BACKGROUND In a previous study we showed that prolonged nasogastric tube feeding is associated with pathogenic oral flora. OBJECTIVE To reexamine the impact of prolonged nasogastric tube feeding on the oral microbiota and to explore the salivary flow and composition in elderly patients in long-term care. METHODS We compared a group of elderly patients fed by nasogastric tube with a control ...

One-dimensional stability analysis of a hydraulic system composed of a penstock, a runner, and a draft tube was carried out to determine the cause of the full load draft tube surge. It is assumed that the cavity volume at the runner exit is a function of the pressure at the vortex core evaluated from the instantaneous local pressure at the runner exit and an additional pressure decrease due to ...

Over 85% of all new heat exchanger applications in oil refining, chemical, petro-chemical, and power generation are accommodated through the use of conventional shell and tube type heat exchangers. The fundamental basis for this statistic is shell and tube technology is a cost effective, proven solution for a wide variety of heat transfer requirements. However, there are limitations associated ...

The time evolution of the flow parameters in a system where gas is expanded from a high pressure chamber through a tube toward a low pressure chamber is investigated. During the process, the pressure in the two chambers is changing in the opposite direction, while the flow rate is reduced until the system reaches its equilibrium state. Rarefied conditions may be present. Based on the observatio...

The steady state solutions of two mathematical models are used to evaluate Münch's pressure-flow hypothesis of phloem translocation. The models assume a continuous active loading and unloading of translocate but differ in the site of loading and unloading and the route of water to the sieve tube. The dimensions of the translocation system taken are the average observed values for sugar beet and...

This paper presents the application of finite element method (FEM) to analyze the tube temperature distribution in a water tube boiler. Two-dimensional (2-D) finite element models are developed where the axi-symmetric triangular elements for the cross section area along the water tube are applied in computer software namely MSC Patran-Nastran. The analysis of the temperature distribution for ev...

In this paper we examine the effect of mild stenosis on blood flow, in an irregular axisymmetric artery with oscillating pressure gradient. The Herschel-Bulkley fluid model has been utilized for this study. The combined influence of an asymmetric shape and surface irregularities of constriction has been explored in this computational study. An extensive quantitative analysis has been performed ...

We construct a valveless pump consisting of a section of elastic tube and a section of rigid tube, connected in a closed loop and filled with water. By periodically squeezing the elastic tube at an asymmetric location, a persistent flow around the tubes is created. This effect, called the Liebau phenomenon or valveless pumping, has been known for some time, but is still poorly understood. We st...

Since the first ultrastructural investigations of sieve tubes in the early 1960s, their structure has been a matter of debate. Because sieve tube structure defines frictional interactions in the tube system, the presence of P protein obstructions shown in many transmission electron micrographs led to a discussion about the mode of phloem transport. At present, it is generally agreed that P prot...

We report results of unsteady, harmonic flow simulations with the lattice BGK method in two-dimensional elastic tubes. The tubes are assumed to obey a simple constitutive equation, linearly relating the diameter of the tube to the pressure difference inside and outside the tube. First, as a benchmark, we present results of steady flow in such elastic tubes, and compare the performance of three ...