| 1. |
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| 2. |
- Falci, S, et al.
(författare)
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Obliteration of a posttraumatic spinal cord cyst with solid human embryonic spinal cord grafts : first clinical attempt.
- 1997
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Ingår i: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 14, s. 875-
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Tidskriftsartikel (refereegranskat)abstract
- Cystic lesions of the spinal cord (syringomyelia) may occur after spinal cord injury. Posttraumatic syringomyelia may result in a myelopathy causing symptoms of sensory and motor loss, as well as worsening spasticity, pain, hyperhidrosis, and autonomic dysreflexia. Shunting of the cyst cavity along with untethering of the scarred spinal cord is widely accepted as the treatment of choice. However, the long-term stabilization of the progressive myelopathy caused by a posttraumatic cyst is suboptimal because of arachnoidal rescarring, shunt tube blockage, and cyst reexpansion. A new neurosurgical strategy to overcome the complication of cyst reexpansion was designed. Experimental studies have shown the successful use of embryonic spinal cord grafts, including human grafts, to obliterate induced spinal cord cavities in rats. The authors report the first use of solid human embryonic spinal cord grafts to successfully obliterate 6 cm of a large cyst cavity in a patient becoming myelopathic from a posttraumatic cyst. The grafts are well visualized by MRI to the 7-month postoperative follow-up and cyst obliteration is seen in the region where the grafts were placed.
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| 3. |
- Engquist, M., et al.
(författare)
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A 5-to 8-year randomized study on the treatment of cervical radiculopathy: anterior cervical decompression and fusion plus physiotherapy versus physiotherapy alone
- 2017
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Ingår i: Journal of Neurosurgery-Spine. - : Journal of Neurosurgery Publishing Group (JNSPG). - 1547-5654. ; 26:1, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE The aim of this study was to evaluate the 5- to 8-year outcome of anterior cervical decompression and fusion (ACDF) combined with a structured physiotherapy program as compared with that following the same physiotherapy program alone in patients with cervical radiculopathy. No previous prospective randomized studies with a follow-up of more than 2 years have compared outcomes of surgical versus nonsurgical intervention for cervical radiculopathy. METHODS Fifty-nine patients were randomized to ACDF surgery with postoperative physiotherapy (30 patients) or to structured physiotherapy alone (29 patients). The physiotherapy program included general and specific exercises as well as pain coping strategies. Outcome measures included neck disability (Neck Disability Index [NDI]), neck and arm pain intensity (visual analog scale [VAS]), health state (EQ-5D questionnaire), and a patient global assessment. Patients were followed up for 5-8 years. RESULTS After 5-8 years, the NDI was reduced by a mean score% of 21 (95% CI 14-28) in the surgical group and 11% (95% CI 4%-18%) in the nonsurgical group (p = 0.03). Neck pain was reduced by a mean score of 39 mm (95% CI 26-53 mm) compared with 19 mm (95% CI 7-30 mm; p = 0.01), and arm pain was reduced by a mean score of 33 mm (95% CI 18-49 mm) compared with 19 mm (95% CI 7-32 mm; p = 0.1), respectively. The EQ-5D had a mean respective increase of 0.29 (95% CI 0.13-0.45) compared with 0.14 (95% CI 0.01-0.27; p = 0.12). Ninety-three percent of patients in the surgical group rated their symptoms as "better" or "much better" compared with 62% in the nonsurgical group (p = 0.005). Both treatment groups experienced significant improvement over baseline for all outcome measures. CONCLUSIONS In this prospective randomized study of 5- to 8-year outcomes of surgical versus nonsurgical treatment in patients with cervical radiculopathy, ACDF combined with physiotherapy reduced neck disability and neck pain more effectively than physiotherapy alone. Self-rating by patients as regards treatment outcome was also superior in the surgery group. No significant differences were seen between the 2 patient groups as regards arm pain and health outcome.
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| 4. |
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| 5. |
- Shamirzaev, T S, et al.
(författare)
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Atomic and energy structure of InAs/AlAs quantum dots
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 78:8
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Tidskriftsartikel (refereegranskat)abstract
- The atomic structure and energy spectrum of InAs quantum dots (QDs) in an AlAs matrix have been experimentally studied by transmission electron microscopy (TEM) and steady-state photoluminescence (PL) combined with computational work. The degree of intermixing of InAs and AlAs has been investigated by means of TEM and PL compared with theoretical predictions and found to increase with increasing growth temperature and growth interruption. The band alignment in the QDs is shown to be of type I with the lowest conduction-band states at the direct Γ or at the indirect XXY minima of the QD conduction band, depending on the QD's size and composition. © 2008 The American Physical Society.
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| 6. |
- Shubina, Tatiana, et al.
