| 1. |
- Andersson, Christer, 1982, et al.
(författare)
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A SiC Varactor With Large Effective Tuning Range for Microwave Power Applications
- 2011
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 32:6, s. 788-790
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Tidskriftsartikel (refereegranskat)abstract
- SiC Schottky diode varactors have been fabricated for use in microwave power applications, specifically the dynamic load modulation of power amplifiers. A custom doping profile has been employed to spread the C(V) over a large bias voltage range, thereby increasing the effective tuning range under large voltage swing conditions. The small-signal tuning range is approximately six, and punch through is reached at a bias voltage of -60 V, while the breakdown voltage is on the order of -160 V. An interdigitated layout is utilized together with a self-aligned Schottky anode etch process to improve the Q-factor at 2 GHz, which is 20 at zero bias and approximately 160 at punch through.
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| 2. |
- Andersson, Christer, 1982, et al.
(författare)
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Epitaxial and Layout Optimization of SiC Microwave Power Varactors
- 2011
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Ingår i: Asia-Pacific Microwave Conference Proceedings, APMC (APMC 2011 ;Melbourne, VIC; 5 - 8 December 2011). - 9780858259744 ; , s. 1642-1645
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Konferensbidrag (refereegranskat)abstract
- SiC Schottky diode varactors have been designed for use in tunable microwave power circuits. Epitaxial growth results show excellent material uniformity with low access layer sheet resistances. Two types of device layouts have been evaluated. Island type layouts reduce the parasitic series resistance by 50-60% compared to typical finger layouts. The Q-factors of downscaled island devices are approaching the intrinsic material performance, but are limited by an increasing parasitic parallel capacitance.
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| 3. |
- Andersson, Christer M, et al.
(författare)
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A SiC Varactor With Large Effective Tuning Range for Microwave Power Applications
- 2011
-
Ingår i: IEEE ELECTRON DEVICE LETTERS. - : IEEE Institute of Electrical and Electronics. - 0741-3106. ; 32:6, s. 788-790
-
Tidskriftsartikel (refereegranskat)abstract
- SiC Schottky diode varactors have been fabricated for use in microwave power applications, specifically the dynamic load modulation of power amplifiers. A custom doping profile has been employed to spread the C(V) over a large bias voltage range, thereby increasing the effective tuning range under large voltage swing conditions. The small-signal tuning range is approximately six, and punch through is reached at a bias voltage of -60 V, while the breakdown voltage is on the order of -160 V. An interdigitated layout is utilized together with a self-aligned Schottky anode etch process to improve the Q-factor at 2 GHz, which is 20 at zero bias and approximately 160 at punch through.
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| 4. |
- Andersson Grönlund, Marita, 1959-, et al.
(författare)
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Ophthalmologic involvement in Leigh syndrome
- 2017
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Ingår i: Acta Ophthalmologica. - : John Wiley & Sons. - 1755-375X .- 1755-3768. ; 95:1
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Andersson Grönlund, Marita, 1959-, et al.
(författare)
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Ophthalmological findings in children and young adults with genetically verified mitochondrial disease
- 2010
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Ingår i: British Journal of Ophthalmology. - : BMJ Publishing Group Ltd. - 0007-1161 .- 1468-2079. ; 94:1, s. 121-127
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To describe ophthalmological phenotypes in patients with mitochondrial disease and known genotypes.METHODS: A retrospective study was performed on 59 patients (29 male, 30 female) with a mean age of 11.8 years who had mitochondrial disease with known DNA mutations. Fifty-seven of the 59 subjects underwent a detailed ophthalmological examination including visual acuity (VA), eye motility, refraction, slit-lamp examination, ophthalmoscopy and, in almost one-half of the cases, a full-field electroretinogram (ERG).RESULTS: Forty-six (81%) of the patients had one or more ophthalmological findings such as ptosis (n = 16), reduced eye motility (n = 22) including severe external ophthalmoplegia (n = 9), strabismus (n = 4), nystagmus (n = 9), low VA (n = 21), refractive errors (n = 26), photophobia (n = 4), and partial or total optic atrophy (n = 25). Pigmentation in the macula and/or periphery was noted in 16 patients. In 10/27 investigated individuals with full field ERG, retinal dystrophy was recorded in six different genotypes representing Kearns-Sayre syndrome (n = 5), Leigh syndrome (n = 1), Mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) (n = 1), Myoclonus epilepsy with red ragged fibres (MERRF) (n = 1), Leber hereditary optic neuropathy (n = 1) and mitochondrial myopathy (n = 1).CONCLUSION: The results show that a majority of patients with mitochondrial disorders have ophthalmological abnormalities. We recommend that an ophthalmological examination, including ERG, be performed on all children and adolescents who are suspected of having a mitochondrial disease.
