Self-quenching of the semiconductor laser linewidth below the Schawlow-Townes limit by using optical feedback

We demonstrate theoretically and experimentally self-quenching of the fundamental semiconductor laser frequency fluctuations to a level that is orders of magnitude below the Schawlow-Townes limit for a solitary laser. It is shown that the main operative mechanism is the combined action of a frequency-dependent internal loss and amplitude-to-phase coupling. The internal frequency-dependent loss is introduced by means of spectrally narrow external optical feedback, which provides a strong frequency-dependent dispersion. Linewidth reduction by a factor of 2 X 10^3 is demonstrated by using a narrow Doppler-free Faraday resonance in Cs vapor

Trend analysis of the COVID-19 pandemic in China and the rest of the world

The recent epidemic of Coronavirus (COVID-19) that started in China has already been "exported" to more than 140 countries in all the continents, evolving in most of them by local spreading. In this contribution we analyze the trends of the cases reported in all the Chinese provinces, as well as in some countries that, until March 15th, 2020, have more than 500 cases reported. Notably and differently from other epidemics, the provinces did not show an exponential phase. The data available at the Johns Hopkins University site seem to fit well an algebraic sub-exponential growing behavior as was pointed out recently. All the provinces show a clear and consistent pattern of slowing down with growing exponent going nearly zero, so it can be said that the epidemic was contained in China. On the other side, the more recent spread in countries like, Italy, Iran, and Spain show a clear exponential growth, as well as other European countries. Even more recently, US -which was one of the first countries to have an individual infected outside China (Jan 21st, 2020)- seems to follow the same path. We calculate the exponential growth of the most affected countries, showing the evolution along time after the first local case. We identify clearly different patterns in the analyzed data and we give interpretations and possible explanations for them. The analysis and conclusions of our study can help countries that, after importing some cases, are not yet in the local spreading phase, or have just started

A STATISTICAL MODEL FOR STOCK ASSESSMENT OF SOUTHERN BLUEFIN TUNA WITH TEMPORAL CHANGES IN SELECTIVITY

Assessment of the status of southern bluefin tuna (SBT) by Australia and Japan has used a method (ADAPT) that imposes a number of structural restrictions, and is similar to methods used for a number of stocks worldwide. A flexible method for assessment of the SBT population is presented that is much less restrictive and has potentially wide applicability. The three key features are: (1) all fitting to data is within the context of maximum likelihood, (2) catch-at-age data are not assumed to be without error (as in existing methods), but rather to be random variables, while age-specific selectivity is allowed to change over time within the bounds of specific structure, and (3) autocorrelation in recruitment processes is considered within the likelihood framework of the model. While the results suggest the stock has been depleted considerably from its virgin biomass, and are generally consistent with previous assessments, they also indicate that it is not as much below the biomass that will produce maximum suitable yield as previously estimated and that the extent of stock rebuilding necessary may not be as large as has been argued. The available data are shown to provide little information on the steepness parameter of the stock-recruitment function, and hence on sustainable catch levels for the stock.Afr. J. mar. Sci. 25: 331–36

A statistical model for stock assessment of southern bluefin tuna with temporal changes in selectivity

Assessment of the status of southern bluefin tuna (SBT) by Australia and Japan has used a method (ADAPT) that imposes a number of structural restrictions, and is similar to methods used for a number of stocks world-wide. A flexible method for assessment of the SBT population is presented that is much less restrictive and has potentially wide applicability. The three key features are: (1) all fitting to data is within the context of maximum likelihood, (2) catch-at-age data are not assumed to be without error (as in existing methods), but rather to be random variables, while age-specific selectivity is allowed to change over time within the bounds of specific structure, and (3) autocorrelation in recruitment processes is considered within the likelihood framework of the model. While the results suggest the stock has been depleted considerably from its virgin biomass, and are generally consistent with previous assessments, they also indicate that it is not as much below the biomass that will produce maximum suitable yield as previously estimated and that the extent of stock rebuilding necessary may not be as large as has been argued. The available data are shown to provide little information on the steepness parameter of the stock-recruitment function, and hence on sustainable catch levels for the stock

Análise empírica dos atos de concentrações verticais : como o CADE tem endereçado os efeitos unilaterais e coordenados em seus julgados?

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Direito, 2019.O presente trabalho apresenta uma análise jurisprudencial dos efeitos concorrenciais unilaterais e coordenados alegados em votos vencedores no Tribunal do Conselho Administrativo de Defesa Econômica (Cade) entre 2014 e 2018, quando do julgamento de integrações verticais em Atos de Concentração (ACs). Foram considerados como ACs verticais aqueles que envolveram empresas atuantes em dois nichos de mercado diferentes, em uma mesma cadeia produtiva, não excepcionando a existência de sobreposições horizontais ou integrações conglomerais entre elas, sendo identificados 38 ACs com integrações verticais, mas apenas 16 deles tiveram seus efeitos verticais detalhados pelo Tribunal do Cade. O presente estudo visa compreender os tipos de efeitos alegados pelo Tribunal do Cade, por meio de uma análise interpretativa, utilizando-se como base as definições presentes no Guia de Concentrações Não-Horizontais da União Europeia. Dos resultados mais relevantes do estudo, foram identificados principalmente efeitos unilaterais decorrentes de integrações verticais, sendo a categoria de discriminação a montante com efeitos a jusante a mais comum delas.This study presents a jurisprudential analysis of competitive effects, arising from vertical integrations in mergers, alleged in winning votes in the Tribunal of the Administrative Council for Economic Defense (Cade) between 2014 and 2018. For this research, it was considered as vertical mergers all of those cases that involved companies acting in two different levels of the same market chain, not excluding the existence of horizontal integrations and conglomerate relations. From the cases analyzed, 38 mergers were identified with vertical integrations, but only 16 of them had vertical effects detailed by the Tribunal. This research aims to analyze the kind of effects alleged by Cade’s Tribunal, via an interpretative analysis, using the European Union Non-horizontal Merger Guidelines as a basis for the definitions used. Regarding the most relevant results of the study, the unilateral effects because of the vertical integration present in the cases were the most common effects identified, especially the upstream foreclosure