scholarly journals Thermally active nanoparticle clusters enslaved by engineered domain wall traps

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pietro Tierno ◽  
Tom H. Johansen ◽  
Arthur V. Straube
Keyword(s):  
Two Dimensions ◽  
Stray Field ◽  
Magnetic Traps ◽  
Pairwise Interactions ◽  
Ferromagnetic Domains ◽  
Nanoparticle Clusters ◽  
Dynamical Regimes ◽  
Model Platform ◽  
Repulsive Forces ◽  
Tunable Stiffness

AbstractThe stable assembly of fluctuating nanoparticle clusters on a surface represents a technological challenge of widespread interest for both fundamental and applied research. Here we demonstrate a technique to stably confine in two dimensions clusters of interacting nanoparticles via size-tunable, virtual magnetic traps. We use cylindrical Bloch walls arranged to form a triangular lattice of ferromagnetic domains within an epitaxially grown ferrite garnet film. At each domain, the magnetic stray field generates an effective harmonic potential with a field tunable stiffness. The experiments are combined with theory to show that the magnetic confinement is effectively harmonic and pairwise interactions are of dipolar nature, leading to central, strictly repulsive forces. For clusters of magnetic nanoparticles, the stationary collective states arise from the competition between repulsion, confinement and the tendency to fill the central potential well. Using a numerical simulation model as a quantitative map between the experiments and theory we explore the field-induced crystallization process for larger clusters and unveil the existence of three different dynamical regimes. The present method provides a model platform for investigations of the collective phenomena emerging when strongly confined nanoparticle clusters are forced to move in an idealized, harmonic-like potential.

scholarly journals Thermally active nanoparticle clusters enslaved by engineered domain wall traps

2021 ◽  
Author(s):  
Pietro Tierno ◽  
Tom Johansen ◽  
Arthur Straube
Keyword(s):  
Two Dimensions ◽  
Stray Field ◽  
Magnetic Traps ◽  
Pairwise Interactions ◽  
Ferromagnetic Domains ◽  
Nanoparticle Clusters ◽  
Dynamical Regimes ◽  
Model Platform ◽  
Repulsive Forces ◽  
Tunable Stiffness

Abstract The stable assembly of fluctuating nanoparticle clusters on a surface represents a technological challenge of widespread interest for both fundamental and applied research. Here we demonstrate a technique to stably confine in two dimensions clusters of interacting nanoparticles via size-tunable, virtual magnetic traps. We use cylindrical Bloch walls arranged to form a triangular lattice of ferromagnetic domains within an epitaxially grown ferrite garnet film. At each domain, the magnetic stray field generates an effective harmonic potential with a field tunable stiffness. The experiments are combined with theory to show that the magnetic confinement is effectively harmonic and pairwise interactions are of dipolar nature, leading to central, strictly repulsive forces. For clusters of magnetic nanoparticles, the stationary collective states arise from the competition between repulsion, confinement as the tendency to fill the central potential well. Using a numerical simulation model as a quantitative map between the experiment and theory we explore the field-induced crystallization process for larger clusters and unveil the existence of three different dynamical regimes. The present method provides a model platform for investigations of the collective phenomena emerging when strongly confined nanoparticle clusters are forced to move in an idealized, harmonic-like potential.

Electron Acceleration in Collapsing Magnetic Traps during the Solar Flare on July 19, 2012: Observations and Models

2017 ◽  
Vol 13 (S335) ◽  
pp. 90-93
Author(s):  
P. A. Gritsyk ◽  
B. V. Somov
Keyword(s):  
Point Source ◽  
Solar Flares ◽  
High Efficiency ◽  
Reverse Current ◽  
Electron Acceleration ◽  
Thick Target ◽  
Two Dimensions ◽  
Magnetic Traps ◽  
Thin Target ◽  
X Ray

AbstractUsing the appropriate kinetic equation, we considered the problem of propagation of accelerated electrons into the solar corona and chromosphere. Its analytical solution was used for modelling the M7.7 class limb flare occurred on July 19, 2012. Coronal above-the-loop-top hard X-Ray source was interpreted in the thin-target approximation, the foot-point source - in the thick-target approximation with account of the reverse-current electric field. For the foot-point source we found a good accordance with the RHESSI observations. For the coronal source we also got very accurate estimate of the power-law spectral index, but significant differences between the modelled and observed hard X-ray intensities were noticed. The last discrepancy was solved by adding the coronal magnetic trap model to the thin target model. The former one implies that the trap collapses in two dimensions, locks and accelerates particles inside itself. In our report, we confirm an existence and high efficiency of the electron acceleration in collapsing magnetic traps during solar flares. Our new results represent (e.g. for RHESSI observations) the theoretical prediction of the double step particle acceleration in solar flares, when the first step is the acceleration in reconnection area and the second one – the acceleration in coronal trap.

