Search results for "Dynamic"
showing 10 items of 12329 documents
Longitudinal metagenomics
2018
Culture-independent approaches are revolutionizing biology. Whether in a clinical or in an environmental sample, metagenomics can reveal which microorganisms exist and what they actually do. Metagenomic studies have unveiled more microbial diversity in a few years than traditional microbiology in centuries. From the top branches down to the roots, its discoveries are reshaping the tree of life dramatically. Metagenomics is a powerful tool for the study of microbial communities, but it requires equally powerful methods of analysis. Current challenges in the analysis of metagenomic data include the accurate comparison of samples, the estimation of the uncertainty in the results, and the effec…
CH vs. HC—Promiscuous Metal Sponges in Antimicrobial Peptides and Metallophores
2023
Histidine and cysteine residues, with their imidazole and thiol moieties that deprotonate at approximately physiological pH values, are primary binding sites for Zn(II), Ni(II) and Fe(II) ions and are thus ubiquitous both in peptidic metallophores and in antimicrobial peptides that may use nutritional immunity as a way to limit pathogenicity during infection. We focus on metal complex solution equilibria of model sequences encompassing Cys–His and His–Cys motifs, showing that the position of histidine and cysteine residues in the sequence has a crucial impact on its coordination properties. CH and HC motifs occur as many as 411 times in the antimicrobial peptide database, while …
NONEQUILIBRIUM PHENOMENA AND METASTABILITY IN MESOSCOPIC AND QUANTUM SYSTEMS
2020
Here we summarize some relevant results related to nonequilibrium phenomena in mesoscopic and quantum systems. A common phenomenon in the dynamics of out-of-equilibrium systems is the metastability, and the problem of the lifetime of metastable states involves fundamental aspects of nonequilibrium statistical mechanics. Metastability (see Fig. 1) is a signature of a first order phase transition, often characterized by a long-living metastable state. In particular, the stability of a metastable state can be enhanced by Gaussian and non-Gaussian noise sources. This counterintuitive effect has been found in different physical areas, ranging from spintronics, aggregation kinetics of Brownian pa…
Dielectric properties of myoglobin at 10 GHz by microwave cavity perturbation measurements
2010
We report on the temperature dependence, at microwave (mw) frequency, of the imaginary part of the dielectric constant (En) in myoglobin powder samples with different hydration levels (h). The measurements have been performed by the cavity perturbation technique, in the range of temperature 80-345 K. The sample is located inside a glass capillary along the axis of a cylindrical copper cavity, resonating in the TE011 mode at 9.6 GHz, where the mw electric field has a node. By measuring the variation of the quality factor of the resonant cavity, one can extract the imaginary part of the dielectric constant. At temperatures higher than 230 K we observe an evident increase of the dielectric los…
Investigation on the stability of dispersion of zirconia nanoparticles prepared by microwave- hydrothermal synthesis
2005
Difficulties in reproducing the performances of nanoparticles dispersions are obstructive for the progress of the nanotechnology. A plausible reason for this variability is the lack of the control of the stability as well as the dimensions of the nanoparticles in the dispersions. In this work we report results of investigations on the stability of zirconia nanoparticles in aqueous medium, monitoring nanoparticles sizes by means of Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS). Nanocrystalline zirconia powders, prepared by microwave-hydrothermal synthesis, were determined to be 6-8 nm in size by TEM observations. By using DLS technique the as-prepared dispersions wit…
Patterns of word reading skill, interest and self-concept of ability
2016
AbstractThe majority of previous research on academic skills, self-concept of ability and interest has deployed the variable-oriented approach and focused on self-concept, or ability, or interest only. This study examined the patterns and dynamics of pattern change in Finnish children’s word reading skill, self-concept of ability and interest from kindergarten to Grade 2. Six groups of children were identified by using the I-states as objects analysis (ISOA) procedure: (a) low skills, negative self-concept but high interest; (b) high skills but low interest; (c) average; (d) high skills, positive self-concept and high interest; (e) low skills, negative self-concept and low interest; and (f)…
An EEMD Aided Comparison of Time Histories and Its Application in Vehicle Safety
2017
In the context of signal processing, the comparison of time histories is required for different purposes, especially for the model validation of vehicle safety. Most of the existing metrics focus on the mathematical value only. Therefore, they suffer the measuring errors, disturbance, and uncertainties and can hardly achieve a stable result with a clear physical interpretation. This paper proposes a novel scheme of time histories comparison to be used in vehicle safety analysis. More specifically, each signal for comparison is decomposed into a trend signal and several intrinsic mode functions (IMFs) by ensemble empirical mode decomposition. The trend signals reflect the general variation a…
Modelling Dynamic Systems: Examples Involving an Iconic Oriented Environment
2005
We present a modelling environment based on the use of iconic representations consisting of elements, as containers and connected flows, able to describe the relationships between relevant variables of dynamic systems. The procedures involved are aimed to make students aware of the reasoning processes to describe, formalise and explain complex system behaviours. Moreover, we show how these strategies may allow the overcoming of some well-known difficulties involved in pupil understanding of mathematical formalisms, such as derivatives and differential equations and their real meaning. Our reported modelling examples were experimented on during some laboratory sessions of the Pre-Service Sch…
Recursion at the crossroads of sequence modeling, random trees, stochastic algorithms and martingales
2013
This monograph synthesizes several studies spanning from dynamical systems in the statistical analysis of sequences, to analysis of algorithms in random trees and discrete stochastic processes. These works find applications in various fields ranging from biological sequences to linear regression models, branching processes, through functional statistics and estimates of risk indicators for insurances. All the established results use, in one way or another, the recursive property of the structure under study, by highlighting invariants such as martingales, which are at the heart of this monograph, as tools as well as objects of study.