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In chaotic dynamical systems such as the weather, prediction errors grow faster in some situations than in others. Real-time knowledge about the error growth could enable strategies to adjust the modelling and forecasting infrastructure on-the-fly to increase accuracy or reduce computation time. One could, e.g., change the ensemble size, or the distribution and type of target observations. Local Lyapunov exponents are known indicators of the rate at which very small prediction errors grow over a finite time interval. However, their computation is very expensive: it requires maintaining and evolving a tangent linear model, orthogonalisation algorithms and storing large matrices. In this feasibility study, we investigate the accuracy of supervised machine learning in estimating the current local Lyapunov exponents, from input of current and recent time steps of the system trajectory, as an alternative to the classical method. Thus machine learning is not used here to emulate a physical model or some of its components, but non intrusively as a complementary tool. We test four popular supervised learning algorithms: regression trees, multilayer perceptrons, convolutional neural networks and long short-term memory networks. Experiments are conducted on two low-dimensional chaotic systems of ordinary differential equations, the R\"ossler and the Lorenz 63 models. We find that on average the machine learning algorithms predict the stable local Lyapunov exponent accurately, the unstable exponent reasonably accurately, and the neutral exponent only somewhat accurately. We show that greater prediction accuracy is associated with local homogeneity of the local Lyapunov exponents on the system attractor. Importantly, the situations in which (forecast) errors grow fastest are not necessarily the same as those where it is more difficult to predict local Lyapunov exponents with machine learning., Comment: 37 pages, 10 Figures

Chao merupakan produk fermentasi tradisional dari daerah Sulawesi Selatan dengan bahan baku ikan tembang, garam dan nasi yang difermentasi dengan ragi tape dan ragi tempe. Penelitian ini menggunakan bakteri asam laktat (BAL) proteolitik Lactobacillus plantarum Ags1-3 dan P. acidilactici Ags7-3 sebagai co-starter untuk mempelajari perananan dan potensinya sebagai penghasil ACE inhibitor selama fermentasi chao ikan tembang. Penelitian ini terdiri dari tiga tahap yaitu fermentasi garam (20%) (A-B), fermentasi BAL (C-D), dan fermentasi campuran BAL dengan nasi terfementasi (E-F). Sebagai kontrol adalah chao yang difermentasi tanpa penambahan inokulum BAL. Selama fermentasi diamati kadar garam, aktivitas air, populasi mikroorganisme, produksi asam dan perubahan pH serta kadar protein terlarut dan aktivitas inhibitor Angiotensin Converting Enzyme (ACE). Hasil penelitian menunjukkan bahwa pada fermentasi garam (A-B) terjadi kenaikan kadar garam pada ikan tembang dari 10,75% menjadi 16,48% dan tidak terjadi pertumbuhan mikroorganisme pada tahap ini. Pada tahap fermentasi BAL (C-D), terjadi kenaikan jumlah bakteri dan total BAL lebih dari 2 siklus log, namun pada kontrol, jumlah bakteri dan total BAL lebih rendah. BAL proteolitik mendegradasi protein menjadi komponen yang lebih sederhana yang ditandai dengan kenaikan yang nyata pada kadar protein terlarutnya dan tidak terjadi penurunan pH. Isolat BAL proteolitik berpotensi menghasilkan inhibitor ACE yang ditandai dengan aktivitas ACE-I mencapai 84-85%, sedang pada kontrol, aktivitas penghambatan ACE pada ikan yang difermentasi hanya 58%. Pada fermentasi campuran (E-F) terjadi peningkatan produksi asam dan penurunan pH yang nyata karena tersedianya sumber karbon yang berasal dari nasi terfermentasi. Fermentasi chao tanpa penambahan inokulum juga terjadi penurunan pH, namun nilai pHnya lebih tinggi. Fermentasi chao dengan penambahan inokulum BAL proteolitik berpotensi menghasilkan aktivitas penghambatan ACE dan dapat memperpendek waktu fermentasi.

