Search results for "waves"
showing 10 items of 1766 documents
Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory
2011
We present the results of searches for dipolar-type anisotropies in different energy ranges above 2.5 × 1017 eV with the surface detector array of the Pierre Auger Observatory, reporting on both the phase and the amplitude measurements of the first harmonic modulation in the right-ascension distribution. Upper limits on the amplitudes are obtained, which provide the most stringent bounds at present, being below 2% at 99% C.L. for EeV energies. We also compare our results to those of previous experiments as well as with some theoretical expectations.
Generation of Structured Light via Nano Structures and Applications
2020
The generation of structured light by means of metasurfaces is presented and the applications in the characterizations of polarization rotation and Pancharatnam-Berry phase are discussed.
Synthesis of Nanoparticles
2012
In this chapter I describe the synthetic methods for the particles used in this work. Initially bare gold nanorods are synthesized , which are used to investigate continuously the growth of bigger nanoparticles and the protein-membrane interaction on a single particle level . To reduce the single particle linewidth and therefore to increase the sensitivity on changes in the refractive index , these rods are coated with a thin silver shell . Another method to increase the sensitivity of nanoparticles is to produce hollow rod-shaped nanorattles, which were synthesized by Yuriy Khalavka . To investigate the polarization depend scattering spectra of different shapes with the RotPOL setup , diff…
Technological and knowledge diffusion link: An international perspective 1870–2019
2021
Abstract Technology diffusion is a necessary but not sufficient condition for knowledge diffusion. Technological waves' impact on education differs across educational levels. We use data for 104 countries on technology diffusion and education from 1870 to 2019. We find six technology waves from 1870 to 2019 had a substantial and statistically significant educational attainment impact using fixed panel data modeling. The impact differs across time and regions, with the most noticeable impact in Advanced economies and Eastern Europe. Asia and the Pacific, Latin America and the Caribbean, Middle East, and North Africa are catching up with lagging Sub-Saharan Africa. The transportation revoluti…
Polar nanoregions in Pb(Mg1/3Nb2/3)O3 (PMN): insights from a supercell approach
2011
Abstract We report construction of a model of polar nanoregions in the PMN relaxor ferroelectric based on first-principles lattice dynamics for chemically ordered supercells [S.A. Prosandeev et al., Phys. Rev. B 70, 134110 (2004)], combined with invariance under permutations and dipole-dipole interaction as a source supporting randomly oriented residual polarization. Representative analytical estimates of polar nanore-gion — supercell mapping reproduce both nonzero local and zero macroscopic polarization of the structure, as well as the temperature change of the supercell anisotropy at cooling and field cooling.
Polarization tensors of planar domains as functions of the admittivity contrast
2014
(Electric) polarization tensors describe part of the leading order term of asymptotic voltage perturbations caused by low volume fraction inhomogeneities of the electrical properties of a medium. They depend on the geometry of the support of the inhomogeneities and on their admittivity contrast. Corresponding asymptotic formulas are of particular interest in the design of reconstruction algorithms for determining the locations and the material properties of inhomogeneities inside a body from measurements of current flows and associated voltage potentials on the body's surface. In this work we consider the two-dimensional case only and provide an analytic representation of the polarization t…
Left-handed neutrino disappearance probe of neutrino mass and character
1996
We explore the sensitivity to a non vanishing neutrino mass offered by dynamical observables, i.e., branching ratios and polarizations. The longitudinal polarization in the C.M. frame decreases by a 4% for $D^+ \rightarrow \tau^+ \nu_\tau$ and $m_{\nu_\tau}=24$ MeV. Taking advantage of the fact that the polarization is a Lorentz variant quantity, we study the polarization effects in a boosted frame. By means of a neutrino beam, produced by a high velocity boosted parent able to flip the neutrino helicity, we find that an enhanced left-handed neutrino deficit, induced by a Wigner rotation, appears.
Optogenetically blocking sharp wave ripple events in sleep does not interfere with the formation of stable spatial representation in the CA1 area of …
2016
During hippocampal sharp wave/ripple (SWR) events, previously occurring, sensory inputdriven neuronal firing patterns are replayed. Such replay is thought to be important for plasticity-related processes and consolidation of memory traces. It has previously been shown that the electrical stimulation-induced disruption of SWR events interferes with learning in rodents in different experimental paradigms. On the other hand, the cognitive map theory posits that the plastic changes of the firing of hippocampal place cells constitute the electrophysiological counterpart of the spatial learning, observable at the behavioral level. Therefore, we tested whether intact SWR events occurring during th…
Long cavity ring fiber mode-locked laser with decreased net value of nonlinear polarization rotation
2019
We investigate a new configuration of a mode-locked fiber laser by using a nonlinear polarization rotation-based design to generate soliton pulses with low repetition rate. Unlike with previously reported configurations, we introduce a Faraday mirror after the first half of the cavity length to counteract the nonlinear polarization rotation effects. The total cavity length is 437 m including a 400-m long twisted SMF-28 fiber. The fiber was twisted to cancel the linear birefringence and to ensure that the polarization ellipticity is not altered as the pulse travels along the fiber. The strict control of polarization yields a stable relation between the polarization state of the pulses propag…
Lower and Middle Cambrian brachiopods from the Iberian Chains and Sierra Morena (Spain)
2021
Brachiopods from the Lower and Middle Cambrian of the Iberian Chains and Sierra Morena are described. The following taxa occur in the Iberian Chains: "Lingulella" sp., Redlichella cf. bohemica (Barrande), Dictyonina radioplicata sp. n., Micromitra sp., Trematobolus simplex (Vogel), Trematobolus borobiensis sp. n. and Jamesella sp. The taxa "Lingulella" sp. and Sibiria? sp. are reported from the Lower Cambrian of Sierra Morena. Brachiopods constitute several distinct associations: the relatively shallow water Trematobolus assemblage near the Lower-Middle Cambrian boundary interval is followed by the deeper DictyoninaRedlichella assemblage. The alternation of these assemblages permit us to i…