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Showing papers in "Biomedical sciences instrumentation in 2015"


Journal Article
TL;DR: The results suggest that at least in some situations the Liljestrand and Zander method may provide an adequate measure of CO when other methods are not available.
Abstract: Cardiac output (CO) is an important indicator of cardiovascular function. Several invasive and non-invasive methods have been developed and validated to assess CO in the clinical setting. These are often computationally complex or proprietarily-restricted, and thus, not feasible in ambulatory investigations and the laboratory research setting. Simple mathematical transforms have been proposed to estimate CO from pulse pressure (PP = mean systolic blood pressure (SBP) minus mean diastolic blood pressure (DBP)), and mean heart rate (HR). Recently we evaluated one such simple technique [CO=(PPxHR)x.002], and found moderate correlation between the CO estimate and Modelflow-derived CO. Here we aimed to evaluate a more sophisticated formula, proposed in 1940 by Liljestrand and Zander. CO was estimated (COEST) dividing PP by the sum of SBP and DBP and multiplying the product by HR. This index was correlated with the Modelflow (3 element Windkessel) -derived CO. Baseline beat-to-beat blood pressure data from 67 young (mean age = 19.94± 2.8), healthy men (n = 30) and women (n = 37) was available for analysis. Overall, the correlation of COEST and CO was moderate (r = .42, p <.0001) and stronger in men (r = .66, p < .0001) compared to women (r = .36, p < .05). These results suggest that at least in some situations the Liljestrand and Zander method may provide an adequate measure of CO when other methods are not available.

16 citations


Journal Article
TL;DR: The results of this study provided the literature with more insights regarding manipulation of ovarian cancer behavior through potent antioxidants such as TQ and EGCG in culture.
Abstract: Ovarian cancer is the leading cause of mortality among the gynecologic cancers and is the 5th most common cancer among women. Recent studies have indicated that antioxidant exposure may slow the progression in major neoplastic diseases. The objective of this study was to investigate the pathophysiological effects of Thymoquinone (TQ) and Epigallocatechin-3-gallate (EGCG) using the SK-OV-3 cell line as a model. A total of 72 wells were plated with (10^5) SK-OV-3 ovarian cancer cells according to standard lab protocols. Each group was subdivided into 4 groups of 6 wells each. Group 1 served as control and groups 2, 3, and 4 were treated with TQ (16 µM), EGCG (3 µg/ml), and TQ + EGCG, respectively. Biomarker and morphological evaluations were performed following standard lab techniques. The results of the study revealed: (1) there were no differences in protein levels for all time periods (p<0.05); (2) an increase in nitric oxide following the administration of EGCG alone and in combination with TQ compared with TQ alone or untreated control cells with the difference being approximately three-fold higher and this difference was statistically different (p<0.05) at 24, 48, 72 hours; (3) glutathione levels were not statistically different at all time periods (p<0.05); and (4) the MDA levels showed no damage to the SK-OV-3 ovarian cancer cells. The results of this study provided the literature with more insights regarding manipulation of ovarian cancer behavior through potent antioxidants such as TQ and EGCG in culture.

15 citations


Journal Article
TL;DR: The calculated and experimental muscle discomfort zone closely matched in 72% of subjects indicating that multifractal technique may be a good method for detecting onset of fatigue.
Abstract: Prolonged and repeated fatigue conditions can cause muscle damage and adversely impact coordination in dynamic contractions. Hence it is important to determine the onset of muscle fatigue (OMF) in clinical rehabilitation and sports medicine. The aim of this study is to propose a method for analyzing surface electromyography (sEMG) signals and identify OMF using multifractal detrending moving average algorithm (MFDMA). Signals are recorded from biceps brachii muscles of twenty two healthy volunteers while performing standard curl exercise. The first instance of muscle discomfort during curl exercise is considered as experimental OMF. Signals are pre-processed and divided into 1-second epoch for MFDMA analysis. Degree of multifractality (DOM) feature is calculated from multifractal spectrum. Further, the variance of DOM is computed and OMF is calculated from instances of high peaks. The analysis is carried out by dividing the entire duration into six equal zones for time axis normalization. High peaks are observed in zones where subjects reported muscle discomfort. First muscle discomfort occurred in third and forth zones for majority of subjects. The calculated and experimental muscle discomfort zone closely matched in 72% of subjects indicating that multifractal technique may be a good method for detecting onset of fatigue. The experimental data may have an element of subjectivity in identifying muscle discomfort. This work can also be useful to analyze progressive changes in muscle dynamics in neuromuscular condition and co-contraction activity.

12 citations


Journal Article
TL;DR: The results indicated that blast exposure causes acute changes in gene expression and protein levels of epigenetic markers which correlate with changes observed in AD pathology, which could provide novel targets for therapeutic interventions following BINT.
Abstract: Blast induced neurotrauma (BINT) leads to widespread aberrant gene expression and molecular changes resulting in cognitive impairment. Enzymes such as HDAC2, HDAC6, SIRT1, DNMT1, DNMT3a and DNMT3b control histone acetylation and DNA methylation which play a major role in regulation of the transcriptome. Changes in the expression of these enzymes have been implicated in the pathology of traumatic brain injury (TBI) and Alzheimer’s disease (AD). We hypothesize that blast exposure will lead to changes in the expression of these enzymes which play a key role in injury progression and pathology. This study looked to identify epigenome changes in the acute stages of BINT using an established rodent model. Real time polymerase chain reaction and Western blot analyses were used to assess gene expression and protein level changes compared to sham. No significant changes were seen 24 hours after blast exposure. However, several changes were observed at 72 hours following blast exposure. There was a significant increase in expression of HDAC2 and HDAC6 in the hippocampus which correlated with elevated HDAC2 protein levels. SIRT1, DNMT3a and DNMT3b levels were all reduced in the hippocampus. In the medial prefrontal cortex, DNMT1 and DNMT3b were significantly reduced. The results indicated that blast exposure causes acute changes in gene expression and protein levels of epigenetic markers which correlate with changes observed in AD pathology. These epigenomic changes could provide novel targets for therapeutic interventions following BINT.