(författare)
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Optical properties of GaN/AlGaN quantum wells with inversion domains
- 2003
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Ingår i: Physica status solidi. A, Applied research. - : Wiley. - 0031-8965 .- 1521-396X. ; 195:3, s. 537-542
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Tidskriftsartikel (refereegranskat)abstract
- Two-band photoluminescence (PL) and respective absorption and reflection features are observed in GaN/AlGaN MBE-grown quantum well (QW) structures of dominant N polarity with inversion domains (IDs). The PL bands are related to transitions in the regions of different polarity, characterized by different strain and electric fields. A micro-PL study reveals sharp and narrow (1.5-2.5 meV) PL lines placed between the bands, which are tentatively attributed to recombination at localization sites associated with intersections of the QWs with the domains. Additionally, we demonstrate that the ID formation decreases the overall strength of the intrinsic electric fields in the QW structures.
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| 7. |
- Toropov, A.A., et al.
(författare)
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Temperature-dependent exciton polariton photoluminescence in ZnO films
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:16, s. 165205-
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Tidskriftsartikel (refereegranskat)abstract
- The polarized photoluminescence (PL) in a (0001) oriented ZnO epitaxial film is studied in the temperature range 4.5-250 K. We report the evidence of exciton polariton emission between 50 and 130 K. In this range the PL of mixed polariton modes is detected in the geometry of an extraordinary beam, realized by the use of a large-aperture microobjective collecting light from the cleaved sample edge at different angles with respect to the. c axis. The elevated temperatures facilitate the polariton emission due to the thermal population of both A and B exciton branches and the enhanced polariton scattering into the photonlike mixed modes.
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| 8. |
- Dupertuis, M A, et al.
(författare)
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Symmetries and the Polarized Optical Spectra of Exciton Complexes in Quantum Dots
- 2011
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 107:12, s. 127403-
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Tidskriftsartikel (refereegranskat)abstract
- A systematic and simple theoretical approach is proposed to analyze true degeneracies and polarized decay patterns of exciton complexes in semiconductor quantum dots. The results provide reliable spectral signatures for efficient symmetry characterization, and predict original features for low C(2 nu) and high C(3 nu) symmetries. Excellent agreement with single quantum dot spectroscopy of real pyramidal InGaAs/AlGaAs quantum dots grown along [111] is demonstrated. The high sensitivity of biexciton quantum states to exact high symmetry can be turned into an efficient uninvasive postgrowth selection procedure for quantum entanglement applications.
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| 9. |
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| 10. |
- Karlsson, Fredrik, et al.
(författare)
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Fine structure of exciton complexes in high-symmetry quantum dots: Effects of symmetry breaking and symmetry elevation
- 2010
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Ingår i: PHYSICAL REVIEW B. - : American Physical Society. - 1098-0121. ; 81:16, s. 161307-
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Tidskriftsartikel (refereegranskat)abstract
- Quantum dots (QDs) of high symmetry (e.g., C-3 nu) have degenerate bright exciton states, unlike QDs of C-2 nu symmetry, making them intrinsically suitable for the generation of entangled photon pairs. Deviations from C-3 nu symmetry are detected in real QDs by polarization-resolved photoluminescence spectroscopy in side-view geometry of InGaAs/AlGaAs dots formed in tetrahedral pyramids. The theoretical analysis reveals both an additional symmetry plane and weak symmetry breaking, as well as the interplay with electron-hole and hole-hole exchange interactions manifested by the excitonic fine structure.
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| 11. |
- Karlsson, K Fredrik, et al.
(författare)
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Spectral signatures of high-symmetry quantum dots and effects of symmetry breaking
- 2015
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Ingår i: New Journal of Physics. - : Institute of Physics Publishing (IOPP). - 1367-2630. ; 17:10
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Tidskriftsartikel (refereegranskat)abstract
- High symmetry epitaxial quantum dots (QDs) with three or more symmetry planes provide a very promising route for the generation of entangled photons for quantum information applications. The great challenge to fabricate nanoscopic high symmetry QDs is further complicated by the lack of structural characterization techniques able to resolve small symmetry breaking. In this work, we present an approach for identifying and analyzing the signatures of symmetry breaking in the optical spectra of QDs. Exciton complexes in InGaAs/AlGaAs QDs grown along the [111]B crystalline axis in inverted tetrahedral pyramids are studied by polarization resolved photoluminescence spectroscopy combined with lattice temperature dependence, excitation power dependence and temporal photon correlation measurements. By combining such a systematic experimental approach with a simple theoretical approach based on a point-group symmetry analysis of the polarized emission patterns of each exciton complex, we demonstrate that it is possible to achieve a strict and coherent identification of all the observable spectral patterns of numerous exciton complexes and a quantitative determination of the fine structure splittings of their quantum states. This analysis is found to be particularly powerful for selecting QDs with the highest degree of symmetry ( C 3 v and ##IMG## [http://ej.iop.org/images/1367-2630/17/10/103017/njp519062ieqn1.gif] $D_3h$ ) for potential applications of these QDs as polarization entangled photon sources. We exhibit the optical spectra when evolving towards asymmetrical QDs, and show the higher sensitivity of certain exciton complexes to symmetry breaking.
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| 12. |
- Karlsson, K Fredrik, et al.
(författare)
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Symmetry Elevation and Symmetry Breaking : Keys to Describe and Explain Excitonic Complexes in Semiconductor Quantum Dots
- 2011
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X.
