Densely deployed Wi Fi networks will play a crucial role in providing the capacity for next generation mobile internet. However, due to increasing interference, overlapped channels in Wi Fi networks and throughput eff...Densely deployed Wi Fi networks will play a crucial role in providing the capacity for next generation mobile internet. However, due to increasing interference, overlapped channels in Wi Fi networks and throughput efficiency degradation, densely deployed Wi Fi networks is not a guarantee to obtain higher throughput. An emergent challenge is how to effi ciently utilize scarce spectrum resources, by matching physical layer resources to traffi c demand. In this aspect, access control allocation strategies play a pivotal role but remain too coarse-grained. As a solution, this research proposes a flexible framework for fine-grained channel width adaptation and multi-channel access in Wi Fi networks. This approach, named SFCA(Subcarrier Fine-grained Channel Access), adopts DOFDM(Discontinuous Orthogonal Frequency Division Multiplexing) at the PHY layer. It allocates the frequency resource with a subcarrier granularity, which facilitates the channel width adaptation for multi-channel access and thus brings more fl exibility and higher frequency efficiency. The MAC layer uses a frequencytime domain backoff scheme, which combines the popular time-domain BEB scheme with a frequency-domain backoff to decrease access collision, resulting in higher access probability for the contending nodes. SFCA is compared with FICA(an established access scheme)showing significant outperformance. Finally we present results for next generation 802.11 ac Wi Fi networks.展开更多
The purpose of present work is a measurement of telomere length dynamic in proliferating cells in vitro by modified flow-FISH method. This method is a combination of two modifications： telomere length measurement in ...The purpose of present work is a measurement of telomere length dynamic in proliferating cells in vitro by modified flow-FISH method. This method is a combination of two modifications： telomere length measurement in differentiated cells by surface antigen and analysis of cells divisions＇ number by vital dye dilution. Lymphocytes were activated by anti-CD3 Abs with IL-2 presents and grown in vitro for 7 days. Cells division＇s number was measured by dilution of CFSE vital dye which cells were stained previously activation. For telomere length measurement we used flow-FISH method with Cy3 labeled telomere PNH probe. Using this method we evaluated the dynamic of telomere length in CD4＋ and CD8＋ T-cells after 7 days culturing in vitro and revealed the difference in telomere lengthening and shortening versus division rounds in cell subsets. In CD8＋ cells telomeres start lengthen on a second division with the maximum on 4th division round becoming more that 20% longer compared with undividing cells. In CD4＋ cells telomeres did not have any length peculiarities through all division rounds demonstrating different telomere regulation in subsets. This probably occurs due to the higher level ofhTERT protein expression in CD8＋ than CD4＋ cells do.展开更多
基金supported by National Natural Science Foundation of China(No.61471376)the 863 project(No.2014AA01A701)
文摘Densely deployed Wi Fi networks will play a crucial role in providing the capacity for next generation mobile internet. However, due to increasing interference, overlapped channels in Wi Fi networks and throughput efficiency degradation, densely deployed Wi Fi networks is not a guarantee to obtain higher throughput. An emergent challenge is how to effi ciently utilize scarce spectrum resources, by matching physical layer resources to traffi c demand. In this aspect, access control allocation strategies play a pivotal role but remain too coarse-grained. As a solution, this research proposes a flexible framework for fine-grained channel width adaptation and multi-channel access in Wi Fi networks. This approach, named SFCA(Subcarrier Fine-grained Channel Access), adopts DOFDM(Discontinuous Orthogonal Frequency Division Multiplexing) at the PHY layer. It allocates the frequency resource with a subcarrier granularity, which facilitates the channel width adaptation for multi-channel access and thus brings more fl exibility and higher frequency efficiency. The MAC layer uses a frequencytime domain backoff scheme, which combines the popular time-domain BEB scheme with a frequency-domain backoff to decrease access collision, resulting in higher access probability for the contending nodes. SFCA is compared with FICA(an established access scheme)showing significant outperformance. Finally we present results for next generation 802.11 ac Wi Fi networks.
文摘The purpose of present work is a measurement of telomere length dynamic in proliferating cells in vitro by modified flow-FISH method. This method is a combination of two modifications： telomere length measurement in differentiated cells by surface antigen and analysis of cells divisions＇ number by vital dye dilution. Lymphocytes were activated by anti-CD3 Abs with IL-2 presents and grown in vitro for 7 days. Cells division＇s number was measured by dilution of CFSE vital dye which cells were stained previously activation. For telomere length measurement we used flow-FISH method with Cy3 labeled telomere PNH probe. Using this method we evaluated the dynamic of telomere length in CD4＋ and CD8＋ T-cells after 7 days culturing in vitro and revealed the difference in telomere lengthening and shortening versus division rounds in cell subsets. In CD8＋ cells telomeres start lengthen on a second division with the maximum on 4th division round becoming more that 20% longer compared with undividing cells. In CD4＋ cells telomeres did not have any length peculiarities through all division rounds demonstrating different telomere regulation in subsets. This probably occurs due to the higher level ofhTERT protein expression in CD8＋ than CD4＋ cells do.
