Compression of color skin tumor images with vector quantization.
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Algorithms↗
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Adaptive homogeneity-directed demosaicing algorithm.
A cost-effective digital camera uses a single-image sensor, applying alternating patterns of red, green, and blue color filters to each pixel location. A way to reconstruct a full three-color representation of color images by estimating the missing pixel components in each color plane is called a demosaicing algorithm. This paper presents three inherent problems often associated with demosaicing algorithms that incorporate two-dimensional (2-D) directional interpolation: misguidance color artifacts, interpolation color artifacts, and aliasing. The level of misguidance color artifacts present in two images can be compared using metric neighborhood modeling. The proposed demosaicing algorithm estimates missing pixels by interpolating in the direction with fewer color artifacts. The aliasing problem is addressed by applying filterbank techniques to 2-D directional interpolation. The interpolation artifacts are reduced using a nonlinear iterative procedure. Experimental results using digital images confirm the effectiveness of this approach.
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LV shape and motion: B-spline-based deformable model and sequential motion decomposition.
In this paper, we extend a previous work by J. Park and propose a uniform framework to reconstruct left ventricle (LV) geometry/motion from tagged MR images. In our work, the LV is modeled as a generalized prolate spheroid, and its motion is decomposed into four components-global translation, polar radial/z-axis compression, twisting, and bending. By formulating model parameters as tensor products of B-splines, we develop efficient algorithms to quickly reconstruct LV geometry/motion from extracted boundary contours and tracked planar tags. Experiments on both synthesized and in vivo data are also reported.
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Decomposition of protein experimental compressibility into intrinsic and hydration shell contributions.
The experimental determination of protein compressibility reflects both the protein intrinsic compressibility and the difference between the compressibility of water in the protein hydration shell and bulk water. We use molecular dynamics simulations to explore the dependence of the isothermal compressibility of the hydration shell surrounding globular proteins on differential contributions from charged, polar, and apolar protein-water interfaces. The compressibility of water in the protein hydration shell is accounted for by a linear combination of contributions from charged, polar, and apolar solvent-accessible surfaces. The results provide a formula for the deconvolution of experimental data into intrinsic and hydration contributions when a protein of known structure is investigated. The physical basis for the model is the variation in water density shown by the surface-specific radial distribution functions of water molecules around globular proteins. The compressibility of water hydrating charged atoms is lower than bulk water compressibility, the compressibility of water hydrating apolar atoms is somewhat larger than bulk water compressibility, and the compressibility of water around polar atoms is about the same as the compressibility of bulk water. We also assess whether hydration water compressibility determined from small compound data can be used to estimate the compressibility of hydration water surrounding proteins. The results, based on an analysis from four dipeptide solutions, indicate that small compound data cannot be used directly to estimate the compressibility of hydration water surrounding proteins.
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Independent component analysis applied to feature extraction from colour and stereo images.
Previous work has shown that independent component analysis (ICA) applied to feature extraction from natural image data yields features resembling Gabor functions and simple-cell receptive fields. This article considers the effects of including chromatic and stereo information. The inclusion of colour leads to features divided into separate red/green, blue/yellow, and bright/dark channels. Stereo image data, on the other hand, leads to binocular receptive fields which are tuned to various disparities. The similarities between these results and the observed properties of simple cells in the primary visual cortex are further evidence for the hypothesis that visual cortical neurons perform some type of redundancy reduction, which was one of the original motivations for ICA in the first place. In addition, ICA provides a principled method for feature extraction from colour and stereo images; such features could be used in image processing operations such as denoising and compression, as well as in pattern recognition.
Algorithms↗
The Pennsylvania Plan. An algorithm for the management of lumbar degenerative disc disease.
