Direction finding in the presence of colored noise by candidateidentification

A method is developed for identifying correct angles of arrivals from a set of candidate angles that contains spurious angles and the true ones, under the assumption that the colored noise is an autoregressive process and that a uniform linear array of sensors is used. The procedure is based on a relation derived for the higher-order reflection coefficients corresponding to the autocorrelation sequence of the signal plus noise. It is shown that the higher-order reflection coefficients of a set of plane waves impinging on a uniform linear array of sensors, in the presence of an unknown spatially autoregressive colored noise process, are equal to an order independent linear combination of the values of the Fourier transform of the corresponding optimal linear least squares normalized prediction error filter at the electric phase angles of the plane waves. The magnitudes of the coefficients are then used to decide whether a given candidate direction of arrival corresponds to an actual plane wave or not. The estimation of candidate angles is also briefly discussed     

Geometric Invariance in image watermarking

Surviving geometric attacks in image watermarking is considered to be of great importance. In this paper, the watermark is used in an authentication context. Two solutions are being proposed for such a problem. Both geometric and invariant moments are used in the proposed techniques. An invariant watermark is designed and tested against attacks performed by StirMark using the invariant moments. On the other hand, an image normalization technique is also proposed which creates a normalized environment for watermark embedding and detection. The proposed algorithms have the advantage of being robust, computationally efficient, and no overhead needs to be transmitted to the decoder side. The proposed techniques have proven to be highly robust to all geometric manipulations, filtering, compression and slight cropping which are performed as part of StirMark attacks as well as noise addition, both Gaussian and salt & pepper.     

Anxiety and cancer treatment: Response to stressful radiotherapy.

Conducted a study with 19 White female cancer patients (aged 23–78 yrs) to document the magnitude of anxiety Ss experienced in response to one particularly stressful form of radiation treatment. In addition, the change in anxiety responses with repeated exposures and individual differences among Ss was explored. As the time for internal radiotherapy treatment neared, subjective and physiologic indicants of anxiety and distress among the Ss significantly increased. By 24 hrs posttreatment, anxiety for all Ss remained elevated. A subset of the Ss who required 2 applications of radiotherapy continued to respond negatively during the 2nd treatment. Data on individual differences in anxiety responses suggest that those with low levels of pretreatment anxiety experienced considerable disruption posttreatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Real time 3D visualization of intraoperative organ deformations using structured dictionary

Restricted visualization of the surgical field is one of the most critical challenges for minimally invasive surgery (MIS). Current intraoperative visualization systems are promising. However, they can hardly meet the requirements of high resolution and real time 3D visualization of the surgical scene to support the recognition of anatomic structures for safe MIS procedures. In this paper, we present a new approach for real time 3D visualization of organ deformations based on optical imaging patches with limited field-of-view and a single preoperative scan of magnetic resonance imaging (MRI) or computed tomography (CT). The idea for reconstruction is motivated by our empirical observation that the spherical harmonic coefficients corresponding to distorted surfaces of a given organ lie in lower dimensional subspaces in a structured dictionary that can be learned from a set of representative training surfaces. We provide both theoretical and practical designs for achieving these goals. Specifically, we discuss details about the selection of limited optical views and the registration of partial optical images with a single preoperative MRI/CT scan. The design proposed in this paper is evaluated with both finite element modeling data and ex vivo experiments. The ex vivo test is conducted on fresh porcine kidneys using 3D MRI scans with 1.2 mm resolution and a portable laser scanner with an accuracy of 0.13 mm. Results show that the proposed method achieves a sub-3 mm spatial resolution in terms of Hausdorff distance when using only one preoperative MRI scan and the optical patch from the single-sided view of the kidney. The reconstruction frame rate is between 10 frames/s and 39 frames/s depending on the complexity of the test model.     

Arithmetic coding with dual symbol sets and its performanceanalysis

We propose a novel adaptive arithmetic coding method that uses dual symbol sets: a primary symbol set that contains all the symbols that are likely to occur in the near future and a secondary symbol set that contains all other symbols. The simplest implementation of our method assumes that symbols that have appeared in the previously are highly likely to appear in the near future. It therefore fills the primary set with symbols that have occurred in the previously. Symbols move dynamically between the two symbol sets to adapt to the local statistics of the symbol source. The proposed method works well for sources, such as images, that are characterized by large alphabets and alphabet distributions that are skewed and highly nonstationary. We analyze the performance of the proposed method and compare it to other arithmetic coding methods, both theoretically and experimentally. We show experimentally that in certain contexts, e.g., with a wavelet-based image coding scheme that has appeared in the literature, the compression performance of the proposed method is better than that of the conventional arithmetic coding method and the zero-frequency escape arithmetic coding method.     

