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IDENTIFIABILITY OF THE PARAMETERS OF A NONLINEAR MODEL OF THE CEREBROSPINAL FLUID SYSTEM

IFAC Proceedings Volumes 2007年第12期40卷 987-992页

作者： I.R. Manchester K.S. Andersson A. Eklund A.S. Shiriaev Department of Applied Physics and Electronics Umeå University SE-901 87 Sweden Department of Biomedical Engineering and Informatics Umeå University Hospital SE-901 85 Sweden Department of Radiation Sciences Umeå University SE-901 87 Sweden Centre of Biomedical Engineering and Physics Umeå University SE-901 87 Sweden Department of Engineering Cybernetics Norwegian University of Science and Technology N-7491 Trondheim Norway

Accurate estimates of the compliance and outflow resistance of the human cerebrospinal fluid system are important for diagnosis of a medical condition known as hydrocephalus. In this paper we study the mathematical structure of a commonly used nonlinear model, and determine what classes of inputs are required to identify its parameters. We show theoretical and simulation results supporting a claim that it is possible to greatly improve on the inputs used in current clinical practice.

关键词： Nonlinear observers biomedical systems Parameter estimation

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Experimental study on effects of nanoparticle TiO2-xNx on inactivation of leukemic HL60 cells in vitro based on ALA-PDT

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Guangdianzi Jiguang/Journal of Optoelectronics Laser 2007年第10期18卷 1265-1268页

作者： Chen, Li Xiong, Jian-Wen Liu, Gui-Xiang Zhang, Zhen-Xi School of Physics and Optoelectronic Engineering Guangdong University of Technology Guangzhou 510006 China Department of Physics South China Normal University Guangzhou 510006 China Department of Bio-medical Engineering University of Applied Sciences in Wilhelmshaven Wilhelmshaven 26389 Germany Key Laboratory of Biomedical Information Engineering School of Life Science and Technology Xi'an Jiaotong University Xi'an 710049 China

In order to study the effects of nanoparticle TiO2-xNx on the inactivation of Leukemic HL60 cells in vitro by use of 5-aminolevulinic acid (ALA) based on photodynamic therapy (PDT), the 3-(4, 5-dimethyll-2-thiazolyl)-2-5diphenyl-2H-tetrazolium bromide (MTT) assay was used to evaluate the effects of nanoparticle TiO2-xNx on the growth of Leukemic HL60, the effects of nanoparticle TiO2-xNx with different concentrations on the relative survival rate of Leukemic HL60 after PDT and the relative survival rate of Leukemic HL60 based on ALA and PDT (ALA-PDT) by adding nanoparticle TiO2-xNx. The results indicated that the nanoparticle TiO2-xNx had an obvious inactivation to Leukemic HL60 cells when its final concentration was between 50 μg/mL and 250 μg/mL;and the 150 μg/mL was the best concentration especially a-mong them. ALA-PDT based on a suitable concentration of nanoparticle TiO2-xNx could improve the efficiency of inactivation of Leukemic HL60 cells;the relative survival rate of Leukemic HL60 cells was the least after PDT based on both ALA and TiO2-xNx.

关键词： Nanoparticles

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P6H-6 Lead-Free Piezoelectric Ceramics for High-Frequency Ultrasound Transducers

P6H-6 Lead-Free Piezoelectric Ceramics for High-Frequency Ul...

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IEEE Symposium (IUS) Ultrasonics

作者： D. W. Wu R. M. Chen Q. F. Zhou D. M. Lin H. L. W. Chan K. K. Shung Department of Biomedical Engineering University of Southern California Los Angeles CA USA Department of Applied Physics Hong Kong Polytechnic University Kowloon Hong Kong China

This paper presents the latest development of lead-free piezoelectric ceramics and their application to the high frequency ultrasound transducers. Three kinds of lead-free piezoelectric ceramics [(K 0.5 Na 0.5 ) 0.9 Li 0.03 (Nb 0.9 Ta 0.1 )O 3 , K 0.5 Na 0.5 (Nb 0.94 Sb 0.06 )O 3 + 0.5mol%MnO 2 and K 0.5 Na 0.5 NbO 3 + 0.5mol%MnO 2 ] were fabricated and characterized. High frequency (40 MHz) ultrasound transducers were successfully fabricated with these ceramics. The performance of the transducers were evaluated and compared with transducers fabricated from lead-based materials. The results suggest that lead-free piezoelectric materials in some degree may serve as an alterative to lead-based piezoelectric materials for high-frequency ultrasonic transducer applications.

