Can Hyperspectral Imaging and Neural Network Classification Be Used for Ore Grade Discrimination at the Point of Excavation?

This work determines whether hyperspectral imaging is suitable for discriminating ore from waste at the point of excavation. A prototype scanning system was developed for this study. This system combined hyperspectral cameras and a three-dimensional LiDAR, mounted on a pan-tilt head, and a positioning system which determined the spatial location of the resultant hyperspectral data cube. This system was used to obtain scans both in the laboratory and at a gold mine in Western Australia. Samples from this mine site were assayed to determine their gold concentration and were scanned using the hyperspectral apparatus in the laboratory to create a library of labelled reference spectra. This library was used as (i) the reference set for spectral angle mapper classification and (ii) a training set for a convolutional neural network classifier. Both classification approaches were found to classify ore and waste on the scanned face with good accuracy when compared to the mine geological model. Greater resolution on the classification of ore grade quality was compromised by the quality and quantity of training data. The work provides evidence that an excavator-mounted hyperspectral system could be used to guide a human or autonomous excavator operator to selectively dig ore and minimise dilution.

Shape Dependence of Pressure-Induced Phase Transition in CdS Semiconductor Nanocrystals.

Understanding structural stability and phase transformation of nanoparticles under high pressure is of great scientific interest, as it is one of the crucial factors for design, synthesis, and application of materials. Even though high-pressure research on nanomaterials has been widely conducted, their shape-dependent phase transition behavior still remains unclear. Examples of phase transitions of CdS nanoparticles are very limited, despite the fact that it is one of the most studied wide band gap semiconductors. Here we have employed in situ synchrotron wide-angle X-ray scattering and transmission electron microscopy (TEM) to investigate the high-pressure behaviors of CdS nanoparticles as a function of particle shapes. We observed that CdS nanoparticles transform from wurtzite to rocksalt phase at elevated pressure in comparison to their bulk counterpart. Phase transitions also vary with particle shape: rod-shaped particles show a partially reversible phase transition and the onset of the structural phase transition pressure decreases with decreasing surface-to-volume ratios, while spherical particles undergo irreversible phase transition with relatively low phase transition pressure. Additionally, TEM images of spherical particles exhibited sintering-induced morphology change after high-pressure compression. Calculations of the bulk modulus reveal that spheres are more compressible than rods in the wurtzite phase. These results indicate that the shape of the particle plays an important role in determining their high-pressure properties. Our study provides important insights into understanding the phase-structure-property relationship, guiding future design and synthesis of nanoparticles for promising applications.

Negative Ulnar Variance Lessens DRUJ Instability After DRUJ Disruption: A Biomechanical Analysis.

BACKGROUND: The purpose of this study was to perform a biomechanical investigation on the effect of ulnar variance (UV) on the stability of the distal radioulnar joint (DRUJ) prior to and after DRUJ sectioning. METHODS: Ten cadaveric forearm specimens were included in the study and baseline UV was assessed radiographically. Radial motion relative to the ulna was evaluated using Intel real sense cameras and a custom developed program. The forearms were dissected, and a radial osteotomy was performed. Using a custom-made plate, radial stability was assessed with an UV of + 4, 0, and -4 mm by measuring the maximum and minimum radial position relative to the ulna during a simulated Shuck test. The volar radioulnar ligaments and triangular fibrocartilage complex (TFCC) were then sectioned, and testing was repeated at each UV state. RESULTS: Sectioning significantly increased radial translation at neutral (P = .008), +4 mm UV (P = .008), and -4 mm UV (P = .018). There were no significant differences in translation between the 3 UV groups with the DRUJ intact (P = .124). The ulnar negative (-4 mm) state had significantly lower translation compared to the positive (+4 mm) (P < .001) and the neutral (0 mm) (P = .026) UV states. There were no significant differences between the positive and neutral UV groups with the DRUJ sectioned. CONCLUSIONS: Fixating the radius in -4 mm of ulnar negativity significantly decreased radial translation after sectioning the volar radioulnar ligament and TFCC. Ulnar variance had no effect on stability with an intact DRUJ. STUDY TYPE: Biomechanical Study.

Mandibular "tripod" advancement of a Class II Division 2 deepbite malocclusion.

This case report describes the treatment of a 25-year-old woman with a Class II malocclusion, secondary to mandibular skeletal deficiency, and mild overclosure. Inferior surgical repositioning of the maxilla is often the treatment of choice for patients with maxillary vertical deficiency; however, this patient had borderline vertical deficiency that was treated with a mandibular "tripod" advancement (leveling of the mandibular arch after surgery) coupled with a setback and down-grafting genioplasty. The surgical-orthodontic treatment plan, combined with cosmetic dentistry, resulted in dramatically improved facial esthetics and occlusal relationships.

Multiparametric prostate MRI-based intensity-modulated radiation therapy guided by prostatic calcifications.

OBJECTIVES: The optimal technique to administer image-guided radiation therapy for prostate cancer remains poorly defined. This study assessed outcomes after multiparametric prostate MRI-based planning was delivered with image-guided radiation therapy using prostatic calculi observed on cone beam CT (CBCT). METHODS: Between January 2015 and December 2017, 94 consecutive patients were treated with CBCT-based image-guided radiation therapy (IGRT) without fiducial markers. MRI was routinely incorporated for target delineation and intraprostatic tumor nodules were boosted to allow reduced doses to normal appearing prostate. The primary endpoint was the prevalence of prostatic calcifications while toxicity and biochemical control were secondary endpoints. RESULTS: Median follow-up was 39.7 months with 82% NCCN intermediate to very high risk. Intraprostatic calculi were noted in 68% of patients. The 3-year biochemical control, late grade ≥2 rectal toxicity and late grade ≥2 urinary toxicity rates were 96%, 3 and 7%, respectively. Biochemical control and toxicity were not significantly impacted by the presence of prostatic calculi. CONCLUSION: Prostatic calcifications can serve as natural fiducial markers to allow for non-invasive IGRT for prostate cancer with promising early disease control and toxicity outcomes. ADVANCES IN KNOWLEDGE: Prostate calcification-guided IGRT is technically feasible.

Eavesdropping on echolocation: recording the bat's auditory experience.

Insectivorous bats are able to locate and capture insects in complete darkness while flying at high speeds. They may consume hundreds of insects each night while avoiding obstacles in a complex environment. To investigate the processes associated with bat echolocation, we have developed instrumentation that allows us to record and visualize what a bat hears while flying through its natural environment. Recordings were made using a miniaturized radio telemetry system mounted directly on the back of the bat. This paper describes the design and testing of the components of this system, presents echolocation data collected from bats and discusses issues associated with the visualization and analysis of echoes recorded in a natural setting from the bat's point-of-view. It presents a new tool for visualizing a bat's experience by generating call sequence sonograms (CSSs) based on various signal parameters. CSSs based on time series amplitude, band-limited spectral magnitude and Q-factor are presented. This work demonstrates that CSSs based on Q-factor (computed by dividing a peak frequency estimate by a bandwidth estimate) provides a relatively clear representation of the objects producing echoes encountered by a bat during a continuous flight.