scholarly journals Hydrogen peroxide thermochemical oscillator as driver for primordial RNA replication

2014 ◽  
Author(s):  
Rowena Ball ◽  
John Brindley
Keyword(s):  
Hydrogen Peroxide ◽  
Flow System ◽  
Molecular System ◽  
Rna Replication ◽  
System Model ◽  
Open Flow ◽  
The Mean ◽  
Prebiotic Earth ◽  
Primordial Soup ◽  
Input Amount

This paper presents and tests a previously unrecognised mechanism for driving a replicating molecular system on the prebiotic earth. It is proposed that cell-free RNA replication in the primordial soup may have been driven by self-sustained oscillatory thermochemical reactions. To test this hypothesis a well-characterised hydrogen peroxide oscillator was chosen as the driver and complementary RNA strands with known association and melting kinetics were used as the substrate. An open flow system model for the self-consistent, coupled evolution of the temperature and concentrations in a simple autocatalytic scheme is solved numerically, and it is shown that thermochemical cycling drives replication of the RNA strands. For the (justifiably realistic) values of parameters chosen for the simulated example system, the mean amount of replicant produced at steady state is 6.56 times the input amount, given a constant supply of substrate species. The spontaneous onset of sustained thermochemical oscillations via slowly drifting parameters is demonstrated, and a scheme is given for prebiotic production of complementary RNA strands on rock surfaces.

scholarly journals Hydrogen peroxide thermochemical oscillator as driver for primordial RNA replication

2014 ◽  
Vol 11 (95) ◽  
pp. 20131052 ◽  
Author(s):  
Rowena Ball ◽  
John Brindley
Keyword(s):  
Hydrogen Peroxide ◽  
Flow System ◽  
Molecular System ◽  
Rna Replication ◽  
System Model ◽  
Open Flow ◽  
The Mean ◽  
Prebiotic Earth ◽  
Primordial Soup ◽  
Input Amount

This paper presents and tests a previously unrecognized mechanism for driving a replicating molecular system on the prebiotic earth. It is proposed that cell-free RNA replication in the primordial soup may have been driven by self-sustained oscillatory thermochemical reactions. To test this hypothesis, a well-characterized hydrogen peroxide oscillator was chosen as the driver and complementary RNA strands with known association and melting kinetics were used as the substrate. An open flow system model for the self-consistent, coupled evolution of the temperature and concentrations in a simple autocatalytic scheme is solved numerically, and it is shown that thermochemical cycling drives replication of the RNA strands. For the (justifiably realistic) values of parameters chosen for the simulated example system, the mean amount of replicant produced at steady state is 6.56 times the input amount, given a constant supply of substrate species. The spontaneous onset of sustained thermochemical oscillations via slowly drifting parameters is demonstrated, and a scheme is given for prebiotic production of complementary RNA strands on rock surfaces.

Stability and Stabilization for Discrete System With Probabilistic Nonlinearities

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Xia Zhao ◽  
Engang Tian
Keyword(s):  
Sufficient Conditions ◽  
Discrete Systems ◽  
System Model ◽  
Linear Matrix ◽  
Time Varying Delay ◽  
Mean Square Stability ◽  
New Type ◽  
Stability And Stabilization ◽  
The Mean ◽  
Varying Delay

This paper investigates stability and stabilization of discrete systems with probabilistic nonlinearities and time-varying delay. New characters of the nonlinearities, the probability of the nonlinearities happening between different bounds, are used to build new type of system model, which can help us make a full use of the inner variation information of the nonlinearities. With the help of the new characters, new system model is proposed. Then, sufficient conditions for the mean square stability of the system can be obtained by using the Lyapunov functional approach and linear matrix inequalities technique. An example is proposed to illustrate the efficiency of the proposed method.

