| 1. |
- Klionsky, Daniel J., et al.
(författare)
-
Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
-
Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
-
Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
|
|
| 2. |
- Wang, Zhaoming, et al.
(författare)
-
Imputation and subset-based association analysis across different cancer types identifies multiple independent risk loci in the TERT-CLPTM1L region on chromosome 5p15.33
- 2014
-
Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 23:24, s. 6616-6633
-
Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have mapped risk alleles for at least 10 distinct cancers to a small region of 63 000 bp on chromosome 5p15.33. This region harbors the TERT and CLPTM1L genes; the former encodes the catalytic subunit of telomerase reverse transcriptase and the latter may play a role in apoptosis. To investigate further the genetic architecture of common susceptibility alleles in this region, we conducted an agnostic subset-based meta-analysis (association analysis based on subsets) across six distinct cancers in 34 248 cases and 45 036 controls. Based on sequential conditional analysis, we identified as many as six independent risk loci marked by common single-nucleotide polymorphisms: five in the TERT gene (Region 1: rs7726159, P = 2.10 × 10(-39); Region 3: rs2853677, P = 3.30 × 10(-36) and PConditional = 2.36 × 10(-8); Region 4: rs2736098, P = 3.87 × 10(-12) and PConditional = 5.19 × 10(-6), Region 5: rs13172201, P = 0.041 and PConditional = 2.04 × 10(-6); and Region 6: rs10069690, P = 7.49 × 10(-15) and PConditional = 5.35 × 10(-7)) and one in the neighboring CLPTM1L gene (Region 2: rs451360; P = 1.90 × 10(-18) and PConditional = 7.06 × 10(-16)). Between three and five cancers mapped to each independent locus with both risk-enhancing and protective effects. Allele-specific effects on DNA methylation were seen for a subset of risk loci, indicating that methylation and subsequent effects on gene expression may contribute to the biology of risk variants on 5p15.33. Our results provide strong support for extensive pleiotropy across this region of 5p15.33, to an extent not previously observed in other cancer susceptibility loci.
|
|
| 3. |
- Erman, David, et al.
(författare)
-
Evaluation of Swarm Video Streaming
- 2010
-
Konferensbidrag (refereegranskat)abstract
- IPTV has been hailed as a “killer app'' of the Internet for a long time, but it has yet to really make a major breakthrough, due to various technical and political reasons. The recent influx of community-driven video distribution has re-actualized the research into efficient distribution methods for streaming video. In this paper, we suggest a number of modifications and extensions to the BitTorrent distribution and replication system to make it suitable for use in providing a streaming video delivery service, and implement parts of these in a simulator. Also, we report on a simulation study as well as a large-scale real-world study of the extensions on PlanetLab. Results show that BitTorrent can be used as a bandwidth-efficient alternative to traditional IPTV solutions.
|
|
| 4. |
- Ngoga, Said Rutabayiro, et al.
(författare)
-
A Simple Time-based Threshold Strategy for Dynamic Spectrum Access
- 2012
-
Konferensbidrag (refereegranskat)abstract
- In dynamic spectrum access networks, the unused licensed spectrum of primary users (PU) is opened to unlicensed secondary user (SU) for improving spectrum efficiency. The problem we study in this paper is to maximize the SU throughput while guaranteeing PU performance. We design a simple time-based threshold strategy to maximize the SU throughput while guaranteeing the PU performance by learning directly from the interaction with PU environment. At a given time, the SU decides if it should transmit and if so to protect the PU performance. It is observed that such strategies perform closely to the strategy optimized based on prior knowledge about PU traffic models. Simulations are used for performance evaluation.
|
|
| 5. |
- Ngoga, Said Rutabayiro, et al.
