scholarly journals Green notes: The rhythms of cyanobacteria exoelectrogenesis as de-composed by the Hilbert-Huang transform

2021 ◽  
Author(s):  
Tonny Ipael Okedi ◽  
Kamran Yunus ◽  
Adrian Fisher
Keyword(s):  
Photosystem Ii ◽  
Current Density ◽  
Applied Research ◽  
State Of The Art ◽  
Circadian Period ◽  
Density Profiles ◽  
Glycogen Accumulation ◽  
Hilbert Huang Transform ◽  
Circadian Phase ◽  
Instantaneous Frequencies

Electrons from cyanobacteria photosynthetic and respiratory systems are implicated in current generated in biophotovoltaic (BPV) devices. However, the pathway that electrons follow to electrodes remains largely unknown, limiting progress of applied research. Here we use Hilbert-Huang transforms to decompose Synechococcus elongatus sp. PCC7942 BPV current density profiles into physically meaningful oscillatory components, and compute their instantaneous frequencies. We develop hypotheses for the genesis of the oscillations via repeat experiments with iron-depleted and 20% CO2 enriched biofilms. The oscillations exhibit rhythms that are consistent with the state of the art cyanobacteria circadian model, and putative exoelectrogenic pathways. In particular, we observe oscillations consistent with: rhythmic D1:1 (photosystem II core) expression; circadian-controlled glycogen accumulation; circadian phase shifts under modified intracellular %ATP; and circadian period shortening in the absence of the iron-sulphur protein LdpA. We suggest that the extracted oscillations may be used to reverse-identify proteins and/or metabolites responsible for cyanobacteria exoelectrogenesis.

Current Density Profiles of Surface Mounted and Recessed Electrodes for Neural Prostheses

1987 ◽  
Vol BME-34 (11) ◽  
pp. 864-875 ◽  
Author(s):  
Jay T. Rubinstein ◽  
Francis A. Spelman ◽  
Mani Soma ◽  
Michael F. Suesserman
Keyword(s):  
Current Density ◽  
Neural Prostheses ◽  
Density Profiles

scholarly journals 0433 Targeting Light Sensitivity Parameters to Optimize Circadian Phase Predictions

SLEEP ◽  
2020 ◽  
Vol 43 (Supplement_1) ◽  
pp. A166-A166
Author(s):  
J E Stone ◽  
E M McGlashan ◽  
S W Cain ◽  
A J Phillips
Keyword(s):  
Sensitivity Analysis ◽  
Circadian Clock ◽  
Mean Absolute Error ◽  
Light Response ◽  
Absolute Error ◽  
Light Sensitivity ◽  
Model Parameters ◽  
Circadian Period ◽  
Individual Level ◽  
Circadian Phase

Abstract Introduction Existing models of the human circadian clock accurately predict phase at group-level but not at individual-level. Interindividual variability in light sensitivity is not currently accounted for in these models and may be a practical approach to improving individual-level predictions. Using the gold-standard predictive model, we (i) identified whether varying light sensitivity parameters produces meaningful changes in predicted phase in field conditions; and (ii) tested whether optimizing parameters can significantly improve accuracy of circadian phase prediction. Methods Healthy participants (n=12, 7 women, aged 18-26) underwent continuous light and activity monitoring for 3 weeks (Actiwatch Spectrum). Salivary dim light melatonin onset (DLMO) was measured each week. A model of the human circadian clock and its response to light was used to predict the three weekly DLMO times using the individual’s light data. A sensitivity analysis was performed varying three model parameters within physiological ranges: (i) amplitude of the light response [p]; (ii) advance vs. delay bias of the light response [K]; and (iii) intrinsic circadian period [tau]. These parameters were then fitted using least squares estimation to obtain optimal predictions of DLMO for each individual. Accuracy was compared between optimized parameters and default parameters. Results The default model predicted DLMO with mean absolute error of 1.02h. Sensitivity analysis showed the average range of variation in predicted DLMOs across participants was 0.65h for p, 4.28h for K and 3.26h for tau. Fitting parameters independently, we found mean absolute error of 0.85h for p, 0.71h for K and 0.75h for tau. Fitting p and K together reduced mean absolute error to 0.57h. Conclusion Light sensitivity parameters capture similar or greater variability in phase as intrinsic circadian period, indicating they are a viable option for individualising circadian phase predictions. Future prospective work is needed using measures of light sensitivity to validate this approach. Support N/A

scholarly journals Circadian phase, circadian period and chronotype are reproducible over months

2017 ◽  
Vol 35 (2) ◽  
pp. 280-288 ◽  
Author(s):  
Thomas Kantermann ◽  
Charmane I Eastman
Keyword(s):  
Circadian Period ◽  
Circadian Phase

Electrostatic and Electrodynamic Field Analyses of 33kV Line Insulators

2006 ◽  
Vol 7 (3) ◽  
Author(s):  
Ibrahim A. Metwally ◽  
Md Abdus Salam ◽  
Ali Al-Maqrashi ◽  
Saif AR Sumry ◽  
Saif SH Al-Harthy
Keyword(s):  
Electric Field ◽  
Current Density ◽  
High Current Density ◽  
Experimental Tests ◽  
Finite Element Models ◽  
High Current ◽  
Density Profiles ◽  
Fully Integrated ◽  
Software Modules ◽  
Simulation Results

Electrostatic and electrodynamic field analyses of 33kV line insulators were introduced to compare the electric-field and the current density profiles of commonly used line insulators in Oman; namely, silicone rubber (SiR) and porcelain line post insulators, and porcelain cap and pin insulator string. SLIM software package was used for such simulation, which is a fully integrated collection of software modules that provides facilities for the generation and solution of electromagnetic finite element models. The simulation results reveal that for the electrostatic simulation under pollution conditions, SiR and porcelain line-post insulators give maximum values of the electric field of 360kV/m and 1700kV/m, respectively. The latter value exceeds the recommended electric field level of 500kV/m. For the electrodynamic simulation under pollution conditions, the electric field and the current density are much higher for porcelain insulator compared to those of SiR insulator. The simulation of four cap-pin standard insulator string reveals that there is high electric field (1250kV/m) at the cap-insulator gap which can cause high current density for polluted case. Finally, the trend of the simulation results has been verified by experimental tests, which has been conducted on different 33kV line insulators having different designs and materials.

scholarly journals On Resistance and Inductance of Solid Conductors

2013 ◽  
Vol 2013 ◽  
pp. 1-14 ◽  
Author(s):  
Oldřich Coufal
Keyword(s):  
Theoretical Analysis ◽  
Current Density ◽  
State Of The Art ◽  
Electrical Engineering ◽  
The State ◽  
Electrical Circuits ◽  
Respective Field ◽  
Solid Conductors ◽  
Real Solid

The concepts of resistance and inductance are strewn with misunderstanding and errors that result from inaccurate terminology, mistakes in their definitions, and from the fact that they are quantities that characterize elements of ideal electrical circuits as well as real solid conductors. This is shown unfavourably not only in the respective field of the theory of electrical engineering, but also in the calculation of resistance and inductance. In this paper, a brief theoretical analysis of the state of the art is given, and its results are applied in the calculation of the current density, resistance, and inductance of two coaxial solid tubular conductors.

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