| 1. |
- Sun, Chengjun, et al.
(författare)
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CRYAB-650 C>G (rs2234702) affects susceptibility to type 1 diabetes and IAA-positivity in Swedish population
- 2012
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Ingår i: Human Immunology. - : Elsevier. - 0198-8859 .- 1879-1166. ; 73:7, s. 759-766
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Single nucleotide polymorphisms (SNPs) in the promoter region of CRYAB gene have been associated with in multiple sclerosis. CRYAB gene, which encodes alpha B-crystallin (a member of small heat shock protein), was reported as a potential autoimmune target. In this study we investigated whether SNPs in the promoter region of CRYAB gene were also important in the etiology of Type 1 diabetes (T1D).METHODS: Genotyping of SNPs in the promoter region of CRYAB gene was performed in a Swedish cohort containing 444 T1D patients and 350 healthy controls. Three SNPs were included in this study: CRYAB-652 A>G (rs762550), -650 C>G (rs2234702) and -249 C > G (rs14133). Two SNPs (CRYAB-652 and -650) were not included in previous genome wide association studies.RESULTS: CRYAB-650 (rs2234702)*C allele was significantly more frequent in patients than in controls (OR = 1.48, Pc = 0.03). CRYAB-650*C allele was associated with IAA positivity (OR = 8.17, Pc < 0.0001) and IA-2A positivity (OR = 2.14, Pc = 0.005) in T1D patients. This association with IAA was amplified by high-risk HLA carrier state (OR = 10.6, P < 0.0001). No association was found between CRYAB-650 and other autoantibody positivity (GADA and ICA). CRYAB haplotypes were also associated with IAA and IA-2A positivity (highest OR = 2.07 and 2.11, respectively), these associations remain in high HLA-risk T1D patients.CONCLUSIONS: CRYAB-650 was associated with T1D in the Swedish cohort we studied. CRYAB-650*C allele might confers susceptibility to the development of T1D. CRYAB-650 was also associated with the development of IAA-positivity in T1D patients, especially in those carrying T1D high-risk HLA haplotypes.
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| 2. |
- Mundy, Lee G., et al.
(författare)
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High-resolution images of the Orion molecular ridge in the CS J = 2-1 transition
- 1988
-
Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 325:1, s. 382-388
-
Tidskriftsartikel (refereegranskat)abstract
- The authors have constructed 7arcsec.5 resolution images of the CS J = 2-1 emission from a 3arcmin.5 section of the Orion molecular ridge using a maximum entropy algorithm to combine Owens Valley Millimeter-Wave Interferometer and Onsala Space Observatory 20 m data. The resulting images include all of the flux and have positional accuracy of 1arcsec-2arcsec on the small-scale features. The observed section of the ridge includes four condensations. The condensations have dimensions from 0.03 to 0.11 pc and virial massses from 30 to 80 M_sun;. Approximately 70% of the total mass within the 3arcmin region is contained in these condensations.
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| 3. |
- Pettersson, Håkan, et al.
(författare)
-
Optically induced charge storage and current generation in InAs quantum dots
- 2002
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 65:7, s. 0733041-0733044
-
Tidskriftsartikel (refereegranskat)abstract
- We report on optically induced charge storage effects and current generation in self-assembled InAs quantum dots embedded in an InP matrix. Illumination with photons of energy higher than about 0.86 eV efficiently loads the dots with a maximum of about 1 hole/dot. The spectral response at lower photon energy is strongly enhanced at elevated temperatures. We present a detailed balance model for the dots and discuss the thermally assisted optical excitation processes pertinent to hole accumulation. We also show that these processes make the dots act as nanometer-scaled temperature-dependent current generators.
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| 4. |
- Alberdi, A., et al.
