| 1. |
- Hasselquist, David, et al.
(författare)
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Longitudinal Analysis of Wildcard Certificates in the WebPKI
- 2023
-
Ingår i: 2023 IFIP NETWORKING CONFERENCE, IFIP NETWORKING. - : IEEE. - 9783903176577 - 9798350339383
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Konferensbidrag (refereegranskat)abstract
- The use of wildcard certificates and multi-domain certificates can impact how sensitive a certificate is to attacks and how many (sub)domains and machines may be impacted if a private key is compromised. Unfortunately, there are no globally agreed-upon best practices for these certificate types and the recommendations have changed many times over the years. In this paper, we present a 10-year longitudinal analysis of the usage of wildcard certificates and multi-domain certificates on the internet. Our analysis captures and highlights substantial differences in the heterogenous wildcard and multi-domain certificate practices. The results also show that there are several ways that CAs and domain owners have chosen to improve their practices, with many appearing to reduce the number of domains (and subdomains) for which each certificate is responsible.
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| 2. |
- Hasselquist, David, et al.
(författare)
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Now is the Time: Scalable and Cloud-supported Audio Conferencing using End-to-End Homomorphic Encryption
- 2023
-
Ingår i: PROCEEDINGS OF THE 2023 CLOUD COMPUTING SECURITY WORKSHOP, CCSW 2023. - : ASSOC COMPUTING MACHINERY. - 9798400702594 ; , s. 41-53
-
Konferensbidrag (refereegranskat)abstract
- Homomorphic encryption (HE) allows computations on encrypted data, leaking neither the input nor the computational output. While the method has historically been infeasible to use in practice, due to recent advancements, HE has started to be applied in real-world applications. Motivated by the possibility of outsourcing heavy computations to the cloud and still maintaining end-to-end security, in this paper, we use HE to design a basic audio conferencing application and demonstrate that our design approach (including some advanced features) is both practical and scalable. First, by homomorphically mixing encrypted audio in an untrusted, honest-but-curious server, we demonstrate the practical use of HE in audio communication. Second, by using multiplication operations, we go beyond the purely additive audio mixing and implement advanced example features capable of handling server-side mute and breakout rooms without the cloud server being able to extract sensitive user-specific metadata. Whereas the encryption and decryption times are shown to be magnitudes slower than generic AES encryption and roughly ten times slower than Signal's AES implementation, our solution approach is scalable and achieves end-to-end encryption while keeping performance well within the bounds of practical use. Third, besides studying the performance aspects, we also objectively evaluate the perceived audio quality, demonstrating that this approach also achieves excellent audio quality. Finally, our comprehensive evaluation and empirical findings provide valuable insights into the tradeoffs between HE schemes, their security configurations, and audio parameters. Combined, our results demonstrate that audio mixing using HE (including advanced features) now can be made both practical and scalable.
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| 3. |
- Hasselquist, David, et al.
(författare)
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Twitch Chat Fingerprinting
- 2022
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Ingår i: Proc. IFIP Network Traffic Measurement and Analysis Conference (TMA) 2022.
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Konferensbidrag (refereegranskat)abstract
- The streaming content that we choose to watch canreveal much about our thoughts, opinions, and interests. Anadversary capable of determining what users watch thereforepresents a significant privacy threat. In this paper, we presentand evaluate the first fingerprinting attack on Twitch that allowsviewers of individual live streams to be identified despite thetraffic being encrypted. The attack targets the traffic patternsassociated with chat messages associated with each stream. Ourresults show that high accuracy can be achieved by eavesdroppingonly for a short time (e.g., 90 seconds) and that the accuracy canbe increased even further by interacting with the stream. We alsotake a closer look at how the accuracy and activity level differbetween different Twitch channels and provide insights into theaccuracy that attackers using different strategies for selectingtarget channels may have. Finally, we study countermeasures toprotect against such attacks and demonstrate that the naive use ofVPN is not enough. We instead present countermeasures alteringpacket timing and sizes. Our large-scale evaluation of differentcountermeasures provides important insights that help both thestreaming providers and users better protect their privacy.
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| 4. |
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| 5. |
- Aaro, Gustav, 1995-, et al.
(författare)
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Toolset for Run-time Dataset Collection of Deep-scene Information
- 2020
-
Ingår i: Symposium on Modelling, Analysis, and Simulation of Computer and Telecommunication Systems (MASCOTS). - Cham : Springer. - 9783030681098 ; , s. 224-236
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Konferensbidrag (refereegranskat)abstract
- Virtual reality (VR) provides many exciting new application opportunities, but also present new challenges. In contrast to 360° videos that only allow a user to select its viewing direction, in fully immersive VR, users can also move around and interact with objects in the virtual world. To most effectively deliver such services it is therefore important to understand how users move around in relation to such objects. In this paper, we present a methodology and software tool for generating run-time datasets capturing a user’s interactions with such 3D environments, evaluate and compare different object identification methods that we implement within the tool, and use datasets collected with the tool to demonstrate example uses. The tool was developed in Unity, easily integrates with existing Unity applications through the use of periodic calls that extracts information about the environment using different ray-casting methods. The software tool and example datasets are made available with this paper.
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| 6. |
- Abdel-Halim, Adam, et al.
(författare)
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Temporal Analysis of X.509 Revocations and their Statuses
- 2022
-
Ingår i: 7TH IEEE EUROPEAN SYMPOSIUM ON SECURITY AND PRIVACY WORKSHOPS (EUROS&PW 2022). - : IEEE. - 9781665495608 ; , s. 258-265
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Konferensbidrag (refereegranskat)abstract
- Despite the X509 public key infrastructure (PKI) being essential for ensuring the trust we place in our communication with web servers, the revocation of the trust placed in individual X509 certificates is neither transparent nor well-studied, leaving many unanswered questions. In this paper, we present a temporal analysis of 36 million certificates, whose revocation statuses we followed for 120 days since first being issued. We characterize the revocation rates of different certificate authorities (CAs) and how the rates change over the lifetime of the certificates. We identify and discuss several instances where the status changes from "revoked" to "good", "unauthorized" or "unknown", respectively, before the certificates expiry. This complements prior work that has observed such inconsistencies in some CAs behavior after expiry but also highlight a potentially more severe problem. Our results highlight heterogeneous revocation practices among the CAs.
