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MySQL Cluster Manager uses the XCom (a Paxos variant) as its consensus protocol. Before XCom allows a new message to be delivered, it requires a majority vote by all agents to decide who can send the next message. This majority is referred to as a "quorum." In general, a simple majority of the agents (that is, half of the total number of agents plus one) constitutes a quorum. So, the quorum for a cluster with 4 agents is 3, and for 6 agents is 4, and so on. Here are some special cases:
Bacteria were thought to be single-celled individuals and not related to each other in previous studies. Until the 1970s, quorum sensing (QS) was first proposed when Miller and Nealson discovered bacterial cell interactions while studying Streptococcus pneumoniae and Vibrio fischeri (Nealson & Hastins 1979; Miller & Bassler 2000). Bacterial QS refers to the bacteria release the signal molecules in the environment, and through sensing signal molecule concentration to induce the expression of related genes in the cytoplasm of bacteria. In this process, the ecological relationship of flora and physiological behavior are regulated, showing physiological functions and regulatory mechanisms that cannot be realized by a single bacterium, such as regulating the formation of biofilm, producing antibiotics and secondary metabolites, etc. (Waters & Bassler 2005; Shrout & Nerenberg 2012).
MBR membrane biofouling is the result of the interaction between membrane and sludge. Bacteria form biofilm on the membrane surface to block the pores of membrane material, leading to the decrease of membrane flux and water yield. Therefore, membrane components need to be cleaned, but frequent cleaning will cause deterioration of membrane performance (Yeon et al. 2009; Feng et al. 2013). Based on the importance of QS system for Gram-negative bacteria, it is not surprising that some hosts or competing bacteria would benefit from inhibiting QS activity. The technique blocking QS system and inhibiting gene expression mediating bacterial behaviors is called quorum quenching (QQ), which is considered to be an ideal approach for membrane biofouling control (Malaeb et al. 2013). QS and QQ are two antagonistic processes that are common in WWT. The phenomenon of AHL-based QS or QQ in biological wastewater treatment can be determined by the concentration of AHL in bacteria, while the effective AHL concentration is affected by extracellular environmental factors of bacteria (Platt & Fuqua 2010; Maddela et al. 2019). Apparently, the environment is of great significance to the AHL-based QS and QQ in bacteria. The shorter acyl-chains of AHL signal is favorable for hydrolysis at alkaline pH, and AHL signals require at least four carbons acyl chain to keep stable under pH conditions encountered by most bacteria (Yates et al. 2002; Decho et al. 2009). AHLs with longer acyl chains (>C12) are more resistant to alkaline lysis (Decho et al. 2010). Studies have also demonstrated that the AHL production in the cellular environment is highly dependent on the growth temperature and accompanied by phenotypic changes (Kirwan et al. 2006; Kimes et al. 2012). In addition, operational conditions can be profoundly important for bacterial AHL-based QS. The increase of SRT in MBR would increase the QQ effect in the system, while the QS would decrease accordingly (Yu et al. 2016). Many bacteria have been identified to possess QS or QQ activity in biological WWT (Table 2). The QQ approach disrupts the formation of biofilm at the source, thus provides a new idea to solve the biofouling in MBRs.
Compared with AGS, the quorum sensing of anaerobic granular sludge (AnGS) is more complex and has not yet formed a relatively complete regulatory mechanism. In AnGS system, the research focused on AHL, AI-2 and DSF. The main AHLs was C4-HSL, accounting for more than 95% of total AHLs, and the concentration of total AHLs was 5.72 1.56 pM/L (Ding et al. 2015b). With the formation of AnGS, the content of C4-HSL decreased significantly. The content of AI-2 was relatively stable in the system, with relative value of 0.58 0.06 (relative light unit: the intensity of the sample at 490 nm compared to that of the negative control) (Song et al. 2014; Servinsky et al. 2016; Zhao et al. 2018). The concentration of DSF is not stable in the system, whose initial concentration was 0.66 0.06 nM/L and then increased to 1.76 0.18 nM/L reaching the peaks (Wang et al. 2004).
Adtran, Inc., (NASDAQ: ADTN),today announced that it has achieved a quorum for the special meeting of stockholders to be held at 10:30 a.m. Central Standard Time on Thursday, January 6, 2022, in connection with its proposed business combination with ADVA Optical Networking SE. Adtran stockholders who have submitted proxies to date have overwhelmingly voted in support of the business combination, as well as for the other proposals to be voted at the special meeting of stockholders. While stockholders are permitted to change or revoke their proxies before or during the special meeting of stockholders, it is now anticipated that the business combination and other proposals will be approved.
The Johnson & Johnson award will enable Blackwell to test such laboratory compounds directly within living systems, and tease apart bacterial relationships in both harmful and beneficial bacterial colonies that sometimes comprise multiple bacterial species. Ultimately, the work should help to understand the impact of quorum sensing on animals and plants that bacteria invade, Blackwell says. 041b061a72