Bursting phenomena in a simplified Oregonator flow system model

1982 ◽  
Vol 76 (4) ◽  
pp. 1775-1789 ◽  
Author(s):  
John Rinzel ◽  
William C. Troy
Keyword(s):  
Flow System ◽  
System Model ◽  
Bursting Phenomena

On the Mechanism of Spatial Bifurcations in the Open Flow System

1997 ◽  
Vol 07 (07) ◽  
pp. 1529-1538 ◽  
Author(s):  
Akihiro Yamaguchi
Keyword(s):  
Flow System ◽  
Coupled Map Lattice ◽  
Open Flow ◽  
Analytical Results

The phenomenon of spatial bifurcations in the open flow system (OFS), which is a unidirectionally coupled map lattice, is investigated. The bifurcation conditions are obtained by analyzing the effect of deterministic discretization of the system's state when the OFS is simulated by the computer. The analytical results are examined by application to the OFS with logistic maps.

Design and implementation of automatic control for a condensation-induced depressurization system

2018 ◽  
Vol 233 (9) ◽  
pp. 1146-1158
Author(s):  
Fen Du ◽  
Bo Zhang ◽  
Chao Zhu ◽  
Zhiming Ji ◽  
Chao-Hsin Lin
Keyword(s):  
Control System ◽  
Atmospheric Pressure ◽  
Flow System ◽  
Thermodynamic Cycle ◽  
Saturated Steam ◽  
Low Grade ◽  
Steam Condensation ◽  
Open Flow ◽  
Process Characteristics ◽  
Cascade Arrangement

This study develops a control system to automate the operation of a condensation-induced depressurization technology, which is used to achieve sub-atmospheric pressure in an open-flow system on ground. The continuous depressurization is maintained via an integrated series of chambers inside which vacuum is regenerated by condensing and refilling of saturated steam. The low pressure generated inside the chambers is then used to alternatively extract the air out of a flow system for maintaining its sub-atmospheric pressure. The thermodynamic cycle in such a vacuum chamber consists of three sub-processes: air purging to ambient by steam refilling, depressurization by steam condensation, and air-extraction from a flow application. As one chamber undergoing these consecutive processes, another chamber operates in a coordinated different phase to seamlessly maintain a continuous air-extraction operation. This new system provides a quiet and efficient way of using low-grade energy to generate hypobaric environment for needed applications. A cascade arrangement of a proposed multiple-chamber operation is also illustrated. A control system is designed and implemented to realize the automatic and coordinated operation in a dual-chamber, laboratory-scaled system. Exemplified results on process characteristics such as chamber depressurization and air purging are also provided.

scholarly journals Barley seed sensitivity to water stress at germination stage

2011 ◽  
Vol 48 (No. 7) ◽  
pp. 293-297
Author(s):  
V. Hosnedl ◽  
H. Honsová
Keyword(s):  
Hydrogen Peroxide ◽  
Extreme Values ◽  
Oxygen Deficiency ◽  
Barley Seed ◽  
Seed Vigour ◽  
Water Sensitivity ◽  
The Mean ◽  
Laboratory Emergence ◽  
Mean Time ◽  
Higher Sensitivity

Barley seed sensitivity to water and anoxia was tested. Standard germination, mean time of germination (MTG), germination in sand wetted by water to 100% water capacity (anoxia) or by hydrogen peroxide (wet conditions without anoxia), germination in 0.75% hydrogen peroxide and laboratory emergence (15 and 20&deg;C) were evaluated. Barley seed responds sensitively to stress conditions during germination. Significant germination decrease was found in abundance of water. Percentage of reduction depends on the variety and on the year of seed production. Extreme values of water sensitivity are in interval 4&ndash;90%. At wetted sand by 0.75%, solution of H<sub>2</sub>O<sub>2</sub> the germination was significantly less reduced. That means that barley seed is very sensitive to oxygen deficiency above all and is less injured by quick imbibition. Heterogeneity in seed vigour was demonstrated in laboratory emergence tests. Quick test of germination in 0.75% hydrogen peroxide deserves attention for its high correlation coefficient with the seed laboratory emergence. The results significantly demonstrate a&nbsp;higher sensitivity of deteriorated seed to germination in abiotic stresses conditions. Variability in speed of germination is increasing, which unfavourably extends the mean time of germination.