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Konferensbidrag (refereegranskat)abstract
- The results of a group theoretical analysis of the excitonic fine structure are presented and compared with spectroscopic data on single quantum dots. The spectral features reveal the signatures of a symmetry higher than the crystal symmetry (C 3v ). A consistent picture of the fine structure patterns for various exciton complexes is obtained with group theory and the concepts of symmetry elevation and symmetry breaking.
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| 13. |
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| 14. |
- Malafronte, Loredana, 1986, et al.
(författare)
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Combined convective and microwave assisted drying: Experiments and modelling
- 2012
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774 .- 1873-5770. ; 112:4, s. 304-312
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Tidskriftsartikel (refereegranskat)abstract
- The drying process is largely used in many different industrial applications, such as treatment of foods,production of cosmetics and pharmaceuticals, manufacturing of paper, wood and building materials,polymers and so on.Physical and mathematical models can constitute useful tools to establish the influence of the main process variables on the final product quality, in order to apply an effective production control. In this work, simulation model was developed to describe combined convective/microwave assisted drying. In particular, a multi-physics approach was applied to take into account heat and two mass balances (for liquid water and for water vapor) and Maxwell’s equations to describe electromagnetic field propagation.Potato matrix was selected as food material; a waveguide with a rectangular cross section, equipped with a hot air circulator device, was used as microwave applicator. The proposed model was found able to describe the process, being thus a useful tool for design and management of the process itself.
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| 15. |
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| 16. |
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| 17. |
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| 18. |
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| 19. |
- Agekyan, V F, et al.
(författare)
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Effect of a magnetic field on energy transfer of band states to the Mn2+ 3d shell in the CdMgTe matrix with ultrathin CdMnTe layers
- 2010
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Ingår i: PHYSICS OF THE SOLID STATE. - 1063-7834. ; 52:1, s. 27-31
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Tidskriftsartikel (refereegranskat)abstract
- The effect of external magnetic fields on two radiative (band-to-band and on-site) recombination channels in II-VI dilute magnetic semiconductors and related nanostructures has been considered. The 3d on-site emission of manganese ions in CdMgTe matrices containing periodic inclusions of CdMnTe narrow-band-gap layers with thicknesses of 0.5, 1.5, and 3.0 monolayers has been investigated in magnetic fields of up to 6 T. It has been shown that, in a magnetic field, luminescence of manganese ions weakens because of the decrease in the rate of spin-dependent excitation transfer from band states to the Mn2+ 3d shell. The maximum suppression of 3d luminescence has been observed in the matrix with a CdMnTe layer 3.0 monolayers thick. This indicates that the main factor responsible for the energy transfer is the internal field near the CdMnTe layers, which determines the magnetic splitting and spin polarization of band states.
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| 20. |
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| 21. |
- Agekyan, V F, et al.
(författare)
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Magnetoluminescence of CdTe/MnTe/CdMgTe heterostructures with ultrathin MnTe layers
- 2011
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Ingår i: Semiconductors (Woodbury, N.Y.). - : MAIK Nauka/Interperiodica (and#1052;and#1040;and#1048;and#1050; and#1053;and#1072;and#1091;and#1082;and#1072;/and#1048;and#1085;and#1090;and#1077;and#1088;and#1087;and#1077;and#1088;and#1080;and#1086;and#1076;and#1080;and#1082;and#1072;). - 1063-7826 .- 1090-6479. ; 45:10, s. 1301-1305
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Tidskriftsartikel (refereegranskat)abstract
- CdTe/MnTe/CdMgTe quantum-well structures with one or two monolayers of MnTe inserted at CdTe/CdMgTe interfaces were fabricated. The spectra of the excitonic luminescence from CdTe quantum wells and their variation with temperature indicate that introduction of ultrathin MnTe layers improves the interface quality. The effect of a magnetic field in the Faraday configuration on the spectral position of the exciton-emission peaks indicates that frustration of magnetic moments in one-monolayer MnTe insertions is weaker than in two-monolayer insertions. The effect of a magnetic field on the exciton localization can be explained in terms of the exciton wave-function shrinkage and obstruction of the photoexcited charge-carrier motion in the quantum well.
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| 22. |
- Aleksandrov, I.A., et al.
(författare)
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Linearly polarized photoluminescence from an ensemble of wurtzite GaN/AlN quantum dots
- 2010
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Ingår i: JETP Letters. - : Springer Science Business Media. - 0021-3640 .- 1090-6487. ; 91:9, s. 452-454
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Tidskriftsartikel (refereegranskat)abstract
- Microphotoluminescence from GaN/AlN quantum dots grown by molecular beam epitaxy on sapphire substrates along the (0001) axis has been studied. To produce quantum dots of different average sizes and densities, the nominal amount of deposited GaN has been varied from 1 to 4 ML. The density of the quantum dots was about 10(11) cm(-2), which corresponded to about 10(3) quantum dots excited in the experiments. The photo-luminescence from the quantum dots was linearly polarized and the maximum polarization degree (15%) has been observed for the sample with the lowest amount of deposited GaN. The photoluminescence intensity from this sample under continuous laser excitation decreased by more than two orders of magnitude for about 30 min and then stabilized. The photoluminescence intensity from other samples under continuous excitation remained constant. We suggest that a rather high polarization degree is caused by anisotropy in the strain and shape of the quantum dots formed near the dislocations, which also act as the centers of nonradiative recombination.
