Tone burst-evoked otoacoustic emissions in neonates: normative data

<p>Abstract</p> <p>Background</p> <p>Tone-burst otoacoustic emissions (TBOAEs) have not been routinely studied in pediatric populations, although tone burst stimuli have greater frequency specificity compared with click sound stimuli. The present study aimed (1) to determine an appropriate stimulus level for neonatal TBOAE measurements when the stimulus center frequency was 1 kHz, (2) to explore the characteristics of 1 kHz TBOAEs in a neonatal population.</p> <p>Methods</p> <p>A total of 395 normal neonates (745 ears) were recruited. The study consisted of two parts, reflecting the two study aims. Part I included 40 normal neonatal ears, and TBOAE measurement was performed at five stimulus levels in the range 60–80 dB peSPL, with 5 dB incremental steps. Part II investigated the characteristics of the 1 kHz TBOAE response in a large group of 705 neonatal ears, and provided clinical reference criteria based on these characteristics.</p> <p>Results</p> <p>The study provided a series of reference parameters for 1 kHz TBOAE measurement in neonates. Based on the results, a suggested stimulus level and reference criteria for 1 kHz TBOAE measures with neonates were established. In addition, time-frequency analysis of the data gave new insight into the energy distribution of the neonatal TBOAE response.</p> <p>Conclusion</p> <p>TBOAE measures may be a useful method for investigating cochlear function at specific frequency ranges in neonates. However, further studies of both TBOAE time-frequency analysis and measurements in newborns are needed.</p

Therapeutic Radionuclides: Making the Right Choice

Recently, there has been a resurgence of interest in nuclear medicine therapeutic procedures. Using unsealed sources for therapy is not a new concept; it has been around since the beginnings of nuclear medicine. Treatment of thyroid disorders with radioiodine is a classic example. The availability of radionuclides with suitable therapeutic properties for specific applications, as well as methods for their selective targeting to diseased tissue have, however, remained the main obstacles for therapy to assume a more widespread role in nuclear medicine. Nonetheless, a number of new techniques that have recently emerged, (e.g., tumor therapy with radiolabeled monoclonal antibodies, treatment of metastatic bone pain, etc.) appear to have provided a substantial impetus to research on production of new therapeutic radionuclides. Although there are a number of new therapeutic approaches requiring specific radionuclides, only selected broad areas will be used as examples in this article

The Coyote-Proof Pasture Experiment

Few scientific experiments have influenced more land than one conducted in the Wallowa Mountains of eastern Oregon by the US Department of Agriculture’s Bureau of Plant Industry and US Forest Service in 1907–1909. Four square miles of land were enclosed with a “coyote-proof fence,” guarded by a hunter, and stocked with an untended band of sheep. Data were collected on vegetation and sheep performance inside and outside the fence, and two years later success was declared. By 1910, the Forest Service had wrested range research from the Bureau of Plant Industry, subordinating the emerging field to timber production and fire suppression for decades to come. The young scientist who conducted the experiment, James Jardine, was promoted to Inspector of Grazing for the fledgling Forest Service, while his Wallowa collaborator, Arthur Sampson, went on to become “the father” of range science. The model of range management that they pioneered was applied across the US West and, later, on many rangelands in the developing world. Fencing and predator control are now generally viewed as unrelated management practices, but in the Forest Service model they were intimately connected. A critical physical geography of the Wallowa experiment reveals that the institutional context in which it occurred was more important than the findings themselves, and that although the results appeared to be scientifically rigorous and ecological, the methods were weak and the real criteria for “success” were economic. The high costs of fencing could be justified only if they were offset by a reduction in labor costs for herders. But without herders to guard the livestock, predators would have to be eliminated. Enormous public subsidies were required to implement the model, which continues to affect rangelands around the world