The standard IEEE 8 0 2 . 3~ is introduced to manage XONXOFF flow control mechanism in full duplex gigabit Ethernet. In a IEEE 8 0 2 . 3~ network, a downstream station can send XOFF messages to upstream stations to stop them from sending data until a specified time slot has passed or the downstream station receives a XON message. The development of efficient XONXOFF flow control mechanism is still an active research topic. This paper describes F L O M , a IEEE 802.3~ XON/XOFF control scheme with proposed modifications. It introduces a hop-by-hop backpressure control based on flow rate in order to fully utilize the performance of large scale LANs. The control strategy of FLORAX is based on applying backpressure depending on the bandwidth of the flows, where flow is defined to be a source -destination MAC address pair. FLORAXallows the use of Service Level Agreement (SLA) for quality of service. FLORAX is fair in the sense that it distributes the bandwidth among flows during congestion. The simulation study is performed to compare the performance of earlier approaches with the FLORAX. Experiment results demonstrate that FLORAX achieves fair bandwidth distribution for the duration of transmission, efficient use of link bandwidth, and reduction in packet loss.

Cd stress can cause severe damage to the chloroplast structure and plant function. The chloroplast stay-green gene (SGR2) is senescence-inducible and has several important functions such as regulating senescence, responding to abiotic stress, and regulating seed and fruit ripening. The SlSGR2 gene was cloned from the tomato “Hongluocheng” (full-length of 819 bp encoding 272 amino acids). Subcellular localization prediction and laser confocal observation revealed that the SlSGR2 protein was localized to the chloroplast of A. thaliana protoplasts. A qRT-PCR analysis suggested that the SlSGR2 gene was upregulated by different Cd concentrations and that the gene expression was significantly upregulated in tomato roots and leaves under 50 μM CdCl2 treatment. The pCAMBIA2300-SlSGR2 overexpression constructs were introduced into wild-type Arabidopsis plants via Agrobacterium-mediated transformation. Homozygous mutant lines of sgr2 were identified using the three-primer method. The growth of SlSGR2-overexpressed lines under Cd stress was significantly better than that of WT and sgr2. The chlorophyll, SOD, POD, and CAT contents of OE4-1 and OE4-2 were significantly higher than those of WT and sgr2 while the MDA content was significantly lower than other lines under cadmium stress. This study showed that the SlSGR2 gene is involved in Cd-induced plant senescence and is a negative regulator of plant chlorophyll degradation.

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