scholarly journals Modelling Circadian Rhythms in Drosophila and Investigation of VRI and PDP1 Feedback Loops Using a New Mathematical Model

2008 ◽  
Vol 3 (2) ◽  
pp. 1-26 ◽  
Author(s):  
D. Kulasiri ◽  
Z. Xie
Keyword(s):  
Mathematical Model ◽  
Circadian Rhythms ◽  
Feedback Loops

scholarly journals Neuron-specific knockouts indicate the importance of network communication to Drosophila rhythmicity

2019 ◽  
Author(s):  
M Schlichting ◽  
MM Diaz ◽  
J Xin ◽  
M Rosbash
Keyword(s):  
Gene Expression ◽  
Circadian Rhythms ◽  
Intercellular Communication ◽  
Clock Gene ◽  
Feedback Loops ◽  
Neuronal Firing ◽  
Network Communication ◽  
Constant Darkness ◽  
Circadian Period ◽  
Clock Gene Expression

AbstractAnimal circadian rhythms persist in constant darkness and are driven by intracellular transcription-translation feedback loops. Although these cellular oscillators communicate, isolated mammalian cellular clocks continue to tick away in darkness without intercellular communication. To investigate these issues in Drosophila, we assayed behavior as well as molecular rhythms within individual brain clock neurons while blocking communication within the ca. 150 neuron clock network. We also generated CRISPR-mediated neuron-specific circadian clock knockouts. The results point to two key clock neuron groups: loss of the clock within both regions but neither one alone has a strong behavioral phenotype in darkness; communication between these regions also contributes to circadian period determination. Under these dark conditions, the clock within one region persists without network communication. The clock within the famous PDF-expressing s-LNv neurons however was strongly dependent on network communication, likely because clock gene expression within these vulnerable sLNvs depends on neuronal firing or light.

A study of the singularities in a mathematical model for circadian rhythms

Biosystems ◽  
1994 ◽  
Vol 33 (3) ◽  
pp. 193-201 ◽  
Author(s):  
Marit Pedersen ◽  
Anders Johnsson
Keyword(s):  
Mathematical Model ◽  
Circadian Rhythms

The sigmoidally transformed cosine curve: a mathematical model for circadian rhythms with symmetric non-sinusoidal shapes

2006 ◽  
Vol 25 (22) ◽  
pp. 3893-3904 ◽  
Author(s):  
Matthew R. Marler ◽  
Philip Gehrman ◽  
Jennifer L. Martin ◽  
Sonia Ancoli-Israel
Keyword(s):  
Mathematical Model ◽  
Circadian Rhythms ◽  
Cosine Curve

Coupling between phosphate and calcium homeostasis: a mathematical model

2017 ◽  
Vol 313 (6) ◽  
pp. F1181-F1199 ◽  
Author(s):  
David Granjon ◽  
Olivier Bonny ◽  
Aurélie Edwards
Keyword(s):  
Mathematical Model ◽  
Vitamin D ◽  
Parathyroid Hormone ◽  
Production Rate ◽  
Fibroblast Growth Factor 23 ◽  
Feedback Loops ◽  
Fibroblast Growth ◽  
Small Perturbations ◽  
Intracellular Pool ◽  
Negative Feedback Loops

We developed a mathematical model of calcium (Ca) and phosphate (PO4) homeostasis in the rat to elucidate the hormonal mechanisms that underlie the regulation of Ca and PO4balance. The model represents the exchanges of Ca and PO4between the intestine, plasma, kidneys, bone, and the intracellular compartment, and the formation of Ca-PO4-fetuin-A complexes. It accounts for the regulation of these fluxes by parathyroid hormone (PTH), vitamin D3, fibroblast growth factor 23, and Ca2+-sensing receptors. Our results suggest that the Ca and PO4homeostatic systems are robust enough to handle small perturbations in the production rate of either PTH or vitamin D3. The model predicts that large perturbations in PTH or vitamin D3synthesis have a greater impact on the plasma concentration of Ca2+([Ca2+]p) than on that of PO4([PO4]p); due to negative feedback loops, [PO4]pdoes not consistently increase when the production rate of PTH or vitamin D3is decreased. Our results also suggest that, following a large PO4infusion, the rapidly exchangeable pool in bone acts as a fast, transient storage PO4compartment (on the order of minutes), whereas the intracellular pool is able to store greater amounts of PO4over several hours. Moreover, a large PO4infusion rapidly lowers [Ca2+]powing to the formation of CaPO4complexes. A large Ca infusion, however, has a small impact on [PO4]p, since a significant fraction of Ca binds to albumin. This mathematical model is the first to include all major regulatory factors of Ca and PO4homeostasis.

scholarly journals Design and Testing of a Sensor Data Processing Unit for Dual-Control Missile Demonstrator

2019 ◽  
Vol 10 (2) ◽  
pp. 131-142
Author(s):  
Witold BUŻANTOWICZ ◽  
Jan PIETRASIEŃSKI
Keyword(s):  
Mathematical Model ◽  
Data Processing ◽  
Angular Rate ◽  
Feedback Loops ◽  
Sensor Data ◽  
Processing Unit ◽  
Dual Control ◽  
Electronic Components ◽  
Data Processing Unit ◽  
Design And Testing

The article discusses aspects of the design and testing of a sensor data processing unit whose function relates to the static and dynamic stabilization of a missile airframe. The authors present a mathematical model of dual-control missile dynamics, along with the autopilot implemented on the basis of two feedback loops – from acceleration and from angular rate of the airframe. The draft of the sensor data processing unit is presented in the form of three PCB packages, with connections for the installation of electronic components. In addition, a laboratory stand used in the experimental research, as well as selected results for the device are described.

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