Experiments in vortex avalanches

Avalanche dynamics is found in many phenomena spanning from earthquakes to the evolution of species. It can be also found in vortex matter when a type II superconductor is externally driven, for example, by increasing the magnetic field. Vortex avalanches associated with thermal instabilities can be an undesirable effect for applications, but "dynamically driven" avalanches emerging from the competition between intervortex interactions and quenched disorder constitute an interesting scenario to test theoretical ideas related with non-equilibrium dynamics. However, differently from the equilibrium phases of vortex matter in type II superconductors, the study of the corresponding dynamical phases - in which avalanches can play a role - is still in its infancy. In this paper we critically review relevant experiments performed in the last decade or so, emphasizing the ability of different experimental techniques to establish the nature and statistical properties of the observed avalanche behavior.Comment: To be published in Reviews of Modern Physics April 2004. 17 page

Continuous monitoring of in vivo chlorophyll a fluorescence in ulva rigida (chlorophyta) submitted to different co2, nutrient and temperature regimes

A Monitoring-PAM fluorometer with high temporal resolution (every 5 min) was used to assess the effects on photosynthesis in Ulva rigida (Chlorophyta) during exposure to 2 different CO2 conditions: current ('LC', 390 ppm), and the predicted level for the year 2100 ('HC', 700 ppm) in a crossed combination with 2 different daily pulsed nitrate concentrations ('LN', 5 mu M and 'HN', 50 mu M) and 2 temperature regimes (ambient and ambient +4 degrees C). Effective quantum yield (Delta F/F-m') in the afternoon was lower under HCLN conditions than under the other treatments. The decrease in Delta F/F-m' from noon to the afternoon was significantly lower under +4 degrees C compared to ambient temperature. Maximal quantum yield (F-v/F-m) decreased during the night with a transient increase 1 to 3 h after sunset, whereas a transient increase in Delta F/F-m' was observed after sunrise. These transient increases have been related to activation/ deactivation of the electron transport rate and the relaxation of non-photochemical quenching. Relative electron transport rate was higher under the LC and +4 degrees C treatment, but the differences were not significant due to high variability in daily irradiances. Redundancy analysis on the data matrix for the light periods indicates that photosynthetically active radiation through the day is the main variable determining the physiological responses. The effects of nutrient levels (mainly carbon) and experimental increase of temperature were low but significant. During the night, the effect of nutrient availability is of special importance with an opposite effect of nitrogen compared to carbon increase. The application of the Monitoring-PAM to evaluate the effects of environmental conditions by simulating climate change variations under outdoor-controlled, semi-controlled conditions is discussed

Continuous monitoring of in vivo chlorophyll a fluorescence in ulva rigida (chlorophyta) submitted to different co2, nutrient and temperature regimes

A Monitoring-PAM fluorometer with high temporal resolution (every 5 min) was used to assess the effects on photosynthesis in Ulva rigida (Chlorophyta) during exposure to 2 different CO2 conditions: current (\u27LC\u27, 390 ppm), and the predicted level for the year 2100 (\u27HC\u27, 700 ppm) in a crossed combination with 2 different daily pulsed nitrate concentrations (\u27LN\u27, 5 mu M and \u27HN\u27, 50 mu M) and 2 temperature regimes (ambient and ambient +4 degrees C). Effective quantum yield (Delta F/F-m\u27) in the afternoon was lower under HCLN conditions than under the other treatments. The decrease in Delta F/F-m\u27 from noon to the afternoon was significantly lower under +4 degrees C compared to ambient temperature. Maximal quantum yield (F-v/F-m) decreased during the night with a transient increase 1 to 3 h after sunset, whereas a transient increase in Delta F/F-m\u27 was observed after sunrise. These transient increases have been related to activation/ deactivation of the electron transport rate and the relaxation of non-photochemical quenching. Relative electron transport rate was higher under the LC and +4 degrees C treatment, but the differences were not significant due to high variability in daily irradiances. Redundancy analysis on the data matrix for the light periods indicates that photosynthetically active radiation through the day is the main variable determining the physiological responses. The effects of nutrient levels (mainly carbon) and experimental increase of temperature were low but significant. During the night, the effect of nutrient availability is of special importance with an opposite effect of nitrogen compared to carbon increase. The application of the Monitoring-PAM to evaluate the effects of environmental conditions by simulating climate change variations under outdoor-controlled, semi-controlled conditions is discussed

Continuous monitoring of in vivo chlorophyll a fluorescence in Ulva rigida (Chlorophyta) submitted to different CO2, nutrient and temperature regimes

A Monitoring-PAM fluorometer with high temporal resolution (every 5 min) was used to assess the effects on photosynthesis in Ulva rigida (Chlorophyta) during exposure to 2 different CO2 conditions: current ('LC', 390 ppm), and the predicted level for the year 2100 ('HC', 700 ppm) in a crossed combination with 2 different daily pulsed nitrate concentrations ('LN', 5 mu M and 'HN', 50 mu M) and 2 temperature regimes (ambient and ambient +4 degrees C). Effective quantum yield (Delta F/F-m') in the afternoon was lower under HCLN conditions than under the other treatments. The decrease in Delta F/F-m' from noon to the afternoon was significantly lower under +4 degrees C compared to ambient temperature. Maximal quantum yield (F-v/F-m) decreased during the night with a transient increase 1 to 3 h after sunset, whereas a transient increase in Delta F/F-m' was observed after sunrise. These transient increases have been related to activation/ deactivation of the electron transport rate and the relaxation of non-photochemical quenching. Relative electron transport rate was higher under the LC and +4 degrees C treatment, but the differences were not significant due to high variability in daily irradiances. Redundancy analysis on the data matrix for the light periods indicates that photosynthetically active radiation through the day is the main variable determining the physiological responses. The effects of nutrient levels (mainly carbon) and experimental increase of temperature were low but significant. During the night, the effect of nutrient availability is of special importance with an opposite effect of nitrogen compared to carbon increase. The application of the Monitoring-PAM to evaluate the effects of environmental conditions by simulating climate change variations under outdoor-controlled, semi-controlled conditions is discussed