scholarly journals Modeling Of the Phytoplankton Dynamics Considering the Mechanisms of Ectocrine Regulation

2015 ◽  
Vol 10 (1) ◽  
pp. 178-192 ◽  
Author(s):  
О.Л. Жданова ◽  
O.L. Zhdanova
Keyword(s):  
Growth Rate ◽  
Nutrient Availability ◽  
Growth Regulation ◽  
Space Time ◽  
Phytoplankton Growth ◽  
Nonlinear Dependence ◽  
Phytoplankton Dynamics ◽  
Time Model ◽  
Phytoplankton Growth Rate ◽  
Space Time Model

In the paper set of models that take into account various mechanisms for ectokrine regulation of phytoplankton growth are proposed and studied. The considered models are following: with a nonlinear dependence of phytoplankton growth rate on the concentration of the metabolite in the environment; with a metabolite, which increases both the growth rate and mortality of the phytoplankton; with two different metabolites, one of which increases the rate of growth of phytoplankton, and the second - is reduced. These models are modifications of the classical space-time model of the dynamics of phytoplankton, linking change in its density and the concentration of nutrients in space and time, which do not consider the mechanism of ectokrine growth regulation. By the means of the model it has been shown, that the metabolites secreted by algae are able to stabilize the growth of phytoplankton in conditions of excessive nutrient availability.

A modeling approach to simulate impact of climate change in lake water quality: phytoplankton growth rate assessment

1998 ◽  
Vol 37 (2) ◽  
pp. 177-185 ◽  
Author(s):  
Hany Hassan ◽  
Keisuke Hanaki ◽  
Tomonori Matsuo
Keyword(s):  
Climate Change ◽  
Water Quality ◽  
Growth Rate ◽  
Dissolved Oxygen ◽  
Lake Water ◽  
Phytoplankton Growth ◽  
Quality Data ◽  
Model Parameters ◽  
Lake Water Quality ◽  
Phytoplankton Growth Rate

Global climate change induced by increased concentrations of greenhouse gases (especially CO2) is expected to include changes in precipitation, wind speed, incoming solar radiation, and air temperature. These major climate variables directly influence water quality in lakes by altering changes in flow and water temperature balance. High concentration of nutrient enrichment and expected variability of climate can lead to periodic phytoplankton blooms and an alteration of the neutral trophic balance. As a result, dissolved oxygen levels, with low concentrations, can fluctuate widely and algal productivity may reach critical levels. In this work, we will present: 1) recent results of GCMs climate scenarios downscaling project that was held at the University of Derby, UK.; 2) current/future comparative results of a new mathematical lake eutrophication model (LEM) in which output of phytoplankton growth rate and dissolved oxygen will be presented for Suwa lake in Japan as a case study. The model parameters were calibrated for the period of 1973–1983 and validated for the period of 1983–1993. Meterologic, hydrologic, and lake water quality data of 1990 were selected for the assessment analysis. Statistical relationships between seven daily meteorological time series and three airflow indices were used as a means for downscaling daily outputs of Hadley Centre Climate Model (HadCM2SUL) to the station sub-grid scale.

Tail asymptotics of an infinitely divisible space-time model with convolution equivalent Lévy measure

2021 ◽  
Vol 58 (1) ◽  
pp. 42-67 ◽  
Author(s):  
Mads Stehr ◽  
Anders Rønn-Nielsen
Keyword(s):  
Space Time ◽  
Time Interval ◽  
Lévy Measure ◽  
Infinitely Divisible ◽  
Time Model ◽  
Spatial Object ◽  
Tail Behaviour ◽  
Fixed Radius ◽  
The Right ◽  
Space Time Model

AbstractWe consider a space-time random field on ${{\mathbb{R}^d} \times {\mathbb{R}}}$ given as an integral of a kernel function with respect to a Lévy basis with a convolution equivalent Lévy measure. The field obeys causality in time and is thereby not continuous along the time axis. For a large class of such random fields we study the tail behaviour of certain functionals of the field. It turns out that the tail is asymptotically equivalent to the right tail of the underlying Lévy measure. Particular examples are the asymptotic probability that there is a time point and a rotation of a spatial object with fixed radius, in which the field exceeds the level x, and that there is a time interval and a rotation of a spatial object with fixed radius, in which the average of the field exceeds the level x.