(författare)
-
The high-frequency compact radio structure of the peculiar quasar 4C 39.25
- 1997
-
Ingår i: Astronomy and Astrophysics. - : Springer-Verlag. - 0004-6361 .- 1432-0746. ; 327:2, s. 513-521
-
Tidskriftsartikel (refereegranskat)abstract
- We present new high angular resolution images of the compact non-thermal radio source 4C 39.25 obtained from VLBI observations at λ1.3cm, λ7mm, and λ3mm wavelengths. These maps and Gaussian model-fits show that the milli-arcsecond to sub-milliarcsecond structure of 4C 39.25 consists of a complex bent core-jet structure with embedded moving and stationary VLBI components. Facilitated by the small observing beams and high angular resolutions obtained at mm-wavelengths, we measured the relative positions of the jet components with an accuracy of a few hundred micro-arcseconds. This allows the detailed followup of the ongoing merging process of a westward superluminally moving component (b_) with a stationary component a_, located at ~2.9 mas east of the putative core d_. In contrast to the other components of the structure with steeper spectra, the westernmost component d_ exhibits an inverted spectrum peaking between λ7mm and λ3mm, thus further supporting its identification as the VLBI core, self-absorbed at longer wavelengths. From two VLBI maps obtained nearly simultaneously at λ7mm and λ1.3cm, we made the first spectral index map of 4C 39.25 in this wavelength regime. The main characteristics of the spectral index distribution of the jet are pronounced changes of the spectral index between orientations parallel and transverse to the jet axis. Near the merging components a_ and b_ the spectral index steepens with increasing separation from d_. However, in the bridge of emission c_, which connects d_ with a_ and b_, the spectral index gradient has a direction transverse to the jet axis, suggesting a frequency dependent jet curvature and edge-brightening. A brief discussion of this behaviour within current jet models is presented.
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| 5. |
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| 6. |
- Bååth, Lars B.
(författare)
-
Analys av avgaser med mikrovågspektroskopi
- 2004
-
Rapport (refereegranskat)abstract
- Inom projektet har hittills genomförts följande aktiviteter:Inhämtat teoretiska kunskaper inom området mikrovågsteknikGenomfört studier avseende vilka molekyler som är av intresse för stål- och metallindustrin att mäta på.Kontrollerat mot JPL databas samt NBS om dessa molekyler finns definierade i mikrovågsområdet av det elektromagnetiska spektret och då på vilka frekvenser.Designat och tillverkat en sensor, bestående av antenner, mixer samt LO, som klarar av att mäta vid de relevanta molekylära frekvenserna.Testat och utvärderat sensortekniken på laboratorienivå avseende signalkarak- täristik.Genomfört pilotförsök på MEFOS: i. Höga gastemperaturer; ii. Olika gaskoncentrationerGenomförtverksförsök: i. LKAB, Rotary Kiln; ii. Boliden Mineral, KopparkonverterUtvärderat försöksdata
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| 7. |
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| 8. |
- Bååth, Lars B., et al.
(författare)
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Imaging with Interferometers
- 1998
-
Ingår i: Proceedings SSAB Symposium on Image Analysis. ; , s. 4-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A scanning device based on changes in the reflections of an electromagnetic wave for use on wood the image can be calculated.
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| 9. |
- Bååth, Lars B., 1948-
(författare)
-
Method and device for contactless level and interface detection
- 2006
-
Patent (populärvet., debatt m.m.)abstract
- Method and apparatus for determining the thickness of material layers of a container-held substance comprising a first material disposed in an upper layer and a second material disposed in a lower layer, by transmitting a radio signal through the substance towards a container portion; receiving reflected signals from a surface of the upper layer, a surface of the second layer, and the container portion; varying the frequency of the transmitted signal to determine phase displacement between transmitted and reflected signals; determining optical distances to the surfaces and the container portion, dependent on the phase displacements; determining the thickness of one of said layers dependent on phase displacement through and index of refraction of that layer; and determining the thickness of the other layer dependent on the thickness of said one of said layers.
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| 10. |
- Bååth, Lars B., 1948-
(författare)
-
Method for analysing a substance in a container
- 2006
-
Patent (populärvet., debatt m.m.)abstract
- Method and apparatus for analyzing a substance in a container, the method comprising the steps of: disposing antenna means (3) at a predetermined geometrical distance (L) from a container portion (13); transmitting a signal from said antenna means through a surface portion (12) of the substance towards said container portion; receiving a first reflected signal in said antenna means from said container portion; determining a geometrical distance (L1) from the surface portion to the container portion; varying the frequency of the transmitted signal to determine a first phase displacement between the transmitted signal and the first reflected signal; determining an optical distance from the surface portion to the container portion based on the first phase displacement; and determining the index of refraction (nt) of said substance based on the optical and geometrical from the surface portion to the container portion.
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| 11. |
- Bååth, Lars B., 1948-
(författare)
-
mm VLBI
- 1993
-
Ingår i: VLBI Technology – Progress and Future Observational Possibilities. - Tokyo : Terra Scientific Publishing Company. ; , s. 70-74
-
Bokkapitel (refereegranskat)abstract
- Very long Baseline Interferometry (VLBI) has now made its break-through into the mm wavelength regime. A global VLBI array has produced maps of radio sources at 3 mm since 1988 and development is under way to improve the sensitivity for VLBI also at 1 mm. This contribution discusses the present state of mm VLBI and the future developments.
