scholarly journals Dynamic simulations of many-body electrostatic self-assembly

2018 ◽  
Vol 376 (2115) ◽  
pp. 20170143 ◽  
Author(s):  
Eric B. Lindgren ◽  
Benjamin Stamm ◽  
Yvon Maday ◽  
Elena Besley ◽  
A. J. Stace
Keyword(s):  
Self Assembly ◽  
Experimental Studies ◽  
Charged Particles ◽  
Theoretical Chemistry ◽  
Many Body ◽  
Single Particles ◽  
Theme Issue ◽  
Dynamic Simulations ◽  
The Subject ◽  
Small Clusters

Two experimental studies relating to electrostatic self-assembly have been the subject of dynamic computer simulations, where the consequences of changing the charge and the dielectric constant of the materials concerned have been explored. One series of calculations relates to experiments on the assembly of polymer particles that have been subjected to tribocharging and the simulations successfully reproduce many of the observed patterns of behaviour. A second study explores events observed following collisions between single particles and small clusters composed of charged particles derived from a metal oxide composite. As before, observations recorded during the course of the experiments are reproduced by the calculations. One study in particular reveals how particle polarizability can influence the assembly process. This article is part of the theme issue ‘Modern theoretical chemistry’.

scholarly journals Vocal production learning in mammals revisited

2021 ◽  
Vol 376 (1836) ◽  
pp. 20200244
Author(s):  
Vincent M. Janik ◽  
Mirjam Knörnschild
Keyword(s):  
Experimental Studies ◽  
Vocal Learning ◽  
Type Result ◽  
Theme Issue ◽  
Vocal Production ◽  
Learning Skills ◽  
Acoustic Models ◽  
Vocal Convergence ◽  
The Subject ◽  
Underlying Mechanisms

Vocal production learning, the ability to modify the structure of vocalizations as a result of hearing those of others, has been studied extensively in birds but less attention has been given to its occurrence in mammals. We summarize the available evidence for vocal learning in mammals from the last 25 years, updating earlier reviews on the subject. The clearest evidence comes from cetaceans, pinnipeds, elephants and bats where species have been found to copy artificial or human language sounds, or match acoustic models of different sound types. Vocal convergence, in which parameter adjustments within one sound type result in similarities between individuals, occurs in a wider range of mammalian orders with additional evidence from primates, mole-rats, goats and mice. Currently, the underlying mechanisms for convergence are unclear with vocal production learning but also usage learning or matching physiological states being possible explanations. For experimental studies, we highlight the importance of quantitative comparisons of seemingly learned sounds with vocal repertoires before learning started or with species repertoires to confirm novelty. Further studies on the mammalian orders presented here as well as others are needed to explore learning skills and limitations in greater detail. This article is part of the theme issue ‘Vocal learning in animals and humans’.

scholarly journals Cooking up the perfect insect: Aristotle's transformational idea about the complete metamorphosis of insects

2019 ◽  
Vol 374 (1783) ◽  
pp. 20190074 ◽  
Author(s):  
Stuart Reynolds
Keyword(s):  
Seventeenth Century ◽  
Self Assembly ◽  
Female Parent ◽  
Spontaneous Generation ◽  
Theme Issue ◽  
Larval Stages ◽  
Complete State ◽  
The Subject ◽  
Complete Metamorphosis ◽  
Frequent Reference

Aristotle made important contributions to the study of developmental biology, including the complete metamorphosis of insects. One concept in particular, that of the perfect or complete state, underlies Aristotle's ideas about metamorphosis, the necessity of fertilization for embryonic development, and whether morphogenesis involves an autonomous process of self-assembly. Importantly, the philosopher erroneously views metamorphosis as a necessary developmental response to lack of previous fertilization of the female parent, a view that is intimately connected with his readiness to accept the idea of the spontaneous generation of life. Aristotle's work underpins that of the major seventeenth century students of metamorphosis, Harvey, Redi, Malpighi and Swammerdam, all of whom make frequent reference to Aristotle in their writings. Although both Aristotle and Harvey are often credited with inspiring the later prolonged debate between proponents of epigenesis and preformation, neither actually held firm views on the subject. Aristotle's idea of the perfect stage also underlies his proposal that the eggs of holometabolous insects hatch ‘before their time’, an idea that is the direct precursor of the much later proposals by Lubbock and Berlese that the larval stages of holometabolous insects are due to the ‘premature hatching’ from the egg of an imperfect embryonic stage. This article is part of the theme issue ‘The evolution of complete metamorphosis’.

