MARSBot: A Bristle-Bot Microrobot with Augmented Reality Steering Control for Wireless Structural Health Monitoring.

Microrobots are effective for monitoring infrastructure in narrow spaces. However, they have limited computing power, and most of them are not wireless and stable enough for accessing infrastructure in difficult-to-reach areas. In this paper, we describe the fabrication of a microrobot with bristle-bot locomotion using a novel centrifugal yaw-steering control scheme. The microrobot operates in a network consisting of an augmented reality headset and an access point to monitor infrastructures using augmented reality (AR) haptic controllers for human-robot collaboration. For the development of the microrobot, the dynamics of bristle-bots in several conditions were studied, and multiple additive manufacturing processes were investigated to develop the most suitable prototype for structural health monitoring. Using the proposed network, visual data are sent in real time to a hub connected to an AR headset upon request, which can be utilized by the operator to monitor and make decisions in the field. This allows the operators wearing an AR headset to inspect the exterior of a structure with their eyes, while controlling the surveying robot to monitor the interior side of the structure.

Interfacial Mechanical Behavior in Nacre of Red Abalone and Other Shells: A Review.

Interfaces between nacreous tablets are crucial to the outstanding mechanical properties of nacre in natural shells. Excellent research has been conducted to probe the effect of interfaces on strength and toughness of nacre, providing critical guidelines for the design of human-made laminated composites. This article reviews recent studies on interfacial mechanical behavior of nacre in red abalone and other shells, including experimental methods, analytical and numerical modeling. The discussions focus on the mechanical properties of dry and hydrated nacreous microstructures. The review concludes with discussions on representative studies of nacre-like composites with interfaces tuned using multiple approaches, and provides an outlook on improving the performance of composites with better interfacial controls.

Simulating hydraulic interdependence between bridges along a river corridor under transient flood conditions.

Structural alterations to bridges may result in unintended consequences up- or downstream, such as changes in discharge, velocity, stream power, and water levels. This work presents a framework and methodology to analyze interconnected bridge-stream interactions under flood conditions. Such analysis may help prioritize limited resources available for bridge and river rehabilitations, facilitate holistic design of bridges and better-informed cost/benefit analyses, and address stakeholder concerns raised in response to planned bridge and infrastructure alterations. A two-dimensional unsteady HEC-RAS hydraulic model of the Otter Creek between Rutland and Middlebury, VT is used to simulate the impact of individual structures on the bridge-stream network, as well as potential sensitivity to those impacts, during extreme flood events. The presence of a bridge and approach roadway may induce measurable changes in peak discharge throughout the entire 46 miles of modeled river. These may be by as much as 10% at adjacent structures, down to 1% at structures as far as six miles upstream and nine miles downstream. Depending on their characteristics, bridges and roadways may either attenuate or amplify peak flood flows up- and downstream, or have little to no effect at all, suggesting that there is no easily predictable impact, and that hydraulic modeling is necessary for such analysis on rivers. Alterations to structures that develop substantial backwaters may result in the most dramatic impacts to the network, which can be both positive and negative. Affected bridges may or may not be sensitive to these changes in discharge; structures that do not experience relief (e.g., roadway overtopping) may be most sensitive to any distant perturbations.

Avian lungs: A novel scaffold for lung bioengineering.

Allogeneic lung transplant is limited both by the shortage of available donor lungs and by the lack of suitable long-term lung assist devices to bridge patients to lung transplantation. Avian lungs have different structure and mechanics resulting in more efficient gas exchange than mammalian lungs. Decellularized avian lungs, recellularized with human lung cells, could therefore provide a powerful novel gas exchange unit for potential use in pulmonary therapeutics. To initially assess this in both small and large avian lung models, chicken (Gallus gallus domesticus) and emu (Dromaius novaehollandiae) lungs were decellularized using modifications of a detergent-based protocol, previously utilized with mammalian lungs. Light and electron microscopy, vascular and airway resistance, quantitation and gel analyses of residual DNA, and immunohistochemical and mass spectrometric analyses of remaining extracellular matrix (ECM) proteins demonstrated maintenance of lung structure, minimal residual DNA, and retention of major ECM proteins in the decellularized scaffolds. Seeding with human bronchial epithelial cells, human pulmonary vascular endothelial cells, human mesenchymal stromal cells, and human lung fibroblasts demonstrated initial cell attachment on decellularized avian lungs and growth over a 7-day period. These initial studies demonstrate that decellularized avian lungs may be a feasible approach for generating functional lung tissue for clinical therapeutics.