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| 12. |
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| 13. |
- Bååth, Lars B.
(författare)
-
Radio Wave Interferometer Measurements of Slag Depth
- 2003
-
Ingår i: Iron & Steel society international technology conference and exposition 2003. - : Iron and Steel Society. ; , s. 875-882
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- During the past decade software to control metallurgical processes has improved to require new physical sensors for feedback. We present a non-invasive interferometric technique to simultaneously measure multiple levels in dynamic metallurgical processes, e.g. the foam-, slag-, emulsion-, and steel-layers in furnaces. The measurements are continuous and on-line during production.
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| 14. |
- Bååth, Lars B., et al.
(författare)
-
Surface topography with PDI holography
- 2008
-
Ingår i: Proceedings of the XII. International Colloquium on Surfaces. - Aachen : Shaker Verlag. - 9783832269128 ; , s. 10-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents topographic measurements of metal surface with Point Diffraction Interferometer (PDI) technique. Interferogram of a surface is created and recorded with different phase offsets. These are then combined to create a phase offset map of the surface. We demonstrate the use with the presentation of our first surface topographic map
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| 15. |
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| 16. |
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| 17. |
- Chu, H.S., et al.
(författare)
-
Discovery of Helical Magnetic Fields in AGN and CME and Ejection of Large Scale Magnetic Fields from AGN
- 2003
-
Ingår i: Symposium - International astronomical union. - : International Astronomical Union. - 0074-1809. ; 214, s. 303-310
-
Tidskriftsartikel (refereegranskat)abstract
- Magnetic Fields are the crucial and most important ingredient involved in the processes of various violent activities in Active Galactic Nuclei and other celestial bodies. The generally accepted 2-sided symmetric-jets model of active galactic nuclei (AGN) does not include the magnetic fields. We present here the first direct detection of helical magnetic field in AGN, and the first direct detection of ejection of large scale magnetic fields from AGN. (CME) 2. The annular (helical) magnetic field is responsible for the collimation of the jet (through Pinch Effect) and may be of crucial importance for extraction of black hole rotational energy. 3. The CMEs are responsible for sporadic ejection of jet components in AGN, while the general accepted 2-sided jets pertain to the quiescent Jets. 4.Observations show that the CME with Asymmetric Jets can explain many phenomena and much of the morphological diversities in AGN.
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| 18. |
- Chu, H.S., et al.
(författare)
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VLBI observations of the puzzling BL Lacertae object 0235+164
- 1996
-
Ingår i: Astronomy and Astrophysics. - : Springer. - 0004-6361 .- 1432-0746. ; 307:1, s. 15-20
-
Tidskriftsartikel (refereegranskat)abstract
- For over 20 years, many models have been proposed to explain the variability of AO0235+164. Among them, the most favorable has been micro-lensing. We have made a series of VLBI observations on this source in order to better understand its nature. The resultant maps indicate dramatic changes in the position angle of the jet between observations as well as a correlation between the intensity of the VLBI core and flux outbursts which occurred between the observing sessions. These characteristics, in conjunction with other arguments, suggest that the source variability is intrinsic, i.e. microlensing is of minor importance. We suggest two models: 1) a model in which the jet starts at a very small angle to the line of sight and then curves away to become about 6deg at about 1 mas from the core; and 2) a CME (Coronal Mass Ejection) model that also may explain the violent variability in intensity, polarization position angle, and jet direction in AO0235+164.
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| 19. |
- Davidenko, N. A., et al.
(författare)
-
Electro-optical effect in films of azobenzene polycomplexes with cobalt
- 2008
-
Ingår i: Journal of Applied Physics. - College Park, MD : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 103:9, s. Article number 094323-
-
Tidskriftsartikel (refereegranskat)abstract
- Polymeric films containing azobenzene fragments with donor and acceptor groups were produced as well as films of polycomplexes of these fragments with cobalt. Absorption spectra of these films before and during application of an external electric field were investigated. Electro-optical properties of the films are conditioned by spatial reorientation of dipole moments of azobenzene groups induced by polarized light in an external electric field. Increase in dipole moments of azobenzene groups reduces the influence of cobalt ions on the electro-optical properties of the polycomplex films. In the proposed phenomenological model, the electro-optical effect is explained by effect of induced forces upon azobenzene isomers and metallic ions.