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| 23. |
- Chen, Yen-Ting, et al.
(författare)
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Nucleation of single GaN nanorods with diameters smaller than 35 nm by molecular beam epitaxy
- 2013
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 103:20, s. 203108-
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Tidskriftsartikel (refereegranskat)abstract
- Nucleation mechanism of catalyst-free GaN nanorod grown on Si(111) is investigated by the fabrication of uniform and narrow (andlt; 35 nm) nanorods without a pre-defined mask by molecular beam epitaxy. Direct evidences show that the nucleation of GaN nanorods stems from the sidewall of the underlying islands down to the Si(111) substrate, different from commonly reported ones on top of the island directly. Accordingly, the growth and density control of the nanorods is exploited by a "narrow-pass" approach that only narrow nanorod can be grown. The optimal size of surrounding non-nucleation area around single nanorod is estimated as 88 nm.
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| 24. |
- Eriksson, Martin O., et al.
(författare)
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Recombination processes in Mg doped wurtzite InN films with p- and n-type conductivity
- 2019
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Ingår i: AIP Advances. - : AMER INST PHYSICS. - 2158-3226. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Obtaining high quality, wurtzite InN films with p-type conductivity is a challenge, and there is limited information about the photoluminescence (PL) characteristics of such films. In this study, we present a comprehensive PL study and discuss in detail the recombination processes in Mg-doped InN films with varying Mg concentrations. We find that at low Mg-doping of 1x10(18) cm(-3), which yields p-type conductivity, the PL in InN is spatially inhomogeneous. The latter is suggested to be associated with the presence of n-type pockets, displaying photoluminescence at 0.73 eV involving electrons at the Fermi edge above the conduction band edge. Increasing the Mg concentration to 2.9x10(19) cm(-3) in p-type InN yields strong and spatially uniform photoluminescence at 0.62 eV and 0.68 eV visible all the way to room temperature, indicating homogeneous p-type conductivity. An acceptor binding energy of 64 meV is determined for the Mg acceptor. Further increase of the Mg concentration to 1.8x10(20) cm(-3) leads to switching conductivity back to n-type. The PL spectra in this highly doped sample reveal only the emission related to the Mg acceptor (at 0.61 eV). In the low-energy tail of the emission, the multiple peaks observed at 0.54 - 0.58 eV are suggested to originate from recombination of carriers localized at stacking faults. (C) 2019 Author(s).
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| 25. |
- Fahlvik, A K, et al.
(författare)
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Magnetic starch microspheres, efficacy and elimination. A new organ-specific contrast agent for magnetic resonance imaging
- 1990
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Ingår i: Investigative Radiology. - 0020-9996. ; 25:2, s. 113-120
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Tidskriftsartikel (refereegranskat)abstract
- A new particulate magnetic resonance (MR) contrast agent was prepared by controlled precipitation of iron oxide in an aqueous starch solution. The potential of the magnetic starch microspheres (MSM) as a hepatosplenic contrast enhancer was studied by MR spectroscopy and MR imaging. Intravascular administration of MSM to rodents showed an effective blood clearance and a tissue-specific localization of the substance. MSM doses in a range of 0.3-1.5 mg Fe/kg caused a 50% alteration in sensitive contrast parameters (ED50 doses) of liver and spleen. The contrast effect of MSM in liver and spleen was halved within 2 to 5 days. The approximated lethal MSM dose in mice was 150-200 mg Fe/kg. MSM is a tissue-specific MR contrast substance with high efficacy, rapid bioelimination, and low acute toxicity.
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| 26. |
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| 27. |
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| 28. |
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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. |
- Hippe, Andreas, et al.
(författare)
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EGFR/Ras-induced CCL20 production modulates the tumour microenvironment.
- 2020
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Ingår i: British Journal of Cancer. - : Springer Science and Business Media LLC. - 0007-0920 .- 1532-1827. ; 123:6, s. 942-954
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The activation of the EGFR/Ras-signalling pathway in tumour cells induces a distinct chemokine repertoire, which in turn modulates the tumour microenvironment.METHODS: The effects of EGFR/Ras on the expression and translation of CCL20 were analysed in a large set of epithelial cancer cell lines and tumour tissues by RT-qPCR and ELISA in vitro. CCL20 production was verified by immunohistochemistry in different tumour tissues and correlated with clinical data. The effects of CCL20 on endothelial cell migration and tumour-associated vascularisation were comprehensively analysed with chemotaxis assays in vitro and in CCR6-deficient mice in vivo.RESULTS: Tumours facilitate progression by the EGFR/Ras-induced production of CCL20. Expression of the chemokine CCL20 in tumours correlates with advanced tumour stage, increased lymph node metastasis and decreased survival in patients. Microvascular endothelial cells abundantly express the specific CCL20 receptor CCR6. CCR6 signalling in endothelial cells induces angiogenesis. CCR6-deficient mice show significantly decreased tumour growth and tumour-associated vascularisation. The observed phenotype is dependent on CCR6 deficiency in stromal cells but not within the immune system.CONCLUSION: We propose that the chemokine axis CCL20-CCR6 represents a novel and promising target to interfere with the tumour microenvironment, and opens an innovative multimodal strategy for cancer therapy.
