Detection of confounding and confounders is important for observational studies, and especially so for epidemiologic studies. Miettinen and Cook (1981) derived two criteria for detecting confounders. Using a model, Wickramaratne and Holford (1987) proved that the two criteria are necessary but not sufficient conditions for confounders. We take uniform nonconfounding to mean there is no confound...

In this research, the results of comparative analysis of a single fuel droplet evaporation models are presented. Three well-known evaporation models including Spalding, Borman-Johnson and Abramzon-Sirignano models are analyzed using Computational Fluid Dynamic (CFD). The original Spalding model is extended to consider the effects of the Stefan flow, unsteady vaporization, and variable propertie...

The first-hitting-time based model conceptualizes a random process for subjects’ latent health status. time-to-event outcome is modeled as the first hitting time of to pre-specified threshold. Threshold regression with linear predictors has numerous benefits in causal survival analysis, such estimators’ collapsibility. We propose neural network extension threshold model. With flexibility networ...

BACKGROUND This study investigated the effect of varying concentrations of propofol on upper airway collapsibility and the mechanisms responsible for it. METHODS Upper airway collapsibility was determined from pressure-flow relations at three concentrations of propofol anesthesia (effect site concentration = 2.5, 4.0, and 6.0 mug/ml) in 12 subjects spontaneously breathing on continuous positi...

To examine the dynamic modulation of upper airway (UA) function during sleep, we devised a novel approach to measuring the critical pressure (Pcrit) within a single breath in tracheostomized sleep apnea patients. We hypothesized that the UA continuously modulates airflow dynamics during transtracheal insufflation. In this study, we examine tidal pressure-flow relationships throughout the respir...

Idiopathic intracranial hypertension (IIH) is a syndrome of unknown cause characterized by elevated intracranial pressure (ICP). While imaging often reveals a stenosis of the transverse sinuses, the role of this feature in IIH has been in dispute. Many patients with chronic daily headache have been found to actually be suffering from a milder form of IIH without papilledema (IIHWOP). These pati...

Objective: Ultrasound assessment of inferior vena cava (IVC) collapsibility is performed to determine the volume status critically ill patients. We propose a new acoustic window for visualizing vein in prone patient. Case Presentation: A healthy volunteer took part study. The study protocol includes two stages: 1) performing magnetic resonance imaging (MRI) examination projection certain IVC ar...

Loess is a kind of special sediment with pore structure and rich carbonate in its composition. Due to the characteristics composition, most loess has collapsibility. There are resources distributed northwest area China. With improvement traffic network west area, use as roadbed gradually increasing. Therefore, during construction process, engineering problems encountered by also increased, whic...