5,898 research outputs found
The 2D/3D dynamics of wall-bounded low-Rm magnetohydrodynamic (MHD) turbulence
No full textWith this experimental study, we give evidence that the dynamics of low-Rm MHD turbulence depends on the diffusion length l_z, which corresponds to the distance over which the Lorentz force is able to diffuse momentum before it is balanced by inertia
Stone Pillars at CCC Camp, Custer County
No full text35 mm slide, two stone pillars in a field, may have held a signDrawer info: Custer; CCC Cu-RM Custer Co.Kodachrome Film CU-RM-7 Lattidaw CCC Office's Quarters Stone Pillars Across The Road RJ 5 Aug 89F0
Triangular Constellations in Flows
No full textParticles advected on the surface of a fluid can exhibit fractal clustering. The local structure of a fractal set is described by its dimension , which is the exponent of a power-law relating the mass in a ball to its radius : . It is desirable to characterise the {\em shapes} of constellations of points sampling a fractal measure, as well as their masses. The simplest example is the distribution of shapes of triangles formed by triplets of points, which we investigate for fractals generated by chaotic dynamical systems. The most significant parameter describing the triangle shape is the ratio of its area to the radius of gyration squared. We show that the probability density of has a phase transition: is independent of and approximately uniform below a critical flow compressibility , which we estimate. For the distribution appears to be described by two power laws: when , and when
The use of fillers in the Rolling Stone interview on YouTube between Pharrell and RM
No full textThis study investigates the use of fillers in spoken interactions between Pharrell and RM in a Rolling Stone interview on YouTube. Fillers, such as “uh,” “um,” “you know,” “like,” and other similar expressions, are non-lexical elements frequently found in spontaneous speech. The study aims to identify the types of fillers used, explore their communicative functions in informal discourse, and compare their usage between a native English speaker (Pharrell Williams) and a non-native English speaker (RM/Kim Namjoon). A descriptive qualitative method was employed, and the data were analyzed using a pragmatic approach. Fillers were categorized into two distinct types: lexicalized and unlexicalized. The findings revealed that both speakers employed fillers to serve multiple communicative functions, including hesitation markers, empathizing devices, mitigating devices, editing terms, and time-creating devices. Native speakers typically used fillers more naturally and expressively, whereas non-native speakers used them more systematically to structure their speech and maintain message clarity. These variations reflected communication strategies shaped by each speaker’s linguistic background, fluency level, and language exposure. Overall, the findings highlighted the integral role of fillers in spoken discourse and offered valuable insights for language teaching, particularly in the context of intercultural communication
Exact two-dimensionalization of low-magnetic-Reynolds-number flows subject to a strong magnetic field
No full textWe investigate the behavior of flows, including turbulent flows, driven by a horizontal body-force and subject to a vertical magnetic field, with the following question in mind: for very strong applied magnetic field, is the flow mostly two-dimensional, with remaining weak three-dimensional fluctuations, or does it become exactly 2D, with no dependence along the vertical? We restrict attention to low-magnetic-Reynolds number (Rm) flow. Because liquid metals have low magnetic Prandtl number, such low- flows can have a kinetic Reynolds number as large as one million and therefore be strongly turbulent. We first focus on the quasi-static approximation, i.e. the asymptotic limit of vanishing magnetic Reynolds number Rm << 1: we prove that the flow becomes exactly 2D asymptotically in time, regardless of the initial condition and provided the interaction parameter N is larger than a threshold value. We call this property absolute two-dimensionalization: the attractor of the system is necessarily a (possibly turbulent) 2D flow. We then consider the full-magnetohydrodynamic equations and we prove that, for low enough Rm and large enough N, the flow becomes exactly two-dimensional in the long-time limit provided the initial vertically-dependent perturbations are infinitesimal. We call this phenomenon linear two-dimensionalization: the (possibly turbulent) 2D flow is an attractor of the dynamics, but it is not necessarily the only attractor of the system. Some 3D attractors may also exist and be attained for strong enough initial 3D perturbations. These results shed some light on the existence of a dissipative anomaly for magnetohydrodynamic flows subject to a strong external magnetic field
The Decay of Wall Bounded MHD Turbulence at Low RM
No full textWe have developed a new spectral method to simulate flows with very fine boundary layers present. We apply it to calculate the evolution of freely decaying MHD turbulence between isolating walls. By comparison them with results obtained in fully periodic domain we quantify the influence of the channel walls on the character of freely decaying MHD turbulence
