Mode-selective quantization and multimodal effective models for spherically layered systems

We propose a geometry-specific, mode-selective quantization scheme in coupled field-emitter systems which makes it easy to include material and geometrical properties, intrinsic losses as well as the positions of an arbitrary number of quantum emitters. The method is presented through the example of a spherically symmetric, non-magnetic, arbitrarily layered system. We follow it up by a framework to project the system on simpler, effective cavity QED models. Maintaining a well-defined connection to the original quantization, we derive the emerging effective quantities from the full, mode-selective model in a mathematically consistent way. We discuss the uses and limitations of these effective models

Pre-determining the location of electromigrated gaps by nonlinear optical imaging

In this paper we describe a nonlinear imaging method employed to spatially map the occurrence of constrictions occurring on an electrically-stressed gold nanowire. The approach consists at measuring the influence of a tightly focused ultrafast pulsed laser on the electronic transport in the nanowire. We found that structural defects distributed along the nanowire are efficient nonlinear optical sources of radiation and that the differential conductance is significantly decreased when the laser is incident on such electrically-induced morphological changes. This imaging technique is applied to pre-determined the location of the electrical failure before it occurs.Comment: 3 figure

Quantum Plasmonics with multi-emitters: Application to adiabatic control

We construct mode-selective effective models describing the interaction of N quantum emitters (QEs) with the localised surface plasmon polaritons (LSPs) supported by a spherical metal nanoparticle (MNP) in an arbitrary geometric arrangement of the QEs. We develop a general formulation in which the field response in the presence of the nanosystem can be decomposed into orthogonal modes with the spherical symmetry as an example. We apply the model in the context of quantum information, investigating on the possibility of using the LSPs as mediators of an efficient control of population transfer between two QEs. We show that a Stimulated Raman Adiabatic Passage configuration allows such a transfer via a decoherence-free dark state when the QEs are located on the same side of the MNP and very closed to it, whereas the transfer is blocked when the emitters are positioned at the opposite sides of the MNP. We explain this blockade by the destructive superposition of all the interacting plasmonic modes

3D homogenised strength criterion for masonry: application to drystone retaining walls

A 3D strength criterion for masonry is constructed based on yield design theory. Yield design homogenisation provides a rigorous theoretical framework to determine the yield strength properties of a periodic medium, based on the properties of its constituent materials. First, theoretical basis of 2D homogenisation of periodic media, and more particularly its application in the framework of yield design, will be retrieved. Then, 2D principles are extended to exhibit a 3D domain of running-bond masonry. This criterion is finally used to assess the stability of a drystone retaining wall loaded by an axle load, and theoretical results are compared to experimental data. Perspectives on this work are given as a conclusion

Collective strong coupling in a plasmonic nanocavity

Quantum plasmonics extends cavity quantum electrodynamics (cQED) concepts to the nanoscale, taking benefit from the strongly subwavelength confinement of the plasmon modes supported by metal nanostructures. In this work, we describe in detail collective strong coupling to a plasmonic nanocavity. Similarities and differences to cQED are emphasized. We notably observe that the Rabi splitting can strongly deviate from the standard $\sqrt{N_e}\Delta \Omega_1$ law, where $N_e$ is the number of emitters and $\Delta \Omega_1$ the Rabi splitting for a single emitter. In addition, we discuss the collective Lamb shift and the role of quantum corrections to the emission spectra

Loss of Melanopsin Photoreception and Antagonism of the Histamine H3 Receptor by Ciproxifan Inhibit Light-Induced Sleep in Mice

Light has direct effects on sleep and wakefulness causing arousal in diurnal animals and sleep in nocturnal animals. In the present study, we assessed the modulation of light-induced sleep by melanopsin and the histaminergic system by exposing mice to millisecond light flashes and continuous light respectively. First, we show that the induction of sleep by millisecond light flashes is dose dependent as a function of light flash number. We found that exposure to 60 flashes of light occurring once every 60 seconds for 1-h (120-ms of total light over an hour) induced a similar amount of sleep as a continuous bright light pulse. Secondly, the induction of sleep by millisecond light flashes was attenuated in the absence of melanopsin when animals were presented with flashes occurring every 60 seconds over a 3-h period beginning at ZT13. Lastly, the acute administration of a histamine H3 autoreceptor antagonist, ciproxifan, blocked the induction of sleep by a 1-h continuous light pulse during the dark period. Ciproxifan caused a decrease in NREMS delta power and an increase in theta activity during both sleep and wake periods respectively. The data suggest that some form of temporal integration occurs in response to millisecond light flashes, and that this process requires melanopsin photoreception. Furthermore, the pharmacological data suggest that the increase of histaminergic neurotransmission is sufficient to attenuate the light-induced sleep response during the dark period.Down Syndrome Research and Treatment FoundationResearch Down Syndrome Organizatio

