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In vitro and in vivo studies of tissue engineering in reconstructive plastic surgeryHuss, Fredrik R.M. January 2005 (has links)
To correct, improve, and maintain tissues, and their functions, are common denominators in tissue engineering and reconstructive plastic surgery. This can be achieved by using autolo-gous tissues as in flaps or transplants. However, often autologous tissue is not useable. This is one of the reasons for the increasing interest among plastic surgeons for tissue engineering, and it has led to fruitful cross-fertilizations between the fields. Tissue engineering is defined as an interdisciplinary field that applies the principles of engineering and life sciences for development of biologic substitutes designed to maintain, restore, or improve tissue functions. These methods have already dramatically improved the possibilities to treat a number of medical conditions, and can arbitrarily be divided into two main principles: > Methods where autologous cells are cultured in vitro and transplanted by means of a cell suspension, a graft, or in a 3-D biodegradable matrix as carrier. > Methods where the tissue of interest is stimulated and given the right prerequisites to regenerate the tissue in vivo/situ with the assistance of implantation of specially designed materials, or application of substances that regulate cell functions - guided tissue regeneration. We have shown that human mammary epithelial cells and adipocytes could be isolated from tissue biopsies and that the cells kept their proliferative ability. When co-cultured in a 3-D matrix, patterns of ductal structures of epithelial cells embedded in clusters of adipocytes, mimicking the in vivo architecture of human breast tissue, were seen. This indicated that human autologous breast tissue can be regenerated in vitro. The adipose tissue is also generally used to correct soft tissue defects e.g. by autologous fat transplantation. Alas 30-70% of the transplanted fat is commonly resorbed. Preadipocytes are believed to be hardier and also able to replicate, and hence, are probably more useful for fat transplantation. We showed that by using cell culture techniques, significantly more pre-adipocytes could survive and proliferate in vitro compared to two clinically used techniques of fat graft handling. Theoretically, a biopsy of fat could generate enough preadipocytes to seed a biodegradable matrix that is implanted to correct a defect. The cells in the matrix will replicate at a rate that parallels the vascular development, the matrix subsequently degrades and the cell-matrix complex is replaced by regenerated, vascularized adipose tissue. We further evaluated different biodegradable scaffolds usable for tissue engineering of soft tissues. A macroporous gelatin sphere showed several appealing characteristics. A number of primary human ecto- and mesodermal cells were proven to thrive on the gelatin spheres when cultured in spinner flasks. As the spheres are biodegradable, it follows that the cells can be cultured and expanded on the same substrate that functions as a transplantation vehicle and scaffold for tissue engineering of soft tissues. To evaluate the in vivo behavior of cells and gelatin spheres, an animal study was performed where human fibroblasts and preadipocytes were cultured on the spheres and injected intra-dermally. Cell-seeded spheres were compared with injections of empty spheres and cell suspensions. The pre-seeded spheres showed a near complete regeneration of the soft tissues with neoangiogenesis. Some tissue regeneration was seen also in the ‘naked’ spheres but no effect was shown by cell injections. In a human pilot-study, intradermally injected spheres were compared with hyaluronan. Volume-stability was inferior to hyaluronan but a near complete regeneration of the dermis was proven, indicating that the volume-effect is permanent in contrast to hyaluronan which eventually will be resorbed. Further studies are needed to fully evaluate the effect of the macroporous gelatin spheres, with or without cellular pre-seeding, as a matrix for guided tissue regeneration. However, we believe that the prospect to use these spheres as an injectable, 3D, biodegradable matrix will greatly enhance our possibilities to regenerate tissues through guided tissue regeneration. / On the day of the defence date the status of article V was In Press.
