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You searched for subject:( electrode selection). Showing records 1 – 2 of 2 total matches.

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Duke University

1. Duran, Sara Ingrid. Psychophysics-Based Electrode Selection for Cochlear Implant Listeners .

Degree: 2014, Duke University

Cochlear implant listeners are presented with a time and frequency-quantized version of speech signals. In the frequency domain, resolution is limited by the number of electrodes in each listener's array. Current cochlear implant speech processing strategies implicitly assume that the information presented to each one of these electrodes is perceived as unique and independent. However, previous research suggests that stimuli presented on different electrodes can be indiscriminable (e.g. Zwolan et al., 1997; Throckmorton and Collins, 1999; Henry et al., 2000) . Additional studies suggest that stimuli presented on one electrode can influence the perception of stimuli on neighboring electrodes (e.g. Shannon, 1990; Chatterjee and Shannon, 1998; Boëx et al., 2003). Removing this redundant or occluded information could cause more distinct or perceivable information to be presented to the listener and possibly result in improved speech recognition. Previous studies have used psychophysical data to identify the electrodes with the highest potential to confound speech recognition (Zwolan et al., 1997, Boëx et al., 2003, and Garadat et al., 2012). In order to minimize electrode interactions and maximize the amount of perceivable information, each of these studies used a single psychophysical metric to deactivate the electrodes across all time windows of the speech processing strategy. For some listeners, these reduced electrode sets resulted in improved speech recognition over using the of the electrodes in their array. These studies did not compare the results of using different psychophysical metrics to exclude electrodes for a group of listeners nor did they investigate speech recognition performance as a function of the number of electrodes excluded from the array. In this work, three different psychophysical metrics were used to obtain a multidimensional estimate of the potential "usefulness'' of each electrode. These results were then used to inform two different methods of psychophysics-motivated electrode selection. The first method incorporated individual data into each listener's energy-driven speech processing strategy. For each time window, the electrodes with the highest energy that were also most likely to be perceived, according to the psychophysical data, were selected for stimulation. The second method sequentially excluded the electrodes with the highest potential to confound from the array across all time windows, resulting in a group of psychophysics-motivated electrode sets for each metric. Evaluating each of these electrode sets exhaustively would require a prohibitive amount of experimental time. To mitigate this problem, an adaptive procedure was developed to estimate performance as a function of cochlear implant parameters in a time-efficient manner. For each metric, the procedure estimated the set with the highest estimated probability of correct phoneme identification. Listeners' speech recognition performance using this electrode set was then compared to their performance using their… Advisors/Committee Members: Collins, Leslie M (advisor).

Subjects/Keywords: Electrical engineering; cochlear implants; electrode selection; psychophysics; speech processing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Duran, S. I. (2014). Psychophysics-Based Electrode Selection for Cochlear Implant Listeners . (Thesis). Duke University. Retrieved from http://hdl.handle.net/10161/8700

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Duran, Sara Ingrid. “Psychophysics-Based Electrode Selection for Cochlear Implant Listeners .” 2014. Thesis, Duke University. Accessed October 17, 2019. http://hdl.handle.net/10161/8700.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Duran, Sara Ingrid. “Psychophysics-Based Electrode Selection for Cochlear Implant Listeners .” 2014. Web. 17 Oct 2019.

Vancouver:

Duran SI. Psychophysics-Based Electrode Selection for Cochlear Implant Listeners . [Internet] [Thesis]. Duke University; 2014. [cited 2019 Oct 17]. Available from: http://hdl.handle.net/10161/8700.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Duran SI. Psychophysics-Based Electrode Selection for Cochlear Implant Listeners . [Thesis]. Duke University; 2014. Available from: http://hdl.handle.net/10161/8700

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Iowa State University

2. Li, Min. Dielectrophoresis at wireless bipolar electrode arrays: Applications to the marker-free selection and detection of circulating tumor cells.