关键词： Environmentally friendly manufacturing techniques Ceramics Ultrasonic imaging Piezoelectric transducers Ultrasonic transducers Piezoelectric materials Frequency Fabrication Crystalline materials biomedical transducers

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Towards the simultaneous on-line estimation of the compliance and outflow resistance of the cerebrospinal fluid system

Towards the simultaneous on-line estimation of the complianc...

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European Control Conference (ECC)

作者： Ian R. Manchester Kennet S. Andersson Anders Eklund Anton S. Shiriaev Department of Applied Physics and Electronics Department of Radiation Sciences Umeå University Sweden Department of Biomedical Engineering and Informatics Umeå University Hospital Sweden Department of Engineering Cybernetics Norwegian University of Science and Technology Trondheim Norway

Accurate estimates of the compliance and outflow resistance of the human cerebrospinal fluid system are important for diagnosis of a medical condition known as hydrocephalus. In this paper we design an observer which provides simultaneous on-line estimates of the outflow resistance and compliance, to our knowledge the first method to do so. It's performance is experimentally verified using the same apparatus used to perform actual patient diagnoses and a specially designed physical model of the human cerebrospinal fluid system.

关键词： Mathematical model Immune system Equations Estimation Frequency estimation biomedical measurement Cavity resonators

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A weighted k-nearest neighbor method for gene ontology based protein function prediction

A weighted k-nearest neighbor method for gene ontology based...

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2nd International Multi-Symposiums on Computer and Computational Sciences 2007, IMSCCS'07

作者： Kharsikar, Saket Mugler, Dale Sheffer, Daniel Moore, Francisco Duan, Zhong-Hui Department of Biomedical Engineering University of Akron Akron OH 44236 United States Department of Theoretical and Applied Mathematics University of Akron Akron OH 44236 United States Integrated Bioscience PhD Program University of Akron Akron OH 44236 United States Department of Biology University of Akron Akron OH 44236 United States Department of Computer Science University of Akron Akron OH 44236 United States

ISBN: (纸本)0769530397

Numerous genome projects have produced a large and ever increasing amount of genomic sequence data. However, the biological functions of many proteins encoded by the sequences remain unknown. Protein function annotation and prediction become an essential and challenging task of post-genomic research. In this paper, we present an automated protein function prediction system based on a set of proteins of known biological functions. The functions of the proteins are characterized with gene ontology (GO) annotations. The prediction system uses a novel measure to calculate the pair-wise overall similarity between protein sequences. The protein function prediction is performed based on the GO annotations of similar sequences using a weighted k-nearest neighbor method. We show the prediction accuracies obtained using the model organism yeast (Sacchyromyces cerevisiae). The results indicate that the weighted k-nearest neighbor method significantly outperforms the regular k-nearest neighbor method for protein molecular function prediction. © 2007 IEEE.

关键词： Proteins

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Experimental Testing of a Method for On-Line Identification of the Cerebrospinal Fluid System

Experimental Testing of a Method for On-Line Identification ...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Ian R. Manchester Kennet S. Andersson Anders Eklund Anton S. Shiriaev Department of Applied Physics and Electronics Sweden Department of Radiation Sciences Umea University Sweden Department of Biomedical Engineering and Informatics Umea University Hospital Sweden Department of Engineering Cybernetics Norwegian University of Science and Technology Trondheim Norway

Accurate estimates of the compliance and outflow resistance of the human cerebrospinal fluid system are important for diagnosis of a medical condition known as hydrocephalus. In this paper we present a system which provides simultaneous on-line estimates of the outflow resistance and compliance. It's performance is experimentally verified using the same apparatus used to perform actual patient diagnoses and a specially designed physical model of the human cerebrospinal fluid system.