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| 20. |
- Davidenko, N.A., et al.
(författare)
-
Thermal influence on passing of polarized light through the SnO2 : In2O3 layers
- 2006
-
Ingår i: Journal of Applied Physics. - Lancaster : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 100:2, s. 023111-1-023111-3
-
Tidskriftsartikel (refereegranskat)abstract
- Thermal dependent changes of light depolarization degree were observed in the SnO2:In2O3 (ITO) layers deposited onto the flat glass substrates which are used usually as electrodes for optoelectronic devices. The observed effect is reversible. It can be attributed to the changes of nanostructure geometry in the bulk of the ITO layer as well as on its surface. Such geometric changes involve dispersion of polarized light. The investigated effect should be taken into consideration when developing optoelectronic devices because it can provoke distortion of the optical information field.
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| 21. |
- Fhager, Andreas, et al.
(författare)
-
Microwave Imaging for Mammography using an Iterative Time-Domain Reconstruction Algorithm; Initial Experiments
- 2005
-
Ingår i: Proceedings of the 16th International Zurich Symposium on Electromagnetic Compatibility; Topical Meetings. - Zürich : Laboratory for Electromagnetic Fields and Microwave Electronics, Swiss Federal Institute of Technology. ; , s. 65-70
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Using the microwave imaging technique for mammographic imaging is an interesting application and a growing research field. Compared to X-ray mammography there is potentially a significant benefit in using microwaves in the diagnosis of breast cancer tumours due to the high contrast in the dielectric properties between tumour and surrounding tissue.In this paper a tomographic microwave imaging ex- periment using transient time domain field data for the reconstruction process. A 2D iterative gradient based al- gorithm based on the FDTD-method (Finite Difference Time Domain-method), is used for the image reconstruction. The reconstructions have been performed using air as the background medium. To simulate more tissue like conditions the antennas have also been immersed in water and different objects immersed in the water have been imaged. Two different antenna models in the computations have also been tested. The results are promising and encourages further research on this method
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| 22. |
- Hashemzadeh, Parham, et al.
(författare)
-
Imaging of metal prostheses in the human body : experiments and simulations
- 2005
-
Ingår i: Proc. RVK 05, Radiovetenskap och kommunikation, Linköping, Sweden, June 14-16 2005. - : Svenska Nationalkommittén för radiovetenskap (SNRV). ; , s. 67-70
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper with present the experimental results of imaging a 12mm copper rod immersed in water with a relative permittivity of ε = 78 , σ = 0.2. A copper rod is a simpler object to analyze for these first series of investigations than a hip prostesis. One should note that it has a relative permeability μ = μ0. The prosteses is also manufactured using titanium and it posseses a similiar permeability to that of copper. The setup used is very similiar to that proposed for the detection of breast cancer tumors [1],[2].The metalic rod is immeresed in water and is surrounded by an array of transceivers. The multi static data matrix is recorded as a function of frequency on the boundary of the medium under test. The multi static data matrix is a square complex symmetrix matrix. The elements consist of the received relative amplitude and phase between each sensor element as a function of frequency. A vector network analyzer and a switching matrix is used as the transceiver module. The mulitstatic data matrix is fourier transformed to time domain in order to be used in the FDTD based algorithm. The imaging algorithm used is similiar but a modified version to that proposed by Tanaka, Takenaka, He[3] and Gustafsson,He [4].The results of these first attempts to image metalic object are very promising and one can potentially use the proposed setup in various fields of medical imaging.
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| 23. |
- Kaestner, Anders P., et al.
(författare)
-
Microwave polarimetry based wood scanning
- 2000
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Ingår i: Proceedings of the 12th International Symposium on Nondestructive Testing of Wood. - Sopron : University of Western Hungary. - 9637180885 ; , s. 8-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We describe a method to detect knots and faults in wood logs based on microwave measurements and the depolarising properties of wood. The depolarisation is an effect of the anisotropy in the dielectric properties of wood, which is caused by the fibre structure. The measurements are made in the frequency domain where a discrete reflec-tion spectrum is sampled. By transforming the frequency spectrum into the time domain the spatial distribution of the reflections appear. The wave is transmitted in a pure linear polarisation, tilted to 45° For each discrete frequency all available information is measured for the reflected wave and therefore it is possible to calculate the complex polarisation ratio and the state of polarisation which are the quantities containing the most visible information. The measurements are one dimensional and by combining measurements from different directions we create tomographic slice images of the inner structure of a log. Our measurements has showed the possibility to follow the extension of knots in a log using only a iso-surface visualisation. The used equipment is working at low intensity and is therefore virtually harm-less to human beings, furthermore it is portable and can be operated by one single person.
