Current Issue : July - September Volume : 2013 Issue Number : 3 Articles : 6 Articles
Electrophysiological signals such as the EEG, MEG, or LFPs have been extensively studied over the last decades, and elaborate signal\r\nprocessing algorithms have been developed for their analysis. Many of these methods are based on time-frequency decomposition\r\nto account for the signals� spectral properties while maintaining their temporal dynamics. However, the data typically exhibit\r\nintra- and interindividual variability. Existing algorithms o?en do not take into account this variability, for instance by using\r\n??xed frequency bands. ?is shortcoming has inspired us to develop a new robust and ??exible method for time-frequency analysis\r\nand signal feature extraction using the novel smooth natural Gaussian extension (snaGe) model. ?e model is nonlinear, and its\r\nparameters are interpretable. We propose an algorithm to derive initial parameters based on dynamic programming for nonlinear\r\n??tting and describe an iterative re??nement scheme to robustly ??t high-order models. We further present distance functions to be\r\nable to compare different instances of our model. ?e method�s functionality and robustness are demonstrated using simulated as\r\nwell as real data. ?e snaGe model is a general tool allowing for a wide range of applications in biomedical data analysis....
Automatic detection of lung nodules is an important problem in computer analysis of chest radiographs. In this paper, we propose\r\na novel algorithm for isolating lung abnormalities (nodules) fromspiral chest low-dose CT (LDCT) scans.The proposed algorithm\r\nconsists of three main steps. The first step isolates the lung nodules, arteries, veins, bronchi, and bronchioles from the surrounding\r\nanatomical structures. The second step detects lung nodules using deformable 3D and 2D templates describing typical geometry\r\nand gray-level distribution within the nodules of the same type. The detection combines the normalized cross-correlation template\r\nmatching and a genetic optimization algorithm. The final step eliminates the false positive nodules (FPNs) using three features that\r\nrobustly define the true lung nodules. Experiments with 200 CT data sets show that the proposed approach provided comparable\r\nresults with respect to the experts....
Photoacoustic imaging (PAI) has been employed to reconstruct endogenous optical contrast present in tissues. At the cost of\r\nlonger calculations, a compressive sensing reconstruction scheme can achieve artifact-free imaging with fewer measurements. In\r\nthis paper, an effective acceleration framework using the alternating direction method (ADM) was proposed for recovering images\r\nfrom limited-view and noisy observations. Results of the simulation demonstrated that the proposed algorithm could perform\r\nfavorably in comparison to two recently introduced algorithms in computational efficiency and data fidelity. In particular, it ran\r\nconsiderably faster than these two methods. PAI with ADM can improve convergence speed with fewer ultrasonic transducers,\r\nenabling a high-performance and cost-effective PAI system for biomedical applications....
Generalized diffusion tensor imaging (GDTI) was developed to model complex apparent diffusivity coefficient (ADC) using\r\nhigher-order tensors (HOTs) and to overcome the inherent single-peak shortcoming of DTI. However, the geometry of a complex\r\nADC profile does not correspond to the underlying structure of fibers. This tissue geometry can be inferred from the shape of the\r\nensemble average propagator (EAP). Though interesting methods for estimating a positive ADC using 4th-order diffusion tensors\r\nwere developed, GDTI in general was overtaken by other approaches, for example, the orientation distribution function (ODF),\r\nsince it is considerably difficult to recuperate the EAP from a HOT model of the ADC in GDTI. In this paper, we present a novel\r\nclosed-formapproximation of the EAP using Hermite polynomials from a modified HOT model of the original GDTI-ADC. Since\r\nthe solution is analytical, it is fast, differentiable, and the approximation converges well to the true EAP. This method also makes\r\nthe effort of computing a positive ADC worthwhile, since now both the ADC and the EAP can be used and have closed forms.We\r\ndemonstrate our approach with 4th-order tensors on synthetic data and in vivo human data....
Hydraphiles are a class of synthetic ion channels that now have a twenty-year history of analysis and success. In early studies,\r\nthese compounds were rigorously validated in a wide range of in vitro assays including liposomal ion ??ow detected by N??R\r\nor ion-selective electrodes, as well as biophysical experiments in planar bilayers. During the past decade, biological activity was\r\nobserved for these compounds including toxicity to bacteria, yeast, and mammalian cells due to stress caused by the disruption of\r\nion homeostasis. ?e channel mechanism was veri??ed in cells using membrane polarity sensitive dyes, as well as patch clamping\r\nstudies. ?is body of work has provided a solid foundation with which hydraphiles have recently demonstrated acute biological\r\ntoxicity in the muscle tissue of living mice, as measured by whole animal ??uorescence imaging and histological studies. Here we\r\nreview the critical structure-activity relationships in the hydraphile family of compounds and the in vitro and in cellulo experiments\r\nthat have validated their channel behavior. ?is report culminates with a description of recently reported efforts in which these\r\nmolecules have demonstrated activity in living mice....
For the structure mechanics of human body, it is almost impossible to conduct mechanical experiments. Then the finite element\r\nmodel to simulate mechanical experiments has become an effective tool. By introducing several common methods for constructing\r\na 3Dmodel of cranial cavity, this paper carries out systematically the research on the influence law of cranial cavity deformation. By\r\nintroducing the new concepts and theory to develop the 3D cranial cavity model with the finite-element method, the cranial cavity\r\ndeformation process with the changing ICP can be made the proper description and reasonable explanation. It can provide reference\r\nfor getting cranium biomechanical model quickly and efficiently and lay the foundation for further biomechanical experiments and\r\nclinical applications....
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