Search

Contains fulltext : 71531.pdf (Publisher’s version ) (Closed access) BACKGROUND AND PURPOSE: Functional outcome in patients with minor head injury with neurocranial traumatic findings on CT is largely unknown. We hypothesized that certain CT findings may be predictive of poor functional outcome. Materials and METHODS: All patients from the CT in Head Injury Patients (CHIP) study with neurocranial traumatic CT findings were included. The CHIP study is a prospective, multicenter study of consecutive patients, > or =16 years of age, presenting within 24 hours of blunt head injury, with a Glasgow Coma Scale (GCS) score of 13-14 or a GCS score of 15 and a risk factor. Primary outcome was functional outcome according to the Glasgow Outcome Scale (GOS). Other outcome measures were the modified Rankin Scale (mRS), the Barthel Index (BI), and number and severity of postconcussive symptoms. The association between CT findings and outcome was assessed by using univariable and multivariable regression analysis. RESULTS: GOS was assessed in 237/312 patients (76%) at an average of 15 months after injury. There was full recovery in 150 patients (63%), moderate disability in 70 (30%), severe disability in 7 (3.0%), and death in 10 (4.2%). Outcome according to the mRS and BI was also favorable in most patients, but 82% of patients had postconcussive symptoms. Evidence of parenchymal damage was the only independent predictor of poor functional outcome (odds ratio = 1.89, P = .022). CONCLUSION: Patients with neurocranial complications after minor head injury generally make a good functional recovery, but postconcussive symptoms may persist. Evidence of parenchymal damage on CT was predictive of poor functional outcome.

Contains fulltext : 120568.pdf (Publisher’s version ) (Open Access) Human sound localization relies on binaural difference cues for sound-source azimuth and pinna-related spectral shape cues for sound elevation. Although the interaural timing and level difference cues are weighted to produce a percept of sound azimuth, much less is known about binaural mechanisms underlying elevation perception. This problem is particularly interesting for the frontal hemifield, where binaural inputs are of comparable strength. In this paper, localization experiments are described in which hearing for each ear was either normal, or spectrally disrupted by a mold fitted to the external ear. Head-fixed saccadic eye movements were used as a rapid and accurate indicator of perceived sound direction in azimuth and elevation. In the control condition (both ears free) azimuth and elevation components of saccadic responses were well described by a linear regression line for the entire measured range. For unilateral mold conditions, the azimuth response components did not differ from controls. The influence of the mold on elevation responses was largest on the ipsilateral side, and declined systematically with azimuth towards the side of the free ear. Near the midsagittal plane the elevation responses were clearly affected by the mold, suggesting a systematic binaural interaction in the neural computation of perceived elevation that straddles the midline. A quantitative comparison of responses from the unilateral mold, the bilateral mold and control condition provided evidence that the fusion process can be described by binaural weighted averaging. Two different conceptual schemes are discussed that could underlie the observed responses.

Item does not contain fulltext The directionally sensitive acoustics of the pinnae enable humans to perceive the up-down and front-back direction of sound. This mechanism complements another, independent mechanism that derives sound-source azimuth from interaural difference cues. The pinnae effectively add direction-dependent spectral notches and peaks to the incoming sound, and it has been shown that such features are used to code sound direction in the median plane. However, it is still unclear which of the pinna-induced features play a role in sound localization. The present study presents a method for the reconstruction of the spatially relevant features in the spectral domain. Broadband sounds with random spectral shapes were presented in rapid succession as subjects made saccadic eye movements toward the perceived stimulus locations. The analysis, which is based on Bayesian statistics, indicates that specific spectral features could be associated with perceived spatial locations. Spectral features that were determined by this psychophysical method resemble the main characteristics of the pinna transfer functions obtained from acoustic measurements in the ear canal. Despite current experimental limitations, the approach may prove useful in the study of perceptually relevant spectral cues underlying human sound localization.