As pointed out by many researchers, replication plays a key role in the credibility of applied sciences and the confidence in all research findings. With regard, in particular, to energy finance and economics, replication papers are rare, probably because they are hampered by inaccessible data, but their aim is crucial. We consider two ways to avoid misleading results on the ostensible chaoticity of price series. The first one is represented by the proper mathematical definition of chaos and the related theoretical background, while the latter is represented by the hybrid approach that we propose here—i.e., consisting of considering the dynamical system underlying the price time series as a deterministic system with noise. We find that both chaotic and stochastic features coexist in the energy commodity markets, although the misuse of some tests in the established practice in the literature may say otherwise.

We investigated the behavior of a Susceptible-Infected-Recovered seasonally forced model for endemic childhood infectious diseases in the case where the target population is not isolated and, moreover, fast weekly fluctuations of the social contacts occur. We considered some key scenarios of interplay of Susceptible subjects with the external world, leading to subharmonic resonances and chaos. Our simulations suggest that the above–mentioned fast oscillations of the contact rate can cause the suppression/reduction of chaos and of subharmonic resonances. Thus, far from being filtered, they have an important role. If one considers an opposition of phase of the pattern of external infections w.r.t. the pattern of internal transmission rate, they result remarkably different from a scenario of synchrony. In most scenarios, the chaotic behavior is not associated to the phenomenon of the ‘atom–infectious’, i.e. the proportion of infectious is small but not unrealistic for large populations. published

This text is based on a conversation between members in the Brazilian Landless Workers Movement, a film producer and a media and communication researcher about the production process of the documentary Chão (Landless). Chão documents MST’s processes of land occupation and the battles to gain rights to land in the state of Goiás between 2014 and 2018. MST’s mobilization practices since the emergence of the Movement in 1984 have been much informed by Paulo Freire’s emancipatory pedagogy. The Movement’s historically situated social action constructs knowledge about reality at the same time that it changes reality. The documentary is an example of participatory media production in which the filmmaker and the militants constructed a narrative together from their different perspectives. This participatory process is used here as a departure point to discuss the experiential dynamics of the conscientization process from the different perspectives of research, media production, and militancy. Este texto se basa en una conversación entre miembros del Movimiento de Trabajadores sin Tierra de Brasil (MST), una directora de cine y una investigadora en comunicación sobre el proceso de producción del documental Chão (Landless). Chão documenta los procesos de ocupación de tierras del MST y las luchas para conseguir derechos sobre la tierra en el estado de Goiás entre 2014 y 2018. Las prácticas de movilización del MST desde el surgimiento del Movimiento en 1984 han estado muy influidas por la pedagogía emancipadora de Paulo Freire. La acción social históricamente situada del Movimiento construye conocimiento sobre la realidad al mismo tiempo que la cambia. El documental es un ejemplo de producción de medios participativos en el que el cineasta y los militantes construyeron juntos una narrativa desde sus diferentes perspectivas. Este proceso participativo se usa aquí como punto de partida para discutir la dinámica experiencial del proceso de concientización desde las diferentes perspectivas de investigación, producción de medios y militancia.

