Forcing of the primary and secondary crossflow instability

With fossil fuels diminishing and fuel prices rising the development of more efficient aeroplanes is needed from an economical and environmental point of view. One possibility to increase the aerodynamic efficiency is to reduce the skin friction. This reduction can be achieved by having large areas of laminar flow. To be able to design laminar flow wings a thorough understanding of the transition from laminar to turbulent flow on a swept wing is needed. The current experimental investigation focuses on the influence of environmental disturbances on the development of the crossflow instability. In order to study this influence, in the low turbulence wind tunnel at City University of London, an experimental model had to be designed. It was chosen to have a 45 degrees swept flat plate with a displacement body placed above it which created a favourable pressure gradient on the plate. With the sweep angle and favourable pressure gradient the conditions to have a transition process dominated by the crossflow instability were met. To characterize the flow detailed single hot-wire scans were carried out with a custom made data acquisition system in LabVIEW. Prior to the experiments on the crossflow instability, measurements to characterize the freestream environment and to obtain the pressure distribution on the flat plate were carried out. The turbulence intensity was found to be around 0.02% for freestream velocities from 10 to 18m/s. The pressure distribution was obtained with two methods, with static pressure ports embedded in the plate and with a custom made pressure belt which spanwise location could easily be varied. Both methods gave comparable results and showed that a moderate favourable pressure gradient was created on the plate compared to other studies. The pressure belt results and panel code results were compared to a three-dimensional RANS computation of the set-up. A similar pressure gradient was found for all three pressure distributions. The magnitude of the pressure coefficient obtained from the panel code was slightly higher due to the inviscid character of this code. The main experiments focused on two stages of the transition process, the development of the primary and secondary crossflow instability. The goal of the primary crossflow instability experiments was to investigate the influence of the wavelength content of different roughness distributions while previous studies focused more on the roughness height. A cylindrical and pyramidal roughness elements were studied for this purpose. The roughness elements were spaced at a spanwise distance of λ, which was the wavelength of the most amplified stationary crossflow wave following linear stability analysis. From the calculation of the Fourier coefficients it followed that the pyramidal roughness distribution had stronger forcing at λ and weaker forcing at λ/n compared to the cylindrical roughness distribution. The experiments on the secondary instability first investigated the characteristics of this instability during different stages of its development. While in previous studies the characteristics in the early growth stage were studied here the characteristics of the secondary instability during breakdown are reported. Next, the experiments focused on excitation of the secondary instability by wall-forcing and freestream forcing. The secondary instability was forced from the wall with a small speaker. The results with different amplitudes of the excitation signal showed that the secondary instability is receptive for wall-forcing. The secondary instability was forced from the freestream through a small pipe which was connected to a speaker placed in the displacement body. The first experiments showed that the freestream forcing did not interact with the secondary instability in the boundary layer. Analogously to the travelling primary instability a thin roughness strip was placed on the swept flat plate at the location where the secondary instability started to grow. With the roughness in place an interaction between the freestream disturbances and secondary instability did occur and the phase structure of the secondary instability could be obtained

Study protocol: Cost-effectiveness of transmural nutritional support in malnourished elderly patients in comparison with usual care

BACKGROUND: Malnutrition is a common consequence of disease in older patients. Both in hospital setting and in community setting oral nutritional support has proven to be effective. However, cost-effectiveness studies are scarce. Therefore, the aim of our study is to investigate the effectiveness and cost-effectiveness of transmural nutritional support in malnourished elderly patients, starting at hospital admission until three months after discharge. METHODS: This study is a randomized controlled trial. Patients are included at hospital admission and followed until three months after discharge. Patients are eligible to be included when they are > or = 60 years old and malnourished according to the following objective standards: Body Mass Index (BMI in kg/m2) < 20 and/or > or = 5% unintentional weight loss in the previous month and/or > or = 10% unintentional weight loss in the previous six months. We will compare usual nutritional care with transmural nutritional support (energy and protein enriched diet, two additional servings of an oral nutritional supplement, vitamin D and calcium supplementation, and consultations by a dietitian). Each study arm will consist of 100 patients. The primary outcome parameters will be changes in activities of daily living (determined as functional limitations and physical activity) between intervention and control group. Secondary outcomes will be changes in body weight, body composition, quality of life, and muscle strength. An economic evaluation from a societal perspective will be conducted alongside the randomised trial to evaluate the cost-effectiveness of the intervention in comparison with usual care. CONCLUSION: In this randomized controlled trial we will evaluate the effect of transmural nutritional support in malnourished elderly patients after hospital discharge, compared to usual care. Primary endpoints of the study are changes in activities of daily living, body weight, body composition, quality of life, and muscle strength. An economic evaluation will be performed to evaluate the cost-effectiveness of the intervention in comparison with usual care. TRIAL REGISTRATION: Netherlands Trial Register (ISRCTN29617677, registered 14-Sep-2005)