An algorithm for the sequential management of the patient with low-back pain has been formulated from evaluation of treatment outcomes. Patients presenting with back pain complaints and cauda equina syndrome are evaluated with immediate myelography. Without this complication, back pain patients are treated with 6 weeks of conservative therapy. Those who fail to respond are evaluated with progressively more complex techniques. When sciatica predominates, treatment may ultimately include laminectomy. When back pain predominates, medical and psychosocial appraisal are recommended. Some with normal medical and psychosocial evaluations may become candidates for spine fusion. The remaining are treated according to the findings of such appraisals. Rigorous screening is mandatory prior to any surgery.
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Acute low back problems in adults: assessment and treatment. Agency for Health Care Policy and Research.
This Quick Reference Guide for Clinicians contains highlights from the Clinical Practice Guideline version of Acute Low Back Problems in Adults, which was developed by a private-sector panel of health care providers and consumers. The Quick Reference Guide is an example of how a clinician might implement the panel's findings and recommendations on the management of acute low back problems in working-age adults. Topics covered include the initial assessment of patients presenting with acute low back problems, identification of red flags that may indicate the presence of a serious underlying medical condition, initial management, special studies and diagnostic considerations, and further management considerations. Instructions for clinical testing for sciatic tension, recommendations for sitting and unassisted lifting, tests for identification of clinical pathology, and algorithms for patient management are included.
Acute Disease↗
System for efficient and secure distribution of medical images on the Internet.
Because of the high compressibility of the medical images, data compression is desirable for digital storage despite the availability of inexpensive hardware for mass storage. A progressive transmission algorithm with automatic security filtering features for on-line medical image distribution using Daubechies' wavelets has been developed and is discussed in this paper. The system is practical for real-world applications, processing and coding each 12-bit image of size 512 x 512 within 2 seconds on a Pentium Pro. Besides its exceptional speed, the security filter has demonstrated a remarkable accuracy in detecting sensitive textual information within current or digitized previous medical images. The algorithm is of linear run time.
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Oncologic emergencies.
The prognosis for the child with cancer has improved dramatically over the past decades. With this success comes the need for recognition and proper treatment of emergencies. Respiratory or circulatory failure may arise from compression of the SVC or airway. Epidural spinal cord compression by tumor may lead to irreversible paraplegia or urinary incontinence if intervention is not rapid. Raised intracranial pressure may be a life-threatening presentation of a brain tumor. Bone marrow failure, with anemia and thrombocytopenia, is associated with malignant infiltration of the marrow. Hyperleukocytosis carries a high risk of thrombotic events if not treated promptly. Coagulation abnormalities are seen in many childhood cancers at the time of diagnosis. Life-threatening metabolic abnormalities are observed at presentation in children with leukemia and lymphoma. Hypercalcemia, although rare, may be a difficult situation to correct. Immediate attention to these emergencies and appropriate treatment may save the life of a child with cancer or make his or her subsequent course just a little smoother.
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A block coding method that leads to significantly lower entropy values for the proteins and coding sections of Haemophilus influenzae.
A simple statistical block code in combination with the LZW-based compression utilities gzip and compress has been found to increase by a significant amount the level of compression possible for the proteins encoded in Haemophilus influenzae, the first fully sequenced genome. The method yields an entropy value of 3.665 bits per symbol (bps), which is 0.657 bps below the maximum of 4.322 bps and an improvement of 0.452 bps over the best known to date of 4.118 bps using Matsumoto, Sadakane, and Imai's lza-CTW algorithm. Calculations based on a compact inverse genetic code show that the genome has a maximum entropy of 1.757 bps for the coding regions, with a possibly lower actual entropy. These results hint at the existence of hitherto unexplored redundancies that do not show up in Markov models and are indicative of more internal structure than suspected in both the protein and the genome.
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Improved method for predicting beta-turn using support vector machine.
