| 1. |
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| 2. |
- Montelius, L., et al.
(author)
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Pattern recognition of nerve signals using an artificial neural network
- 1996
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In: ; , s. 1502-1503
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Conference paper (peer-reviewed)abstract
- By using a microfabricated nerve chip with integrated electrodes through which peripheral nerves can generate and make electrical connects, it should be possible to control a remote prosthesis by processing the detected nerve signals. In this study different artificial neural networks have been employed for classification of such complex patterns of signals. The signals were obtained from four electrodes detecting muscle activity in a rat hindlimb as a consequence of applied stimulus to the rat right hindpaw. These signals recorded at four different sites resembles a situation of a nerve chip with four electrodes, which implies that we might be able to use the same strategy when analyzing data from a four-electrode chip to obtain information from the nervous system. In this paper we will address the usefulness of different network topologies for analyzing measured in-vivo data from an implanted perforated nerve chip.
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| 3. |
- Carlsson, N, et al.
(author)
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IMPROVED SIZE HOMOGENEITY OF INP-ON-GAINP STRANSKI-KRASTANOW ISLANDS BY GROWTH ON A THIN GAP INTERFACE LAYER
- 1995
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In: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 156:1-2, s. 23-29
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Journal article (peer-reviewed)abstract
- Coherent InP nano-sized islands, embedded into GaInP, have been grown by metal-organic vapour phase epitaxy using the Stranski-Krastanow growth mode. Photoluminescence, atomic force microscopy and transmission electron microscopy studies show that the insertion of a thin ∼ 4 monolayer thick GaP layer affects the critical thickness of the subsequently deposited two-dimensional InP wetting layer, increasing it from ∼ 1.5 monolayers (without an inserted GaP layer) to ∼ 2.5 monolayers (with an inserted GaP layer). We demonstrate that the inserted GaP layer affects also the island formation. The bimodal size distribution of Stranski-Krastanow islands, typical for low InP coverages, can be overcome without island coalescence by deposition on top of the thin GaP layer, where a coverage of InP of about 3.5–4.5 monolayers results in the formation of almost only the larger, fully developed, pyramidal islands. Annealing experiments at growth temperature of 580°C show that these islands (base area ≈ 40 × 50 nm2, height ≈ 10–15 nm, surface density ≈ (1−2) × 109 cm−2) are rather stable in a time-scale over several minutes before they slowly undergo an Ostwald ripening process.
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| 4. |
- Malmqvist, L, et al.
(author)
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Liquid-target laser-plasma source for X-ray lithography
- 1997
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In: Microelectronic Engineering. - 1873-5568. ; 35:1-4, s. 535-536
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Journal article (peer-reviewed)abstract
- We describe a compact and practically debris-free laser-plasma x-ray source suitable for proximity lithography. The source is based on a microscopic fluorocarbon continuous liquid jet droplet target, generating high-brightness lambda=1.2-1.7 nm x-ray emission with similar to 5% conversion efficiency. This target type has the advantages of producing only negligible amounts of debris, and being regenerative, thereby allowing high-repetition-rate uninterrupted operation. The source is combined with an Au/SiNx x-ray mask to demonstrate lithography of sub-100 nm structures in SAL-601 chemically enhanced resist.
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| 5. |
- Malmqvist, L, et al.
(author)
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Nanometer table-top proximity x-ray lithography with liquid-target laser-plasma source
- 1997
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In: Journal of Vacuum Science and Technology B. - : American Vacuum Society. - 1520-8567. ; 15:4, s. 814-817
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Journal article (peer-reviewed)abstract
- A compact laser-plasma proximity x-ray lithography system suitable for laboratory-scale low-volume nanometer patterning is presented. The laser-plasma source, which is based on a fluorocarbon liquid-jet target, generates high-brightness lambda = 1.2-1.7 nm x-ray emission with only negligible debris production. The Au/SiNx x-ray mask is fabricated by employing ion milling and a high-contrast e-beam resist. With SAL-601 chemically enhanced resist we demonstrate fabrication of high-aspect-ratio, sub-100 nm structures. The exposure time is currently 20 min using a compact 10 Hz, lambda = 532 nm, 70 mJ/pulse mode-locked Nd:YAG laser. However, the regenerative liquid-jet target is designed for operation with future, e.g., 1000 Hz, lasers resulting in projected exposure times of similar to 10 s. (C) 1997 American Vacuum Society.
