Operant Procedures in the Auditory Assessment of "Difficult-To-Test" Individuals

33 leaves. Advisor: Larry A. AlferinkThe Problem. Standard audiometric assessment procedures are not effective in testing some mentally retarded individuals for sensory capabilities. The present study investigated the use of operant conditioning procedures to determine hearing threshold levels with profoundly retarded individuals. Procedure. Three profoundly retarded individuals were trained to respond on an FR 2 or 3 schedule of reinforcement to puretone presentations of several frequencies (500,1000, 2000, and 4000 Hz). Then, hearing thresholds were determined for each subject using two types of threshold tests, the descending-series method and a trials-wise tracking procedure, the staircase method. The order of threshold test administration was counterbalanced across subjects. Findings. Reliable hearing threshold levels were obtained within subjects and within the type of threshold test employed. All subjects were observed to "track" their own threshold levels with the staircase procedure, and the obtained threshold levels were similar to or lower than those produoed with the descending-series method. Conclusions. The systematic employment of operant conditioning procedures enabled the production of hearing thresholds with "difficult-to-test", profoundly retarded individuals. A trials-wise tracking procedure, or staircase method, proved to be very functional in the determination of sensory capabilities with such individuals. Recommendations. In order to assess the auditory capabilities of "difficult-to-test" individuals, the clinical investiqator should (1) employ operant conditioning training procedures to ensure increased control of the subject's behavior in the clinical situation, and (2) use testing procedures which allow for the attainment of both reliable and valid sensory profiles

Electromagnetic corrections for the analysis of low energy pi-p scattering data

We calculate the electromagnetic corrections to the isospin invariant mixing angle and to the two eigenphases for the s and p-waves for low energy pi-p elastic and charge exchange scattering. These corrections have to be applied to the nuclear quantities obtained from phase shift analyses of the experimental data in order to obtain the hadronic phases. We compare our results with earlier calculations and estimate the uncertainties in the corrections.Comment: 19 pages, 5 figures. Uses elsart.cls Accepted for publication in Nuclear Physics

Drosophila bloom helicase maintains genome integrity by inhibiting recombination between divergent DNA sequences

DNA double strand breaks (DSB) can be repaired either via a sequence independent joining of DNA ends or via homologous recombination. We established a detection system in D. melanogaster to investigate the impact of sequence constraints on the usage of the homology based DSB repair via single strand annealing (SSA), which leads to recombination between direct repeats with concomitant loss of one repeat copy. First of all, we find the SSA frequency to be inversely proportional to the spacer length between the repeats, for spacers up to 2.4 kb in length. We further show that SSA between divergent repeats (homeologous SSA) is suppressed in cell cultures and in vivo in a sensitive manner, recognizing sequence divergences smaller than 0.5%. Finally, we demonstrate that the suppression of homeologous SSA depends on the Bloom helicase (Blm), encoded by the Drosophila gene mus309. Suppression of homeologous recombination is a novel function of Blm in ensuring genomic integrity, not described to date in mammalian systems. Unexpectedly, distinct from its function in S. cerevisiae, the mismatch repair (MMR) factor Msh2 encoded by spel1 does not suppress homeologous SSA in Drosophil

Ανάδειξη της αγροτικής παραγωγής στην αστική καθημερινότητα. _προβολή _ εμπόριο _ ενημέρωση στην Θήβα

An 'aggregate economic' value (H), which is a combination of genetic control and relative economic value of traits, for all traits in the breeding objective was developed to aid in multitrait selection of strawberry cultivars in the subtropical southeast Queensland program. A profitability index for 12 traits was calculated from the effect of unit changes in each trait on changes in production costs and profitability. The index was applied to the breeding values of 3008 genotypes to produce estimates of H. H was validated by its high correlation (R=0.77) with year of selection (1945-1998) for commercial cultivars. H values for 3008 genotypes ranged from -0.36 to +0.28, when the zero value was set to the value of the cultivar 'Festival', which is the main cultivar grown in southeast Queensland. Modelling indicated that the gross margins were highly linearly related (R0.98) to H values where the genotype occupied less than 50% of total area planted in the industry, but this relationship became quadratic when the genotype occupied higher percentages of the total area planted to strawberries, and variation in gross margin increased as H values increased. H is efficient in identifying economically superior genotypes, but, when deploying new genotypes with high H, impacts on farm gross margin due to high adoption rates should also be considered