It is shown that a relatively simple dynamical dc electric arc model shows complicated two-parameter (2-D) bifurcations with both periodic and chaotic responses. 2-D bifurcation diagrams for the arc ...model a system of three ordinary differential equations (ODEs) are obtained by using parallel computations because obtaining a single 2-D diagram requires solving the ODE system hundreds of thousands or even a few millions of times (depending on the intervals of parameters and assumed resolution). Several color 2-D bifurcation diagrams are presented, and the speedup factors of their parallel computations are provided. Numerical computations of periodic and chaotic responses of the 2-D bifurcation diagrams are confirmed by both the one-parameter (1-D) diagrams and the 0-1 test for chaos . Some further theoretical aspects of parallel computing of 2-D bifurcation diagrams are also considered.
Mathematical analysis of the memristive properties of a full-wave diode rectifier is presented in this Letter. Proofs of the rectifier's three memristive fingerprints are provided in the context of a ...pinched hysteretic current–voltage characteristic of the rectifier.
This paper proposes new methods of computing 2D bifurcation diagrams for nonlinear time series using MultiLayer Perceptrons (MLPs), LSTM Fully Convolutional Networks (LSTM-FCN), Time Series Forests ...(TSFs) with entropy, Gini impurity, and K-Nearest Neighbors (KNNs) algorithm with Dynamic Time Warping (DTW). The proposed algorithms can precisely compute 2D bifurcation diagrams for oscillatory time-series (periodic or chaotic) obtained either as solutions of nonlinear systems of ordinary differential equations (ODEs) or measured and recorded when a mathematical model is not known. Illustrative computational examples include chaotic electric arc RLC circuits. The obtained results confirm usefulness of the proposed methods in a creation of 2D bifurcation diagrams — color images representing dynamics of nonlinear processes, circuits or systems.
•Machine learning can successfully classify time series responses of nonlinear systems.•The supervised methods reconstruct diagrams with great accuracy.•K-Nearest Neighbors and Time Series Forests perform better than other algorithms.
, known as Greater Celandine, is a latex-bearing plant that has been leveraged for its anticancer and antimicrobial properties. Herein,
aerial tissue is mined for the presence of antimicrobial ...peptides. A highly abundant cysteine-rich peptide with a length of 25 amino acids, deemed CM-AMP1, is characterized through multiple mass spectrometric approaches. Electron-activated dissociation is leveraged to differentiate between isoleucine and leucine residues and complement conventional collision-induced dissociation to gain full sequence coverage of the full-length peptide. CM-AMP1 shares little sequence similarity with any proteins in publicly available databases, highlighting the novelty of its cysteine landscape and core motif. The presence of three disulfide bonds in the native peptide confers proteolytic stability, and antimicrobial activity is greatly decreased upon the alkylation of the cysteine residues. Synthetic variants of CM-AMP1 are used to confirm the activity of the full-length sequence and the core motif. To assess the biological impact,
was grown in a sublethal concentration of CM-AMP1 and quantitative proteomics was used to identify proteins produced by the bacteria under stress, ultimately suggesting a membrane lytic antimicrobial mechanism of action. This study integrates multiple analytical methods for molecular and biological characterization of a unique antimicrobial peptide identified from
The emergence of rapidly evolving multidrug-resistant pathogens and a deficit of new compounds entering the clinical pipeline necessitate the exploration of alternative sources of antimicrobial ...therapeutics. Cyclotides revealed in
. are a class of highly stable, cyclic, and disulfide-bound peptides with diverse intrinsic bioactivities. Herein we have identified a novel complement of 42 putative cyclotide masses in the plant species
. Cyclotide-containing fractions of a
peptide library revealed potent bioactivities against the Gram-negative bacteria
ATCC 25922 and the highly virulent and multidrug-resistant
VK148. As such, six previously uncharacterized cyclotides, cycloviolacins I1-6 (cyI1-cyI6), were prioritized for molecular characterization. Cyclotides cyI3-cyI6 contain a novel "TLNGNPGA" motif in the highly variable loop six region, expanding the already substantial sequence diversity of this peptide class. Library fractions comprised of cyclotides cyI3-cyI6 exhibited MIC values of 18 and 35 μM against
and
, respectively, whereas isolated cyI3 killed ∼50% of
at 60 μM and isolated cyI4 demonstrated no killing at concentrations >60 μM against both pathogens. This work expands the repertoire of bioactive cyclotides found in
. and highlights the potential of these antibacterial cyclic peptides.