关键词： System testing Immune system Surgery Humans biomedical engineering Hospitals Medical tests Medical conditions Medical diagnosis Hydrodynamics

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Sensing metabolic activity in tissue engineered constructs

Sensing metabolic activity in tissue engineered constructs

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European Conference on biomedical Optics, ECBO 2007

作者： Chandra, Malavika Wilson, Robert H. Lo, Wen-Liang Vishwanath, Karthik Izumi, Kenji Feinberg, Stephen E. Mycek, Mary-Ann Applied Physics Program University of Michigan Ann Arbor MI 48109 United States Oral and Maxillofacial Surgery University of Michigan Ann Arbor 48109 United States Dept. of Biomedical Engineering University of Michigan Ann Arbor MI 48109 United States Comprehensive Cancer Center University of Michigan Medical School Ann Arbor MI 48109 United States

ISBN: (纸本)9780819467713

Tissue engineered constructs can be employed to graft wounds or replace diseased tissue. Non-invasive methods are required to assess cellular viability in these constructs both pre-and post-implantation into patients. In this study, Monte Carlo simulations and fluorescence experiments were executed on ex vivo produced oral mucosa equivalent (EVPOME) constructs to investigate the fluorescence emitted at 355 nm excitation from these constructs. Both simulations and experiments indicated the need to investigate alternative excitation wavelengths in order to increase the cellular fluorescence from these constructs, while decreasing contributions from extra-cellular fluorophores. © 2007 SPIE-OSA.

关键词： Tissue engineering

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Strongly nonlinear behavior of granular chains and granular composites

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The Journal of the Acoustical Society of America 2008年第5_SUPPLEMENT期123卷 3271-3271页

作者： Vitali F. Nesterenko Eric B. Herbold David J. Benson Jeonghoon Kim Chiara Daraio University of California San Diego 9500 Gilman Drive Department of Mechanical and Aerospace Engineering La Jolla CA 92093‐0411 USA vnesterenko@ucsd.edu University of California San Diego 9500 Gilman Drive Department of Mechanical and Aerospace Engineering La Jolla CA 92093‐0411 USA eherbold@*** University of California San Diego 9500 Gilman Drive Department of Mechanical and Aerospace Engineering La Jolla CA 92093‐0411 USA dbenson@ucsd.edu University of California San Diego 9500 Gilman Drive Materials Science and Engineering Program La Jolla CA 92093 USA jek008@ucsd.edu California Institute of Technology Aeronautics (GALCIT) and Applied Physics Pasadena CA 91125 USA daraio@caltech.edu

Strongly nonlinear behavior of granular phononic crystals composed of stainless steel cylinders and PTFE spheres is considered experimentally and numerically. The tenability of phononic band gap in this two‐mass prestressed chain was investigated. The results show that the phononic band gap exists within audible frequency regime (20–20,000 Hz) and can be tuned by changing the value of prestress. Influence of the weak and strong nonlinearity on the propagation of signals with frequencies inside band gap was investigated. The mechanical properties of reactive materials (e.g., high density mixtures of polytetraflouroethylene (PTFE), aluminum (Al) and tungsten (W) powders) where unconsolidated granular packing of metal particles plays significant role in the dynamic behavior was investigated. It was found that dynamic strength can be tailored by changing the morphology of the particles and porosity. Cold isostatically pressed PTFE‐Al‐W powder composites with fine metallic particles and a higher porosity exhibited higher ultimate compressive strength than less porous composites having equivalent mass ratios with coarse W particles. Based on the numerical analysis it was concluded that a mesoscale force chains between the fine metallic particles are responsible for this unusual phenomenon. This work was supported by the NSF DCMS03013220 and by MURI ONR N00014‐07‐1‐0740.

