Forces and trauma associated with minimally invasive image-guided cochlear implantation

Objective. Minimally invasive image-guided cochlear implantation (CI) utilizes a patient-customized microstereotactic frame to access the cochlea via a single drill-pass. We investigate the average force and trauma associated with the insertion of lateral wall CI electrodes using this technique. Study Design. Assessment using cadaveric temporal bones. Setting. Laboratory setup. Subjects and Methods. Microstereotactic frames for 6 fresh cadaveric temporal bones were built using CT scans to determine an optimal drill path following which drilling was performed. CI electrodes were inserted using surgical forceps to manually advance the CI electrode array, via the drilled tunnel, into the cochlea. Forces were recorded using a 6-axis load sensor placed under the temporal bone during the insertion of lateral wall electrode arrays (2 each of Nucleus CI422, MED-EL standard, and modified MED-EL electrodes with stiffeners). Tissue histology was performed by microdissection of the otic capsule and apical photo documentation of electrode position and intracochlear tissue. Results. After drilling, CT scanning demonstrated successful access to cochlea in all 6 bones. Average insertion forces ranged from 0.009 to 0.078 N. Peak forces were in the range of 0.056 to 0.469 N. Tissue histology showed complete scala tympani insertion in 5 specimens and scala vestibuli insertion in the remaining specimen with depth of insertion ranging from 360° to 600°. No intracochlear trauma was identified. Conclusion. The use of lateral wall electrodes with the minimally invasive image-guided CI approach was associated with insertion forces comparable to traditional CI surgery. Deep insertions were obtained without identifiable trauma. © American Academy of Otolaryngology-Head and Neck Surgery Foundation 2014

Select pyrimidinones inhibit the propagation of the malarial parasite, Plasmodium falciparum

Plasmodium falciparum, the Apicomplexan parasite that is responsible for the most lethal forms of human malaria, is exposed to radically different environments and stress factors during its complex lifecycle. In any organism, Hsp70 chaperones are typically associated with tolerance to stress. We therefore reasoned that inhibition of P. falciparum Hsp70 chaperones would adversely affect parasite homeostasis. To test this hypothesis, we measured whether pyrimidinone-amides, a new class of Hsp70 modulators, could inhibit the replication of the pathogenic P. falciparum stages in human red blood cells. Nine compounds with IC50 values from 30 nM to 1.6 μM were identified. Each compound also altered the ATPase activity of purified P. falciparum Hsp70 in single-turnover assays, although higher concentrations of agents were required than was necessary to inhibit P. falciparum replication. Varying effects of these compounds on Hsp70s from other organisms were also observed. Together, our data indicate that pyrimidinone-amides constitute a novel class of anti-malarial agents. © 2009 Elsevier Ltd. All rights reserved

Effective User Interface design for Teachable

This paper discusses the improvements to the user interface of a system designed to promote learning through teaching. The system is an intelligent agent developed at Vanderbilt University for studying the learning by teaching paradigm and is called Betty’s Brain. In the Betty’s Brain system, students teach a computer agent, named Betty, by creating a concept map using a visual interface. Students themselves learn through the process of instructing the agent. Fifth grade students in Nashville public schools are participating in studies on this system. In this work, we analyze the interface components of Betty’s Brain that enable the user to organize and input problem solving knowledge about a domain for the purpose of instructing the intelligent agent. The existing interface was also streamlined. We then conducted a comparative user study to evaluate our changes to the interface. Both qualitative and quantitative improvements in the user’s performance are reported. These results should provide useful guidance for designers of the next generation of learning by teaching systems

Interface Design Issues for Teachable Agent Systems

Abstract: This paper discusses improvements to the user interface of a system designed to promote learning through teaching. This system, called Betty’s Brain, is an intelligent agent developed at Vanderbilt University for studying the learning by teaching paradigm. In the Betty’s Brain system, students teach a computer agent by creating a concept map using a visual interface. Student

Numerical Investigation of an Axis-based Approach to Rigid Registration

The term rigid registration identifies the process that optimally aligns different data sets whose information has to be merged, as in the case of robot calibration, image-guided surgery or patient-specific gait analysis. One of the most common approaches to rigid registration relies on the identifica-tion of a set of fiducial points in each data set to be registered to compute the rototranslational matrix that optimally aligns them. Both measurement and hu-man errors directly affect the final accuracy of the process. Increasing the number of fiducials may improve registration accuracy but it will also increase the time and complexity of the whole procedure, since correspondence must be estab-lished between fiducials in different data sets. The aim of this paper is to present a new approach that resorts to axes instead of points as fiducial features. The fundamental advantage is that any axis can be easily identified in each data set by least-square linear fitting of multiple, un-sorted measured data. This provides a way to filtering the measurement error within each data set, improving the registration accuracy with a reduced effort. In this work, a closed-form solution for the optimal axis-based rigid registration is presented. The accuracy of the method is compared with standard point-based rigid registration through a numerical test. Axis-based registration results one or-der of magnitude more accurate than point-based registration