This paper examines the oscillatory responses (periodic and chaotic) of a biosystem store model for bursting and complex Ca2+ oscillations in which three compartments have been taken into ...consideration: the cytosol, endoplasmic reticulum (ER) and mitochondria. The oscillatory model is used to examine the reliability of the 0-1 test for chaos in the bifurcation analysis of continuous signals obtained when the frequencies of oscillatory responses vary significantly with a relatively small changes of the bifurcation parameters. The illustrative examples in both the one- and two-parameter cases are designed to show that for a periodic time-series the test’s reliability may be questioned when a periodic series is classified as a chaotic one - the ’false-positive’ case. To prevent the incorrect result an additional computational work is needed to examine the frequency spectrum of the periodic time-series. The illustrative examples utilize an autonomous dynamical model of cytosolic calcium oscillations with three dynamical variables and sixteen parameters. The dynamical model is such that the frequency of oscillations may change by the factor of about 200, when a certain dynamical system’s parameter changes from its minimum to maximum values, making selection of the parameters in the 0-1 test extremely difficult. The extra computational work improves the test’s reliability and eliminates the ’false-positive’ outcomes of the test. The paper is focused on the computational aspects of the 0-1 test for periodic and chaotic oscillations rather than on the properties of the store model for bursting and complex Ca2+ oscillations.
There have been significant advances in the flexibility and power of
cell-free translation systems. The increasing ability to incorporate noncanonical amino acids and complement translation with ...recombinant enzymes has enabled cell-free production of peptide-based natural products (NPs) and NP-like molecules. We anticipate that many more such compounds and analogs might be accessed in this way. To assess the peptide NP space that is directly accessible to current cell-free technologies, we developed a peptide parsing algorithm that breaks down peptide NPs into building blocks based on ribosomal translation logic. Using the resultant data set, we broadly analyze the biophysical properties of these privileged compounds and perform a retrobiosynthetic analysis to predict which peptide NPs could be directly synthesized in augmented cell-free translation reactions. We then tested these predictions by preparing a library of highly modified peptide NPs. Two macrocyclases, PatG and PCY1, were used to effect the head-to-tail macrocyclization of candidate NPs. This retrobiosynthetic analysis identified a collection of high-priority building blocks that are enriched throughout peptide NPs, yet they had not previously been tested in cell-free translation. To expand the cell-free toolbox into this space, we established, optimized, and characterized the flexizyme-enabled ribosomal incorporation of piperazic acids. Overall, these results demonstrate the feasibility of cell-free translation for peptide NP total synthesis while expanding the limits of the technology. This work provides a novel computational tool for exploration of peptide NP chemical space, that could be expanded in the future to allow design of ribosomal biosynthetic pathways for NPs and NP-like molecules.
The COVID-19 pandemic has had a significant impact beyond physical morbidity and mortality. A mid-cycle Community Health Needs Assessment survey was administered in 1 community to generate data to ...evaluate change in community well-being since the beginning of the pandemic.
Surveys were mailed to 2,000 randomly selected residents in Olmsetd County, Minnesota. The surveys included the WHO Well-being Index (previously included in the 2018 Community Health Needs Assessment) and new subjective questions regarding behavior change. Changes in well-being were calculated using a propensity-matched cohort, and behavior change was reported as proportions of the whole. Data analysis was completed in 2021.
Total survey respondents were 569 people in 2018 and 723 people in 2021. Well-being scores from the WHO Well-being Index showed a statistically significant decrease (score reduction of −8.44) from 2018 to 2021. All the 5 questions from the WHO Well-being Index also had an individual significant decrease; with the question regarding interest in life showing the greatest decrease. Individuals reported decreased subjective physical and mental well-being and increased substance use (alcohol, marijuana, and tobacco). Households also reported decreased household incomes and worse household finances since the start of the pandemic.
Using the Community Health Needs Assessment infrastructure, 1 community was able to compare prepandemic with postpandemic data, which showed decreased well-being and increased substance use and financial stress. Other public health planners can similarly conduct interval surveys on the basis of their Community Health Needs Assessment questionnaires to tailor ongoing Community Health Improvement Plan programming to postpandemic needs and track community mental health and well-being recovery.
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