scholarly journals Coupling of Ultrasonic and Photometric Techniques for Synchronous Measurements of Unconfined Turbidity Currents

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1246
Author(s):  
Richard Wilson ◽  
Heide Friedrich
Keyword(s):  
Rough Surface ◽  
Smooth Surface ◽  
Environmental Flows ◽  
Measurement Techniques ◽  
Flow Characteristics ◽  
Future Research ◽  
Turbidity Currents ◽  
Valuable Insight ◽  
Local Intensity ◽  
Cleft Formation

By synchronizing data collection, such as photometric and ultrasonic Doppler profiling (UVP) measurement techniques, new insights can be obtained into environmental flows, such as highly dynamic turbidity currents. We introduce a combined experimental setup, which ultimately allows a time reduction in testing programmes, and discuss the measurement advances with the help of four surface conditions we tested for unconfined turbidity currents: (a) a smooth surface; (b) a smooth surface with an obstacle present; (c) a rough surface; and (d) a rough surface with an obstacle present. We show that data from both measurement techniques indicate that a rough surface reduces global current velocities and the magnitude of turbidity current phenomena, including Kelvin-Helmholtz instabilities and lobe-and-cleft formation. However, by coupling the techniques, photometric data give valuable insight into the spatial development of instabilities, such as the grouping of lobe and cleft formations. The presence of an obstacle causes local regions of an increased and decreased velocity, but does not affect the global current velocity. Additionally, the obstacle created three local intensity maxima upstream, dissipating to two maxima downstream, supporting the presence of local eddies. The study shows that the combination of UVP and photometry is an effective way forward for obtaining detailed qualitative and quantitative insights into turbulent flow characteristics and we highlight the potential for future research.

scholarly journals Dietary nitrate and population health: a narrative review of the translational potential of existing laboratory studies

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Oliver M. Shannon ◽  
Chris Easton ◽  
Anthony I. Shepherd ◽  
Mario Siervo ◽  
Stephen J. Bailey ◽  
...  
Keyword(s):  
Population Health ◽  
Leafy Vegetables ◽  
Future Research ◽  
Research Approach ◽  
Valuable Insight ◽  
Main Body ◽  
Laboratory Studies ◽  
Potential Health ◽  
Health Promoting

Abstract Background Dietary inorganic nitrate (NO3−) is a polyatomic ion, which is present in large quantities in green leafy vegetables and beetroot, and has attracted considerable attention in recent years as a potential health-promoting dietary compound. Numerous small, well-controlled laboratory studies have reported beneficial health effects of inorganic NO3− consumption on blood pressure, endothelial function, cerebrovascular blood flow, cognitive function, and exercise performance. Translating the findings from small laboratory studies into ‘real-world’ applications requires careful consideration. Main body This article provides a brief overview of the existing empirical evidence basis for the purported health-promoting effects of dietary NO3− consumption. Key areas for future research are then proposed to evaluate whether promising findings observed in small animal and human laboratory studies can effectively translate into clinically relevant improvements in population health. These proposals include: 1) conducting large-scale, longer duration trials with hard clinical endpoints (e.g. cardiovascular disease incidence); 2) exploring the feasibility and acceptability of different strategies to facilitate a prolonged increase in dietary NO3− intake; 3) exploitation of existing cohort studies to explore associations between NO3− intake and health outcomes, a research approach allowing larger samples sizes and longer duration follow up than is feasible in randomised controlled trials; 4) identifying factors which might account for individual differences in the response to inorganic NO3− (e.g. sex, genetics, habitual diet) and could assist with targeted/personalised nutritional interventions; 5) exploring the influence of oral health and medication on the therapeutic potential of NO3− supplementation; and 6) examining potential risk of adverse events with long term high- NO3− diets. Conclusion The salutary effects of dietary NO3− are well established in small, well-controlled laboratory studies. Much less is known about the feasibility and efficacy of long-term dietary NO3− enrichment for promoting health, and the factors which might explain the variable responsiveness to dietary NO3− supplementation between individuals. Future research focussing on the translation of laboratory data will provide valuable insight into the potential applications of dietary NO3− supplementation to improve population health.

scholarly journals Participants' Perspectives on the Feasibility of a Novel, Intensive, Task-Specific Intervention for Individuals With Chronic Stroke: A Qualitative Analysis