Multiresolution scene-based video watermarking using perceptualmodels

We present a watermarking procedure to embed copyright protection into digital video. Our watermarking procedure is scene-based and video dependent. It directly exploits spatial masking, frequency masking, and temporal properties to embed an invisible and robust watermark. The watermark consists of static and dynamic temporal components that are generated from a temporal wavelet transform of the video scenes. The resulting wavelet coefficient frames are modified by a perceptually shaped pseudorandom sequence representing the author. The noise-like watermark is statistically undetectable to thwart unauthorized removal. Furthermore, the author representation resolves the deadlock problem. The multiresolution watermark may be detected on single frames without knowledge of the location of the frames in the video scene. We demonstrate the robustness of the watermarking procedure to several video degradations and distortions     

A novel high-capacity data-embedding system.

In this paper, we present a novel data-embedding system with high embedding capacity. The embedding algorithm is based on the quantized projection embedding method with some enhancement to achieve high embedding rates. In particular, our system uses a random permutation of the columns of a Hadamard matrix as projection vectors and a fixed perceptual mask based on the JPEG default quantization table for the quantization step design. As a result, the data-embedding system achieves 1/167 (1 bit out of 167 raw image bits) to 1/84 hiding ratios with a BER of around 0.1% in the presence of JPEG compression attacks, while maintaining visual distortion at a minimum.     

Internal models and recursive estimation for 2-D isotropic randomfields

Efficient recursive smoothing algorithms are developed for isotropic random fields that can be obtained by passing white noise through rational filters. The estimation problem is shown to be equivalent to a countably infinite set of 1-D separable two-point boundary value smoothing problems. The 1-D smoothing problems are solved using a Markovianization approach followed by a standard 1-D smoothing algorithm. The desired field estimate is then obtained as properly weighted sum of the 1-D smoothed estimates. The 1-D two-point boundary value problems are also shown to have the same asymptotic properties and yield a stable spectral factorization of the power spectrum of the isotropic random fields     

A class of piecewise linear differential equations arising in biological models

We investigate the properties of the solutions of a class of piecewise-linear differential equations. The equations are appropriate to model biological systems (e.g. genetic networks) in which there are switch-like interactions between the elements. The analysis uses the concept of Filippov solutions of differential equations with a discontinuous right-hand side. It gives an insight into the so-called singular solutions which lie on the surfaces of discontinuity. We show that this notion clarifies the study of several examples studied in the literature.     

Sleep-disordered breathing in children with myelomeningocele

BACKGROUND: Although patients with myelomeningocele and the Chiari II malformation are known to have sleep apnea and respiratory control deficits, the prevalence, types, severities, and associations of sleep-disordered breathing (SDB) have not been adequately defined. METHODS: A cross-sectional study of our myelomeningocele clinic population was undertaken to correlate polysomnographic results with historical data and findings from magnetic resonance imaging of the Chiari malformation, pulmonary function results, and nocturnal pulse oximetry. RESULTS: A questionnaire survey of symptoms was available for 107 of 109 children (98% of the clinic population), and 83 patients agreed to undergo overnight polysomnography. Breathing during sleep was classified as normal in 31 cases (37%), mildly abnormal in 35 cases (42%), and moderately/severely abnormal in 17 cases (20%). Among the 17 patients with moderately/severely abnormal SDB, 12 patients had predominantly central apneas and 5 had predominantly obstructive apnea. Patients with a thoracic or thoracolumbar myelomeningocele, those who had previously had a posterior fossa decompression operation, those with more severe brain-stem malformations, and those with pulmonary function abnormalities were more likely to have moderately/severely abnormal SDB, relative risks (95% confidence intervals) 9.2 (2.9 to 29.3), 3.5 (1.3 to 8.9), 3.0 (0.9 to 10.5), and 11.6 (1.6 to 81.3), respectively. Failure of obstructive SDB to resolve after adenotonsillectomy in four patients suggested abnormal control of pharyngeal airway patency during sleep. Nocturnal pulse oximetry accurately predicted moderately/severely abnormal SDB with a sensitivity of 100% and a specificity of 67%. CONCLUSIONS: The pathogenesis of SDB in patients with myelomeningocele involves the functional level of the spinal lesions, congenital and acquired brainstem abnormalities, pulmonary function abnormalities, disorders of upper airway maintenance, and sleep state. Polysomnography and nocturnal pulse oximetry should be performed in high-risk patients to detect and classify SDB.