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| 24. |
- Kaestner, Anders P., et al.
(författare)
-
Microwave polarimetry tomography of wood
- 2005
-
Ingår i: IEEE Sensors Journal. - New York : IEEE Sensors Council. - 1530-437X .- 1558-1748. ; 5:2, s. 209-215
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present a new microwave-based method to make images of fiber structure, e.g., to locate knots in wood. Evaluation of Maxwell's equations for an electromagnetic wave propagating in an anisotropic media (wood) shows that the polarization of the wave depends on the local fiber orientation in the sample. Experiments support the theoretical evaluation showing that knots can be followed in images of polarimetric parameters, reconstructed from multiple monostatic measurements. The equipment works at low intensity and is, therefore, virtually harmless to human beings; furthermore, it can be made portable and be operated by a single person.
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| 25. |
- Malmberg, Donald, et al.
(författare)
-
Preliminary microwave measurements on liquid stags
- 2005
-
Ingår i: Ironmaking & steelmaking. - London : Maney Publishing. - 0301-9233 .- 1743-2812. ; 32:1, s. 61-67
-
Tidskriftsartikel (refereegranskat)abstract
- Microwave technology has for decades been a tool for astronomers in their work to map and understand the complexities of the universe in terms of composition and extent but it is also used at laboratory scale by spectroscopists to examine the properties of atomic and molecular compounds. This paper discusses the use of microwave technology for the investigation of liquid slag structures. Preliminary results indicate that alteration of slag composition could be correlated to the measured microwave refractive index. Investigations have been performed on Al2 O3 -CaO-SiO2.
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| 26. |
- Malmberg, Donald, et al.
(författare)
-
Slag level detection in EAFs using microwave technology
- 1999
-
Ingår i: Scandinavian journal of metallurgy. - : Blackwell Publishing Ltd.. - 0371-0459 .- 1600-0692. ; 28:6, s. 266-276
-
Tidskriftsartikel (refereegranskat)abstract
- Within the metallurgical industry as well as the underground mine industry, there is a need for on-line level detection in the different production processes and their material feeding systems. Microwave technology is a versatile, non-invasive measurement technique, which has a number of advantages compared with penetrating probes, laser and radar technology, and echo sound technique. In its extension, it could also be used for qualitative and quantitative analysis of waste gases due to the presence of specific molecules. This contribution describes the introduction of microwave technology in different metallurgical as well as underground mine production processes with the emphasis on EAF's.
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| 27. |
- Matveenko, L. I., et al.
(författare)
-
The injector and variability of the quasar 3C 345
- 1996
-
Ingår i: Astronomy letters. - Moscow : MAIK Nauka/Interperiodica. - 1063-7737 .- 1562-6873. ; 22:1, s. 14-23
-
Tidskriftsartikel (refereegranskat)abstract
- The VLBI technique is used to study the fine structure of the quasar 3C 345 at = 49 cm. It is shown that the low-frequency radio emission from the core is feeble, whereas the bright compact component corresponds to the jet region adjacent to the core, rather than to the core itself. This region is ~6.4 mas in size, and its brightness temperature, Tb near equal 0.6 1012 K, does not go beyond the Compton limit. The core itself is an injector of relativistic particles surrounded by a wall of thermal plasma. Between 1983.9 and 1990.8, the radio flux density and angular size of the compact component increased by a factor of about 2, while its brightness temperature did not change markedly. During this period, the emission at millimeter wavelengths was reduced about twofold; the UV emission also decreased. The low-frequency variability is shown to be a result of variations in the transparency of the wall of a cocoon—the thermal plasma surrounding the jet. The electron density in the cocoon wall near the bright compact component is Ne near equal 105 cm3 and rises toward the core as ~ r 2. The polarized emission of the quasar originates mainly from the same region, where compact sources are seen athigh frequencies. Its rotation measure is RM near equal 29 rad m–2 and increases toward the core as ~ r 3, reaching 8 104 rad m–2. In the vicinity of the core, the longitudinal component of the magnetic field is ~0.1 mG.
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| 28. |
- Mundy, Lee G., et al.