Data-Driven Many-Body Models with Chemical Accuracy for CH4/H2O Mixtures

2020 ◽  
Author(s):  
Marc Riera ◽  
Alan Hirales ◽  
Raja Ghosh ◽  
Francesco Paesani
Keyword(s):  
Liquid Phase ◽  
Quantitative Description ◽  
Liquid Mixtures ◽  
Many Body ◽  
Energy Functions ◽  
Potential Energy Functions ◽  
Dynamics Simulations ◽  
Body Potential ◽  
Small Clusters ◽  
Many Body Interactions

<div> <div> <div> <p>Many-body potential energy functions (PEFs) based on the TTM-nrg and MB-nrg theoretical/computational frameworks are developed from coupled cluster reference data for neat methane and mixed methane/water systems. It is shown that that the MB-nrg PEFs achieve subchemical accuracy in the representation of individual many-body effects in small clusters and enables predictive simulations from the gas to the liquid phase. Analysis of structural properties calculated from molecular dynamics simulations of liquid methane and methane/water mixtures using both TTM-nrg and MB-nrg PEFs indicates that, while accounting for polarization effects is important for a correct description of many-body interactions in the liquid phase, an accurate representation of short-range interactions, as provided by the MB-nrg PEFs, is necessary for a quantitative description of the local solvation structure in liquid mixtures. </p> </div> </div> </div>

Evaporative self-assembly of binary mixture of soft colloids

2021 ◽  
Author(s):  
Merin Jose ◽  
Muraleedharapai Mayarani ◽  
Madivala G Basavaraj ◽  
Dillip Kumar Satapathy
Keyword(s):  
Binary Mixture ◽  
Self Assembly ◽  
Sessile Drop ◽  
Experimental Studies ◽  
The Self ◽  
Soft Colloids

We report experimental studies on the self-assembly and degree of ordering of binary mixture of soft colloids in the monolayer deposits obtained by controlled evaporation. A sessile drop containing soft...

scholarly journals Extracting Hypernuclear Properties from the (e, e′K+) Cross Section

Particles ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 194-204
Author(s):  
Omar Benhar
Keyword(s):  
Cross Section ◽  
Experimental Studies ◽  
Strong Interactions ◽  
Many Body ◽  
Kaon Production ◽  
Many Body Theory ◽  
Independent Analysis ◽  
Dense Nuclear Matter ◽  
Proton Knockout ◽  
Comprehensive Framework

Experimental studies of hypernuclear dynamics, besides being essential for the understanding of strong interactions in the strange sector, have important astrophysical implications. The observation of neutron stars with masses exceeding two solar masses poses a serious challenge to the models of hyperon dynamics in dense nuclear matter, many of which predict a maximum mass incompatible with the data. In this paper, it is argued that valuable new insight can be gained from the forthcoming extension of the experimental studies of kaon electro production from nuclei to include the 208Pb(e,e′K+)Λ208Tl process. A comprehensive framework for the description of kaon electro production, based on factorization of the nuclear cross section and the formalism of the nuclear many-body theory, is outlined. This approach highlights the connection between the kaon production and proton knockout reactions, which will allow us to exploit the available 208Pb(e,e′p)207Tl data to achieve a largely model-independent analysis of the measured cross section.

scholarly journals The Non-Relativistic Many-Body Quantum-Mechanical Hamiltonian with Diamagnetic Current-Current Interaction

2021 ◽  
Author(s):  
Ladislaus Alexander Bányai
Keyword(s):  
Solid State ◽  
Analogous Result ◽  
Charged Particles ◽  
Coulomb Gauge ◽  
Quantum Mechanical ◽  
Photon Propagator ◽  
Coulomb Interactions ◽  
Many Body ◽  
Transverse Current ◽  
Current Interaction

AbstractWe extend the standard solid-state quantum mechanical Hamiltonian containing only Coulomb interactions between the charged particles by inclusion of the (transverse) current-current diamagnetic interaction starting from the non-relativistic QED restricted to the states without photons and neglecting the retardation in the photon propagator. This derivation is supplemented with a derivation of an analogous result along the non-rigorous old classical Darwin-Landau-Lifshitz argumentation within the physical Coulomb gauge.

Oliver Heaviside: an accidental time traveller

2018 ◽  
Vol 376 (2134) ◽  
pp. 20170448
Author(s):  
Paul J. Nahin
Keyword(s):  
Cherenkov Radiation ◽  
Charged Particles ◽  
Electromagnetic Theory ◽  
Time Travel ◽  
Characteristic Radiation ◽  
Theme Issue ◽  
The Past ◽  
Faster Than Light

A little discussed aspect of Heaviside's work in electromagnetics concerned faster-than-light (FTL) charged particles, precursors to the hypothetical tachyon and his discovery that such motion should produce a characteristic radiation signature (now called Cherenkov radiation ). When Heaviside wrote, the time travel implications of FTL were not known (Einstein was still a teenager), and in this paper some speculations are offered on what Heaviside would have thought of FTL time travel, and of the associated (now classic) time travel paradoxes, including the possibility (or not) of sending information into the past. This article is part of the theme issue ‘Celebrating 125 years of Oliver Heaviside's ‘Electromagnetic Theory’’.

scholarly journals The macroscopic shape of assemblies formed from microparticles based on host–guest interaction dependent on the guest content

