| 1. |
- Ardekani, Mehdi Niazi, et al.
(författare)
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Numerical study of the sedimentation of spheroidal particles
- 2016
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Ingår i: International Journal of Multiphase Flow. - : Elsevier BV. - 0301-9322 .- 1879-3533. ; 87, s. 16-34
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Tidskriftsartikel (refereegranskat)abstract
- The gravity-driven motion of-rigid particles in a viscous fluid is relevant in many natural and industrial processes, yet this has mainly been investigated for spherical particles. We therefore consider the sedimentation of non-spherical (spheroidal) isolated and particle pairs in a viscous fluid via numerical simulations using the Immersed Boundary Method. The simulations performed here show that the critical Galileo number for the onset of secondary motions decreases as the spheroid aspect ratio departs from 1. Above this critical threshold, oblate particles perform a zigzagging motion whereas prolate particles rotate around, the vertical axis while having their broad side facing the falling direction. Instabilities of the vortices in the wake follow when farther increasing the Galileo number. We also study the drafting kissing-tumbling associated with the settling of particle pairs. We find that the interaction time increases significantly for non-spherical particles and, more interestingly, spheroidal particles are attracted from larger lateral displacements. This has important implications for the estimation of collision kernels and can result its increasing clustering in suspensions of sedimenting spheroids.
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| 2. |
- Arvidsson, Yvonne, 1960, et al.
(författare)
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Cytotoxic Effects of Valproic Acid on Neuroendocrine Tumour Cells.
- 2016
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Ingår i: Neuroendocrinology. - : S. Karger AG. - 1423-0194 .- 0028-3835. ; 103:5, s. 578-591
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Tidskriftsartikel (refereegranskat)abstract
- Histone deacetylases (HDACs) modulate lysine acetylation on histones and are frequently deregulated in cancer. HDAC inhibitors with potent anti-tumour effects have been developed and are now being tested in clinical trials. The aim of this study was to investigate the effects of valproic acid (VPA), an inhibitor of class-I and class-IIa HDACs, on neuroendocrine tumour (NET) cell growth.
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| 3. |
- Arvidsson, Ylva, 1976-
(författare)
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Statlig styrning av svensk miljötillsyn : Som man frågar får man svar
- 2008
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Ingår i: Europarättslig tidskrift. - 1403-8722 .- 2002-3561. ; :2, s. 378-396
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Det är möjligt att analysera statlig styrning av svensk miljötillsyn på olika sätt. I artikeln presenteras en analysmodell som utgår från fyra olika delfrågor.Den första delfrågan är vad som kan motivera statlig styrning av svensk miljötillsyn. Delfråga två är vad som kan avses med sådan styrning, det vill säga hur företeelsen kan definieras. En tredje delfråga är hur statlig styrning av svensk miljötillsyn kan utformas och utövas. Den fjärde delfrågan handlar om hur konsekvenserna av styrningen kan bedömas.Det är en del av analysmodellen att dess fyra delfrågor undersöks utifrån tre olika perspektiv. Betydelsen av om förd argumentation utgår från ett demokratiskt, ekologiskt eller ekonomiskt perspektiv synliggörs. Som man frågar får man i regel svar.Tillämpningen av analysmodellen lyfter fram styrningsfrågans komplexitet och betydelsen av olika perspektiv. Den bidrar därmed till en fördjupad förståelse av statlig styrning av svensk miljötillsyn. Det blir enklare att förhålla sig till och utöva styrningen.EU-samarbetet och EG-rätten har ett stort och ökande inflytande på motiv, definitioner, tillämpning och konsekvensbedömningar avseende statlig styrning av svensk miljötillsyn. Styrningen är inte längre en enbart nationell fråga, utan den är i ökande grad en europeisk angelägenhet.