2013 ◽  
Vol 93 (2) ◽  
pp. 147-157 ◽  
Author(s):  
Angela R. Merlo ◽  
Ashley Goodman ◽  
Bruce A. McClenaghan ◽  
Stacy L. Fritz
Keyword(s):  
Qualitative Analysis ◽  
Muscle Soreness ◽  
Therapeutic Option ◽  
Phenomenological Approach ◽  
Chronic Stroke ◽  
Qualitative Inquiry ◽  
Feasibility Trial ◽  
Future Research ◽  
Valuable Insight ◽  
Specific Intervention

BackgroundEvidence-based practice promotes patient-centered care, yet the majority of rehabilitative research fails to take patient perspectives into consideration. Qualitative research provides a unique opportunity for patients to express opinions and provide valuable insight on intervention processes.ObjectiveThe purpose of this study was to assess the feasibility of a novel, intensive, task-specific intervention from the patient's perspective.DesignA phenomenological approach to qualitative inquiry was used.MethodsEight individuals with chronic stroke participated in an intensive intervention, 3 hours per day for 10 consecutive days. Participants were interviewed twice regarding their impressions of the therapy, and a focus group was conducted with participants and family members. Data analysis included an analytical thematic approach.ResultsFive major themes arose related to the feasibility of the intervention: (1) a manageable amount of fatigue; (2) a difficult, yet doable, level of intensity; (3) a disappointingly short therapy duration; (4) enjoyment of the intervention; and (5) muscle soreness.ConclusionsThe findings suggest that participants perceived this novel and intensive, task-specific intervention as a feasible therapeutic option for individuals with chronic stroke. Despite the fatigue and muscle soreness associated with intensive rehabilitation, participants frequently reported enjoying the therapy and stated disappointment with the short duration (10 days). Future research should include a feasibility trial of longer duration, as well as a qualitative analysis of the benefits associated with the intervention.

scholarly journals Modeling of Breaching-Generated Turbidity Currents Using Large Eddy Simulation

2020 ◽  
Vol 8 (9) ◽  
pp. 728
Author(s):  
Said Alhaddad ◽  
Lynyrd de Wit ◽  
Robert Jan Labeur ◽  
Wim Uijttewaal
Keyword(s):  
Experimental Data ◽  
Numerical Model ◽  
Large Eddy Simulation ◽  
Flow Characteristics ◽  
Turbidity Current ◽  
Turbidity Currents ◽  
Eddy Simulation ◽  
Failure Evolution ◽  
Large Eddy ◽  
Flow Slides

Breaching flow slides result in a turbidity current running over and directly interacting with the eroding, submarine slope surface, thereby promoting further sediment erosion. The investigation and understanding of this current are crucial, as it is the main parameter influencing the failure evolution and fate of sediment during the breaching phenomenon. In contrast to previous numerical studies dealing with this specific type of turbidity currents, we present a 3D numerical model that simulates the flow structure and hydrodynamics of breaching-generated turbidity currents. The turbulent behavior in the model is captured by large eddy simulation (LES). We present a set of numerical simulations that reproduce particular, previously published experimental results. Through these simulations, we show the validity, applicability, and advantage of the proposed numerical model for the investigation of the flow characteristics. The principal characteristics of the turbidity current are reproduced well, apart from the layer thickness. We also propose a breaching erosion model and validate it using the same series of experimental data. Quite good agreement is observed between the experimental data and the computed erosion rates. The numerical results confirm that breaching-generated turbidity currents are self-accelerating and indicate that they evolve in a self-similar manner.

scholarly journals Sodankylä manual snow survey program

2016 ◽  
Vol 5 (1) ◽  
pp. 163-179 ◽  
Author(s):  
Leena Leppänen ◽  
Anna Kontu ◽  
Henna-Reetta Hannula ◽  
Heidi Sjöblom ◽  
Jouni Pulliainen
Keyword(s):  
Snow Water Equivalent ◽  
Measurement Techniques ◽  
Liquid Water Content ◽  
The Arctic ◽  
Research Centre ◽  
Future Research ◽  
Forest Zone ◽  
Finnish Meteorological Institute ◽  
Snow Properties ◽  
Snow Water

Abstract. The manual snow survey program of the Arctic Research Centre of the Finnish Meteorological Institute (FMI-ARC) consists of numerous observations of natural seasonal taiga snowpack in Sodankylä, northern Finland. The easily accessible measurement areas represent the typical forest and soil types in the boreal forest zone. Systematic snow measurements began in 1909 with snow depth (HS) and snow water equivalent (SWE). In 2006 the manual snow survey program expanded to cover snow macro- and microstructure from regular snow pits at several sites using both traditional and novel measurement techniques. Present-day snow pit measurements include observations of HS, SWE, temperature, density, stratigraphy, grain size, specific surface area (SSA) and liquid water content (LWC). Regular snow pit measurements are performed weekly during the snow season. Extensive time series of manual snow measurements are important for the monitoring of temporal and spatial changes in seasonal snowpack. This snow survey program is an excellent base for the future research of snow properties.

