Low-frequency fluctuations observed in the coherence collapse of semiconductor lasers are numerically investigated based on the Lang-Kobayashi model. It is found that the attractor in the compound cavity mode loses its stability due to a crisis with an antimode. Chaotic itinerancy among the destabilized compound cavity modes is also found.PACS number(s): 42.50. Ne, 42.55.Px, 42.60.Mi, 05.45.+b

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Herbicides containing glufosinate ammonium are widely used in many countries including Japan. Many Japanese cases of accidental and suicidal poisoning by glufosinate have been reported since 1989. We report a case of a 64- year old man who ingested glufosinate in an attempted suicide. The patient suffered mental disturbances and hematological changes together with gastrointestinal effects shortly after ingesting the poison, and later developed generalized convulsions, impaired respiration and circulatory failure. During recovery he exhibited loss of short-term memory (retrograde and anterograde amnesia). Neurotoxicity is a characteristic of glufosinate poisoning, although the mechanism is not clear. From the analysis of clinical symptoms of previously published cases, glufosinate toxicity appears to arise both from the active ingredient and the surfactant in the formulation.

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InAs quantum dots (QDs) with an ultrahigh density of 1 ' 10 12 cm %2 were fabricated on a 1.25-monolayer-thick InAsSb wetting layer on a GaAs(001) substrate by molecular beam epitaxy. QD formation was initiated by small two-dimensional InAsSb islands. Coalescence and ripening effects involving neighboring QDs were suppressed. Photoluminescence spectra of the QDs shifted continuously to higher energies with increased optical excitation power. This was attributed to the filling of inhomogeneous ground states via tunneling between QDs. Indirect transitions in a type-II band structure were observed for small QDs. In large QDs, direct transitions were also observed at high optical excitation levels.