Monolayer 2D ZrTe2 transition metal dichalcogenide as nanoscatter for random laser action.

We demonstrate random laser emission from Rhodamine 6G with ZrTe2 transition metal dichalcogenide (TMD) as nanoscatters, both in powder and 2D nanoflakes liquid suspension. The 2D semimetal ZrTe2 was synthesized by a modified redox exfoliation method to provide single layer TMD, which was employed for the first time as the scatter medium to provide feedback in an organic gain medium random laser. In order to exploit random laser emission and its threshold value, replica symmetry breaking leading to a photonic paramagnetic to photonic spin glass transition in both 2D and 3D (powder) ZrTe2 was demonstrated. One important aspect of mixing organic dyes with ZrTe2 is that there is no chemical reaction leading to dye degradation, demonstrated by operating over more than 2 hours of pulsed (5 Hz) random laser emission.

Nonlinear effects and photonic phase transitions in Nd3+-doped nanocrystal-based random lasers.

The interplay between gain and scattering of light propagating in disordered media allows operation of random lasers (RLs)-lasers without conventional optical cavities. In the present paper, we review our recent contributions in this area, which include the demonstration of self-second-harmonic and self-sum-frequency generation, the characterization of Lévy's statistics of the output intensity fluctuations, and replica symmetry breaking (analogue to the spin-glass phase transition) by RLs based on nanocrystals containing trivalent neodymium ions.

A random laser based on electrospun polymeric composite nanofibers with dual-size distribution.

Electrospun fiber-based random lasers are environment-friendly flexible systems in which waveguiding/scattering processes provided by their structure with a broad distribution of diameters are essential elements to generate a suitable lasing mechanism. In this work, we prepared electrospun fibers with dual-size diameter distribution (above and below the critical value for waveguiding), allowing that both optical processes can be established in the polymer network. As a result, random laser emission was observed for the electrospun fibers presenting dual-size diameters with rhodamine 6G as the gain medium, characterizing the combination of waveguiding/scattering as an adequate condition for development of organic nanofibrous random lasers. Degradation assays were also performed in order to evaluate the prolonged use of such random laser systems.

Asequibilidad de cerveza y bebidas azucaradas para 15 países de América Latina

[RESUMEN]. Objetivos. El objetivo de este trabajo fue analizar la evolución de la asequibilidad de la cerveza y de las gaseosas para quince países de América Latina. Métodos. Los datos corresponden a estadísticas oficiales de índices de precios de cerveza y gaseosas/refrescos, índice de precios al consumidor e índice de salarios nominales en frecuencia mensual. El método se basa en realizar un análisis econométrico, mediante series temporales, para medir el valor esperado de la tasa de crecimiento del indicador de asequibilidad absoluta (utilizando salarios nominales) o relativa (usando precios generales) de las gaseosas y de las cervezas. Resultados. En nueve de los quince países analizados, la asequibilidad (absoluta o relativa), ya sea de bebidas azucaradas o cervezas, ha aumentado de forma estadísticamente significativa. En el caso de las bebidas azucaradas, la asequibilidad absoluta aumentó en cinco países (Chile, Colombia, Costa Rica, Ecuador y Uruguay) y disminuyó en México. En el caso de la cerveza, aumentó en Colombia y Ecuador, se mantuvo inalterada en Argentina, Brasil, Chile, Costa Rica y Uruguay, y se redujo en México. Conclusiones. A pesar de que la mayoría de los países poseen impuestos a la cerveza y a las bebidas azucaradas, su efecto en los precios no ha sido suficiente para reducir su asequibilidad en todos los países de la muestra. Los impuestos deberían modificarse para reducir la asequibilidad de estas bebidas y afectar su consumo.

[ABSTRACT]. Objective. The objective of this study was to look at trends in the affordability of beer and soft drinks in 15 Latin American countries. Methods. The data correspond to government statistics pertaining to price indices for beer and soft drinks, the consumer price index, and the nominal wage index based on monthly frequency. The methods involved the performance of an econometric analysis, using time series, to measure the expected rate of increase in the absolute affordability indicator (using nominal prices) or the relative affordability indicator (using general prices) for soft drinks and beers. Results. In nine of the 15 countries analyzed, the affordability of soft drinks or beer (whether absolute or relative) has shown a statistically significant increase. In the case of soft drinks, absolute affordability increased in five countries (Chile, Colombia, Costa Rica, Ecuador, and Uruguay) and decreased in Mexico. In the case of beer, it increased in Colombia and Ecuador, remained unchanged in Argentina, Brazil, Chile, Costa Rica, and Uruguay, and dropped in Mexico. Conclusions. Although most countries levy taxes on beer and soft drinks, the effect of such taxes on price has not been enough to reduce the affordability of these products in all countries in the sample. Taxes should be modified to make these beverages less affordable and have an impact on their consumption.