Nurhikmayani R, Daryono BS, Retnaningrum E. 2019. Isolation and molecular identification of antimicrobial-producing Lactic Acid Bacteria from chao, South Sulawesi (Indonesia) fermented fish product. Biodiversitas 20: 1063-1068. Chao is traditional fermented fish made of anchovy (Stolephorus sp.), rice, salt, and fermented naturally on controlled environment. The product comes from Pangkep Regency, South Sulawesi. Chao has the potential for the source of high-grade lactic acid bacteria isolates, especially for antimicrobial compound. Antimicrobial compound produced by lactic acid bacteria is a biopreservative compound with many advantages. The purposes of this investigation were to isolate antimicrobial-producing lactic acid bacteria from chao and to identify their isolates based on the molecular properties. Lactic acid bacteria were isolated from chao using Man Ragosa Sharpe Agar (MRSA) medium added with 0.1 % CaCO3, followed by the ability test to produce antimicrobial compound against Staphylococcus aureus FNCC 0047 as an indicator. The spectrum of crude antimicrobial as cell-free supernatant (CFS) was determined by antagonism against S. aureus FNCC 0047 and Escherichia coli FNCC 0049 on agar well diffusion test. Selected isolates of antimicrobial-producing lactic acid bacteria molecularly identified from 16S rRNA marker using primer 27F and 1492R. We obtained four isolates of lactic acid bacteria that showed the antimicrobial activity. This crude antimicrobial compound could inhibit both gram-positive Staphylococcus aureus FNCC0047 and gram-negative bacteria Escherichia coli FNCC0049. The highest crude antimicrobial activity of isolates was observed on IB1C strain. The results of molecular characterization suggested that the IB1C and IB3B strain were identified as Lactobacillus plantarum, whereas IB3E and IB3F were identified as Pediococcus pentosaceus.

Mathematical models based on fractional-order differential equations have recently gained interesting insights into epidemiological phenomena, by virtue of their memory effect and nonlocal nature. This paper investigates the nonlinear dynamic behavior of a novel COVID-19 pandemic model described by commensurate and incommensurate fractional-order derivatives. The model is based on the Caputo operator and takes into account the daily new cases, the daily additional severe cases, and the daily deaths. By analyzing the stability of the equilibrium points and by continuously varying the values of the fractional order, the paper shows that the conceived COVID-19 pandemic model exhibits chaotic behaviors. The system dynamics are investigated via bifurcation diagrams, Lyapunov exponents, time series, and phase portraits. A comparison between integer-order and fractional-order COVID-19 pandemic models highlights that the latter is more accurate in predicting the daily new cases. Simulation results, besides to confirming that the novel fractional model well fit the real pandemic data, also indicate that the numbers of new cases, severe cases, and deaths undertake chaotic behaviors without any useful attempt to control the disease. Supplementary Information The online version supplementary material available at 10.1007/s11071-021-06867-5.

The gravitational potentials of realistic galaxy models are in general non-integrable, in the sense that they admit orbits that do not have three independent isolating integrals of motion and are therefore chaotic. However, if chaotic orbits are a small minority in a stellar system, it is expected that they have negligible impact on the main dynamical properties of the system. In this paper we address the question of quantifying the importance of chaotic orbits in a stellar system, focusing, for simplicity, on axisymmetric systems. Chaotic orbits have been found in essentially all (non-St\"ackel) axisymmetric gravitational potentials in which they have been looked for. Based on the analysis of the surfaces of section, we add new examples to those in the literature, finding chaotic orbits, as well as resonantly trapped orbits among regular orbits, in Miyamoto-Nagai, flattened logarithmic and shifted Plummer axisymmetric potentials. We define the fractional contributions in mass of chaotic ($\xi_{\rm c}$) and resonantly trapped ($\xi_{\rm t}$) orbits to a stellar system of given distribution function, which are very useful quantities, for instance in the study of the dispersal of stellar streams of galaxy satellites. As a case study, we measure $\xi_{\rm c}$ and $\xi_{\rm t}$ in two axisymmetric stellar systems obtained by populating flattened logarithmic potentials with the Evans ergodic distribution function, finding $\xi_{\rm c}\sim 10^{-4}-10^{-3}$ and $\xi_{\rm t}\sim 10^{-2}-10^{-1}$., Comment: Accepted for publication in MNRAS. 15 pages, 11 figures

Physical implementation of asynchronous cellular automata networks has shown stably random oscillations under certain conditions. We present two simple mathematical models to describe transient and stationary regimes. The models are based on simple assumptions taking into account several aspects such as number of inputs of the cellular automata, rule balance, and technological frequency limitation. Numerical simulations reveal the possibility of chaotic dynamics of the average transition rate of the cellular automata in a stationary regime. With physical implementations on FPGA (field programmable gate array), preliminary experimental results show very good qualitative agreement with model’s prediction and numerical simulations. Several networks of interconnected 5-input asynchronous cellular automata have been successfully implemented in different FPGA devices, and we present some preliminary experimental results. This work aims at finding fundamental mechanisms of randomness such that the collective behavior of the cellular automata system does not depend on physical implementation details.

