The Poisson Distribution Is Applied to Improve the Estimation of Individual Cell and Micropopulation Lag Phases

Many articles dealing with individual cell lag phase determination assume that growth, when observed, comes from one cell. This assumption is not in agreement with the Poisson distribution, which uses the probability of growth in a sample to predict how many samples contain one, two, or some other number of cells. This article analyses and compares different approaches to improve the accuracy of lag phase estimation of individual cells and micropopulations. It argues that if the highest initial load, as predicted by the Poisson distribution, is assigned to the sample with the shortest lag phase, the second highest to the sample with the second shortest lag phase and so on, the resulting lag phase distributions would be more accurate. This study also proposes the use of a robust test, permutation test, to compare lag phase distributions obtained in different situations.

Mitochondrial superoxide anions induced by exogenous oxidative stress determine tumor cell fate: an individual cell-based study

Objective: Reactive oxygen species(ROS) are involved in a variety of biological phenomena and serve both deleterious and beneficial roles. ROS quantification and assessment of reaction networks are desirable but difficult because of their short half-life and high reactivity. Here, we describe a pro-oxidative model in a single human lung carcinoma SPC-A-1 cell that was created by application of extracellular H2O2 stimuli. Methods: Modified microfluidics and imaging techniques were used to determine O2·- levels and construct an O2^·- reaction network. To elucidate the consequences of increased O2^·- input, the mitochondria were given a central role in the oxidative stress mode, by manipulating mitochondria-interrelated cytosolic Ca2+ levels, mitochondrial Ca^2+ uptake, auto-amplification of intracellular ROS and the intrinsic apoptotic pathway. Results and conclusions: Results from a modified microchip demonstrated that 1 mmol/L H·-2 O2 induced a rapid increase in cellular O2 levels(>27 vs.>406 amol in 20 min), leading to increased cellular oxidizing power(evaluated by ROS levels) and decreased reducing power(evaluated by glutathione(GSH) levels). In addition, we examined the dynamics of cytosolic Ca^2+ and mitochondrial Ca^2+ by confocal laser scanning microscopy and confirmed that Ca^2+ stores in the endoplasmic reticulum were the primary source of H2O2-induced cytosolic Ca^2+ bursts. It is clear that mitochondria have pivotal roles in determining how exogenous oxidative stress affects cell fate. The stress response involves the transfer of Ca^2+ signals between organelles,ROS auto-amplification, mitochondrial dysfunction, and a caspase-dependent apoptotic pathway.

Radiation Damage Analysis of Individual Subcells for GaInP/GaAs/Ge Solar Cells Using Photoluminescence Measurements

The radiation damage of three individual subcells for GalnP/GaAs//Ge triple-junction solar cells irradiated with electrons and protons is investigated using photoluminescence （PL） measurements. The PL spectra of each subcell are obtained using different excitation lasers. The PL intensity has a fast degradation after irradiation, and decreases as the displacement damage dose increases. Furthermore, the normalized PL intensity varying with the displacement damage dose is analyzed in detail, and then the lifetime damage coefficients of the recombination centers for GaInP top-cell, GaAs mid-cell and Ge bottom-cell of the triple-junction solar cells are determined from the PL radiative efficiency.

Modeling and characterization of novel magnetorheological(MR) cell with individual currents

Magnetorheological(MR) cell with multi-coil was designed to enlarge the range of controllable transmission torque by increasing the effective length. Individual input current was proposed to maximize its potential for reducing power consumption and generating large yield stress. Finite element analysis was performed to analyze magnetic field distribution, based on which a prototype MR cell was fabricated and tested to investigate the performance of various combinations of individual input currents. A good correlation was identified between experimental results and FEA predications. The results show that the power consumption can be reduced to 42.4%, maintaining large transmission torque, by distributing the total current(2 A) to three individual magnetic coils. In addition, optimal results of four input currents considering a multi-objective function are obtained by changing the weighting factor λ. The advantage of this design, such as lower power consumption and more control flexibility, makes it more competitive in engineering applications that require large energy consumption.