Tag: nevin manimala

Chaos. 2023 Jun 1;33(6):063117. doi: 10.1063/5.0126559.

ABSTRACT

Seasonal effects powerfully shape the population dynamics with periodic climate changes because species naturally adjust their dynamics with seasonal variations. In response to these effects, sometimes population dynamics exhibit synchrony or generate chaos. However, synchronized dynamics enhance species’ persistence in naturally unstable environments; thus, it is imperative to identify parameters that alter the dynamics of an ecosystem and bring it into synchrony. This study examines how ecological parameters enable species to adapt their dynamics to seasonal changes and achieve phase synchrony within ecosystems. For this, we incorporate seasonal effects as a periodic sinusoidal function into a tri-trophic food chain system where two crucial bio-controlling parameters, Allee and refugia effects, are already present. First, it is shown that the seasonal effects disrupt the limit cycle and bring chaos to the system. Further, we perform rigorous mathematical analysis to perform the dynamical and analytical properties of the nonautonomous version of the system. These properties include sensitive dependence on initial condition (SDIC), sensitivity analysis, bifurcation results, the positivity and boundedness of the solution, permanence, ultimate boundedness, and extinction scenarios of species. The SDIC characterizes the presence of chaotic oscillations in the system. Sensitivity analysis determines the parameters that significantly affect the outcome of numerical simulations. The bifurcation study concerning seasonal parameters shows a higher dependency of species on the frequency of seasonal changes than the severity of the season. The bifurcation study also examines the bio-controlling parameters and reveals various dynamic states within the system, such as fold, transcritical branch points, and Hopf points. Moreover, the mathematical analysis of our seasonally perturbed system reveals the periodic coexistence of all species and a globally attractive solution under certain parametric constraints. Finally, we examine the role of essential parameters that contribute to phase synchrony. For this, we numerically investigate the defining role of the coupling dimension coefficient, bio-controlling parameters, and other parameters associated with seasonality. This study infers that species can tune their dynamics to seasonal effects with low seasonal frequency, whereas the species’ tolerance for the severity of seasonal effects is relatively high. The research also sheds light on the correlation between the degree of phase synchrony, prey biomass levels, and the severity of seasonal forcing. This study offers valuable insights into the dynamics of ecosystems affected by seasonal perturbations, with implications for conservation and management strategies.

PMID:37276576 | DOI:10.1063/5.0126559

Chaos. 2023 Jun 1;33(6):063110. doi: 10.1063/5.0147847.

ABSTRACT

This paper designs an algorithm to distill the piecewise non-linear dynamical system from the data without prior knowledge. The system to be identified does not have to be written as a known model term or be thoroughly understood. We exploit the fact that an unknown piecewise non-linear system can be decomposed into the Fourier series as long as its equations of motion are Riemann integrable. Based on this property, we reduce the challenge of finding the correct model to discovering the Fourier series approximation. However, the Fourier series approximation of the piecewise function is inaccurate. The new method takes advantage of this weakness to determine whether the model has piecewise features and to find a way to discover the discontinuity set. Then, the dynamical system on each segment is identified as a pure Fourier series. Identification of intricate models can be achieved in simple steps. The results show that the method can accurately discover the equation of motion and precisely capture the non-smooth characteristic. Next, the prediction and further detailed analysis can be carried out.

PMID:37276571 | DOI:10.1063/5.0147847

Chaos. 2023 Jun 1;33(6):063114. doi: 10.1063/5.0146649.

ABSTRACT

We reinvestigate a paradigmatic model of nonequilibrium statistical physics consisting of an inertial Brownian particle in a symmetric periodic potential subjected to both a time-periodic force and a static bias. In doing so, we focus on the negative mobility phenomenon in which the average velocity of the particle is opposite to the constant force acting on it. Surprisingly, we find that in the weak dissipation regime, thermal fluctuations induce negative mobility much more frequently than it happens if dissipation is stronger. In particular, for the very first time, we report a parameter set in which thermal noise causes this effect in the nonlinear response regime. Moreover, we show that the coexistence of deterministic negative mobility and chaos is routinely encountered when approaching the overdamped limit in which chaos does not emerge rather than near the Hamiltonian regime of which chaos is one of the hallmarks. On the other hand, at non-zero temperature, the negative mobility in the weak dissipation regime is typically affected by weak ergodicity breaking. Our findings can be corroborated experimentally in a multitude of physical realizations, including, e.g., Josephson junctions and cold atoms dwelling in optical lattices.

PMID:37276563 | DOI:10.1063/5.0146649

Chaos. 2023 Jun 1;33(6):063107. doi: 10.1063/5.0120076.