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| 34. |
- Holtz, A, et al.
(författare)
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Blocking weight-induced spinal cord injury in rats : effects of TRH or naloxone on motor function recovery and spinal cord blood flow.
- 1989
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Ingår i: Acta Neurologica Scandinavica. - 0001-6314 .- 1600-0404. ; 80:3, s. 215-20
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Tidskriftsartikel (refereegranskat)abstract
- The ability of thyrotropin releasing hormone (TRH) or naloxone to reduce the motor function deficit and to improve the spinal cord blood flow (SCBF) was investigated in a rat spinal cord compression injury model. Spinal cord injury was induced by compression for 5 min with a load of 35 g on a 2.2 x 5.0 mm sized compression plate causing a transient paraparesis. One group of animals was given TRH, one group naloxone and one group saline alone. Each drug was administered intravenously as a bolus dose of 2 mg/kg 60 min after injury followed by a continuous infusion of 2 mg/kg/h for 4 h. The motor performance was assessed daily on the inclined plane until Day 4, when SCBF was measured with the 14C-iodoantipyrine autoradiographic method. It was found that neither TRH nor naloxone had promoted motor function recovery or affected SCBF 4 days after spinal cord injury.
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| 35. |
- Holtz, A, et al.
(författare)
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Blocking weight-induced spinal cord injury in rats : therapeutic effect of the 21-aminosteroid U74006F.
- 1991
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Ingår i: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 8:4, s. 239-45
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Tidskriftsartikel (refereegranskat)abstract
- The effect of the 21-aminosteroid U74006F on neurologic recovery after a spinal cord compression trauma was investigated in rats. The compression was induced by a blocking weight technique, in which a 35 g (moderate injury) or a 50 g (severe injury) weight was applied for 5 minutes to an 11 mm2 plate over the midthoracic spinal cord. One hour after trauma, the severely injured animals were treated either with U74006F, 3 mg/kg, methylprednisolone, 30 mg/kg, or vehicle, whereas the moderately injured animals received U74006F, 3 mg/kg or vehicle. Neurologic hind limb function was evaluated by the inclined plane technique. On day 1 after trauma, subtotal paraparesis occurred in the 35 g group treated with vehicle (31 +/- 1 degrees, mean +/- SEM) on the inclined plane vs 64 +/- 1 degrees before trauma) and complete paraplegia in the 50 g group (22 +/- 1 degrees). Treatment with U74006F resulted in less hind limb weakness in the 35 g group (42 +/- 2 degrees) but had no beneficial effect in the 50 g group (25 +/- 2 degrees). Neurologic function gradually improved in the 35 g groups over the 9-day observation period. However, those animals treated with U74006F were significantly better over the entire period. In the 50 g group, no recovery from paraplegia was noted over the 4 day observation period in any of the three groups. These results suggest that after weight-induced spinal cord trauma, U74006F is associated with improved neurologic function in moderately injured, but not severely injured animals.
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| 36. |
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| 37. |
- Holtz, A, et al.
(författare)
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Effect of methylprednisolone on motor function and spinal cord blood flow after spinal cord compression in rats.
- 1990
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Ingår i: Acta Neurologica Scandinavica. - 0001-6314 .- 1600-0404. ; 82:1, s. 68-73
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Tidskriftsartikel (refereegranskat)abstract
- The effect of methylprednisolone (MP) on neurologic recovery and spinal cord blood flow (SCBF) was investigated up to 4 days after a spinal cord compression injury in rats. The injury was produced at midthoracic level by applying a load of 35 g on a 2.2 x 5.0 mm compression plate for 5 min, which resulted in transient paraparesis. MP was given as a bolus dose of 30 mg/kg i.v. 60 min after injury (n = 20) and controls were given saline (n = 10). The motor performance was assessed daily as the capacity angle on the inclined plane and SCBF was measured by 14C-iodoantipyrine autoradiography on Days 1 or 4. On Day 1 the capacity angle was reduced from about 63 degrees preoperatively to 33 +/- 2 degrees (mean +/- SEM) in the control group and to 50 +/- 1 degrees in the group treated with MP (p less than 0.05). Thereafter there was a slight improvement in both groups, but the difference persisted throughout the observation period. On Day 4 both gray and white matter SCBF was better preserved in MP-treated animals than in the control group (59 +/- 4 versus 49 +/- 3 ml/min/100 g tissue for gray matter and 13.6 +/- 0.6 versus 10.7 +/- 0.8 ml/min/100 g tissue for white matter). Posttraumatic treatment with MP, thus, improved both the neurologic recovery during the first 4 days and SCBF as measured on Day 4. It is speculated that the effect of MP is at least partly exerted on the vascular bed.