This paper describes the effect of spectro-temporal factors on human sound localization performance in two dimensions (2D). Subjects responded with saccadic eye movements to acoustic stimuli presented in the frontal hemisphere. Both the horizontal (azimuth) and vertical (elevation) stimulus location were varied randomly. Three types of stimuli were used, having different spectro-temporal patterns, but identically shaped broadband averaged power spectra: noise bursts, frequency-modulated tones, and trains of short noise bursts. In all subjects, the elevation components of the saccadic responses varied systematically with the different temporal parameters, whereas the azimuth response components remained equally accurate for all stimulus conditions. The data show that the auditory system does not calculate a final elevation estimate from a long-term (order 100 ms) integration of sensory input. Instead, the results suggest that the auditory system may apply a “multiple-look” strategy in which the final estimate is calculated from consecutive short-term (order few ms) estimates. These findings are incorporated in a conceptual model that accounts for the data and proposes a scheme for the temporal processing of spectral sensory information into a dynamic estimate of sound elevation.

Detection of circulating tumor cells (CTCs) morphologically may be a promising new approach in clinical oncology. We tested the reliability of a cytomorphologic approach to identify CTCs: 808 blood samples from patients with benign and malignant diseases and healthy volunteers were examined using the isolation by size of epithelial tumor cell (ISET) method. Cells having nonhematologic features (so-called circulating nonhematologic cells [CNHCs]) were classified into 3 categories: CNHCs with malignant features, CNHCs with uncertain malignant features, and CNHCs with benign features. CNHCs were found in 11.1% and 48.9% of patients with nonmalignant and malignant pathologies, respectively (P.001). CNHCs with malignant features were observed in 5.3% and in 43.1% of patients with nonmalignant and malignant pathologies, respectively. Cytopathologic identification of CTCs using the ISET method represents a promising field for cytopathologists. The possibility of false-positive diagnosis stresses the need for using ancillary methods to improve this approach.

Contains fulltext : 53711.pdf (Publisher’s version ) (Closed access) OBJECTIVE: A history of loss of consciousness (LOC) or post-traumatic amnesia (PTA) is commonly considered a prerequisite for minor head injury (MHI), although neurocranial complications also occur when LOC/PTA are absent, particularly in the presence of other risk factors. The purpose of this study was to evaluate whether known risk factors for complications after MHI in the absence of LOC/PTA have the same predictive value as when LOC/PTA are present. METHODS: A prospective multicentre study was performed in four university hospitals between February 2002 and August 2004 of consecutive blunt head injury patients (> or = 16 years) presenting with a normal level of consciousness and a risk factor. Outcome measures were any neurocranial traumatic CT finding and neurosurgical intervention. Common odds ratios (OR) were estimated for each of the risk factors and tested for homogeneity. RESULTS: 2462 patients were included: 1708 with and 754 without LOC/PTA. Neurocranial traumatic findings on CT were present in 7.5% and were more common when LOC/PTA was present (8.7%). Neurosurgical intervention was required in 0.4%, irrespective of the presence of LOC/PTA. ORs were comparable across the two subgroups (p>0.05), except for clinical evidence of a skull fracture, with high ORs both when LOC/PTA was present (OR = 37, 95% CI 17 to 80) or absent (OR = 6.9, 95% CI 1.8 to 27). LOC and PTA had significant ORs of 1.9 (95% CI 1.0 to 2.7) and 1.7 (95% CI 1.3 to 2.3), respectively. CONCLUSION: Known risk factors have comparable ORs in MHI patients with or without LOC or PTA. MHI patients without LOC or PTA need to be explicitly considered in clinical guidelines.

Blocking artifacts may appear in block based digital image and video coding systems like JPEG and MPEG, especially when compression is done at a low bit-rate. The blocking artifacts can degrade the perceived image quality. In this paper, a method for reducing the blocking artifacts in the decoded image using adaptive filters is proposed. The selection of the proper filter is based on the local image pattern and/or the relative pixel position in the coding block. The results show a significant image quality improvement. To evaluate the methods, both Mean Square Error (MSE) scores and Block-edge Impairment Metric (BIM) are given for objective comparison. Screen shots are also shown to demonstrate the subjective quality.