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A Technical and Clinical Assessment of Stereotactic Registration Techniques to Improve MRI Guided Needle Navigation in Prostate Cancer TargetingSuljendic, Denis 15 February 2010 (has links)
Prostate cancer is prevalent among men and one of the few cancer sites where local therapies currently target the entire organ instead of tumour. MRI holds promise in accurately depicting regions of cancer burden within the prostate gland and guiding tumour-targeted diagnostics and therapeutics. The clinical performance of a novel stereotactic MRI-guided needle navigation system for prostate cancer targeting was evaluated. Mean absolute in-plane stereotactic needle-targeting error for 10 patients was 2.2 mm and mean absolute depth error was 6.5 mm, highlighting a need to improve technical accuracy of the system. Consequently, alternative stereotactic registration techniques were investigated. Metrics of performance were in-plane stereotactic needle-targeting error, depth error, and registration time. A Z-shaped fiducial motif using automated registration performed best in phantom experiments with an in-plane error of 2.0 mm and depth error of 1.0 mm. These results will guide further software and hardware development to improve clinical performance.
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A Technical and Clinical Assessment of Stereotactic Registration Techniques to Improve MRI Guided Needle Navigation in Prostate Cancer TargetingSuljendic, Denis 15 February 2010 (has links)
Prostate cancer is prevalent among men and one of the few cancer sites where local therapies currently target the entire organ instead of tumour. MRI holds promise in accurately depicting regions of cancer burden within the prostate gland and guiding tumour-targeted diagnostics and therapeutics. The clinical performance of a novel stereotactic MRI-guided needle navigation system for prostate cancer targeting was evaluated. Mean absolute in-plane stereotactic needle-targeting error for 10 patients was 2.2 mm and mean absolute depth error was 6.5 mm, highlighting a need to improve technical accuracy of the system. Consequently, alternative stereotactic registration techniques were investigated. Metrics of performance were in-plane stereotactic needle-targeting error, depth error, and registration time. A Z-shaped fiducial motif using automated registration performed best in phantom experiments with an in-plane error of 2.0 mm and depth error of 1.0 mm. These results will guide further software and hardware development to improve clinical performance.
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Low-Level Haskell Code: Measurements and Optimization TechniquesPeixotto, David 06 September 2012 (has links)
Haskell is a lazy functional language with a strong static type system and
excellent support for parallel programming. The language features of Haskell
make it easier to write correct and maintainable programs, but execution speed
often suffers from the high levels of abstraction. While much past research
focuses on high-level optimizations that take advantage of the functional
properties of Haskell, relatively little attention has been paid to the
optimization opportunities in the low-level imperative code generated during
translation to machine code. One problem with current low-level optimizations
is that their effectiveness is limited by the obscured control flow caused by
Haskell's high-level abstractions. My thesis is that trace-based optimization
techniques can be used to improve the effectiveness of low-level optimizations
for Haskell programs. I claim three unique contributions in this work.
The first contribution is to expose some properties of low-level Haskell codes
by looking at the mix of operations performed by the selected benchmark codes
and comparing them to the low-level codes coming from traditional programming
languages. The low-level measurements reveal that the control flow is obscured
by indirect jumps caused by the implementation of lazy evaluation,
higher-order functions, and the separately managed stacks used by Haskell
programs.
My second contribution is a study on the effectiveness of a dynamic binary
trace-based optimizer running on Haskell programs. My results show that while
viable program traces frequently occur in Haskell programs the overhead
associated with maintaing the traces in a dynamic optimization system outweigh
the benefits we get from running the traces. To reduce the runtime overheads,
I explore a way to find traces in a separate profiling step.
My final contribution is to build and evaluate a static trace-based optimizer
for Haskell programs. The static optimizer uses profiling data to find traces
in a Haskell program and then restructures the code around the traces to
increase the scope available to the low-level optimizer. My results show that
we can successfully build traces in Haskell programs, and the optimized code
yields a speedup over existing low-level optimizers of up to 86%
with an average speedup of 5% across 32 benchmarks.