(författare)
-
Beacon-Enabled Cognitive Access for Dynamic Spectrum Access
- 2012
-
Konferensbidrag (refereegranskat)abstract
- In dynamic spectrum access networks, the unused licensed spectrum used by primary users (PU) is opened to unlicensed secondary users (SU) for improving spectrum efficiency. We design a simple time-based threshold policy for collective protection of PUs, enabled by an out-of-band channel. In particular, multiple SUs may be widely distributed in a geographic location. The interference that collocated SUs cause to each other, termed self-interference, becomes a major source that may degrade the SUs communication performance. We establish an analytical framework for carrier sense multiple access (CSMA) based coexistence mechanisms when integrated into a family of time based threshold policies, and study its performance though theoretical analysis.
|
|
| 6. |
- Popescu, Alexandru, et al.
(författare)
-
Communication Mechanisms for Cognitive Radio Networks
- 2013
-
Konferensbidrag (refereegranskat)abstract
- Comprehensive communication in cognitive radio networks is an important research topic within the scope of empowering cognitive radio functionality in beyond-4G mobile networks. Providing communication for secondary users without interference with primary users is an ambitious task, which requires innovative management architecture designs and routing solutions. Operational challenges such as opportunistic spectrum access, solving problems related to spectrum and network heterogeneities and requests for the provisioning of Quality-of-Service to different applications must be resolved. As part of a novel management architecture, the paper advances a new approach to end-to-end communication in cognitive radio networks based on combining ad-hoc algorithms with spectrum mobility algorithms.
|
|
| 7. |
|
|
| 8. |
- Popescu, Alexandru, et al.
(författare)
-
On Mobility Generated Signaling in Cognitive Radio Network Clusters
- 2013
-
Konferensbidrag (refereegranskat)abstract
- The rapid migration towards wireless connectivity means that the radio spectrum must be efficiently utilized to conserve capacity and to avoid overcrowding, particularly in densely populated areas. Towards this goal, cognitive radio technology is a key concept. The basic idea is to allow unlicensed users access to licensed spectrum, under the condition that the interference perceived by the licensed users is minimal. A novel architecture designed and developed at the application layer has been suggested by researchers at Blekinge Institute of Technology for the management of cognitive radio networks. Emphasizing on signaling facilities in this architecture and common control channel dimensioning aspects, the paper reports on simulation results regarding node mobility for a particular network model. To reduce the energy consumption of mobile devices, innovative signaling strategies are a very important topic to consider in novel mobile system architectures.
|
|
| 9. |
- Rutabayiro Ngoga, Said, et al.
(författare)
-
On Multi-channel Opportunistic Access in Heterogeneous Cognitive Radio Networks
- 2013
-
Konferensbidrag (refereegranskat)abstract
- In the paper, we study optimal transmission strategies in multi-channel opportunistic spectrum access (OSA) networks where one secondary user (SU) opportunistically accesses multiple orthogonal channels of primary users (PUs) under a continuous time Markov chain modeling of the channel occupancy by the PUs. Referred to as tunable threshold strategy, at a given time the SU chooses one channel of a given PU, decides if it should transmits or not and if so it protects the PU of this channel. To be operational, such a structure depends on the capability of the SU radio front-end to perform channel sensing. We consider one scenario where the SU node can simultaneously sense multiple channels and another scenario where the SU node can sense only one channel at a time. For each scenario, we develop the structure of the optimal transmission strategy and analyse the performance. We show that the optimal transmission strategy can be implemented using a simple tunable threshold algorithm.