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| 7. |
- Acemoglu, Daron, et al.
(författare)
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Harmonic influence in largescale networks
- 2014. - 3
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Ingår i: ACM SIGMETRICS Performance Evaluation Review. - : Association for Computing Machinery (ACM). - 0163-5999. - 9781450327893 ; 42, s. 24-24
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Konferensbidrag (refereegranskat)
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| 8. |
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| 9. |
- Ahlén, Niklas, 1970-
(författare)
-
Carbothermal synthesis of transition metal carbide and carbonitride whiskers via a Vapour-Liquid-Solid (VLS) growth mechanism
- 1999
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A route for the synthesis of TiC, TiCyN1-y, TaxTi1-xC and TaxTi1-xCyN1-y whiskers via a carbothermal Vapour-Liquid-Solid (VLS) growth mechanism, yielding 70-90 vol.% whiskers, has been established. The whiskers were uniform in diameter (0.3-0.6mm), and had a length of about 10-30mm. The starting materials consisted of TiO2 and/or Ta2O5, C, a catalyst metal (Ni or Fe) and NaCl. Carbon was added to reduce the oxides, and NaCl to provide chlorine in the formation of TiClx(g) and TaOxCly(g) species. The overall chemical reaction is a straightforward carbothermal reduction process. The optimum synthesis temperature was found to be 1250°C for TiCyN1-y, TaxTi1-xC and TaxTi1-xCyN1-y whisker, and 1400°C for TiC. The growth direction of the whiskers was found to be <100> for TaC and TaxTi1-xC and either <100> or <111> for TiC. Nitridation of TiC whiskers yielded TiCyN1-y whiskers with morphology and chemical composition different from those obtained by the carbothermal VLS growth mechanism. From oxidation studies it was found that TiC had the lowest oxidation resistance (onset temperature Ton=390°C) and that TaC had the highest (Ton=550°C). The oxidation onset temperature was found to increase with increasing x-value for both TaxTi1-xC and TaxTi1-xCyN1-y whiskers. Microscopy studies (SEM and TEM) showed that whiskers with a native diameter exceeding 0.3 mm split into two halves along their length when oxidised. It was found that the TiO2 particle size of oxidised TaxTi1-xC whiskers are markedly smaller than that obtained from oxidation of TiC whiskers, whereas the Ta2O5 particle size was the same as that observed for oxidised TaC whiskers.
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| 10. |
- Almquist, Mathias, et al.
(författare)
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The Prefetch Aggressiveness Tradeof in 360 degrees Video Streaming
- 2018
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Ingår i: PROCEEDINGS OF THE 9TH ACM MULTIMEDIA SYSTEMS CONFERENCE (MMSYS18). - New York, NY, USA : ASSOC COMPUTING MACHINERY. - 9781450351928 ; , s. 258-269
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Konferensbidrag (refereegranskat)abstract
- With 360 degrees video, only a limited fraction of the full view is displayed at each point in time. This has prompted the design of streaming delivery techniques that allow alternative playback qualities to be delivered for each candidate viewing direction. However, while prefetching based on the users expected viewing direction is best done close to playback deadlines, large buffers are needed to protect against shortfalls in future available bandwidth. This results in conflicting goals and an important prefetch aggressiveness tradeoff problem regarding how far ahead in time from the current playpoint prefetching should be done. This paper presents the first characterization of this tradeoff. The main contributions include an empirical characterization of head movement behavior based on data from viewing sessions of four different categories of 360 degrees video, an optimization-based comparison of the prefetch aggressiveness tradeoffs seen for these video categories, and a data-driven discussion of further optimizations, which include a novel system design that allows both tradeoff objectives to be targeted simultaneously. By qualitatively and quantitatively analyzing the above tradeoffs, we provide insights into how to best design tomorrows delivery systems for 360 degrees videos, allowing content providers to reduce bandwidth costs and improve users playback experiences.
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| 11. |
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| 12. |
- Andersson, Niklas, et al.
(författare)
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Parameter Selection in the Parameter Estimation of Grade Transitions in a Polyethylene Plant
- 2015
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Ingår i: Studies in Engineering and Technology. - : Redfame Publishing. - 2330-2038 .- 2330-2046. ; 3:1, s. 1-18
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Tidskriftsartikel (refereegranskat)abstract
- A polyethylene plant at Borealis AB is modelled in the Modelica language and considered for parameter estimations at grade transitions. Parameters have been estimated for both the steady-state and the dynamic case using the JModelica.org platform, which offers tools for steady-state parameter estimation and supports simulation with parameter sensitivies. The model contains 31 candidate parameters, giving a huge amount of possible parameter combinations. The best parameter sets have been chosen using a parameter-selection algorithm that identified parameter sets with poor numerical properties. The parameter-selection algorithm reduces the number of parameter sets that is necessary to explore. The steady-state differs from the dynamic case with respect to parameter selection. Validations of the parameter estimations in the dynamic case show a significant reduction in an objective value used to evaluate the quality of the solution from that of the nominal reference, where the nominal parameter values are used.
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| 13. |
- Arestrom, Erik, et al.
