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We present simultaneous two-dimensional measurements of the velocity and buoyancy fields on a central vertical plane in two-dimensional line plumes: a free plume distant from vertical boundaries and a wall plume, adjacent to a vertical wall. Data are presented in both an Eulerian and a plume coordinate system that follow the instantaneous turbulent/non-turbulent interface (TNTI) of the plume. We present measurements in both coordinate systems and compare the entrainment in the two flows. We find that the value of the entrainment coefficient in the wall plume is greater than half that of the free plume. The reduction in entrainment is investigated by considering a decomposition of the entrainment coefficient based on the mean kinetic energy where the relative contributions of turbulent production, buoyancy and viscous terms are calculated. The reduced entrainment is also investigated by considering the statistics of the TNTI and the conditional vertical transport of the ambient and engulfed fluid. We show that the wall shear stress is non-negligible and that the free plume exhibits significant meandering. The effect of the meandering on the entrainment process is quantified in terms of the stretching of the TNTI where it is shown that the length of the TNTI is greater in the free plume and, further, the relative vertical transport of the engulfed ambient fluid is observed to be 15 % greater in the free plume. Finally, the turbulent velocity and buoyancy fluctuations, Reynolds stresses and the turbulent buoyancy fluxes are presented in both coordinate systems.
We study the dynamical system of a two-dimensional, forced, stratified mixing layer at finite Reynolds number
, and Prandtl number
. We consider a hyperbolic tangent background velocity profile in the two cases of hyperbolic tangent and uniform background buoyancy stratifications, in a domain of fixed, finite width and height. The system is forced in such a way that these background profiles are a steady solution of the governing equations. As is well known, if the minimum gradient Richardson number of the flow,
, is less than a certain critical value
, the flow is linearly unstable to Kelvin–Helmholtz instability in both cases. Using Newton–Krylov iteration, we find steady, two-dimensional, finite-amplitude elliptical vortex structures – i.e. ‘Kelvin–Helmholtz billows’ – existing above
. Bifurcation diagrams are produced using branch continuation, and we explore how these diagrams change with varying
. In particular, when
is sufficiently high we find that finite-amplitude Kelvin–Helmholtz billows exist when
for the background flow, which is linearly stable by the Miles–Howard theorem. For the uniform background stratification, we give a simple explanation of the dynamical system, showing the dynamics can be understood on a two-dimensional manifold embedded in state space, and demonstrate the cases in which the system is bistable. In the case of a hyperbolic tangent stratification, we also describe a new, slow-growing, linear instability of the background profiles at finite
, which complicates the dynamics.
We compared systematic and random survey techniques to estimate breeding population sizes of burrow-nesting petrel species on Marion Island. White-chinned (Procellaria aequinoctialis) and blue (Halobaena caerulea) petrel population sizes were estimated in systematic surveys (which attempt to count every colony) in 2009 and 2012, respectively. In 2015, we counted burrows of white-chinned, blue and great-winged (Pterodroma macroptera) petrels within 52 randomized strip transects (25 m wide, total 144 km). Burrow densities were extrapolated by Geographic Information System-derived habitat attributes (geology, vegetation, slope, elevation, aspect) to generate island-wide burrow estimates. Great-winged petrel burrows were found singly or in small groups at low densities (2 burrows ha−1); white-chinned petrel burrows were in loose clusters at moderate densities (3 burrows ha−1); and blue petrel burrows were in tight clusters at high densities (13 burrows ha−1). The random survey estimated 58% more white-chinned petrels but 42% fewer blue petrels than the systematic surveys. The results suggest that random transects are best suited for species that are widely distributed at low densities, but become increasingly poor for estimating population sizes of species with clustered distributions. Repeated fixed transects provide a robust way to monitor changes in colony density and area, but might fail to detect the formation/disappearance of new colonies.
A survey of Antarctic toothfish (Dissostichus mawsoni) was conducted in the northern Ross Sea region during the winter of 2016 to document the timing and location of spawning activity, to collect biological information about reproductive status during the spawning season and to look for temporal signals in biological data from D. mawsoni that may indicate a spawning migration of mature toothfish from the continental slope region to the northern Ross Sea region. The 58 day survey showed that spawning of D. mawsoni began on some seamounts by early July. No changes were detected between winter and summer in length, age, sex ratio or condition factor distributions for D. mawsoni in the northern Ross Sea as hypothesized following a spawning migration from the slope to the northern Ross Sea region. These results suggest that the distribution of D. mawsoni in the Ross Sea is mainly accomplished through ontogenetic migration and not annual return spawning migrations.
