Role of dark excitations in the nonequilibrium condensation of exciton polaritons in optically-pumped organic single crystal microcavities

2015 ◽  
Vol 29 (22) ◽  
pp. 1550157 ◽  
Author(s):  
Svitlana Zaster ◽  
Eric R. Bittner
Keyword(s):  
Reaction Diffusion ◽  
Optically Pumped ◽  
Reaction Diffusion Model ◽  
Exciton Polaritons ◽  
Organic Single Crystal ◽  
Dielectric Mirrors ◽  
Dynamical Regimes ◽  
Nonequilibrium Condensation ◽  
External Driving

We present a reaction/diffusion model for the formation of a lower polariton condensate in a microcavity containing an organic semiconducting molecular crystalline film. Our model–based upon an anthracene film sandwiched between two reflecting dielectric mirrors–consists of three coupled fields corresponding to a gas of excitons created by an external driving pulse, a reservoir of dark states formed by the nonemissive decay of excitons in to nearby electronic states, and a lower polariton condensate. We show that at finite temperature, the presence of the dark reservoir can augment the exciton population such that a lower critical pumping threshold is required to achieve the critical exciton densities required to sustain a stable condensate population. Using linear-stability analysis, we show that a variety of dynamical regimes can emerge depending upon the characteristics of the cavity and the lattice temperature.

scholarly journals Reaction-diffusion model as framework for understanding the role of riboflavin in “eye defence” formulations

RSC Advances ◽  
2020 ◽  
Vol 10 (25) ◽  
pp. 14965-14971
Author(s):  
Francesca Di Nezza ◽  
Ciro Caruso ◽  
Ciro Costagliola ◽  
Luigi Ambrosone
Keyword(s):  
Diffusion Model ◽  
Reaction Diffusion ◽  
Eye Drops ◽  
Reaction Diffusion Model ◽  
Visible Spectra ◽  
Uv Visible

Analysis of UV-visible spectra, performed on commercial riboflavin-based eye drops, showed that absorbance is a saturating function of vitamin concentration.

scholarly journals Nonclassical Kinetics in Constrained Geometries: Initial Distribution Effects

1998 ◽  
Vol 08 (05) ◽  
pp. 853-868 ◽  
Author(s):  
K. Lindenberg ◽  
A. H. Romero ◽  
J. M. Sancho
Keyword(s):  
Initial Density ◽  
Reaction Diffusion ◽  
Initial Distribution ◽  
Density Fluctuations ◽  
Time Behavior ◽  
Numerical Work ◽  
Irreversible Reaction ◽  
Long Wavelength ◽  
Reaction Diffusion Model

We present a detailed study of the effects of the initial distribution on the kinetic evolution of the irreversible reaction A+B→0 in one dimension. Our analytic as well as numerical work is based on a reaction–diffusion model of this reaction. We focus on the role of initial density fluctuations in the creation of the macroscopic patterns that lead to the well-known kinetic anomalies in this system. In particular, we discuss the role of the long wavelength components of the initial fluctuations in determining the long-time behavior of the system. We note that the frequently studied random initial distribution is but one of a variety of possible distributions leading to interesting anomalous behavior. Our discussion includes an initial distribution with correlated A-B pairs and one in which the initial distribution forms a fractal pattern. The former is an example of a distribution whose long wavelength components are suppressed, while the latter exemplifies one whose long wavelength components are enhanced, relative to those of the random distribution.

scholarly journals Source-sink dynamics can maintain mismatched range and bioclimatic limits even at large spatial scales

2020 ◽  
Author(s):  
Nikunj Goel ◽  
Timothy H. Keitt
Keyword(s):  
Spatial Scales ◽  
Reaction Diffusion ◽  
Dispersal Distance ◽  
Life Strategy ◽  
Stepping Stones ◽  
Reaction Diffusion Model ◽  
Primary Determinant ◽  
Source Sink ◽  
Bioclimatic Envelope

AbstractBioclimatic models assume that at broad spatial scales, climate is the primary determinant of species distribution. Meanwhile, processes such as source-sink dynamics can be ignored because they are thought to manifest at length scales comparable to species mean dispersal distance. We present a reaction-diffusion model to show species can use sink patches near the bioclimatic (or niche) limit as stepping-stones to occupy sinks much further than the mean dispersal distance, thereby extending the distribution far beyond the bioclimatic envelope. This mismatch between geographical and bioclimatic limits is mediated by the shape of the bioclimatic limit and may be significant for low growth sensitivity and fast dispersal life strategy. These findings challenge one of the core assumptions of the bioclimatic models. Therefore, we advocate that biogeographers consider the role of dispersal when using bioclimatic models to generate inferences about the ecological and evolutionary processes that determine the distribution of biota.

scholarly journals The Role of Cytoplasmic Interactions in the Collective Polarization of Tissues and its Interplay with Cellular Geometry

2018 ◽  
Author(s):  
Shahriar Shadkhoo ◽  
Madhav Mani
Keyword(s):  
Large Scale ◽  
Planar Cell Polarity ◽  
Reaction Diffusion ◽  
Directional Information ◽  
Collective Response ◽  
Reaction Diffusion Model ◽  
Necessary And Sufficient ◽  
Molecular Components ◽  
Theory And Experiments

