Science museum educators' views on object-based learning: The perceived importance of authenticity and touch

Museum educators play an important role in mediating visitors' museum experiences. We investigated the perspectives of science museum educators on the role of touching authentic objects and replicas in visitors' learning experiences during educational activities. We used a mixed-methods approach including surveys with 49 museum educators and interviews with 12 museum educators from several countries in Europe. Our findings indicate the importance of context when presenting museum visitors with objects. Participating museum educators based their choices for including authentic objects or replicas in educational activities more often on narrative and context than on the authenticity status of an object. In addition, educators used various definitions of authenticity, which may hinder the discussion about the topic within the field.

Root Maturation of an Immature Dens Invaginatus Despite Unsuccessful Revitalization Procedure: A Case Report and Recommendations for Educational Purposes

BACKGROUND

The clinical management of teeth with complex dens invaginatus (DI) malformations and apical periodontitis may be challenging due to the lack of routine. The aim of this case report is to describe the endodontic treatment of an immature tooth with DI and to discuss strategies for preclinical training for teeth with such malformations.

CASE REPORT

A 9-year-old male presented with an immature maxillary incisor with DI (Oehlers Type II) and apical periodontitis which was diagnosed by cone beam computed tomography (CBCT). Revitalization was initially attempted but then abandoned after failure to generate a stable blood clot. Nevertheless, considerable increase in both root length and thickness could be detected after medication with calcium hydroxide followed by root canal filling with MTA as an apical plug.

CONCLUSIONS

The endodontic management of teeth with DI requires thorough treatment planning. In immature teeth, under certain conditions, root maturation may occur even with conventional apexification procedures. From an educational perspective, different strategies including CBCT and 3D-printed transparent tooth models for visualization of the complex internal morphology and redesigned 3D-printed replica with various degrees of difficulty for endodontic training, can be used to overcome the challenges associated with endodontic treatment of such teeth.

A Prospective Study on Autotransplantation of Mandibular Third Molars With Complete Root Formation

Study Design

Autotransplantation, if possible, is a viable option for replacing a missing tooth when a donor tooth is available. The most typical tooth transplant is the transfer of a third molar to a first molar site. No immune reaction results from transplants of this nature. It restores the proprioceptive function and normal periodontal healing; thus, the patient can have a natural chewing feeling and natural biological response.

Objective

This study aims to evaluate the prognosis of autotransplanted mandibular third molar and also to evaluate the cost effectiveness of the treatment performed when compared to the other treatment modalities for prosthetic rehabilitation.

Methods

A prospective study was done in the Department of Oral & Maxillofacial Surgery, Sardar Patel Post Graduate Institute of Dental & Medical Sciences, Lucknow, UP, India, with over 20 patients to evaluate the prognosis of autotransplanted mandibular third molars with complete root formation after atraumatic extraction of first or second mandibular molar, which were randomly selected irrespective of race, sex, caste, and socio-economic status. Regular clinical and radiographical examinations were performed over a period of 1 year and the patients were assessed for pain, swelling, infection, dry socket, periodontal pocket depth, ankylosis, root resorption, tooth mobility, and level of buccal bone in relation to cementoenamel junction (CEJ).

Results

Eighteen out of 20 transplants were successful; only 2 mandibular transplants were extracted because of abnormal horizontal and axial mobility and the reason of failure was attributed to fact that the roots of transplant were short and conical and there was lack of alveolar bone height at the recipient site in one patient, while root resorption was the reason for failure of transplant in the other patient.

Conclusions

This study assessed the efficacy of autotransplantation of molars and the viability of the procedure to replace unrestorable molar teeth; it also supports the hypothesis that transplantation of a mandibular third molar for replacement of a lost or seriously damaged molar tooth could be a reasonable alternative.

3D-Printed Replica and Porcine Explants for Pre-Clinical Optimization of Endoscopic Tumor Treatment by Magnetic Targeting

Simple Summary

Animal models are often needed in cancer research but some research questions may be answered with other models, e.g., 3D replicas of patient-specific data, as these mirror the anatomy in more detail. We, therefore, developed a simple eight-step process to fabricate a 3D replica from computer tomography (CT) data using solely open access software and described the method in detail. For evaluation, we performed experiments regarding endoscopic tumor treatment with magnetic nanoparticles by magnetic hyperthermia and local drug release. For this, the magnetic nanoparticles need to be accumulated at the tumor site via a magnetic field trap. Using the developed eight-step process, we printed a replica of a locally advanced pancreatic cancer and used it to find the best position for the magnetic field trap. In addition, we described a method to hold these magnetic field traps stably in place. The results are highly important for the development of endoscopic tumor treatment with magnetic nanoparticles as the handling and the stable positioning of the magnetic field trap at the stomach wall in close proximity to the pancreatic tumor could be defined and practiced. Finally, the detailed description of the workflow and use of open access software allows for a wide range of possible uses.