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| 6. |
- MONTELIUS, L, et al.
(author)
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CHARACTERIZATION OF THE MN ACCEPTOR LEVEL IN GAAS
- 1988
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In: Journal of Applied Physics. - CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 : AIP Publishing. - 0021-8979 .- 1089-7550. ; 64, s. 1564-1567
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Journal article (peer-reviewed)
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| 7. |
- Wallman, L, et al.
(author)
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Perforated silicon nerve chips with doped registration electrodes : in vitro performance and in vivo operation
- 1999
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In: IEEE Transactions on Biomedical Engineering. - 1558-2531. ; 46:9, s. 73-1065
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Journal article (peer-reviewed)abstract
- An in vitro model was developed for the study of signal transduction between a Cu-wire, miming a neural signal source, and recording electrodes on perforated silicon chips. Phosphorous doped electrodes were used to achieve an all silicon device. The model was used to study signal amplitude as a function of the spatial position, and distance to the signal source. Recordings of the signal crosstalk to neighboring electrodes on the chips were made. It was found that the amplitude decreased by a factor of two at a distance of 50 microns between the electrode surface and the signal source. The chip electrode signal crosstalk was found to be 6 dB using an external reference electrode. Improvements were accomplished with an on chip reference electrode giving a crosstalk suppression of 20 dB. Impedance analysis showed that doped silicon electrodes displayed similar characteristics as Cu-electrodes at frequencies above 3 kHz. Sieve electrodes were implanted in the rat sciatic nerve and following a 10-week nerve regeneration period the dorsal and ventral (L5) roots in the spinal cord were stimulated. Compound action potentials were recorded via the chip. Stimulating the regenerated sciatic nerve via the sieve electrode also induced lower leg muscle contraction activity.
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| 8. |
- Wallman, L., et al.
(author)
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Silicon sieve electrodes for neural implants - in vitro characterization & in vivo recordings
- 1998
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In: Procceedings of the 20th Annual International Conference of the IEEE Engineering in Medicine and Biology Society : Biomedical Engineering Towards the Year 2000 and Beyond - Biomedical Engineering Towards the Year 2000 and Beyond. - 0780351649 ; 20, s. 2225-2228, s. 2225-2228
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Conference paper (peer-reviewed)abstract
- An in vitro model was developed to characterize the electrical properties of silicon microfabricated recording electrodes, using a Cu-wire mimicing a neural signal source. Phosphorous doped electrodes were used to achieve an all silicon device. The model was used to study signal amplitude as a function of distance between the electrode surface and the signal source. Signal crosstalk to neighbouring electrodes on the chips were recorded. The crosstalk was found to be 6 dB using an external reference electrode. Improvements were accomplished with an on chip reference electrode giving an amplitude crosstalk suppression of 20 dB. It was found that the amplitude decreased by a factor of 2 at a distance of 50 μm between the electrode surface and the signal source. Sieve electrodes were also implanted in the rat sciatic nerve and following a 10 week nerve regeneration period the dorsal and ventral (L5) roots in the spinal cord were stimulated. Compound action potentials were recorded via the chip. Lower leg muscle contraction activity was also induced by stimulating the regenerated sciatic nerve via the sieve electrode.
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| 13. |
- Bäck, S A, et al.
(author)
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Verification of single beam treatment planning using a ferrous dosimeter gel and MRI (FeMRI)
- 1998
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In: Acta Oncologica. - 0284-186X. ; 37:6, s. 6-561
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Journal article (peer-reviewed)abstract
- A method for analysing and comparing treatment planning system (TPS) data and ferrous dosimeter gel measurements evaluated with MRI (FeMRI) was developed, including image processing to final absorbed dose images. Measurements were analysed according to this method and FeMRI data were thereby compared with the TPS-calculated dose distribution. For photons, differences between FeMRI- and TPS dose data were mainly within +/- 2%. Minor shortcomings found in both the FeMRI system and the TPS are explained and discussed. For electron beams, there was an overall good agreement. It was found that the TPS underestimates the lateral scattering dose outside the primary beam, but the reported dose difference corresponds to a small spatial deviation (less than 2 mm). It is important to consider this single beam data comparison when the method is extended to more complicated situations, for example when using several beams.
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| 14. |
- Bäck, Sven, et al.
