scholarly journals Chiral polymerization and the RNA world

2005 ◽  
Vol 4 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Jonathan A.D. Wattis ◽  
Peter V. Coveney
Keyword(s):  
Mathematical Models ◽  
Rna World ◽  
Steady States ◽  
Information Storage ◽  
The Other ◽  
Symmetric System ◽  
Chemical Mechanisms ◽  
Similarities And Differences ◽  
The Stability ◽  
Parameter Values

The purpose of this paper is to review two mathematical models: one for the formation of homochiral polymers from an originally chirally symmetric system; and the other, to show how, in an RNA-world scenario, RNA can simultaneously act both as information storage and a catalyst for its own production. We note the similarities and differences in chemical mechanisms present in the systems. We review these two systems, analysing steady states, interesting kinetics and the stability of symmetric solutions. In both systems we show that there are ranges of parameter values where some chains increase their own concentrations faster than others.

scholarly journals MODELLING THE INTRODUCTION OF WOLBACHIA INTO AEDES AEGYPTI MOSQUITOES TO REDUCE DENGUE TRANSMISSION

2012 ◽  
Vol 53 (3) ◽  
pp. 213-227 ◽  
Author(s):  
MEKSIANIS Z. NDII ◽  
ROSLYN I. HICKSON ◽  
GEOFFRY N. MERCER
Keyword(s):  
Aedes Aegypti ◽  
Field Trials ◽  
Reproductive Rate ◽  
Steady States ◽  
Dengue Transmission ◽  
New Strategy ◽  
Maturation Rate ◽  
In The Wild ◽  
The Stability ◽  
Parameter Values

AbstractInfecting Aedes aegypti mosquitoes with the bacteria Wolbachia has been proposed as an innovative new strategy to reduce the transmission of dengue fever. Field trials are currently being undertaken in Queensland, Australia. However, few mathematical models have been developed to consider the persistence of Wolbachia-infected mosquitoes in the wild. This paper develops a mathematical model to determine the persistence of Wolbachia-infected mosquitoes by considering the competition between Wolbachia-infected and non-Wolbachia mosquitoes. The model has four steady states that are biologically feasible: all mosquitoes dying out, only non-Wolbachia mosquitoes surviving, and two steady states where non-Wolbachia and Wolbachia-infected mosquitoes coexist. The stability of the steady states is determined with respect to the key parameters in the mosquito life cycle. A global sensitivity analysis of the model is also conducted. The results show that the persistence of Wolbachia-infected mosquitoes is dominated by the reproductive rate, death rate, maturation rate and maternal transmission. For the parameter values where Wolbachia persists, it dominates the population, and hence the introduction of Wolbachia has great potential to reduce dengue transmission.

BEHAVIORAL DYNAMICS OF TWO INTERACTING HAWK–DOVE POPULATIONS

2001 ◽  
Vol 11 (04) ◽  
pp. 645-661 ◽  
Author(s):  
PIERRE AUGER ◽  
RAFAEL BRAVO DE LA PARRA ◽  
EVA SÁNCHEZ
Keyword(s):  
General Model ◽  
The Other ◽  
Phase Portraits ◽  
Behavioral Dynamics ◽  
Interacting Populations ◽  
Different Populations ◽  
The Stability ◽  
Individual Strategies ◽  
Parameter Values ◽  
Two Populations

We present a model of two interacting populations using two individual strategies, hawk and dove. Individuals encounter each other frequently and can change tactics several times in their life. Conflicts occur between individuals belonging to the same population and to different populations. The general model is based on the replicator equations which are used to describe the variations of the hawk proportions of the two populations. According to parameter values, namely the gain-, the intra- and inter-population costs, and the relative intra-population encounter rates, we classify the different phase portraits. We show that a decrease in the intra-population cost of a population provokes an increase in the hawk proportion in this population and of the dove proportion in the other population. An increase in the inter-population cost favors hawk strategy in the population which causes more injuries and dove strategy in the other. We also study the effects of the relative densities of the two populations on the stability of equilibria. In most cases, an increase in the relative density of a population leads to a decrease in hawk proportion in this population and of dove proportion in the other.

Uniformity of Magnification from Different Electron Microscopes

1967 ◽  
Vol 25 ◽  
pp. 32-33
Author(s):  
Godfrey C. Hoskins ◽  
V. Williams ◽  
V. Allison
Keyword(s):  
Diffraction Grating ◽  
The Other ◽  
Carbon Replica ◽  
Electron Microscopes ◽  
The Stability

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.