(författare)
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Early Online Classification of Encrypted Traffic Streams using Multi-fractal Features
- 2019
-
Ingår i: IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (IEEE INFOCOM 2019 WKSHPS). - : IEEE. - 9781728118789 ; , s. 84-89
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Konferensbidrag (refereegranskat)abstract
- Timely and accurate flow classification is important for identifying flows with different service requirements, optimized network management, and for helping network operators simultaneously operate networks at higher utilization while providing end users good quality of experience (QoE). With most services starting to use end-to-end encryption (HTTPS and QUIC), traditional Deep Packet Inspection (DPI) and port-based approaches are no longer applicable. Furthermore, most flow-level-based approaches ignore the complex non-linear characteristics of internet traffic (e.g., self similarity). To address this challenge, in this paper, we present and evaluate a classification framework that combines multi-fractal feature extraction based on time series data (which captures these non-linear characteristics), principal component analysis (PCA) based feature selection, and man-in-the-middle (MITM) based flow labeling. Our detailed evaluation shows that the method is able to quickly and effectively classify traffic belonging to the six most popular traffic types (video streaming, web browsing, social networking, audio communication, text communication, and bulk download) and to distinguish between video-on-demand (VoD) and live streaming sessions delivered from the same services. Our results show that good accuracy can be achieved with only information about the timing of the packets within a flow.
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| 14. |
- Arlitt, Martin, et al.
(författare)
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Characterizing Intelligence Gathering and Control on an Edge Network
- 2011
-
Ingår i: ACM Transactions on Internet Technology. - : ASSOC COMPUTING MACHINERY, 2 PENN PLAZA, STE 701, NEW YORK, NY 10121-0701 USA. - 1533-5399 .- 1557-6051. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- here is a continuous struggle for control of resources at every organization that is connected to the Internet. The local organization wishes to use its resources to achieve strategic goals. Some external entities seek direct control of these resources, for purposes such as spamming or launching denial-of-service attacks. Other external entities seek indirect control of assets (e. g., users, finances), but provide services in exchange for them. less thanbrgreater than less thanbrgreater thanUsing a year-long trace from an edge network, we examine what various external organizations know about one organization. We compare the types of information exposed by or to external organizations using either active (reconnaissance) or passive (surveillance) techniques. We also explore the direct and indirect control external entities have on local IT resources.
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| 15. |
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| 16. |
- Arlitt, Martin, et al.
(författare)
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Passive Crowd-based Monitoring of World Wide Web Infrastructure and its Performance
- 2012
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Ingår i: Proc. IEEE International Conference on Communications (ICC 2012). - : IEEE. - 9781457720529 - 9781457720512 ; , s. 2689-2694
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Konferensbidrag (refereegranskat)abstract
- The World Wide Web and the services it provides are continually evolving. Even for a single time instant, it is a complex task to methodologically determine the infrastructure over which these services are provided and the corresponding effect on user perceived performance. For such tasks, researchers typically rely on active measurements or large numbers of volunteer users. In this paper, we consider an alternative approach, which we refer to as passive crowd-based monitoring. More specifically, we use passively collected proxy logs from a global enterprise to observe differences in the quality of service (QoS) experienced by users on different continents. We also show how this technique can measure properties of the underlying infrastructures of different Web content providers. While some of these properties have been observed using active measurements, we are the first to show that many of these properties (such as location of servers) can be obtained using passive measurements of actual user activity. Passive crowd-based monitoring has the advantages that it does not add any overhead on Web infrastructure, it does not require any specific software on the clients, but still captures the performance and infrastructure observed by actual Web usage.
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| 17. |
- Arvanitaki, Antonia, et al.
(författare)
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Delay Performance of a Two-User Broadcast Channel with Security Constraints
- 2018
-
Ingår i: 2018 GLOBAL INFORMATION INFRASTRUCTURE AND NETWORKING SYMPOSIUM (GIIS). - : IEEE. - 9781538672723
-
Konferensbidrag (refereegranskat)abstract
- In this paper we consider the two-user broadcast channel with security constraints. We assume that one of the receivers has a secrecy constraint; i.e., its packets need to be kept secret from the other receiver. The receiver with secrecy constraint has full-duplex capability to transmit a jamming signal to increase its secrecy. We derive the average delay per packet and provide simulation and numerical results, where we compare different performance metrics for the cases when the legitimate receiver performs successive decoding and when both receivers treat interference as noise.
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| 18. |
- Arvanitaki, Antonia, 1991-, et al.
(författare)
-
Delay Performance of a Two-User Broadcast Channel with Security Constraints
- 2020
-
Ingår i: SN Computer Science. - : Springer. - 2661-8907 .- 2662-995X. ; 1:1
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we consider the two-user broadcast channel with security constraints. We assume that a source broadcasts packets to two receivers, and that one of them has secrecy constraints, i.e., its packets need to be kept secret from the other receiver. The receiver with secrecy constraint has full-duplex capability, allowing it to transmit a jamming signal to increase its secrecy. We derive the average delay per packet and provide simulations and numerical results, where we compare different performance metrics for the cases when both receivers treat interference as noise, when the legitimate receiver performs successive decoding, and when the eavesdropper performs successive decoding. The results show that successive decoding provides better average packet delay for the legitimate user. Furthermore, we define a new metric that characterizes the reduction on the success probability for the legitimate user that is caused by the secrecy constraint. The results show that secrecy poses a significant amount of packet delay for the legitimate receiver when either receiver performs successive decoding. We also formulate an optimization problem, wherein the throughput of the eavesdropper is maximized under delay and secrecy rate constraints at the legitimate receiver. We provide numerical results for the optimization problem, where we show the trade-off between the transmission power for the jamming and the throughput of the non-legitimate receiver. The results provide insights into how channel ordering and encoding differences can be exploited to improve performance under different interference conditions.
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| 19. |
- Arvanitaki, Antonia, et al.