ABSTRACT

The multi-armed bandit (MAB) model is one of the most classical models to study decision-making in an uncertain environment. In this model, a player chooses one of K possible arms of a bandit machine to play at each time step, where the corresponding arm returns a random reward to the player, potentially from a specific unknown distribution. The target of the player is to collect as many rewards as possible during the process. Despite its simplicity, the MAB model offers an excellent playground for studying the trade-off between exploration vs exploitation and designing effective algorithms for sequential decision-making under uncertainty. Although many asymptotically optimal algorithms have been established, the finite-time behaviors of the stochastic dynamics of the MAB model appear much more challenging to analyze due to the intertwine between the decision-making and the rewards being collected. In this paper, we employ techniques in statistical physics to analyze the MAB model, which facilitates the characterization of the distribution of cumulative regrets at a finite short time, the central quantity of interest in an MAB algorithm, as well as the intricate dynamical behaviors of the model. Our analytical results, in good agreement with simulations, point to the emergence of an interesting multimodal regret distribution, with large regrets resulting from excess exploitation of sub-optimal arms due to an initial unlucky output from the optimal one.

PMID:37276557 | DOI:10.1063/5.0120076

Chaos. 2023 Jun 1;33(6):063109. doi: 10.1063/5.0145914.

ABSTRACT

Every successful species invasion is facilitated by both ecological and evolutionary mechanisms. The evolution of population’s fitness related traits acts as functional adaptations to Allee effects. This trade-off increases predatory success at an expense of elevated death rate of potential predators. We address our queries employing an eco-evolutionary modeling approach that provides a means of circumventing inverse density-dependent effect. In the absence of evolution, the ecological system potentially exhibits multi-stable configurations under identical ecological conditions by allowing different bifurcation scenarios with the Allee effect. The model predicts a high risk of catastrophic extinction of interacting populations around different types of saddle-node bifurcations resulting from the increased Allee effect. We adopt the game-theoretic approach to derive the analytical conditions for the emergence of evolutionarily stable strategy (ESS) when the ecological system possesses asymptotically stable steady states as well as population cycles. We establish that ESSs occur at those values of adopted evolutionary strategies that are local optima of some functional forms of model parameters. Overall, our theoretical study provides important ecological insights in predicting successful biological invasions in the light of evolution.

PMID:37276555 | DOI:10.1063/5.0145914

J Med Internet Res. 2023 Mar 5. doi: 10.2196/42840. Online ahead of print.

ABSTRACT

BACKGROUND: The Coronavirus Disease 2019 (COVID-19) pandemic accelerated utilization and acceptance of telemedicine. Simultaneously, Emergency Departments (ED) have experienced significantly increased ED boarding. With this acceptance of telemedicine and the weighty increase in patient boarding we proposed an innovative Virtual First (VF) program to leverage Emergency Medicine Clinicians’ (EMCs) ability to triage patients. VF seeks to reduce unnecessary ED visits by connecting patients with EMCs prior to seeking in-person care rather than utilizing traditional ED referral systems.

OBJECTIVE: The goal of this study is to investigate how patients’ access to EMCs from home via the establishment of VF changed how patients seek care for acute care needs.

METHODS: VF is a synchronous virtual video visit stationed at a tertiary care academic hospital. VF was staffed by EMCs and enabled full management of patient complaints, or if necessary, referral to a primary care physician (PCP), urgent care center (UCC), or ED. Patients self-selected this service as an alternative to seeking in-person care at PCP, UCC or ED. A post-visit convenience sample survey was collected through phone text message or email to VF users. This is a cross- sectional survey study. Primary outcome measure is based on responses to the question, “How would you have sought care if a VF visit was not available to you?” Secondary outcome measures describe valued aspects and criticisms from their visit. Results were analyzed using descriptive statistics.

RESULTS: There were 3097 patients seen via VF from July 2021 through May 2022. 176 of 3097 (5.7%) completed the survey. 87 of 176 (49.4%) would have sought care at UCCs if VF had not been available. Twenty-eight (15.9%), twenty-six (14.8%), and one (0.6%) would have sought care at PCPs, EDs, or other locations, respectively. Interestingly, 34 of 176 (19.3%) of patients would not have sought care. The most valued aspects of VF were receiving care in the comfort of home (137 of 176; 77.8%), availability of appointments (105 of 176; 59.6%), not waiting in a lobby (100 of 176; 56.8%), and decreased infectious exposure (89 of 176; 50.6%). For suggested improvements to VF, 58 of 176 (33.0%) patients free-texted “Nothing”, 47 (26.7%) suggested connectivity improvements, 23 (13.1%) wanted the ability to have lab work or imaging ordered, 14 (8.0%) had to seek medical care after the VF visit , and desired having a doctor perform a physical exam (5.7%).

