Long-term effects of carbon monoxide poisoning at Miike coal mine: A 33-year follow-up study.

On November 9, 1963, a coal dust explosion occurred at the Miike Mikawa Coal Mine (Omuta, Kyushu Region of Japan). This resulted in a massive release of carbon monoxide (CO) gas that resulted in 458 fatalities and 839 victims of CO poisoning. After the accident, the Department of Neuropsychiatry, Kumamoto University School of Medicine (including the authors) immediately began to conduct periodic medical examinations of the victims. Such a long-term follow up of so many CO-poisoned patients is globally unprecedented. When the Miike Mine was closed in March of 1997, 33 years after the disaster, we conducted the final follow-up study.

Kerr-lens mode-locked Tm3+:Sc2O3 single-crystal laser in-band pumped by an Er:Yb fiber MOPA at 1611 nm.

We demonstrate a Kerr-lens mode-locked Tm3+:Sc2O3 single-crystal laser in-band pumped by an Er3+:Yb3+ fiber master oscillator power amplifier at 1611 nm. Pulses as short as 166 fs with an average output power of 440 mW are obtained. The spectral bandwidth and center wavelength are 29.3 and 2124 nm, respectively. At a longer pulse duration of 298 fs, we obtain 1 W of average output power. The repetition rate is 95 MHz, and the conversion efficiency against the absorbed pump power is as high as 47%. To the best of our knowledge, this is the first Kerr-lens mode-locked Tm3+-doped solid state laser.

Tunable noise-like pulse generation in mode-locked Tm fiber laser with a SESAM.

We report on a tunable noise-like pulse (NLP) generation in a mode-locked Tm fiber laser with a SESAM. A tuning range of 1895-1942 nm, while keeping the spectral bandwidth of 10-19 nm under NLP mode-locked operation, was obtained by a tunable filter based on chromatic dispersion of telescope lenses. At the center wavelength of 1928 nm, the maximum output power of 195 mW with the spectral bandwidth of 18.9 nm was obtained. The repetition rate was 20.5 MHz and the corresponding pulse energy was 9.5 nJ. To our knowledge, this is the first report of a tunable NLP mode-locked laser based on chromatic dispersion of a lens system.

High power narrow-linewidth linearly-polarized 1610 nm Er:Yb all-fiber MOPA.

We developed a narrow-linewidth linearly-polarized all-PM-fiber MOPA at the wavelength of 1610 nm. The MOPA consists of a DFB laser diode seed source and three amplifier stages with three different gain fibers. The first amplifier stage employed an Er doped fiber and the second and third amplifier stages employed Er:Yb co-doped fibers. The maximum output power was 8 W. Linewidth of 25 MHz and polarization extinction ratio of 28 dB was obtained. At the maximum output power, no ASE component around 1.55 µm or 1µm was observed.

Increment in the volcanic unrest and number of eruptions after the 2012 large earthquakes sequence in Central America.

Understanding the relationship cause/effect between tectonic earthquakes and volcanic eruptions is a striking topic in Earth Sciences. Volcanoes erupt with variable reaction times as a consequence of the impact of seismic waves (i.e. dynamic stress) and changes in the stress field (i.e. static stress). In 2012, three large (Mw ≥ 7.3) subduction earthquakes struck Central America within a period of 10 weeks; subsequently, some volcanoes in the region erupted a few days after, while others took months or even years to erupt. Here, we show that these three earthquakes contributed to the increase in the number of volcanic eruptions during the 7 years that followed these seismic events. We found that only those volcanoes that were already in a critical state of unrest eventually erupted, which indicates that the earthquakes only prompted the eruptions. Therefore, we recommend the permanent monitoring of active volcanoes to reveal which are more susceptible to culminate into eruption in the aftermath of the next large-magnitude earthquake hits a region.

Gas flux cyclic regime at an open vent magmatic column inferred from seismic and acoustic records.

On August 7, 2014, a new effusive vent opened on the northern flank of Stromboli. A characteristic pattern was observed in both seismic and infrasonic signal amplitudes prior to this effusive eruption. The pattern consisted of the repeating cycle: (1) quiet phase, (2) puffing phase, and (3) explosion phase. Correlation between seismic and infrasound signal suggests that pulses in the puffing phase were caused by repetitive bursts of small gas pockets at the central crater, while the explosion phase coincided with an explosion at the central crater. We show that degassing of the magma column occurred in cycles of increasing gas flux, which controlled the transition from a bubbly flow (puffing phase), to a slug flow (explosion phase) gas regime. The quiet phase was characterized by a constant time length of 150 s, indicating that the gas rose in the magma column as well-organized waves of gas layers. These cycles represent cyclic changes of the gas flux regime in the shallow magma column, associated with increases in the magma-gas supply input rate before the effusive eruption.