Theoretical study of loss compensation in long-range dielectric loaded surface plasmon polariton waveguides

In this paper, a theoretical study of loss compensation in long-range dielectric loaded surface plasmon waveguides (LR-DLSPPs) is presented. Although extendable to other gain materials, rare-earth doped double tungstates are used as gain material in this work. Two different structures are studied and the effect of the different waveguide geometrical parameters on the material gain required to fully compensate the propagation losses are reported. The simulations were performed at 1.55 micrometer wavelength. A material gain as low as 12.5 dB/cm was determined as sufficient to obtain complete loss compensation in one of the proposed waveguide structures supporting sub-micron lateral mode dimension

Absolute elastic differential cross sections for electron scattering by C6H5CH3 and C6H5CF3 at 1.5–200 eV: a comparative experimental and theoretical study with C6H6

We present absolute differential cross sections DCS for elastic scattering from two benzene derivatives C6H5CH3 and C6H5CF3. The crossed-beam method was used in conjunction with the relative flow technique using helium as the reference gas to obtain absolute values. Measurements were carried out for scattering angles 15° –130° and impact energies 1.5–200 eV. DCS results for these two molecules were compared to those of C6H6 from our previous study. We found that 1 these three molecules have DCS with very similar magnitudes and shapes over the energy range 1.5–200 eV, although DCS for C6H5CF3 increase steeply toward lower scattering angles due to the dipole moment induced long-range interaction at 1.5 and 4.5 eV, and 2 that the molecular structure of the benzene ring significantly determines the collision dynamics. From the measured DCS, elastic integral cross sections have been calculated. Furthermore, by employing a corrected form of the independent-atom method known as the screen corrected additive rule, DCS calculations have been carried out without any empirical parameter fittings, i.e., in an ab initio nature. Results show that the calculated DCS are in excellent agreement with the experimental values at 50, 100, and 200 eV

Inter-Annual to Inter-Decadal Variability of Upwelling and Anchovy Population off Northern Chile

The coastal ocean of northern Chile has persistent wind-driven upwelling that produces high nutrient and chlorophyll concentrations in a narrow band along the coast. The objective of this thesis is to study the low frequency temporal variability of the upwelling system, to understand the spatial and temporal changes in the wind field, and how these changes may affect the upwelling and anchovy variability. Data used in this thesis includes time series of wind, sea level, sea surface temperature, and atmospheric pressure at coastal stations, from 1960 to 2003, and oceanographic and acoustic cruises for the period 1993–2003. The time series are analyzed using the STL method (Seasonal Trend Decomposition procedures based on locally weighted regression and smoothed scatter plots (LOESS)), maxima entropy spectral analysis, wavelets, cross spectra, and EOFs (Empirical Orthogonal functions). The wind field from ERS and QuikSCAT satellite radar scatterometers was analyzed. Variability occurred at four frequency bands: quasi-biennial (2–3 years), ENSO (3–8 years), decadal (9–12 years), and interdecadal (13–25 years). The origin of quasi-biennial variability could be explained by means of the Delayed Oscillator Mode. The STL trend shows three regime changes: before 1976 (cold), between 1976 and 1998 (warm), and after 1998 (cold). These regime changes correspond with the changes in anchovy and sardine populations in the Chile-Peru system. During the last five years, there has been a diminution of the upwelling index, SST, sea level, and atmospheric pressure, and more Lasker events (calms). The spatial variability of wind stress in the study area is characterized by a minimum between two maximums located at 15°S and 30°S. The effect of the curvature of the coast, as well as the height of mountains near the coast, produces a unique system, where the wind is forced thermally, reaching a maximum in summer and a minimum in winter, in opposition to the oceanic pattern. In spring and summer the alongshore wind is accelerated by cross-shore pressure gradient changes, producing an intense divergence along the coast. Very near the coast, the wind stress is low, though it increases offshore. The combined effect of both processes produces a convergence outside of the upwelling front. On the scale of days, this convergence could be the origin of the mesoscale eddies that are observed in the zone. This pattern changes during ENSO events. El Niño produced changes in the density, distribution, and the depth of the anchovy schools. The deepening of some schools in the coastal area placed them below normal fishing nets, explaining their fast recovery when the El Niño ends

Completeness and Nonclassicality of Coherent States for Generalized Oscillator Algebras

The purposes of this work are (1) to show that the appropriate generalizations of the oscillator algebra permit the construction of a wide set of nonlinear coherent states in unified form; and (2) to clarify the likely contradiction between the nonclassical properties of such nonlinear coherent states and the possibility of finding a classical analog for them since they are P-represented by a delta function. In (1) we prove that a class of nonlinear coherent states can be constructed to satisfy a closure relation that is expressed uniquely in terms of the Meijer G-function. This property automatically defines the delta distribution as the P-representation of such states. Then, in principle, there must be a classical analog for them. Among other examples, we construct a family of nonlinear coherent states for a representation of the su(1,1) Lie algebra that is realized as a deformation of the oscillator algebra. In (2), we use a beam splitter to show that the nonlinear coherent states exhibit properties like anti-bunching that prohibit a classical description for them. We also show that these states lack second order coherence. That is, although the P-representation of the nonlinear coherent states is a delta function, they are not full coherent. Therefore, the systems associated with the generalized oscillator algebras cannot be considered `classical' in the context of the quantum theory of optical coherence.Comment: 26 pages, 10 figures, minor changes, misprints correcte

Effects of Different Types of Noise on Foreign Accent Adaptation

Understanding foreign-accented speech can be difficult. Comprehension can be further compromised by environmental noise. Previous research has shown that listeners are able to adapt rapidly to a foreign accent. The present study examines how foreign accent (FA) adaptation is affected by two kinds of noise: speech-shaped white noise and competing speech. Native English listeners heard blocks of sentences produced by native-accented or foreign-accented talkers (Korean, Spanish) mixed with either type of noise, and indicated if the word written on the screen and the last word they heard were the same by pressing a button. Results show that listener responses were more accurate (though slower) when sentences were mixed with competing speech than with speech-shaped white noise. These findings suggest that while competing speech made word recognition more effortful, ultimately it was less disruptive than white noise for FA adaptation.Linguistic

Between a 'media circus' and 'seeing justice being done': metajournalistic discourse and the transparency of justice in the debate on filming trials in British newspapers

Public trust in the criminal justice system in England and Wales has been low since the 1990s, and accusations that the system is arcane, lacking transparency, soft on criminals, and removed from the society it serves are common. The government, together with many lawyers, journalists and experts, believe that lifting the ban on televising trials may enhance the transparency of the judicial system, and eventually lead to higher levels of public trust. Drawing on the most systematic content analysis of the coverage of this debate between 1984 and 2016, we analyse how this issue was debated in British national newspapers. In addition to examining how newspapers presented this policy debate, we also explore how the coverage discussed the impact that filming trials could have upon journalistic practice. Our analysis shows how metajournalistic discourse resorts to high-profile and celebrity cases when examining journalistic practice. Newspapers constructed this issue as a quandary between increasing the transparency of the judicial system, and the risk that justice would become sensationalised, ignoring key elements in the debate, and the role that journalists themselves may play in that process