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| 6. |
- Andersson, Jan, et al.
(författare)
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Trafiksäkerhetspåverkan vid omkörning av 30-metersfordon
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Trafikverket överväger att tillåta längre och tyngre fordon på vägarna förutsatt att de inte påverkar trafiksäkerheten negativt. Syftet med studien var att undersöka säkerhetseffekten av fordonslängd, speciellt med avseende på olycksrisken vid omkörningar. Intervjuade förare av en 30-meters timmerbil hade inte upplevt de farhågor som förare av normallånga lastbilar uttryckt i samband med trånga rondeller och korsningar, men de nämner betydelsen av stödjande åkeri, arbetsmiljö och fordonsutrustning. En simulatorstudie studerade bilförares omkörningar av ett 30- och ett 18,75-metersfordon på en 2+1-väg i situationen då två körfält går ihop till ett. Tidluckan till ett återstående körfält var i genomsnitt 0,2 s (sign.) kortare efter omkörningar av 30-metersfordonet i situationer då bakänden var i samma relativa position som för 18,75-metersfordonet vid början av omkörningen. En fältstudie analyserade videoinspelade omkörningar av en 30- och en 24-meters timmerbil på en 2+1-väg och en tvåfältig väg. Ingen signifikant skillnad i tidluckor kunde påvisas mellan omkörningar av de två fordonen för någon av vägtyperna. Det senare resultatet ska dock tolkas med försiktighet på grund av ojämnt distribuerad data som insamlats under specifika förhållanden. Slutsatserna är att det finns en liten tendens till negativ säkerhetseffekt vid omkörningar av längre fordon, och att fler fältstudier är nödvändiga.
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| 7. |
- Andersson, Niklas, 1970, et al.
(författare)
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Drug-induced prevention of gastrectomy- and ovariectomy-induced osteopaenia in the young female rat.
- 2002
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Ingår i: The Journal of endocrinology. - : Bioscientifica. - 0022-0795 .- 1479-6805. ; 175:3, s. 695-703
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Tidskriftsartikel (refereegranskat)abstract
- Both ovariectomy (Ovx) and gastrectomy (Gx) induce osteopaenia in rats and humans. While the effect of Ovx has been ascribed to oestrogen deficiency, the underlying mechanism behind Gx is poorly understood. Alendronate, oestrogen and parathyroid hormone (PTH) are known to prevent the osteopaenia induced by Ovx in rats. The purpose of the present study was to determine whether alendronate, oestrogen or PTH could also prevent Gx-evoked osteopaenia. Rats were Ovx-, Gx-, or were sham-operated (Sham) and were then treated with alendronate (50 micro g/kg/day), oestrogen (10 micro g/kg/day) or PTH(1-84) (75 micro g/kg/day) for eight weeks. At sacrifice, serum PTH was unaffected by surgery (Ovx, 64+/-8 pg/ml; Gx, 75+/-13 pg/ml; Sham, 58+/-11 pg/ml). The bone mineral density (BMD) of the fifth lumbar vertebra (L5) was analysed. Ovx and Gx reduced the BMD (ash weight/Volume) of the L5 by 15+/-4% and 22+/-3% respectively. Trabecular BMD and the cortical bone mineral content (BMC) of the femur were assessed using peripheral computed tomography. Both Ovx and Gx markedly reduced trabecular BMD in the metaphyseal area of the distal femur (Ovx, -37+/-7%; Gx, -49+/-7%). The cortical BMC of the femur was only slightly reduced. Alendronate prevented trabecular bone loss after both Ovx and Gx, while oestrogen and PTH prevented trabecular bone loss after Ovx but not after Gx. In conclusion, the bisphosphonate alendronate prevented both Ovx- and Gx-induced trabecular bone loss. In contrast, PTH and oestrogen prevented Ovx-induced but not Gx-induced trabecular bone loss, suggesting that the mechanism behind the trabecular bone loss in Ovx rats differs from that in Gx rats. The results support the notion that the mechanism of action for the bone-sparing effect of these drugs differs. The ability of alendronate, and probably also other bisphosphonates, to prevent Gx-evoked osteopaenia in the rat might be of potential clinical interest when dealing with post-Gx osteopaenia in humans.
