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

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

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

Environmental and genetic influences on early attachment

Attachment theory predicts and subsequent empirical research has amply demonstrated that individual variations in patterns of early attachment behaviour are primarily influenced by differences in sensitive responsiveness of caregivers. However, meta-analyses have shown that parenting behaviour accounts for about one third of the variance in attachment security or disorganisation. The exclusively environmental explanation has been challenged by results demonstrating some, albeit inconclusive, evidence of the effect of infant temperament. In this paper, after reviewing briefly the well-demonstrated familial and wider environmental influences, the evidence is reviewed for genetic and gene-environment interaction effects on developing early attachment relationships. Studies investigating the interaction of genes of monoamine neurotransmission with parenting environment in the course of early relationship development suggest that children's differential susceptibility to the rearing environment depends partly on genetic differences. In addition to the overview of environmental and genetic contributions to infant attachment, and especially to disorganised attachment relevant to mental health issues, the few existing studies of gene-attachment interaction effects on development of childhood behavioural problems are also reviewed. A short account of the most important methodological problems to be overcome in molecular genetic studies of psychological and psychiatric phenotypes is also given. Finally, animal research focusing on brain-structural aspects related to early care and the new, conceptually important direction of studying environmental programming of early development through epigenetic modification of gene functioning is examined in brief

Lichen response to ammonia deposition defines the footprint of a penguin rookery

Ammonia volatilized from penguin rookeries is a major nitrogen source in Antarctic coastal terrestrial ecosystems. However, the spatial extent of ammonia dispersion from rookeries and its impacts have not been quantified previously. We measured ammonia concentration in air and lichen ecophysiological response variables proximate to an Adèlie penguin rookery at Cape Hallett, northern Victoria Land. Ammonia emitted from the rookery was 15N-enriched (δ15N value +6.9) and concentrations in air ranged from 36–75 µg m−3 at the rookery centre to 0.05 µg m−3 at a distance of 15.3 km. δ15N values and rates of phosphomonoesterase (PME) activity in the lichens Usnea sphacelata and Umbilicaria decussata were strongly negatively related to distance from the rookery and PME activity was positively related to thallus N:P mass ratio. In contrast, the lichen Xanthomendoza borealis, which is largely restricted to within an area 0.5 km from the rookery perimeter, had high N, P and 15N concentrations but low PME activity suggesting that nutrient scavenging capacity is suppressed in highly eutrophicated sites. An ammonia dispersion model indicates that ammonia concentrations sufficient to significantly elevate PME activity and δ15N values (≥0.1 µg NH3 m−3) occurred over c. 40–300 km2 surrounding the rookery suggesting that penguin rookeries potentially can generate large spatial impact zones. In a general linear model NH3 concentration and lichen species identity were found to account for 72 % of variation in the putative proportion of lichen thallus N originating from penguin derived NH3. The results provide evidence of large scale impact of N transfer from a marine to an N-limited terrestrial ecosystem

Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2&nbsp;m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0\u20135 and 5\u201315&nbsp;cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10\ub0C (mean&nbsp;=&nbsp;3.0&nbsp;\ub1&nbsp;2.1\ub0C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6&nbsp;\ub1&nbsp;2.3\ub0C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler ( 120.7&nbsp;\ub1&nbsp;2.3\ub0C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications