| 11. |
- Chen, Ming Zheng, et al.
(författare)
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Ray-Tracing and Physical-Optics Model for Planar Mikaelian Lens Antennas
- 2024
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Ingår i: IEEE Transactions on Antennas and Propagation. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-926X .- 1558-2221. ; 72:2, s. 1735-1744
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Tidskriftsartikel (refereegranskat)abstract
- This article proposes a ray-tracing and physical-optics (RT-PO) model that allows for an accurate and time-efficient evaluation of planar Mikaelian lens antennas implemented by parallel plate waveguides (PPWs). With an intrinsic flat shape and axis-symmetry of refractive-index distribution characteristics, the planar Mikaelian lens antennas are easy to fabricate and integrate into standard planar feeds. A numerical computation of the ray paths based on Snell's law describes the phase of the electric field in the lens aperture, while the ray-tube power conservation theory is employed to evaluate the amplitude. The field equivalence principle is then used to calculate the far-field of the lens antenna. The information on far-field directivity, gain, and dielectric efficiency is further obtained, considering a small loss in the dielectric materials. Our approach is validated by comparing the results of a particular Mikaelian lens antenna with those computed using a commercial full-wave simulator, demonstrating high accuracy and a significant reduction in computation resources and times.
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| 12. |
- Chen, Weimin, 1959-, et al.
(författare)
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Optical Detection of Cyclotron Resonance (ODCR) in GaNAs/GaAs Quantum Well Structures
- 2000
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Konferensbidrag (refereegranskat)abstract
- ODCR has been employed to study effective masses and carrier recombination in GaNAs/GaAs multi-quantum well (MQW) structures, prepared by MBE with the nitrogen composition up to 4.5 above GaAs bandgap excitation consists of the excitonic recombination within the GaNAs MQW, the band edge PL emissions from GaAs and a broad 0.8-eV PL of unknown origin. When monitoring these emissions under the above GaAs excitation, the ODCR spectrum is dominated by the electron and hole CR in GaAs, with effective mass values 0.07m0 and 0.5m_0, respectively. The ODCR mechanism is discussed in terms of hot carrier effects, resulting in a reduced carrier recombination in GaAs and an enhanced carrier trapping in the GaNAs MQW. Under resonant excitation of the GaNAs MQW only a broad ODCR signal can be observed corresponding to an effective mass value 0.1m_0, attributed to the electron CR in the GaNAs MQW, where a higher electron effective mass value and a much lower mobility are expected.
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| 13. |
- Chen, Xingru, et al.
(författare)
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Reuse in Contemporary Software Engineering Practices - An Exploratory Case Study in A Medium-sized Company
- 2022
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Ingår i: e-Informatica Software Engineering Journal. - : Wroclaw University of Technology. - 1897-7979 .- 2084-4840. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Software practice is evolving with changing technologies and practices such as InnerSource, DevOps, and microservices. It is important to investigate the impact of contemporary software engineering (SE) practices on software reuse.Aim: This study aims to characterize software reuse in contemporary SE practices and investigate its implications in terms of costs, benefits, challenges, and potential improvements in a medium-sized company.Method: We performed an exploratory case study by conducting interviews, group discussions, and reviewing company documentation to investigate software reuse in the context of contemporary SE practices in the case company.Results: The results indicate that the development for reuse in contemporary SE practices incurs additional coordination, among other costs. Development with reuse led to relatively fewer additional costs and resulted in several benefits such as better product quality and less development and delivery time. Ownership of reusable assets is challenging in contemporary SE practice. InnerSource practices may help mitigate the top perceived challenges: discoverability and ownership of the reusable assets, knowledge sharing and reuse measurement.Conclusion: Reuse in contemporary SE practices is not without additional costs and challenges. However, the practitioners perceive costs as investments that benefit the company in the long run.
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| 14. |
- Chen, ZQ, et al.
(författare)
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Pharmacokinetics of caroverine in the inner ear and its effects on cochlear function after systemic and local administrations in Guinea pigs
- 2003
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Ingår i: Audiology & neuro-otology. - : S. Karger AG. - 1420-3030. ; 8:1, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- Caroverine, an N-methyl-<i>D</i>-aspartate and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor antagonist, has been shown to protect the inner ear from excitotoxicity and to be effective in the treatment of cochlear synaptic tinnitus. Local administration of caroverine on the round window membrane (RWM) could be a more effective means of administration to avoid systemic side/adverse effects. The present study investigates the pharmacokinetics of caroverine in the perilymph, cerebrospinal fluid (CSF) and plasma following intravenous and local applications at different dosages. High-performance liquid chromatography was used to determine the drug concentrations. Our results show much higher caroverine concentrations in the perilymph with lower concentrations in CSF and plasma following local applications compared with systemic administration. Auditory brainstem responses were measured to evaluate the changes in auditory function. The effects on hearing were transient and fully reversible 24 h after local caroverine applications. The findings suggest that local application of caroverine on the RWM for the treatment of excitotoxicity-related inner ear diseases, such as tinnitus and noise-induced hearing loss, might be both safe and more efficacious while avoiding high blood and CSF caroverine levels seen with systemic administration.