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| 38. |
- Holtz, A, et al.
(författare)
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Efficacy of the 21-aminosteroid U74006F in improving neurological recovery after spinal cord injury in rats.
- 1992
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Ingår i: Neurological Research. - 0161-6412 .- 1743-1328. ; 14:1, s. 49-52
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Tidskriftsartikel (refereegranskat)abstract
- The efficacy of three different regimens of the 21-aminosteroid U74006F in counteracting the neurological damage after spinal cord compression causing paraparesis in rats was investigated. Three groups of ten animals each were given totally 6 mg/kg of U74006F in different regimens beginning one hour after injury (A: bolus doses of 1.5 mg/kg at 1, 4, 7 and 10 hours; B: bolus of 1.5 mg/kg at 1 hour and 4.5 mg/kg as an infusion over the next 9 hours; and C: infusion alone, 6 mg/kg, given between 1 and 10 hours after trauma). Two groups of ten animals each received vehicle alone in administration modes comparable to those of the U74006F treated animals. The motor function was assessed daily on the inclined plane. On day one, the capacity angle had decreased from about 62 degrees preoperatively to 28-30 degrees in the two vehicle-treated groups and in group C. In these groups there was a similar improvement in neurological function and on day 9 the capacity angles were 49-55 degrees. In groups A and B, both of which received a bolus dose of U74006F at 1 hour, the neurological outcome improved on day one with capacity angles of 38-40 degrees. The difference in neurological function between the animals given U74006F as bolus doses and those given vehicle alone persisted over the entire observation span until day 9. The data suggest that early treatment with a bolus dose seems to be required in order to obtain an effect of U74006F on neurological recovery.
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| 39. |
- Holtz, A, et al.
(författare)
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MK 801, an OBS N-methyl-D-aspartate channel blocker, does not improve the functional recovery nor spinal cord blood flow after spinal cord compression in rats.
- 1991
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Ingår i: Acta Neurologica Scandinavica. - 0001-6314 .- 1600-0404. ; 84:4, s. 334-8
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Tidskriftsartikel (refereegranskat)abstract
- Damage to the central nervous system is followed by local release of excitatory amino acids, e.g. glutamate. These have been claimed to increase the metabolic need of already hypoxic neurons, and thereby to promote cell death. To investigate whether N-methyl-D-aspartate (NMDA) receptor-mediated mechanisms are involved in the damage consequent to spinal cord injury, 20 rats were exposed to 5-min compression of the thoracic spinal cord produced with a load of 35 g on a 2.2 x 5 mm sized plate. One group of animals was given a noncompetitive NMDA channel blocker, MK-801, in a dose of 10 mg/kg b.w and one group saline alone. The neurologic function was evaluated on the inclined plane for 4 days when spinal cord blood flow (SCBF) was measured with the 14C-iodoantipyrine autoradiographic technique. One day after trauma the animals in both groups were paraparetic and exhibited a significantly decreased capacity angle at the inclined plane test (about 35 degrees compared with about 63 degrees before compression). Thereafter, the motor function improved slightly, but to a similar extent in the two groups. On Day 4, gray and white matter SCBF was similar in the two groups. The results indicate that MK 801 in the dose used does not prevent the development of neurologic dysfunction or the reduction in SCBF after spinal cord compression.
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| 40. |
- Holtz, A, et al.
(författare)
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Neuropathological changes and neurological function after spinal cord compression in the rat.
- 1990
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Ingår i: Journal of Neurotrauma. - : Mary Ann Liebert Inc. - 0897-7151 .- 1557-9042. ; 7:3, s. 155-67
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Tidskriftsartikel (refereegranskat)abstract
- As part of a series of experimental investigations of the effects of various pharmacological agents on the outcome of compressive spinal cord trauma in the rat, the time course of the cell changes in the cord at the site of and distal to the compression was studied at the light microscopic level. The degree of compression used with the present model results in a transient paraparesis that recovers almost completely over a period of 3 weeks as judged by the inclined plane technique. The most significant morphological findings were as follows. Initially (1 and 24 h after the impact) there was pronounced swelling and hemorrhage at the compression site, chiefly in the gray matter of the cord. On day 4 there was severe necrosis in the same region, with numerous macrophages and leukocytes. Rats killed after 21 days showed either minor residual signs of necrosis or essentially normal tissue architecture. Surprisingly, necrosis with delayed onset also developed in the dorsal columns, involving the pyramidal tracts. This necrosis was detected in animals killed after 9 and 21 days but not in those observed after 4 days or earlier. The longitudinal tracts of the white matter showed reduced staining in paraffin sections of the compression site. Epon sections revealed splits in the myelin sheaths and enlarged periaxonal spaces as early as 1 h after the impact. The alterations in the longitudinal tracts persisted throughout the 21-day observation period and extended down to L2-L4. There was gradual functional recovery, documented by the inclined plane test. Preinjury values were almost reached on day 21, although the cord still showed some morphological damage. In individual animals, no relation was found between degree of function as tested by inclined plane and extent of morphologic injury. Additional functional and morphological methods obviously are needed in future investigations of the effects of treatments on the outcome of compressive spinal cord injury.
