The effect of low flow oxygen on sleep-disordered breathing and oxygen desaturation. A study of patients with chronic obstructive lung disease

Oxygen desaturation occurs during sleep in many patients with chronic obstructive lung disease (COLD) and is often caused by sleep-disordered breathing (SDB). Nocturnal oxygen therapy should improve nighttime hypoxemia, but might also worsen SDB. Using standard polysomnographic techniques, we evaluated the frequency and duration of oxygen desaturation and SDB during sleep in 11 patients with stable COLD. During half of the night the patients breathed air through a nasal cannula and during the other half of the night they breathed oxygen at 2 liters per minute. Five patients had arterial lines inserted for determination of arterial blood gas levels during periods of SDB or desaturation. The ten men and one woman slept 70 minutes (52 percent of time in bed) while on air and 111 minutes (80 percent of time in bed) while on oxygen (p < 0.001). Oxygen therapy reduced the number of episodes of desaturation per hour and the time spent in desaturation. However, there was no difference between air and oxygen in episodes of SDB per hour, the duration of episodes of SDB, baseline sleeping PaCO2 or PaCO2 during episodes of desaturation or SDB. Therefore, in most patients with stable COLD, administration of oxygen at 2 liters per minute improves oxygenation, prolongs sleep, but does not adversely affect SDB.     

Silicone-polyethylene blends

Polyethylene and reactive, high molecular weight polydimethylsiloxanes have been blended under conditions of shear and elevated temperature in order to form uniform, thermoplastic blends. The materials can be extruded, coated on wire, injection molded, or compression molded. Despite the thermoplastic nature, a high gel fraction is present. A structure is proposed consisting of microgelled and grafted particles of silicone dispersed in polyethylene. When compared to pure polyethylene, the blends show lowered modulus over a temperature range of ?150 to +65°C increased gas permeability, and lowered mixing energies. Electrical properties include corona resistance superior to polyethylene and a resistance to degradation under conditions simulating those experienced by buried cables superior to typical silicone rubber. Other electrical properties are intermediate between the values observed in the component polymers.     

L-Orthogonal Signal Transmission and Detection

This paper investigates the detail capabilities and performance characterization of systems that employL-orthogonal signaling techniques.L-orthogonal signals represent a unified set of signals wherein the polyphase and orthogonal (biorthogonal) signal sets are included as special cases. This fact is important since orthogonal (biorthogonal) and polyphase signaling sets represent opposing forces as far as tradeoffs between error probability, energy-to-noise ratio, and bandwidth requirements are concerned. Bounds on the performance of the optimum receiver and the performance of various suboptimum (practical) receiver structures are given. Coherent and differentially encoded signals are also pursued. Various comparisons and tradeoffs are made by means of numerical evaluation of the error-probability expressions.     

Acquisition Behavior of a First-Order Digital Phase-Locked Loop

A general "phase-plane" technique for investigating the stability of nonlinear difference equation is described and applied to determine the stability criterion of a first-order digital phase-locked loop (DPLL). If the loop is stable, it is shown that acquisition behavior can be modeled as a first passage time problem. Using this model, one can evaluate the acquisition probability and the mean time to acquire, from the appropriate Chapman-Kolmogorov (C-K) equation describing the transition of the phase error sequence. This approach is verified by direct simulation.     

The role of environmental ammonia in respiratory mycoplasmosis of rats

Young adult, pathogen-free rats of Sherman and Fischer (F344) substrains were inoculated intranasally with 10(8) colony-forming units (GFU) of M. pulmonis and housed for 4 to 6 weeks in environments with ammonia maintained at specific concentrations from 25 to 250 ppm. All levels of NH3--whether produced naturally from soiled bedding or derived from a purified source--significantly increased the severity of the rhinitis, otitis media, tracheitis, and pneumonia (including bronchiectasis) characteristic of murine respiratory mycoplasmosis (MRM). The prevalence of pneumonia, but not that of other respiratory lesions of MRM, showed a strong tendency to increase directly with environmental NH3 concentration. In contrast, NH3 exposure of rats not infected with M. pulmonis caused anatomic lesions that were unlike those of MRM and were limited to the nasal passages. It was concluded that environmental NH3, at concentrations commonly encountered in present day cage environments for rats, plays an important role in pathogenesis of MRM.     

The influence of associability changes in negative patterning and other discriminations.

Normal rats showed faster learning of a serial negative patterning (NP) discrimination (X+, A+, X→ A–) than of a comparable feature negative (FN) discrimination (A+, X→ A–). This advantage was absent in rats with lesions of the amygdala central nucleus. Earlier data indicated that this brain lesion interferes with surprise-induced increases in attention specified by the Pearce-Hall model (J. M. Pearce & G. Hall, 1980). In the NP task, but not the IN task, omission of the reinforcer after X on X→ A– trials was surprising. A variation of the NP task (NPX), in which X was reinforced on both X+ and X→ A–trials, was learned more rapidly than the NP task. Lesioned rats were unimpaired in learning the NPX task. Evaluation of the lesion effects and the results of postraining transfer tests suggested that the NP advantage involved attentional processes, whereas the NPX advantage was based on the acquisition of inhibitory control by aspects of excitation conditioned to X. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hydrothermal carbonization of distiller’s grains

Wet distiller’s grains are intermediate byproducts of ethanol manufacture that have high moisture contents and require significant energy for drying and conversion into dry distiller’s grains. Hydrothermal carbonization was investigated as a wet process to provide alternative products, and chars were obtained in moderate yield that possessed high heats of combustion. The mechanism of char formation was also investigated employing constituent materials representative of the chemical composition of distiller’s grains. Char formation was discovered to chiefly involve carbohydrates (other than cellulose) and proteins. A surprising discovery was that triacylglycerides and fatty acids created under the reaction conditions did not contribute to char yield and were adsorbed onto the chars and could be easily extracted.     

Co-rumination predicts the onset of depressive disorders during adolescence.

The tendency to co-ruminate, or frequently discuss and rehash problems with peers, may serve as one mechanism in the dramatic rise in depression observed during adolescence, particularly among adolescent girls. In the current study, our goal was (a) to test the hypothesis that adolescents' levels of co-rumination would predict the onset of clinically significant depressive episodes over a 2-year follow-up and (b) to determine whether levels of co-rumination would mediate gender differences in risk for depression onset. Both hypotheses were supported. Results of survival analysis revealed that adolescents with higher levels of co-rumination at the initial assessments exhibited a significantly shorter time to depression onset. Levels of co-rumination also mediated the gender difference in time to depression onset. These results were maintained even when adolescents' baseline levels of depressive symptoms and rumination were covaried statistically. Finally, co-rumination also predicted the course of illness in terms of episode severity and duration. Results suggest that co-rumination contributes a unique risk for the development of depression in adolescents. (PsycINFO Database Record (c) 2011 APA, all rights reserved)