Abstract

Background: Animal models have limitations in cancer research, especially regarding anatomy-specific questions. An example is the exact endoscopic placement of magnetic field traps for the targeting of therapeutic nanoparticles. Three-dimensional-printed human replicas may be used to overcome these pitfalls. Methods: We developed a transparent method to fabricate a patient-specific replica, allowing for a broad scope of application. As an example, we then additively manufactured the relevant organs of a patient with locally advanced pancreatic ductal adenocarcinoma. We performed experimental design investigations for a magnetic field trap and explored the best fixation methods on an explanted porcine stomach wall. Results: We describe in detail the eight-step development of a 3D replica from CT data. To guide further users in their decisions, a morphologic box was created. Endoscopies were performed on the replica and the resulting magnetic field was investigated. The best fixation method to hold the magnetic field traps stably in place was the fixation of loops at the stomach wall with endoscopic single-use clips. Conclusions: Using only open access software, the developed method may be used for a variety of cancer-related research questions. A detailed description of the workflow allows one to produce a 3D replica for research or training purposes at low costs.

Noise in Neurons and Synapses Enables Reliable Associative Memory Storage in Local Cortical Circuits

Neural networks in the brain can function reliably despite various sources of errors and noise present at every step of signal transmission. These sources include errors in the presynaptic inputs to the neurons, noise in synaptic transmission, and fluctuations in the neurons’ postsynaptic potentials (PSPs). Collectively they lead to errors in the neurons’ outputs which are, in turn, injected into the network. Does unreliable network activity hinder fundamental functions of the brain, such as learning and memory retrieval? To explore this question, this article examines the effects of errors and noise on the properties of model networks of inhibitory and excitatory neurons involved in associative sequence learning. The associative learning problem is solved analytically and numerically, and it is also shown how memory sequences can be loaded into the network with a biologically more plausible perceptron-type learning rule. Interestingly, the results reveal that errors and noise during learning increase the probability of memory recall. There is a trade-off between the capacity and reliability of stored memories, and, noise during learning is required for optimal retrieval of stored information. What is more, networks loaded with associative memories to capacity display many structural and dynamical features observed in local cortical circuits in mammals. Based on the similarities between the associative and cortical networks, this article predicts that connections originating from more unreliable neurons or neuron classes in the cortex are more likely to be depressed or eliminated during learning, while connections onto noisier neurons or neuron classes have lower probabilities and higher weights.

Open-Cellular Alumina Foams with Hierarchical Strut Porosity by Ice Templating: A Thickening Agent Study

Alumina replica foams were manufactured by the Schwartzwalder sponge replication technique and were provided with an additional strut porosity by a freeze-drying/ice-templating step prior to thermal processing. A variety of thickeners in combination with different alumina solid loads in the dispersion used for polyurethane foam template coating were studied. An additional strut porosity as generated by freeze-drying was found to be in the order of ~20%, and the spacings between the strut pores generated by ice-templating were in the range between 20 µm and 32 µm. In spite of the lamellar strut pore structure and a total porosity exceeding 90%, the compressive strength was found to be up to 1.3 MPa. Combining the replica process with freeze-drying proves to be a suitable method to enhance foams with respect to their surface area accessible for active coatings while preserving the advantageous flow properties of the cellular structure. A two-to-threefold object surface-to-object volume ratio of 55 to 77 mm⁻¹ was achieved for samples with 30 vol% solid load compared to 26 mm⁻¹ for non-freeze-dried samples. The freeze-drying technique allows the control of the proportion and properties of the introduced pores in an uncomplicated and predictable way by adjusting the process parameters. Nevertheless, the present article demonstrates that a suitable thickener in the dispersion used for the Schwartzwalder process is inevitable to obtain ceramic foams with sufficient mechanical strength due to the necessarily increased water content of the ceramic dispersion used for foam manufacturing.