Nonlinearity in Quantum Mechanics may have extrinsic or intrinsic origins and is a liable route to a chaotic behaviour that can be of difficult observations. In this paper, we propose two forms of nonlinear Hamiltonian, which explicitly depend upon the phase of the wave function and produce chaotic behaviour. To speed up the slow manifestation of chaotic effects, a resonant laser field assisting the time evolution of the systems causes cumulative effects that might be revealed, at least in principle. The nonlinear Schr&ouml, dinger equation is solved within the two-state approximation, the solution displays features with characteristics similar to those found in chaotic Classical Mechanics: sensitivity on the initial state, dense power spectrum, irregular filling of the Poincar&eacute, map and exponential separation of the trajectories of the Bloch vector &sigma, in the Bloch sphere.

In this paper we consider some piecewise smooth 2-dimensional systems having a possibly non-smooth homoclinic γ → ( t ) . We assume that the critical point 0 → lies on the discontinuity surface Ω 0 . We consider 4 scenarios which differ for the presence or not of sliding close to 0 → and for the possible presence of a transversal crossing between γ → ( t ) and Ω 0 . We assume that the systems are subject to a small non-autonomous perturbation, and we obtain 4 new bifurcation diagrams. In particular we show that, in one of these scenarios, the existence of a transversal homoclinic point guarantees the persistence of the homoclinic trajectory but chaos cannot occur. Further we illustrate the presence of new phenomena involving an uncountable number of sliding homoclinics.

Pressure swirl sprays are frequently used in burners for gas turbines like the LPP chamber or to generate diffusion flames. Combustion between fuel and the air is governed by complex phenomena determined by the mixing of the mass flow rate of the two phases liquid and gaseous. Characterization of the spray by measuring the half cone angle fluctuations with a speed camera and a Lagrangian approach allows the working space of the spray to be defined and the “signature” of the spray in well-defined conditions of supply pressure to be identified. The results define the pseudo-chaotic structure of the spray and highlight behavior affecting the combustion process.

This article represents an attempt to characterise the dynamics of a nonlinear duopoly with price competition and horizontal product differentiation by accounting for non-negativity constraints (on profits and the market demand). The model is set up by following the tradition led by Bischi et al. (1998), according to which players have limited information. The article shows several local and global phenomena of a two-dimensional discrete time system when the price demand elasticity varies. It also points out the differences from both a mathematical and economic point of views in terms of dynamic outcomes when the non-negativity constraints are not binding and when they are binding. This is done by combining mathematical techniques and simulation exercises.

The purpose of the chapter is to gain a better understanding of energy market movements and dynamics by examining two competing theories: deterministic chaos theory and stochastic paradigm.We advocate that feature of bothworldsmay coexist in the same phenomenon. In particular, we reassess the chaotic paradigm, by considering the advances that have been made in the design of estimation tools. We illustrate all the methodologies exploited in the energy finance literature and the related results.

The spontaneous capacity to produce ideas is a focal dimension of our life. It is generally agreed that creativity (a manifestation of structure and functional brain processes) defines the potential of society, and it has been explored in several aspects (e.g. from physiological, social, psychological, developmental, cognitive, and historical perspectives). Actually, if the brain is the object of investigation of the cognitive science and thus neuroscience, creativity is an integral part of human achievement and social and technological development. Over the years, it has been hard to create research protocols that associate both lines, though recently attempts have been made to connect those issues, exploring the benefits of a transdisciplinary methodology. Aim of this work is to explain the biological basis of creativity processes in order to highlight possible developments of ICT technologies to simulate, support and empowering its complex pathways.