We propose a new class of non-linear filters for image interpolation, content-adaptive neural filters using pixel classification. In the proposed method, the neural filter coefficients depend on the local structure of the image data, which can be classified into classes based on the luminance pattern in the filter aperture. The optimal coefficients of the neural filters are obtained for each class by supervised learning which employs the original high resolution and the down-scaled images as the training set. As the proposed filters are considered an extension of the content-adaptive linear filters, we perform the evaluation and analysis of the proposed filters versus the content-adaptive linear filters. The results suggest that the proposed algorithm demonstrates more robust estimation in image interpolation and gives an additional improvement in the interpolated image quality. Since the number of classes using the pixel classification increases exponentially with the aperture size we also introduce a method to reduce the number of the classes.

In a Standard Definition (SD) Television system, the Y:U:V video format 4:2:2 with chrominance sub-sampling is widely used. With the advent of High Definition (HD) television, the 4:4:4 format is required for high-performance TV. High-quality up-sampling methods have been developed to perform a resolution conversion from Standard Definition (SD) signal to HD signal. Although these algorithms have been designed for spatial scaling of luminance, they may be adapted and used to up-sample the low-resolution components U,V (4:2:2) to a high-resolution UV-colour format (4:4:4). In this paper, a content-adaptive up-scaling method for chrominance is proposed, with interpolation filters that adapt to the local structure of both luminance and chrominance data. Optimal filters were computed from a large video data set in different colour formats, such that original high-resolution data in a 4:4:4 format was reconstructed from low-resolution colour data, on the basis of the Least Mean Square (LMS) criterion. By combining edge information of both luminance and chrominance, the edge in the chrominance signal can be detected more accurately, thus exploiting the wider bandwidth of the luminance signal.

Item does not contain fulltext This paper describes the application of a small hearing aid that precisely fits into a subject's ear canal (complete-in-canal, or CIC). The bandwidth of the device is about 7 kHz. The system allows for selective manipulation of the different acoustic cues used for sound localization. The potential of the system is illustrated by robustly interchanging the input of the left and right ear, and consequently changing the sign of the binaural difference cues (both interaural phase and intensity) that are used for horizontal sound localization. As a result, left-right perception is reversed, while high-frequency pinna cues are sufficiently preserved to maintain up-down localization. As the hearing condition is well-defined, the auditory system could in principle remap these cues into a new representation of sound azimuth by relating the modified cues to veridical sound locations. The hearing aids were applied in four human subjects. Swapped binaural hearing was tested in two of the subjects. Swapped localization experiments for an extended period indicated stable performance of both subjects. Interestingly, an adaptive response to the reversed interaural cues was not observed. The current system may prove useful for psychophysical studies that concern the independent processing of sound localization cues, as well as in long-term developmental and plasticity studies with animals.

Because the inner ear is not organized spatially but tonotopically, sound localization relies on the neural processing of implicit acoustic cues. To determine a sound’s position, the brain must learn and calibrate these individual cues, using accurate spatial feedback from other sensorimotor systems. Experimental evidence for such a system has been demonstrated in barn owls, but not in humans. In this study, the existence of ongoing spatial calibration in the adult human auditory system is demonstrated. The spectral elevation cues of human subjects were disrupted by modifying their outer ears (pinnae) with molds. Although localization of sound elevation was dramatically degraded immediately after the modification, accurate performance was steadily reacquired. Interestingly, learning the new spectral cues did not interfere with the neural representation of the original cues, as subjects could localize sounds with both normal and modified pinnae.

The direction-dependent acoustic filtering of the external ear plays an important role in sound localization. It is believed to be essential for the detection of sound elevation, whereas sound azimuth follows from binaural difference cues in intensity and phase. Sound elevation is believed to be coded by prominent and characteristic features in the sound power spectrum at the sensory level, like peaks and valleys. However, it is still not known what the relative importance is of each of these features and how sound elevation can be calculated from them. This paper presents a localization model that enables extraction of the features that can be expected to be relevant in elevation detection. A feature was characterized as a spectral derivative of a certain order and scale, where a simple two-layer network was used to determine its importance in computing sound elevation.

Simple probabilistic neural models can be used to study the information processing occurring in the brain. Suitable models have to reproduce complex Interspike Histograms (ISHs) observed experimentally, but have to be simple enough to allow theoretical analysis. The simple probabilistic integrate and fire model we present in this paper can be used to identify the origin of peaks appearing in complex multimodal ISHs.