(författare)
-
Protostellar Condensations within the Orion Ridge
- 1986
-
Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 304:2, s. L51-L55
-
Tidskriftsartikel (refereegranskat)abstract
- Aperture synthesis observations of the CS J = 2 to 1 line and 95 GHz continuum emission from a 2 arcmin x 3 arcmin region around IRc2 in the OMC-1 molecular cloud have been obtained at 7.5 arcsec resolution with the Owens Valley Radio Observatory millimeter interferometer. These observations reveal four distinct condensations with the OMC-1 molecular ridge. The condensations lie along the edge of the bright central part of the H II region, M 42, suggesting that they may have been formed as a result of shock compression driven by the H II region. Their masses and densities, M about 50 solar masses and n about 10 to the 6th - 10 to the 7th/cu cm, suggest that the condensations will undergo further massive star formation on a short time scale (about 20,000 yr).
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| 29. |
- Nilsson, Emil, 1972-, et al.
(författare)
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Blast Furnace Burden Topography
- 2007
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Ingår i: Proceedings Conference on Mets & Props, 2007. ; , s. 1-
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Within the global steel-and metal industry there is a growing need for new sensor systems to measure and control the industrial process. New technologies for new sensors are continuously being developed for an ever growing market. The growth in the steel making industry is based on ore and Blast Furnaces therefore play an increasingly important role for the production of hot liquid iron and steel. We present a new interferometer micro wave system to makethree dimensional topographic maps of the blast furnace burden surface. The Blast Furnace process is one of the oldest industrial processes. The furnace is tall and round. Layers of Coke ands iron ore are successively laid, and air, pre-heated to 1200 °C, as fuel to the process. The coke and iron layers become semi-liquid and then liquid in the cohesive zone. The carbon from the coke reacts with the oxygen in the ore (which is Fe2O3or Fe3O4) and form CO and CO2which goes off as off-gas. The iron, now mixed with some amount of carbon, is tapped in liquid form from the bottom. This is then taken to a converter, where oxygen is added to remove the carbon to form the final product of liquid steel.
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| 30. |
- Otarola, A., et al.
(författare)
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Site Survey for a Large Southern Array
- 1996
-
Ingår i: Science with large millimetre arrays. - Berlin : Springer. - 3540615822 ; , s. 358-364
-
Bokkapitel (refereegranskat)
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| 31. |
- Pettersson, Håkan, 1962-, et al.
(författare)
-
Case study of an InAs quantum dot memory : Optical storing and deletion of charge
- 2001
-
Ingår i: Applied Physics Letters. - New York : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 79:1, s. 78-80
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied self-assembled InAs quantum dots embedded in an InP matrix using photocapacitance and photocurrent spectroscopy. These dots are potentially promising for memories due to the large confinement energy for holes. In this work we have realized simple quantum dot memory by placing the dots in the space–charge region of a Schottky junction. Our measurements reveal that a maximum of about one hole can be stored per dot. We also find that illumination for an extended period deletes the stored charge. We show that these limitations do not reflect the intrinsic properties of the dots, but rather the sample structure in combination with deep traps present in the sample.
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| 32. |
- Pikwer, Andreas, et al.
(författare)
-
Routine chest X-ray is not required after a low-risk central venous cannulation.
- 2009
-
Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 53, s. 1145-1152
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Knowledge of the radiographic catheter tip position after central venous cannulation is normally not required for short-term catheter use. Detection of a possible iatrogenic pneumothorax may nevertheless justify routine post-procedure chest X-ray. Our aim was to design a clinical decision rule to select patients for radiographic evaluation after central venous cannulation. Methods: A total of 2230 catheterizations performed using external jugular, internal jugular or subclavian venous approaches during a 4-year period were included consecutively. Information on patient data and corresponding procedures was recorded prospectively. A post-procedure chest X-ray was obtained after each cannulation. Results: Thirteen cases (0.58%) of cannulation-associated pneumothorax were identified. The risk of pneumothorax after a technically difficult (1.8%) or subclavian (1.6%) cannulation was significantly higher than after cannulation not considered as difficult (0.37%) or performed using other routes (0.33%). Clinical signs of pneumothorax within 8 h of cannulation were found in all seven patients with pneumothorax requiring specific treatment. A new clinical decision rule for radiographic evaluation after central venous cannulation based on the results of the present study shows that 48% of the post-procedure chest X-rays performed in our patients were clinically redundant. Conclusion: Clinical symptoms were reported in all patients with pneumothorax requiring specific treatment. Approximately half of the post-procedure chest X-ray controls could be avoided using the proposed clinical decision rule to select patients for radiographic evaluation after central venous cannulation. A large prospective multi-centre study should be carried out to further evaluate this decision rule.
