How does the pitch and pattern of a signal affect auditory arousal thresholds?

How arousal thresholds vary with different sounds is a critical issue for emergency awakenings, especially as sleepers are dying in fires despite having a working smoke alarm. Previous research shows that the current high-pitched (3000+ Hz) smoke alarm signal is significantly less effective than an alternative signal, the 520 Hz square wave, in all populations tested. However, as the number of sounds tested has been small further research is needed. Here we measured auditory arousal thresholds (AATs) across signals with a range of characteristics to determine the most effective waking signal. Thirty-nine young adults participated over three nights. In Part A, nine signals were presented in stage 4 sleep with ascending decibel levels. Signals were short beeps in the low- to mid-frequency range with different spectral complexities: square waves, pure tones, whoops and white noise. Part B manipulated temporal patterns, inserting silences of 0, 10 and 21 s after each 12 s of beeps. It was found that the low-frequency (400 and 520 Hz) square waves yielded significantly lower AATs than the alternatives. A trend was found across the three temporal manipulations, with a 10 s intervening silence showing some advantage. These findings support earlier research indicating that the best sound for awakening from deep sleep is a low-frequency square wave. It is argued that the signal with the lowest response threshold when awake may be the same as the most arousing signal when asleep, especially where the sleeper processes the signal as meaningful.     

The relationship between structural empowerment and psychological empowerment for nurses: a systematic review

wagner j.i.j., cummings g., smith d.l., olson j., anderson l. & warren s. (2010) Journal of Nursing Management 18 , 448–462
The relationship between structural empowerment and psychological empowerment for nurses: a systematic review Aim To describe the findings of a systematic review examining the relationship between structural empowerment and psychological empowerment for registered nurses (RNs). Background Workplace empowerment research reveals a link between empowerment and positive work behaviours and attitudes. Research demonstrating the essential relationship between structural empowerment and psychological empowerment will provide direction for future interventions aimed at the development of a strong and effective health care sector. Methods Published research articles examining structural empowerment and psychological empowerment for nurses were selected from computerized databases and selected websites. Data extraction and methodological quality assessment were completed for the included research articles. Results Ten papers representing six studies reveal significant associations between structural empowerment and psychological empowerment for RNs. Implications for nursing management Creation of an environment that provides structural empowerment is an important organizational strategy that contributes to RNs’ psychological empowerment and ultimately leads to positive work behaviours and attitudes. Critical structural components of an empowered workplace can contribute to a healthy, productive and innovative RN workforce with increased job satisfaction and retention.     

Fetal Arrhythmias: A 3-Year Experience*

Eight cases of fetal arrhythmia were seen over a 3-year period. Two had atrial and/or ventricular extrasystoles, 1 had complete atrioventricular block and 5 had tachyarrhythmias--3 supraventricular tachycardia, 1 atrial flutter and 1 ectopic atrial tachycardia. All had structurally normal hearts. Nonimmune hydrops fetalis was the initial presentation in 3 of the 5 cases with tachyarrhythmias. There were 2 deaths--a stillbirth and a neonatal death, while 2 others required neonatal intensive care. The 6 survivors have remained well and are now off treatment. The diagnosis, careful assessment and management of a fetal arrhythmia may lead to a successful outcome. The complexity of the problems experienced may warrant early referral to a tertiary centre where the overall management of the mother, fetus and neonate, may be undertaken.