15,027 research outputs found
Light as an intervention to manage distressing symptoms in dementia: a literature review
This paper presents a literature review on the use of light as an intervention to manage distressing symptoms in dementia
Microstructural investigation of bonding and melting-induced rebound of HVOF sprayed Ni particles on an aluminum substrate
In this study, nickel powder was sprayed on a polished aluminum substrate using the high-velocity oxy-fuel spraying process. Detailed microstructural characterization was conducted to analyse the mechanims of splat formation, with particular attention to the changes occurring at the splat-substrate interface and the subsequent bonding behaviour due to the impact of high thermal and kinetic energy particles with a soft, low melting point substrate. Characterization was performed using scanning electron microscopy, focused ion beam microscopy, transmission electron microscopy, together with the scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. It was observed that a large number of particles had rebounded upon impact, which was correlated with the degree of substrate melting and the associated time for re-solidification. The remnant splats that adhered to the substrate surface were found to exhibit both mechanical and metallurgical bonding with the substrate. The experimental results were supported by transient finite element based thermal simulation
Microstructural evolution and bonding of HVOF sprayed Ni particles on both mild and stainless-steel substrates
In the present study, Ni powder was sprayed onto both mild and stainless-steel substrates using high-velocity oxy-fuel (HVOF) deposition to comparatively analyse the effect of substrate material properties and surface condition on splat formation. A range of microscopy techniques including scanning electron microscopy (SEM), focused ion beam (FIB) microscopy, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDX) were employed to characterize both the splat morphologies, including their cross-sectional structure, as well as the nature of the splat-substrate interface. It was shown that the majority of the particles reached the substrate surface in a partially melted form owing to the high velocity typical in the HVOF process. Despite some splat splashing observed on the stainless-steel sample, the diffusion profiles, determined by STEM-EDX line scans, revealed evidence of elemental interdiffusion at the splat-substrate interface, suggesting metallurgical bonding in this sample. It was observed that splat morphologies, their frequency of occurrence and splat-substrate bond quality are all greatly affected by the surface condition of the substrate. These microstructural observations were correlated with the thermo-mechanical characteristics of the substrates to explain the mechanisms driving splat formation. Differences in the degree of plastic deformation of the substrates due to particle impact are also discussed
Cooperation, collective action, and the archeology of large-scale societies
Archeologists investigating the emergence of large-scale societies in the past have renewed interest in examining the dynamics of cooperation as a means of understanding societal change and organizational variability within human groups over time. Unlike earlier approaches to these issues, which used models designated voluntaristic or managerial, contemporary research articulates more explicitly with frameworks for cooperation and collective action used in other fields, thereby facilitating empirical testing through better definition of the costs, benefits, and social mechanisms associated with success or failure in coordinated group action. Current scholarship is nevertheless bifurcated along lines of epistemology and scale, which is understandable but problematic for forging a broader, more transdisciplinary field of cooperation studies. Here, we point to some areas of potential overlap by reviewing archeological research that places the dynamics of social cooperation and competition in the foreground of the emergence of large-scale societies, which we define as those having larger populations, greater concentrations of political power, and higher degrees of social inequality. We focus on key issues involving the communal-resource management of subsistence and other economic goods, as well as the revenue flows that undergird political institutions. Drawing on archeological cases from across the globe, with greater detail from our area of expertise in Mesoamerica, we offer suggestions for strengthening analytical methods and generating more transdisciplinary research programs that address human societies across scalar and temporal spectra
Tunable cavity coupling of the zero phonon line of a nitrogen-vacancy defect in diamond
We demonstrate the tunable enhancement of the zero phonon line of a single
nitrogen-vacancy color center in diamond at cryogenic temperature. An open
cavity fabricated using focused ion beam milling provides mode volumes as small
as 1.24 m. In-situ tuning of the cavity resonance is achieved with
piezoelectric actuators. At optimal coupling of the full open cavity the signal
from individual zero phonon line transitions is enhanced by about a factor of
10 and the overall emission rate of the NV center is increased by 40%
compared with that measured from the same center in the absence of cavity field
confinement. This result is important for the realization of efficient
spin-photon interfaces and scalable quantum computing using optically
addressable solid state spin qubits.Comment: 11 pages Main Article + 4 pages Supplementary Info Typos fixed from
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Traumatic brain injury: Age at injury influences dementia risk after TBI
Traumatic brain injury (TBI) is increasingly recognized as a risk factor for dementia. New data provide further support for this association and demonstrate the influence of age at injury and injury severity on dementia risk after TBI, revealing that even mild TBI increases dementia risk in those aged â„65 years
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