[RESUMO]. Objetivos. Analisar a evolução da acessibilidade a cervejas e refrigerantes em 15 países da América Latina. Métodos. Os dados representam estatísticas oficiais dos índices de preços de cervejas e refrigerantes, índice de preços ao consumidor e índice mensal do salário nominal. A metodologia do estudo foi uma análise econométrica com séries temporais para avaliar a taxa esperada de crescimento do indicador de acessibilidade absoluta (com base no salário nominal) ou relativa (com base nos preços gerais) de cervejas e refrigerantes. Resultados. Houve um aumento significativo da acessibilidade (absoluta ou relativa) a cervejas ou refrigerantes em 9 dos 15 países analisados. Com relação aos refrigerantes, houve um aumento da acessibilidade absoluta em cinco países (Chile, Colômbia, Costa Rica, Equador e Uruguai), com uma redução observada no México. Com relação às cervejas, houve um aumento da acessibilidade na Colômbia e Equador, não se observou mudança na Argentina, Brasil, Chile, Costa Rica e Uruguai e ocorreu uma redução no México. Conclusões. Embora exista tributação para cervejas e refrigerantes na maioria dos países, o efeito nos preços não tem sido suficiente para reduzir a acessibilidade a estes produtos em todos os países da amostra estudada. É preciso reformar a tributação a fim de reduzir a acessibilidade e o consumo destas bebidas.

[Affordability of beer and soft drinks in 15 Latin American countriesAcessibilidade a cervejas e refrigerantes em 15 países da América Latina]. / Asequibilidad de cerveza y bebidas azucaradas para 15 países de América Latina.

OBJECTIVE: The objective of this study was to look at trends in the affordability of beer and soft drinks in 15 Latin American countries. METHODS: The data correspond to government statistics pertaining to price indices for beer and soft drinks, the consumer price index, and the nominal wage index based on monthly frequency. The methods involved the performance of an econometric analysis, using time series, to measure the expected rate of increase in the absolute affordability indicator (using nominal prices) or the relative affordability indicator (using general prices) for soft drinks and beers. RESULTS: In nine of the 15 countries analyzed, the affordability of soft drinks or beer (whether absolute or relative) has shown a statistically significant increase. In the case of soft drinks, absolute affordability increased in five countries (Chile, Colombia, Costa Rica, Ecuador, and Uruguay) and decreased in Mexico. In the case of beer, it increased in Colombia and Ecuador, remained unchanged in Argentina, Brazil, Chile, Costa Rica, and Uruguay, and dropped in Mexico. CONCLUSIONS: Although most countries levy taxes on beer and soft drinks, the effect of such taxes on price has not been enough to reduce the affordability of these products in all countries in the sample. Taxes should be modified to make these beverages less affordable and have an impact on their consumption.

OBJETIVOS: Analisar a evolução da acessibilidade a cervejas e refrigerantes em 15 países da América Latina. MÉTODOS: Os dados representam estatísticas oficiais dos índices de preços de cervejas e refrigerantes, índice de preços ao consumidor e índice mensal do salário nominal. A metodologia do estudo foi uma análise econométrica com séries temporais para avaliar a taxa esperada de crescimento do indicador de acessibilidade absoluta (com base no salário nominal) ou relativa (com base nos preços gerais) de cervejas e refrigerantes. RESULTADOS: Houve um aumento significativo da acessibilidade (absoluta ou relativa) a cervejas ou refrigerantes em 9 dos 15 países analisados. Com relação aos refrigerantes, houve um aumento da acessibilidade absoluta em cinco países (Chile, Colômbia, Costa Rica, Equador e Uruguai), com uma redução observada no México. Com relação às cervejas, houve um aumento da acessibilidade na Colômbia e Equador, não se observou mudança na Argentina, Brasil, Chile, Costa Rica e Uruguai e ocorreu uma redução no México. CONCLUSÕES: Embora exista tributação para cervejas e refrigerantes na maioria dos países, o efeito nos preços não tem sido suficiente para reduzir a acessibilidade a estes produtos em todos os países da amostra estudada. É preciso reformar a tributação a fim de reduzir a acessibilidade e o consumo destas bebidas.

