Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

Sorted by: relevance · author · university · dateNew search

You searched for subject:(pulse repetition frequency). Showing records 1 – 2 of 2 total matches.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


North Carolina State University

1. Marvel, Skylar. The Importance of Low Intensity Pulsed Ultrasound Parameters for Functional Bone Tissue Engineering using Adult Stem Cells.

Degree: MS, Biomedical Engineering, 2009, North Carolina State University

Functional bone tissue engineering is a very important emerging interdisciplinary field of research. The treatments of bone loss, defects, trauma and disease often require replacement bone tissue or the use of bone substitutes. Functional bone tissue engineering attempts to create this needed replacement bone tissue using a patient’s stem cells. One small aspect of this field involves being able to control the proliferation and osteogenic differentiation of a patient’s stem cells with the eventual goal of creating an autologous bone graft in vitro to correct bone defects. Two possible types of stem cells for this procedure are human bone marrow derived mesenchymal stem cells (hMSCs) and human adipose derived adult stem cells (hASCs), both of which have been shown to be capable of osteogenic differentiation. Many different stimuli are being actively researched to control this differentiation, such as fluid shear stress, tensile strain, electric fields, chemical signals and material properties of substrates to name a few. One newly investigated stimulus is low intensity pulsed ultrasound (LIPUS). Since the mid 1990s LIPUS has been used clinically to aid fracture healing and since 2000 has also been prescribed for the treatment of non-unions. Although the mechanisms have not been elucidated, LIPUS has been shown to increase expression of cellular osteogenic markers in vitro. However, the parameters of LIPUS have not been optimized for increasing osteogenic differentiation and the use of LIPUS has been untested on hASCs, both of which could potentially benefit the field of bone tissue engineering and are the focus of this body of work. To explore the optimization of LIPUS parameters a custom ultrasound system was designed and built to give precise control over an extensive range of values for each stimulus parameter. There were several design criteria which included making the system automatable, insuring that the system can be used with standard incubators, and reducing the amount of laboratory space required to house the system. Once built, the ultrasound system was validated by testing three different pulse repetition frequency (PRF) parameter settings for inducing osteogenic differentiation of both hMSCs and hASCs. The first set of experiments investigated effects on hASCs and showed a significant increase in calcium accretion per cell with both 1 kHz and 100 Hz PRFs; however, this result was diminished by noting that the significant differences came from variations in amounts of DNA rather than increases in calcium. The effect caused by the presence of papain digest in experimental samples on the quantification of DNA was then studied and a change in the protocol for the DNA quantification assay was made. Using the modified assay a second set of experiments investigated the effects of LIPUS on hMSCs, and although the results were not significant, there was a trend of increased calcium accretion per cell with higher PRFs indicating that, of the three PRF settings tested, the 1 kHz PRF… Advisors/Committee Members: Dr. Greg S. McCarty, Committee Member (advisor), Dr. Paul A. Dayton, Committee Co-Chair (advisor), Dr. Elizabeth G. Loboa, Committee Chair (advisor).

Subjects/Keywords: pulse repetition frequency; adipose derived adult stem cells

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Marvel, S. (2009). The Importance of Low Intensity Pulsed Ultrasound Parameters for Functional Bone Tissue Engineering using Adult Stem Cells. (Thesis). North Carolina State University. Retrieved from http://www.lib.ncsu.edu/resolver/1840.16/2793

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):

Marvel, Skylar. “The Importance of Low Intensity Pulsed Ultrasound Parameters for Functional Bone Tissue Engineering using Adult Stem Cells.” 2009. Thesis, North Carolina State University. Accessed July 15, 2020. http://www.lib.ncsu.edu/resolver/1840.16/2793.

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

MLA Handbook (7th Edition):

Marvel, Skylar. “The Importance of Low Intensity Pulsed Ultrasound Parameters for Functional Bone Tissue Engineering using Adult Stem Cells.” 2009. Web. 15 Jul 2020.

Vancouver:

Marvel S. The Importance of Low Intensity Pulsed Ultrasound Parameters for Functional Bone Tissue Engineering using Adult Stem Cells. [Internet] [Thesis]. North Carolina State University; 2009. [cited 2020 Jul 15]. Available from: http://www.lib.ncsu.edu/resolver/1840.16/2793.

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

Council of Science Editors:

Marvel S. The Importance of Low Intensity Pulsed Ultrasound Parameters for Functional Bone Tissue Engineering using Adult Stem Cells. [Thesis]. North Carolina State University; 2009. Available from: http://www.lib.ncsu.edu/resolver/1840.16/2793

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


Linköping University

2. Tornberg, Jens. MPD-vågformer för helikopterradar.

Degree: Electrical Engineering, 2003, Linköping University

A helicopter based system equipped with a millimetre-wave fire control radar is studied for improvement of the detection probability for moving ground targets. The system is a pulse doppler radar that sends out the electromagnetic wave in repetitive pulses. The frequency in which radar sends this pulse is called Pulse Repetition Frequency (PRF). The velocity of the moving targets is measured by spectral analysis of the pulses received. With this sort of system some targets will not be possible to detect. These targets are said to be blind for the radar. Also the measured targets can be ambiguous. A solution to this is to shift PRF during the time the radar emits itspulses on the target. This method is called PRF block staggering. The antenna is mounted on a mechanical sweep on top of the rotor of the helicopter. Because of this the time on target is limited. This means that the measured velocity resolution of the radar is also limited. With the studied method it is possible to resolve range and velocity ambiguities. This is under the condition that it is acceptable with a reduction in the velocity resolution by a factor equal to the number of PRF blocks used. The work leading to this thesis included developing a program in Mathworks Matlab for studying different configurations of PRFs and the effect on the detection probability.

Subjects/Keywords: Reglerteknik; radar; pulse repetition frequency; PRF; helicopter; clutter; ambiguity; Reglerteknik; Automatic control; Reglerteknik

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

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

APA (6th Edition):

Tornberg, J. (2003). MPD-vågformer för helikopterradar. (Thesis). Linköping University. Retrieved from http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1729

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):

Tornberg, Jens. “MPD-vågformer för helikopterradar.” 2003. Thesis, Linköping University. Accessed July 15, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1729.

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

MLA Handbook (7th Edition):

Tornberg, Jens. “MPD-vågformer för helikopterradar.” 2003. Web. 15 Jul 2020.

Vancouver:

Tornberg J. MPD-vågformer för helikopterradar. [Internet] [Thesis]. Linköping University; 2003. [cited 2020 Jul 15]. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1729.

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

Council of Science Editors:

Tornberg J. MPD-vågformer för helikopterradar. [Thesis]. Linköping University; 2003. Available from: http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-1729

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

.