Spatio-temporal development of cuticular ridges on leaf surfaces of Hevea brasiliensis alters insect attachment

Cuticular ridges on plant surfaces can control insect adhesion and wetting behaviour and might also offer stability to underlying cells during growth. The growth of the plant cuticle and its underlying cells possibly results in changes in the morphology of cuticular ridges and may also affect their function. We present spatial and temporal patterns in cuticular ridge development on the leaf surfaces of the model plant, Hevea brasiliensis. We have identified, by confocal laser scanning microscopy of polymer leaf replicas, an acropetally directed progression of ridges during the ontogeny of Hevea brasiliensis leaf surfaces. The use of Colorado potato beetles (Leptinotarsa decemlineata) as a model insect species has shown that the changing dimensions of cuticular ridges on plant leaves during ontogeny have a significant impact on insect traction forces and act as an effective indirect defence mechanism. The traction forces of walking insects are significantly lower on mature leaf surfaces compared with young leaf surfaces. The measured walking traction forces exhibit a strong negative correlation with the dimensions of the cuticular ridges.

Surface Topography of PDMS Replica Transferred from Various Decellularized Aortic Lumens Affects Cellular Orientation

Cells sense and respond to various surface topographies of substrates. Many types of topographical architectures have been developed for understanding cell-extracellular matrix (ECM) interactions and for their application in biomaterials. In the present study, as a topographical surface similar to native tissue, we developed a PDMS replica prepared using the transferring method of the decellularized aorta, which is an ECM assembly, and its cellular behaviors, such as orientation and elongation on it. Decellularized aortas were prepared by high hydrostatic pressure (HHP) and sodium dodecyl sulfate (SDS) methods for use as templates. Scanning electron microscopic observation of the SDS replica showed a randomly rough surface. Further, microscaled linear structures along the direction of the aortic longitudinal axis were observed on the HHP replica. These results indicated that the topographical surface of the HHP and SDS decellularized aorta could be replicated to their replicas at a microscale. Fibroblasts (NIH3T3) and endothelial cells (HUVECs) were cultured on their surfaces. Although they were randomly aligned on the SDS replica and flat surface, the high cellular alignment along with the direction of the aortic longitudinal axis was shown in the HHP replica and HHP decellularized aorta. These results suggest that the topographical structure similar to a native aorta could effectively induce the cell alignment, which is important to regulate cellular functions, and could provide important methodologies and knowledge for vascular biomaterials or culture substrates.

Comparison of the Fit of Lithium Disilicate Crowns made from Conventional, Digital, or Conventional/Digital Techniques

PURPOSE

To evaluate the fit of single crowns fabricated using conventional, digital, or cast digitization methods.

MATERIALS AND METHODS

One subject with a peg-shaped maxillary lateral incisor was selected in this study. Tooth preparation for an all-ceramic crown was performed and 10 conventional poly(vinyl siloxane) impressions, and 10 digital impressions using an intraoral scanner were made. Each working cast was scanned using a laboratory scanner and an intraoral scanner. Four groups were tested Group 1: conventional impressions. Group 2: cast laboratory scans. Group 3: cast scans using intraoral scanner. Group 4: direct intraoral scans. For group 1, heat-pressed glass ceramic crowns (IPS e.max Press) were fabricated using casts produced from the conventional impressions. For groups 2-4, crowns were milled using ceramic blocks (IPS e.max CAD). Ten crowns were fabricated for each group. Marginal and internal gaps were measured using a replica technique. Replicas were sectioned mesiodistally and buccolingually and were observed under a stereomicroscope. Three measurements were selected for each cut: occlusal, axial, and marginal. Statistical analysis was performed using two-way ANOVA and Tukey HSD tests.

RESULTS

For each replica, 6 measurements were made for the mesiodistal and the same for the buccolingual cuts, producing 12 measurement points per crown (4 measurements for marginal, 4 for axial, 4 for occlusal), 120 measurements for each group (40 measurements for marginal, 40 for axial, 40 for occlusal), and 480 measurements in total. Two-way ANOVA revealed location to be a significant factor (p = 0.001). No significant differences among groups (p = 0.456), and no interactions between groups and locations (p = 0.221) were found. Means for the occlusal site were significantly larger than other sites in most group combinations, while the difference between the marginal and axial sites was not significant. No significant differences among groups were found for each measurement. The marginal gaps ranged from 125.46 ± 25.39 μm for group 3 to 135.59 ± 24.07 μm for group 4. The smallest axial mean was in group 1 (98.10 ± 18.77 μm), and the largest was 127.25 ± 19.79 μm in group 4. The smallest occlusal mean was in group 2 (166.53 ± 36.51 μm), and the largest occlusal mean was in group 3 (203.32 ± 80.24 μm).