|
|
| 10. |
|
|
| 11. |
- Yao, Yong
(författare)
-
A Software Framework for Prioritized Spectrum Access in Heterogeneous Cognitive Radio Networks
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today, the radio spectrum is rarely fully utilized. This problem is valid in more domains, e.g., time, frequency and geographical location. To provide an efficient utilization of the radio spectrum, the Cognitive Radio Networks (CRNs) have been advanced. The key idea is to open up the licensed spectrum to unlicensed users, thus allowing them to use the so-called spectrum opportunities as long as they do not harmfully interfere with licensed users. An important focus is laid on the limitation of previously reported research efforts, which is due to the limited consideration of the problem of competition among unlicensed users for spectrum access in heterogeneous CRNs. A software framework is introduced, which is called PRioritized Opportunistic spectrum Access System (PROAS). In PROAS, the heterogeneity aspects of CRNs are specifically expressed in terms of cross-layer design and various wireless technologies. By considering factors like ease of implementation and efficiency of control, PROAS provides priority scheduling based solutions to alleviate the competition problem of unlicensed users in heterogenous CRNs. The advanced solutions include theoretical models, numerical analysis and experimental simulations for performance evaluation. By using PROAS, three particular CRN models are studied, which are based on ad-hoc, mesh-network and cellular-network technologies. The reported results show that PROAS has the ability to bridge the gap between research results and the practical implementation of CRNs.
|
|
| 12. |
- Yao, Yong
(författare)
-
A Spectrum Decision Support System for Cognitive Radio Networks
- 2012
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Cognitive Radio Networks (CRNs) offer a promising capability of alleviating the problem of spectrum insufficiency. In CRNs, the licensed spectrum channels are either exclusively reserved for licensed users or temporarily used by unlicensed users. The requirement for unlicensed users is to not harmfully impair the licensed users transmissions. Because of this, the unlicensed users must solve the task to decide which available channels should be selected. The selection process is often referred to as spectrum decision, with the aim to optimize the transmission performance of unlicensed users. A support system for CRNs is introduced, which is called Spectrum Decision Support System (SDSS). SDSS provides an intelligent spectrum decision strategy that integrates different decision making algorithms and takes into account various channel characterization parameters. The objective is to develop a scientific framework for decision making in CRNs, which involve theoretical analysis, simulation evaluation and practical implementation. Three important components of SDSS are discussed: 1) setting up an overlay decision maker, 2) prediction based spectrum decision strategy and 3) queuing modeling of CRNs. The reported results indicate the feasibility of the suggested algorithms.
|
|
| 13. |
- Yao, Yong, et al.
(författare)
-
A System for Spectrum Decision in Cognitive Radio Networks
- 2012
-
Konferensbidrag (refereegranskat)abstract
- In Cognitive Radio (CR) networks, licensed radio channels are allowed to be used by Secondary Users (SUs) as long as SUs do not harmfully impair the transmission of Primary Users (PUs). Therefore, a crucial task for SUs is to decide which available channel should be selected, the so-called spectrum decision. To provide intelligent spectrum decision strategy to SUs, we suggest a system called Spectrum Decision Support System (SDSS). SDSS takes into account both heterogeneity aspects and interoperability requirements of CR networks. By this, SDSS is capable of jointly considering various channel characterizations and different decision making algorithms for doing spectrum decision. The paper is reporting the SDSS architecture as well as the related work-in-progress.
|
|
| 14. |
- Yao, Yong, et al.
(författare)
-
Cognitive Radio Spectrum Decision Based on Channel Usage Prediction
- 2012
-
Konferensbidrag (refereegranskat)abstract
- The paper is about a new strategy suggested for spectrum decision in Cognitive Radio (CR) networks. By jointly considering sensing error, Secondary Users (SUs) competition and SUs transmission collision, a new parameter called Channel Usage State (CUS) is introduced. For a particular channel, we predict the respective probabilities of occurrence of CUS states by using the LeZi-update scheme. We also adopt a fuzzy comparison algorithm to combine the prediction results as a joint value. The largest joint value is associated with the most available channel for access by SUs in the near future. By comparing with random channel access, the suggested strategy can improve SUs transmission throughput. This is demonstrated by the simulation evaluations.
|
|
| 15. |
- Yao, Yong, et al.