AbstractPlanar cell polarity (PCP), the ability of a tissue to polarize coherently over multicellular length scales, provides the directional information that guides a multitude of developmental processes at cellular and tissue levels. While it is manifest that cells utilize both intra-cellular and intercellular mechanisms, how they couple together to produce the collective response remains an active area of investigation. Exploring a phenomeno-logical reaction-diffusion model, we predict a crucial, and novel, role for cytoplasmic interactions in the large-scale correlations of cell polarities. We demonstrate that finite-range (i.e. nonlocal) cytoplasmic interactions are necessary and sufficient for the robust and long-range polarization of tissues — even in the absence of global cues — and are essential to the faithful detection of weak directional signals. Strikingly, our model re-capitulates an observed influence of anisotropic tissue geometries on the orientation of polarity. In order to facilitate a conversation between theory and experiments, we compare five distinct classes of in silico mutants with experimental observations. Within this context, we propose quantitative measures that can guide the search for the participant molecular components, and the identification of their roles in the collective polarization of tissues.

scholarly journals Reaction-diffusion model for STIM-ORAI interaction: The role of ROS and mutations

2019 ◽  
Vol 470 ◽  
pp. 64-75 ◽  
Author(s):  
Barbara Schmidt ◽  
Dalia Alansary ◽  
Ivan Bogeski ◽  
Barbara A. Niemeyer ◽  
Heiko Rieger
Keyword(s):  
Diffusion Model ◽  
Reaction Diffusion ◽  
Reaction Diffusion Model

scholarly journals Model analogies between pattern formation in deforming engineering materials & morphogenesis in ageing human brains

2019 ◽  
Vol 28 (1) ◽  
pp. 95-106
Author(s):  
Apostolos C. Tsolakis ◽  
George Petsos ◽  
Olga Kapetanou ◽  
Ioannis N. Nikolaidis ◽  
Elias C. Aifantis
Keyword(s):  
Pattern Formation ◽  
Reaction Diffusion ◽  
Reaction Diffusion Model ◽  
Biochemical Systems ◽  
Model Cell ◽  
Material Physics ◽  
Engineering Materials ◽  
Human Brains ◽  
Ageing Brain

AbstractMathematical models developed within the material mechanics and material physics communities have been routinely adapted to interpret and further understand physiological and biological processes. The field of biomechanics, in particular, has emerged from a direct application of elasticity and fluid mechanics theories to model cell and tissue behavior, as well as bone fracture and blood flow. On the other hand, Turing’s reaction-diffusion model of morphogenesis for biochemical systems has been adapted to interpret pattern formation in deforming materials. An important aspect, however, that has not been sufficiently examined is to investigate the role of an externally applied or internally developed stress. Another, equally interesting issue that has not been adequately explored, concerns the development of a common effective methodology to analyze signals and images for both humanmade and naturemade systems, especially when differential equations are not available to use for this purpose. The article is an initial modest effort to discuss such common features between nonliving and living materials. It focuses, in particular, to modeling analogies between pattern formation of defects in deforming engineering materials under application of external stress and morphogenesis of cellular structures in ageing brain tissue under development of internal stress.

scholarly journals Systems modeling predicts that mitochondria ER contact sites regulate the postsynaptic energy landscape

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
A. Leung ◽  
D. Ohadi ◽  
G. Pekkurnaz ◽  
P. Rangamani
Keyword(s):  
Atp Hydrolysis ◽  
Energy State ◽  
Reaction Diffusion ◽  
Spatiotemporal Model ◽  
Atp Production ◽  
Contact Sites ◽  
Reaction Diffusion Model ◽  
Intracellular Organelles ◽  
Atp Generation

AbstractSpatiotemporal compartmentation of calcium dynamics is critical for neuronal function, particularly in postsynaptic spines. This exquisite level of Ca2+ compartmentalization is achieved through the storage and release of Ca2+ from various intracellular organelles particularly the endoplasmic reticulum (ER) and the mitochondria. Mitochondria and ER are established storage organelles controlling Ca2+ dynamics in neurons. Mitochondria also generate a majority of energy used within postsynaptic spines to support the downstream events associated with neuronal stimulus. Recently, high resolution microscopy has unveiled direct contact sites between the ER and the mitochondria (MERCs), which directly channel Ca2+ release from the ER into the mitochondrial membrane. In this study, we develop a computational 3D reaction-diffusion model to investigate the role of MERCs in regulating Ca2+ and ATP dynamics. This spatiotemporal model accounts for Ca2+ oscillations initiated by glutamate stimulus of metabotropic and ionotropic glutamate receptors and Ca2+ changes in four different compartments: cytosol, ER, mitochondria, and the MERC microdomain. Our simulations predict that the organization of these organelles and inter-organellar contact sites play a key role in modulating Ca2+ and ATP dynamics.We further show that the crosstalk between geometry (mitochondria and MERC) and metabolic parameters (cytosolic ATP hydrolysis, ATP generation) influences the neuronal energy state. Our findings shed light on the importance of organelle interactions in predicting Ca2+ dynamics in synaptic signaling. Overall, our model predicts that a combination of MERC linkage and mitochondria size is necessary for optimal ATP production in the cytosol.

Polariton – polariton scattering and the nonequilibrium condensation of exciton polaritons in semiconductor microcavities

2003 ◽  
Vol 173 (9) ◽  
pp. 995
Author(s):  
V.D. Kulakovskii ◽  
D.N. Krizhanovskii ◽  
A.I. Tartakovskii ◽  
Nikolai A. Gippius ◽  
Sergei G. Tikhodeev
Keyword(s):  
Exciton Polaritons ◽  
Semiconductor Microcavities ◽  
Nonequilibrium Condensation
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