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Limiting Iterations vs. Post Smoothing for Noise Control in PET

Limiting Iterations vs. Post Smoothing for Noise Control in ...

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2007 IEEE Nuclear Science Symposium Conference (NSS 2007), vol.7

作者： Timothy G. Turkington Joshua M. Wilson James E. Bowsher David R. Gilland Department of Biomedical Engineering Duke University Durham NC USA Graduate Program in Medical Physics Duke University Durham NC USA Department of Radiation Oncology Graduate Program in Medical Physics Duke University Durham NC 27710 USA Department of Nuclear and Radiological Engineering University of Florida Gainesville FL USA

We have performed physical phantom and simulation study with PET to compare the effects of limiting iterations and post-smoothing. The phantom was designed to mimic small hot lesions typical in FDG PET. The phantom was a body-sized 25L phantom. Eight 1cm hot spheres were filled with activity 8x the background. The phantom was scanned in 2D for 15 minutes on a GE Discovery STE. Data were framed into 1, 3, 5, and 15min frames. Images were reconstructed with a variety of subset sizes and up to 60 iterations, with corrections for attenuation, scatter, randoms, and dead-time. All image sets were post-smoothed with 4, 6, 8, 10, and 12mm FWHM Gaussian. ROI's were placed on all hot spheres, and 40 additional background ROI's were placed. Noise was measured as the variation in background ROI's. Additionally, noise was measured on a pixel-by-pixel basis as the variation over the ensemble of realizations of each frame time. Noise vs. contrast (sphere-background) were plotted for each image. The background noise method showed better results for limited iterations (～20% lower noise at a given contrast level) while the ensemble-based noise method favored post-smoothing of high iterations (with a similar ～20% difference). Similar results were obtained for simulations.

关键词： Smoothing methods Positron emission tomography Imaging phantoms Background noise Noise measurement Noise level Lesions Image reconstruction Attenuation Scattering

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Breast mass detection in tomosynthesis projection images using information-theoretic similarity measures

Breast mass detection in tomosynthesis projection images usi...

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Medical Imaging 2007: Computer-Aided Diagnosis

作者： Singh, Swatee Tourassi, Georgia D. Lo, Joseph Y. Department of Biomedical Engineering Duke University Medical Center Duke University 2424 Erwin Road Durham NC 27705 Duke Medical Physics Program Duke University Medical Center Duke University 2424 Erwin Road Durham NC 27705 Department of Radiology Duke University Medical Center Duke University 2424 Erwin Road Durham NC 27705

ISBN: (纸本)0819466328

The purpose of this project is to study Computer Aided Detection (CADe) of breast masses for digital tomosynthesis. It is believed that tomosynthesis will show improvement over conventional mammography in detection and characterization of breast masses by removing overlapping dense fibroglandular tissue. This study used the 60 human subject cases collected as part of on-going clinical trials at Duke University. Raw projections images were used to identify suspicious regions in the algorithm's high-sensitivity, low-specificity stage using a Difference of Gaussian (DoG) filter. The filtered images were thresholded to yield initial CADe hits that were then shifted and added to yield a 3D distribution of suspicious regions. These were further summed in the depth direction to yield a flattened probability map of suspicious hits for ease of scoring. To reduce false positives, we developed an algorithm based on information theory where similarity metrics were calculated using knowledge databases consisting of tomosynthesis regions of interest (ROIs) obtained from projection images. We evaluated 5 similarity metrics to test the false positive reduction performance of our algorithm, specifically joint entropy, mutual information, Jensen difference divergence, symmetric Kullback-Liebler divergence, and conditional entropy. The best performance was achieved using the joint entropy similarity metric, resulting in ROC A2 of 0.87 ±0.01. As a whole, the CADe system can detect breast masses in this data set with 79% sensitivity and 6.8 false positives per scan. In comparison, the original radiologists performed with only 65% sensitivity when using mammography alone, and 91% sensitivity when using tomosynthesis alone.

关键词： Tumors

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