scholarly journals A review of biomass burning emissions, part II: Intensive physical properties of biomass burning particles

2004 ◽  
Vol 4 (5) ◽  
pp. 5135-5200 ◽  
Author(s):  
J. S. Reid ◽  
R. Koppmann ◽  
T. F. Eck ◽  
D. P. Eleuterio
Keyword(s):  
Particle Size ◽  
Biomass Burning ◽  
Measurement Techniques ◽  
Emission Factors ◽  
Future Research ◽  
Data Set ◽  
Particle Properties ◽  
In Situ Experiments ◽  
Literature Base ◽  
Biomass Burning Particles

Abstract. The last decade has seen tremendous advances in atmospheric aerosol particle research that is often performed in the context of climate and global change science. Biomass burning, one of the largest sources of accumulation mode particles globally, has been closely studied for its radiative, geochemical, and dynamic impacts. These studies have taken many forms including laboratory burns, in situ experiments, remote sensing, and modeling. While the differing perspectives of these studies have ultimately improved our qualitative understanding of biomass burning issues, the varied nature of the work make inter-comparisons and resolutions of some specific issues difficult. In short, the literature base has become a milieu of small pieces of the biomass-burning puzzle. This manuscript, the second part of four, examines the properties of biomass-burning particle emissions. Here we review and discuss the literature concerning the measurement of smoke particle size, chemistry, thermodynamic properties, and emission factors. Where appropriate, critiques of measurement techniques are presented. We show that very large differences in measured particle properties have appeared in the literature, in particular with regards to particle carbon budgets. We investigate emissions uncertainties using scale analyses, which shows that while emission factors for grass and brush are relatively well known, very large uncertainties still exist in emission factors of boreal, temperate and some tropical forests. Based on an uncertainty analysis of the community data set of biomass burning measurements, we present simplified models for particle size and emission factors. We close this review paper with a discussion of the community experimental data, point to lapses in the data set, and prioritize future research topics.

scholarly journals Homotopy pertubation method analysis to MHD flow of a radiative nanofluid with viscous dissipation and ohmic heating over a stretching porous plate

2018 ◽  
Vol 22 (1 Part B) ◽  
pp. 413-422 ◽  
Author(s):  
Hitesh Kumar
Keyword(s):  
Boundary Layer ◽  
Viscous Dissipation ◽  
Reverse Flow ◽  
Ohmic Heating ◽  
Complete Solution ◽  
Porous Plate ◽  
Flow Characteristics ◽  
Mhd Flow ◽  
Future Research ◽  
Layer Flow

An analytical study is performed to explore the flow and heat transfer characteristics of nanofluid (Al2O3-water and TiO3-water) over a linearly stretching porous sheet in the presence of radiation, ohmic heating, and viscous dissipation. Homotopy perturbed method is used and complete solution is presented, the results for the nanofluids velocity and temperature are obtained. The effects of various thermophysical parameters on the boundary-layer flow characteristics are displayed graphically and discussed quantitatively. The effect of viscous dissipation on the thermal boundary-layer is seen to be reverse after a fixed distance from the wall, which is very strange in nature and is the result of a reverse flow. The finding of this paper is unique and may be useful for future research on nanofluid.

scholarly journals Quantitative Perfusion Measurements in a Novel Large Animal Stroke Model

2021 ◽  
Author(s):  
◽  
Alexandra King
Keyword(s):  
Animal Model ◽  
Cause Of Death ◽  
Vasogenic Edema ◽  
Measurement Techniques ◽  
Future Research ◽  
Large Animal ◽  
Dce Mri ◽  
Post Stroke ◽  
Perfusion Measurement ◽  
Parameter Values