Specialist 'restoration mortars': a comparison of the physical properties ot two stone repair materials
No full textChimpanzee accumulative stone throwing
No full textThe authors would like to thank the Max Planck Society and Krekeler Foundation for generous funding of the Pan African Programme.The study of the archaeological remains of fossil hominins must rely on reconstructions to elucidate the behaviour that may have resulted in particular stone tools and their accumulation. Comparatively, stone tool use among living primates has illuminated behaviours that are also amenable to archaeological examination, permitting direct observations of the behaviour leading to artefacts and their assemblages to be incorporated. Here, we describe newly discovered stone tool-use behaviour and stone accumulation sites in wild chimpanzees reminiscent of human cairns. In addition to data from 17 mid- to long-term chimpanzee research sites, we sampled a further 34 Pan troglodytes communities. We found four populations in West Africa where chimpanzees habitually bang and throw rocks against trees, or toss them into tree cavities, resulting in conspicuous stone accumulations at these sites. This represents the first record of repeated observations of individual chimpanzees exhibiting stone tool use for a purpose other than extractive foraging at what appear to be targeted trees. The ritualized behavioural display and collection of artefacts at particular locations observed in chimpanzee accumulative stone throwing may have implications for the inferences that can be drawn from archaeological stone assemblages and the origins of ritual sites.Peer reviewe
Educational programs for implementing ultrasound guided peripheral intravenous catheter insertion in emergency departments: A systematic integrative literature review
No full textBackground: Ultrasound-guided peripheral intravenous catheter insertion has been identified as an effective method to improve the success rate of cannulation, thereby improving patient experience. However, learning this new skill is complex, and involves training clinicians from a variety of backgrounds. The aim of this study was to appraise and compare literature on educational methods in the emergency setting used to support ultrasound guided peripheral intravenous catheter insertion by different clinicians, and how effective these current methods are. Review methods: A systematic integrative review was undertaken using Whittemore and Knafl's five stage approach. The Mixed Methods Appraisal Tool was used to assess the quality of the studies. Results: Forty-five studies met the inclusion criteria, with five themes identified. These were: the variety of educational methods and approaches; the effectiveness of the different educational methods; barriers and facilitators of education; clinician competency assessments and pathways; clinician confidence assessment and pathways. Conclusions: This review demonstrates that a variety of educational methods are being used in successfully training emergency department clinicians in using ultrasound guidance for peripheral intravenous catheter insertion. Furthermore, this training has resulted in safer and more effective vascular access. However, it is evident that there is a lack of consistency of formalised education programs available. A standardised formal education program and increased availability of ultrasound machines in the emergency department will ensure consistent practices are maintained, retained, therefore leading to safer practice as well as more satisfied patients.Full Tex
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Ruling out dominant electron scattering in Little Red Dots’ Rosetta Stone using multiple hydrogen lines
No full textABSTRACT Most little red dots (LRDs) hosting active galactic nuclei (AGNs) show broad emission, which recent studies ascribe to scattering off free electrons within an ionized medium embedding the broad-line region (BLR), rather than directly from the BLR itself. If correct, this model would imply intrinsically narrower broad line widths, leading to black hole masses that are up to two orders of magnitude smaller than what is inferred when assuming that the whole broad line emission comes from the BLR. To test this, we present a joint analysis of multiple hydrogen recombination lines in the ‘Rosetta Stone’ AGNs, the brightest known LRD at z = 2.26. We show that , , and have different spectral profiles, which is inconsistent with the predictions of the simple scattering scenario. Additionally, we test a variety of exponential models and show that none of them can simultaneously reproduce all three line profiles with physically plausible parameters. The inadequacy of these models for the Rosetta Stone implies that the scenario of electron scattering by an ionized medium embedding the BLR is not universally applicable to LRDs and AGNs, and therefore provides a counterexample to the claim of a universal and systematic overestimation of black hole masses
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