Search results for "Dynamic"
showing 10 items of 12329 documents
Extraordinary tuning of a nanocavity by a near-field probe
2011
Abstract We report here an experimental observation of an extraordinary near-field interaction between a local probe and a small-volume solid-state nanocavity. We directly compare the normally observed near-field interaction regime driven by the perturbation theory and then report the extraordinary interaction regime. Subsequently, we show that the cavity can take up to 2 min to recover from this interaction after removing the probe and that leads to an extraordinary blue-shift of the cavity resonance wavelength (∼15 nm) which depends on the probe motion above the cavity and not the position. The reasons for this effect are not fully understood yet but we try to give some explanations.
An environment based approach for the ant colony convergence
2020
Abstract Ant colony optimization (ACO) algorithms are a bio inspired solutions which have been very successful in combinatorial problem solving, also known as NP-hard problems, including transportation system optimization. As opposed to exact methods, which could give the best results of a tested problem, this meta-heuristics is based on the stochastic logic but not on theoretical mathematics demonstration (or only on certain well defined applications). According to this, the weak point of this meta-heuristics is his convergence, its termination condition. We can finds many different termination criteria in the scientific literature, yet most of them are costly in resources and unsuitable f…
Fragmentation of anthracene C14H10, acridine C13H9N and phenazine C12H8N2 ions in collisions with atoms
2014
International audience; We report experimental total, absolute, fragmentation cross sections for anthracene C14H10, acridine C13H9N, and phenazine C12H8N2 ions colliding with He at center-of-mass energies close to 100 eV. In addition, we report results for the same ions colliding with Ne, Ar, and Xe at higher energies. The total fragmentation cross sections for these three ions are the same within error bars for a given target. The measured fragment mass distributions reveal significant contributions from both delayed (≫10−12 s) statistical fragmentation processes as well as non-statistical, prompt (∼10−15 s), single atom knockout processes. The latter dominate and are often followed by sec…
QSAR Modeling ANTI-HIV-1 Activities by Optimization of Correlation Weights of Local Graph Invariants
2004
Results of using descriptors calculated with the correlation weights (CWs) of local graph invariants for modeling of anti-HIV-1 potencies of two groups of reverse transcriptase (RT) inhibitors are reported. Presence of different chemical elements in molecular structure of the inhibitors and the presence of Morgan extended connectivity values of zeroth-, first- and second order have been examined as local graph invariants in the labeled hydrogen-filled graphs. By Monte Carlo method optimization procedure, values of the CWs which produce as large values as possible of correlation coefficient between the numerical data on the anti-HIV-1 potencies and values of the descriptors on the training s…
Characterization of the interaction of the antifungal and cytotoxic cyclic glycolipopeptide hassallidin with sterol-containing lipid membranes.
2019
Hassallidins are cyclic glycolipopeptides produced by cyanobacteria and other prokaryotes. The hassallidin structure consists of a peptide ring of eight amino acids where a fatty acid chain, additional amino acids, and sugar moieties are attached. Hassallidins show antifungal activity against several opportunistic human pathogenic fungi, but does not harbor antibacterial effects. However, they have not been studied on mammalian cells, and the mechanism of action is unknown. We purified hassallidin D from cultured cyanobacterium Anabaena sp. UHCC 0258 and characterized its effect on mammalian and fungal cells. Ultrastructural analysis showed that hassallidin D disrupts cell membranes, causin…
Correlation spectroscopy in molten and supercooled antimony trichloride.
1990
Correlation spectroscopy measurements performed on molten and supercooled antimony trichloride with the homodyne technique show correlation functions that have a nonexponential behavior. Two well-defined distributions of correlation times can be observed in different temporal regions. This behavior is discussed in terms of a structural relaxation of clusters dynamically formed by intermolecular and interchain bonds. The Arrhenius plot of these correlation times shows a linear behavior with the same activation energy for both. In contrast, the activation energy of shear viscosity has a different value, showing that the processes determining the temperature behavior of \ensuremath{\tau} and $…
Thermodynamic and19F NMR studies of antimony trifluoride in water
1993
Densities, specific heat capacities per unit volume and enthalpies of dilution at 25°C and osmotic coefficients at 37°C were measured for antimony trifluoride in water as functions of concentration. From the first three properties the apparent and partial molar volumes, heat capacities and relative enthalpies were derived. As well, pH measurements in water at 25°C and19F NMR spectra in water and methanol at 33°C were also carried out. All the thermodynamic properties together with the chemical shifts abruptly change in the very dilute concentration region (<0.1m) and, then, tend to a constant value. These trends have been rationalized through a simple model based on an equilibrium of dissoc…
Recent advances in computational design of potent aromatase inhibitors: open-eye on endocrine-resistant breast cancers.
2019
Introduction: The vast majority of breast cancers (BC) are estrogen receptor positive (ER+). The most effective treatments to fight this BC type rely on estrogen deprivation therapy, by inhibiting the aromatase enzyme, which performs estrogen biosynthesis, or on blocking the estrogens signaling path via modulating/degrading the estrogen's specific nuclear receptor (estrogen receptor-?, ER?). While being effective at early disease stage, patients treated with aromatase inhibitors (AIs) may acquire resistance and often relapse after prolonged therapies. Areas covered: In this compendium, after an overview of the historical development of the AIs currently in clinical use, and of the computati…
Ant Abundance along a Productivity Gradient: Addressing Two Conflicting Hypotheses
2015
The number of individuals within a population or community and their body size can be associated with changes in resource supply. While these relationships may provide a key to better understand the role of abiotic vs. biotic constraints in animal communities, little is known about the way size and abundance of organisms change along resource gradients. Here, we studied this interplay in ants, addressing two hypotheses with opposite predictions regarding variation in population densities along resource gradients- the 'productivity hypothesis' and the 'productivity-based thinning hypothesis'. The hypotheses were tested in two functional groups of ground-dwelling ants that are directly primar…
Psychopathological and psychodynamic hypotheses for pediatric stuttering
2018
Stuttering is a common language alteration in pediatric age consisting in repetitions and blocks, which entail a break in the rhythm and melody of the speech. According to the WHO it is a disorder of the rhythm of the word, the subject knows precisely what he would like to say, but at the same time he is not able to say it. It is a great inconvenience for those affected, also because the slowing down of speaking is not about thought or cognitive skills.