| 11. |
- Diamond, Miriam, et al.
(author)
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Exploring the planetary boundary for chemical pollution
- 2015
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In: Environment International. - : Elsevier BV. - 0160-4120 .- 1873-6750. ; 78, s. 8-15
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Research review (peer-reviewed)abstract
- Rockström et al. (2009a, 2009b) have warned that humanity must reduce anthropogenic impacts defined by nine planetary boundaries if “unacceptable global change” is to be avoided. Chemical pollution was identified as one of those boundaries for which continued impacts could erode the resilience of ecosystems and humanity. The central concept of the planetary boundary (or boundaries) for chemical pollution (PBCP or PBCPs) is that the Earth has a finite assimilative capacity for chemical pollution, which includes persistent, as well as readily degradable chemicals released at local to regional scales, which in aggregate threaten ecosystem and human viability. The PBCP allows humanity to explicitly address the increasingly global aspects of chemical pollution throughout a chemical's life cycle and the need for a global response of internationally coordinated control measures. We submit that sufficient evidence shows stresses on ecosystem and human health at local to global scales, suggesting that conditions are transgressing the safe operating space delimited by a PBCP. As such, current local to global pollution control measures are insufficient. However, while the PBCP is an important conceptual step forward, at this point single or multiple PBCPs are challenging to operationalize due to the extremely large number of commercial chemicals or mixtures of chemicals that cause myriad adverse effects to innumerable species and ecosystems, and the complex linkages between emissions, environmental concentrations, exposures and adverse effects. As well, the normative nature of a PBCP presents challenges of negotiating pollution limits amongst societal groups with differing viewpoints. Thus, a combination of approaches is recommended as follows: develop indicators of chemical pollution, for both control and response variables, that will aid in quantifying a PBCP(s) and gauging progress towards reducing chemical pollution; develop new technologies and technical and social approaches to mitigate global chemical pollution that emphasize a preventative approach; coordinate pollution control and sustainability efforts; and facilitate implementation of multiple (and potentially decentralized) control efforts involving scientists, civil society, government, non-governmental organizations and international bodies.
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| 12. |
- Du, Manxing, et al.
(author)
-
Analysis of prefetching schemes for TV-on-Demand service
- 2015
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In: ICDT 2015 : the Tenth International Conference on Digital Telecommunications. - : International Academy, Research and Industry Association (IARIA). - 9781612083964
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Conference paper (peer-reviewed)abstract
- TV-on-Demand service has become one of the most popular Internet applications that continuously attracts higher user interests. With rapidly increasing user demand, the existing network conditions may not be able to ensure low start-up delay of video playback. Prefetching has been broadly investigated to cope with the start-up latency problem which is also known as user perceived latency. In this paper, we analyse request patterns for TV programs from a popular Swedish TV service provider over 11 weeks. According to the analysis, we propose a prefetching scheme at the user end to preload videos before user requests. Our prefetching scheme significantly improves the cache hit ratio compared to terminal caching and we note that there is a potential to further improve prefetching performance by customizing prefetching schemes for different video categories. We further present a cost model to determine the optimal number of videos to prefetch. Finally, we discuss available time for prefetching and suggest that when to make prefetching decisions depends on the user demand patterns of different video categories.
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| 13. |
- Habtegebreil, Haile, et al.
(author)
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Impact of TCP BBR on CUBIC traffic : a mixed workload evaluation
- 2018
-
Conference paper (peer-reviewed)abstract
- A recently proposed congestion control algorithm (CCA) called BBR (Bottleneck Bandwidth and Round-trip propagation time) has shown a lot of promise in avoiding some of the problems that have plagued loss-based CCAs. Nevertheless, deployment of a new alternative algorithm requires a thorough evaluation of the effect of the proposed alternative on established transport protocols like TCP CUBIC. Furthermore, evaluations that consider the heterogeneity of Internet traffic sizes would provide a useful insight into the deployability of an algorithm that introduces sweeping changes across multiple algorithm components. Yet, most evaluations of BBR’s impact and competitive fairness have focused on the steady-state performance of large flows. This work expands on previous studies of BBR by evaluating BBR’s impact when the traffic consists of flows of different sizes. Our experiments show that under certain circumstances BBR’s startup phase can result in a significant reduction of the throughput of competing large CUBIC flows and the utilization of the bottleneck link. In addition, the steady-state operation of BBR can have negative impact on the performance of bursty flows using loss-based CCAs over bottlenecks with buffer sizes as high as two times the bandwidth-delay product.