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| 4. |
- Arvidsson, Ylva, 1976-
(författare)
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The Precautionary Principle : Experiences from implementation into Swedish law
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The precautionary principle has evolved from the recognition that scientific certainty often comes too late to design effective responses for preventing environmental threats. In article 15 of the Rio Declaration it is defined as:Where there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost-effective measures to prevent environmental degradation.The precautionary principle is getting more widespread in international law. The next step is to increase and improve national implementation. Thus, the purpose of this thesis has been to analyse how the precautionary principle can be implemented into national environmental law, and what the main factors influencing the success of national precautionary actions and measures are.The main content of this thesis includes:· Analysis of how the precautionary principle has been implemented in Swedish environmental legislation and used for phasing out chlorofluorocarbons (CFCs) in Sweden.· An identification and analysis of main factors influencing the success of national actions and measures based upon the precautionary principle, including political and economic factors, factors related to research, information and technology, and legal and organisational factors.
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| 5. |
- Arvidsson, Åke, et al.
(författare)
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Analysis of user demand patterns and locality for YouTube traffic
- 2013
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Ingår i: In the Proceedings of the 25th International Teletraffic Congress (ITC).
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Konferensbidrag (refereegranskat)abstract
- Video content, of which YouTube is a major part, constitutes a large share of residential Internet traffic. In this paper, we analyse the user demand patterns for YouTube in two metropolitan access networks with more than 1 million requests over three consecutive weeks in the first network and more than 600,000 requests over four consecutive weeks in the second network. In particular we examine the existence of "local interest communities", i.e. the extent to which users living closer to each other tend to request the same content to a higher degree, and it is found that this applies to (i) the two networks themselves; (ii) regions within these networks (iii) households with regions and (iv) terminals within households. We also find that different types of access devices (PCs and handhelds) tend to form similar interest communities. It is also found that repeats are (i) "self-generating" in the sense that the more times a clip has been played, the higher the probability of playing it again, (ii) "long-lasting" in the sense that repeats can occur even after several days and (iii) "semiregular" in the sense that replays have a noticeable tendency to occur with relatively constant intervals. The implications of these findings are that the benefits from large groups of users in terms of caching gain may be exaggerated, since users are different depending on where they live and what equipment they use, and that high gains can be achieved in relatively small groups or even for individual users thanks to their relatively predictable behaviour.
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| 6. |
- Arvidsson, Åke, et al.
(författare)
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Congestion Control in Intelligent Networks for Real Time Performance and Profit Optimisation
- 1996
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Konferensbidrag (refereegranskat)abstract
- Current developments in technologies and markets stress the importance of exible and robust performance optimisation and congestion control. In intelligent networks, congestion control has traditionally taken a purely technical view and focused on pro- tecting individual nodes from harmful overloads. We take a profit oriented, network wide view and develop a congestion control mechanism to ensure real time performance under profit maximisation. Numerical studies in a simulator show that the proposed mechanism is robust and, in particular in overloaded states, provides a substantial improvement in comparison to conventional load control mechanisms.
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| 7. |
- Arvidsson, Åke
(författare)
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Distance Based Server Selection in 5G Networks
- 2022
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Konferensbidrag (refereegranskat)abstract
- Distance aware selection of servers and other net-worked resources is necessary to take full advantage of the 5G ecosystem, where the new radio and edge computing both contribute to significantly reduced latencies, but where propagation times to distant servers may add noticeable delays. The literature on server selection, and in particular on distance aware server selection, is, however, surprisingly thin. The few approaches we have come across are either relatively complex, based on continuous measurements, or both and not reflected in current standards. The present work therefore aims at simple but accurate mechanisms which build on and are backward compatible with present standards. We briefly describe the existing alternatives for distance aware selection as reflected in the standards, and propose include location information in server URLs such that distances can be explicitly calculated and evaluated by selecting entities. Moreover, we present three distinct and simple approaches to encode locations, two of which advantageously can be combined. The performance of the methods are then subject to a comprehensive performance evaluation where a large number of varied scenarios are considered. The results reveal that simple geographical coordinates should be restricted to very dense networks (typically networks which form full meshes) whereas a combination of the other approaches work well in other networks (in our case networks based on trees, stars or loops). Contrary to earlier proposals, our proposals consistently provide upper bounds on distances which eliminates the uncertainties that surrounds approximate solutions.
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| 8. |
- Arvidsson, Åke, et al.