The tangled web of agency

2018 ◽  
Vol 41 ◽  
Author(s):  
Alain Pe-Curto ◽  
Julien A. Deonna ◽  
David Sander
Keyword(s):  
Two Dimensions ◽  
Bad Company

AbstractWe characterize Doris's anti-reflectivist, collaborativist, valuational theory along two dimensions. The first dimension is socialentanglement, according to which cognition, agency, and selves are socially embedded. The second dimension isdisentanglement, the valuational element of the theory that licenses the anchoring of agency and responsibility in distinct actors. We then present an issue for the account: theproblem of bad company.

A transmission electron microscopic study of structural transitions in fast ionic conductors

1987 ◽  
Vol 45 ◽  
pp. 156-157
Author(s):  
R. B. Queenan ◽  
P. K. Davies
Keyword(s):  
Optical Properties ◽  
Ionic Conduction ◽  
Recent Observation ◽  
Ionic Conductivities ◽  
Sodium Aluminate ◽  
Two Dimensions ◽  
Ionic Conductors ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Trivalent Cations

Na ß“-alumina (Na1.67Mg67Al10.33O17) is a non-stoichiometric sodium aluminate which exhibits fast ionic conduction of the Na+ ions in two dimensions. The Na+ ions can be exchanged with a variety of mono-, di-, and trivalent cations. The resulting exchanged materials also show high ionic conductivities.Considerable interest in the Na+-Nd3+-ß“-aluminas has been generated as a result of the recent observation of lasing in the pulsed and cw modes. A recent TEM investigation on a 100% exchanged Nd ß“-alumina sample found evidence for the intergrowth of two different structure types. Microdiffraction revealed an ordered phase coexisting with an apparently disordered phase, in which the cations are completely randomized in two dimensions. If an order-disorder transition is present then the cooling rates would be expected to affect the microstructures of these materials which may in turn affect the optical properties. The purpose of this work was to investigate the affect of thermal treatments upon the micro-structural and optical properties of these materials.

Laser Scanning Confocal Microscopy and Three-Dimesnsional Reconstruction of the Mitotic Spindles of Unequally Dividing Embryonic Cells

1990 ◽  
Vol 48 (3) ◽  
pp. 166-167
Author(s):  
J. Holy ◽  
G. Schatten
Keyword(s):  
Confocal Microscopy ◽  
Mitotic Spindle ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Confocal Microscopy ◽  
Two Dimensions ◽  
Embryonic Cells ◽  
Mitotic Spindles ◽  
Cleavage Division ◽  
Scanning Confocal Microscopy

One of the classic limitations of light microscopy has been the fact that three dimensional biological events could only be visualized in two dimensions. Recently, this shortcoming has been overcome by combining the technologies of laser scanning confocal microscopy (LSCM) and computer processing of microscopical data by volume rendering methods. We have employed these techniques to examine morphogenetic events characterizing early development of sea urchin embryos. Specifically, the fourth cleavage division was examined because it is at this point that the first morphological signs of cell differentiation appear, manifested in the production of macromeres and micromeres by unequally dividing vegetal blastomeres.The mitotic spindle within vegetal blastomeres undergoing unequal cleavage are highly polarized and develop specialized, flattened asters toward the micromere pole. In order to reconstruct the three-dimensional features of these spindles, both isolated spindles and intact, extracted embryos were fluorescently labeled with antibodies directed against either centrosomes or tubulin.

Instrumental and Ideological Union Commitment: Longitudinal Assessment of Construct Validity

2001 ◽  
Vol 17 (2) ◽  
pp. 98-111 ◽  
Author(s):  
Anders Sjöberg ◽  
Magnus Sverke
Keyword(s):  
Construct Validity ◽  
Temporal Stability ◽  
Strong Support ◽  
Internal Consistency Reliability ◽  
Measurement Model ◽  
Two Dimensions ◽  
Model Parameters ◽  
Longitudinal Assessment ◽  
Union Commitment ◽  
Union Participation

Summary: Previous research has identified instrumentality and ideology as important aspects of member attachment to labor unions. The present study evaluated the construct validity of a scale designed to reflect the two dimensions of instrumental and ideological union commitment using a sample of 1170 Swedish blue-collar union members. Longitudinal data were used to test seven propositions referring to the dimensionality, internal consistency reliability, and temporal stability of the scale as well as postulated group differences in union participation to which the scale should be sensitive. Support for the hypothesized factor structure of the scale and for adequate reliabilities of the dimensions was obtained and was also replicated 18 months later. Tests for equality of measurement model parameters and test-retest correlations indicated support for the temporal stability of the scale. In addition, the results were consistent with most of the predicted differences between groups characterized by different patterns of change/stability in union participation status. The study provides strong support for the construct validity of the scale and indicates that it can be used in future theory testing on instrumental and ideological union commitment.

