Perspectives of 2D and 3D mapping of atmospheric pollutants over urban areas by means of airborne DOAS spectrometers

tants, offering numerous advantages over conventional networks of in situ analysers. We propose some innovative solutions in the field of DOAS (Differential Optical Absorption Spectroscopy) remote systems, utilizing diffuse solar light as the radiation source. We examine the numerous potentialities of minor gas slant column calculations, applying the «off-axis» methodology for collecting the diffuse solar radiation. One of these particular approaches, using measurements along horizontal paths, has already been tested with the spectrometer installed on board the Geophysica aircraft during stratospheric flights up to altitudes of 20 km. The theoretical basis of these new measurement techniques using DOAS remote sensing systems are delineated to assess whether low altitude flights can provide 2D and 3D pollution tomography over metropolitan areas. The 2D or 3D trace gas total column mapping could be used to investigate: i) transport and dispersion phenomena of air pollution, ii) photochemical process rates, iii) gas plume tomography, iv) minor gas vertical profiles into the Planetary Boundary Layer and v) minor gas flux divergence over a large area

The anatomy and physiology of the optic nerve: historical notes.

Abstract The authors outline the historical development of anatomical and physiological acquisitions on the optic nerve. From the first descriptions of Alcmaeone of Crotone (6th century B.C.) through the Aristotelean school, we arrive at the systemization of Claudius Galen. After the medioeval parenthesis, it fell to Vesalius to give a new impulse to anatomical research. Varolio and Eustachi describe the exact point of origin of the optic nerves. Later observations involve both anatomists and physiologists. The question of the transmission of sensory messages is described (Willis, von Haller), as is the microscopic structure of the optic nerve (Zinn, von Leeuwenhoek). After the description of the decussation of the fibers of the optic nerve in the optic chiasma, research into this cranial nerve has an increasingly neurophysiological and neurochemical orientation, continuing until the recent discovery of axoplasmic flow