| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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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.
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| 2. |
- Kang, Du Ho, et al.
(författare)
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Attainable User Throughput by Dense Wi-FiDeployment at 5 GHz
- 2013
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Ingår i: 2013 IEEE 24th International Symposium on Personal Indoor and Mobile Radio Communications (PIMRC). - : IEEE conference proceedings. - 9781467362351 ; , s. 3418-3422
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Konferensbidrag (refereegranskat)abstract
- Most of currently deployed Wi-Fi networks use the IEEE 802.11b/g standard and operate in 2.4 GHz ISMband. As mobile traffic demand rapidly increases, significant Wi-Fi deployment in the still very lightly used 5 GHz band is anticipated. In combination with the recent PHY amendments, e.g., 802.11ac, such Wi-Fi in many settings emerges as a strong competitor to small cellular deployment. In this paper, we aim to quantify what total capacity and which data rates per user can be supported by high-density, the state-of-the-art 5 GHz Wi-Fi deployment. Unlike previous studies, we consider the effect of densification by explicitly modeling the different level of interference among access points for office-type scenarios with various internal wall losses. Although abundant spectrum availability at 5 GHz may compensate for system inefficiency caused by carrier sensing and contention, we find that there is a capacity limit. This capacity limit depends on propagation environments and is especially low in 'open' environments or environments with low wall losses. To operate at capacities above this limit, cellular systems with their more advanced interference mitigation techniques are required.
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| 3. |
- Kang, Du Ho, et al.
(författare)
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Cooperation and Competition between Wireless Networks in Shared Spectrum
- 2011
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Ingår i: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC). - New York : IEEE. - 9781457713484 ; , s. 284-288
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Konferensbidrag (refereegranskat)abstract
- As the regulation in wireless communications is moving toward a more flexible and efficient way of managing radio spectrum, it is envisaged that multiple small-sized cellular networks owned by different operators will operate in close vicinity on shared spectrum. This brings a new interference environment where a cell is interfered by not only base stations in own network but also those in other networks. These networks may compete for their own utilities in a selfish manner or cooperate in order to minimize the mutual interference. Since a cooperation between the networks requires a business-wise agreement or extra infrastructure cost, the operators have to identify how much they will benefit from the cooperation. In this paper, we compare the effects of competition and cooperation between the cellular networks. The competition and cooperation are modeled as a transmit power control in downlink. It is observed that the cooperation in an average sense gives better network utility. However, as the network size increases, the cooperation gain diminishes significantly. Furthermore, the marginal separation of network deployments, e.g., indoor deployments in adjacent buildings, can notably shrink the cooperation incentive.
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| 4. |
- Kang, Du Ho, et al.
(författare)
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Cost and Feasibility Analysis of Self-deployed Cellular Networks
- 2011
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Ingår i: 2011 IEEE 22nd International Symposium On Personal Indoor And Mobile Radio Communications (PIMRC). - New York : IEEE. - 9781457713460 ; , s. 248-252
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Konferensbidrag (refereegranskat)abstract
- A self-deployed network is considered to be one of cost-efficient deployment solutions by skipping an expensive network planning process. However, it may result in the serious degradation of capacity or the infeasibility of coverage constraint due to the rise of interference although radio adaptation techniques are employed. Therefore, deployment decision makers, e.g., operators, need to identify when and where the self-deployed network is feasible and economical compared with the planned network. For this, we estimate the average network throughput of the self-deployed network subject to a coverage constraint and compare it with the planned network. Three distinct regions of self-deployment are identified where different deployment strategies are required: infeasible, cost-effective, and uneconomical. We evaluate how the regions alter according to different channel environments and make suggestions for economical deployment.
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| 5. |
- Kang, Du Ho, et al.
(författare)
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High capacity indoor and hotspot wireless systems in shared spectrum : A techno-economic analysis
- 2013
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Ingår i: IEEE Communications Magazine. - 0163-6804 .- 1558-1896. ; 51:12, s. 102-109
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Tidskriftsartikel (refereegranskat)abstract
- Predictions for wireless and mobile Internet access suggest an exponential traffic increase, particularly in in-building environments. Non-traditional actors such as facility owners have a growing interest in deploying and operating their own indoor networks to fulfill the capacity demand. Such local operators will need spectrum sharing with neighboring networks because they are not likely to have their own dedicated spectrum. Management of internetwork interference then becomes a key issue for high capacity provision. Tight operator-wise cooperation provides superior performance, but at the expense of high infrastructure cost and business-related impairments. Limited coordination, on the other hand, causes harmful interference between operators, which in turn will require even denser networks. In this article, we propose a techno-economic analysis framework for investigating and comparing indoor operator strategies. We refine a traditional network cost model by introducing new inter-operator cost factors. Then we present a numerical example to demonstrate how the proposed framework can help us to compare different operator strategies. Finally, we suggest areas for future research.