(författare)
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Simple and Accurate Forecasting of the Market for Cellular Mobile Services
- 2007
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Ingår i: Managing Traffic Performance in Converged Networks. - Berlin : Springer. - 9783540729891
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Bokkapitel (refereegranskat)abstract
- We consider the problems of explaining and forecasting the penetration and the traffic in cellular mobile networks. To this end, we create two regression models, viz. one to predict the penetration from service charges and network effects and another one to predict the traffic from service charges and diffusion and adoption effects. The results of the models can also be combined to compute the likely evolutions of essential characteristics such as Minutes of Use (MoU), Average Revenue per User (ARPU) and total revenue. Applying the models to 26 markets throughout the world we show that they perform very well. Noting the significant qualitative differences between these markets, we conclude that the model has some universality in that the results are comparable for all of them.
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| 9. |
- Atwine, Fortunate, et al.
(författare)
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Health professionals' knowledge and attitudes to healthcare-seeking practices and complementary alternative medicine usage in Ugandans with diabetes : a cross-sectional survey
- 2017
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Ingår i: Pan African Medical Journal. - : AFRICAN FIELD EPIDEMIOLOGY NETWORK-AFENET. - 1937-8688. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Healthcare-seeking behaviour among persons with diabetes has been investigated to a limited extent, and not from professionals' perspective. The aim of the study was to describe healthcare professionals' knowledge, attitudes and practice concerning healthcare-seeking behaviour and the use of complementary and alternative medicine among persons with diabetes. Methods: A cross-sectional, self-administered questionnaire was conducted in western Uganda. Nurses, midwives or nurse assistants 72.2%, physicians 12% and clinical officers 10% volunteered to participate in the study with a total 108 (93% response rate) response rate. Descriptive statistics were used to analyse data with frequencies, percentages and summarized in tables. Results: Most of the healthcare providers perceived more uneducated people to be at risk of developing complications related to diabetes (66.7%) and that most of the patients with diabetes were not knowledgeable about signs and symptoms of diabetes before being diagnosed (75.9%). The main reasons inducing persons with diabetes to seek care outside the health care sector were reported to be seeking a cure for the condition, influence from the popular sector, the accessibility of the place and signs of complications of diabetes related to poor glycaemic control. Healthcare providers had relatively positive attitudes towards using complementary and alternative medicine. Conclusion: Insufficient knowledge about diabetes, compromised healthcare-seeking practices including drug procurement for diabetes seem to be barriers to diabetes management. Patients were thus reported to be burdened with co-morbidities of complications of diabetes related to poor glycaemic control.
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| 10. |
- Atwood, C., et al.
(författare)
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Incidence of EMS-treated out-of-hospital cardiac arrest in Europe
- 2005
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Ingår i: Resuscitation. - : Elsevier Ireland Ltd. - 0300-9572 .- 1873-1570. ; 67:1, s. 75-80
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The potential impact of efforts in Europe to improve survival from out-of-hospital cardiac arrest is unclear, in part, because estimates of incidence and survival are uncertain. The aim of the investigation was to determine a representative European incidence and survival from cardiac arrest in all-rhythms and in ventricular fibrillation treated by the emergency medical services (EMS). METHODS AND RESULTS: We used Medline to identify peer-reviewed articles published between 1 January 1980 and 30 June 2004 that reported a European community's EMS cardiac arrest experience. Inclusion criteria required the study to include at least 25 cases, report of the total number of all-rhythm and/or ventricular fibrillation arrests, and information about population size and study duration. The incidence was computed by dividing the total number of events by the product of the community's population and the study duration. Reports from 37 communities met the inclusion criteria. A total of 18,105 all-rhythm EMS-treated cardiac arrests occurred during 48 million person-years of observation, resulting in an overall incidence for all-rhythm arrests of 37.72 per 100,000 person-years. Incidence of ventricular fibrillation arrest was 16.84 per 100,000 person-years. Survival was 10.7% for all-rhythm and 21.2% for ventricular fibrillation cardiac arrest. Applying these results to the European population, approximately, 275,000 persons would experience, all-rhythm cardiac arrest treated by the EMS with 29,000 persons surviving to hospital discharge. CONCLUSION: The results provide a framework to assess opportunities and limitations of EMS care with regard to the public health burden of cardiac arrest in Europe.
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