CONCLUSIONS

Ceramic crowns, which were made using all-digital approach or cast digitization by a laboratory or intraoral scanner had comparable fit to those produced by conventional approach.

Evaluation of replicas manufactured in a 3D-printed nanoimprint unit

Nanoimprint lithography has become a useful tool to prepare elements containing nanoscale features at quite reasonable cost, especially if the fabrication elements are created in the own laboratory. We have designed and fabricated a whole nanoimprint manufacturing system and analyzed the resulting surfaces using ad hoc packages developed on an open-software AFM image analysis suite. To complete the work, a number of polymers have been thoroughly studied in order to select the best material for this implementation. It turned out that the best alternative was not always the same, but depended on the application. A comparative study of the polymers, which takes into account the values and dispersion of numerous sample parameters, has been carried out. As a large number of samples was prepared, an automatized procedure for characterization of nanoimprint surfaces had to be set up. The procedure includes figures of merit for comparative purposes. Materials without the requirement of a solvent were found to be superior for most nanoimprint applications. A large dispersion of the samples was found.

Replication Strategy for Spatiotemporal Data Based on Distributed Caching System

The replica strategy in distributed cache can effectively reduce user access delay and improve system performance. However, developing a replica strategy suitable for varied application scenarios is still quite challenging, owing to differences in user access behavior and preferences. In this paper, a replication strategy for spatiotemporal data (RSSD) based on a distributed caching system is proposed. By taking advantage of the spatiotemporal locality and correlation of user access, RSSD mines high popularity and associated files from historical user access information, and then generates replicas and selects appropriate cache node for placement. Experimental results show that the RSSD algorithm is simple and efficient, and succeeds in significantly reducing user access delay.

Shadow analysis via the C+K Visioline: A technical note

BACKGROUND/PURPOSE

This research investigated the ability of shadow analysis (via the Courage + Khazaka Visioline and Image Pro Premiere 9.0 software) to accurately assess the differences in skin topography associated with photo aging.

METHODS

Analyses were performed on impressions collected from a microfinish comparator scale (GAR Electroforming) as well a series of impressions collected from the crow's feet region of 9 women who represent each point on the Zerweck Crow's Feet classification scale. Analyses were performed using a Courage + Khazaka Visioline VL 650 as well as Image Pro Premiere 9.0 software.

RESULTS

Shadow analysis showed an ability to accurately measure the groove depth when measuring impressions collected from grooves of known depth. Several shadow analysis parameters showed a correlation with the expert grader ratings of crow's feet when averaging measurements taken from the North and South directions. The Max Depth parameter in particular showed a strong correlation with the expert grader's ratings which improved when a more sophisticated analysis was performed using Image Pro Premiere.

CONCLUSION

When used properly, shadow analysis is effective at accurately measuring skin surface impressions for differences in skin topography. Shadow analysis is shown to accurately assess the differences across a range of crow's feet severity correlating to a 0-8 grader scale. The Visioline VL 650 is a good tool for this measurement, with room for improvement in analysis which can be achieved through third party image analysis software.

Full-Arch, Implant-Supported Monolithic Zirconia Rehabilitations: Pilot Clinical Evaluation of Wear Against Natural or Composite Teeth

PURPOSE

To clinically evaluate the amount of contact wear generated between full-arch monolithic zirconia implant-supported restorations and natural or composite antagonists, over a 1-year period.

MATERIALS AND METHODS

Forty-seven teeth from clinically functional, full-arch monolithic zirconia screw-retained implant prostheses (FDPs) and their antagonists were investigated. The first group ("Zirconia-E") was opposed to natural teeth ("Enamel"), whereas the other one ("Zirconia-CR") was opposed to nano-hybrid composite teeth ("Composite Resin"). Replicas of the restorations and their antagonists were obtained immediately after delivery (T₀ ) and after 1 year of clinical service (T₁ ). Each tooth surface was individually evaluated three-dimensionally by software to quantify the vertical distance between the two scans (Hausdorff distance), which was considered as contact wear. Data obtained for each arch were subjected to one-way ANOVA test and a post hoc analysis (Tukey's test) at a 5% level of significance. Furthermore, the influence of the location of the teeth (anterior or posterior) was analyzed. Minimum post hoc statistical power between statistically different groups was 99.6%.

