Search results for "LONG"
showing 10 items of 3969 documents
VLBI Observations of a Complete Sample of Radio Galaxies. VII. Study of the FR I Sources 3C 31, 4C 35.03, and 3C 264
1997
We present results from global VLBI and VLA observations of three FanaroU-Riley type I radio gal- axies, 3C 31, 4C 35.03, and 3C 264, at a frequency of 5 GHz. In all three cases, we observe asymmetric parsec-scale structures consisting of a compact core and a single jet pointing in the direction of the more prominent kiloparsec jet. We interpret such alignment as evidence for the relativistic nature of FR I radio jets at parsec scales. Comparing the VLBI and VLA images of these sources, we —nd a progressive deceleration of the plasma —ow from parsec to kiloparsec scales. We consider another —ve FR I radio galaxies studied previously by us and —nd that, in a set of eight FR I objects, the es…
The nonlinear Schrodinger equation and the propagation of weakly nonlinear waves in optical fibres and on the water surface
2015
International audience; The dynamics of waves in weakly nonlinear dispersive media can be described by the nonlinear Schrödinger equation (NLSE). An important feature of the equation is that it can be derived in a number of different physical contexts; therefore, analogies between different fields, such as for example fiber optics, water waves, plasma waves and Bose–Einstein condensates, can be established. Here, we investigate the similarities between wave propagation in optical Kerr media and water waves. In particular, we discuss the modulation instability (MI) in both media. In analogy to the water wave problem, we derive for Kerr-media the Benjamin–Feir index, i.e. a nondimensional par…
Trial for the long neutron counter TETRA using $^{96,97}$Rb radioactive sources
2019
International audience; The TETRA long neutron counter is operated at ALTO ISOL facility behind the PARRNe mass separator. TETRA has been proven to be a unique instrument for measurements of β-decay properties of short-lived neutron-rich nuclei having applications for the nuclear structure and/or astrophysical r-process calculations. A proper calibration of TETRA can allow validation of the experimental procedure used for determination of β-delayed one-neutron emission probabilities (P1n). It requires the use of a well-known β-neutron decaying radioactive source which can be only produced and measured on-line due to its short half-life. Thus, the present paper reports on measurements of P1n…
Charge compensation by long-period reconstruction in strongly polar lithium niobate surfaces
2013
The microscopic structure of the polar (000$\overline{1}$) and (0001) surfaces of lithium niobate is investigated by atomic-resolution frequency modulation atomic force microscopy and first-principles calculations. It is found that the surface reconstructs at annealing temperatures sufficiently high to drive off external adsorbates. In particular a ($\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7}$)$R$19.1${}^{\ensuremath{\circ}}$ reconstruction is found for the (000$\overline{1}$) surface. Density-functional theory calculations show that---apart from the $(\sqrt{7}\ifmmode\times\else\texttimes\fi{}\sqrt{7})$---a series of adatom-induced surface reconstructions exist that lower the surfa…
Dyakonov surface waves in lossy metamaterials
2015
We analyze the existence of localized waves in the vicinities of the interface between two dielectrics, provided one of them is uniaxial and lossy. We found two families of surface waves, one of them approaching the well-known Dyakonov surface waves (DSWs). In addition, a new family of wave fields exists which are tightly bound to the interface. Although its appearance is clearly associated with the dissipative character of the anisotropic material, the characteristic propagation length of such surface waves might surpass the working wavelength by nearly two orders of magnitude. This research was funded by the Spanish Ministry of Economy and Competitiveness under the Project TEC2013-50416-E…
Corrections to “Light Modulation Based on Fiber Cladding Mode Coupling Between Concatenated Long-Period Gratings” [Feb 1 152-154]
2011
In the above paper (ibid., vol. 23, no. 3, pp. 152-154, Feb. 1, 2011), there is an error in the eighth line of the abstract. The correct sentence is presented here.
Video-Analysis of the flight of a model aircraft
2011
A video-analysis software tool has been employed in order to measure the steady-state values of the kinematics variables describing the longitudinal behaviour of a radio-controlled model aircraft during take-off, climbing and gliding. These experimental results have been compared with the theoretical steady-state configurations predicted by the phugoid model for longitudinal flight. A comparison with the parameters and performance of the full-size aircraft has also been outlined.
Millimeter VLBI of NGC 1052: Dynamics
2016
The LINER galaxy NGC 1052 is an ideal target to study the innermost regions of active galactic nuclei (AGN), given its close distance of about 20 Mpc. The source was observed at 29 epochs from 2005 to 2009 with the Very Long Baseline Array (VLBA) at 43 GHz. Here, we present a kinematic study of its twin-jet system from a subset of 9 epochs at 43 GHz carried out in 2005 and 2006, finding a bright central feature as the dynamic center. The resulting mean velocities of β = v / c = 0 . 46 ± 0 . 08 and β = 0 . 69 ± 0 . 02 for the western and eastern jet, respectively, give hints towards higher velocities in the eastern jet.
Long-lived particles at the energy frontier: the MATHUSLA physics case
2019
We examine the theoretical motivations for long-lived particle (LLP) signals at the LHC in a comprehensive survey of Standard Model (SM) extensions. LLPs are a common prediction of a wide range of theories that address unsolved fundamental mysteries such as naturalness, dark matter, baryogenesis and neutrino masses, and represent a natural and generic possibility for physics beyond the SM (BSM). In most cases the LLP lifetime can be treated as a free parameter from the $\mu$m scale up to the Big Bang Nucleosynthesis limit of $\sim 10^7$m. Neutral LLPs with lifetimes above $\sim$ 100m are particularly difficult to probe, as the sensitivity of the LHC main detectors is limited by challenging …
Equilibrium/steady-state concept in phytoplankton ecology
2003
This paper summarises the outcomes of the 13th Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP). The authors mostly addressed their contributions on the following topics: the effect of trophic state on the attainment of a steady-state; the establishment of equilibria in deep and shallow lakes; the role of spatial heterogeneity, disturbance, and stress in the establishment of equilibrium assemblages; the mechanisms leading to the steady state; the frequency and longevity of equilibrium phases, and the role of morphological and physiological plasticity of phytoplankton in maintaining the (apparently) same populations under different environmental condition…