Asequibilidad de cerveza y bebidas azucaradas para 15 países de América Latina / Affordability of beer and soft drinks in 15 Latin American countries / Acessibilidade a cervejas e refrigerantes em 15 países da América Latina

RESUMEN Objetivos El objetivo de este trabajo fue analizar la evolución de la asequibilidad de la cerveza y de las gaseosas para quince países de América Latina. Métodos Los datos corresponden a estadísticas oficiales de índices de precios de cerveza y gaseosas/refrescos, índice de precios al consumidor e índice de salarios nominales en frecuencia mensual. El método se basa en realizar un análisis econométrico, mediante series temporales, para medir el valor esperado de la tasa de crecimiento del indicador de asequibilidad absoluta (utilizando salarios nominales) o relativa (usando precios generales) de las gaseosas y de las cervezas. Resultados En nueve de los quince países analizados, la asequibilidad (absoluta o relativa), ya sea de bebidas azucaradas o cervezas, ha aumentado de forma estadísticamente significativa. En el caso de las bebidas azucaradas, la asequibilidad absoluta aumentó en cinco países (Chile, Colombia, Costa Rica, Ecuador y Uruguay) y disminuyó en México. En el caso de la cerveza, aumentó en Colombia y Ecuador, se mantuvo inalterada en Argentina, Brasil, Chile, Costa Rica y Uruguay, y se redujo en México. Conclusiones A pesar de que la mayoría de los países poseen impuestos a la cerveza y a las bebidas azucaradas, su efecto en los precios no ha sido suficiente para reducir su asequibilidad en todos los países de la muestra. Los impuestos deberían modificarse para reducir la asequibilidad de estas bebidas y afectar su consumo.

ABSTRACT Objective The objective of this study was to look at trends in the affordability of beer and soft drinks in 15 Latin American countries. Methods The data correspond to government statistics pertaining to price indices for beer and soft drinks, the consumer price index, and the nominal wage index based on monthly frequency. The methods involved the performance of an econometric analysis, using time series, to measure the expected rate of increase in the absolute affordability indicator (using nominal prices) or the relative affordability indicator (using general prices) for soft drinks and beers. Results In nine of the 15 countries analyzed, the affordability of soft drinks or beer (whether absolute or relative) has shown a statistically significant increase. In the case of soft drinks, absolute affordability increased in five countries (Chile, Colombia, Costa Rica, Ecuador, and Uruguay) and decreased in Mexico. In the case of beer, it increased in Colombia and Ecuador, remained unchanged in Argentina, Brazil, Chile, Costa Rica, and Uruguay, and dropped in Mexico. Conclusions Although most countries levy taxes on beer and soft drinks, the effect of such taxes on price has not been enough to reduce the affordability of these products in all countries in the sample. Taxes should be modified to make these beverages less affordable and have an impact on their consumption.

RESUMO Objetivos Analisar a evolução da acessibilidade a cervejas e refrigerantes em 15 países da América Latina. Métodos Os dados representam estatísticas oficiais dos índices de preços de cervejas e refrigerantes, índice de preços ao consumidor e índice mensal do salário nominal. A metodologia do estudo foi uma análise econométrica com séries temporais para avaliar a taxa esperada de crescimento do indicador de acessibilidade absoluta (com base no salário nominal) ou relativa (com base nos preços gerais) de cervejas e refrigerantes. Resultados Houve um aumento significativo da acessibilidade (absoluta ou relativa) a cervejas ou refrigerantes em 9 dos 15 países analisados. Com relação aos refrigerantes, houve um aumento da acessibilidade absoluta em cinco países (Chile, Colômbia, Costa Rica, Equador e Uruguai), com uma redução observada no México. Com relação às cervejas, houve um aumento da acessibilidade na Colômbia e Equador, não se observou mudança na Argentina, Brasil, Chile, Costa Rica e Uruguai e ocorreu uma redução no México. Conclusões Embora exista tributação para cervejas e refrigerantes na maioria dos países, o efeito nos preços não tem sido suficiente para reduzir a acessibilidade a estes produtos em todos os países da amostra estudada. É preciso reformar a tributação a fim de reduzir a acessibilidade e o consumo destas bebidas.