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| 33. |
- Pikwer, Andreas, et al.
(författare)
-
The incidence and risk of central venous catheter malpositioning: a prospective cohort study in 1619 patients.
- 2008
-
Ingår i: Anaesthesia and Intensive Care. - 0310-057X. ; 36:1, s. 30-37
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Tidskriftsartikel (refereegranskat)abstract
- Central venous catheters are used in various hospital wards. An anterior-posterior chest X-ray is usually obtained soon after cannulation to assess the location of the catheter tip. This prospective clinical study was designed to determine the radiographic catheter tip position after central venous cannulation by various routes, to identify clinical problems possibly associated with the use of malpositioned catheters and to make a cost-benefit analysis of routine chest X-ray with respect to catheter malposition. A total 1619 central venous cannulations were recorded during a three-year period with respect to patient data, information about the cannulation procedures, the radiographic catheter positions and complications during clinical use. The total incidence of radiographic catheter tip malposition, defined as extrathoracic or ventricular positioning, was 3.3% (confidence interval 25 to 4.3%). Cannulation by the right subclavian vein was associated with the highest risk of malposition, 9.1%, compared with 1.4% by the right internal jugular vein. Six of the 53 malpositioned catheters were removed or adjusted. No case of malposition was associated with vascular perforation, local venous thrombosis or cerebral symptoms. We conclude that the radiographic incidence of central venous catheter malpositioning is low and that clinical use of malpositioned catheters is associated with few complications. However, determination of the catheter position by chest X-ray should be considered when mechanical complications cannot be excluded, aspiration of venous blood is not possible, or the catheter is intended for central venous pressure monitoring, high flow use or infusion of local irritant drugs.
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| 34. |
- Rantakyrö, F.T., et al.
(författare)
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50 μas resolution VLBI images of AGN’s at λ3 mm
- 1998
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Ingår i: Astronomy and Astrophysics. - Berlin : Springer-Verlag. - 0004-6361 .- 1432-0746. ; 131, s. 451-467
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Tidskriftsartikel (refereegranskat)abstract
- We present 15 images from the global mm-VLBI sessions in 1990 April at 100 GHz and 1993 April at 86 GHz. These observations probe the central engines of the 16 observed AGN's with up to 50 mu as resolution. Among other sources previously observed with lambda 3 mm VLBI we present the first lambda 3 mm maps of 0735+178, 0748+126, 1055+018, 2145+067, and CTA102, in total we have been able to image 13 out of the 16 observed sources. 6 out of the 13 imaged sources observed exhibit curvature and rapid structural changes, although the low dynamic range in two thirds of the maps limits the detection of weak features. Most of the sources have unresolved cores even at this high resolution. There is substantial evidence that the observed sources can be grouped into two general groups: A misaligned population with parsec scale jets in the form of low pitch helices and an aligned population with straight jets with small changes in PA due to intrinsic bends.
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| 35. |
- Rantakyrö, Fredrik T., et al.
(författare)
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Multiband VLBI observations of CTA 102
- 1996
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 310:1, s. 66-74
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Tidskriftsartikel (refereegranskat)abstract
- The source CTA102, known to exhibit low frequency variability, has been observed at six epochs (three at λ32cm, two at λ18cm, and one at λ1.3cm) with intercontinental VLBI arrays. On the basis of the changes observed in the structure, we believe that the flux density variations at these wavelengths are due to intrinsic processes and not due to interstellar scintillation. This source exhibits behaviour suggestive of being expanding with a very high apparent transverse velocity.
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| 36. |
- Rantakyrö, F.T., et al.
(författare)
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Multifrequency interferometer and radio continuum monitoring observations of CTA 102
- 2003
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Ingår i: Astronomy and Astrophysics. - Berlin : Springer. - 0004-6361 .- 1432-0746. ; 42:5, s. 473-485
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Tidskriftsartikel (refereegranskat)abstract
- This paper represents the work of several years of observation of CTA 102 with both single dish telescopes andinterferometric arrays, covering wavelengths from 1.2 cm to 1.3 mm. The resolution of the maps covers an order of magnitudefrom 0.5 mas to 50 μas. The images presented demonstrate the rapid structural changes in this source. These rapid structuralchanges correlates with the outbursts seen in the total flux, turnover frequency and in the spectral index. We have calculated theBrightness Temperatures of the components (TB ) directly from the determined component sizes and also using the logarithmicvariability amplitudes and timescales to calculate the TB s. Both the methods yielded measurements of source frame T Bs nohigher than∼a few × 1012K. We find that the observed average proper motion is0.4 0.07 mas/yr, which corresponds to anapparent transverse velocity of 11± 2 c.
