Linda Powers | University of Arizona (original) (raw)
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Papers by Linda Powers
Biochimica Et Biophysica Acta-protein Structure and Molecular Enzymology, 2001
The catalase-peroxidase encoded by katG of Mycobacterium tuberculosis is a more effective activat... more The catalase-peroxidase encoded by katG of Mycobacterium tuberculosis is a more effective activator of the antibiotic isoniazid than is the equivalent enzyme from Escherichia coli. The environment of the heme iron was investigated using X-ray absorption spectroscopy to determine if differences in this region were associated with the differences in reactivity. The variation in the distal side Fe^ligand distances between the two enzymes was the same within experimental error indicating that it was not the heme iron environment that produced the differences in reactivity. Analysis of variants of the E. coli catalase-peroxidase containing changes in active site residues Arg102 and His106 revealed small differences in Fe^water ligand distance including a shorter distance for the His106Tyr variant. The Arg102Leu variant was 5-coordinate, but His106Cys and Arg102Cys variants showed no changes within experimental error. These results are compared with those reported for other peroxidases. ß 2001 Elsevier Science B.V. All rights reserved.
Biosensors and Bioelectronics, 2003
Quick and accurate detection of microbial contamination is accomplished by a unique combination o... more Quick and accurate detection of microbial contamination is accomplished by a unique combination of leading-edge technologies described in this and the accompanying paper. In this contribution, a hand-held prototype instrument is described which is capable of statistically sampling the environment for microbial contamination and determining cell viability. The technology is sensitive enough to detect very low levels ( Â/20 cells/cm 2 or cm 3 ) of microbes in seconds. #
2014 27th IEEE International System-on-Chip Conference (SOCC), 2014
2014 International Conference on Information Science, Electronics and Electrical Engineering, 2014
IERI Procedia, 2013
ABSTRACT Modern multi-core design will continue Moore's law and facilitate platforms for ... more ABSTRACT Modern multi-core design will continue Moore's law and facilitate platforms for both wired and wireless communications. It is also predicted that multi-core, as a popular computing platform, will need to have the capability to process “big data” with both high speed and high quality. However, slow dynamic interactions and data exchange are the two key challenges in the multi-core design. This paper discusses two new strategies that can potentially solve these two issues. First, we discuss a new “Communication-time Cost Minimization” (CCM) approach to reduce the communications between different cores. Then we discuss how to manage tasks and their associated data to achieve “Request Cancellation”to common structures such as memory or stack.We have demonstrated an average reduction of 50% in the communication- time cost, an average of 23.1% of throughput improvement, and a linear increase of request executions for the shared memory stack.
Most electronic systems in biology and medical applications are used to control spectroscopic/ima... more Most electronic systems in biology and medical applications are used to control spectroscopic/imaging instrumentation for the identification of certain features in the input samples and/or to save and manipulate this data for analysis by medical personnel. This paper identifies the effective signal regions (ESR) for analog mixed signal designs through applications. These ESRs are mapped onto a performance response surface for analog mixed signal circuits. For op-amps and ADCs, the models for nonlinearity and transfer functions will also focus on the ESRs instead of the whole frequency spectrum. Consequently, analog mixed signal designs can take advantage of this to improve the interrogated region and power consumption.
Biochimica Et Biophysica Acta-protein Structure and Molecular Enzymology, 2001
The catalase-peroxidase encoded by katG of Mycobacterium tuberculosis is a more effective activat... more The catalase-peroxidase encoded by katG of Mycobacterium tuberculosis is a more effective activator of the antibiotic isoniazid than is the equivalent enzyme from Escherichia coli. The environment of the heme iron was investigated using X-ray absorption spectroscopy to determine if differences in this region were associated with the differences in reactivity. The variation in the distal side Fe^ligand distances between the two enzymes was the same within experimental error indicating that it was not the heme iron environment that produced the differences in reactivity. Analysis of variants of the E. coli catalase-peroxidase containing changes in active site residues Arg102 and His106 revealed small differences in Fe^water ligand distance including a shorter distance for the His106Tyr variant. The Arg102Leu variant was 5-coordinate, but His106Cys and Arg102Cys variants showed no changes within experimental error. These results are compared with those reported for other peroxidases. ß 2001 Elsevier Science B.V. All rights reserved.
Biosensors and Bioelectronics, 2003
Quick and accurate detection of microbial contamination is accomplished by a unique combination o... more Quick and accurate detection of microbial contamination is accomplished by a unique combination of leading-edge technologies described in this and the accompanying paper. In this contribution, a hand-held prototype instrument is described which is capable of statistically sampling the environment for microbial contamination and determining cell viability. The technology is sensitive enough to detect very low levels ( Â/20 cells/cm 2 or cm 3 ) of microbes in seconds. #
2014 27th IEEE International System-on-Chip Conference (SOCC), 2014
2014 International Conference on Information Science, Electronics and Electrical Engineering, 2014
IERI Procedia, 2013
ABSTRACT Modern multi-core design will continue Moore's law and facilitate platforms for ... more ABSTRACT Modern multi-core design will continue Moore's law and facilitate platforms for both wired and wireless communications. It is also predicted that multi-core, as a popular computing platform, will need to have the capability to process “big data” with both high speed and high quality. However, slow dynamic interactions and data exchange are the two key challenges in the multi-core design. This paper discusses two new strategies that can potentially solve these two issues. First, we discuss a new “Communication-time Cost Minimization” (CCM) approach to reduce the communications between different cores. Then we discuss how to manage tasks and their associated data to achieve “Request Cancellation”to common structures such as memory or stack.We have demonstrated an average reduction of 50% in the communication- time cost, an average of 23.1% of throughput improvement, and a linear increase of request executions for the shared memory stack.
Most electronic systems in biology and medical applications are used to control spectroscopic/ima... more Most electronic systems in biology and medical applications are used to control spectroscopic/imaging instrumentation for the identification of certain features in the input samples and/or to save and manipulate this data for analysis by medical personnel. This paper identifies the effective signal regions (ESR) for analog mixed signal designs through applications. These ESRs are mapped onto a performance response surface for analog mixed signal circuits. For op-amps and ADCs, the models for nonlinearity and transfer functions will also focus on the ESRs instead of the whole frequency spectrum. Consequently, analog mixed signal designs can take advantage of this to improve the interrogated region and power consumption.