Replica Symmetry Breaking in the Photonic Ferromagneticlike Spontaneous Mode-Locking Phase of a Multimode Nd:YAG Laser.

We demonstrate the replica symmetry breaking (RSB) phenomenon in the spontaneous mode-locking regime of a multimode Q-switched Nd:YAG laser. The underlying mechanism is quite distinct from that of the RSB recently observed in random lasers. Here, there is no random medium and the phase is not glassy with incoherently oscillating modes as in random lasers. Instead, in each pulse a specific subset of longitudinal modes are activated in a nondeterministic way, whose coherent oscillation dominates and frustrates the others. The emergence of RSB coincides with the onset of ultrashort pulse generation typical of the spontaneous mode-locking regime, both occurring at the laser threshold. On the other hand, when high losses are introduced, RSB is inhibited and only the amplified stimulated emission with replica symmetry is observed. Our results disclose the only theoretically predicted photonic phase with RSB that remained unobserved so far.

Turbulence hierarchy in a random fibre laser.

Turbulence is a challenging feature common to a wide range of complex phenomena. Random fibre lasers are a special class of lasers in which the feedback arises from multiple scattering in a one-dimensional disordered cavity-less medium. Here we report on statistical signatures of turbulence in the distribution of intensity fluctuations in a continuous-wave-pumped erbium-based random fibre laser, with random Bragg grating scatterers. The distribution of intensity fluctuations in an extensive data set exhibits three qualitatively distinct behaviours: a Gaussian regime below threshold, a mixture of two distributions with exponentially decaying tails near the threshold and a mixture of distributions with stretched-exponential tails above threshold. All distributions are well described by a hierarchical stochastic model that incorporates Kolmogorov's theory of turbulence, which includes energy cascade and the intermittence phenomenon. Our findings have implications for explaining the remarkably challenging turbulent behaviour in photonics, using a random fibre laser as the experimental platform.

Observation of photonic paramagnetic to spin-glass transition in a specially designed TiO2 particle-based dye-colloidal random laser.

Colloidal-based random lasers (RLs) are highly efficient and have been exploited in a wide range of geometries. However, in the particular case of ethanol solutions of rhodamines and TiO2 particles, the RL behavior is quite unstable due to the fast precipitation of the particles. In this Letter, specially designed amorphous TiO2 particles were synthesized by a sol-gel method, preventing the degradation of the RL for long operating lifetimes of over 105 shots. As a consequence, this modified colloidal RL allowed the observation of a clear replica-symmetry-breaking phase transition from the paramagnetic fluorescent to spin-glass RL behavior, which has not been observed in the system with nonfunctionalized TiO2 particles.

Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes.

Ultraviolet and blue light were obtained by nonlinear frequency conversion in a random laser (RL) based on Nd0.10Y0.90Al3(BO3)4 nanocrystalline powder. RL operation at 1062 nm, due to the (4)F3/2 → (4)I11/2 transition of neodymium ions (Nd(3+)), was achieved by exciting the Nd(3+) with a tunable beam from 680 to 920 nm covering the ground state absorption transitions to the (4)F9/2, ((4)F7/2,(4)S3/2), ((4)F5/2,(2)H9/2), and (4)F3/2 states. Light from 340 to 460 nm was obtained via the second-harmonic generation of the excitation beam while tunable blue light, from 417 to 486 nm, was generated by self-sum-frequency mixing between the excitation beam and the RL emission.

Observation of Lévy distribution and replica symmetry breaking in random lasers from a single set of measurements.

Random lasers have been recently exploited as a photonic platform for studies of complex systems. This cross-disciplinary approach opened up new important avenues for the understanding of random-laser behavior, including Lévy-type distributions of strong intensity fluctuations and phase transitions to a photonic spin-glass phase. In this work, we employ the Nd:YBO random laser system to unveil, from a single set of measurements, the physical origin of the complex correspondence between the Lévy fluctuation regime and the replica-symmetry-breaking transition to the spin-glass phase. A novel unexpected finding is also reported: the trend to suppress the spin-glass behavior for high excitation pulse energies. The present description from first principles of this correspondence unfolds new possibilities to characterize other random lasers, such as random fiber lasers, nanolasers and small lasers, which include plasmonic-based, photonic-crystal and bio-derived nanodevices. The statistical nature of the emission provided by random lasers can also impact on their prominent use as sources for speckle-free laser imaging, which nowadays represents one of the most promising applications of random lasers, with expected progress even in cancer research.