Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

A computational study on the momentum and heat transfer distribution of a low frequency round impinging synthetic jet

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Impinging synthetic jets have been considered as a possible solution for cooling miniature structures. It has been shown that synthetic jet performance is sensitive to the distance between the jet nozzle and the target surface where enhancement of heat transfer decreases with a reduction in nozzle-to-target plate distance. At low nozzle-to-target spacing, no detailed information about the momentum and temperature fields have been shown in prior literature, therefore further investigation is needed. In this study, a 3-D computational fluid dynamics model was constructed to determine the flow and temperature fields of a meso-scale synthetic jet at a nozzle-to-target surface spacing of H/D = 2, ReD,j= 1400 and f = 500 Hz. Unlike the majority of previous computational studies, rather than specifying the boundary conditions at the nozzle, the flow inside the synthetic jet device was solved by specifying the time dependent boundary conditions on the vibrating diaphragm and utilizing the moving mesh technique. Local surface pressure and heat transfer coefficient distributions were determined and discussed. It was found that the pulsating flow at the nozzle exit for a round jet generates vortex rings and these rings seem to have some considerable effects on the target surface profiles

An experimental and computational investigation of a thin piezofan cooler

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Recent trends in electronic cooling systems are targeted towards a reduction in size, therefore small form factor/miniature cooling devices are of interest to various applications. Among these devices are piezoelectric fans which are simply made of vibrating plates and shed vortices from their leading edge and enhance heat transfer from nearby target surfaces. This paper investigates the flow and temperature fields produced by a piezoelectric fan. An experimental study is performed to determine the temperature distribution of a vertically heated surface under various fan tip-to-target surface distances and driving conditions of the piezoelectric device (frequency). 2-D numerical simulations are carried out to predict the momentum and temperature fields in the domain of interest under the same boundary conditions of the experimental effort. The numerical results are in reasonably good agreement with the measured experimental data. The relevant dimensionless parameters such as Nusselt, Strouhal, and Keulegan-Carpenter numbers are determined. With a maximum Nusselt number of 20 and 57 for mylar and metallic piezo fans, respectively, the corresponding Strouhal, and Keulegan-Carpenter numbers suggest that a vortex formation occurs at the blade tip, however these vortices are weak such that they are neither able to approach the target surface as high strength structures nor improve heat removal significantly for the range of measurements.Aselsan ; SSM (undersecretary of Turkish ministry of defense) ; Istanbul Development Agenc

A computational study on the momentum and heat transfer distribution of a low frequency round impinging synthetic jet

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Impinging synthetic jets have been considered as a possible solution for cooling miniature structures. It has been shown that synthetic jet performance is sensitive to the distance between the jet nozzle and the target surface where enhancement of heat transfer decreases with a reduction in nozzle-to-target plate distance. At low nozzle-to-target spacing, no detailed information about the momentum and temperature fields have been shown in prior literature, therefore further investigation is needed. In this study, a 3-D computational fluid dynamics model was constructed to determine the flow and temperature fields of a meso-scale synthetic jet at a nozzle-to-target surface spacing of H/D = 2, ReD,j= 1400 and f = 500 Hz. Unlike the majority of previous computational studies, rather than specifying the boundary conditions at the nozzle, the flow inside the synthetic jet device was solved by specifying the time dependent boundary conditions on the vibrating diaphragm and utilizing the moving mesh technique. Local surface pressure and heat transfer coefficient distributions were determined and discussed. It was found that the pulsating flow at the nozzle exit for a round jet generates vortex rings and these rings seem to have some considerable effects on the target surface profiles

Acoustic analysis of an axial fan

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Axial fans are often used in cooling electronic enclosures where low noise levels are highly demanded. Therefore, methods for predicting the noise emitted by an application including single or multiple fans are desirable to improve, stimulate and reduce the cost of low-noise design. The prediction of sound generated from fluid flow has been difficult due to the non-linear form of the governing equations, however, recent developments in computational fluid dynamics (CFD) and computational acoustics allow us to determine sound pressure levels (SPL) in a fluid flow. In this study, time dependent flow field produced by an axial fan is computed via Large Eddy Simulations (LES), and the consequent sound pressure map is determined using the Ffowcs Williams-Hawkings (FW-H) model. Since an axial fan is a complex source of sound, for engineering design purposes, simplifications are needed when modelling its acoustic characteristics, therefore, the sound radiation of an axial fan in free space is examined by expanding the generated sound pressure field into spherical harmonics. In addition, acoustic measurements are carried out in a semi-anechoic chamber to validate the aforementioned computational models and make necessary comparisons. Comparison of the numerical results against the experimental data shows that, despite some discrepancies, the former is able to capture the trends observed in the measurements.Aselsan ; SSM (undersecretary of Turkish ministry of defense) ; Istanbul Development Agenc

Investigation of power distribution on an axial fan

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Forced convection cooling systems utilize fans which can be axial or radial, small or large in many different configurations. Efficiency of a fan depends on its electrical and mechanical designs as well as the environmental conditions that the fan is exposed to. Typically, the overall efficiency of an axial fan varies between 15 to 40 percent. Power losses may be due to electrical, aerodynamic or mechanical design components. Losses occurring in an axial fan motor have become a critical issue in which high inertial effects, low power, low cost and high efficiency are desired. In order to design an efficient motor, it is important to accurately predict the power losses which are normally dissipated in the form of heat. The present study starts with an investigation of the power losses of an axial fan experimentally and computationally. Moreover, it deals with modeling of mechanical, electrical, thermal and electromagnetic losses which focus especially on an outer rotor brushless DC motor. Reduction of these losses leads to a decrease in the motor temperature and, therefore, has a positive effect on the fan reliability. Expressions for calculating the inverter losses, motor losses and mechanical losses are derived. The power losses obtained are then used as heat sources when evaluating the thermal performance of the motor. By using a two-dimensional model, computational fluid dynamics (CFD) simulations are performed to determine the iron losses across the motor. These results are utilized to determine evaluate the overall efficiency of the system.Aselsan ; SSM (undersecretary of Turkish ministry of defense

Investigation of power distribution on an axial fan

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Forced convection cooling systems utilize fans which can be axial or radial, small or large in many different configurations. Efficiency of a fan depends on its electrical and mechanical designs as well as the environmental conditions that the fan is exposed to. Typically, the overall efficiency of an axial fan varies between 15 to 40 percent. Power losses may be due to electrical, aerodynamic or mechanical design components. Losses occurring in an axial fan motor have become a critical issue in which high inertial effects, low power, low cost and high efficiency are desired. In order to design an efficient motor, it is important to accurately predict the power losses which are normally dissipated in the form of heat. The present study starts with an investigation of the power losses of an axial fan experimentally and computationally. Moreover, it deals with modeling of mechanical, electrical, thermal and electromagnetic losses which focus especially on an outer rotor brushless DC motor. Reduction of these losses leads to a decrease in the motor temperature and, therefore, has a positive effect on the fan reliability. Expressions for calculating the inverter losses, motor losses and mechanical losses are derived. The power losses obtained are then used as heat sources when evaluating the thermal performance of the motor. By using a two-dimensional model, computational fluid dynamics (CFD) simulations are performed to determine the iron losses across the motor. These results are utilized to determine evaluate the overall efficiency of the system.Aselsan ; SSM (undersecretary of Turkish ministry of defense