689 research outputs found
The effectiveness of client participation in the communication of test results in group counseling.
The effectiveness of client participation in the communication of test results in group counseling
A new methodology for the quantitative visualization of coherent flow structures in alluvial channels using multibeam echo-sounding (MBES)
In order to investigate the interactions between turbulence and suspended sediment transport in natural aqueous environments, we ideally require a technique that allows simultaneous measurement of fluid velocity and sediment concentration for the whole flow field. Here, we report on development of a methodology using the water column acoustic backscatter signal from a multibeam echo sounder to simultaneously quantify flow velocities and sediment concentrations. The application of this new technique is illustrated with reference to flow over the leeside of an alluvial sand dune, which allows, for the first time in a field study, quantitative visualization of large-scale, whole flow field, turbulent coherent flow structures associated with the dune leeside that are responsible for suspending bed sediment. This methodology holds great potential for use in a wide range of aqueous geophysical flows
Recommended from our members
Building a Better Description
Universally practiced across the disciplines, description is also consistently devalued or overlooked. In this introduction to the special issue "Description Across Disciplines," Sharon Marcus, Heather Love, and Stephen Best propose that description is a critical practice more complex (and less contradictory) than its detractors have taken it to be. They argue that turning critical attention toward description’s nuances gives us access to the ways that scholars conventionally assign and withhold value and prestige. The authors set forth a number of principles (using their contributors’ essays as a guide) toward the end of "building a better description.
The influence of flow discharge variations on the morphodynamics of a diffluence-confluence unit on a large river: Impacts of discharge variation on a diffluence-confluence unit
© 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd. Bifurcations are key geomorphological nodes in anabranching and braided fluvial channels, controlling local bed morphology, the routing of sediment and water, and ultimately defining the stability of their associated diffluence–confluence unit. Recently, numerical modelling of bifurcations has focused on the relationship between flow conditions and the partitioning of sediment between the bifurcate channels. Herein, we report on field observations spanning September 2013 to July 2014 of the three-dimensional flow structure, bed morphological change and partitioning of both flow discharge and suspended sediment through a large diffluence–confluence unit on the Mekong River, Cambodia, across a range of flow stages (from 13 500 to 27 000 m 3 s −1 ). Analysis of discharge and sediment load throughout the diffluence–confluence unit reveals that during the highest flows (Q = 27 000 m 3 s −1 ), the downstream island complex is a net sink of sediment (losing 2600 ± 2000 kg s −1 between the diffluence and confluence), whereas during the rising limb (Q = 19 500 m 3 s −1 ) and falling limb flows (Q = 13 500 m 3 s −1 ) the sediment balance is in quasi-equilibrium. We show that the discharge asymmetry of the bifurcation varies with discharge and highlight that the influence of upstream curvature-induced water surface slope and bed morphological change may be first-order controls on bifurcation configuration. Comparison of our field data to existing bifurcation stability diagrams reveals that during lower (rising and falling limb) flow the bifurcation may be classified as unstable, yet transitions to a stable condition at high flows. However, over the long term (1959–2013) aerial imagery reveals the diffluence–confluence unit to be fairly stable. We propose, therefore, that the long-term stability of the bifurcation, as well as the larger channel planform and morphology of the diffluence–confluence unit, may be controlled by the dominant sediment transport regime of the system. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd
Extreme flood-driven fluvial bank erosion and sediment loads: direct process measurements using integrated Mobile Laser Scanning (MLS) and hydro-acoustic techniques: Direct measurement of flood-driven erosion using MLS and MBES
Copyright © 2016 John Wiley & Sons, Ltd. This methods paper details the first attempt at monitoring bank erosion, flow and suspended sediment at a site during flooding on the Mekong River induced by the passage of tropical cyclones. We deployed integrated mobile laser scanning (MLS) and multibeam echo sounding (MBES), alongside acoustic Doppler current profiling (aDcp), to directly measure changes in river bank and bed at high (~0.05 m) spatial resolution, in conjunction with measurements of flow and suspended sediment dynamics. We outline the methodological steps used to collect and process this complex point cloud data, and detail the procedures used to process and calibrate the aDcp flow and sediment flux data. A comparison with conventional remote sensing methods of estimating bank erosion, using aerial images and Landsat imagery, reveals that traditional techniques are error prone at the high temporal resolutions required to quantify the patterns and volumes of bank erosion induced by the passage of individual flood events. Our analysis reveals the importance of cyclone-driven flood events in causing high rates of erosion and suspended sediment transport, with a c. twofold increase in bank erosion volumes and a fourfold increase in suspended sediment volumes in the cyclone-affected wet season. Copyright © 2016 John Wiley & Sons, Ltd