A Deterministic Sea-Clutter Space–Time Model Based on Physical Sea Surface

2016 ◽  
Vol 54 (11) ◽  
pp. 6659-6673 ◽  
Author(s):  
Zhihui Xin ◽  
Guisheng Liao ◽  
Zhiwei Yang ◽  
Yuhong Zhang ◽  
Hongxing Dang
Keyword(s):  
Space Time ◽  
Sea Surface ◽  
Sea Clutter ◽  
Time Model ◽  
Model Based ◽  
Space Time Model

Beyond Gödel’s Time

2018 ◽  
Vol 4 (1) ◽  
Author(s):  
Peter Riggs
Keyword(s):  
Theoretical Model ◽  
Space Time ◽  
Time Model ◽  
Space Time Model

The Gödel space-time model displays an intrinsic rotation of matter, which is responsible for some fascinating characteristics. It is a theoretical model of a possible, though not the actual, universe.

Theory of the Stationary Self-Consistent Universe

2021 ◽  
Author(s):  
Alexander Shamailovich Avshalumov
Keyword(s):  
Quantum Physics ◽  
Space Time ◽  
Theoretical Physics ◽  
Time Model ◽  
Zero Curvature ◽  
Modern Cosmology ◽  
Simultaneous Existence ◽  
Three Space ◽  
Space Time Model ◽  
The Universe

Since the creation of GR and subsequent works in cosmology, the question of the curvature of space in the Universe is considered one of the most important and debated to this day. This is evident, because the curvature of space depends whether the Universe expands, contracts or is static. These discussions allowed the author to propose a paradoxical idea: simultaneous existence in the Universe of three interconnected space-times (positive, negative and zero curvature) and on this basis, to develop a theory in which each space-time plays its own role and develops in a strict accordance with its sign of curvature. The three space-time model of the structure of the Universe, proposed by the author, allows to solve many fundamental problems of modern cosmology and theoretical physics and creates the basis for building a unified physical theory (including one that unites GR and quantum physics).

scholarly journals A Space-Time Model with Application to Annual Temperature Anomalies;

2003 ◽  
Vol 10 (1) ◽  
pp. 19-30
Author(s):  
Eui-Kyoo Lee ◽  
Myung-Sang Moon ◽  
Richard F. Gunst
Keyword(s):  
Space Time ◽  
Time Model ◽  
Temperature Anomalies ◽  
Space Time Model

INFLATIONARY SCENARIO IN BRANS–DICKE THEORY FOR BIANCHI VI0 SPACE–TIME MODEL

2003 ◽  
Vol 12 (01) ◽  
pp. 129-143 ◽  
Author(s):  
SUBENOY CHAKRABORTY ◽  
ARABINDA GHOSH
Keyword(s):  
Equation Of State ◽  
Perfect Fluid ◽  
Analytical Solutions ◽  
Fluid Model ◽  
Space Time ◽  
Time Model ◽  
Exact Analytical Solutions ◽  
Exponential Expansion ◽  
Barotropic Equation ◽  
Space Time Model

We have investigated perfect fluid model in Brans–Dicke theory for Bianchi VI 0 space–time and have obtained exact analytical solutions considering barotropic equation of state. These solutions have been analyzed for different values of the parameters involved and some of them have shown a period of exponential expansion.

scholarly journals A joint Bayesian space–time model to integrate spatially misaligned air pollution data in R‐INLA

2020 ◽  
Vol 31 (8) ◽  
Author(s):  
C. Forlani ◽  
S. Bhatt ◽  
M. Cameletti ◽  
E. Krainski ◽  
M. Blangiardo
Keyword(s):  
Air Pollution ◽  
Space Time ◽  
Time Model ◽  
Space Time Model
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