TIME AND FREQUENCY CHARACTERISTIC OF 802.11AX

Wireless Local Area Network (WLAN) is a wireless communication system that connects two or more devices using radio frequency to form a local network (LAN). WLAN is used inside buildings (e.g., apartment, campus, train station). Unlike Ethernet, The first WLAN standard, namely IEEE 802.11b, was released in the 1990s. Maximum achievable data rate is 11 Mbps for 802.11b. The most recent version is 802.11ax with maximum throughput of 3.46 Gbps. This thesis reports network throughput, jitter, and delay performance of IEEE 802.11ax experimentally measured and analyzed under various conditions (SNR, window size and packet length). It also gives an empirical model to simulate the behavior of 802.11ax network throughput and jitter

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Novel Framework-Based Routing for Task-Adaptive Mobile Networks of Unmanned Aerial Vehicular

Many practical mobile ad hoc networks (MANET) have certain tasks instead of just randomly changing each node’s positions. We call such a mission-driven network task-adaptive MANET. A typical example is the flying ad hoc network (FANET) that consist of unmanned aerial vehicles (UAVs), which may change its network topology based on different task requirements. Each node moves to new locations based on the targeted network shape. To maintain a smooth topology transformation and minimize the position changes, during shape change, a MANET typically keeps the core-area nodes more stable and allows the nodes in the outer area of the network to move more drastically. This means the entire network has an approximate framework that reflects the relatively stable nodes located in the core area. This research proposes a new routing scheme to quickly identify the optimal end-to-end path using the network framework extraction result. The proposed routing scheme ensures that the packets flow along the more stable network regions (thus with a lower packet loss rate). The framework extraction scheme is based on network shape geometry analysis for the median axis recognition. Our work has contributions to three aspects of realistic network protocol applications: (1) Provides a network multi-center election and member control methodology with detailed protocol design. (2) Creates a stable and reliable MANET framework extraction algorithm which aids in routing table generation. (3) Real-time Unix system protocol implementation and emulation based on Common Open Research Emulator (CORE) + Extendable Mobile Ad-hoc Network Emulator (EMANE). Simulation results indicate that our framework-based routing scheme outperforms a popularly used mobility-adaptive MANET routing scheme—OLSR (optimized link state routing)—in terms of throughput and delay

Evaluation of Soil-Applied Chemical Fungicide and Biofungicide for Control of the <i>Fusarium</i> Wilt of Chrysanthemum and Their Effects on Rhizosphere Soil Microbiota

Chemical fungicides are a frequently used intervention for the control of the Fusarium wilt of chrysanthemum, but are no longer considered environmentally friendly. However, the biofungicides offer one of the best alternatives to reduce the use of chemical fungicides. In this study, a series of two-year greenhouse experiments were conducted to evaluate the soil-applied chemical fungicide (dazomet, DZ) and biofungicide (biocontrol agent combined with B. subtilis NCD-2, BF) for controlling the Fusarium wilt of chrysanthemum and its effects on rhizosphere soil microbiota. The results indicated that DZ and BF showed good control efficacy of Fusarium wilt of chrysanthemum in the two-year application evaluation. However, the DZ treatment significantly decreased the soil catalase and urease activities compared with the control, while BF showed a significant increase in bacterium/fungus ratios (B/F), soil urease and acid phosphatase activities. Abundances of potential plant pathogens F. oxysporum, Rhizoctonia zeae and Rhizoctonia solani were also lower, while potential plant-growth-promoting micro-organisms like the Rhizobiales bacterium and Mariniflexile sp. were higher in the BF treatment than in the control. Our findings suggested that the overall effect of the soil biota on chrysanthemum growth was more positive and stronger in the BF treatment than in the DZ treatment

Assessing the Influence of Fumigation and Bacillus Subtilis-Based Biofungicide on the Microbiome of Chrysanthemum Rhizosphere

Chrysanthemum is an important ornamental species in China. However, sustained monoculture often leads to a decline in soil quality, in particular to the build-up of pathogens. Fusarium wilt, a severe disease in chrysanthemum monoculture systems, was effectively controlled by fumigation and/or the application of a biofungicide in our previous study. However, the mechanisms underlying disease suppression remain elusive. Here, a series of greenhouse experiments were conducted to characterize the effect on the chrysanthemum rhizosphere microbiome of the fumigant dazomet (DZ) and of a biofungicide based on Bacillus subtilis NCD-2 (BF). The results indicated that the BF treatment increased bacterial diversity by 4.2%, while decreasing fungal diversity by 21.3%. After two seasons of BF treatment, the abundance of microbes associated with disease suppression such as Bacillus spp. and Trichoderma spp. increased 15.1-fold and 4.25-fold more than that of the control, while the pathogenic Fusarium oxysporum was decreased by 79.20% when compared to the control. Besides, the DZ treatment reduced both bacterial and fungal diversity 7.97% and 2.73% respectively, when compared with the control. The DZ treatment controlled Fusarium wilt disease and decreased the abundance of F. oxysporum in the first year, but the abundance of the F. oxysporum was 43.8% higher after two years in treated soil than in non-treated soil. Therefore, the application of BF has a great potential for the control of Fusarium wilt disease in chrysanthemum by changing soil microbiome structure and function