scholarly journals Stochastic Memristive Quaternion-Valued Neural Networks with Time Delays: An Analysis on Mean Square Exponential Input-to-State Stability

Mathematics ◽  
2020 ◽  
Vol 8 (5) ◽  
pp. 815 ◽  
Author(s):  
Usa Humphries ◽  
Grienggrai Rajchakit ◽  
Pramet Kaewmesri ◽  
Pharunyou Chanthorn ◽  
Ramalingam Sriraman ◽  
...  
Keyword(s):  
Neural Networks ◽  
Continuous Time ◽  
Lyapunov Functional ◽  
Time Delays ◽  
System Model ◽  
Mean Square ◽  
New Class ◽  
Quaternion Multiplication ◽  
The Mean ◽  
Theoretical Results

In this paper, we study the mean-square exponential input-to-state stability (exp-ISS) problem for a new class of neural network (NN) models, i.e., continuous-time stochastic memristive quaternion-valued neural networks (SMQVNNs) with time delays. Firstly, in order to overcome the difficulties posed by non-commutative quaternion multiplication, we decompose the original SMQVNNs into four real-valued models. Secondly, by constructing suitable Lyapunov functional and applying It o ^ ’s formula, Dynkin’s formula as well as inequity techniques, we prove that the considered system model is mean-square exp-ISS. In comparison with the conventional research on stability, we derive a new mean-square exp-ISS criterion for SMQVNNs. The results obtained in this paper are the general case of previously known results in complex and real fields. Finally, a numerical example has been provided to show the effectiveness of the obtained theoretical results.

scholarly journals A comprehensive assessment of tropical stratospheric upwelling in the specified dynamics Community Earth System Model 1.2.2 – Whole Atmosphere Community Climate Model (CESM (WACCM))

2020 ◽  
Vol 13 (2) ◽  
pp. 717-734 ◽  
Author(s):  
Nicholas A. Davis ◽  
Sean M. Davis ◽  
Robert W. Portmann ◽  
Eric Ray ◽  
Karen H. Rosenlof ◽  
...  
Keyword(s):  
Climate Models ◽  
Climate Model ◽  
Earth System Model ◽  
System Model ◽  
Trace Gas ◽  
Earth System ◽  
Mean Meridional Circulation ◽  
Community Earth System Model ◽  
The Mean ◽  
Wave Momentum

Abstract. Specified dynamics (SD) schemes relax the circulation in climate models toward a reference meteorology to simulate historical variability. These simulations are widely used to isolate the dynamical contributions to variability and trends in trace gas species. However, it is not clear if trends in the stratospheric overturning circulation are properly reproduced by SD schemes. This study assesses numerous SD schemes and modeling choices in the Community Earth System Model (CESM) Whole Atmosphere Chemistry Climate Model (WACCM) to determine a set of best practices for reproducing interannual variability and trends in tropical stratospheric upwelling estimated by reanalyses. Nudging toward the reanalysis meteorology as is typically done in SD simulations does not accurately reproduce lower-stratospheric upwelling trends present in the underlying reanalysis. In contrast, nudging to anomalies from the climatological winds or anomalies from the zonal-mean winds and temperatures better reproduces trends in lower-stratospheric upwelling, possibly because these schemes do not disrupt WACCM's climatology. None of the schemes substantially alter the structure of upwelling trends – instead, they make the trends more or less AMIP-like. An SD scheme's performance in simulating the acceleration of the shallow branch of the mean meridional circulation from 1980 to 2017 hinges on its ability to simulate the downward shift of subtropical lower-stratospheric wave momentum forcing. Key to this is not nudging the zonal-mean temperature field. Gravity wave momentum forcing, which drives a substantial fraction of the upwelling in WACCM, cannot be constrained by nudging and presents an upper limit on the performance of these schemes.