Recommended from our members
Surface Reading: An Introduction
In the text-based disciplines, psychoanalysis and Marxism have had a major influence on how we read, and this has been expressed most consistently in the practice of symptomatic reading, a mode of interpretation that assumes that a text's truest meaning lies in what it does not say, describes textual surfaces as superfluous, and seeks to unmask hidden meanings. For symptomatic readers, texts possess meanings that are veiled, latent, all but absent if it were not for their irrepressible and recurring symptoms. Noting the recent trend away from ideological demystification, this essay proposes various modes of "surface reading" that together strive to accurately depict the truth to which a text bears witness. Surface reading broadens the scope of critique to include the kinds of interpretive activity that seek to understand the complexity of literary surfaces---surfaces that have been rendered invisible by symptomatic reading
Topical and Ingested Cooling Methodologies for Endurance Exercise Performance in the Heat
This systematic review and meta-analysis aimed to assess studies which have investigated cooling methodologies, their timing and effects, on endurance exercise performance in trained athletes (Category 3; VO2max ≥ 55 mL·kg·min−1) in hot environmental conditions (≥28 °C). Meta-analyses were performed to quantify the effects of timings and methods of application, with a narrative review of the evidence also provided. A computer-assisted database search was performed for articles investigating the effects of cooling on endurance performance and accompanying physiological and perceptual responses. A total of 4129 results were screened by title, abstract, and full text, resulting in 10 articles being included for subsequent analyses. A total of 101 participants and 310 observations from 10 studies measuring the effects of differing cooling strategies on endurance exercise performance and accompanying physiological and perceptual responses were included. With respect to time trial performance, cooling was shown to result in small beneficial effects when applied before and throughout the exercise bout (Effect Size: −0.44; −0.69 to −0.18), especially when ingested (−0.39; −0.60 to −0.18). Current evidence suggests that whilst other strategies ameliorate physiological or perceptual responses throughout endurance exercise in hot conditions, ingesting cooling aids before and during exercise provides a small benefit, which is of practical significance to athletes’ time trial performance
Introduction to methods for analysis of combined individual and aggregate social science data
The lecture notes from this workshop provide an introduction to a new class of multilevel models – termed hierarchical related regressions (HRR) – for estimating individual-level associations using a combination of aggregate (group level) and individual-level data. HRR differs from other methods by enabling analysts to model individual and aggregate data simultaneously, while including information on the dependent variable at the aggregate level (e.g. constituency election results), and data from aggregation units not available at the individual level (e.g. census data from all constituencies or output areas in the country). The workshop will also discuss HRR as a method of improving ecological inference (analyses that aim to make inference on the relationship between individual-level quantities using aggregate data). The HRR models combine features of standard ecological regression models for aggregate data and multilevel models for clustered individual-level data, and have been shown to reduce bias and improve precision in many situations
The optical spectra of X-shaped radio galaxies
X-shaped radio galaxies are defined by their peculiar large-scale radio
morphology. In addition to the classical double-lobed structure they have a
pair of low-luminosity wings that straddles the nucleus at almost right angles
to the active lobes, thus giving the impression of an 'X'. In this paper we
study for the first time the optical spectral properties of this object class
using a large sample (~50 sources). We find that the X-shaped radio population
is composed roughly equally of sources with weak and strong emission line
spectra, which makes them, in combination with the well-known fact that they
preferentially have radio powers intermediate between those of Fanaroff-Riley
type I (FR I) and type II (FR II) radio galaxies, the archetypal transition
population. We do not find evidence in support of the proposition that the
X-shape is the result of a recent merger: X-shaped radio sources do not have
unusually broad emission lines, their nuclear environments are in general not
dusty, and their host galaxies do not show signs of enhanced star formation.
Instead, we observe that the nuclear regions of X-shaped radio sources have
relatively high temperatures. This finding favours models, which propose that
the X-shape is the result of an overpressured environment.Comment: 12 pages, 8 figures, accepted by MNRA
- …