Cosmic ray tests of a GEM-based TPC prototype operated in Ar-CF4-isobutane gas mixtures

Argon with an admixture of CF4 is expected to be a good candidate for the gas mixture to be used for a time projection chamber (TPC) in the future linear collider experiment because of its small transverse diffusion of drift electrons especially under a strong magnetic field. In order to confirm the superiority of this gas mixture over conventional TPC gases we carried out cosmic ray tests using a GEM-based TPC operated mostly in Ar-CF4-isobutane mixtures under 0 - 1 T axial magnetic fields. The measured gas properties such as gas gain and transverse diffusion constant as well as the observed spatial resolution are presented.Comment: 22 pages, 18 figures. Published in Nuclear Instruments and Methods in Physics Research A. Fig. 3 in the introduction was corrected since it had not been properly normalized. Minor corrections and no changes in the conclusio

Precise determination of stellar parameters of the ZZ Ceti and DAZ white dwarf GD 133 through asteroseismology

An increasing number of white dwarf stars show atmospheric chemical composition polluted by heavy elements accreted from debris disk material. The existence of such debris disks strongly suggests the presence of one or more planet(s) whose gravitational interaction with rocky planetesimals is responsible for their disruption by tidal effect. The ZZ Ceti pulsator and polluted DAZ white dwarf GD 133 is a good candidate for searching for such a potential planet. We started in 2011 a photometric follow-up of its pulsations. As a result of this work in progress, we used the data gathered from 2011 to 2015 to make an asteroseismological analysis of GD 133, providing the star parameters from a best fit model with $M$/$M_{\odot}$ = 0.630 $\pm$ 0.002, $T_{\rm eff}$ = 12400 K $\pm$ 70 K, log($M_{\rm He}/M$) = -2.00 $\pm$ 0.02, log($M_{\rm H}/M$) = -4.50 $\pm$ 0.02 and determining a rotation period of $\approx$ 7 days.Comment: 10 pages, 13 figures, accepted by MNRA

Pumilio-2 Function in the Mouse Nervous System

Coordinated mRNA translation at the synapse is increasingly recognized as a critical mechanism for neuronal regulation. Pumilio, a translational regulator, is known to be involved in neuronal homeostasis and memory formation in Drosophila. Most recently, the mammalian Pumilio homolog Pumilio-2 (Pum2) has been found to play a role in the mammalian nervous system, in particular in regulating morphology, arborization and excitability of neuronal dendrites, in vitro. However, the role of Pum2 in vivo remains unclear. Here, we report our investigation of the functional and molecular consequences of Pum2 disruption in vivo using an array of neurophysiology, behavioral and gene expression profiling techniques. We used Pum2-deficient mice to monitor in vivo brain activity using EEG and to study behavior traits, including memory, locomotor activity and nesting capacities. Because of the suspected role of Pum2 in neuronal excitability, we also examined the susceptibility to seizure induction. Finally, we used a quantitative gene expression profiling assay to identify key molecular partners of Pum2. We found that Pum2-deficient mice have abnormal behavioral strategies in spatial and object memory test. Additionally, Pum2 deficiency is associated with increased locomotor activity and decreased body weight. We also observed environmentally-induced impairment in nesting behavior. Most importantly, Pum2-deficient mice showed spontaneous EEG abnormalities and had lower seizure thresholds using a convulsing dosage of pentylenetetrazole. Finally, some genes, including neuronal ion channels, were differentially expressed in the hippocampus of Pum2-deficient mice. These findings demonstrate that Pum2 serves key functions in the adult mammalian central nervous system encompassing neuronal excitability and behavioral response to environmental challenges