scholarly journals Development of a Simple Reversible-Flow Method for Preparation of Micron-Size Chitosan-Cu(II) Catalyst Particles and Their Testing of Activity

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1798 ◽  
Author(s):  
Apichai Intanin ◽  
Prawpan Inpota ◽  
Threeraphat Chutimasakul ◽  
Jonggol Tantirungrotechai ◽  
Prapin Wilairat ◽  
...  
Keyword(s):  
Alkaline Solution ◽  
Catalytic Reduction ◽  
Flow System ◽  
Flow Line ◽  
Switching Valve ◽  
Micron Size ◽  
Droplet Production ◽  
The Mean ◽  
Simple Flow ◽  
Representative Samples

A simple flow system employing a reversible-flow syringe pump was employed to synthesize uniform micron-size particles of chitosan-Cu(II) (CS-Cu(II)) catalyst. A solution of chitosan and Cu(II) salt was drawn into a holding coil via a 3-way switching valve and then slowly pumped to drip into an alkaline solution to form of hydrogel droplets. The droplets were washed and dried to obtain the catalyst particles. Manual addition into the alkaline solution or employment of flow system with a vibrating rod, through which the end of the flow line is inserted, was investigated for comparison. A sampling method was selected to obtain representative samples of the population of the synthesized particles for size measurement using optical microscopy. The mean sizes of the particles were 880 ± 70 µm, 780 ± 20 µm, and 180 ± 30 µm for the manual and flow methods, without and with the vibrating rod, respectively. Performance of the flow methods, in terms of rate of droplet production and particle size distribution, are discussed. Samples of 180 µm size CS-Cu(II) particles were tested for catalytic reduction of 0.5 mM p-nitrophenol to p-aminophenol by 100-fold excess borohydride. The conversion was 98% after 20 min, whereas without the catalyst there was only 14% conversion.

scholarly journals Development and evaluation of a tropical feed library for the Cornell Net Carbohydrate and Rrotein System model

2002 ◽  
Vol 59 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Luís Orlindo Tedeschi ◽  
Danny Gene Fox ◽  
Alice N. Pell ◽  
Dante Pazzanese Duarte Lanna ◽  
Celso Boin
Keyword(s):  
Chemical Composition ◽  
System Model ◽  
Insufficient Data ◽  
Scientific Journals ◽  
Specific Production ◽  
Information Need ◽  
Feed Composition ◽  
Tropical Regions ◽  
The Mean

The Cornell Net Carbohydrate and Protein System (CNCPS) model has been increasingly used in tropical regions for dairy and beef production. However, the lack of appropriate characterization of the feeds has restricted its application. The objective of this study was to develop and evaluate a feed library containing feeds commonly used in tropical regions with characteristics needed as inputs for the CNCPS. Feed composition data collected from laboratory databases and from experiments published in scientific journals were used to develop this tropical feed library. The total digestible nutrients (TDN) predicted at 1x intake of maintenance requirement with the CNCPS model agreed with those predicted by the Weiss et al. (1992) equation (r² of 92.7%, MSE of 13, and bias of 0.8%) over all feeds. However, the regression r² of the tabular TDN values and the TDN predicted by the CNCPS model or with the Weiss equation were much lower (58.1 and 67.5%, respectively). A thorough comparison between observed and predicted TDN was not possible because of insufficient data to characterize the feeds as required by our models. When we used the mean chemical composition values from the literature data, the TDN predicted by our models did not agree with the measured values. We conclude using the TDN values calculated using the Weiss equation and the CNCPS model that are based on the actual chemical composition of the feeds result in energy values that more accurately represent the feeds being used in specific production situations than do the tabular values. Few papers published in Latin America journals that were used in this study reported information need by models such as the CNCPS.

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