MOTIVATION: Numerous methods for predicting beta-turns in proteins have been developed based on various computational schemes. Here, we introduce a new method of beta-turn prediction that uses the support vector machine (SVM) algorithm together with predicted secondary structure information. Various parameters from the SVM have been adjusted to achieve optimal prediction performance. RESULTS: The SVM method achieved excellent performance as measured by the Matthews correlation coefficient (MCC = 0.45) using a 7-fold cross validation on a database of 426 non-homologous protein chains. To our best knowledge, this MCC value is the highest achieved so far for predicting beta-turn. The overall prediction accuracy Qtotal was 77.3%, which is the best among the existing prediction methods. Among its unique attractive features, the present SVM method avoids overtraining and compresses information and provides a predicted reliability index.
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Neuromonitoring of cochlea and auditory nerve with multiple extracted parameters during induced hypoxia and nerve manipulation.
A system capable of comprehensive and detailed monitoring of the cochlea and the auditory nerve during intraoperative surgery was developed. The cochlear blood flow (CBF) and the electrocochleogram (ECochGm) were recorded at the round window (RW) niche using a specially designed otic probe. The ECochGm was further processed to obtain cochlear microphonics (CM) and compound action potentials (CAP). The amplitude and phase of the CM were used to quantify the activity of outer hair cells (OHC); CAP amplitude and latency were used to describe the auditory nerve and the synaptic activity of the inner hair cells (IHC). In addition, concurrent monitoring with a second electrophysiological channel was achieved by recording compound nerve action potential (CNAP) obtained directly from the auditory nerve. Stimulation paradigms, instrumentation and signal processing methods were developed to extract and differentiate the activity of the OHC and the IHC in response to three different frequencies. Narrow band acoustical stimuli elicited CM signals indicating mainly nonlinear operation of the mechano-electrical transduction of the OHCs. Special envelope detectors were developed and applied to the ECochGm to extract the CM fundamental component and its harmonics in real time. The system was extensively validated in experimental animal surgeries by performing nerve compressions and manipulations.
Action Potentials↗
Multiple focusing with adaptive time-reversal mirror.
Recently, adaptivity was introduced to time-reversal mirror to steer the nulls, and referred to as an adaptive time-reversal mirror (ATRM) [J. S. Kim, H. C. Song, and W. A. Kuperman, J. Acoust. Soc. Am. 109, 1817-1825 (2001)]. In this study, ATRM is extended to simultaneous multiple focusing in an ocean waveguide. The multiple focusing is achieved by imposing a set of constraints in the formulation to find the weight vectors. The algorithm is applied to the long-range underwater acoustic communication to show, via simulation, that the simultaneous pulse compression at multiple receiving locations is achieved.
Journal Article↗
Spectral contrast enhancement of speech in noise for listeners with sensorineural hearing impairment: effects on intelligibility, quality, and response times.
This paper describes a series of experiments evaluating the effects of digital processing of speech in noise so as to enhance spectral contrast, using subjects with cochlear hearing loss. The enhancement was carried out on a frequency scale related to the equivalent rectangular bandwidths (ERBs) of auditory filters in normally hearing subjects. The aim was to enhance major spectral prominences without enhancing fine-grain spectral features that would not be resolved by a normal ear. In experiment 1, the amount of enhancement and the bandwidth (in ERBs) of the enhancement processing were systematically varied. Large amounts of enhancement produced decreases in the intelligibility of speech in noise. Performance for moderate degrees of enhancement was generally similar to that for the control conditions, possibly because subjects did not have sufficient experience with the processed speech. In experiment 2, subjects judged the relative quality and intelligibility of speech in noise processed using a subset of the conditions of experiment 1. Generally, processing with a moderate degree of enhancement was preferred over the control condition, for both quality and intelligibility. Subjects varied in their preferences for high degrees of enhancement. Experiment 3 used a modified processing algorithm, with a moderate degree of spectral enhancement, and examined the effects of combining the enhancement with dynamic range compression. The intelligibility of speech in noise improved with practice, and, after a small amount of practice, scores for the condition combining enhancement with a moderate degree of compression were found to be significantly higher than for the control condition. Experiment 4 used a subset of conditions from experiment 3, but performance was assessed using a sentence verification test that measured both intelligibility and response times. Scores on both measures were improved by spectral enhancement, and improved still more by enhancement combined with compression. The effects were statistically more robust for the response times. When expressed as equivalent changes in speech-to-noise ratio, the improvements were about twice as large for the response times as for the intelligibility scores. The overall effect of spectral enhancement combined with compression was equivalent to an improvement of speech-to-noise ratio by 4.2 dB.