Orosensory Perception, Speech Production, and Deafness

1973 ◽  
Vol 16 (2) ◽  
pp. 257-266 ◽  
Author(s):  
Milo E. Bishop ◽  
Robert L. Ringel ◽  
Arthur S. House
Keyword(s):  
High School ◽  
Speech Production ◽  
Poor Performance ◽  
Normal Hearing ◽  
The Other ◽  
Functional Disorders ◽  
Form Discrimination ◽  
School Subjects ◽  
Oral Form ◽  
Similarities And Differences

The oral form-discrimination abilities of 18 orally educated and oriented deaf high school subjects were determined and compared to those of manually educated and oriented deaf subjects and normal-hearing subjects. The similarities and differences among the responses of the three groups were discussed and then compared to responses elicited from subjects with functional disorders of articulation. In general, the discrimination scores separated the manual deaf from the other two groups, particularly when differences in form shapes were involved in the test. The implications of the results for theories relating orosensory-discrimination abilities are discussed. It is postulated that, while a failure in oroperceptual functioning may lead to disorders of articulation, a failure to use the oral mechanism for speech activities, even in persons with normal orosensory capabilities, may result in poor performance on oroperceptual tasks.

Tourists’ and Residents’ Impressions of A Heritage Tourism Site: The Case of Kampong Taman Sari, Indonesia

2014 ◽  
Vol 8 (3) ◽  
pp. 181 ◽  
Author(s):  
Jenny Ernawati ◽  
Gary T. Moore
Keyword(s):  
Heritage Tourism ◽  
Semantic Differential ◽  
The Other ◽  
Measuring Instrument ◽  
Built Heritage ◽  
Other Hand ◽  
Similarities And Differences

The interface between tourism and built heritage is complicated because much built heritage is located in the middle of living communities. Questions arise about how to achieve a balance between the expectations of tourists and the community. To study this question, this paper reports on tourists’ and residents’ impressions of an international heritage tourism site, the Kampong Taman Sari in Indonesia. Using a linear-numeric semantic differential as the measuring instrument and nine consensus photographs of the site as stimuli, the study investigated similarities and differences in impressions between three groups: tourists (international and domestic) and residents. Three principal dimensions were found to underlie impressions of the site: Attractiveness, Organisation, and Novelty. Significant differences were found among all three groups in their impressions of Attractiveness. In terms of impressions of the Organisation of the site, international and domestic tourists have similar impressions but these differ significantly from the impressions of residents. On the other hand, domestic tourists and residents have similar impressions of the Novelty of the site, which is evaluated differently by international tourists.

scholarly journals Black Hole Algorithm for Sustainable Design of Counterfort Retaining Walls

2020 ◽  
Vol 12 (7) ◽  
pp. 2767 ◽  
Author(s):  
Víctor Yepes ◽  
José V. Martí ◽  
José García
Keyword(s):  
Black Hole ◽  
Sustainable Design ◽  
Retaining Walls ◽  
The Other ◽  
Trade Off ◽  
Construction Company ◽  
Geometric Variables ◽  
The Stability ◽  
The Cost ◽  
Black Hole Algorithm

The optimization of the cost and CO 2 emissions in earth-retaining walls is of relevance, since these structures are often used in civil engineering. The optimization of costs is essential for the competitiveness of the construction company, and the optimization of emissions is relevant in the environmental impact of construction. To address the optimization, black hole metaheuristics were used, along with a discretization mechanism based on min–max normalization. The stability of the algorithm was evaluated with respect to the solutions obtained; the steel and concrete values obtained in both optimizations were analyzed. Additionally, the geometric variables of the structure were compared. Finally, the results obtained were compared with another algorithm that solved the problem. The results show that there is a trade-off between the use of steel and concrete. The solutions that minimize CO 2 emissions prefer the use of concrete instead of those that optimize the cost. On the other hand, when comparing the geometric variables, it is seen that most remain similar in both optimizations except for the distance between buttresses. When comparing with another algorithm, the results show a good performance in optimization using the black hole algorithm.

scholarly journals A Fractional SAIDR Model in the Frame of Atangana–Baleanu Derivative

2021 ◽  
Vol 5 (2) ◽  
pp. 32
Author(s):  
Esmehan Uçar ◽  
Sümeyra Uçar ◽  
Fırat Evirgen ◽  
Necati Özdemir
Keyword(s):  
Existence And Uniqueness ◽  
Laplace Transformation ◽  
Cell Phones ◽  
Mobile Network ◽  
The Other ◽  
Banach Fixed Point Theorem ◽  
Propagation Models ◽  
Computer Worms ◽  
Computer Viruses ◽  
The Stability