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Guided-Wave Superconducting Quantum Optoelectronic DevicesGhohroodi Ghamsari, Behnood 25 May 2010 (has links)
This thesis investigates a novel optoelectronic platform based on
the integration of superconductive structures, such as thin films
and micro-constrictions, with optical waveguides for ultra-fast and
ultra-sensitive devices with applications including high-speed
optical communications, quantum optical information processing, and
terahertz (THz) devices and systems.
The kinetic-inductive photoresponse of superconducting thin films
will be studied as the basic optoelectronic process underlying the
operation of these novel devices. Analytical formulation for the
non-bolometric response is presented, and experimental
photodetection in YBCO meander-line structures will be demonstrated.
A set of superconducting coplanar waveguides (CPW) are designed and
characterized, which support the operation of the devices at
microwave frequencies. Microwave-photonic devices comprising a
microwave transmission line and a light-sensitive element, such as a
meander-line structure, are designed and measured for implementation
of optically tunable microwave components.
In order to support low-loss and low-dispersion propagation of
millimeter-wave and THz signals in ultra-fast and wideband
kinetic-inductive devices, surface-wave transmission lines are
proposed, incorporating long-wavelength Surface Plasmon Polariton
(SPP) modes in planar metal-dielectric waveguides.
The theory of superconducting optical waveguides, including
analytical formulation and numerical methods, is developed in
detail. The implementation of superconducting optical waveguides is
discussed thoroughly, employing conventional dielectric-waveguide
techniques as well as optical SPP modes.
Superconductive traveling-wave photodetectors (STWPDs) are
introduced as a viable means for ultra-fast and ultra-sensitive
photodetection and photomixing. A modified transmission line
formalism is developed to model STWPDs, where light is guided
through an optical waveguide and photodetection is distributed along
a transmission line.
As an appendix, a systematic approach is developed for the analysis
of carrier transport through superconducting heterostructures and
micro-constrictions within the Bogoliubov-de Gennes (BdG) framework.
The method is applied to study the role of Andreev reflection and
Josephson-like phenomena in the current-voltage characteristics of
inhomogeneous superconducting structures. I-V characteristics are
experimentally demonstrated in YBCO micro-constrictions with
potential applications in millimeter-wave and THz devices.
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Digital Signal Processing Methods for Source Function Extraction of Piezoelectric ElementsKreuzinger, Tobias 19 August 2004 (has links)
Guided wave techniques have great potential for the structural
health monitoring of plate-like components. Previous research has
demonstrated the effectiveness of combining laser-ultrasonic
techniques with time-frequency representations to experimentally
develop the dispersion relationship of a plate; the high fidelity,
broad bandwidth and point-like nature of laser ultrasonics are
critical for the success of these results. Unfortunately, laser
ultrasonic techniques are time and cost intensive, and are
impractical for many in-service applications. Therefore this
research develops a complementary digital signal processing
methodology that uses mounted piezoelectric elements instead of
optical devices. This study first characterizes the spatial and
temporal effects of oil coupled and glued piezoelectric sources,
and then develops a procedure to interpret and model the
distortion caused by their limited bandwidth and finite size.
Furthermore, it outlines any inherent difficulties for time and
frequency domain considerations. The deconvolution theory for
source function extraction in the time - and frequency domain
under the presence of noise is provided and applied to measured
data. These considerations give the background for further studies
to develop a dispersion relationship of a plate with the fidelity
and bandwidth similar to results possible with laser ultrasonics,
but made using mounted piezoelectric sources.
