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"When I use a word, it means whatever I want it to mean": Humpty Dumpty in Alice's Adventures Through The Looking Glass, Lewis Carroll. "Digital twin" is currently a term applied in a wide variety of ways. Some differences are variations from sector to sector, but definitions within a sector can also vary significantly. Within engineering, claims are made regarding the benefits of using digital twinning for design, optimisation, process control, virtual testing, predictive maintenance, and lifetime estimation. In many of its usages, the distinction between a model and a digital twin is not made clear. The danger of this variety and vagueness is that a poor or inconsistent definition and explanation of a digital twin may lead people to reject it as just hype, so that once the hype and the inevitable backlash are over the final level of interest and use (the "plateau of productivity") may fall well below the maximum potential of the technology. The basic components of a digital twin (essentially a model and some data) are generally comparatively mature and well-understood. Many of the aspects of using data in models are similarly well-understood, from long experience in model validation and verification and from development of boundary, initial and loading conditions from measured values. However, many interesting open questions exist, some connected with the volume and speed of data, some connected with reliability and uncertainty, and some to do with dynamic model updating. In this paper we highlight the essential differences between a model and a digital twin, outline some of the key benefits of using digital twins, and suggest directions for further research to fully exploit the potential of the approach. [ABSTRACT FROM AUTHOR]

Commercially available compression garments (CGs) demonstrate the enhanced recovery from exercise in some, but not all studies. It is possible that in some cases the degree of compression pressure (ComP) exerted is not sufficient to produce any physiological benefit. The aim of this investigation was to identify the levels of ComP exerted by commercially available CGs. This study was composed of two parts. In part A 50 healthy, physically active individuals ( n = 26 male, n = 24 female) were fitted with CGs according to manufacturer's guidelines. ComP was measured in participants standing in the anatomical position with a pressure measurement device inserted between the skin and the garment. Data were compared to 'ideal' pressure values proposed in the literature. In part B, ComP in three different brands of CG was compared in a population of 29 men who all wore a medium-sized garment. A one-way ANOVA indicated that there was a significant difference ( P < 0.05) between observed pressure and ideal pressure at the quadriceps for males and females and in the calf for the female population. There was no significant difference ( P > 0.05) between observed and ideal pressures in the calf of the male population. No significant differences in pressure ( P > 0.05) were observed between CG brands at the quadriceps or calf. In conclusion, a large number of individuals may not be experiencing an adequate ComP from CG, and this is true for all the three major brands of CGs tested in this investigation. [ABSTRACT FROM AUTHOR]

NPL is currently carrying out acoustic resonator experiments with the aim of determining the Boltzmann constant k with an uncertainty below 1 part in 10. In this article, the progress in our efforts to assess the uncertainty in our determination is described. The uncertainty contributions arising from dimensional, chemical, isotopic, thermal, and acoustical considerations are assessed, and it is concluded that a measurement with an uncertainty below 1 part in 10 is achievable. [ABSTRACT FROM AUTHOR]

Whole-genome genetic association studies in outbred mouse populations represent a novel approach to identifying the molecular basis of naturally occurring genetic variants, the major source of quantitative variation between inbred strains of mice. Measuring multiple phenotypes in parallel on each mouse would make the approach cost effective, but protocols for phenotyping on a large enough scale have not been developed. In this article we describe the development and deployment of a protocol to collect measures on three models of human disease (anxiety, type II diabetes, and asthma) as well as measures of mouse blood biochemistry, immunology, and hematology. We report that the protocol delivers highly significant differences among the eight inbred strains (A/J, AKR/J, BALBc/J, CBA/J, C3H/HeJ, C57BL/6 J, DBA/2 J, and LP/J), the progenitors of a genetically heterogeneous stock (HS) of mice. We report the successful collection of multiple phenotypes from 2000 outbred HS animals. The phenotypes measured in the protocol form the basis of a large-scale investigation into the genetic basis of complex traits in mice designed to examine interactions between genes and between genes and environment, as well as the main effects of genetic variants on phenotypes. [ABSTRACT FROM AUTHOR]