It is possible to produce mobile phone worms, which are computer viruses with the ability to command the running of cell phones by taking advantage of their flaws, to be transmitted from one device to the other with increasing numbers. In our day, one of the services to gain currency for circulating these malignant worms is SMS. The distinctions of computers from mobile devices render the existing propagation models of computer worms unable to start operating instantaneously in the mobile network, and this is particularly valid for the SMS framework. The susceptible–affected–infectious–suspended–recovered model with a classical derivative (abbreviated as SAIDR) was coined by Xiao et al., (2017) in order to correctly estimate the spread of worms by means of SMS. This study is the first to implement an Atangana–Baleanu (AB) derivative in association with the fractional SAIDR model, depending upon the SAIDR model. The existence and uniqueness of the drinking model solutions together with the stability analysis are shown through the Banach fixed point theorem. The special solution of the model is investigated using the Laplace transformation and then we present a set of numeric graphics by varying the fractional-order θ with the intention of showing the effectiveness of the fractional derivative.

scholarly journals Competing Conventions with Costly Information Acquisition

Games ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 53
Author(s):  
Roberto Rozzi
Keyword(s):  
Information Acquisition ◽  
Evolutionary Model ◽  
Equilibrium Selection ◽  
The Other ◽  
Group Interactions ◽  
Social Coordination ◽  
Long Run ◽  
Stochastic Stability Analysis ◽  
The Stability ◽  
The Cost

We consider an evolutionary model of social coordination in a 2 × 2 game where two groups of players prefer to coordinate on different actions. Players can pay a cost to learn their opponent’s group: if they pay it, they can condition their actions concerning the groups. We assess the stability of outcomes in the long run using stochastic stability analysis. We find that three elements matter for the equilibrium selection: the group size, the strength of preferences, and the information’s cost. If the cost is too high, players never learn the group of their opponents in the long run. If one group is stronger in preferences for its favorite action than the other, or its size is sufficiently large compared to the other group, every player plays that group’s favorite action. If both groups are strong enough in preferences, or if none of the groups’ sizes is large enough, players play their favorite actions and miscoordinate in inter-group interactions. Lower levels of the cost favor coordination. Indeed, when the cost is low, in inside-group interactions, players always coordinate on their favorite action, while in inter-group interactions, they coordinate on the favorite action of the group that is stronger in preferences or large enough.

scholarly journals Effect of data quality on estimates of farm infectiousness trends in the UK 2001 foot-and-mouth disease epidemic

2006 ◽  
Vol 4 (13) ◽  
pp. 235-241 ◽  
Author(s):  
Nicholas J Savill ◽  
Darren J Shaw ◽  
Rob Deardon ◽  
Michael J Tildesley ◽  
Matthew J Keeling ◽  
...  
Keyword(s):  
Mathematical Models ◽  
Data Quality ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Inaccurate Data ◽  
Foot And Mouth ◽  
The Uk ◽  
Parameter Values

Most of the mathematical models that were developed to study the UK 2001 foot-and-mouth disease epidemic assumed that the infectiousness of infected premises was constant over their infectious periods. However, there is some controversy over whether this assumption is appropriate. Uncertainty about which farm infected which in 2001 means that the only method to determine if there were trends in farm infectiousness is the fitting of mechanistic mathematical models to the epidemic data. The parameter values that are estimated using this technique, however, may be influenced by missing and inaccurate data. In particular to the UK 2001 epidemic, this includes unreported infectives, inaccurate farm infection dates and unknown farm latent periods. Here, we show that such data degradation prevents successful determination of trends in farm infectiousness.

scholarly journals The immunological characterization of several human ribonucleases by using primary binding tests

1977 ◽  
Vol 163 (3) ◽  
pp. 419-426 ◽  
Author(s):  
E A Neuwelt ◽  
M Schmukler ◽  
M S Niziak ◽  
P B Jewett ◽  
C C Levy
Keyword(s):  
Human Plasma ◽  
Cross Reaction ◽  
The Other ◽  
Human Pancreas ◽  
Human Tissues ◽  
Antigenic Difference ◽  
Immunological Characterization ◽  
Similarities And Differences

RNAases (ribonucleases), purified from four human tissues, as well as bovine pancreatic RNAase (RNAase A), were studied by immunodiffusion methods and by two different primary binding tests. The enzymes fell into two groups immunologically, those purified from plasma and pancreas in one and those from spleen and liver in the other. No antigenic cross-reaction between the two groups was detected by any of the immunoassays used. There was a slight antigenic cross-reaction between the human and bovine pancreatic RNAases. The liver and spleen RNAases were immunologically identical by all criteria used, whereas a small but consistent antigenic difference between the human plasma and human pancreas enzymes was detected. The significance of this difference between the human plasma and pancreas RNAases is discussed in relation to similarities and differences in their properties.

Sign in / Sign up

Export Citation Format

Share Document