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| 41. |
- Holtz, A, et al.
(författare)
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Regulation of spinal cord blood flow in the rat as measured by quantitative autoradiography.
- 1988
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Ingår i: Acta Physiologica Scandinavica. - : Wiley. - 0001-6772 .- 1365-201X. ; 133:4, s. 485-93
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Tidskriftsartikel (refereegranskat)abstract
- Spinal cord blood flow (SCBF) and its response to alterations in blood gases and to systemic hypotension, haemodilution and barbiturate anaesthesia were measured in 47 rats at the level of Th 7-8 by quantitative autoradiography with [14C]iodoantipyrine ([14C]IAP) as tracer. During normocapnia and normoxia the mean SCBF values in the grey and white matter were 94 +/- 21 and 17 +/- 3 ml min-1 100 g-1, respectively. SCBF was highly dependent on PaCO2. Thus in hypercapnic animals (PaCO2 greater than 9 kPa) SCBF was increased in grey and white matter to 228 +/- 22 and 54 +/- 7 ml min-1 100 g-1, while during hypocapnia (PaCO2 less than 3.9 kPa) it was decreased to 64 +/- 14 and 11 +/- 2 ml min-1 100 g-1, respectively. Mean arterial blood pressure (MABP) was reduced by withdrawal of blood to 80 +/- 8 mmHg in a light hypotension group and to 53 +/- 11 mmHg in a severe hypotension group, compared with 126 +/- 13 mmHg in a control group. There was no significant difference in SCBF between the control group and the hypotension groups, suggesting that autoregulation is maintained down to an MABP of at least 50 mmHg. Normovolaemic haemodilution, with a reduction of the haematocrit from 50 +/- 2 to 33 +/- 3, increased SCBF to 113 +/- 9 ml min-1 100 g-1 in grey matter and to 21 +/- 12 ml min-1 100 g-1 in white matter.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 42. |
- Holtz, A, et al.
(författare)
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Relation between spinal cord blood flow and functional recovery after blocking weight-induced spinal cord injury in rats.
- 1990
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Ingår i: Neurosurgery. - 0148-396X .- 1524-4040. ; 26:6, s. 952-7
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Tidskriftsartikel (refereegranskat)abstract
- Spinal cord blood flow (SCBF) and motor performance on the inclined plane were measured up to 9 days after a reversible spinal cord compression injury in 49 Sprague-Dawley rats. A load of 35 g on 11 mm2 of the thoracic spinal cord for 5 minutes caused transient paraparesis with a decrease in the capacity angle on the inclined plane from 62 +/- 1 degree (mean +/- SEM) before injury to 33 +/- 1 degree on Day 1, 45 +/- 2 degrees on Day 4, d and 54 +/- 3 degrees on Day 9. SCBF was measured by the [14C]iodoantipyrine method, and in gray matter there was a decrease from 78.4 +/- 2.3 ml/min/100 g of tissue in uninjured animals to 33.7 +/- 1.5 ml/min/100 g of tissue on Day 1 after injury, increasing to 50.1 +/- 2.0 on Day 4 and to 70.5 +/- 2.7 ml/min/100 g of tissue on Day 9. At the corresponding times, the SCBF values in white matter were 14.5 +/- 0.5, 6.7 +/- 0.5, 10.2 +/- 0.6, and 13.4 +/- 0.6 ml/min/100 g of tissue, respectively. The animals in another group were loaded with 25 g for 5 minutes and on Day 1 exhibited a capacity angle of 43 +/- 2 degrees while the SCBF values for gray and white matter were 55.1 +/- 2.0 and 11.1 +/- 0.4 ml/min/100 g of tissue, respectively; thus, the results in this group were similar to the values on Day 4 in the animals loaded with 35 g.(ABSTRACT TRUNCATED AT 250 WORDS)
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| 43. |
- Holtz, A, et al.
(författare)
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Spinal cord blood flow measured by 14C-iodoantipyrine autoradiography during and after graded spinal cord compression in rats.
- 1989
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Ingår i: Surgical Neurology. - 0090-3019 .- 1879-3339. ; 31:5, s. 350-60
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Tidskriftsartikel (refereegranskat)abstract
- The relations between degree of thoracic spinal cord compression causing myelographic block, reversible paraparesis, and extinction of the sensory evoked potential on one hand, and spinal cord blood flow on the other, were investigated. This was done in rats using the blocking weight-technique and 14C-iodoantipyrine autoradiography. A load of 9 g caused myelographic block. Five minutes of compression with that load caused a reduction of spinal cord blood flow to about 25%, but 5 and 60 minutes after the compression spinal cord blood flow was restored to 60% of the pretrauma value. A load of 35 g for 5 minutes caused transient paraparesis. Recovery to about 30% was observed 5 and 60 minutes thereafter. During compression at a load of 55 g, which caused almost total extinction of sensory evoked potential and irreversible paraplegia, spinal cord blood flow under the load ceased. The results indicate that myelographic block occurs at a load which does not cause irreversible paraparesis and that a load which permits sensory evoked potential to be elicited results in potentially salvageable damage.