(författare)
-
Competition-Based Channel Selection for Cognitive Radio Networks
- 2012
-
Konferensbidrag (refereegranskat)abstract
- In cognitive radio networks, unlicensed users need to learn from environmental changes. This is a process that can be done in a cooperative or non-cooperative manner. Due to the competition for channel utilization among unlicensed users, the non-cooperative approach may lead to overcrowding in the available channels. This paper is about a fuzzy-logic based decision making algorithm for competition-based channel selection. The underlying decision criterion integrates both the statistics of licensed users' channel occupancy and the competition level of unlicensed users. By using such an algorithm, the unlicensed user competitors can achieve an efficient sharing of the available channels. Simulation results are reported to demonstrate the performance and effectiveness of our suggested algorithm.
|
|
| 16. |
- Yao, Yong, et al.
(författare)
-
On Fuzzy Logic-Based Channel Selection in Cognitive Radio Networks
- 2014
-
Ingår i: Software-Defined and Cognitive Radio Technologies for Dynamic Spectrum Management. - Hershey, PA 17033, USA : IGI-Global. - 9781466665712
-
Bokkapitel (refereegranskat)abstract
- Cognitive radio networks are a new technology based on which unlicensed users are allowed access to licensed spectrum under the condition that the interference perceived by licensed users is minimal. That means unlicensed users need to learn from environmental changes and to take appropriate decisions regarding the access to the radio channel. This is a process that can be done by unlicensed users in a cooperative or non-cooperative way. Whereas the non-cooperative algorithms are risky with regard to performance, the cooperative algorithms have the capability to provide better performance. Our paper reports therefore a new fuzzy logic based decision making algorithm for channel selection. The underlying decision criterion considers statistics of licensed users channel occupancy as well as information about the competition level of unlicensed users. Our theoretical studies indicate that the unlicensed users can obtain an efficient sharing of the available channels. Simulation results are reported to demonstrate the performance and effectiveness of the suggested algorithm.
|
|
| 17. |
- Yao, Yong, et al.
(författare)
-
On Prioritized Spectrum Access in Cognitive Radio Networks with Imperfect Sensing
- 2013
-
Konferensbidrag (refereegranskat)abstract
- Cognitive Radio networks allow the unlicensed users to share the available spectrum opportunities. However, this demands for solving the problem of contention among multiple unlicensed user packets for transmission. In our paper, we consider the Opportunistic Spectrum Access model for packet transmission between two unlicensed users. We suggest a priority scheme for a unlicensed user to concurrently transmit different types of packets. Our scheme reserves a fixed number of queueing places in the buffer for the prioritized packets. We study the transmission performance under both the priority scheme and imperfect spectrum sensing, with respect to the blocking probabilities, average transmission delay and transmission throughput of unlicensed users packets. The Markov chain based numerical analysis is validated by simulation experiments. Our results show that the suggested priority scheme is able to enhance transmission throughput of unlicensed users packets, together with significant decreased average transmission delay and minor decreased total transmission throughput.
|
|
| 18. |
- Yao, Yong, et al.
(författare)
-
Performance of Cognitive Radio Spectrum Access with Intra- and Inter-Handoff
- 2012
-
Konferensbidrag (refereegranskat)abstract
- Opportunistic spectrum access (OSA) is a technology that allows unlicensed users to access spectrum holes and to provide so efficient use of radio resources. Most of the studies done on OSA focus on the situation when the unlicensed user performs the spectrum handoff only within a single cognitive radio network (so-called intra-handoff). In this paper, we consider the users (licensed or unlicensed) to be able to do inter-handoff among different cognitive radio cells as well. The cells provide priority to inter-handoff users. By considering multiple cells being in steady-state, the arrival rates of inter-handoff users are determined. We study the OSA performance of unlicensed users under both intra- and inter-handoff schemes, with respect to the blocking and forced-termination probabilities of unlicensed users as well as the unlicensed user service-completion and inter-handoff throughputs. Our Markov chain based numerical analysis is validated by simulation experiments.
|
|
| 19. |
- Yao, Yong, et al.