Degree: 2018, Iowa State University

Metastasis is responsible for approximately 90% of cancer related deaths. The key step in metastasis is the migration of cancer cells out of the primary tumor and into bloodstream. Once reaching at a distant site, a fraction of these circulating tumor cells (CTCs) invades foreign tissues for subsequent growth of tumors. However, conventional cancer treatments ignore the metastatic process, resulting in cancer relapse. Consequently, the isolation and characterization of CTCs are crucial in understanding how cancer spread by metastasis. The enormous value of CTCs has not been completely realized because isolation of CTCs – the first inevitable step of overall analysis, is incredibly challenging due to their extreme rarity and varied physical and biological characteristics. Thus, separation techniques that exhibit the following features are critical: (i) They must provide a pure and representative sample of CTCs; (ii) Separation of individual CTCs are mandatory considering subpopulations can be easily obscured at the bulk scale; (iii) The sorting process is continuous and high-throughput since detection of a rare phenotype or cellular response requires analysis of thousands of individual cells; (iv) Captured single-cells should be readily interfaced with assays for downstream analysis. (v) Devices need to be cost-effective, accessible, and simple in manufacturing and operation for a wide range of applications. Microfluidic lab-on-a-chip (LOC) technologies possess micron-scale dimensions and picoliter-to- nanoliter volume handling capacities, thereby facilitating manipulation and sampling of single cells. However, they often suffer from lack of selectivity, being over- or under-selective. Selection must happen prior to the isolation step for analysis of individual cells. Further, many LOC devices have difficulty in interfacing with assays, or complexity that hinders their applications. Thus, the development of fully integrated devices that offer simplicity in manufacturing and operation remains an important challenge. Separation based on dielectrophoresis (DEP) exhibits less bias when compared with size- and antibody-based approaches, as it leverages the electrophysiological properties of CTCs. However, many of the current approaches to DEP suffer from low throughput and are not amenable to on-chip single-cell analysis. These limitations stem from design constraints such as the requirement that all electrodes must be connected via wire leads to the power source. Further, in DEP devices that employ insulating posts to shape the electric field, integration of these structures intended for cell capture with other features, such as chambers for on-chip analysis, is non-trivial. The work presented in this document centers on the development of DEP devices at wireless bipolar electrode (BPE) arrays to addresses these concerns. First, DEP is employed to selectively capture and isolate CTCs in micropockets, while blood cells flow through the channels. The capture methodology used here eliminates massively screening of all cell…

Subjects/Keywords: Bipolar electrode; Circulating tumor cells; Dielectrophoresis; Marker-free selection; Microfluidic lab-on-a-chip technology; Single-cell analysis; Analytical Chemistry; Biochemistry

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Li, M. (2018). Dielectrophoresis at wireless bipolar electrode arrays: Applications to the marker-free selection and detection of circulating tumor cells. (Thesis). Iowa State University. Retrieved from https://lib.dr.iastate.edu/etd/16841

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Li, Min. “Dielectrophoresis at wireless bipolar electrode arrays: Applications to the marker-free selection and detection of circulating tumor cells.” 2018. Thesis, Iowa State University. Accessed October 17, 2019. https://lib.dr.iastate.edu/etd/16841.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Li, Min. “Dielectrophoresis at wireless bipolar electrode arrays: Applications to the marker-free selection and detection of circulating tumor cells.” 2018. Web. 17 Oct 2019.

Vancouver:

Li M. Dielectrophoresis at wireless bipolar electrode arrays: Applications to the marker-free selection and detection of circulating tumor cells. [Internet] [Thesis]. Iowa State University; 2018. [cited 2019 Oct 17]. Available from: https://lib.dr.iastate.edu/etd/16841.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Li M. Dielectrophoresis at wireless bipolar electrode arrays: Applications to the marker-free selection and detection of circulating tumor cells. [Thesis]. Iowa State University; 2018. Available from: https://lib.dr.iastate.edu/etd/16841

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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