High spatial resolution photo mosaicking for the monitoring of coralligenous reefs

Coralligenous reefs are characterized by large bathymetric and spatial distribution, as well as heterogeneity; in shallow environments, they develop mainly on vertical and sub-vertical rocky walls. Mainly diver-based techniques are carried out to gain detailed information on such habitats. Here, we propose a non-destructive and multi-purpose photo mosaicking method to study and monitor coralligenous reefs developing on vertical walls. High-pixel resolution images using three different commercial cameras were acquired on a 10 m2 reef, to compare the effectiveness of photomosaic method to the traditional photoquadrats technique in quantifying the coralligenous assemblage. Results showed very high spatial resolution and accuracy among the photomosaic acquired with different cameras and no significant differences with photoquadrats in assessing the assemblage composition. Despite the large difference in costs of each recording apparatus, little differences emerged from the assemblage characterization: through the analysis of the three photomosaics twelve taxa/morphological categories covered 97–99% of the sampled surface. Photo mosaicking represents a low-cost method that minimizes the time spent underwater by divers and capable of providing new opportunities for further studies on shallow coralligenous reefs.

Mediating the Method

The scene is New York City, 1958. That year, in two disparate arenas, American culture was attempting to come to grips with the difference between noise and art. A twenty-five-year retrospective concert of John Cage's work at New York's Town Hall helped create an intellectually coherent canon out of Cage's experiments, which critics had often treated as puerile provocations or exercises in whimsy to be regarded with bemused toleration. For some forward thinkers, noise was becoming intellectually exciting material for experimental music, whereas the audible audience outrage preserved by the recording of the Town Hall concert testifies to the continuing rearguard pique of more conservative sensibilities. Cage himself couldn't have imagined a more apt illustration of his theories than this aleatory auditory event, preserved for posterity by the recording apparatus.

Multifocal visual-evoked potentials in patients with schizophrenia during treatment

Aim: Investigation of responses of multifocal visual-evoked potentials (mfVEPs) in schizophrenic patients under treatment in whom no abnormality was detected on the conventional perimetry.Methods: Recordings of mfVEPs were performed in 31 schizophrenic patients and 30 normal subjects using a VERIS Junior Science recording apparatus (Mayo, Aichi, Japan). Responses from eight sites in each subject were divided into four quadrants (superior and inferior temporal quadrants, and superior and inferior nasal quadrants). In each quadrant, two response waves were grouped and averaged, and the latency and amplitude of main waveforms that appeared near 100 ms were evaluated.Results: The peak latency was about 7–9 ms prolonged and the amplitude was reduced by about 2–5 nV/deg2 in the schizophrenic patient group compared to those in the normal subject group, and significant differences were noted in both parameters in all quadrants.Conclusion: In schizophrenic patients under treatment with psychotropic agents, prolongation of the latency and amplitude reduction were noted in mfVEPs even though no abnormality was detected on the conventional perimetry.

THE PARASITE PHENOMENON IN A TCAVE CANAL

A detailed study of wave profiles undertaken by our laboratory and making use of a wave recording apparatus, which is the subject of another paper, has drawn our attention to a parasite phenomenon. In certain conditions this phenomenon has a period twice that of the principal movement. The phenomenon appears only over a certain range of periods and has been shown to be the result of a transversal clapotis. The appearance of a transversal clapotis in wave canals is not rare and in practice it is eliminated by placing vertical guides parallel to the longitudinal axis of the canal. We have succeeded in eliminating the transversal clapotis reasonably well, by the use of wave filters. But a progressive phenomenon, with the period of the clapotis, has remained and it has been possible to analyse it.