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| 15. |
- Hoffmann, Friedrich M., et al.
(författare)
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Hydrogenation of carbon dioxide by water : alkali-promoted synthesis of formate
- 2010
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Ingår i: Journal of Physical Chemistry Letters. - : American Chemical Society (ACS). - 1948-7185. ; 1:14, s. 2130-2134
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Tidskriftsartikel (refereegranskat)abstract
- Conversion of carbon,dioxide utilizing protons from water decomposition is likely to provide a sustainable source of fuels and chemicals in the future. We present here a time-evolved infrared reflection absorption spectroscopy (IRAS) and temperature-programmed desorption (TPD) study of the reaction of CO2 + H2O in thin potassium layers. Reaction at temperatures below 200 K results in the hydrogenation of carbon dioxide to potassium formate. Thermal stability of the formate, together with its sequential transformation to oxalate and to carbonate, is monitored and discussed. The data of this model study suggest a dual promoter mechanism of the potassium: the activation of CO2 and the dissociation of water. Reaction at temperatures above 200 K, in contrast, is characterized by the absence of formate and the direct reaction of CO2 to oxalate, due to a drastic reduction of the sticking coefficient of water at higher temperatures
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| 16. |
- Jerkeman, Matilda, et al.
(författare)
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Trends in survival after cardiac arrest: a Swedish nationwide study over 30 years
- 2022
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645.
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Tidskriftsartikel (refereegranskat)abstract
- AimsTrends in characteristics, management, and survival in out-of-hospital cardiac arrest (OHCA) and in-hospital cardiac arrest (IHCA) were studied in the Swedish Cardiopulmonary Resuscitation Registry (SCRR). Methods and resultsThe SCRR was used to study 106 296 cases of OHCA (1990–2020) and 30 032 cases of IHCA (2004–20) in whom resuscitation was attempted. In OHCA, survival increased from 5.7% in 1990 to 10.1% in 2011 and remained unchanged thereafter. Odds ratios [ORs, 95% confidence interval (CI)] for survival in 2017–20 vs. 1990–93 were 2.17 (1.93–2.43) overall, 2.36 (2.07–2.71) for men, and 1.67 (1.34–2.10) for women. Survival increased for all aetiologies, except trauma, suffocation, and drowning. OR for cardiac aetiology in 2017–20 vs. 1990–93 was 0.45 (0.42–0.48). Bystander cardiopulmonary resuscitation increased from 30.9% to 82.2%. Shockable rhythm decreased from 39.5% in 1990 to 17.4% in 2020. Use of targeted temperature management decreased from 42.1% (2010) to 18.2% (2020). In IHCA, OR for survival in 2017–20 vs. 2004–07 was 1.18 (1.06–1.31), showing a non-linear trend with probability of survival increasing by 46.6% during 2011–20. Myocardial ischaemia or infarction as aetiology decreased during 2004–20 from 67.4% to 28.3% [OR 0.30 (0.27–0.34)]. Shockable rhythm decreased from 37.4% to 23.0% [OR 0.57 (0.51–0.64)]. Approximately 90% of survivors (IHCA and OHCA) had no or mild neurological sequelae. ConclusionSurvival increased 2.2-fold in OHCA during 1990–2020 but without any improvement in the final decade, and 1.2-fold in IHCA during 2004–20, with rapid improvement the last decade. Cardiac aetiology and shockable rhythms were halved. Neurological outcome has not improved.
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| 17. |
- Lynoe, N, et al.
(författare)
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How to reveal disguised paternalism
- 2010
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Ingår i: Medicine, health care, and philosophy. - : Springer Science and Business Media LLC. - 1572-8633 .- 1386-7423. ; 13:1, s. 59-65
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Tidskriftsartikel (refereegranskat)
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| 18. |
- Palla, Linda
(författare)
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Similarities and variation in preschool special education studies : An overview of main content themes in Nordic research
- 2020
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Ingår i: Early Child Development and Care. - : Taylor & Francis. - 0300-4430 .- 1476-8275. ; 190:5, s. 698-711
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Forskningsöversikt (refereegranskat)abstract
- This review aims to provide an overview of content in Nordic research between 2006–2014 in the field of special education in preschool. More specifically, this review identifies the similarities and variation in and between content in the research. A total of 31 studies were found to be relevant. A summative thematic content analysis was made. The review revealed five main content themes: ‘special education and children in preschool’; ‘inclusion and participation’; ‘relationships, interaction, and cooperation’; ‘special educators’; and ‘special education documentation’. The themes give a better understanding of what content areas are focused on in the field of research. The result of the review points towards a shift in research. This from mainly have focused on individual-based interventions, to have a clearer direction to issues involving occupational groups responsibilities and opportunities in creating a preschool for all children, and concerns related to conditions for inclusion in spatial, social, and educational ways.
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| 19. |
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| 20. |
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