(författare)
-
Performance analysis of congestion-aware secure broadcast channels
- 2021
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Ingår i: EURASIP Journal on Wireless Communications and Networking. - : Springer. - 1687-1472 .- 1687-1499. ; 2021:1
-
Tidskriftsartikel (refereegranskat)abstract
- Congestion-aware scheduling in case of downlink cellular communication has ignored the distribution of diverse content to different clients with heterogeneous secrecy requirements. Other possible application areas that encounter the preceding issue are secure offloading in mobile-edge computing, and vehicular communication. In this paper, we extend the work in Arvanitaki et al. (SN Comput Sci 1(1):53, 2019) by taking into consideration congestion and random access. Specifically, we study a two-user congestion-aware broadcast channel with heterogeneous traffic and different security requirements. We consider two randomized policies for selecting which packets to transmit, one is congestion-aware by taking into consideration the queue size, whereas the other one is congestion-agnostic. We analyse the throughput and the delay performance under two decoding schemes at the receivers, and provide insights into their relative security performance and into how congestion control at the queue holding confidential information can help decrease the average delay per packet. We show that the congestion-aware policy provides better delay, throughput, and secrecy performance for large arrival packet probabilities at the queue holding the confidential information. The derived results also take account of the self-interference caused at the receiver for whom confidential data is intended due to its full-duplex operation while jamming the communication at the other user. Finally, for two decoding schemes, we formulate our problems in terms of multi-objective optimization, which allows for finding a trade-off between the average packet delay for packets intended for the legitimate user and the throughput for the other user under congestion-aware policy.
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| 20. |
- Arvanitaki, Antonia, 1991-, et al.
(författare)
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Secrecy in Congestion-Aware Broadcast Channels
- 2021
-
Ingår i: Proc. Wireless Days Conference (WD) 2021. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781665425599 - 9781665425605
-
Konferensbidrag (refereegranskat)abstract
- Congestion-aware scheduling in the case of traditional downlink cellular communication has neglected the heterogeneity in terms of secrecy among different clients. In this paper, we study a two-user congestion-aware broadcast channel with heterogeneous traffic and different security requirements. The traffic with security requirements is intended for a legitimate user and it has bursty nature. The incoming packets are stored in a queue at the source. Furthermore, there is a second traffic flow intended for another user, it is delay tolerant and does not have secrecy constraints. The receiver which needs to be served with confidential data has full-duplex capabilities, and it can send a jamming signal to hinder eavesdropping of its data at the other user. We consider two randomized policies for selecting which packets to transmit, one is congestion-aware by taking into consideration the queue size, whereas the other one is non-congestion-aware. We analyse the throughput and the delay performance under two decoding schemes at the receivers and provide insights into their relative security performance and into how congestion control at the queue holding confidential information can help decrease the average delay per packet. We show that the two policies have the same secrecy performance for large random access probabilities. The derived results also take account of the self-interference caused at the receiver for whom confidential data is intended due to its full-duplex operation while jamming the communication at the other user.
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| 21. |
- Asplund Carlsson, Maj, 1948, et al.
(författare)
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Från görande till lärande och förståelse. En studie av lärares lärande inom estetik
- 2008
-
Ingår i: Nordisk Barnehageforskning. - 1890-9167. ; 1:1, s. 41-51
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this article is to analyze teachers’ changing ways of talking about children’s aesthetic learning in the early years as a result of a research and development project. With a point of departure in developmental and variation theory, a praxis oriented project was designed with the aim of finding out whether collaborative talk and meta-cognitive dialogues could contribute to children’s learning of music, dance and poetry. The participating teachers were offered in-service training in order to develop a new way of teaching and new ways of thinking about the curriculum and children’s learning. Interviews with the teachers were carried out at the beginning and the end of the project. The teachers’ learning was expressed in changed ways of talking about aesthetics and learning. From an emphasis on personality development and the teacher’s lack of expertise with the aesthetic subjects as an obstacle, the teachers expressed a view of having become more aware of the concept of learning objects in the aesthetics, of their own role as teachers in directing children’s attention and to listen to children. The teachers thus gained a new way of talking about themselves as teachers and about children’s learning within music, dance and poetry.
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| 22. |
- Bertmar, Sofia, et al.
(författare)
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Who's Most Targeted and Does My New Adblocker Really Help : A Profile-based Evaluation of Personalized Advertising
- 2021
-
Ingår i: Proc. ACM CCS Workshop on Privacy in the Electronic Society (ACM WPES @CCS). - New York, NY, USA : ACM Digital Library. - 9781450385275
-
Konferensbidrag (refereegranskat)abstract
- There is limited prior work studying how the ad personalization experienced by different users is impacted by the use of adblockers, geographic location, the user's persona, or what browser they use. To address this void, this paper presents a novel profile-based evaluation of the personalization experienced by carefully crafted user profiles. Our evaluation framework impersonates different users and captures how the personalization changes over time, how it changes when adding or removing an extension, and perhaps most importantly how the results differ depending on the profile's persona (e.g., interest, occupation, age, gender), geographic location (US East, US West, UK), what browser extension they use (none, AdBlock, AdBlock Plus, Ghostery, CatBlock), what browser they use (Chrome, Firefox), and whether they are logged in to their Google account. By comparing and contrasting observed differences we provide insights that help explain why some user groups may feel more targeted than others and why some people may feel even more targeted after having turned on their adblocker.
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| 23. |
- Bjohle, J, et al.
