| 131951. |
- Karandikar, Yogesh, 1982
(författare)
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Factorization of Gaussian Coupling Efficiency and algorithm to compute it
- 2012
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Ingår i: Proceedings of 6th European Conference on Antennas and Propagation, EuCAP 2012. Prague, 26-30 March 2012. - 9781457709180 ; , s. 868-872
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Konferensbidrag (refereegranskat)abstract
- Gaussian Coupling Efficiency (η G) quantifies the amount of radiated power getting coupled to fundamental gaussian beam mode. This paper focus on the computations of η G for antennas from their far-field data. The mathematical analysis presented in the paper shows that the term η G can be factorized into sub-efficiencies namely, BOR 1, spill over, polarization and BOR 1 to Gaussian Coupling. This analysis is based on the definition of Body of Revolution type of antennas (BOR). Based on the analysis, an algorithm is developed to compute η G of Antennas. This algorithm accepts the far-field data of antenna as input and computes the optimum values of Beam Waist ω( o) and it's location (z o) for maximized η G. The algorithm is verified using Smooth Conical Horn. The beam parameters (ω o & z o) of Conical Horn obtained from near field measurements agree well with the beam parameters obtained from the simulated far-field. The 44 Microstrip patch Array is studied using this analysis and found that η G 70% is feasible for 320-350 GHz bandwidth.
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| 131952. |
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| 131953. |
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| 131954. |
- Karandikar, Yogesh, 1982, et al.
(författare)
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Reduction of radiation from central exciting region of Eleven feed and pattern improvements for VLBI 2010 applications
- 2010
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Ingår i: EuCAP 2010 Fourth European Conference on Antennas and Propagation, Barcelona, 12-16 April 2010. - 9788476534724 ; , s. Art. no. 5505151-
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Konferensbidrag (refereegranskat)abstract
- Multiport, decade bandwidth Eleven feed for prime focus reflector is ongoing development for VLBI 2010 applications. Current version of this feed uses four differential lines used to excite the log-periodic arrays above ground plane. These excitation lines packaged in small central region referred as centre puck shows radiation from lines above 10GHz causing distortion in feed pattern. This paper focuses on these radiations from exciting structures and proposes new methods to efficiently excite log-periodic arrays of Eleven feed while minimizing the radiation losses.
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| 131955. |
- Karandikar, Yogesh, 1982, et al.
(författare)
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X- Ka dual band prime focus feed for satellite earth terminals
- 2009
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Ingår i: Eucap 2009, 3rd European Conference on Antennas and Propagation - 23-27 March 2009 in Berlin, Germany. - 9781424447534 ; , s. 3085-3089
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Konferensbidrag (refereegranskat)abstract
- In this paper we propose new technology for combining X and Ka band prime focus feed for use in satellite earth terminals with simultaneous transmit/receive in circular polarization and also with tracking opportunity. The paper discusses the electrical and mechanical design of Ka band choke horn integrated with X band Eleven feed formed by two parallel dipoles over ground plane. The simulated results show input reflection coefficient better than -15dB and feed patterns give aperture efficiency better than -3dB over X as well as Ka band for 50° half subtended angle of reflector.
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| 131956. |
- Karandyszowska, N, et al.
(författare)
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RISK FOR CONCOMITANT AUTOIMMUNITY IN PATIENTS WITH ANTIPHOSPHOLIPID SYNDROME; A SWEDISH COHORT STUDY
- 2021
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Ingår i: ANNALS OF THE RHEUMATIC DISEASES. - : BMJ. - 0003-4967 .- 1468-2060. ; 80, s. 1184-1184
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In patients with the antiphospholipid syndrome (APS), concomitant systemic autoimmune rheumatic diseases (SARD) are common and often associated with more disease associated damage.Less is known about the prevalence of non-rheumatic autoimmune diseases (NRAID) in patients with APS.Objectives:To evaluate the incidence and prevalence of concomitant autoimmune diseases (AID) in a cohort of APS patients. The risk of AID was also evaluated with respect to the antiphospholipid antibodies (aPL) profiles.Methods:This retrospective cohort study comprises consecutive patients identified with APS through review of electronic medical records at Karolinska University Hospital, Sweden between 2014 and 2020. Exclusion criteria were misdiagnosis and age <18. Descriptive statistics was used for baseline data and multivariable Cox proportional hazard regression analysis to investigate the risk factors to develop new onset AID. Ethical approval was obtained from the Swedish Ethical Review Authority (2020-02333).Results:Of 271 included patients, 66% were women and the median age at diagnosis of APS was 43 years (IQR 31–55). At inclusion, 130 (48%) patients presented with other AID; 101 (37%) of them had a concomitant SARD while 54 (19%) had a NRAID. Systemic lupus erythematosus (SLE) was the most frequent in 30% of patients, followed by autoimmune thyroid disease (ATD) in 10% of patients.In addition, 35 (13%) APS-patients developed AID during the study period, corresponding to an incidence rate of 28.4 (95% CI; 19.3-40.3) per 1.000 person-years with mean time at risk of 4 (±2) years. Twenty-one (8%) patients developed a SARD and further 14 (5%) were diagnosed with a NRAID.The cumulative incidence for AID was significantly higher in patients with high titers of IgG aPL. Patients that developed SARD had significantly higher median titers of a-β2GPI IgG isotype, p=0.05. In the NRAID group, median a-β2GPI and aCL IgG isotypes were significantly increased, p=0.02 and p=0.04, respectively. The hazard ratio to develop diagnosis