(author)
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Improvements in absorbed dose measurements for external radiation therapy using ferrous dosimeter gel and MR imaging (FeMRI)
- 1998
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In: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 43, s. 261-
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Journal article (peer-reviewed)abstract
- A ferrous gel, based on ferrous (Fe) sulphate and agarose, was used with a clinical magnetic resonance imaging (MRI) scanner to obtain relative dose distribution data from therapeutic photon and electron beams. The FeMRI gel was scanned using a new MRI acquisition protocol optimized for T1 measurements. Thorough comparisons with silicon semiconductor detector and ionization chamber measurements, as well as with Monte Carlo calculations, were performed in order to quantify the improvements obtained using FeMRI for dose estimations. Most of the relative doses measured with FeMRI were within 2% of the doses measured with other methods. The larger discrepancies (2-4%) found at shallow depths are discussed. The uncertainty in relative dose measurements using FeMRI was significantly improved compared with previously reported results (5-10%, one standard deviation, 1 SD), and is today between 1.6% and 3.3% (depending on dose level, 2 SD). This corresponds to an improvement in the minimum detectable dose (3 SD above background) from approximately 2 Gy to better than 0.6 Gy. The results obtained in this study emphasize the importance of obtaining basic FeMRI dose data before the method is extended to complicated treatment regimes.
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| 15. |
- Chaudhary, Shilpi, et al.
(author)
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Adsorption of 3-(triethoxysilyl)propionitrile on a rutile TiO2(110) surface : An X-ray photoelectron spectroscopy study
- 2020
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In: DAE Solid State Physics Symposium 2019. - : AIP Publishing. - 1551-7616 .- 0094-243X. - 9780735420250 ; 2265
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Conference paper (peer-reviewed)abstract
- The adsorption of 3-(triethoxysilyl)propionitrile (TESP) on a reduced rutile TiO2(110) surface has been investigated using synchrotron-based X-ray photoelectron spectroscopy in ultrahigh vacuum (UHV). We have studied TESP adsorption on two surface preparation of rutile TiO2 (110) to explore the role of surface defects. In the first preparation, the adsorption of TESP was studied on reduced TiO2 (110) surface at room temperature. In the second experiment TESP was adsorbed on the oxygen-treated TiO2 surface to quench the oxygen vacancies generated by UHVannealing of the TiO2 crystal. The molecular footprints of the TESP molecules confirms the adsorption on both types of TiO2(110) surfaces. In the case of the reduced surface, temperature-dependent XPS measurements show the thermal stability of TESP molecules up to 600 °C. The comparison of the nitrogen and carbon lineshapes for both preparations suggests different adsorption geometries on the reduced and oxygen-dosed surfaces. To the best of our knowledge, the UHV preparations and measurements of TESP adsorption on rutile TiO2 (110) in the present study are reported for the first time.
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| 20. |
- Gärdlund, B, et al.
(author)
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Randomised, controlled trial of low-dose heparin for prevention of fatal pulmonary embolism in patients with infectious diseases. The Heparin Prophylaxis Study Group.
- 1996
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In: The Lancet. - : Elsevier BV. - 0140-6736 .- 1474-547X. ; 347:9012, s. 1357-61
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Journal article (peer-reviewed)abstract
- BACKGROUND: Fatal pulmonary embolism and other thromboembolic complications are common in hospital inpatients. However, there is little evidence on the routine use of pharmacological thromboprophylaxis in non-surgical patients. We assessed the efficacy and safety of low-dose heparin in the prevention of hospital-acquired, clinically relevant, fatal pulmonary embolism in patients with infectious diseases.METHODS: Our study used the postrandomisation consent design. 19,751 consecutive patients, aged 55 years or older, admitted to departments of infectious diseases in six Swedish hospitals, were screened for inclusion in the randomised, controlled, unblinded, multicentre trial. Of the eligible patients, 5776 were assigned subcutaneous standard heparin (5000 IU every 12 h) until hospital discharge or for a maximum of 3 weeks; 5917 were assigned no prophylactic treatment (control group). We sought consent only from the heparin group. Follow-up was for 3 weeks after discharge from hospital or for a maximum of 60 days from randomisation. The primary endpoint was necropsy-verified pulmonary embolism of predefined clinical relevance.FINDINGS: By intention-to-treat analysis mortality was similar in the heparin and control groups (5.3 vs 5.6%, p = 0.39) and the median time from admission to death was 16 days in both groups (IQR 8-31 vs 6-28 days). Necropsy-verified pulmonary embolism occurred in 15 heparin-treated and 16 control-group patients. There was a significant difference between heparin and control groups in median time from randomisation to fatal pulmonary embolism (28 [24-36] vs 12.5 [10-20] days, p = 0.007). This difference corresponds to the duration of heparin prophylaxis. Non-fatal thromboembolic complications occurred in more of the control than of the heparin group (116 vs 70, p = 0.0012).INTERPRETATION: Our findings do not support the routine use of heparin prophylaxis for 3 weeks or less in large groups of non-surgical patients. Further studies are needed to investigate whether heparin prophylaxis of longer duration may prevent fatal pulmonary embolism.