(författare)
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Serum thymidine kinase activity compared with CA 15-3 in locally advanced and metastatic breast cancer within a randomized trial
- 2013
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Ingår i: Breast Cancer Research and Treatment. - : Springer Verlag (Germany). - 0167-6806 .- 1573-7217. ; 139:3, s. 751-758
-
Tidskriftsartikel (refereegranskat)abstract
- The primary objective was to estimate serum thymidine kinase 1 (TK1) activity, reflecting total body cell proliferation rate including cancer cell proliferation, in women with loco regional inoperable or metastatic breast cancer participating in a prospective and randomized study. Secondary objectives were to analyze TK1 in relation to progression-free survival (PFS), overall survival (OS), therapy response and other tumour characteristics, including CA 15-3, widely used as a standard serum marker for disease progression. TK1 and CA 15-3 were analysed in 198 serum samples collected prospectively from women included in the randomized TEX trial between December 2002 and June 2007. TK1 activity was determined by the ELISA based DiviTum (TM) assay, and CA 15-3 analyses was generated with the electrochemiluminescence immunoassay Cobas Elecsys CA 15-3 II. High pre-treatment TK1 activity predicted shorter PFS (10 vs. 15 months p = 0.02) and OS (21 vs. 38 months, p andlt; 0.0001), respectively. After adjustment for age, metastatic site and study treatment TK1 showed a trend as predictor of PFS (p = 0.059) and was an independent prognostic factor for OS, (HR 1.81, 95 % confidence interval (CI) 1.26-2.61, p = 0.001). There was a trend of shortened OS for women with high CA 15-3 (p = 0.054) in univariate analysis, but not after adjustment for the above mentioned covariates. Both TK1 (p = 0.0011) and CA 15-3 (p = 0.0004) predicted response to treatment. There were statistically different distributions of TK1 and CA 15-3 in relation to the site of metastases. TK1 activity measured by DiviTum (TM) predicted therapy response, PFS and OS in loco regional inoperable or disseminated breast cancer. These results suggest that this factor is a useful serum marker. In the present material, a prognostic value of CA 15-3 could not be proven.
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| 24. |
- Boldt, Martin, et al.
(författare)
-
Preventing Privacy-Invasive Software using Online Reputations
- 2008
-
Konferensbidrag (refereegranskat)abstract
- Privacy-invasive software, loosely labeled spyware, is an increasingly common problem for today’s computer users, one to which there is no absolute cure. Most of the privacy-invasive software are positioned in a legal gray zone, as the user accepts the malicious behaviour when agreeing to the End User License Agreement. This paper proposes the use of a specialized reputation system to gather and share information regarding software behaviour between community users. A client application helps guide the user at the point of executing software on the local computer, displaying other users’ feedback about the expected behaviour of the software. We discuss important aspects to consider when constructing such a system, and propose possible solutions. Based on the observations made, we implemented a client/server based proof-of-concept tool, which allowed us to demonstrate how such a system would work. We also compare this solution to other, more conventional, protection methods such as anti-virus and anti-spyware software.
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| 25. |
- Borghol, Youmna, et al.
(författare)
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Characterizing and modelling popularity of user-generated videos
- 2011
-
Ingår i: Performance evaluation (Print). - : Elsevier. - 0166-5316 .- 1872-745X. ; 68:11, s. 1037-1055
-
Tidskriftsartikel (refereegranskat)abstract
- This paper develops a framework for studying the popularity dynamics of user-generated videos, presents a characterization of the popularity dynamics, and proposes a model that captures the key properties of these dynamics. We illustrate the biases that may be introduced in the analysis for some choices of the sampling technique used for collecting data; however, sampling from recently-uploaded videos provides a dataset that is seemingly unbiased. Using a dataset that tracks the views to a sample of recently-uploaded YouTube videos over the first eight months of their lifetime, we study the popularity dynamics. We find that the relative popularities of the videos within our dataset are highly non-stationary, owing primarily to large differences in the required time since upload until peak popularity is finally achieved, and secondly to popularity oscillation. We propose a model that can accurately capture the popularity dynamics of collections of recently-uploaded videos as they age, including key measures such as hot set churn statistics, and the evolution of the viewing rate and total views distributions over time.
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| 26. |
- Borghol, Youmna, et al.
(författare)
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The Untold Story of the Clones: Content-agnostic Factors that Impact YouTube Video Popularity
- 2012
-
Ingår i: Proc. ACM SIGKDD Conference on Knowledge Discovery and Data Mining (KDD) 2012. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450314626 ; , s. 1186-1194
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Konferensbidrag (refereegranskat)abstract
- Video dissemination through sites such as YouTube can have widespread impacts on opinions, thoughts, and cultures. Not all videos will reach the same popularity and have the same impact. Popularity differences arise not only because of differences in video content, but also because of other "content-agnostic" factors. The latter factors are of considerable interest but it has been difficult to accurately study them. For example, videos uploaded by users with large social networks may tend to be more popular because they tend to have more interesting content, not because social network size has a substantial direct impact on popularity.In this paper, we develop and apply a methodology that is able to accurately assess, both qualitatively and quantitatively, the impacts of various content-agnostic factors on video popularity. When controlling for video content, we observe a strong linear "rich-get-richer" behavior, with the total number of previous views as the most important factor except for very young videos. The second most important factor is found to be video age. We analyze a number of phenomena that may contribute to rich-get-richer, including the first-mover advantage, and search bias towards popular videos. For young videos we find that factors other than the total number of previous views, such as uploader characteristics and number of keywords, become relatively more important. Our findings also confirm that inaccurate conclusions can be reached when not controlling for content.
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| 27. |
- Borghol, Youmna, et al.
(författare)
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Toward Efficient On-demand Streaming with BitTorrent
- 2010
-
Ingår i: NETWORKING 2010. - Berlin, Heidelberg : Springer. - 9783642129629 - 3642129625 ; , s. 53-66
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Bokkapitel (refereegranskat)abstract
- This paper considers the problem of adapting the BitTorrent protocol for on-demand streaming. BitTorrent is a popular peer-to-peer file sharing protocol that efficiently accommodates a large number of requests for file downloads. Two components of the protocol, namely the Rarest-First piece selection policy and the Tit-for-Tat algorithm for peer selection, are acknowledged to contribute toward the protocol's efficiency with respect to time to download files and its resilience to freeriders. Rarest-First piece selection, however, does not augur well for on-demand streaming. In this paper, we present a new adaptive Window-based piece selection policy that achieves a balance between the system scalability provided by the Rarest-First algorithm and the necessity of In-Order pieces for seamless media playback. We also show that this simple modification to the piece selection policy allows the system to be efficient with respect to utilization of available upload capacity of participating peers, and does not break the Tit-for-Tat incentive scheme which provides resilience to freeriders.