This work attempts to characterise the dynamic properties of a nonlinear model in which a monopolist produces a fixed amount of an intermediate good. The firm employs this good in producing two vertically differentiated final commodities, sold in two distinct markets. Consumers’ preferences are described by quasi-linear and quadratic utility functions respectively yielding isoelastic and linear demand functions. In addition, we assume that the monopolist adopts a gradient adjustment rule based on profit variation to adjust its choice about the amount of intermediate good to employ in the production of each final good. Two alternative scenarios emerge: in the first, there exists coexistence of two markets; in the second, the monopolist specialises on the production of a single final good. The dynamics show that the elasticities of market demands play an ambiguous role in affecting the stability of the equilibrium, whereas the speed of adjustment unambiguously destabilises the system. Moreover, the article investigates the role of the productive capacity and the gap in marginal costs in defining the different scenarios. In particular, economic dynamics may be chaotic and/or multiple attractors may appear.

Two counterexamples, addressing questions raised in Adamczak (2019) and Poly and Zheng (2019), are provided. Both counterexamples are related to chaoses. Let F n = Y n + Z n , where the random variables Y n and Z n belong to different chaoses of uniformly bounded degree. It may be that F n ⟶ a . s . 0 , F n ⟶ L 2 + δ 0 and E { sup n | F n | δ } ∞ , for some δ > 0 , and yet Y n fails to converge to 0 a.s.

En el presente trabajo se determinó la riqueza de especies de escarabajos coprófagos en tres remanentes boscosos en tres áreas con condiciones ecológicas distintas: bosque primario maduro, fragmentos de bosque dentro de áreas agropecuarias y zonas deforestadas dentro de la Reserva Forestal Natural de Vanguardia en el municipio de Villavicencio. En cada una de las tres zonas definidas se hicieron tres muestreos en diferentes fechas, que consistieron en diez trampas de caída, 5 cebadas con heces de vaca intercaladas con 5 con heces humanas, dispuestas cada 100 metros en un transecto de un kilómetro de longitud. Los individuos recolectados se identificaron hasta género. Se calcularon índices de riqueza biológica como Chao y Jackknife, índices de diversidad y dominancia como Shannon-Wierner y Simpson para calcular la variedad de géneros en el área de estudio; de igual forma se identificó la relación y similitud de las muestras mediante el índice de Jaccard. Del esfuerzo de muestreo se logró colectar 194 individuos pertenecientes a 14 géneros de la familia Scarabaeidae que representa entre el 82 y el 100% de los géneros presentes en el área de acuerdo a los estimados de Jacknife y Chao respectivamente. Se encontró que en el bosque primario y en los fragmentos los 14 géneros y los indicadores mostraron una alta riqueza de especies y baja dominancia. En la zona deforestada solamente se encontraron tres de los 14 géneros y los indicadores mostraron una baja riqueza de especies, pero una alta dominancia. En las zonas forestadas se encontraron en abundancia los géneros Gromphas y Eurysternus que son típicas de bosques en buen estado, el número de capturas fue significativamente mayor en la zona de bosque primario extenso que en la zona de bosque fragmentado, estos géneros no fueron encontrados en las zonas deforestadas. Sylvicanthon, que es un género que se adapta mejor a todo tipo de condición, fue encontrado tanto en las zonas forestadas como en las deforestadas. Se encontró que todos los géneros fueron colectados en trampas cebadas con heces de vaca o de humano; sin embargo, en las trampas con heces humanas el número de individuos capturados fue mucho mayor. In the present work, the richness of coprophagous beetle species in remnant forest was determined at one area with different ecological conditions: primary old forest, fragmented forest and deforested areas within the Vanguardia Natural Forest Reserve at Villavicencio´s City. In each of them we made three samples, each sample consisted of a transect of 1 km, with pitfall traps, baited with cow and human feces, and in each transect five traps used cow feces and five with Human stool; those traps were interspersed. The collected specimens will be identified until gender level. Wealth indices such as Chao and Jackknife are calculated, indices of diversity and dominance such as Shannon-Wierner and Simpson to calculate the variety of genres in the study area; similarly, the relationship and similarity of the samples is identified through the Jaccard index. The sampling effort was divided to collect 194 specimens belonging to 14 genders of the Scarabaeidae family that represents between 82 and 100% of the genera present in the area according to the estimates of Jacknife and Chao, respectively. It was found that in the primary old forest and at fragmented forest. At deforested area we just found three of the 14 genders and indicators of low species richness, but higher dominance. In the forested areas, the genders called Gromphas and Eurysternus, which are typical in places with good conditions; Those genders were found in abundance, the number of catches became the area of extensive primary forest, and in the zone of fragmented forest, these genders were not found. Sylvicanthon, which is a genus that best adapts to all types of conditions, has been found in all of the areas. It was found that all of genders were collected in traps with cow or human feces; However, in the traps with the number of individuals captured was much more important. Ingeniero Ambiental http://unidadinvestigacion.usta.edu.co Pregrado