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| 21. |
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| 22. |
- Jansson, John-Olov, 1954, et al.
(author)
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Body weight homeostat that regulates fat mass independently of leptin in rats and mice.
- 2018
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 115:2, s. 427-432
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Journal article (peer-reviewed)abstract
- Subjects spending much time sitting have increased risk of obesity but the mechanism for the antiobesity effect of standing is unknown. We hypothesized that there is a homeostatic regulation of body weight. We demonstrate that increased loading of rodents, achieved using capsules with different weights implanted in the abdomen or s.c. on the back, reversibly decreases the biological body weight via reduced food intake. Importantly, loading relieves diet-induced obesity and improves glucose tolerance. The identified homeostat for body weight regulates body fat mass independently of fat-derived leptin, revealing two independent negative feedback systems for fat mass regulation. It is known that osteocytes can sense changes in bone strain. In this study, the body weight-reducing effect of increased loading was lost in mice depleted of osteocytes. We propose that increased body weight activates a sensor dependent on osteocytes of the weight-bearing bones. This induces an afferent signal, which reduces body weight. These findings demonstrate a leptin-independent body weight homeostat ("gravitostat") that regulates fat mass.
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| 23. |
- Johansson, S A, et al.
(author)
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Dosimeter gel and MR imaging for verification of calculated dose distributions in clinical radiation therapy
- 1997
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In: Acta Oncologica. - 0284-186X. ; 36:3, s. 90-283
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Journal article (peer-reviewed)abstract
- A dosimeter gel, based on an agarose gel infused with a ferrous sulphate solution and evaluated in a magnetic resonance scanner, was used for complete verification of calculated dose distributions. Two standard treatment procedures, treatment of cancer in the urinary bladder and treatment of breast cancer after modified radical mastectomy, were examined using pixel-by-pixel and dose volume histogram comparison. The dose distributions calculated with the dose planning system was in very good agreement with the measured ones. However, in the case of the more complicated breast cancer treatment, some discrepancies were found, mainly at the beam abutment region. This may be explained by field displacements errors and by a small limitation of the dose planning utilising small electron beams in this region. The dosimeter gel system have proven to be a useful tool for dosimetry in clinical radiation therapy applications.
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| 24. |
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| 25. |
- Lundberg, F., et al.
(author)
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Protein depositions on one hydrocephalus shunt and on fifteen temporary ventricular catheters
- 1997
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In: Acta Neurochirurgica. - 0001-6268. ; 139:8, s. 734-742
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Journal article (peer-reviewed)abstract
- Biomaterials are commonly used in modern medicine. Proteins are adsorbed to the surface of the biomaterial immediately after insertion. This report demonstrates the presence of adsorbed proteins in one infected cerebrospinal shunt from a child with hydrocephalus and on fifteen temporary ventricular catheters from adult patients with spontaneous or traumatic brain injuries. Depositions of vitronectin, fibrinogen and thrombospondin-fibronectin to some extent - on the shunt surface was imaged by field-emission scanning electron microscopy. Vitronectin, fibronectin, fibrinogen, and thrombospondin on the ventricular catheters were shown with radio-actively labelled antibodies. Furthermore, protein adsorption from human cerebrospinal fluid to heparinized and unheparinized polymers was studied under flowing conditions in vitro. On heparinized polymer, significantly reduced levels of vitronectin, fibronectin, and thrombospondin were exposed, as measured after 4 hours in vitro perfusion. After 24 hours perfusion, the differences in protein exposition between heparinized and unheparinized polymers were substantially reduced.
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