Microfluidic systems for the analysis of the viscoelastic fluid flow phenomena in porous media

In this study, two microfluidic devices are proposed as simplified 1-D microfluidic analogues of a porous medium. The objectives are twofold: firstly to assess the usefulness of the microchannels to mimic the porous medium in a controlled and simplified manner, and secondly to obtain a better insight about the flow characteristics of viscoelastic fluids flowing through a packed bed. For these purposes, flow visualizations and pressure drop measurements are conducted with Newtonian and viscoelastic fluids. The 1-D microfluidic analogues of porous medium consisted of microchannels with a sequence of contractions/ expansions disposed in symmetric and asymmetric arrangements. The real porous medium is in reality, a complex combination of the two arrangements of particles simulated with the microchannels, which can be considered as limiting ideal configurations. The results show that both configurations are able to mimic well the pressure drop variation with flow rate for Newtonian fluids. However, due to the intrinsic differences in the deformation rate profiles associated with each microgeometry, the symmetric configuration is more suitable for studying the flow of viscoelastic fluids at low De values, while the asymmetric configuration provides better results at high De values. In this way, both microgeometries seem to be complementary and could be interesting tools to obtain a better insight about the flow of viscoelastic fluids through a porous medium. Such model systems could be very interesting to use in polymer-flood processes for enhanced oil recovery, for instance, as a tool for selecting the most suitable viscoelastic fluid to be used in a specific formation. The selection of the fluid properties of a detergent for cleaning oil contaminated soil, sand, and in general, any porous material, is another possible application

Low Mid-Upper Arm Circumference, Calf Circumference, and Body Mass Index and Mortality in Older Persons

Background.Low body mass index is a general measure of thinness. However, its measurement can be cumbersome in older persons and other simple anthropometric measures may be more strongly associated with mortality. Therefore, associations of low mid-upper arm circumference, calf circumference, and body mass index with mortality were examined in older persons.Methods.Data of the Longitudinal Aging Study Amsterdam, a population-based cohort study in the Netherlands, were used. The present study included community-dwelling persons 65 years and older in 1992-1993 (n = 1,667), who were followed until 2007 for their vital status. Associations between anthropometric measures and 15-year mortality were examined by spline regression models and, below the nadir, Cox regression models, transforming all measures to sex-specific Z scores.Results.Mortality rates were 599 of 826 (73%) in men and 479 of 841 (57%) in women. Below the nadir, the hazard ratio of mortality per 1 standard deviation lower mid-upper arm circumference was 1.79 (95% confidence interval, 1.48-2.16) in men and 2.26 (1.71-3.00) in women. For calf circumference, the hazard ratio was 1.45 (1.22-1.71) in men and 1.30 (1.15-1.48) in women and for body mass index 1.38 (1.17-1.61) in men and 1.56 (1.10-2.21) in women. Excluding deaths within the first 3 years after baseline did not change these associations. Excluding those with a smoking history, obstructive lung disease, or cancer attenuated the associations of calf circumference (men) and body mass index (women).Conclusions.Based on the stronger association with mortality and given a more easy assessment in older persons, mid-upper arm circumference seems a more feasible and valid anthropometric measure of thinness than body mass index in older men and women. © 2010 The Author. Published by Oxford University Press on behalf of The Gerontological Society of America

Pretreatment organ function in patients with advanced head and neck cancer: clinical outcome measures and patients' views

<p>Abstract</p> <p>Background</p> <p>Aim of this study is to thoroughly assess pretreatment organ function in advanced head and neck cancer through various clinical outcome measures and patients' views.</p> <p>Methods</p> <p>A comprehensive, multidimensional assessment was used, that included quality of life, swallowing, mouth opening, and weight changes. Fifty-five patients with stage III-IV disease were entered in this study prior to organ preserving (chemoradiation) treatment.</p> <p>Results</p> <p>All patients showed pretreatment abnormalities or problems, identified by one or more of the outcome measures. Most frequent problems concerned swallowing, pain, and weight loss. Interestingly, clinical outcome measures and patients' perception did no always concur. E.g. videofluoroscopy identified aspiration and laryngeal penetration in 18% of the patients, whereas only 7 patients (13%) perceived this as problematic; only 2 out of 7 patients with objective trismus actually perceived trismus.</p> <p>Conclusion</p> <p>The assessment identified several problems already pre-treatment, in this patient population. A thorough assessment of both clinical measures and patients' views appears to be necessary to gain insight in all (perceived) pre-existing functional and quality of life problems.</p