In modern societies the main sources of information are Internet-based social networks. Thus, the opinion of citizens on key topics, such as vaccines, is very volatile. Here, we explore the impact of volatility on the modelling of public response to vaccine awareness campaigns for favouring vaccine uptake. We apply a quasi-steady-state approximation to the model of spread and control of Susceptible-Infected-Removed diseases proposed in (d’Onofrio et al., PLoS One, 2012). This allows us to infer and analyze a new behavioural epidemiology model that is nonlinear in the control. Then, we investigate the efficient design of vaccine awareness campaigns by adopting optimal control theory. The resulting problem has important issues: (i) the integrand of its objective functional is non-convex; (ii) the application of forward-backward sweep (FBS) and gradient descent algorithms in some key cases does not work; (iii) analytical approaches provide continuous solutions that cannot rigorously be implemented since Public Health interventions cannot be fully flexible. Thus, on the one hand, we resort to direct optimization of the objective functional via heuristic stochastic optimization, in particular via particle swarm optimization and differential evolution algorithms. On the other hand, we investigate the non-convergence of the FBS algorithm with tools of the statistical theory of nonlinear chaotic time-series. Finally, since the direct optimization algorithms are stochastic, we provide a statistical assessment of the obtained solutions.

Understanding the functional relationship between the sample size and the performance of species richness estimators is necessary to optimize limited sampling resources against estimation error. Nonparametric estimators such as Chao and Jackknife demonstrate strong performances, but consensus is lacking as to which estimator performs better under constrained sampling. We explore a method to improve the estimators under such scenario. The method we propose involves randomly splitting species‐abundance data from a single sample into two equally sized samples, and using an appropriate incidence‐based estimator to estimate richness. To test this method, we assume a lognormal species‐abundance distribution (SAD) with varying coefficients of variation (CV), generate samples using MCMC simulations, and use the expected mean‐squared error as the performance criterion of the estimators. We test this method for Chao, Jackknife, ICE, and ACE estimators. Between abundance‐based estimators with the single sample, and incidence‐based estimators with the split‐in‐two samples, Chao2 performed the best when CV 0.65, given that the ratio of sample size to observed species richness is greater than a critical value given by a power function of CV with respect to abundance of the sampled population. The proposed method increases the performance of the estimators substantially and is more effective when more rare species are in an assemblage. We also show that the splitting method works qualitatively similarly well when the SADs are log series, geometric series, and negative binomial. We demonstrate an application of the proposed method by estimating richness of zooplankton communities in samples of ballast water. The proposed splitting method is an alternative to sampling a large number of individuals to increase the accuracy of richness estimations; therefore, it is appropriate for a wide range of resource‐limited sampling scenarios in ecology.