Search results for "AAL"

Controlling Exciton Propagation in Organic Crystals through Strong Coupling to Plasmonic Nanoparticle Arrays.

2022

Exciton transport in most organic materials is based on an incoherent hopping process between neighboring molecules. This process is very slow, setting a limit to the performance of organic optoelectronic devices. In this Article, we overcome the incoherent exciton transport by strongly coupling localized singlet excitations in a tetracene crystal to confined light modes in an array of plasmonic nanoparticles. We image the transport of the resulting exciton–polaritons in Fourier space at various distances from the excitation to directly probe their propagation length as a function of the exciton to photon fraction. Exciton–polaritons with an exciton fraction of 50% show a propagation length…

2021

The bosonic analogs of topological insulators have been proposed in numerous theoretical works, but their experimental realization is still very rare, especially for spin systems. Recently, two-dim...

Effects of a uniform acceleration on atom–field interactions

2014

We review some quantum electrodynamical effects related to the uniform acceleration of atoms in vacuum. After discussing the energy level shifts of a uniformly accelerated atom in vacuum, we investigate the atom-wall Casimir-Polder force for accelerated atoms, and the van der Waals/Casimir-Polder interaction between two accelerated atoms. The possibility of detecting the Unruh effect through these phenomena is also discussed in detail.

van der Waals interactions between excited atoms in generic environments

2015

We consider the the van der Waals force involving excited atoms in general environments, constituted by magnetodielectric bodies. We develop a dynamical approach studying the dynamics of the atoms and the field, mutually coupled. When only one atom is excited, our dynamical theory suggests that for large distances the van der Waals force acting on the ground-state atom is monotonic, while the force acting in the excited atom is spatially oscillating. We show how this latter force can be related to the known oscillating Casimir--Polder force on an excited atom near a (ground-state) body. Our force also reveals a population-induced dynamics: for times much larger that the atomic lifetime the …

Small Clusters Made of Helium Atoms

2003

Helium atoms interact very weakly through a van der Waals potential. Nevertheless, they are able to form aggregates or drops with a small number of atoms. This work analyzes the stability of clusters made of 4He atoms, of bosonic nature, clusters made of 3He atoms, of fermionic nature and also mixed aggregates with both kinds of constituents. Some of these drops are predicted to be unstable.

Dynamic Anomalies and their Relation to the Glass Transition: A Neutron Scattering Study of the Glass Forming Van der Waals Liquid Ortho-terphenyl

1991

Neutron scattering experiments on the molecular glass former ortho-terphenyl reveal a dynamic anomaly at a temperature Tc ≈ 290 K well above the calorimetric glass temperature Tg = 243 K. Close above Tc the density autocorrelation function ΦQ(t) shows a two step decay over 4–5 decades in time. The slower component obeys the time-temperature superposition principle. Its line shape can be well parametrized by a Kohlrausch law and is strongly temperature dependent as its relaxation time scales with the shear viscosity. Thus this component is identified with the structural relaxation (α-process). The faster component (β-process) is much less temperature dependent. Its line shape factorizes in a…

Nanoparticles at fluid interfaces.

2017

Nanoparticles at fluid interfaces are becoming a central topic in colloid science studies. Unlike in the case of colloids in suspensions, the description of the forces determining the physical behavior of colloids at interfaces still represents an outstanding problem in the modern theory of colloidal interactions. These forces regulate the formation of complex two-dimensional structures, which can be exploited in a number of applications of technological interest; optical devices, catalysis, molecular electronics or emulsions stabilization. From a fundamental viewpoint and typical for colloidal systems, nanoparticles and microparticles at interfaces are ideal experimental and theoretical mo…

Subcellular localization of bacteriophage PRD1 proteins in Escherichia coli

2014

Bacteria possess an intricate internal organization resembling that of the eukaryotes. The complexity is especially prominent at the bacterial cell poles, which are also known to be the preferable sites for some bacteriophages to infect. Bacteriophage PRD1 is a well-known model serving as an ideal system to study structures and functions of icosahedral internal membrane-containing viruses. Our aim was to analyze the localization and interactions of individual PRD1 proteins in its native host Escherichia coli. This was accomplished by constructing a vector library for production of fluorescent fusion proteins. Analysis of solubility and multimericity of the fusion proteins, as well as their …

Potential for cascading impacts of environmental change and policy on indigenous culture.

2022

AbstractGlobal environmental and societal changes threaten the cultures of indigenous peoples and local communities (IPLC). Despite the importance of IPLC worldviews and knowledge to sustaining human well-being and biodiversity, risks to these cultural resources are commonly neglected in environmental governance, in part because impacts can be indirect and therefore difficult to evaluate. Here, we investigate the connectivity of values associated with the relationship Ngātiwai (a New Zealand Māori tribe) have with their environment. We show that mapping the architecture of values-environment relationships enables assessment of how deep into culture the impacts of environmental change or pol…

Mothers’ self-representations and representations of childhood on social media

2023

Funding Information: This work was supported by Kone Foundation, Academy of Finland (#320370), Strategic Research Council (#327237), Strategic Research Council (#327395), Intimacy in Data-driven Culture (IDA). The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Publisher Copyright: © 2023, Minna Kallioharju, Terhi-Anna Wilska and Annamari Vänskä. Purpose: The purpose of this paper is to examine mothers’ social media accounts that focus on children’s fashion. The authors probed children’s fashion photo practices as representations of the mothers’ extended self and the kind of childhood representations produce…