Catastrophic failure of nacre under pure shear stresses of torsion.

Nacre, a composite made from biogenic aragonite and proteins, exhibits excellent strength and toughness. Here, we show that nacreous sections can exhibit complete brittle fracture along the tablet interfaces at the proportional limit under pure shear stresses of torsion. We quantitatively separate the initial tablet sliding primarily resisted by nanoscale aragonite pillars from the following sliding resisted by various microscale toughening mechanisms. We postulate that the ductility of nacre can be limited by eliminating tablet interactions during crack propagations. Our findings should help pursuing further insights of layered materials by using torsion.

Texture analysis of post breast cancer lymphedema ultrasound images obtained using a portable device--a pilot study.

BACKGROUND: Lymphedema is a common complaint of post-breast cancer treatment. Some prior ultrasound imaging studies of lymphedema-affected upper extremities focused upon estimating the thickness of the dermis and subcutis areas. In contrast, however, the reliability and validity of texture features derived from ultrasound images obtained using a low-cost portable ultrasound device have not been reported. This study examined the reliability and validity of the first and second order quantitative image texture measures, average pixel intensity and entropy, and compared their site-specific correlations. METHODS AND RESULTS: A total of 10 ultrasound images of an ipsilateral affected elbow and the corresponding unaffected contralateral elbow were obtained using a portable ultrasound device. A Graphical User Interface software package for image analysis was developed and tested. Entropy and average pixel intensity at six adjacent regions of interest corresponding to the dermis and subcutis areas were calculated. Entropy had smaller coefficients of variation for each image compared to average pixel intensity with the intracluster correlation reliability coefficient for entropy being twice that of average pixel intensity. Both measures discriminated between the affected and unaffected sites (p < 0.001). However, the correlation between the two measures differed for affected (r = -0.060, p = 0.667) and unaffected (r = +0.595, p < 0.001) sites. CONCLUSIONS: The second order measure entropy is preferable to that of the first order average pixel intensity as a measure of image texture to characterize ultrasound images of extremity lymphedema.

Halovest dynamic loads: full crossover comparison of three vest types.

STUDY DESIGN: Ten cervical spine trauma subjects were studied during halovest treatment. Each subject wore each of three different vests. OBJECTIVES: To compare the effect of vest design on loads between halo and vest during various activities. SUMMARY OF BACKGROUND DATA: Complications during halovest use may be related to vest design, a variety of which are available. Loads between halo and vest have been shown to vary with activity type, but no comparison between vest types has been reported previously. METHODS: Loads between the halo and the vest were measured during performance of activities of daily living and during load application to the halo, using custom-built four-channel transducers and a PC-based data acquisition system. RESULTS: Substantial variations between subjects exist in loads between the halo and the vest. At rest, neck distraction loads were significantly greater for the supine posture than for either the sitting or standing postures. Loads applied to the halo by the investigators are carried by the neck and not by the structure connecting the halo to the vest. During activities of daily living all four measured load components are generally nonzero. During activities of daily living substantial differences in loads occurred between vest types. For all activities of daily living combined, the relative neck distraction load values were as follows: 4PAD 100%, Bremer 159%, and PMT 180%. CONCLUSIONS: Previous evidence supports a connection between certain complications of halovest wear (such as pin loosening) and loads on the pins. This study shows that different halovests are associated with quite different loads between the vest and the halo (and thus loads on the pins and the neck). This is encouraging for prospective, clinical comparison of different halovests and for improvements in clinical performance through halovest design improvements.

Adapting root cause analysis to chronic medical conditions.

BACKGROUND: Root cause analysis (RCA), used to study the conditions leading to acute accidents, was adapted to analyze adverse events in chronic medical conditions. METHODS: RCA was modified to investigate "trigger events"--markers of potential adverse events--in outpatient diabetes care. For 20 cases with the trigger event of hypoglycemia evidenced by an A1C of > or = 11%, a multidisciplinary team reviewed the findings of medical record abstractions, provider interviews, and patient interviews for each case. The RCA team identified active failures, error-producing conditions, latent conditions, and defenses leading to the trigger event in each case. RESULTS: The methodology identified potential root causes of persistent hyperglycemia. Latent conditions, error-producing conditions, and active failures occurred at the assessment, planning, and implementation phases of a diabetes visit. Recurring failure modes were identified within and across cases. CONCLUSION: RCA can be used to study trigger events in medical care for chronic conditions. Although the data collection occurs months after the event, this methodology can identify variations in chronic care and stimulate discussion about potential solutions.