CONCLUSIONS: VF has potential to restructure how patients seek medical care by connecting EMCs with patients prior to ED arrival. Without the option of VF, 64.2% of patients would have sought care at an acute care facility. VF’s innovative employment of EMCs allows for acute care needs to be treated virtually if feasible. If not, EMCs understand the local resources to better direct patients to the appropriate site. This has potential to substantially decrease patient costs because patients are given the appropriate destination for in-person care, reducing the likelihood of the need for transfer and multiple ED visits.

PMID:37276547 | DOI:10.2196/42840

Acc Chem Res. 2023 Jun 5. doi: 10.1021/acs.accounts.3c00168. Online ahead of print.

ABSTRACT

ConspectusUnderstanding the thermoelectric effects that convert energy between heat and electricity on a molecular scale is of great interest to the nanoscience community. As electronic devices continue to be miniaturized to nanometer scales, thermoregulation on such devices becomes increasingly critical. In addition, the study of molecular thermoelectricity provides information that cannot be accessed through conventional electrical conductance measurements. The field of molecular thermoelectrics aims to explore thermoelectric effects in electrode-molecule-electrode tunnel junctions and draw inferences on how the (supra)molecular structure of active molecules is associated with their thermopower. In this Account, we introduce a convenient and useful junction technique that enables thermovoltage measurements of one molecule thick films, self-assembled monolayers (SAMs), with reliability, and discuss the atomic-detailed structure-thermopower relations established by the technique. The technique relies on a microelectrode composed of non-Newtonian liquid metal, eutectic gallium-indium (EGaIn) covered with a native gallium oxide layer. The EGaIn electrode makes it possible to form thermoelectric contacts with the delicate structure of SAMs in a noninvasive fashion. A defined interface between SAM and the EGaIn electrode allows time-effective collection of large amounts of thermovoltage data, with great reproducibility, efficiency, and reliable interpretation and statistical analysis of the data. We also highlight recent efforts to utilize the EGaIn technique for probing molecular thermoelectricity and structure-thermopower relations. Using the technique, it was possible to unravel quantum-chemical mechanisms of thermoelectric functions, based on the Mott formula, in SAM-based large-area junctions, which in turn led us to set various hypotheses to boost the Seebeck coefficient. By validating the hypotheses again with the EGaIn technique, we revealed that the thermopower of junction increases through the reduction of the energy offset between accessible molecular orbital energy level and Fermi level or the tuning of broadening of the orbital energy level. Such alterations in the shape of energy topography of junction could be achieved through structural modifications in anchoring group and molecular backbone of SAM, and the bottom electrode. Molecular thermoelectrics offers a unique opportunity to build a well-defined nanoscale system and isolate an effect of interest from others, advancing fundamental understanding of charge transport across individual molecules and molecule-electrode interfaces. In the Account, we showed our recent work involving carefully designed molecular system that are relevant to answering the question of how thermopower differs between the tunneling and thermal-hopping regimes. The field of molecular thermoelectrics needs to address practical application-related issues, particularly molecular degradation in thermal environments. In this regard, we summarized the results highlighting the thermal instability of SAM-based junctions based on a traditional thiol anchor group and how to circumvent this problem. We also discussed the power factor (PF)─a practical parameter representing the efficiency for converting heat into electricity─of SAMs, evaluated using the EGaIn technique. In the Conclusion section of this Account, we present future challenges and perspectives.

PMID:37276526 | DOI:10.1021/acs.accounts.3c00168

Heliyon. 2023 May 19;9(6):e16317. doi: 10.1016/j.heliyon.2023.e16317. eCollection 2023 Jun.