Cognitive behavioural therapy (CBT) is the most efficacious and effective psychological intervention for treating anxiety disorders. Behavioural techniques, in particular exposure-based techniques, are fundamental to positive outcomes. However, research suggests that these techniques are either not used or are under-used when treating anxiety disorders. This study assesses therapists’ reported use of CBT techniques in the treatment of anxiety disorders, and explores which therapist variables influence technique use. A total of 173 CBT therapists completed measures on their demographics, routine therapy practices in treating anxiety disorders, and internal states (e.g. self-esteem). These data were analysed to see how often therapists employed particular techniques and the correlates of the use of those techniques. Behavioural techniques (e.g. exposure) were the least utilized set of core CBT skills, being used less often than non-CBT techniques. The under-utilization of these key techniques was associated with greater levels of increased inhibitory anxiety amongst therapists. Supervision and therapists’ self-esteem were both positively associated with the use of non-CBT techniques. While this study established what CBT therapists purport to use in routine practice with anxious populations, further research is needed to assess the association between adherence (or lack thereof) and client outcomes, and the factors that drive non-adherence.
Key learning aims
As a result of reading this paper, the reader should:
(1)Learn about what psychotherapists report as occurring in routine care for individuals with anxiety and related disorders.
(2)Know the potential therapist traits that influence the use of CBT techniques.
(3)Gain knowledge to help explain to clients why previous therapy may not have been effective.
(4)Develop a richer understanding of what factors may influence their own therapeutic practice.
Introduction: Vasopressors are routinely utilized to treat systemic shock, a significant source of morbidity and mortality in the pediatric population. Local tissue ischemia has been classically implicated with peripheral use of these medications. However, peripheral administration (PVC) has theoretical benefits, and avoids many of the risks associated with central venous catheter (CVC) placement. There appears to be paucity of literature in pediatrics examining this subject. We conducted a systematic review investigating local tissue complications and extravasations of both PVC and CVC administration in the pediatric population. Specifically we examined the type of vasopressor used, the site used, the duration of the infusion, and finally the overall outcome for patients. Methods: A systematic search was conducted using PubMed, Embase, Cochrane, and CINAHL databases. Terms for IV administration, specific vasopressor use, complication of interest, and pediatric population were combined. We included studies that satisfied our predetermined criteria. All search results were imported into Covidence software where the primary author conducted an initial title and abstract review. Papers that met the pre-identified criteria were selected for full text review. Papers selected for full text review were independently reviewed by two of the authors. Agreement between the authors was measured utilizing a κ statistic. Results: Our search yielded 14784 results, of which 237 were assessed for full text review. The κ between the authors is pending. 13 studies were selected for final inclusion. There were 14 patients with 15 total events. 13 were from PVC use while 2 occurred with CVC's. 11 of the 13 complications associated with PVC administration occurred through extravasation, with 2 events from local ischemia. 9 children were administered dopamine, 1 norepinephrine, and 14 were on multiple vasopressors. 3/13 events were “proximal” or occurring at or above the AC or popliteal fossa while 10/13 events were “distal”. The average time to ischemic injury or extravasation peripherally was 56.1 hours with a range of 1.5 to 360 hours. 9 of the total patients did not have any long-term sequelae. One patient had toe amputations, while two others died because of illness. One CVC patient died as a result extravasation leading to asphyxiation. Conclusion: There is a lack of significant literature reporting serious adverse events related to peripheral or central administration of vasopressors in the pediatric population.
Applications of some selected elemental determinations of different catalytic materials by radioisotope excited x-ray fluorescence will be presented. The analytical method, an improved sample preparation and analysis technique were presented at the last Denver Conference (1). Data on the accuracy and precision of each of the following types of catalysts are presented. 1) Platinum catalysts (0.5 - 10% Pt) on alumina and carbon supports used for dehydrogenation, hydrohalogenation, oxidation processes, etc. 2) Palladium catalysts (0.5% - 10% Pt) on alumina and carbon supports employed for alkylation, decarbonisation, hydrogenation, etc.