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| 37. |
- Rantakyrö, F. T., et al.
(författare)
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Structural Changes in CTA102
- 1996
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Ingår i: Extragalactic radio sources. - Boston : Kluwer. - 079234121X ; , s. 39-40
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 38. |
- Ruusla, Jari, et al.
(författare)
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Possibilities to use new measurements to control LD-KG-converter
- 2006
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Ingår i: Proceedings of the 5th European Oxygen Steelmaking Conference. - Düsseldorf : Verl. Stahleisen. - 9783514007277 ; , s. 8-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Measuring from the converter is demanding. On the project financed by Rautaruukki Oyj and TEKES (the Technology Agency of Finland) the aim of the project was to develop the control of the converter during the blow by improving the usability of current measurements and by testing new measurements. Splashing measurement based on image analysis was found out to be good and it was taken into use. Also test experiment with Agellis-measurement showed promising results to measure levels within the converter.
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| 39. |
- Su, Bu-Mei, et al.
(författare)
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Sub-milliarcsecond radio structure of three quasars
- 2001
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Ingår i: Chinese Astronomy and Astrophysics. - : Elsevier. - 0275-1062 .- 1879-128X. ; 25:1, s. 23-28
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Tidskriftsartikel (refereegranskat)abstract
- The quasars, 0420-014, 0748+126 and 2251+158 (3C 454.3), have been observed at 1.3 cm with a global VLBI network. We have obtained the hybrid maps of the quasars at sub-milliarcsecond resolution. The brightness distribution is revealed in their nuclear regions. The observed data are fitted with a small number of Gaussian components. 2251+158 shows a core-jet structure, and its nuclear region is elongated in the direction PA= -130o. The jet is curved. Its observations at the epoch 1992.9 show it to be in the course of a large burst, accompanied by several smaller ones. The strongest component has a flux of ~ 4.11 Jy (67% of the total detected flux), mostly from an area of 0.16 x 0.01 mas. Doppler boosting is probably responsible for raising the brightness temperature up to 2.6 x 1012 K.
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| 40. |
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| 41. |
- Tateyama, Claudio E., et al.
(författare)
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Global 3- and 7-mm VLBI Observations of OJ 287
- 1996
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Ingår i: Nippon Tenmon Gakkai obun kenkyu hokoku. - Japan : Astronomical Society of Japan. - 0004-6264. ; 48:1, s. 37-44
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Tidskriftsartikel (refereegranskat)abstract
- We present new results from global VLBI observations of the highly active blazar OJ287 at 7 and 3 mm wavelengths. We show the first map of the mas to sub-mas structure of OJ287 at 43 GHz and discuss this image in the context with models of the source structure seen at 100 GHz.
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| 42. |
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| 43. |
- Zhang, Fu-Jung, et al.
(författare)
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Viewing angles in some selected BL Lac objects
- 1996
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Ingår i: Astrophysics and Space Science. - : Springer. - 0004-640X .- 1572-946X. ; 235:2, s. 195-205
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Tidskriftsartikel (refereegranskat)abstract
- A selected subset of BL Lac objects were monitored with VLBI techniques at multifrequencies. Apparent superlumJnal motion and X-rays were detected in all of the monitored sources. From the observational data, kinematic parameters, geometric parameters and beaming effects for the 'core' of the selected BL Lac objects have been estimated. Our results indicate that some BL Lacs have large Lorentz factors and small viewing angles; relativistic beaming effects are strongly present in these sources. On the other hand, some BL Lacs have small Lorentz thctors; their viewing angles are quite large. It does not seem possible to avoid the fact that some BL Lac objects are not oriented particularly close to the line of sight. It conflicts with the basic assumption of the accepted theories for explaining the characteristics of BL Lac objects at present. Also, it seems that the BL Lac objects in the class I of the Burdige and Hewitt's classification have larger viewing angles than those int he class II. The whole BL Lac classification could be a misnomer: the sources classified as 'BL Lac objects' are a mixture of physically different populations with different parent objects.
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