Hoffman et al. proposed a convenient collapsibility test in Cox regression [1]. Collapsibility tests have been considered as an effective way to select confounders to be included in multiplicative rate models [2]. However, it is not reasonable to expect that the performance of a confounder-selection procedure (CSP) using the Hoffman’s test is as shown in [2]. First, unlike multiplicative rate m...

BACKGROUND Central venous pressure (CVP) and right atrial pressure (RAP) are important parameters in the complete hemodynamic assessment of a patient. Sonographic measurement of the inferior vena cava (IVC) diameter is a non-invasive method of estimating these parameters, but there are limited data summarizing its diagnostic accuracy across multiple studies. We performed a comprehensive review ...

The effects of [+/-]-2,5-dimethoxy-4-iodoaminophentamine, a serotonin(2A/2C) receptor agonist, on pharyngeal airflow mechanics were examined in isoflurane-anesthetized lean and obese Zucker rats. The pharyngeal pressure associated with flow limitation, maximum inspiratory flow, oronasal resistance, genioglossus muscle activity, and arterial blood pressure (BP) were measured before and after the...

OBJECTIVE To evaluate the effect of selective electrical stimulation of the tensor veli palatini muscle on upper airway patency. METHODS Pressure-flow relationships were evaluated, in a feline isolated upper airway preparation, to determine the role of the soft palate musculature on airflow dynamics. The tensor veli palatini muscles were selectively stimulated while monitoring upper airway co...

Increased upper airways (UA) collapsibility has been implicated in the pathogeny of sleep-disordered breathing (SDB). An increased UA instability during expiration has recently been shown in healthy subjects. The present study assessed UA collapsibility in SDB patients by applying negative pressure during expiration. Full-night polysomnography was performed in 16 subjects (all snorers) with a w...

Sleep-disordered breathing has been shown to be more prevalent in patients with spinal cord injury (SCI) than the general population. The pathogenesis of increased sleep-disordered breathing in individuals with chronic SCI is unknown. The purpose of this study is to determine whether SCI level affects upper airway (UA) collapsibility and neuromuscular compensatory responses to obstruction. Twen...

Origami has been employed to build deployable mechanical metamaterials through folding and unfolding along the crease lines. Deployable metamaterials are usually flexible, particularly along their deploying and collapsing directions, which unfortunately in many cases leads to an unstable deployed state, i.e., small perturbations may collapse the structure along the same deployment path. Here we...

We introduce the theory of strong homotopy types of simplicial complexes. Similarly to classical simple homotopy theory, the strong homotopy types can be described by elementary moves. An elementary move in this setting is called a strong collapse and it is a particular kind of simplicial collapse. The advantage of using strong collapses is the existence and uniqueness of cores and their relati...

Lung volume dependence of pharyngeal airway patency suggests involvement of lung volume in pathogenesis of obstructive sleep apnea. We examined the structural interaction between passive pharyngeal airway and lung volume independent of neuromuscular factors. Static mechanical properties of the passive pharynx were compared before and during lung inflation in eight anesthetized and paralyzed pat...

Collapsible pharyngeal airway size is determined by interaction between structural properties of the pharyngeal airway and neural regulation of the pharyngeal dilating muscles. Obesity seems to have two distinct mechanical influences on the pharyngeal airway collapsibility. First, obesity increases soft tissue surrounding the pharyngeal airway within limited maxillomandible enclosure occupying ...