The Prediction of Problem-Solving Assessed Via Microworlds

2016 ◽  
Vol 32 (4) ◽  
pp. 298-306 ◽  
Author(s):  
Samuel Greiff ◽  
Katarina Krkovic ◽  
Jarkko Hautamäki
Keyword(s):  
Working Memory ◽  
Problem Solving ◽  
Complex Problem ◽  
Two Dimensions ◽  
Assessment Instruments ◽  
Complex Problem Solving ◽  
Visual Spatial ◽  
Rule Knowledge ◽  
Rule Application ◽  
Fluid Reasoning

Abstract. In this study, we explored the network of relations between fluid reasoning, working memory, and the two dimensions of complex problem solving, rule knowledge and rule application. In doing so, we replicated the recent study by Bühner, Kröner, and Ziegler (2008) and the structural relations investigated therein [ Bühner, Kröner, & Ziegler, (2008) . Working memory, visual-spatial intelligence and their relationship to problem-solving. Intelligence, 36, 672–680]. However, in the present study, we used different assessment instruments by employing assessments of figural, numerical, and verbal fluid reasoning, an assessment of numerical working memory, and a complex problem solving assessment using the MicroDYN approach. In a sample of N = 2,029 Finnish sixth-grade students of which 328 students took the numerical working memory assessment, the findings diverged substantially from the results reported by Bühner et al. Importantly, in the present study, fluid reasoning was the main source of variation for rule knowledge and rule application, and working memory contributed only a little added value. Albeit generally in line with previously conducted research on the relation between complex problem solving and other cognitive abilities, these findings directly contrast the results of Bühner et al. (2008) who reported that only working memory was a source of variation in complex problem solving, whereas fluid reasoning was not. Explanations for the different patterns of results are sought, and implications for the use of assessment instruments and for research on interindividual differences in complex problem solving are discussed.

Development of the Fear of Intimacy Components Questionnaire (FICQ)

2015 ◽  
Vol 31 (4) ◽  
pp. 302-309 ◽  
Author(s):  
Maria Pedro Sobral ◽  
Maria Emília Costa
Keyword(s):  
Convergent Validity ◽  
Discriminant Validity ◽  
Two Dimensions ◽  
Dimensional Structure ◽  
Future Research ◽  
Fear Of Intimacy ◽  
Confirmatory Factor Analyses ◽  
New Instrument ◽  
Confirmatory Factor ◽  
Test Retest Reliability

Abstract. We developed a new instrument designed to measure fear of intimacy in romantic relationships. We suggest assessing fear of intimacy through two dimensions: self-revelation and dependence. The Fear of Intimacy Components Questionnaire (FICQ) was validated across three studies in which a 10-item solution systematically emerged. Consistently with a two component perspective, a two-factor solution fitted data the best: fear of losing the self (FLS) and fear of losing the other (FLO). Qualitative analyses verified content validity. Exploratory and confirmatory factor analyses tested the factor structure. Multigroup analyses supported the structural invariance across gender, age, and relationship status. Both factors showed adequate discriminant validity and internal consistency, and good 3-week period test-retest reliability. Associations between the FICQ and insecure attachment orientations demonstrated convergent validity. The association between the FICQ and relationship satisfaction above and beyond a preexisting measure offered criterion validity. By going beyond traditional self-revelation-focused conception of fear of intimacy, that is, by proposing a bi-dimensional structure to fear of intimacy, we believe that this new measure will contribute to future research on fear of intimacy.

The “Big Two” in Political Communication

2013 ◽  
Vol 44 (2) ◽  
pp. 117-128 ◽  
Author(s):  
Mauro Bertolotti ◽  
Patrizia Catellani ◽  
Karen M. Douglas ◽  
Robbie M. Sutton
Keyword(s):  
Political Communication ◽  
Experimental Studies ◽  
Two Dimensions ◽  
Political Sophistication

In two experimental studies (conducted in Britain and Italy), participants read about a politician answering to leadership- versus morality-related allegations using either downward counterfactuals (“things could have been worse, if ...”) or upward counterfactuals (“things could have been better, if ...”). Downward messages increased the perception of the politician’s leadership, while both downward and upward messages increased morality perception. Political sophistication moderated the effect of message direction, with downward messages increasing perceived morality in low sophisticates and upward messages increasing perceived morality in high sophisticates. In the latter group, the acknowledgment of an intent to take responsibility mediated morality judgment. Results were consistent across different countries, highlighting previously unexplored effects of communication on the perception of the “Big Two” dimensions.

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