A sodium lidar at Syowa station (69°S, 39°E), Antarctica, measured temperature profiles from 80 to 110 km between March and September during 2000 and 2001. Monthly averaged temperature profiles in the mesopause region in wintertime (June, July and August) are nearly 20 K lower than those in the northern hemisphere sites. The measured winter mesopause altitudes (∼99 km) are in good agreement with those measured at Fort Collins (41°N) and Andøya (69°N) in winter. The mesopause temperatures (∼175 K) in winter months however are about 20 K lower than those observed from a northern hemisphere conjugate site, Andøya. The lower winter mesopause temperatures measured at Syowa station, which are consistent with southern hemisphere mesopause temperatures measured by a shipborne lidar, suggest the existence of a hemispheric difference. Possible causes for this difference are discussed.

A mobile laser-induced fluorescence spectrum (LIFS) lidar was developed for monitoring pollens floating in the atmosphere. The fluorescence spectrum of pollens excited at 355 nm was measured with a fluorescence spectrometer and the results suggested that in general they had peaks at around 460 nm and the ranges were 400–600 nm. A fluorescence spectrum database of 25 different pollens was made with the 355 nm excitation. Based on these results, we developed a LIFS lidar that had features in pollen species identification and daytime operation. The former was achieved by the database and the latter was possible by introducing a synchronous-delay detection to a gated CCD spectrometer in an operation time of 200 ns. Fluorescence detection of pollens floating in the atmosphere was performed using the LIFS lidar in a field where cedars grow in the spring and ragweed in the autumn. The LIFS lidar system successfully detected fluorescence spectrums of the pollens at a distance of approximately 20 m away. We discussed the performance of the LIFS lidar by estimating the number of cedar pollens using a lidar equation, introducing a fluorescence cross section of cedar pollens and a sensitivity of the CCD spectrometer that was measured by ourselves.

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We developed a UV (355 nm) laser-induced fluorescence (LIF) lidar for monitoring the real-time status of blue-green algae. Since the fluorescence spectrum of blue-green algae excited by 355 nm showed the specific fluorescence at 650 nm, the lidar was designed to be able to detect the 650 nm fluorescence as a surveillance method for the algae. The usefulness was confirmed by observation at Lake Suwa over four years (2005-2008). The detection limit of the LIF lidar was 16.65 mg/L for the blue-green algae, which is the range of concentrations in the safe level set by the World Health Organization.

Key points• The ON and OFF channels are basic functional elements in parallel processing in the visual system in vertebrates including primates, and ON cells excite by positive contrasts, while OFF cells excite by negative contrasts.• We investigated the electrophysiological properties of optic tract fibre activities in neurosurgical patients with Parkinson's disease, focusing on ON-and OFF-type responses to flashlight stimulation.• Most of the multi-fibre responses at the light on event were excitatory, and excitatory responses at the light off event were observed at a few sites. Analysis of the single-fiber responses revealed ON fibres and OFF fibres.• All excitatory responses to light on were transient, while all but one excitatory responses to light off were sustained. These different response types are said to contain different modes of visual information.• Our results demonstrate for the first time the ON and OFF channels and their temporal features in visual processing in humans.Abstract The ON and OFF channels are basic functional elements in parallel processing in the visual system in vertebrates including primates. We analysed the responses of the optic tract fibre activity in response to switching a flashlight on or off in 25 awake patients with Parkinson's disease who underwent stereotactic surgery targeting the internal globus pallidus. The responses were evoked in a darkened room by a light with a luminance of approximately 4 × 10 4 cd m −2at the eye and a wide-spectrum wavelength. Most of the responses at the light on event were excitatory (38 out of 41 sites, 93%). Thirty-five sites with increase in activity at the light on event showed reciprocal responses or no responses to light off, and these sites were classified as containing ON fibres. In single-fibre analysis, all of 14 ON fibres were recorded at the sites of multi-fibre excitatory responses. Six sites showed multi-fibre excitatory responses at the light off event; three sites showed sustained reduction in activity at the light on event, and these three sites were classified as containing OFF fibres. In single-fibre analysis, two OFF fibres were recorded at the sites of multi-fibre suppressive responses at the light on event, and the other two OFF fibres were recorded at the sites of multi-fibre excitatory responses at the light on event. We found that all excitatory responses to light on were transient, while all but one excitatory responses to light off were sustained. Reduction in activity tended to be smaller than increase in activity at the light on event. These results demonstrate that the ON and OFF channels, and their transient and sustained features function in visual processing in humans. Abbreviations CT, computed tomography; GPi, internal segment of globus pallidus; MRI, magnetic resonance imaging; OT, optic tract.