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| 44. |
- Holtz, A, et al.
(författare)
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Spinal cord injury in rats : inability of nimodipine or anti-neutrophil serum to improve spinal cord blood flow or neurologic status.
- 1989
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Ingår i: Acta Neurologica Scandinavica. - 0001-6314 .- 1600-0404. ; 79:6, s. 460-7
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Tidskriftsartikel (refereegranskat)abstract
- The role of a calcium-mediated increase in vascular resistance and of vascular damage caused by polymorphonuclear leukocytes (PMNLs) in the development of neurologic deficit and disturbance of spinal cord circulation following spinal cord compression was studied in the rat. Spinal cord injury was induced by 5 min of compression with a load of 35 g on a 2.2 X 5.0 mm compression plate. This caused transient paraparesis. The rats received either the calcium receptor antagonist nimodipine or an anti-rat neutrophil serum (ANS). Nimodipine was infused i.v. for 4 h in an amount of 1.5 micrograms/kg/min starting 60 min after trauma. The number of circulating PMNLs was depleted by intraperitoneal injection of an ANS raised in sheep given 12 h before trauma. This caused a reduction to about 2% of the pre-ANS value. Controls received saline or normal sheep serum. The motor performance was assessed daily on the inclined plane. On day one, the day after injury, the capacity angle had decreased from about 63 degrees preoperatively to close to 32 degrees in the experimental groups. There was then a slow improvement in both the control and experimental groups and on day 4 the capacity angle was close to 43 degrees in all 3 groups. Spinal cord blood flow, as measured with the 14C-iodoantipyrine autoradiography method, was similar in all groups on day 4. As neither the neurologic dysfunction nor the spinal cord blood flow was affected by post-trauma treatment with nimodipine or pretreatment with ANS, the possibility that calcium-mediated vasoconstriction or PMNLs play a role in the development of posttraumatic neurologic disability was not supported by this study.
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| 45. |
- Holtz, Per-Olof, et al.
(författare)
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Optical characterization of individual quantum dots
- 2012
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Ingår i: Physica. B, Condensed matter. - : Elsevier. - 0921-4526 .- 1873-2135. ; 407:10, s. 1472-1475
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Tidskriftsartikel (refereegranskat)abstract
- Optical characterization of single quantum dots (QDs) by means of micro-photoluminescence (mu PL) will be reviewed. Both QDs formed in the Stranski-Krastanov mode as well as dots in the apex of pyramidal structures will be presented. For InGaAs/GaAs dots, several excitonic features with different charge states will be demonstrated. By varying the magnitude of an external electric or magnetic field and/or the temperature, it has been demonstrated that the transportation of carriers is affected and accordingly the charge state of a single QD can be tuned. In addition, we have shown that the charge state of the QD can be controlled also by pure optical means, i.e. by altering the photo excitation conditions. Based on the experience of the developed InAs/GaAs QD system, similar methods have been applied on the InGaN/GaN QD system. less thanbrgreater than less thanbrgreater thanThe coupling of LO phonons to the QD emission is experimentally examined for both charged and neutral excitons in single InGaAs/GaAs QDs in the apex of pyramidal structures. It is shown that the positively charged exciton exhibits a significantly weaker LO phonon coupling in the mu PL spectra than the neutral and negatively charged species, a fact, which is in consistency with model simulations performed.
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| 46. |
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| 47. |
- Hsu, Chih-Wei
(författare)
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InGaN Quantum Dots Grown on GaN Pyramid Arrays
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Selective-area growth (SAG) of InGaN on GaN pyramids, which allows the formation of additional hybrid quantum structures, including quantum wires and quantum dots (QDs) in a site-controlled fashion, is attractive for both fundamental research and device application. The site-controlled growth of QDs showing sharp emission lines is seen as the first step toward the frontier quantum information application (QIA). Note that, in such case, one QD represents one device unless the challenge of fabricating identical QDs is overcome.The concept of SAG GaN pyramids hosting InGaN QDs has been reported since 2000. However, the observation of sharp emission lines, which can be ascribed to three-dimensional carrier confinement in QDs, seems to be occasional.The main outcome of this work is the investigation of the InGaN QDs grown on GaN hexagonal pyramids. This work covers the formation mechanism of InGaN QDs to the emission properties of individual InGaN QDs. A modified SAG approach to obtain InGaN QDs emitting photons with heralded polarization directions is also demonstrated. The inherent high polarization degree of photons emitted by InGaN QDs together with heralded polarization direction reveals a promising potential for the direct generation of linearly-polarized photons by site-controlled InGaN QDs.
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| 48. |
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| 49. |
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| 50. |
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