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| 14. |
- Kreuger, Per, et al.
(author)
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Zero configuration adaptive paging (zCap)
- 2012
-
In: VTC Fall 2012. - : IEEE Communications Society. - 9781467318792
-
Conference paper (peer-reviewed)abstract
- Today, cellular networks rely on fixed collections of cells (tracking areas) for handset localisation. This management parameter is manually configured and maintained and is not regularly adapted to changes in use patterns. We present a decentralised approach to localisation, based on a self-adaptive probabilistic mobility model. Estimates of model parameters are built from observations of mobility patterns collected online using a distributed algorithm. Based on these estimates, dynamic local neighbourhoods of cells are formed and maintained by the mobility management entities of the network. These neighbourhoods replace the static tracking areas used in current implementations by using the tracking area list facility of LTE. The model is also used to derive a multi phase paging scheme, where the division of cells into consecutive phases is optimal with respect to a set balance between response times and paging cost. The approach requires no manual tracking area configuration, and performs localisation efficiently in terms of number of location updates, page
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| 15. |
- Li, Jie, et al.
(author)
-
A five year perspective of traffic pattern evolution in a residential broadband access network
- 2012
-
In: Future Network & MobileSummit 2012. - 9781905824304
-
Conference paper (peer-reviewed)abstract
- In this paper we describe a systematic study on long-term evolution of residential broadband Internet traffic covering 5 calendar years from June 2007 to May 2011. The traffic evolution is characterized both in the term of the total traffic volume, as well as the traffic volumes and shares for different application categories (file sharing, video streaming etc.), with the focus on comparing the traffic on the per IP user basis and among different broadband subscription groups. The results show that the average daily total traffic generated by each private end user increased only by about 33 % during the past 5 years. Further, the results show that the P2P filesharing has been dominating the network total traffic, but the daily file-sharing traffic volume per end user largely remains the same. Also, the daily streaming-media traffic volume per end user has increased dramatically by over 500% during the studied period of time. In the meantime, the daily web-browsing traffic volume per end user has increased by about 300%. Finally, a further investigation among 4 different FTTH broadband subscription groups with 1, 10 , 30, and 100 Mbit/s symmetric access speeds shows that the lower the access speed, the more diversified the end user traffic tend to be.
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| 16. |
- Li, Jie, et al.
(author)
-
Performance analysis of local caching replacement policies for internet video streaming services
- 2014
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In: SoftCOM 2014. - : IEEE Communications Society. - 9789532900521
-
Conference paper (peer-reviewed)abstract
- In this work, the performance of 5 representative caching replacement policies was investigated and compared for caching Internet video-on-demand (VoD) in local access networks. Two measured traces of end-user requests were used in the analyses for two typical VoD services: TV-on-demand and user generated content represented by YouTube. The studied policies range from simple least recently used (LRU) and least frequently used (LFU) algorithms to more advanced ones denoted as LFU-dynamic lifespan (LFU-DL), Adaptive replacement cache (ARC) and Greedy-dual size frequency (GDSF). Our results show that the ARC policy always outperforms the other policies due to its adaptive nature and its ability to track changes in the traffic patterns. On the other hand, the simple LRU policy can also achieve a caching performance which is comparable to that of the more advanced ARC policy especially for the TV-on-demand service when the potential caching gain is high. On the contrary, the simple LFU policy always shows the poorest performance.However, by applying a proper lifespan supplement under the LFU-DL policy, the caching performance can be effectively enhanced to the level achievable using ARC and LRU policies. Moreover, the GDSF policy does not outperform simple LRU or LFU-DL, especially for YouTube video clips when the potential caching gain is relatively low. The advantage of GDSF manifested in our analysis is, however, its outstanding cache space usage efficiency among the five studied caching algorithms.
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| 17. |
- Li, Jie, et al.
(author)
-
YouTube traffic content analysis in the perspective of clip category and duration
- 2013
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In: 2013 Fourth International Conference on the Network of the Future (NOF 2013). - : IEEE Communications Society. - 9781479916429
-
Conference paper (peer-reviewed)abstract
- In this work, we study YouTube traffic characteristics in a medium-sized Swedish residential municipal network that has ~ 2600 mainly FTTH broadband-connected households. YouTube traffic analyses were carried out in the perspective of video clip category and duration, in order to understand their impact on the potential local network caching gains. To the best of our knowledge, this is the first time systematic analysis of YouTube traffic content in the perspective of video clip category and duration in a residential broadband network. Our results show that the requested YouTube videoclips from the end users in the studied network were imbalanced in regarding the video categories and durations. The dominating video category was Music, both in terms of the total traffic share as well as the contribution to the overall potential local network caching gain. In addition, most of the requested video clips were between 2-5 min in duration, despite video clips with durations over 15 min were also popular among certain video categories, e.g. film videos.
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| 18. |
- Nordell, Viktor, et al.
(author)
-
Concurrency and locality of content demand
- 2013
-
In: 2013 International Conference on Smart Communications in Network Technologies (SaCoNeT 2013). - 9781479906956
-
Conference paper (peer-reviewed)abstract
- Distribution of media data over the Internet is increasing in popularity and volume. This poses challenges not only for network operators but also for service providers when it comes to serving the demand in a cost-efficient way. In this paper, we approach this problem by investigating the potential of co-operative approaches where locality in space (users in the same network) and locality in time (concurrent downloads) are exploited such that as many requests as possible may behandled inside the access and metro networks. This approach may contribute not only to reducing transport costs (less traffic in core networks and at peering points) by but also improve the end user experience (by reduced round trip times and exclusion of some possible bottlenecks). To this end we develop a method to measure the possible gains from, firstly, optimal handling of concurrent downloads and, secondly, optimal utilization localavailability. We apply the method to BitTorrent data from two metropolitan access networks and find that the bandwidth savings amount to between 10% and 20% when optimizing concurrent downloads and between 56% and 66% when exploiting local availability with a simulated network cache.
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| 19. |
- Scheringer, Martin, et al.
(author)
-
Planetary boundaries for chemical pollution
- 2012
-
In: Dioxin 2012 - 32nd International Symposium on Halogenated Persistent Organic Compounds.
-
Conference paper (peer-reviewed)abstract
- Based on the concept by Rockström et al the paper discusses the principles of the concept in relation to chemical pollution and the specific challenges associated to that. The paper conclude the chemical pollution is certainly a strong anthropogenic impact of global relevance. However, because of the local or regional nature of many exposures and effects caused by chemicals, there is probably not a single tipping point for the global system that would have to be reflected by a planetary boundary. Therefore, in order to assess and manage chemical pollution, it seems to be more promising to focus on certain classes of chemicals separately and to derive boundaries of different types for these classes of chemicals, as illustrated in the paper for CFCs, POPs and food contaminants.
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| 20. |
- Størsrud, Stine, 1972, et al.
(author)
-
Adult coeliac patients do tolerate large amounts of oats.
- 2003
-
In: European journal of clinical nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 57:1, s. 163-9
-
Journal article (peer-reviewed)abstract
- The aim of the present study was to investigate whether adult patients with coeliac disease in remission could include large amounts of oats in their daily gluten-free diet for an extended period of time without adverse effects. DESIGN, SUBJECTS AND METHODS: Twenty adult coeliac patients in remission included large amounts of uncontaminated rolled oats in their daily diet for a prolonged period. The examinations, performed four times during the study period, included small bowel endoscopy with biopsies, blood samples (nutritional status, serological analysis), height and body weight, gastrointestinal symptoms and dietary records. Gastrointestinal symptoms and diet were also investigated through unannounced telephone interviews once a month during the study period.
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