of AID was significantly increased in patients with high titers of the IgG isotype aPL (HR 2.4 95% CI; 1.1-5.3). Obstetric APS manifestations were associated with a significantly increased hazard ratio of 2.8 (95% CI; 1.1-7.7) to develop SARD, and also trendwise for AID, as a compound variable.During the study period, 52 patients had at least one new APS manifestation, as defined by the Sydney criteria (1). In comparison to patients without new manifestations, these patients had significantly higher median titers of aPL of the IgG isotype, and concomitant AID at first visit (p=0.01, p=0.02, respectively).Conclusion:APS patients are at high risk to develop other AID, and APS patients with concomitant AID had an increased risk to develop new clinical APS manifestations. These findings might be helpful when considering risk stratification and alternate treatment options in this patient group.References:[1]Miyakis S, Lockshin MD, Atsumi T et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost 2006; 4: 295–306.Acknowledgements:I have no acknowledgements to declare.Disclosure of Interests:None declared
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| 131957. |
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| 131958. |
- Karannagoda, Kesara, et al.
(författare)
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Nebula, a Gamification Framework for a High-quality Online Learning Experience
- 2023
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Ingår i: ICERI2023 Proceedings. - Sevilla, Spain : The International Academy of Technology, Education and Development. - 9788409559428 ; , s. 11-20
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Konferensbidrag (refereegranskat)abstract
- Gamification has been presented as an interesting concept for reinforcing teaching and learning in virtual learning environments. From this new emerging research field, several studies report on the promising potential of gamified education, but also on pitfalls to avoid. At the same time as there have been discussions on the lack of motivation in higher education, electronic sports (eSports) have increased in popularity. There are many research studies on gamification or eSports, but less research has been conducted on the combination of the two. This study has the aim of describing and discussing the Nebula framework for gamified virtual learning environments. Nebula is a framework that has been built on top of two components: course criteria, and gamified environment. Course criteria suggest instructors a specific set of methods to arrange course content in a particular way to produce a course module. Later on, the course module can be hosted in a gamified environment and referred by students. The gamified environment contains a set of artifacts that can create a dopamine-driven feedback loop on students to increase their engagement. Nebula framework has a very robust and structured assessment model in place. The personalized quiz system seems like a great way to ensure that users are being tested on content that is relevant to their individual needs and knowledge levels. The hidden rank system is also an interesting concept, as it can motivate users to keep striving to improve their rankings without feeling like they are being directly compared to others. This can be especially helpful for learners who may feel discouraged if they see others with higher rankings. The seasons and rating recalibration subsystems are also important components of the Nebula framework, as they can help to ensure that the ratings are accurate and reflective of the current skill levels of users. By periodically recalibrating the ratings, the platform can maintain a consistent level of quality and competitiveness. The assessment model and the ranking system of Nebula framework are well thought out and designed to provide a high-quality learning experience for users. In conclusion, gamification and eSports are emerging as promising fields for improving teaching and learning in virtual environments. The Nebula framework is a notable example of a gamified educational platform that leverages effective course design and gamification techniques to enhance student engagement and motivation. The framework's personalized quiz system, hidden rank system, and seasonal rating recalibration subsystems contribute to a strong and specific assessment model that maintains a consistent level of quality and competitiveness on the platform. Overall, the Nebula framework provides a well-designed and effective learning experience that holds potential for further development and research in the intersection of gamification and eSports. Future research should assess the effectiveness of this framework in improving student engagement, motivation, and learning outcomes in virtual environments.
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| 131959. |
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| 131960. |
- Karantininis, Konstantinos, et al.
(författare)
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Are there Financial Benefits to Join RoSCAs? Empirical evidence from Equb in Ethiopia
- 2012
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Ingår i: Procedia economics and finance. - 2212-5671. ; 1, s. 229-238
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Konferensbidrag (refereegranskat)abstract
- Rotating Savings and Credit Associations (RoSCA) are informal financial institutions serving the financial service needs of many people in the developing countries. Though some researchers recommend the transformation of those institutions into formal ones to create economic efficiency, there is not much research on why members join those institutions and what benefits they derive from them. By taking an empirical example of Ethiopian equb and focusing on the financial feasibility of financial viability of becoming a member in RoSCA, this study assesses why members join RoSCAs. The survey conducted revealed that the financial motives outweigh all other motives in large equbs while the social motives are most important for members of small equbs. Most large and medium size equb members choose equbs than other possible alternatives because it is less expensive and involves very small transaction cost, if any. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of the Organising Committee of ICOAE 2012
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