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| 8. |
- Andersson, Niklas, et al.
(författare)
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Methodology for fast development of digital solutions in integrated continuous downstream processing
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Ingår i: Biotechnology and Bioengineering. - 0006-3592.
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Tidskriftsartikel (refereegranskat)abstract
- The methodology for production of biologics is going through a paradigm shift from batch-wise operation to continuous production. Lot of efforts are focused on integration, intensification, and continuous operation for decreased foot-print, material, equipment, and increased productivity and product quality. These integrated continuous processes with on-line analytics become complex processes, which requires automation, monitoring, and control of the operation, even unmanned or remote, which means bioprocesses with high level of automation or even autonomous capabilities. The development of these digital solutions becomes an important part of the process development and needs to be assessed early in the development chain. This work discusses a platform that allows fast development, advanced studies, and validation of digital solutions for integrated continuous downstream processes. It uses an open, flexible, and extendable real-time supervisory controller, called Orbit, developed in Python. Orbit makes it possible to communicate with a set of different physical setups and on the same time perform real-time execution. Integrated continuous processing often implies parallel operation of several setups and network of Orbit controllers makes it possible to synchronize complex process system. Data handling, storage, and analysis are important properties for handling heterogeneous and asynchronous data generated in complex downstream systems. Digital twin applications, such as advanced model-based and plant-wide monitoring and control, are exemplified using computational extensions in Orbit, exploiting data and models. Examples of novel digital solutions in integrated downstream processes are automatic operation parameter optimization, Kalman filter monitoring, and model-based batch-to-batch control.
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| 9. |
- Andersson, Niklas, et al.
(författare)
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Model-Based Comparison of Batch and Continuous Preparative Chromatography in the Separation of Rare Earth Elements
- 2014
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 53:42, s. 16485-16493
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Tidskriftsartikel (refereegranskat)abstract
- The demand for rare earth elements (REEs) is growing, while the future supply is uncertain. Their unique electronic characteristics make them irreplaceable, and the commercial value of pure fractions is high. A model-based simulation study is presented that compares batch chromatography with the twin-column MCSGP (multicolumn countercurrent solvent gradient purification) process for ion-exchange chromatography of the four-component system neodymium, samarium, europium, and gadolinium. The last three components are considered products with individual purity requirements of 99%. The twin-column process has been shown to be a good alternative to the batch process regarding modifier consumption and productivity since it enables internal recycling to achieve high purities. A new cut strategy for MCSGP is applied where subfractions are taken from each outlet. Two multiobjective optimizations with yield, solvent productivity, and productivity objectives show that the MCSGP process is a better alternative than batch chromatography.
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| 10. |
- Andersson, Niklas, et al.
(författare)
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Models and Implementation of a Dynamic Element Matching DAC
- 2003
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Ingår i: Analog Integrated Circuits and Signal Processing. - Netherlands : Springer. - 0925-1030 .- 1573-1979. ; 34:1, s. 7-16
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic element matching (DEM) techniques for digital-to-analog converters (DACs) has been suggested as a promising method to improve matching between the DAC''s reference levels. However, no work has so far taken the dynamic effects that limit the performance for higher frequenciesinto account. In this paper we present a model describing the dynamic properties of a DEM DAC and compare the simulated results with measurements of a 14-bit current-steering DEM DAC implemented in a 0.35-μm CMOS process. The measured data agrees well with the results predicted by the used model. It is also shown that the DEM technique does not necessarily increase the performance of a DAC when dynamic errors are dominating the achievable performance.
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