concepts of classification and framing are used as analytic devices. The curriculum is analyzed by its principles of selection, organization, methods of instruction and evaluation. The objects of study are pedagogical texts and material frames; also, important actors and struggles in the field of teacher education are identified.The establishment of a State education for elementary school teachers from 1842 onwards is analyzed. Two main periods of change have been discerned - one in the 1860s and one around the turn of the century. Both these changes coincided with considerable alterations in the context of the institution of teacher training. Changes occurred in the relations between community and State networks, power relations of State bureaucracy were altered and new ideas of nature, science, the child and morality broke through. Initially, classification and framing were comparatively weak; step by step they were strengthened as State control grew more forceful. From the 1880s onwards, the dominating character of teacher education was challenged by the new professional organization created by the elementary school teachers. The strong dominance of Church and religion over education was deeply questioned in light of the newly developing sciences like empirical psychology and the natural sciences. Actors from teacher training institutes played important roles in national educational policy and in the field of teacher education. These actors have been engaged in struggles for admission to the field, for the ownership of the arena and for the power over examination - struggles concerning the distinctions of the field itself in relation to other fields.The study has demonstrated how ideas of morality, the child and science in various shapes have dominated the scene of teacher education from the mid-nineteenth to the mid-twentieth centuries.
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