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Abstract: Larissa, the capital of Thessaly, is located in the eastern part of Central Greece, at the southern border of a Late Quarternary graben, the Tyrnavos Basin. Palaeoseismological, morphotectonic, and geophysical investigations as well as historical and instrumental records show evidences for seismic activity in this area. Previous investigations documented the occurrence of several moderate to strong earthquakes during Holocene time on active faults with recurrence intervals of a few thousand years. The historical and instrumental records suggest a period of seismic quiescence during the last 400–500 years. The present archaeoseismological research, based on a multidisciplinary approach is devoted to improve the knowledge on past earthquakes, which occurred in the area. This study focuses on damages observed on the walls of the scene building of the Great Theatre of Larissa. The Theatre was built at the beginning of the third century BC and consists of a semicircular auditorium, an almost circular arena and a main scene building. Archaeological and historical investigations document a partial destruction of the theatre during the second to first century BC. Recent excavations show that the building complex after it was repaired suffered additional structural damages, probably from seismic loading. The damages investigated in detail are displacements, rotations and ruptures of numerous blocks at the walls of the scene building. In order to test the earthquake hypothesis as cause of the damages a simplified seismotectonic model of the Tyrnavos Basin and its surroundings was used with a composite earthquake source model to calculate synthetic seismograms at the Larissa site for various earthquake scenarios. Horizontal to vertical seismic ratio (HVSR) measurements in the theatre and its vicinity were used to estimate local site effects. The synthetic seismograms are then used as input accelerations for a finite element model of the walls, which simulates seismically induced in-plane sliding within the walls. Results show that some of the surrounding faults have the potential to produce seismic ground motion that can induce in-plane sliding of blocks. Model calculations were used to constrain the characteristics of the ground acceleration and infer the causative fault and earthquake by comparing the calculated and observed distribution of the displacements of the blocks. Ground motions with a PGA at the site of 0.62–0.82 g, which could be induced by an M 5.8–6.0 earthquake on the nearby Larissa Fault, would be sufficient to explain the damage.

Detection of anti-HIV-1 IgA antibodies using a modified ELISA test for the early diagnosis of perinatally acquired HIV-1 infection in children treated with protocol ACTG 076 was evaluated. A total of 177 sera were obtained from 141 infants between 1 and 12 months of age (46 were treated and 95 were non-treated with protocol ACTG 076) and tested for HIV IgA antibodies by an ELISA test after removal of IgG with recombinant protein G. Infants were classified according to CDC's classification system after a follow-up until 20 months of age. Of the 46 treated children 22 turned out to be infected and in the group of 95 untreated children, 52 were infected. All 81 samples from uninfected children treated or untreated with protocol ACTG 076 were persistently IgA-negative. HIV IgA antibodies were detected in 14 of 25 plasma samples from infected children with treatment, and in 58 of 71 samples in infected children without treatment. Considering that the sensitivity of this test is lower in children younger than 6 months the population of children studied was divided into two groups; those under and those over 6 months of age. No significant differences were observed in the detection of IgA in treated or untreated children in both age groups. The overall specificity of the test was 100 per cent; sensitivity in children older than 6 months was 76.92 per cent in treated children and 93.10 per cent in untreated children. In spite of the small number of samples studied it could be demonstrated that treatment with zidovudine does not affect the detection of IgA antibodies. This is a simple and inexpensive method that could be used for diagnosis of treated and untreated children in developing countries.