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| 6. |
- Kang, Du Ho, et al.
(författare)
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Is Multicell Interference Coordination Worthwhile in Indoor Wireless Broadband Systems?
- 2012
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Ingår i: 2012 IEEE Global Communications Conference (GLOBECOM). - : IEEE. - 9781467309219 ; , s. 4255-4260
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Konferensbidrag (refereegranskat)abstract
- The rapid growth in demand for mobile and nomadic wireless access forces the use of more and more base stations (BSs). In such dense networks, various techniques for multicell interference coordination have been investigated. However, whether or not the interference coordination provides cost benefit compared with a loosely coordinated system is not obvious because the tight coordination at PHY-layer is likely to need an expensive high-speed backbone infrastructure. In this paper, we assess the worthiness of the tight interference coordination, referred to as coordination gain, in various indoor environments. We compare a hypothetical interference-free system as an upper bound with a simple interference-limited system opportunistically avoiding interference. The range of possible coordination gain is examined for various wall losses, path loss exponents, building shapes, and deployment density. Results show that substantial gain can be achieved in dense deployment at open areas with low path loss exponent, e.g., lightly furnished offices partitioned with soft walls. Nevertheless, the coordination gain significantly drops in the presence of marginal wall loss regardless of the other environmental factors.
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| 7. |
- Kang, Du Ho, et al.
(författare)
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Operator competition with asymmetric strategies in shared spectrum
- 2012
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Ingår i: 2012 IEEE Wireless Communications and Networking Conference, WCNC. - : IEEE Communications Society. - 9781467304375 ; , s. 3183-3187
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Konferensbidrag (refereegranskat)abstract
- As the regulation in wireless communications is moving toward a more flexible and efficient way of managing radio spectrum, it is envisaged that multiple small-sized cellular networks owned by different operators, e.g., facility owners or local operators, will operate in close vicinity on shared spectrum. In this environment, the networks may compete for their own utilities in a selfish manner with giving harmful internetwork interference to competitors. In practice, it is not so unusual that each operator has different fairness criteria or quality of service (QoS) strategies by employing distinct objective functions from competitors. Particularly, we in this paper study power control competition between two networks with the sum of rates (SR) and the minimum rate (MR) as their objective functions, respectively. By exploring Nash equilibria, we identify that the MR network benefits from the objective asymmetry thanks to the adaptability of its competitor, i.e., no constraint in the SR objective. On the other hand, the SR network takes disadvantage due to the fairness requirement reflected in the MR objective of its competitor. However, such asymmetry effects in competition becomes negligible with marginal network separation, e.g., indoor deployment in adjacent buildings. Additionally, we identify cooperation potential with the proper choice of a common objective function although the asymmetric objectives are difficult to be aligned.
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| 8. |
- Kang, Du Ho, et al.
(författare)
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The Validity of Unlicensed Spectrum for Future Local Highcapacity Services
- 2013
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Konferensbidrag (refereegranskat)abstract
- Unlicensed spectrum indeed initiates high-data rate wireless services with the combination of the great success of Wi-Fi technology. Interestingly, the local high data rate services are deployed and invested by non-traditional local actors, e.g., facility owners who have local fixed line infrastructure. Motivated by the great success of the Wi-Fi eco-system, there are growing interests from various regulatory initiatives on short-range indoor shared spectrum access to continuously foster new business innovations and local investment by new players. Despite of flexible spectrum access and almost no regulatory management overhead, it is still not so clear that the traditional unlicensed approach can work for future high-capacity services where require extremely denser deployment than today. In this paper, we aim to discuss the validity of the traditional unlicensed approach for the new local operators in an economic aspect. We evaluate the required deployment cost of conventional Wi-Fi system and compare it with a hypothetical cellular-like system with marginal regulatory coordination. We found that the traditional node-level etiquettes in unlicensed band work as system design constraints, leading to too conservative full distributed systems. Although the current unlicensed band approach is the lowest cost solution for relatively low-capacity services, it may not be work at future high-capacity provisioning. Thus, regulations need to be designed to allow more coordinated systems such as cellular-like technologies with certain inter-network regulation.
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