Ca2+ is one of the most versatile and widely-used second-messenger molecules, and plays a pivotal role in neurotransmission, muscle contraction, gene expression, and a variety of other intracellular ...processes. Many cells have developed sophisticated intracellular signal transduction pathways that involve different proteins modulated by Ca2+ for communication between intracellular compartments or neighboring cells. The astrocytes, which are the dominant glial cell type, had been regarded as maintenance and support cells for neurons until recent years. But, with a series of discoveries of propagating calcium waves in networks of astrocytes, people began to believe that astrocytes modulate neural network activities. One example of the cross-talk is reflected in the observed ATP-mediated calcium waves, which demonstrate the coupling between intracellular calcium dynamics and cell-cell communication via the extracellular space. In this thesis, a model of glutamate-induced Ca2+ oscillations in astrocytes will be studied. To study temporal aspect, a system of ODE will be derived and the derived full ODE model will be reduced to a lower dimensional system of ODE by nondimensional analysis. Using the temporal model, we will attempt to understand recent observations on the different types of intracellular Ca2+ response patterns in terms of PKC and PLC that determine the intracellular level of IP3. Following this, we will develop a PDE model for wave propagation between astrocytes from the reduced ODE system. To study how the different configuartions of geometry influence the Ca2+i wave propagation, the PDE model was solved on two different geometries: a retangular array of cells for astrocytes in vitro and a complex geometry mimicking astrocyte network in vivo. The PDE model demonstrates that temporal Ca2+ i response patterns in cells are different from one cell to another, and even more Ca2+i response patterns evolve from one type to another as Ca2+i wave propagates. Also, the spatial patterns of Ca2+i wave propagations are different when IP3 and/or ATP are/is mediating messenger(s). Finally, the effects of extracellular space volume on ATP and Ca2+ i waves propagation and regenertivity of ATP release will be studied.
There is an old adage that says “To see is to believe,” and it still seems to be true in many fields of biology. For an experimental validation of hypotheses, modern biology takes advantage of ...various fluorescence-based techniques (fluorescence microscopy, digital image analysis) for visualization and quantification. Fluorescence Recovery after Photobleaching (FRAP), a widely used fluorescence-based technique to visualize and quantify the diffusion of fluorescently tagged proteins, is one good example. The first observation of fluorescence was made by Sir John Frederick William Herschel (1845) from a quinine solution, and the concept of fluorescence was first named after fluorite by Sir George G. Stokes (1857). On a microscopic scale, fluorescence was first observed by August K?ler (1904), who discovered that a biological tissue could autofluoresce under ultraviolet light irradiation. Later, it became popular in the biological field after M. Haitinger (1933) succeeded in staining histological specimens with fluorescent dyes for the first time, which is called the technique of secondary fluorescence, distinguishing it from autofluorescent tissue previously observed by M. Haitinger. Haitinger and others extended the application of the technique of secondary fluorescence to stain not only specific tissues but also bacteria, or other pathogens that are not autofluorescent 1. Although the technique of secondary fluorescence demonstrated that nonfluorescent cells can be made fluorescent, it was a nonspecific staining technique. The breakthrough in a specific immunofluorescence staining technique was provided by Albert Coons in 1941 by attaching a fluorescent dye to an antibody 2. Later, Coons and N.H. Kaplan developed the fluorescein isothiocyanate (FITC) immunofluorescence technique 3.
In this paper, we consider the power splitting relaying (PSR) and time switching relaying (TSR) protocols for decode-and-forward (DF)-based relay networks consisting of a source, a relay, and a ...destination. For the networks, the relay is assumed to have a rechargeable battery with a certain amount of remaining energy for energy harvesting through the received signal transmitted from the source. Specifically, for the PSR protocol with and without the direct-path, we present the outage probability expression with a given power splitting coefficient, and we obtain the optimum power splitting coefficient to maximize the transmission rate and derive its transmission rate and outage probability, where the optimum coefficient depends on channel conditions and remaining energy. For the TSR protocol with and without the direct-path, we present the outage probability expression with a given time switching coefficient, and we obtain the optimum time switching coefficient to maximize the transmission rate and derive its transmission rate, where the optimum coefficient also depends on channel conditions and remaining energy.
The switch between stem/progenitor cell expansion and differentiation is critical for organ homeostasis. The mammalian Hippo pathway effector and oncoprotein YAP expands undifferentiated ...stem/progenitor cells in various tissues. However, the YAP-associated transcription factors and downstream targets underlying this stemness-promoting activity are poorly understood. Here we show that the SRF-IL6 axis is the critical mediator of YAP-induced stemness in mammary epithelial cells and breast cancer. Specifically, serum response factor (SRF)-mediated binding and recruitment of YAP to mammary stem cell (MaSC) signature-gene promoters induce numerous MaSC signature genes, among which the target interleukin (IL)-6 is critical for YAP-induced stemness. High SRF-YAP/TAZ expression is correlated with IL6-enriched MaSC/basal-like breast cancer (BLBC). Finally, we show that this high SRF expression enables YAP to more efficiently induce IL6 and stemness in BLBC compared with luminal-type breast cancer. Collectively, our results establish the importance of SRF-YAP-IL6 signalling in promoting MaSC-like properties in a BLBC-specific manner.
In the realm of autonomous driving, motion planning for the ego vehicle necessitates the prediction of surrounding vehicles' motions. This prediction traditionally relies on object tracking modules ...containing several sensors to gauge vehicle positions and velocities. However, existing physical or maneuver-based model approaches overlook important aspects of vehicle interactions that significantly affect actual vehicle movement. Ignoring these interactions can lead to inadequate ego vehicle's motion planning. Addressing this gap, this paper proposes a novel approach: the Collision Probability Field (CPF)-based interaction-aware longitudinal motion prediction. Our methodology uniquely integrates the CPF, derived from the uncertainty of sensing information, to account for the probabilistic state of vehicle positions and velocities. This allows the prediction algorithm to consider not just the static data, but also the dynamic interactions between vehicles such as collision. Our approach was tested in various scenarios, including lane changes with an approaching vehicle from behind and different driver behavior models in real-world conditions. Our findings demonstrate a significant improvement in prediction accuracy for the motion planning of ego vehicle, highlighting the importance of interaction-aware predictions in autonomous driving systems.
Most electrolytes for rechargeable Mg batteries require time-consuming conditioning or precycling process to achieve a fully reversible Mg deposition/dissolution, which hinders the normal operation ...of Mg batteries. This study details a simple and effective method for eliminating this conditioning behavior using heptamethyldisilazane (HpMS) as an electrolyte additive. It was found that the HpMS additive greatly increases the current density and Coulombic efficiency of Mg deposition/dissolution from the initial cycles in various sulfone and glyme solutions containing MgCl2 or Mg(TFSI)2. The beneficial effect of HpMS was ascribed to its ability to scavenge trace water in the electrolytes and remove Mg(OH)2 and Mg(TFSI)2-decomposition products from the Mg surface. Considering its applicability for a wide range of Mg electrolytes, the use of HpMS is expected to accelerate the development of practical Mg batteries.
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