Daytime Sessions Research Articles

Effect of a Nonrebreathing Exhalation Valve on Long-term Nasal Ventilation Using a Bilevel Device

To determine whether an exhalation valve designed to minimize rebreathing improves daytime or nocturnal gas exchange or improves symptoms compared with a traditional valve during nocturnal nasal ventilation delivered using a bilevel pressure ventilation device. Prospective direct comparison trial with each patient sequentially using both valves, during a 2-week run-in period with a traditional valve, a 2-week trial with the nonrebreathing valve, and a 2-week washout period with the traditional valve. Outpatient pulmonary function laboratory and home nocturnal monitoring. Seven patients who received long-term (> 1 year) nocturnal nasal bilevel pressure ventilation with an expiratory pressure of <or= 4 cm H(2)O. Symptoms, pulmonary function, and arterial blood gas levels were assessed at each of three daytime sessions after the sequential 2-week periods using the different valves. Nocturnal studies used a multichannel recorder that measured heart rate, chest wall impedance, nasal airflow, and oximetry. End-tidal PCO(2) (PetCO(2)) from the mask and transcutaneous PCO(2) (PtcCO(2)) were also monitored nocturnally. Seven patients with a variety of neuromuscular, chest wall, and obstructive defects were enrolled. No mean differences in daytime arterial blood gas levels, pulmonary functions, nocturnal vital signs or oximetry, or PtcCO(2) were apparent regardless of the exhalation valve used. The multichannel recording was indicative of an air leak at least one third of the time, and the PetCO(2) tracing detected a blunted signal or no signal from the mask during the majority of the recording time. The use of an exhalation valve designed to minimize rebreathing did not improve daytime or nocturnal gas exchange or symptoms in patients receiving long-term nasal bilevel pressure ventilation in comparison with a traditional exhalation valve, most likely because of air leakage and escape of CO(2) via other routes.

Is after-hours trading informative?

This article investigates price and trading volume relations for near term crude oil contracts at the New York Mercantile Exchange (NYMEX). The study investigates the informativeness of after-hours trading under the prior assumption that daytime and after-hours trading sessions are completely segmented. The research methodology uses a vector autoregressive (VAR) structural model to identify the lead/lag structure between the leading overnight session and the lagging daytime session. This framework permits us to impose testable restrictions in considering the view that after-hours price changes and trading volumes provide contemporaneous information in the daytime price discovery process. Furthermore, the reduced-form VAR allows testing whether innovations (surprises) in daytime prices and trading activity influence overnight price/volume behavior.

Study of small variations of troposphere parameters by the radioacoustic sounding method

We consider a method based on the study of signal amplitude and phase variations in the radioacoustic sounding (RAS) of the atmosphere for the diagnostics of dynamical and wave processes in the troposphere. We give experimental data on phase variations of the RAS signal from scan to scan in daytime and nighttime sessions. Variations of the signal phase with characteristic time greater than 40 min are likely due to the passage of internal gravity waves (IGW) through the sounding region. The experimental data are in good agreement with the results of computer simulation of IGW propagation.

Psychic Reactions to Long‐Term Hemodialysis: Evaluation in the Elderly by Means of the Draw‐A‐Person Test†

Twelve patients who attended a daytime session in a hemodialysis unit were studied. Most were older than patients whose adaptation has been the subject of previous reports. Problems of life satisfaction for these elderly patients often are different from those for younger persons. Most of the group showed maladaptive reactions which interfered with their activities when away from the unit. The Draw-A-Person test was a useful tool in pinpointing these reactions, which can lead to feelings of helplessness and depression. Factors which encourage good adaptation to long-term hemodialysis are discussed.