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Takahiro Itami ◽  
Akihito Hashidzume ◽  
Yuri Kamon ◽  
Hiroyasu Yamaguchi ◽  
Akira Harada
Keyword(s):  
Molecular Recognition ◽  
Smart Materials ◽  
Self Assembly ◽  
Early Stage ◽  
Contact Point ◽  
Sodium Acrylate ◽  
Contact Points ◽  
Assembly Behavior ◽  
Small Clusters ◽  
Macroscopic Shape

AbstractBiological macroscopic assemblies have inspired researchers to utilize molecular recognition to develop smart materials in these decades. Recently, macroscopic self-assemblies based on molecular recognition have been realized using millimeter-scale hydrogel pieces possessing molecular recognition moieties. During the study on macroscopic self-assembly based on molecular recognition, we noticed that the shape of assemblies might be dependent on the host–guest pair. In this study, we were thus motivated to study the macroscopic shape of assemblies formed through host–guest interaction. We modified crosslinked poly(sodium acrylate) microparticles, i.e., superabsorbent polymer (SAP) microparticles, with β-cyclodextrin (βCD) and adamantyl (Ad) residues (βCD(x)-SAP and Ad(y)-SAP microparticles, respectively, where x and y denote the mol% contents of βCD and Ad residues). Then, we studied the self-assembly behavior of βCD(x)-SAP and Ad(y)-SAP microparticles through the complexation of βCD with Ad residues. There was a threshold of the βCD content in βCD(x)-SAP microparticles for assembly formation between x = 22.3 and 26.7. On the other hand, the shape of assemblies was dependent on the Ad content, y; More elongated assemblies were formed at a higher y. This may be because, at a higher y, small clusters formed in an early stage can stick together even upon collisions at a single contact point to form elongated aggregates, whereas, at a smaller y, small clusters stick together only upon collisions at multiple contact points to give rather circular assemblies. On the basis of these observations, the shape of assembly formed from microparticles can be controlled by varying y.

THE INFLUENCE OF AGE ON PERFORMANCE AS SHOWN BY EXERCISE TESTS

PEDIATRICS ◽  
1963 ◽  
Vol 32 (4) ◽  
pp. 737-741
Author(s):  
D. B. Dill
Keyword(s):  
Work Performance ◽  
Experimental Studies ◽  
Business Administration ◽  
Distance Runner ◽  
Indiana University ◽  
Exercise Tests ◽  
The Subject ◽  
To Come ◽  
The Many ◽  
Harvard School

THE STUDY of work performance as related to age began in this country when Sid Robinson joined the group at the Fatigue Laboratory of the Harvard School of Business Administration. In the winter of 1936-7, he persuaded five champion milers who were in Boston for indoor meets to run on the Laboratory's treadmill on week-ends. Simultaneously, he was chiefly engaged in studying treadmill performance as related to age. This was the subject of his doctorate thesis published later under the title: "Experimental Studies of Physical Fitness as Related to Age". The 91 subjects ranged in age from boys 6 years of age to one man of 91. There were eight 6-year-olds, 10 between 8 and 13 and 20 between 48 and 76. Robinson's background as an Olympic middle-distance runner and as an assistant track coach at Indiana University gave him skill in dealing with the many diverse problems that confronted him. Often he was faced with sociological-psychological problems more difficult to solve than the physiological problems. Indicative of his success is the fact that the subjects were volunteers—no money was offered as an inducement to come to the laboratory. Also worthy of note is that there was no untoward incident throughout the study. Robinson's plan included respiratory, circulatory and metabolic observations in the basal state and in two grades of exercise. He describes the work experiments as follows: (pp. 251-3, reference 2) "After the above observations were completed, the subject performed two grades of work on a motor-driven treadmill, set at an angle of 8.6% in all experiments. Each subject below 73 years of age first walked at 5.6 km per hour for 15 minutes; this raises the oxygen consumption 7 or 8 times the basal level. After resting 10 minutes, he ran or in some cases, walked, at a rate which exhausted him in 2 to 5 minutes.

Analysis of Collective Resonances in Clusters: Metals and Carbon

1992 ◽  
Vol 272 ◽  
Author(s):  
Vitaly V. Kresin
Keyword(s):  
Random Phase Approximation ◽  
Sum Rules ◽  
Random Phase ◽  
Closed Shell ◽  
Dynamical Response ◽  
Many Body ◽  
Resonance Frequencies ◽  
Unified View ◽  
Small Clusters ◽  
Good Agreement

ABSTRACTDipole photoabsorption spectra of small clusters are analyzed. Two types of systems are considered: metal clusters and the carbon fullerenes. Both have been found to exhibit strong collective photoabsorption modes associated with the motion of delocalized electrons. We describe analytical results for the resonance frequencies in both spherical (closed-shell metallic, C60 ) and spheroidal (openshell metallic, C70) particles. The calculation is based on the techniques of many-body physics (random-phase approximation, sum rules), affords a unified view of the dynamical response of microscopic clusters, and leads to good agreement with experimental data.

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