Noise reduction in ultra-low light digital holographic microscopy using neural networks

Live cell imaging is challenging because the difficult balance of maintaining both cell viability and high signal to noise ratio throughout the entire imaging duration. Label free quantitative light microscopy techniques are powerful tools to image the volumetric activities in living cellular and sub-cellular biological systems, however there are minimal ways to identify phototoxicity. In this paper, we investigate the use of neural network to restore quantitative digital hologram micrographs at ultra-low light levels down to 0.06 /2 which approximately two orders of magnitude lower than sunlight. By developing an adaptive image restoration method specifically tailored for digital holograms, we demonstrated the 2x improvement in SSIM over existing denoising methods. This demonstration could open up new avenues for high resolution holographic microscopy using deep ultraviolet coherent sources and achieve high-resolution imaging with ultralow light illuminatio

Dynamics Analysis of Neuron Bursting under the Modulation of Periodic Stimulation

A nonsmooth neuron model with periodic excitation which can reproduce spiking and bursting behavior of cortical neurons is investigated in this paper. Based on nonsmooth bifurcation analysis, the mechanism of the bursting behavior induced by slow-changing periodical stimulation as well as the associated evolution with the variation of the stimulation is explored. The modulating character of the external excitation and the effect of the bifurcation occurring at the switching boundary of the vector field are presented

Quantitative modelling of amino acid transport and homeostasis in mammalian cells

Homeostasis is one of the fundamental concepts in physiology. Despite remarkable progress in our molecular understanding of amino acid transport, metabolism and signaling, it remains unclear by what mechanisms cytosolic amino acid concentrations are maintained. We propose that amino acid transporters are the primary determinants of intracellular amino acid levels. We show that a cell’s endowment with amino acid transporters can be deconvoluted experimentally and used this data to computationally simulate amino acid translocation across the plasma membrane. Transport simulation generates cytosolic amino acid concentrations that are close to those observed in vitro. Perturbations of the system are replicated in silico and can be applied to systems where only transcriptomic data are available. This work explains amino acid homeostasis at the systems-level, through a combination of secondary active transporters, functionally acting as loaders, harmonizers and controller transporters to generate a stable equilibrium of all amino acid concentrations

Holo-UNet: hologram-to-hologram neural network restoration for high fidelity low light quantitative phase imaging of live cells

Intensity shot noise in digital holograms distorts the quality of the phase images after phase retrieval, limiting the usefulness of quantitative phase microscopy (QPM) systems in long term live cell imaging. In this paper, we devise a hologram-to-hologram neural network, Holo-UNet, that restores high quality digital holograms under high shot noise conditions (sub-mW/cm2 intensities) at high acquisition rates (sub-milliseconds). In comparison to current phase recovery methods, Holo-UNet denoises the recorded hologram, and so prevents shot noise from propagating through the phase retrieval step that in turn adversely affects phase and intensity images. Holo-UNet was tested on 2 independent QPM systems without any adjustment to the hardware setting. In both cases, Holo-UNet outperformed existing phase recovery and block-matching techniques by ∼ 1.8 folds in phase fidelity as measured by SSIM. Holo-UNet is immediately applicable to a wide range of other high-speed interferometric phase imaging techniques. The network paves the way towards the expansion of high-speed low light QPM biological imaging with minimal dependence on hardware constraints.Australian Research Council (DE160100843, DP190100039, DP200100364

Microscopic Mechanism of Cement Improving the Strength of Lime-Fly Ash-Stabilized Yellow River Alluvial Silt