Rayleigh–Bénard convection is one of the most well-studied models in fluid mechanics. Atmospheric convection, one of the most important components of the climate system, is by comparison complicated and poorly understood. A key attribute of atmospheric convection is the buoyancy source provided by the condensation of water vapour, but the presence of radiation, compressibility, liquid water and ice further complicate the system and our understanding of it. In this paper we present an idealized model of moist convection by taking the Boussinesq limit of the ideal-gas equations and adding a condensate that obeys a simplified Clausius–Clapeyron relation. The system allows moist convection to be explored at a fundamental level and reduces to the classical Rayleigh–Bénard model if the latent heat of condensation is taken to be zero. The model has an exact, Rayleigh-number-independent ‘drizzle’ solution in which the diffusion of water vapour from a saturated lower surface is balanced by condensation, with the temperature field (and so the saturation value of the moisture) determined self-consistently by the heat released in the condensation. This state is the moist analogue of the conductive solution in the classical problem. We numerically determine the linear stability properties of this solution as a function of Rayleigh number and a non-dimensional latent-heat parameter. We also present some two-dimensional, time-dependent, nonlinear solutions at various values of Rayleigh number and the non-dimensional condensational parameters. At sufficiently low Rayleigh number the system converges to the drizzle solution, and we find no evidence that two-dimensional self-sustained convection can occur when that solution is stable. The flow transitions from steady to turbulent as the Rayleigh number or the effects of condensation are increased, with plumes triggered by gravity waves emanating from other plumes. The interior dries as the level of turbulence increases, because the plumes entrain more dry air and because the saturated boundary layer at the top becomes thinner. The flow develops a broad relative humidity minimum in the domain interior, only weakly dependent on Rayleigh number when that is high.
This paper will investigate how geographic features were recorded on maps in the eighteenth century in order to outline the construction of geographic knowledge by British mapmakers. Due to practical and economic factors, early modern cartography was a conservative practice based on source compilation and comparison. For the Pacific region especially, the paucity of first-hand observations and the conflicting nature of those observations rendered the world's largest ocean difficult to chart and prone to the retention of mythical continents, passages and islands. After a discussion of the practical and economic reasons why geographic features were difficult to revise on maps, the article focuses on a case study to show how geographic enigmas could be placed and persist. It will use Pepys Island to illustrate the ways in which a chimeric feature could become instilled in geographic parlance.
Antarctic silverfish (Pleuragramma antarctica Boulenger) are a keystone species in the Ross Sea. Silverfish eggs and larvae are abundant during spring amongst the sub-surface platelet ice in Terra Nova Bay. It is not known whether the eggs are spawned elsewhere and accumulate under the ice or whether there is mass migration of silverfish to coastal spawning sites in winter. To test the latter hypothesis, an upward-looking 67 kHz echo sounder was moored in Terra Nova Bay to observe potential silverfish migration. The echo sounder was deployed at 380 m in a seabed depth of 550 m and ran for 210 days from 15 May until 11 December 2015. Acoustic reflections consistent with silverfish were observed at depths of 230–380 m during 9–22 September. This timing is consistent with the presence of eggs typically observed in October. Adult silverfish were also detected with an echo sounder and camera deployed through the ice in McMurdo Sound on 10 November 2015. Juvenile silverfish, but not adults, were observed through the ice in Terra Nova Bay during 11–16 November 2017. This paper provides a proof of concept, showing that innovative use of acoustics may help fill important observation gaps in the life history of silverfish.
We observed pediatric S. aureus hospitalizations decreased 36% from 26.3 to 16.8 infections per 1,000 admissions from 2009 to 2016, with methicillin-resistant S. aureus (MRSA) decreasing by 52% and methicillin-susceptible S. aureus decreasing by 17%, among 39 pediatric hospitals. Similar decreases were observed for days of therapy of anti-MRSA antibiotics.
The origins of agriculture in South-west Asia is a topic of continued archaeological debate. Of particular interest is how agricultural populations and practices spread inter-regionally. Was the Arabian Neolithic, for example, spread through the movement of pastoral groups, or did ideas perhaps develop independently? Here, the authors report on recent excavations at Alshabah, one of the first Neolithic sites discovered in Northern Arabia. The site’s material culture, environmental context and chronology provide evidence suggesting that well-adapted, seasonally mobile, pastoralist groups played a key role in the Neolithisation of the Arabian Peninsula.
The term ‘mood stabiliser’ is ill-defined and lacks clinical utility. We propose a framework to evaluate medications and effectively communicate their mood stabilising properties – their acute and prophylactic efficacy across the domains of mania and depression. The standardised framework provides a common definition to facilitate research and clinical practice.