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| 28. |
- Braegelmann, Johannes, et al.
(författare)
-
Pan-Cancer Analysis of the Mediator Complex Transcriptome Identifies CDK19 and CDK8 as Therapeutic Targets in Advanced Prostate Cancer
- 2017
-
Ingår i: Clinical Cancer Research. - : American Association for Cancer Research Inc.. - 1078-0432 .- 1557-3265. ; 23:7, s. 1829-1840
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: The Mediator complex is a multiprotein assembly, which serves as a hub for diverse signaling pathways to regulate gene expression. Because gene expression is frequently altered in cancer, a systematic understanding of the Mediator complex in malignancies could foster the development of novel targeted therapeutic approaches.Experimental Design: We performed a systematic deconvolution of the Mediator subunit expression profiles across 23 cancer entities (n = 8,568) using data from The Cancer Genome Atlas (TCGA). Prostate cancer-specific findings were validated in two publicly available gene expression cohorts and a large cohort of primary and advanced prostate cancer (n = 622) stained by immunohistochemistry. The role of CDK19 and CDK8 was evaluated by siRNA-mediated gene knockdown and inhibitor treatment in prostate cancer cell lines with functional assays and gene expression analysis by RNAseq.Results: Cluster analysis of TCGA expression data segregated tumor entities, indicating tumor-type-specific Mediator complex compositions. Only prostate cancerwasmarked by high expression of CDK19. In primary prostate cancer, CDK19 was associated with increased aggressiveness and shorter disease-free survival. During cancer progression, highest levels of CDK19 and of its paralog CDK8were present inmetastases. In vitro, inhibition ofCDK19 and CDK8 by knockdown or treatment with a selective CDK8/ CDK19 inhibitor significantly decreased migration and invasion.Conclusions: Our analysis revealed distinct transcriptional expression profiles of the Mediator complex across cancer entities indicating differential modes of transcriptional regulation. Moreover, it identified CDK19 and CDK8 to be specifically overexpressed during prostate cancer progression, highlighting their potential as novel therapeutic targets in advanced prostate cancer.
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| 29. |
- Bruhner, Carl Magnus, 1988-, et al.
(författare)
-
Bridging the Privacy Gap: Enhanced User Consent Mechanisms on the Web
- 2023
-
Ingår i: Proc. NDSS Workshop on Measurements, Attacks, and Defenses for the Web (MADWeb @NDSS). - Reston, VA : Internet Society. - 1891562878
-
Konferensbidrag (refereegranskat)abstract
- In the age of the General Data Protection Regula-tion (GDPR) and the California Consumer Privacy Act (CCPA),privacy and consent control have become even more apparent forevery-day web users. Privacy banners in all shapes and sizes askfor permission through more or less challenging designs and makeprivacy control more of a struggle than they help users’ privacy.In this paper, we present a novel solution expanding the AdvancedData Protection Control (ADPC) mechanism to bridge currentgaps in user data and privacy control. Our solution moves theconsent control to the browser interface to give users a seamlessand hassle-free experience, while at the same time offering contentproviders a way to be legally compliant with legislation. Throughan extensive review, we evaluate previous works and identifycurrent gaps in user data control. We then present a blueprintfor future implementation and suggest features to support privacycontrol online for users globally. Given browser support, thesolution provides a tangible path to effectively achieve legallycompliant privacy and consent control in a user-oriented mannerthat could allow them to again browse the web seamlessly.
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| 30. |
- Bruhner, Carl Magnus, 1988-, et al.
(författare)
-
Changing of the Guards: Certificate and Public Key Management on the Internet
- 2022
-
Ingår i: Passive and active measurement (PAM 2022). - Cham : Springer International Publishing. - 9783030987855 - 9783030987848 ; , s. 50-80
-
Konferensbidrag (refereegranskat)abstract
- Certificates are the foundation of secure communication over the internet. However, not all certificates are created and managed in a consistent manner and the certificate authorities (CAs) issuing certificates achieve different levels of trust. Furthermore, user trust in public keys, certificates, and CAs can quickly change. Combined with the expectation of 24/7 encrypted access to websites, this quickly evolving landscape has made careful certificate management both an important and challenging problem. In this paper, we first present a novel server-side characterization of the certificate replacement (CR) relationships in the wild, including the reuse of public keys. Our data-driven CR analysis captures management biases, highlights a lack of industry standards for replacement policies, and features successful example cases and trends. Based on the characterization results we then propose an efficient solution to an important revocation problem that currently leaves web users vulnerable long after a certificate has been revoked.
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| 31. |
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| 32. |
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| 33. |
- Carlsson, Axel C., et al.
(författare)
-
Country of birth-specific and gender differences in prevalence of diabetes in Sweden
- 2013
-
Ingår i: Diabetes Research and Clinical Practice. - : Elsevier BV. - 0168-8227 .- 1872-8227. ; 100:3, s. 404-408
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim was to investigate country or region of birth-specific prevalence and gender differences of diabetes in residents in Sweden, using Swedish-born men and women as referent. Methods: The Apolipoprotein MOrtality RISk (AMORIS) cohort was used (184,000 men and 151,453 women) aged between 20 and 80 years, with data from the CALAB laboratory, Stockholm, 1985-1996. Diabetes was defined as fasting glucose >= 7.0 mmol/L or a hospital diagnosis of diabetes. Country of birth was obtained by linkage to Swedish Censuses 1970-1990. Standardized prevalence rate ratios (SPRR) with 95% confidence intervals (95% CI) were estimated. Results: Five groups of women and one group of men had a significantly higher prevalence than Swedish-born (based on SPRR): women born in Iraq (6.0 (95% CI 1.3-28.9)), North Africa (6.9 (95% CI 3.1-15.3)), South Asia (3.1 (95% CI 1.0-10.0)), Syria (5.3 (95% CI 1.8-16.0)), Turkey (3.7 (95% CI 1.2-10.9)) and men born in other Middle Eastern countries (2.3 (95% CI 1.0-5.5)). Swedish-born men had a higher age-standardized prevalence of diabetes (3.9%) than Swedish born women ( 2.5%). A higher prevalence among men was also seen in other Western countries. In contrast, a higher age-standardized prevalence among women was observed in immigrants from Turkey (8.9% vs. 3.1%, p < 0.001), Syria (13.1% vs. 4.0%, p = 0.002), and North Africa (16.8% vs. 6.6%, p < 0.001). Conclusion: Female immigrants to Sweden from Iraq, North Africa, South Asia, Syria, and Turkey have an increased prevalence of diabetes of substantial public health concern.
