The prevalence of preferential nasal breathing in adults

The prevalence of preferential nasal breathing was studied in an awake adult population. One hundred and ninety-four people consented to gentle manual compression of the nostrils. They were advised to 'breathe in and out', but no further information regarding breathing was given to avoid influencing the patient. One hundred and eighty patients (92.8%) commenced immediate regular relaxed breathing. Fourteen patients (7.2%) had difficulty with oral breathing which ranged from irregular mouth breathing associated with distress to no spontaneous respiration. The prevalence of preferential nasal breathing was strongly associated with increasing age (chi 2 for trend, P = 0.007). In addition, a weakly significant association was demonstrated between a history of asthma and this phenomenon (P = 0.047). These findings suggest a tendency for the elderly person to revert to the infant pattern of obligate nasal breathing. Physicians should be aware of this possibility in the elderly patient, especially prior to any procedure which may induce nasal obstruction.     

A noise resistant synchronization scheme for HDTV images

A method that increases the error resistance of the HDTV system and offers graceful picture degradation in the presence of bit errors, is presented. Due to the nature of the presently proposed compression schemes for HDTV systems, an error in a data bit does not only affect the block the bit belongs to, but unfortunately the effects of this error may perpetuate to the following blocks. This is because a bit error may cause loss of synchronization between the data bits and the picture blocks they represent. Our method restricts the effects of a bit error to a picture block whose size is significantly smaller than those used by the HDTV systems. We achieve synchronization by transmitting a header-word for each such synchronization block. Each header-word contains the number of data bits representing the compressed block. This header-word is protected by two levels of FEC code. To decrease the number of extra bits needed by the header-words, two different synchronization block sizes are used, a relatively small block size for the reference frames and a larger size for the inter-frames. The resulting method improves the quality of the picture in the presence of errors and defers the SNR at which the HDTV picture suddenly deteriorates by 2.5 to 3 dB. It also allows operation at higher order modulation transmission schemes, e.g., 32-QAM instead of 16-QAM, without the requirement of increased signal power     

A Method for Measuring Pulsed Amplifier Noise Using a Spectrum Analyzer

Measuring the noise generated by a pulsed RF amplifier is not a simple task [1]. One method of making this measurement converts the RF pulse to video with a phase detector and uses a spectrum analyzer to measure the noise between the lines of the pulse spectrum. The measurement includes the combined effects of timing jitter, power-supply modulation, and amplifier noise. An alternate method, described in this note, requires less test equipment by using an RF spectrum analyzer to measure the noise at a point outside the pulse spectrum. This measurement responds only to amplifier noise and is valid if the noise density is the same both inside and outside the pulse spectrum. Since this situation tends to be true of broad-band amplifiers such as TWT's and CFA's, the second method is preferable because of its relative simplicity. This note describes the procedure for measuring pulsed amplifier noise using an RF spectrum analyzer. The test setup and measurement procedure are described, as well as the conversion of the measured spectral-density ratio to an equivalent CW signal-to-noise ratio.     

A connectionist implementation of the theory of planned behavior: Association of beliefs with exercise intention.

The theory of planned behavior suggests attitudes are a product of salient beliefs. This study examined whether aggregating salient beliefs was plausible within a more biologically centered information-processing environment. A neural network was used to examine associations among beliefs relating to exercise intention. Data on intentions and behavioral, normative, and control beliefs from 114 respondents were used to train (by error backpropagation) a neural network to associate beliefs with intention. The R2 between the network's estimated and self-reported intention was .66. The network's representation comprised 6 belief profiles associated with high, moderate, or low behavioral intention. The neural network accommodated complex relationships among beliefs and belief-intention associations and indicated how high-level constructs such as attitudes may be viewed as the best fit (compromise state) between aroused beliefs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of linguistic structure on children's ability to isolate initial consonants.

In 4 experiments, preschoolers and kindergartners were asked to pronounce the initial consonants of spoken words. Children performed better on short words, such as bay, than on long words, such as bonus. Words with initial consonant clusters, such as brow, were more difficult for the children than words without initial consonant clusters, such as bar. A consonant cluster at the end of the word did not harm performance. Children did relatively well on words like suppose, for which the word's 1st syllable, /s/, constitutes a correct answer on the initial consonant isolation task. Children did more poorly on words like satin, for which this was not the case. Thus, the linguistic structure of a word affects children's ability to isolate the initial consonant. Implications for the design of phonemic awareness instruction are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Device to Provide Respiratory-Mechanical Unloading

A commercially available and widely used servo-controlled ventilator has been modified to provide controlled inspiratory resistive unloading of the human respiratory system. This is achieved by establishing a positive mouth pressure throughout inspiration in a constant proportion to instantaneous flow, i.e., the ratio of mouth pressure to flow, which defines the "assistance," remaining constant. The performance of this device has been evaluated in four healthy subjects during steady-state, constant-load cycling (20-120 W). It is demonstrated that i) the device can successfully implement controlled degrees of inspiratory assistance on a breath-to-breath basis; ii) the assistance can be sustained over a substantial range of ventilatory drive (i.e., for ventilations up to some 30 1/min) and to an extent which approaches a 100 percent reduction of the normal respiratory resistance. This device should prove useful in experimental and clinical investigations of the respiratory responses to resistive unloading of the respiratory system.     

Aging and prospective memory: Examining the influences of self-initiated retrieval processes.

Past research has frequently failed to find age differences in prospective memory. This article tested the possibility that age differences would be more likely to emerge on a prospective memory task that was high in self-initiated retrieval. In the 1st experiment, participants were asked to perform an action every 10 min (a time-based task presumed to be high in self-initiated retrieval); in the 2nd experiment, participants were asked to perform an action whenever a particular word was presented (an event-based task presumed to be relatively low in self-initiated retrieval). Age differences were found with the time-based task but not with the event-based task. This pattern of age differences was again found in a 3rd experiment in which a new experimental procedure was used and the nature of the prospective memory task was directly varied. Generally, the results suggest that self-initiated retrieval processes are an important component of age-related differences across both retrospective and prospective memory tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)