ABSTRACT

Inappropriate variety use in different agroecology is one of the primary issues which significantly affect garlic phenotype, growth, yield, and nutritional quality. For this reason, a trial was done during the 2022 main season at the demonstration site of Bule Hora University, to see the impact of genotypes on phenotype, growth, yield-related attributes, and nutritional quality of garlic. The experiment was composed of four varieties namely Kuriftu, Holleta, Chafe, Tsedey 92, and one local cultivar. The trial was set up in a randomized complete block design replicated four times. The output showed that garlic varieties statistically (p < 0.05) affected all phenotype, growth, yield-related attributes, and nutritional qualities. Using a variety of Holleta and kuriftu minimize days of emergence by 9.82 and 10.33 days after planting and 75% physiological maturity by 23.6 and 25.90 days after planting, respectively, beyond variety Tsedey 92. The highest marketable bulb yield (8.21 t/ha, and 8.18 t/ha) was observed from Kuriftu and Holleta, respectively. While the lowest (4.39 t/ha) was from Tsedey 92. The highest Ash, energy, and carbohydrate were recorded from Kuriftu and Holleta, while the least from the Local cultivar. However, the highest moisture content, protein, and fat were observed from local cultivars, while the least from Kuriftu, and Holleta. In general, garlic varieties significantly affected all the phenotype, growth, bulb yield-related, and Nutritional quality. Therefore, it can be concluded that using the variety Kuriftu, and Holleta at Bule Hora agroecology is suggested to boost early germination, better performance, marketable bulb yield, and nutritional quality of garlic.

PMID:37274705 | PMC:PMC10238683 | DOI:10.1016/j.heliyon.2023.e16317

Heliyon. 2023 May 23;9(6):e16362. doi: 10.1016/j.heliyon.2023.e16362. eCollection 2023 Jun.

ABSTRACT

Based on the implementation of the third stage of “Three-year Action Plan for Preschool Education”, this research took preschool education resources of 31 provinces (cities), autonomous regions (excluding Hong Kong, Macao and Taiwan) and municipalities in China from 2003 to 2019 as research samples. At the same time, according to the data of Educational Statistics Yearbook of China (2003-2019) and China Educational Finance Statistics Yearbook (2004-2020), this research collected the data of preschool education human resources, material resources, and financial resources. As for the data analysis, this research was based on the methodology of entropy method, repeated indicators method, and the Theil index and so on, and evaluated the state of preschool education resources allocation in China from 2003 to 2019. Simultaneously, according to the state of preschool education resources allocation, this research analyzed the spatio-temporal differences of preschool education resources allocation between various provinces and various areas, then analyzed the causes of spatio-temporal differences. After that, suggestions were put forward according to the analysis. The results show that, since the implementation of the third stage of “Three-year Action Plan for Preschool Education“, the condition of preschool education resources allocation has been generally improved. However the preschool education resources allocation still presents a low-level and uneven development trend. Preschool education resources have formed a “preschool education resource advantage belt” in Beijing, Tianjin and the Yangtze River Delta; Comparing with material resources, the development of human resources in preschool education lags behind in China; In terms of each regions in China, eastern China has the most significant difference in the preschool education resources allocation, which is followed by western China, and inner China has the least significant difference; The main factor affecting the regional preschool education resources allocation difference is the inter-provincial differences in eastern China, inner China, and western China; And the main factors affecting the differences in preschool education resources in eastern, inner, and western China are respectively financial resources, human resources, and financial resources. At the same time, financial resources in eastern China and human resources in inner China tend to expand. Based on this, this study proposes methods to narrow the regional differences in preschool education resources allocation, so as to provide references for realizing preschool education equity and preschool education sustainable development.

PMID:37274700 | PMC:PMC10238904 | DOI:10.1016/j.heliyon.2023.e16362

Heliyon. 2023 May 23;9(6):e16441. doi: 10.1016/j.heliyon.2023.e16441. eCollection 2023 Jun.

ABSTRACT

Offshore operations are generally challenging and hazardous, and the workers are exposed to conditions that may lead to fatigue. A cross-sectional study evaluated physical and psychological job demands and their associations with fatigue among offshore workers. The offshore workers (n = 251) completed a questionnaire including demographic/job details, Multidimensional Fatigue Inventory (MFI‒20), and Job Content Questionnaire (JCQ). Data were analysed using linear regression modelling. Results indicated that the physical (particularly performing repetitive motions and applying pressure with hands and wrists) and psychological (e.g., intense task concentration and fast working) job demands were relatively high. The total mean (SD) fatigue score (MFI‒20) was 56.3 (13.9). Individual factors (Body Mass Index ‒ BMI), physical job demands (awkward working postures, frequent moving/lifting heavy objects and doing lots of physical efforts) and psychological job demands (task interruptions by other people and doing an excessive amount of work) were the main variables associated with different dimensions of fatigue in the multivariate models. While physical fatigue was only associated with the physical job demands, both physical and psychological job demands were significantly associated with mental fatigue in the multivariate context. The findings have possible implications for job design and implementation of intervention programmes to promote health and performance of the employees.

PMID:37274697 | PMC:PMC10238685 | DOI:10.1016/j.heliyon.2023.e16441