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Our fascination with parietal art (also known as cave art), as with most prehistoric artifacts, often lies in the mystery of its origins, and the fact, astonishingly, of its enduring presence; it appears to us in images that speak through time. This auratic allure is obscured, however, by the uncanny conditions in which we now encounter these images: as most of the original sites are closed to the public in order to preserve them, we find exceptionally crafted replicas constructed in their place. Here, Veber examines whether images still carry through time.

3D printing has seen a recent massive diffusion for several applications, not least the field of Cultural Heritage. Being used for different purposes, such as study, analysis, conservation or access in museum exhibitions, 3D printed replicas need to undergo a process of validation also in terms of metrical precision and accuracy. The Laboratory of Photogrammetry of Iuav University of Venice has started several collaborations with Italian museum institutions firstly for the digital acquisition and then for the physical reproduction of objects of historical and artistic interest. The aim of the research is to analyse the metric characteristics of the printed model in relation to the original data, and to optimize the process that from the survey leads to the physical representation of an object. In fact, this could be acquired through different methodologies that have different precisions (multi-image photogrammetry, TOF laser scanner, triangulation based laser scanner), and it always involves a long processing phase. It should not be forgotten that the digital data have to undergo a series of simplifications, which, on one hand, eliminate the noise introduced by the acquisition process, but on the other one, they can lead to discrepancies between the physical copy and the original geometry. In this paper we will show the results obtained on a small archaeological find that was acquired and reproduced for a museum exhibition intended for blind and partially sighted people.

Extracting latent nonlinear dynamics from observed time-series data is important for understanding a dynamic system against the background of the observed data. A state space model is a probabilistic graphical model for time-series data, which describes the probabilistic dependence between latent variables at subsequent times and between latent variables and observations. Since, in many situations, the values of the parameters in the state space model are unknown, estimating the parameters from observations is an important task. The particle marginal Metropolis–Hastings (PMMH) method is a method for estimating the marginal posterior distribution of parameters obtained by marginalization over the distribution of latent variables in the state space model. Although, in principle, we can estimate the marginal posterior distribution of parameters by iterating this method infinitely, the estimated result depends on the initial values for a finite number of times in practice. In this paper, we propose a replica exchange particle marginal Metropolis–Hastings (REPMMH) method as a method to improve this problem by combining the PMMH method with the replica exchange method. By using the proposed method, we simultaneously realize a global search at a high temperature and a local fine search at a low temperature. We evaluate the proposed method using simulated data obtained from the Izhikevich neuron model and Lévy-driven stochastic volatility model, and we show that the proposed REPMMH method improves the problem of the initial value dependence in the PMMH method, and realizes efficient sampling of parameters in the state space models compared with existing methods.

Quantitative unit operation models for the optimization and refinement of modern late-stage biopharmaceutical drug manufacturing processes have recently attracted increasing attention. The supplementary benefits of these models include increased process robustness and control in combination with a more stringent design of the bioprocess due to a reduced number of exploratory experiments. In addition to unit operations, further efforts also focus on digital bioprocess replicas, which are straightforward combinations of unit operation and process models from inoculum to the fill and finish phase. In this review, we shed more light on digital bioprocess replicas in addition to standard unit operation models and discuss their strengths and weaknesses. We comment on the current usage of these approaches for late stage processes and outline the associated benefits, challenges and limitations. Modeling and statistics approaches give a detailed overview of individual unit operations in biopharmaceutical processes.A fully digital bioprocess replica has significant benefits but also challenges.Modeling approaches play an important role in quality by design principles.Machine learning and artificial intelligence approaches might also be integrated into the future design of bioprocesses.Molecular models and molecular understanding are important for refined biopharmaceutical manufacturing processes and root-cause analysis.

With the rapid development of mixed reality (MR) technology, many compact, lightweight, and powerful devices suitable for remote collaboration, such as MR headsets, hand trackers, and 3D cameras, become readily available, providing hardware and software support for remote collaboration. Consequently, exploring MR technologies for remote collaboration on physical industry tasks is becoming increasingly worthwhile. In many complex production scenarios, such as assembly tasks, significant gains can be achieved by having remote experts assist local workers to manipulate objects in local workspaces. However, it can be challenging for a remote expert to carry out effective spatial reference and action demonstration in a local scene. Sharing 3D stereoscopic scenes can provide depth perception and support remote experts to move and explore a local user’s environment freely. Previous studies have demonstrated that gesture-based interaction is natural and intuitive, and interaction based on virtual replicas can provide clear guidance, especially for industrial physical tasks. In this study, we develop an MR remote collaboration system that shares the stereoscopic scene of the local workspace by using real-time 3D video. This system combines gesture cues and virtual replicas in a complementary manner to support the remote expert to create augmented reality (AR) guidance for the local worker naturally and intuitively in the virtual reality immersive space. A formal user study was performed to explore the effects of two different modalities interface in industrial assembly tasks: our novel method of using the combination of virtual replicas and gesture cues in the 3D video (VG3DV), and a method similar to the popular method currently of using gesture cues in the 3D video (G3DV). We found that using the VG3DV can significantly improve the performance and user experience of MR remote collaboration in industrial assembly tasks. Finally, some conclusions and future research directions were given.