Declaration of interest
The Treatment Algorithm Group (TAG) was supported logistically by Servier who provided financial assistance with travel and accommodation for those TAG members travelling interstate or overseas to attend the meeting in Sydney (held on 18 November 2017). None of the committee were paid to participate in this project and Servier have not had any input into the content, format or outputs from this project.
It is an unfortunate fact that the Near-Middle Eastern area, which has produced its share of the world's more spectacular antiquities, and which has been the focus of archaeological activity for so many years, has supplied but little material for the radiocarbon dating project. The dearth of specimens would seem to be due to two main factors. First, the general lack of attention hitherto given by excavators to non-artifactual materials (i.e., unworked wood, grain, etc.). Second, the understandable reluctance of museum curators to submit actual specimens of artifacts as samples, since they are destroyed in the process.
Erect veldtgrass (Ehrharta erecta Lam.) is an invasive grass actively spreading in California that is capable of invading multiple habitats. Our objective is to contribute to a better understanding of the ecology, impacts, and potential for control of E. erecta in order to guide management practices. In a mixed-evergreen forest in Santa Cruz County, we measured impacts of E. erecta on native plant species richness and abundance in an observational comparison across 11 sites. Strikingly, we measured nearly four times greater total vegetation cover in plots invaded by E. erecta. However, native plants were not significantly less abundant in invaded plots than in reference plots, and native cover was not significantly predicted by E. erecta cover within invaded plots. We did, however, find evidence of change in community composition in response to E. erecta abundance. Our findings demonstrate that native species can persist in the presence of E. erecta, although the long-term impacts on populations of the perennial plants that dominate this forest understory are still unknown.
We also compared the effectiveness of mechanical (hand pulling with volunteers) and chemical (glyphosate) management methods. Twenty-two months following management treatments, we found substantial reductions in E. erecta using both mechanical and herbicide treatments, but herbicide application also produced greater reductions in native species cover and species richness. Transplanting native yerba buena [Clinopodium douglasii (Benth.) Kuntze] into management plots following treatment did not slow regrowth of E. erecta. It did, however, increase total native plant percent cover in herbicide and pull treatments, although largely by increasing C. douglasii cover. Effective management is possible using either manual or chemical removal methods; the optimal method may depend on the availability of manual labor and the sensitivity of the habitat to non-target effects on native plants.
We present the results of simulations that explore the variety of accretion flows possible in magnetic cataclysmic variables (mCVs). Our simulations evolve to equilibrium periods spanning 0.01 < Рspin/Рorb < 0.6 and the resulting flows vary from disc-fed systems at Рspin/Рorb ~ 0.01 - 0.1, to stream fed systems at Рspin/Рorb ~ 0.1 - 0.5 and systems fed from a ring at the outer edge of the white dwarf's Roche lobe at Рspin/Рorb ~ 0.6.
Michigan State University (MSU) serves a large and diverse student population, ∼ 1000 of whom take the astronomy course for non-science majors each year. Significant resources are also invested in the related astronomy lab, enrolling about half the lecture students. Although this lab is optional, the students are required to complete one lab course for their degree. In the fall of 1995, we undertook an extensive assessment of student learning in these astronomy courses.
While our fascination with understanding the past is sufficient to warrant an increased focus on synthesis, solutions to important problems facing modern society require understandings based on data that only archaeology can provide. Yet, even as we use public monies to collect ever-greater amounts of data, modes of research that can stimulate emergent understandings of human behavior have lagged behind. Consequently, a substantial amount of archaeological inference remains at the level of the individual project. We can more effectively leverage these data and advance our understandings of the past in ways that contribute to solutions to contemporary problems if we adapt the model pioneered by the National Center for Ecological Analysis and Synthesis to foster synthetic collaborative research in archaeology. We propose the creation of the Coalition for Archaeological Synthesis coordinated through a U.S.-based National Center for Archaeological Synthesis. The coalition will be composed of established public and private organizations that provide essential scholarly, cultural heritage, computational, educational, and public engagement infrastructure. The center would seek and administer funding to support collaborative analysis and synthesis projects executed through coalition partners. This innovative structure will enable the discipline to address key challenges facing society through evidentially based, collaborative synthetic research.
The ability to produce high quality beef carcasses cost-effectively in an 18-month finishing system is partly determined by the feeding regime during winter and the subsequent response to grass during the finishing period. Animals fed on grass silage throughout winter have been shown to develop fatter carcasses (Baker et al., 1985). The aim of this study was to investigate the effects of altered carcass composition at the end of a winter store period on composition at the end of a summer grazing period.