| 1. |
- Azremi, A.A.H., et al.
(författare)
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On diversity performance of two-element coupling element based antenna structure for mobile terminal
- 2010
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Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010.
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Konferensbidrag (refereegranskat)abstract
- In wireless communication systems, multipath interference has a significant impact on system design and performance. Fast fading is caused by the coherent summation of one or more echoes from many reflection points reaching the receive antenna. Antenna diversity can be used to mitigate multipath fading. The main challenge of antenna diversity in practical application is the integration of multiple antennas on a small ground plane. Two-element antenna structure based on coupling element antenna concept for diversity application has been studied in previous work and it has shown to be feasible for low frequency diversity application with stable and low envelope correlation across wide frequency range. The studied structure has been tuned to be operating at 1600 MHz for measurement evaluation purpose. This paper presents an analysis of diversity performance of the structure in terms of efficiencies, envelope correlation, and apparent and effective diversity gains in isotropic (i.e. statistically uniform) propagation channel, using spherical near-field technique in an ideal line-of-sight environment (anechoic chamber) and inside reverberation chamber. The envelope correlation is less than 0.1 and the diversity gain is equal to 10.2 dB at 99% reliability level using selection combining technique across simulation and both measurement methods. The measurement techniques are compared to show how accurately the diversity performance of a mobile terminal antenna can be estimated.
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| 2. |
- Laitinen, Antti, et al.
(författare)
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A graphene resonator as an ultrasound detector for generalized Love waves in a polymer film with two level states
- 2019
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Ingår i: Journal of Physics D: Applied Physics. - : IOP Publishing. - 1361-6463 .- 0022-3727. ; 52:24
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated surface shear waves at 22 MHz in a 0.5 micron thick polymer film on a SiO2/Si substrate at low temperatures using suspended and non-suspended graphene as detectors. By tracking ultrasound modes detected by oscillations of a trilayer graphene membrane both in vacuum and in helium superfluid, we assign the resonances to surface shear modes, generalized Love waves, in the resist/silicon-substrate system loaded with gold. The propagation velocity of these shear modes displays a logarithmic temperature dependence below 1 K, which is characteristic for modification of the elastic properties of a disordered solid owing to a large density of two level state systems. For the dissipation of the shear mode, we find a striking logarithmic temperature dependence, which indicates a basic relation between the speed of the surface wave propagation and the mode dissipation.
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| 3. |
- Melillo, Nicola, et al.
(författare)
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Use of In Vivo Imaging and Physiologically-Based Kinetic Modelling to Predict Hepatic Transporter Mediated Drug–Drug Interactions in Rats
- 2023
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Ingår i: Pharmaceutics. - : MDPI AG. - 1999-4923. ; 15:3
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Tidskriftsartikel (refereegranskat)abstract
- Gadoxetate, a magnetic resonance imaging (MRI) contrast agent, is a substrate of organic-anion-transporting polypeptide 1B1 and multidrug resistance-associated protein 2. Six drugs, with varying degrees of transporter inhibition, were used to assess gadoxetate dynamic contrast enhanced MRI biomarkers for transporter inhibition in rats. Prospective prediction of changes in gadoxetate systemic and liver AUC (AUCR), resulting from transporter modulation, were performed by physiologically-based pharmacokinetic (PBPK) modelling. A tracer-kinetic model was used to estimate rate constants for hepatic uptake (khe), and biliary excretion (kbh). The observed median fold-decreases in gadoxetate liver AUC were 3.8- and 1.5-fold for ciclosporin and rifampicin, respectively. Ketoconazole unexpectedly decreased systemic and liver gadoxetate AUCs; the remaining drugs investigated (asunaprevir, bosentan, and pioglitazone) caused marginal changes. Ciclosporin decreased gadoxetate khe and kbh by 3.78 and 0.09 mL/min/mL, while decreases for rifampicin were 7.20 and 0.07 mL/min/mL, respectively. The relative decrease in khe (e.g., 96% for ciclosporin) was similar to PBPK-predicted inhibition of uptake (97–98%). PBPK modelling correctly predicted changes in gadoxetate systemic AUCR, whereas underprediction of decreases in liver AUCs was evident. The current study illustrates the modelling framework and integration of liver imaging data, PBPK, and tracer-kinetic models for prospective quantification of hepatic transporter-mediated DDI in humans.
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| 4. |
- Zhang, J., et al.
(författare)
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Characterization of small antennas for hearing aids by several measurement techniques
- 2010
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Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010.
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Konferensbidrag (refereegranskat)abstract
- Characteristics of electrically small loop antennas were measured by different techniques and the results were compared in-between. The techniques employed were: a single-probe spherical near-field technique, a multi-probe spherical near-field technique, a reverberation chamber, and a Wheeler cap technique. The results were compared with regard to the measurement accuracy, measurement speed, and applicability for characterization of small antennas in complex application environment.
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