<p><b>Stroke is a leading cause of death worldwide [1], and is the third leading cause of death and the leading cause of serious adult disability in New Zealand[2]. The aim of this project was to quantify perfusion changes in the brains of 20 sheep that underwent a novel surgical model of transient ischemic stroke. The sheep, with its large, gyrencephalic brain, presents a promising, potential animal model for stroke that could help to bridge the historical gap in translational research in stroke therapies [3]. However, we require that an animal model can replicate human patterns of disease in order for it to be a meaningful model for research into potential stroke therapies for humans. It was this replication of human patterns of disease, in terms of perfusion, thatwas under investigation in this project. Dynamic Contrast Enhanced (DCE) MRI images were obtained from each animal before stroke, and at 24 hours, 3 days, 6 days, and 28 days post-stroke. It was found that perfusion from the DCE-MRI series was quantifiable using the extended Tofts model in the form of the parameters Ktrans, ve and vp. The parameter values calculated from this project replicate known human patternsof disease in terms of global Ktrans changes in the affected hemisphere [4], which were found to increase by more than 60% in the stroke hemisphere,replicating the increased permeability following blood brain barrier breakdown.</b></p> <p>In manually selected regions of cytotoxic and vasogenic edema, it was found that the estimated parameters in these regions replicated known perfusionchanges in these types of edema in humans [5]. Finally, the peak post-stroke permeability time point, as determined by Ktrans, was found to align exactlywith when we would expect vasogenic edema, a type of cerebral swelling that causes increased barrier permeability, to dominate in humans [5].</p> <p>This thesis is the first time these DCE-MRI datasets have been analysed, and there remains a wealth of physiological and MRI data available forthis animal cohort. Avenues for future research include investigation into perfusion-diffusion mismatch in this animal model, further consideration ofindividual animal characteristics in analysis, and use of these results as a point of comparison for future research into pharmaceutical agents for treatment ofstroke, and in new non-contrast perfusion measurement techniques.</p>

scholarly journals Social Capital on Social Media—Concepts, Measurement Techniques and Trends in Operationalization

Information ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 515 ◽  
Author(s):  
Flora Poecze ◽  
Christine Strauss
Keyword(s):  
Social Capital ◽  
Social Media ◽  
Measurement Techniques ◽  
Research Area ◽  
Future Research ◽  
Scientific Publications ◽  
Media Usage ◽  
Individual Social Capital ◽  
Social Media Platforms ◽  
Research Domain

The introduction of the Web 2.0 era and the associated emergence of social media platforms opened an interdisciplinary research domain, wherein a growing number of studies are focusing on the interrelationship of social media usage and perceived individual social capital. The primary aim of the present study is to introduce the existing measurement techniques of social capital in this domain, explore trends, and offer promising directions and implications for future research. Applying the method of a scoping review, a set of 80 systematically identified scientific publications were analyzed, categorized, grouped and discussed. Focus was placed on the employed viewpoints and measurement techniques necessary to tap into the possible consistencies and/or heterogeneity in this domain in terms of operationalization. The results reveal that multiple views and measurement techniques are present in this research area, which might raise a challenge in future synthesis approaches, especially in the case of future meta-analytical contributions.

Resilience of firefighters exposed to potentially traumatic events: a literature review

2020 ◽  
Vol 9 (2) ◽  
pp. 217-232
Author(s):  
Vanessa Laureys ◽  
Marleen Easton
Keyword(s):  
Literature Review ◽  
Measurement Techniques ◽  
Traumatic Events ◽  
Well Being ◽  
Research Field ◽  
Empirical Literature ◽  
Future Research ◽  
Cross Sectional ◽  
Content Type ◽  
Potentially Traumatic Events

PurposeThe purpose of this study is to explore the empirical literature on the resilience of firefighters related to potentially traumatic events (PTE). This paper identifies how resilience is defined in this particular research field, reveals trends in applied research methods and examines the main topics addressed in previous research.Design/methodology/approachWeb of Science, PsycARTICLES and Google Scholar databases were searched, as well as a secondary manual screening of the reference lists of all the selected studies and Dutch academic journals. Based on this review, 54 empirical articles were included in the current paper.FindingsFirstly, this paper revealed that there is no consensus in how to define the concept of resilience in this specific research area. A second observation was that most of the selected studies used a quantitative, cross-sectional research design. Finally, the 54 empirical studies provided insights on six topics: the role of the organization, demographic factors, personal characteristics, coping strategies, social support and the reactions of firefighters in the aftermath of PTE. Comparing the empirical results was challenged by the different interpretations and denominations of the concept of resilience and the myriad of measurement techniques applied across the selected articles.Originality/valueThis literature review discovered some promising avenues for future research regarding resilience of firefighters. Moreover, it demonstrated that studying resilience is particularly interesting as the identification of supporting factors leads to a better understanding of how to enhance the well-being, job satisfaction and job performance of firefighters.

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