(författare)
-
PlanetLab Automatic Control System
- 2010
-
Konferensbidrag (refereegranskat)abstract
- PlanetLab provides a global scale environment for network research. It consists of numerous controllable computer nodes. However, due to that these nodes are deployed in various network domains, there exist experimental issues, regarding network latency, resource utilization, and unpredictable behaviors of nodes. Experimenters need to pay much attention to manually adjusting their selected nodes during the whole experimental process. PLACS is a novel tool system based on PlanetLab, and composed of node selection node management. It can intelligently and automatically coordinate the involved elements, including PlanetLab nodes, experimental programs and experimenter requirements. In this article, the corresponding mechanism functionalities and implementation designs for development are presented.
|
|
| 20. |
- Yao, Yong, et al.
(författare)
-
Spectrum Decision for Cognitive Radio Networks
- 2011
-
Konferensbidrag (refereegranskat)abstract
- Cognitive Radio Networks (CRNs) are a key technology suggested to be part of 4G and beyond. The fundamental concept is to let Secondary Users (SUs) have temporal free access to spectrum bands not occupied by Primary Users (PUs). Since SUs are not allowed to cause harmful interference to PUs, SUs need to select the most available spectrum bands for access, also known as spectrum decision. In the paper, we suggest a middleware called Spectrum Decision Support System (SDSS) abstractly illustrated. The goal of SDSS is to combine the different decision methods together and to make intelligent band selection based upon partial characterizations of CRNs
|
|
| 21. |
- Zhang, Peili, et al.
(författare)
-
A Molecular Copper Catalyst for Electrochemical Water Reduction with a Large Hydrogen-Generation Rate Constant in Aqueous Solution
- 2014
-
Ingår i: Angewandte Chemie International Edition. - : Wiley. - 1433-7851 .- 1521-3773. ; 53:50, s. 13803-13807
-
Tidskriftsartikel (refereegranskat)abstract
- The copper complex [(bztpen)Cu](BF4)(2) (bztpen=N-benzyl-N,N,N-tris(pyridin-2-ylmethyl)ethylenediamine) displays high catalytic activity for electrochemical proton reduction in acidic aqueous solutions, with a calculated hydrogen-generation rate constant (k(obs)) of over 10000s(-1). A turnover frequency (TOF) of 7000h(-1)cm(-2) and a Faradaic efficiency of 96% were obtained from a controlled potential electrolysis (CPE) experiment with [(bztpen)Cu](2+) in pH2.5 buffer solution at -0.90V versus the standard hydrogen electrode (SHE) over two hours using a glassy carbon electrode. A mechanism involving two proton-coupled reduction steps was proposed for the dihydrogen generation reaction catalyzed by [(bztpen)Cu](2+).
|
|
| 22. |
- Zhou, Kaibo, et al.
(författare)
-
A Mobility Management Solution for Simultaneous Mobility with mSCTP
- 2011
-
Konferensbidrag (refereegranskat)abstract
- The paper is about mobile Stream Control Transmission Protocol (mSCTP) and the problems related to simultaneous mobility. Simultaneous mobility is when the both endpoints of a communication session are mobile and they move at about the same time. mSCTP works well in the case of non-simultaneous mobility where the SCTP association is established between a mobile endpoint and a stationary one. In the case of simultaneous mobility however, the probability of broken association may become high because both endpoints may suffer from losing address binding update. This is a consequence of the fact that the targeted addresses become unreachable. In this paper, we suggest a solution based on Host Name Address (HNA), together with pro-active Name Server, Address Handling Function (AHF) and Simultaneous Mobility Detection Function (SMDF) to eliminate this problem. Our preliminary results show that the performance of our solution is as good as for non-simultaneous mobility situation in terms of packet loss rate for low rate stream. On the other hand, the drawback is that some modifications to the current standard mSCTP are needed.
|
|