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| 34. |
- Carlsson, Göran, et al.
(författare)
-
Compound heterozygous HAX1 mutations in a Swedish patient with severe congenital neutropenia and no neurodevelopmental abnormalities
- 2009
-
Ingår i: Pediatric Blood & Cancer. - : Wiley. - 1545-5009 .- 1545-5017. ; 53:6, s. 1143-1146
-
Tidskriftsartikel (refereegranskat)abstract
- Kostmann disease or severe congenital neutropenia (SCN) is an autosomal recessive disorder of neutrophil production. Homozygous HAX1 mutations were recently identified in SCN patients belonging to the original family in northern Sweden described by Kostmann. Moreover, recent studies have suggested an association between neurological dysfunction and HAX1 deficiency. Here we describe a patient with a compound heterozygous HAX1 mutation consisting of a nonsense mutation (c.568C > T, p.Glu190X) and a frame-shift mutation (c.91delG, p.Glu31LysfsX54) resulting in a premature stop codon. The patient has a history of neutropenia and a propensity for infections, but has shown no signs of neurodevelopmental abnormalities.
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| 35. |
- Carlsson, Göran, et al.
(författare)
-
Kostmann syndrome or infantile genetic agranulocytosis, part two : Understanding the underlying genetic defects in severe congenital neutropenia
- 2007
-
Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 96:6, s. 813-819
-
Forskningsöversikt (refereegranskat)abstract
- Congenital neutropenia in man was first reported 50 years ago by the Swedish paediatrician Rolf Kostmann. He coined the term 'infantile genetic agranulocytosis' for this condition, which is now known as Kostmann syndrome. Recent studies have revealed mutations in ELA-2, encoding the neutrophil granule protease, neutrophil elastase, in autosomal dominant neutropenia, and mutations in HAX-1, encoding an anti-apoptotic protein, in autosomal recessive neutropenia. Conclusion: Future studies should aim to clarify the mechanisms underlying the evolution of secondary malignancies in these patients.
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| 36. |
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| 37. |
- Carlsson, Jörgen, et al.
(författare)
-
En historia om koncernredovisning: Den Stockholm-Göteborgska drabbningen
- 2023
-
Ingår i: Balans Fördjupning.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Debatten om redovisningsfrågor har numera flyttat från den nationella till den internationella arenan och får inte längre så mycket utrymme i Sverige. Annorlunda var det på 1970-, 1980- och 1990-talen då inte minst tidskriften Balans utgjorde en viktig arena för samtalet om redovisningens utveckling, skriver Jörgen Carlsson och Niklas Sandell vid Ekonomihögskolan i Lund. I sin artikel lyfter de fram ett färgstarkt exempel på hur det kunde låta när svenska redovisningsspecialister debatterade koncernredovisning i början av 1990-talet.
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| 38. |
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| 39. |
- Carlsson, Jörgen, et al.
(författare)
-
Kommunala koncerner : En studie av bolagsstrukturer, budgetar och ägardirektiv
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Utvecklingen mot mer komplicerade kommunala koncerner förändrar förutsättningarna för och ställer andra krav på kommunal koncernstyrning. Syftet med denna studie är att kartlägga dels hur de kommunala koncernerna i Skånes kommuner är strukturerade, dels hur den formella styrningen av dessa koncerner är utformad. Fokus är på andra organisationsformer i den kommunala koncernen än nämnds- och förvaltningsorganisationen, särskilt bolag och kommunalförbund. Rapporten har delats in i två delar: Koncernstrukturer och Styrdokument.
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| 40. |
- Carlsson, Jörgen, et al.
(författare)
-
Koncernredovisning
- 2010
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Denna bok beskriver och förklarar koncernredovisningens logik och teknik. Syftet är att både skapa principiell förståelse för koncernen som redovisningsenhet och god kunskap i koncernredovisningens teknik. Bokens innehåll kan sammanfattas i följande punkter: •Koncernredovisningsteknik •Koncernredovisningslogik •Lagar och regler •Analys av koncernredovisning Koncernredovisning innehåller rikligt med strukturerade och lättillgängliga exempel och övningar. Med boken följer ett lösningshäfte som innehåller utförliga lösningar till samtliga övningsuppgifter. Stora delar av boken har skapats i utbildningssammanhang och grundar sig på erfarenheter från lärosalen. De pedagogiska insikterna kompletteras av författarnas praktiska erfarenheter av koncernredovisning i såväl stora som små företag. Boken är lämplig för utbildning vid universitet och högskolor samt annan kvalificerad utbildning. Den vänder sig även till praktiker som vill lära sig eller repetera grundläggande koncernredovisning.
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| 41. |
- Carlsson, Jörgen, et al.
(författare)
-
Koncernredovisning
- 2014
-
Bok (övrigt vetenskapligt/konstnärligt)
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| 42. |
- Carlsson, Jörgen, et al.