Adult↗
Treatment of patients with spinal metastases from head and neck neoplasms.
BACKGROUND: Spinal metastases are uncommon in patients with advanced head and neck cancer. Treatment strategies in this patient group have not been defined. Although it has been established that neurologic dysfunction in patients with spinal metastases and cord compression constitutes an oncologic emergency, the role of surgical treatment remains controversial. OBJECTIVE: To clarify the treatment options in patients with head and neck cancer who develop spinal metastases. METHODS: The clinical course of patients seen at our institution with head and neck neoplasms and spinal metastases from January 1992 to January 2000 was reviewed. RESULTS: Eleven patients were identified. Nine developed spinal metastases more than 3 months after the diagnosis of advanced head and neck cancer. The other 2 presented with synchronous spinal involvement and skull base neoplasms. Patients without neurologic symptoms were offered intravenous steroids and palliative radiation. Patients with neurologic symptoms were treated with either intravenous steroids and radiation or surgical decompression and spinal fusion. In 1 patient, no improvement occurred within the first 2 days of radiotherapy, and the patient underwent surgical decompression. Patients with an unstable spine underwent surgical decompression and spinal fusion. Patients with a life expectancy of more than 6 months and neurologic symptoms were offered surgical therapy. In the 9 patients with advanced cancer, the average survival time was 3 months. Two of these patients have survived longer than 6 months. CONCLUSIONS: We propose that surgical decompression is a viable, justifiable option for selected patients with advanced head and neck cancer and spinal cord compression. Furthermore, we recommend surgical decompression as a first option in patients with an unstable bony spine and/or in whom survival is expected to be longer than 6 months. Finally, we propose a patient management algorithm in these cases.
Adult↗
The application of wavelets to retinal image compression and its effect on automatic microaneurysm analysis.
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Algorithms↗
Evaluating the effect of co-contraction in optimization models.
The effect of co-contraction of antagonist muscles on spinal compression force is estimated using Karush-Kuhn-Tucker (K-K-T) multipliers. Co-contraction is modelled as an incremental increase in the lower bounds on the allowable muscle forces in an optimization model formation. The K-K-T multipliers associated with each lower bound provide an estimate of the partial derivate of the optimal objective function value with respect to a change in the lower bound. A model whose objective function is spinal compression force is analyzed to estimate the effect of co-contraction on spinal compression force. While the effect depends on the specific muscle and task under consideration, the marginal effect of co-contraction on spinal compression force can be as high as 5.52 N additional spinal compression force for every additional N of muscle force. Paradoxically, the co-contraction may slightly decrease predicted spinal compression in special circumstances.
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Enhancing security of fingerprints through contextual biometric watermarking.
This paper presents a novel digital watermarking technique using face and demographic text data as multiple watermarks for verifying the chain of custody and protecting the integrity of a fingerprint image. The watermarks are embedded in selected texture regions of a fingerprint image using discrete wavelet transform. Experimental results show that modifications in these locations are visually imperceptible and maintain the minutiae details. The integrity of the fingerprint image is verified through the high matching scores obtained from an automatic fingerprint identification system. There is also a high degree of visual correlation between the embedded images, and the extracted images from the watermarked fingerprint. The degree of similarity is computed using pixel-based metrics and human visual system metrics. The results also show that the proposed watermarked fingerprint and the extracted images are resilient to common attacks such as compression, filtering, and noise.
Algorithms↗