Exploring immune status in peripheral blood and tumor tissue in association with survival in patients with multi-organ metastatic colorectal cancer

Colorectal cancer (CRC) raises considerable clinical challenges, including a high mortality rate once the tumor spreads to distant sites. At this advanced stage, more accurate prediction of prognosis and treatment outcome is urgently needed. The role of cancer immunity in metastatic CRC (mCRC) is poorly understood. Here, we explore cellular immune cell status in patients with multi-organ mCRC. We analyzed T cell infiltration in primary tumor sections, surveyed the lymphocytic landscape of liver metastases, and assessed circulating mononuclear immune cells. Besides asking whether immune cells are associated with survival at this stage of the disease, we investigated correlations between the different tissue types; as this could indicate a dominant immune phenotype. Taken together, our analyses corroborate previous observations that higher levels of CD8+ T lymphocytes link to better survival outcomes. Our findings therefore extend evidence from earlier stages of CRC to indicate an important role for cancer immunity in disease control even after metastatic spreading to multiple organs. This finding may help to improve predicting outcome of patients with mCRC and suggests a future role for immunotherapeutic strategies.</p

On the effect of discrete roughness on the growth of crossflow instability in very low turbulence environment

Wind tunnel experiments were conducted in a low-turbulence environment (Tu < 0.006%) on the stability of 3D boundary layers. The effect of two different distributions of discrete roughness elements (DREs) on crossflow vortices disturbances and their growth was evaluated. As previously reported, DREs are found to be an effective tool in modulating the behaviour of crossflow modes. However, the effect of 24µm DREs was found to be weaker than previously thought, possibly due to the low level of environmental disturbances herewith. Preliminary results suggest that together with the height of the DREs and their spanwise spacing, their physical distribution across the surface also intimately affects the stability of 3D boundary layers. Finally, crossflow vortices are tracked along the chord of the model and their merging is captured. This phenomena is accompanied by a change in the critical wavelength of the dominant mode

Beneficial immune modulatory effects of a specific nutritional combination in a murine model for cancer cachexia

The majority of patients with advanced cancer are recognised by impaired immune competence influenced by several factors, including the type and stage of the tumour and the presence of cachexia. Recently, a specific nutritional combination containing fish oil, specific oligosaccharide mixture, high protein content and leucine has been developed aimed to support the immune system of cancer patients in order to reduce the frequency and severity of (infectious) complications. In a recently modified animal model cachexia is induced by inoculation of C26 tumour cells in mice. In a pre-cachectic state, no effect was observed on contact hypersensitivity, a validated in vivo method to measure Th1-mediated immune function, after adding the individual nutritional ingredients to the diet of tumour-bearing mice. However, the complete mixture resulted in significantly improved Th1 immunity. Moreover, in a cachectic state, the complete mixture reduced plasma levels of pro-inflammatory cytokines and beneficially affected ex vivo immune function. Accordingly, the combination of the nutritional ingredients is required to obtain a synergistic effect, leading to a reduced inflammatory state and improved immune competence. From this, it can be concluded that the specific nutritional combination has potential as immune-supporting nutritional intervention to reduce the risk of (infectious) complications in cancer patients

A prospective investigation of swallowing, nutrition, and patient-rated functional impact following altered fractionation radiotherapy with concomitant boost for oropharyngeal cancer

Altered fractionation radiotherapy for head and neck cancer has been associated with improved locoregional control, overall survival, and heightened toxicity compared with conventional treatment. Swallowing, nutrition, and patient-perceived function for altered fractionation radiotherapy with concomitant boost (AFRT-CB) for T1–T3 oropharyngeal squamous cell carcinoma (SCC) have not been previously reported. Fourteen consecutive patients treated with AFRT-CB for oropharyngeal SCC were recruited from November 2006 to August 2009 in a tertiary hospital in Brisbane, Australia. Swallowing, nutrition, and patient-perceived functional impact assessments were conducted pretreatment, at 4–6 weeks post-treatment, and at 6 months post-treatment. Deterioration from pretreatment to 4–6 weeks post-treatment in swallowing, nutrition, and functional impact was evident, likely due to the heightened toxicity associated with AFRT-CB. There was significant improvement at 6 months post-treatment in functional swallowing, nutritional status, patient-perceived swallowing, and overall function, consistent with recovery from acute toxicity. However, weight and patient perception of physical function and side effects remained significantly worse than pretreatment scores. The ongoing deficits related to weight and patient-perceived outcomes at 6 months revealed that this treatment has a long-term impact on function possibly related to the chronic effects of AFRT-CB