(författare)
-
Koncernredovisning
- 2018. - 3
-
Bok (populärvet., debatt m.m.)abstract
- Denna bok beskriver och förklarar koncernredovisningens logik och teknik. Syftet är att både skapa principiell förståelse för koncernen som redovisningsenhet och god kunskap i koncernredovisningens teknik.
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| 43. |
- Carlsson, Jörgen, et al.
(författare)
-
Koncernredovisning
- 2024. - 4
-
Bok (populärvet., debatt m.m.)
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| 44. |
- Carlsson, Jörgen, et al.
(författare)
-
Mandolin AB : Ett praktikfall i redovisning och ekonomisk analys
- 2023. - 1
-
Bok (populärvet., debatt m.m.)abstract
- Mandolin AB är ett praktikfall i bokföring, bokslut och ekonomisk analys. I praktikfallet ingår att sköta den löpande bokföringen, ta fram bokslut och årsredovisning samt att göra ekonomiska analyser av företaget Mandolin AB. Praktikfallet syftar till att ge ett helhetsperspektiv på arbetet med ekonomisk rapportering i ett mindre företag, inklusive praktisk kunskap om och förståelse för bokförings- och bokslutslogik. Praktikfallet innehåller, utöver ett autentiskt bokföringsmaterial, textavsnitt om de sakområden som behandlas samt uppgifts- och arbetsbeskrivningar. Vägledning lämnas till särskilt intressanta eller svåra bokföringsposter och bedömningar.
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| 45. |
- Carlsson, Jörgen, et al.
(författare)
-
Nedskrivningsprövning av goodwill: före eller efter skatt?
- 2013
-
Ingår i: Balans: tidskrift för redovisning och revision. - 0346-8208. ; 39:4, s. 27-30
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- I artikeln utreds sambandet mellan diskonteringsräntan före och efter skatt och hur detta samband påverkar beräkningar vid nedskrivningsprövning.
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| 46. |
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| 47. |
- Carlsson, Jörgen, et al.
(författare)
-
Sammanställd redovisning : - mot en förbättrad kommunal koncernredovisningspraktik
- 2014
-
Ingår i: Balans. - Stockholm : FAR. - 0346-8208. ; :4, s. 6-8
-
Recension (populärvet., debatt m.m.)abstract
- I syfte att utveckla kvaliteten på kommuners sammanställda redovisning har Rådet för Kommunal Redovisning (RKR) tagit fram en skrift som är tänkt att utgöra ett stöd för dem som arbetar med att ta fram sammanställd redovisning. I denna artikel diskuterar författarna till skriften, Jörgen Carlsson och Niklas Sandell, tillsammans med Torbjörn Tagesson, kanslichef vid RKR, den kommunala redovisningens utmaningar och några av RKR:s ställningstaganden avseende de riktlinjer som gäller vid framtagande av en kommunal koncernredovisning.
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| 48. |
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| 49. |
- Carlsson, Jörgen, et al.
(författare)
-
Sammanställd redovisning : En kartläggning av Sveriges kommuners årsredovisningar
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Betydande delar av den kommunala verksamheten bedrivs utanför nämnds- och förvaltningsorganisationen, i bolag, kommunalförbund etc. En stor del avSveriges kommuners tillgångar, åtaganden och kostnader redovisas därför inte iförvaltningsorganisationen. Av den anledningen är den sammanställda redovisningen, den ”kommunala koncernredovisningen” betydelsefull, för att visa hela kommunens ekonomi, och därmed ekonomiska hushållning. Trots att det, ur såväl ett meborgarperspektiv som ett styrningsperspektiv, borde vara intressant att visa kommunens samlade tillgångar, skulder och kostnader visar denna studie av Sveriges kommuners årsredovisningar för 2014 att den sammanställda redovisningen tillmäts relativt liten betydelse. Detta visar sig bl.a. genom att den sammanställda redovisningen i förvaltningsberättelsen, och i analysen av kommunernas ekonomi, ges ett begränsat utrymme och en undanskymd plats. Även i årsredovisningarnas mer tekniska delar, där resultat och balansräkningar presenteras, redovisningsprinciper beskrivs och tilläggsupplysningar lämnas, finns betydande brister. Studiens sammanfattande slutsats är att förbättrad kvalitet och analys av den sammanställda redovisningen är nödvändig om denna ska kunna användas för ledning och styrning av den kommunala verksamheten
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| 50. |
- Carlsson, Jörgen, et al.
(författare)
-
Sammanställd redovisning i förgrunden eller bakgrunden : En kartläggning av Skånes kommuners årsredovisningar
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Betydande delar av denkommunalaverksamhetenbedrivs utanför nämnds-och förvaltningsorganisationen, i bolag, kommunalförbund etc. En stor del av kommunernas tillgångar, åtaganden och kostnader redovisas därför inte i förvaltningsorganisationen. Därför är den sammanställda redovisningen, ”kommunal koncernredovisning” betydelsefull,för att visa hela kommunens ekonomi, och därmed ekonomiska hushållning.Trots att det, ur såväl ett meborgarperspektiv som ett styrningsperspektiv,borde vara intressant att visa kommunens samlade tillgångar, skulderoch kostnader visar denna studie av de skånska kommunernas årsredovisningar för 2014 att den sammanställda redovisningen tillmäts relativt liten betydelse. Detta visar sigbl.a.genomattkommuner vid övergripande presentation avverksamheternaendast lämnar ett fåtal, oftast intenågon, uppgift från den sammanställdaredovisningen. Även i förvaltningsberättelsen gesden sammanställda redovisningenbegränsat utrymme ochen undanskymd plats.För årsredovisningens mer tekniska delar där resultat-och balansräkningar presenteras, redovisningsprinciper beskrivs och tilläggsupplysningar lämnas finner viatt det finns en stor förbättringspotential. Förbättrad kvalitet och analys av den sammanställda redovisningen torde också varanödvändig om dennaska kunna användas för ledning och styrning av hela den kommunala verksamheten.
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