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

Determination Of Ground Structure Using Microtremor Array Method

Ground structure characteristic is an important parameter in seismic site effect evaluation for earthquake structural design. Many geophysical methods can be used to estimate ground structure. The best field measurement option that requires least field effort and yet producing accurate estimation is the main concern of this study. This study applies microtremor array observation method to investigate the accuracy of VS profile estimated using Spatial Autocorrelation (SPAC) and Centerless Circular Array (CCA) methods of various array radii. Based on VS profile obtained, the effect of considering sediment thickness of more than 30m on ground classification is investigated. Microtremor array observation was conducted at a total of nine sites in Kuala Lumpur and Penang with large (10m radius and above), medium (5m radius) and small (1m radius) array. When using SPAC method, larger array gives better VS profile estimation. When using CCA method, medium array gives better estimation among three array sizes. CCA method gives better estimation as compared to SPAC method when medium array is used in observation. Thus, CCA method is more favourable in term of fieldwork efficiency. Out of five sites with sediment thickness more than 30m, four sites exhibit ground type changes by reducing one to two classes and the other one remains unchanged. Although the ground type remains unchanged, but the acceleration response increases. These changes in ground type have affected low to medium rise buildings within the fundamental periods of 0.1s to 1.0s significantly because the acceleration response increases drastically when sediment thickness more than 30m is considered

Introducing a New Method for Ground Structure Estimation using Microtremor Array Observation Technique

Ground structure characteristic is an important parameter in seismic site effect evaluation for earthquake structural design. Many geophysical methods can be used to estimate ground structure. The best field measurement option that requires least field effort and yet producing accurate estimation is the main concern of this study. This study applies microtremor array observation method to investigate the accuracy of dispersion curve estimated using Centerless Circular Array (CCA) methods of 5m radius. The dispersion curve observed was assessed by comparing to theoretical dispersion curve generated from proposed shear wave velocity (VS) profile of sites. The observed dispersion curve shows good agreement with theoretical dispersion curve over a wide frequency range, which is ranging from 3 - 10 Hz. This segment of dispersion curve can be utilized to estimate ground structure by means of inversion of dispersion curve. CCA method is capable to be used to estimate ground structure in term of VS profile

Introducing a New Method for Ground Structure Estimation using Microtremor Array Observation Technique

Ground structure characteristic is an important parameter in seismic site effect evaluation for earthquake structural design. Many geophysical methods can be used to estimate ground structure. The best field measurement option that requires least field effort and yet producing accurate estimation is the main concern of this study. This study applies microtremor array observation method to investigate the accuracy of dispersion curve estimated using Centerless Circular Array (CCA) methods of 5m radius. The dispersion curve observed was assessed by comparing to theoretical dispersion curve generated from proposed shear wave velocity (VS) profile of sites. The observed dispersion curve shows good agreement with theoretical dispersion curve over a wide frequency range, which is ranging from 3 - 10 Hz. This segment of dispersion curve can be utilized to estimate ground structure by means of inversion of dispersion curve. CCA method is capable to be used to estimate ground structure in term of VS profile

Estimation of Ground Structure at USM using Microtremor Observation Technique

Determination of ground structure is important for seismic hazard analysis and earthquake design of structures. Different types of ground structure at site, depending on its profile of shear-wave velocity, will amplify seismic wave at different extents. Therefore, structures should be designed accordingly to withstand the expected surface ground motion considering seismic site amplification. Microtremor observations were conducted in this study due to its simplicity, less field effort and economy. Field measurement was carried out at two sites at Universiti Sains Malaysia Engineering Campus where the actual soil profiles were known from the existing borelog data. Two sizes of circular array formed by three three-component velocity sensors along the circumference of circle and a three-component velocity sensor at the center for each array were performed. The recorded data were analysed using Spatial Autocorrelation (SPAC) method. Shear wave velocity profile for the site was then estimated through inversion of phase velocity. To produce convincing estimation of ground structure, the horizontal to vertical (H/V) spectra at the center of the circular array was compared with the computed ellipticity of the fundamental mode of Rayleigh wave. The obtained results were also compared with the borelog data. The accuracy for the estimation of ground structure based on various microtremor array sizes and analysis techniques was assessed

Estimation of Ground Structure at USM using Microtremor Observation Technique

Determination of ground structure is important for seismic hazard analysis and earthquake design of structures. Different types of ground structure at site, depending on its profile of shear-wave velocity, will amplify seismic wave at different extents. Therefore, structures should be designed accordingly to withstand the expected surface ground motion considering seismic site amplification. Microtremor observations were conducted in this study due to its simplicity, less field effort and economy. Field measurement was carried out at two sites at Universiti Sains Malaysia Engineering Campus where the actual soil profiles were known from the existing borelog data. Two sizes of circular array formed by three three-component velocity sensors along the circumference of circle and a three-component velocity sensor at the center for each array were performed. The recorded data were analysed using Spatial Autocorrelation (SPAC) method. Shear wave velocity profile for the site was then estimated through inversion of phase velocity. To produce convincing estimation of ground structure, the horizontal to vertical (H/V) spectra at the center of the circular array was compared with the computed ellipticity of the fundamental mode of Rayleigh wave. The obtained results were also compared with the borelog data. The accuracy for the estimation of ground structure based on various microtremor array sizes and analysis techniques was assessed

Genetic risk of extranodal natural killer T-cell lymphoma: a genome-wide association study in multiple populations

10.1016/s1470-2045(19)30799-5The Lancet Oncolog