RESULTS

Mean values were 63 ± 23 μm for Zirconia-E, 76 ± 29 μm for enamel, 70 ± 38 μm for composite resin; Zirconia-CR had a mean value of 19 ± 4 μm and significantly differed from the other groups. Contact wear between anterior and posterior teeth differed significantly only in the composite resin arch, with a mean of 39 ± 22 μm for anterior teeth versus 101 ± 19 μm for posterior ones.

CONCLUSIONS

Within the limitations of this preliminary evaluation, monolithic zirconia full-arch rehabilitations induced a clinically acceptable wear on natural and composite antagonists over a 1-year period; they might be considered a viable solution for implant-supported rehabilitations.

Rapid Prototyping of Nanofluidic Slits in a Silicone Bilayer

This article reports a process for rapidly prototyping nanofluidic devices, particularly those comprising slits with microscale widths and nanoscale depths, in silicone. This process consists of designing a nanofluidic device, fabricating a photomask, fabricating a device mold in epoxy photoresist, molding a device in silicone, cutting and punching a molded silicone device, bonding a silicone device to a glass substrate, and filling the device with aqueous solution. By using a bilayer of hard and soft silicone, we have formed and filled nanofluidic slits with depths of less than 400 nm and aspect ratios of width to depth exceeding 250 without collapse of the slits. An important attribute of this article is that the description of this rapid prototyping process is very comprehensive, presenting context and details which are highly relevant to the rational implementation and reliable repetition of the process. Moreover, this process makes use of equipment commonly found in nanofabrication facilities and research laboratories, facilitating the broad adaptation and application of the process. Therefore, while this article specifically informs users of the Center for Nanoscale Science and Technology (CNST) at the National Institute of Standards and Technology (NIST), we anticipate that this information will be generally useful for the nanofabrication and nanofluidics research communities at large, and particularly useful for neophyte nanofabricators and nanofluidicists.

A quantitative evaluation method of skin texture affected by skin ageing using replica images of the cheek

OBJECTIVE

Skin texture is a fine structure of skin surface where the hill and furrow were crossed to form a star shape. This study was performed to establish a quantitative evaluation method of skin texture affected by skin ageing using replica images of the cheek.

METHODS

After producing replicas of the left cheek areas of 80 female subjects, representative replica images were chosen to establish six-level facial skin texture index. Using this new index, skin texture of different-aged subjects was visually assessed by multiple examiners. The number of star configurations was also analysed using the same replica images. Other factors contributing to skin texture, such as skin elasticity, roughness, dermal density, moisture and gloss, were also analysed.

RESULTS

The concordance between skin texture scores evaluated by three researchers was high (0.896), and there was a high correlation between skin texture score and age (r = 0.642). The number of star configurations showed high correlations with skin texture scores (r = 0.753) and with age (r = 0.776). Skin texture scores were highly correlated with skin roughness and dermal density, but not with moisture, gloss and elasticity.

CONCLUSION

This study suggests that visual grading of skin texture score based on new facial skin texture index and quantification of star configurations will be useful in evaluating skin ageing.

Neurite outgrowth at the biomimetic interface

Understanding the cues that guide axons and how we can optimize these cues to achieve directed neuronal growth is imperative for neural tissue engineering. Cells in the local environment influence neurons with a rich combination of cues. This study deconstructs the complex mixture of guidance cues by working at the biomimetic interface--isolating the topographical information presented by cells and determining its capacity to guide neurons. We generated replica materials presenting topographies of oriented astrocytes (ACs), endothelial cells (ECs), and Schwann cells (SCs) as well as computer-aided design materials inspired by the contours of these cells (bioinspired-CAD). These materials presented distinct topographies and anisotropies and in all cases were sufficient to guide neurons. Dorsal root ganglia (DRG) cells and neurites demonstrated the most directed response on bioinspired-CAD materials which presented anisotropic features with 90 degrees edges. DRG alignment was strongest on SC bioinspired-CAD materials followed by AC bioinspired-CAD materials, with more uniform orientation to EC bioinspired-CAD materials. Alignment on replicas was strongest on SC replica materials followed by AC and EC replicas. These results suggest that the topographies of anisotropic tissue structures are sufficient for neuronal guidance. This work is discussed in the context of feature dimensions, morphology, and guidepost hypotheses.