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General Forms of Eigen-Mode Analysis for Multilayer Optical WaveguidesChen, Shih-yuan 05 July 2012 (has links)
In this thesis, we proposed general forms of eigen-mode analysis for multilayer optical waveguides. This study discussed the periodic structure in transverse direction and used the slowly varying envelope approximation to approximate the wave function. Firstly, we presented a general method for analyzing the multilayer nonlinear optical waveguide structure by using modal theory. The nonlinear optical waveguide is a medium whose refractive index changes with the electric field intensity. The general method can also be degenerated into some other special cases for analyzing multilayer nonlinear optical waveguide. Secondly, a general method for analyzing the multilayer optical waveguides with photonic metamaterials characterized by simultaneously negative dielectric permittivity and magnetic permeability was studied. The research pointed out explicitly that the three-layer planar waveguide with photonic metamaterials could support forbidden regions. The complete set of modes of all possible solutions for the TE wave in photonic metamaterials optical waveguide was found. The transverse electric field distributions and dispersion relations in multilayer optical waveguides can be obtained by using these general forms. Finally, we used the general forms to design an all-optical mode converter which composed of a pair of multibranch optical waveguides. The analytical and numerical results show excellent agreement.
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Research and Development of Applying Vision guided Position Control by a Flexible Circuits with Automatic Drill EquipmentsLiu, Yi-Te 26 July 2001 (has links)
Flexible printed circuits (FPCs) have a flexible character, so the topic for high accuracy and speed of drill is important. We will create an automatic system that joins vision-guided function to accomplish the challenge object of high quality and low cost. The system must contain two sub-systems, which are the machine position control and the image recognition. The machine position control system basis framework moves to position after getting hole-position with different methods and scheme of trajectory planning. The image recognition system framework exports correction to machine position control system that integrates the technique of charge-coupled device (CCD), light source design, snap an image in region of interest (ROI) with image grabber card, pattern match that uses normalized cross correlation (NCC) algorithm. We can proof that the system can achieve the expected goal of high speed and accuracy of drill.
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Applications of TAP-NDE technique to non-contact ultrasonic inspection in tubularsBaltazar-Lopez, Martin Eduardo 17 February 2005 (has links)
The possibility and feasibility of experimental detection of localized defects in tubes using laser-induced ultrasonic wave approach through Thermo Acousto Photonic Non Destructive Evaluation (TAP-NDE) and Signal processing through wavelet transform is examined in this research. Guided waves in cylindrical surfaces provide solutions for detection of different defects in the material. Several experiments were conducted to this respect. Wave propagation in both axial and circumferential directions was studied. The dispersive wave propagation of ultrasonic waves in hollow cylinders has been investigated experimentally, primarily for use in non-contact and nondestructive inspections of pipes and tubes. The laser ultrasonic waves propagated in cylindrical waveguides are particularly attractive because of their unique characteristics in the applications of nondestructive evaluation (NDE). Contrary to studies making use of only axially symmetric guided waves in hollow cylinders, here are analyzed also nonaxisymmetric waves. The analysis of data is made by using the Gabor wavelet transform. The capability of modeling the guided wave dispersion in hollow cylinders is used in developing guided wave experimental techniques for flaw detection. Good agreement was obtained when comparing the dispersion spectra between theory and experimentation. Measurement of group velocities of guided waves, which are obtained directly from the wavelet transform coefficients, can be used to determine allocation and sizing of flaws.
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Comparative study of authentic scientific research versus guided inquiry in affecting middle school students' abilities to know and do geneticsScallon, Jane Metty 16 August 2006 (has links)
This exploratory mixed methods study addressed the types of gains students made
when engaged in one of two forms of inquiry. Gains were measured on three levels:
conceptual understanding, the process of scientific investigation, and use of practical
reasoning skills. One hundred-thirty 8th grade students from a rural public school in East
Texas participated in this study. Classes of students were randomly assigned to one of
two treatment groups: guided inquiry or authentic student research learning. Non
parametric statistical analysis and constant comparative qualitative analysis were used to
triangulate pre-tests and post-tests, student journals, and student drawings to address the
research questions. Findings support greater gains in conceptual understanding of
domain specific content in a highly scaffolded guided inquiry. Further authentic
scientific research learning was more effective for developing understanding of scientific
investigation as a process and application of knowledge through practical reasoning
skills.
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