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Frank L Brodie,1 David A Ramirez,2,* Sundar Pandian,3,* Kelly Woo,3 Ashwin Balakrishna,3 Eugene De Juan,1 Hyuck Choo,3 Robert H Grubbs3 1Department of Ophthalmology, University of California San Francisco, San Francisco, CA, USA; 2School of Medicine, University of California San Francisco, San Francisco, CA, USA; 3Department of Medical Engineering, California Institute of Technology, Pasadena, CA, USA *These authors contributed equally to this work Introduction: Repair of retinal detachment frequently requires use of intraocular gas. Patients are instructed to position themselves postoperatively to appose the intraocular bubble to the retinal break(s). We developed a novel wearable wireless positioning sensor, which provides real-time audiovisual feedback on the accuracy of positioning.Methods: Eight healthy volunteers wore the wireless sensor for 3 hours while instructed to maintain their head tilted toward the 2 o’clock meridian with no audiovisual feedback. Positioning accuracy was recorded. The subjects repeated the experiment for 3 hours with the audiovisual feedback enabled.Results: With no audiovisual feedback, the percentage of time greater than 10° out of position varied from 8.9% to 93.9%. With audiovisual feedback enabled, these percentages ranged from 9.4% to 65%. Three subjects showed significant improvement in their time out of position (P

Frank L Brodie,1 Kelly Y Woo,2 Ashwin Balakrishna,2 Hyuck Choo,2 Robert H Grubbs2 1Department of Ophthalmology, University of California San Francisco, San Francisco, 2Department of Medical Engineering, California Institute of Technology, Pasadena, CA, USA Purpose: Surgical repair of retinal attachment or macular hole frequently requires intraocular gas. This necessitates specific postoperative positioning to improve outcomes and avoid complications. However, patients struggle with correct positioning. We have developed a novel sensor to detect the position of the gas bubble in the eye and provide feedback to patients in real time. In this paper, we determine the specificity and sensitivity of our sensor in vitro using a model eye. Methods: We assessed the reliability of our sensor to detect when a gas bubble has deviated off a model retinal break in a model eye. Various bubble sizes representing the intraocular kinetics of sulfur hexafluoride gas and varying degrees of deviation from the correct position were tested using the sensor attached to a mannequin head with a model eye. Results: We recorded 36 data points. The sensor acted appropriately in 33 (91.7%) of them. The sensor triggered the alarm every time the bubble deviated off the break (n=15, sensitivity =100%). However, it triggered the alarm (falsely) 3/21 times when the bubble was correctly positioned over the retinal break (specificity =86%). Conclusion: Our device shows excellent sensitivity (100%) and specificity (86%) in detecting whether intraocular gas is tamponading a retinal break in a model eye. Keywords: postoperative positioning, intraocular gas, vitrectomy, retinal detachment, macular hole, pneumatic retinopexy

High-carbon-content fly ashes with biomass particles are typically landfilled in accordance with the ASTM C618 regulation. To quantify their geotechnical properties relating to storage and disposal, this study evaluates the small to intermediate strain properties of fly ashes with various carbon and biomass contents. Tested fly ashes had carbon contents ranging from 1.1% to 9.6%, resulting from co-combusting coal with biomass (biomass contents ranging from 0% to 8.2% by weight). The small-strain stiffness and intermediate-strain constrained modulus were evaluated using consolidation tests performed in a modified oedometer cell equipped with bender elements. It was found that initial void ratio governed the compressibility (or constrained modulus) of fly ashes, and with an increase in carbon and biomass contents, the small-strain stiffness of fly ashes decreased due to the decrease in number of direct contacts between microspheres. In addition, the interfine void ratio, ef, was employed instead of global void ratio to capture the alteration of interparticle contact or interparticle coordination between microspheres, due to the change in carbon and biomass contents. Finally, the stiffness in an overconsolidated state and the stiffness anisotropy of fly ashes were evaluated. Key words: fly ash, unburned carbon particle, biomass particle, maximum shear modulus, constrained modulus. Les cendres volantes a forte teneur en carbone et contenant des particules de biomasse sont habituellement mises en decharge conformement a la norme ASTM C618. Afin de quantifier les parametres geotechniques de stockage et d'elimination de ces cendres, la presente etude evalue les proprietes, en presence de contraintes faibles a moderees, de cendres volantes a teneur en carbone et en biomasse variable. Les cendres volantes mises a l'essai, produit de la cocombustion de charbon et de biomasse (teneur en biomasse comprise entre 0 et 8,2 % du poids total), avaient des teneurs en carbone variant entre 1,1 et 9,6 %. La rigidite en presence de faibles contraintes et le module sous contrainte pour des contraintes intermediates ont ete evalues a l'aide d'essais de consolidation realises dans une cellule redometrique modifiee et equipee de languettes piezoceramiques. On a constate que l'indice des vides initial influait sur la compressibilite (ou le module sous contrainte) des cendres volantes et que lorsque les teneurs en carbone et en biomasse augmentaient, la rigidite des cendres en presence de faibles contraintes diminuait en raison de la diminution des contacts directs entre les microspheres. En outre, on a utilise l'indice des vides entre les particules fines, ef, au lieu d'utiliser l'indice des vides global pour evaluer la modification des contacts entre particules ou de la coordination interparticulaire entre les microspheres, en raison des variations des teneurs en carbone et en biomasse. Enfin, on a evalue la rigidite a l'etat surconsolide et l'anisotropie de la rigidite des cendres volantes. [Traduit par la Redaction] Mots-cles: cendres volantes, particule de carbone imbrule, particule de biomasse, module de cisaillement maximum, module sous contrainte., Introduction The fraction of co-fired fly ash resulting from co-combusting coal with biomass has increased rapidly in recent years (Sami et al. 2001; Baxter 2005). The percentage of high carbon [...]

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