In this paper, we focus on the significance of remote collaboration using virtual replicas, avatar, and gesture on a procedural task in industry; thus, we present a Virtual Reality (VR)/Spatial Augmented Reality (SAR) remote collaboration system, BeHere, based on 3D virtual replicas and sharing gestures and avatar. BeHere enables a remote expert in VR to guide a local worker in real-time to complete a procedural task in the real-world. For the remote VR site, we construct a 3D virtual environment using virtual replicas, and the user can manipulate them by using gestures in an intuitive interaction and see their partners’ 3D virtual avatar. For the local site, we use SAR to enable the local worker to see instructions projected onto the real-world based on the shared virtual replicas and gestures. We conducted a formal user study to evaluate the prototype system in terms of performance, social presence, workload, and ranking and user preference. We found that the combination of visual cues of gestures, avatar, and virtual replicas plays a positive role in improving user experience, especially for remote VR users. More significantly, our study provides useful information and important design implications for further research on the use of gesture-, gaze- and avatar-based cues as well as virtual replicas in VR/AR remote collaboration on a procedural task in industry.

Objectives This study compared the silicone replica method with swept-source optical coherence tomography (SS-OCT) to analyze marginal adaptation and investigated the effect of the light incidence angle of SS-OCT on measurement precision. Materials and methods A typodont-prepared mandibular right first molar was scanned using an intraoral scanner (Trios 3). Fourteen crowns were fabricated from CAD/CAM resin blocks (Katana Avencia P) using a 5-axis milling machine (DWX-50). Marginal adaptation at the buccal, lingual, mesial, and distal points was assessed using the silicone replica method and SS-OCT at light incidence angles of 60°, 75°, and 90°. Statistical comparisons were performed using two-way analysis of variance (ANOVA) and t-tests with Bonferroni correction, and t-tests at a significance level of 0.05. Results At 60°, SS-OCT showed significantly larger marginal discrepancies than the silicone replica method at the buccal, lingual, and mesial points ( p  < 0.05). At 75°, only the lingual point showed a significantly larger value than the silicone replica method ( p  < 0.05). At 90°, no significant differences were observed between the SS-OCT and silicone replica methods ( p  > 0.05). Marginal discrepancy values increased as the angle changed from 90° to 75° to 60°, with significant differences between 60° and 75° and between 60° and 90° at the buccal and lingual points ( p  < 0.05). Conclusions SS-OCT is a viable alternative to the silicone replica method for assessing marginal adaptation at an incidence angle of 90 °. Clinical relevance SS-OCT, a non-invasive method, has the potential to be applied clinically for evaluating marginal fit in indirect restorations in vivo.

Groundwater inrush is a hazard that always occurs during underground mining. Grouting is one of the most effective processes to seal underground water inflow for hazard prevention. In this study, grouting experiments are conducted by using a visualized transparent single‐fracture replica with plane roughness. Image processing and analysis are performed to investigate the thermo–hydro–mechanical coupling effect on the grouting diffusion under coal mine flowing water conditions. The results show that higher ambient temperature leads to shorter initial gel time of chemical grout and leads to a better relative sealing efficiency in the case of a lower flow rate. However, with a higher water flow rate, the relative sealing efficiency is gradually reduced under higher temperature conditions. The grouting pressure, the seepage pressure, and the temperature are measured. The results reveal that the seepage pressure shows a positive correlation with the grouting pressure, while the temperature change shows a negative correlation with the seepage pressure and the grouting pressure. The “equivalent grouting point offset” effect of grouting shows an eccentric elliptical diffusion with larger grouting distance and width under lower temperature conditions. Higher temperature leads to a better relative sealing efficiency with a slow flow rate. Temperature change shows a negative correlation with the seepage pressure and the grouting pressure. The “equivalent grouting point offset” effect of grouting shows an eccentric elliptical propagation. Highlights Higher temperature leads to a better relative sealing efficiency with a slow flow rate. Seepage pressure shows a positive correlation with grouting pressure. Temperature change shows a negative correlation with seepage pressure and grouting pressure. Small breakthrough holes are formed and the diffusion interface is shifted from the center, resulting in the “equivalent grouting point offset” effect.

Most of the world's bacteria exist in robust, sessile communities known as biofilms, ubiquitously adherent to environmental surfaces from ocean floors to human teeth and notoriously resistant to antimicrobial agents. We report the surprising observation that Bacillus subtilis biofilm colonies and pellicles are extremely non-wetting, greatly surpassing the repellency of Teflon toward water and lower surface tension liquids. The biofilm surface remains nonwetting against up to 80% ethanol as well as other organic solvents and commerical biocides across a large and clinically important concentration range. We show that this property limits the penetration of antimicrobial liquids into the biofilm, severely compromising their efficacy. To highlight the mechanisms of this phenomenon, we performed experiments with mutant biofilms lacking ECM components and with functionalized polymeric replicas of biofilm microstructure. We show that the nonwetting properties are a synergistic result of ECM composition, multiscale roughness, reentrant topography, and possibly yet other factors related to the dynamic nature of the biofilm surface. Finally, we report the impenetrability of the biofilm surface by gases, implying defense capability against vapor-phase antimicrobials as well. These remarkable properties of B. subtilis biofilm, which may have evolved as a protection mechanism against native environmental threats, provide a new direction in both antimicrobial research and bioinspired liquid-repellent surface paradigms.