Silt is a kind of soil with poor engineering performance. Lime-fly ash- (LF-) stabilized silt has the problem of low early strength. In this study, it is aimed to investigate the effect of cement on improving the strength of LF-stabilized silt and reveal the microscopic mechanism. A fixed percentage of LF (18%) plus different percentages of cement (0%, 2%, 4%, and 6%) were mixed with Yellow River alluvial silt (YRAS). Soil samples for tests were artificially made by compaction in the laboratory. Unconfined compressive strength (UCS) tests were performed on soil samples cured for 7 d, 28 d, 60 d, and 90 d. Scanning electron microscope (SEM) tests, energy dispersive X-ray spectroscopy (EDS) tests, and mercury intrusion porosimetry (MIP) tests were performed on soil samples cured for 7 d and 28 d. UCS results showed that the early strength of LF-stabilized YRAS developed significantly after adding cement. UCS also increased with the increase in cement content and curing time. SEM results revealed the differences in microstructure of LF-stabilized YRAS before and after adding cement. Before adding cement, the main microstructure characteristics included small soil particles, large number of pores, and loose particle arrangement. After adding cement, the main microstructure characteristics included large bonded particles, small number of pores, and dense particle arrangement. The EDS results showed that, after curing for 28 d, the elements of gels in stabilized YRAS had changed, mainly including appearance of C and a significant increase of Ca. MIP results showed that the pores with a size of 1 μm∼10 μm accounted for the largest proportion in stabilized YRAS. The product (mainly C-S-H) of cement hydration mainly filled the pores with a size larger than 10 μm at the early stage. Combining strength results and microresults, the micromechanism of cement improving the strength of LF-stabilized YRAS was discussed

A Systematic Study on Berthing Capacity Assessment of Sanya Yazhou Fishing Port by Typhoon Prediction Model

This paper sheds light on the effect of combination modes on the evaluation of berthing capacity for Sanya Yazhou Fishing Port (SYFP) under hypothetical typhoon conditions. By statistically analysing the maximum probability of moving speeds and directions of historical typhoons passing through the fishing port, the representative typhoon path was determined with the nonparametric regression method. The designed typhoon wind fields of levels 12–17 were generated based on Holland’s parametric wind model. Then, the MIKE 21 BW model was used to obtain the high-precision wave distribution in the fishing port. The boundary conditions (significant wave height and peak period) of the MIKE 21 BW model were calculated by combining the MIKE 21 SW model with the designed typhoon wind fields. In SYFP, ships usually adopt the modes of multi-ship side-by-side and single anchor mooring during typhoons. In fair weather, approximately 158 vessels can be berthed if they are all large ones, while approximately 735 vessels can be moored if they are all small ones. However, with an increase in typhoon levels, the anchoring area for small vessels decreases. From the perspective of wave distribution in the fishing port, the number of large vessels moored was hardly affected by typhoons. This can be attributed to the breakwater, which significantly decreases the large wave height in the fishing port. Finally, a study on the framework of a method for hazard assessment of berthing capacity in the coming typhoon-driven storm waves was set up

A Systematic Study on Berthing Capacity Assessment of Sanya Yazhou Fishing Port by Typhoon Prediction Model

This paper sheds light on the effect of combination modes on the evaluation of berthing capacity for Sanya Yazhou Fishing Port (SYFP) under hypothetical typhoon conditions. By statistically analysing the maximum probability of moving speeds and directions of historical typhoons passing through the fishing port, the representative typhoon path was determined with the nonparametric regression method. The designed typhoon wind fields of levels 12–17 were generated based on Holland’s parametric wind model. Then, the MIKE 21 BW model was used to obtain the high-precision wave distribution in the fishing port. The boundary conditions (significant wave height and peak period) of the MIKE 21 BW model were calculated by combining the MIKE 21 SW model with the designed typhoon wind fields. In SYFP, ships usually adopt the modes of multi-ship side-by-side and single anchor mooring during typhoons. In fair weather, approximately 158 vessels can be berthed if they are all large ones, while approximately 735 vessels can be moored if they are all small ones. However, with an increase in typhoon levels, the anchoring area for small vessels decreases. From the perspective of wave distribution in the fishing port, the number of large vessels moored was hardly affected by typhoons. This can be attributed to the breakwater, which significantly decreases the large wave height in the fishing port. Finally, a study on the framework of a method for hazard assessment of berthing capacity in the coming typhoon-driven storm waves was set up

Field test research on the application of double-liquid curing agent in deep mixing columns

Cement is an important building material with high energy consumption and high emission, while energy conservation and emission reduction has been the consensus over the world in the background of the global climate warming. Aiming at the problems of large cement consumption and long construction period of deep mixing column, a double-liquid curing agent composed of low thickness cement slurry and sodium silicate solution is proposed to replace cement slurry in deep mixing columns. The installation equipment is modified to adapt to the double-liquid curing agent. The effect of the double-liquid curing agent is researched through field​ tests, which verify the environmental and economic benefits in cement saving and construction accelerating. The double-liquid curing agent for deep mixing columns has great promotion potential