12 citations


Journal Article
TL;DR: Though the region of interest of the signals examined in the current study did not contain extremely high frequency content, it is possible that live-fire testing may produce shock waves with higher frequency content.
Abstract: The human skull is a multi-layered composite system critical in protecting the brain during head impact. Head impact studies investigating skull injury thresholds have suggested that the skull and scalp thickness affect the risk of fracture. Therefore, accurately determining the dimensions of skull-scalp constituents is a necessary step in attributing the contribution to response, failure mechanisms and in developing high fidelity human models. However, prior methods to collect these data include physical measurements of biopsies and manual segmentation in X-ray images. These methods are invasive and impractical for clinical applications, or insufficient to characterize the regional variance in the skull-scalp constituents for a full mechanical strength characterization. The newly developed methods in this study describe an automated, regional, and objective-based measurement technique to characterize the average thickness and variance in skull and scalp constituents using quantitative computed tomography (QCT). The developed approach was successfully employed on 7 specimens at 5 anatomically defined locations. RESULTS report the thicknesses for each layer, with the layer of greatest variation being the trabecular bone (diploe) having a standard deviation of 35.6% of its mean thickness. These results will be used to define skull morphology for modeling relative impact injury risk that will be experimentally validated. Language: en

8 citations


Journal Article
TL;DR: Wearable technology provides a unique opportunity to track lifestyle choices, such as increasing physical activity, and has the potential to impact chronic disease management and prevention.
Abstract: Chronic diseases are a major health concern at the national and global level. According to the CDC, 86% of US health dollars go toward the treatment of chronic diseases. Many chronic diseases are manageable or preventable if individuals make appropriate lifestyle choices. Wearable technology – both consumer and medical – provides a unique opportunity to track lifestyle choices, such as increasing physical activity. It is estimated the market for consumer wearables will grow from $9.2 billion in 2014 to $30 billion by 2018. With such a potential market growth, it is important to understand the potential benefits and limitations of wearable technology to impact chronic disease management and prevention.

8 citations


Journal Article
TL;DR: The results indicate that, at least relative to balance performance, the tone-based sound stimulation the authors investigated is effective andherently safe, but that tone selection depends on the individual subject.
Abstract: Sound is known to affect the human brain, hence sound or music therapy is sometimes used to improve a subject's physicaland mental health. In this study, the effects sound stimulation has on balance were investigated by means of computerizeddynamic posturography tests performed with eyes closed on an unstable surface using a CAPS® system, exceeding theInternational Society for Posture and Gait Research (ISPGR) recommended metrological performance standards. Subjectswere tested without listening to any music (baseline), listening to “pure music”, and listening to the same music with differenttones embedded into it (one for each key). We found that different subjects react differently to different tones. Music alonedid not have a statistically significant effect on balance compared to the baseline, but the “best” tone significantly improvedbalance compared to the baseline or the “pure music” conditions. Furthermore, the “worst” tone reduced the balancecompared to “pure music”, but the reduction was not statistically significant relative to the baseline. The results thereforeindicate that, at least relative to balance performance, the tone-based sound stimulation we investigated is effective andinherently safe, but that tone selection depends on the individual subject.

7 citations


Journal Article
TL;DR: Two- and three-dimensional models of astrocytes were studied to better understand the mechanisms of BINT at the microscopic level and indicated that glial cells survived and became activated by 72 hours following exposure.
Abstract: When access to live-fire test facilities is limited, experimental studies of blast-related injuries necessitate the use of a shock tube or Advanced Blast Simulator (ABS) to mimic free-field blast overpressure. However, modeling blast overpressure in a laboratory setting potentially introduces experimental artifacts in measured responses. Due to the high sampling rates required to capture a blast overpressure event, proximity to alternating current (AC-powered electronics) and poorly strain-relieved or unshielded wires can result in artifacts in the recorded overpressure trace. Data in this study were collected for tests conducted on an empty ABS (Empty Tube) using high frequency pressure sensors specifically designed for blast loading rates (n=5). Additionally, intraocular overpressure data (IOP) were collected for porcine eyes potted inside synthetic orbits located inside the ABS using an unshielded miniature pressure sensor (n=3). All tests were conducted at a 30 psi static overpressure level. A 4th order phaseless low pass Butterworth software filter was applied to the data. Various cutoff frequencies were examined to determine if the raw shock wave parameters values could be preserved while eliminating noise and artifacts. A Fast Fourier Transform (FFT) was applied to each test to examine the frequency spectra of the raw and filtered signals. Shock wave parameters (time of arrival, peak overpressure, positive duration, and positive impulse) were quantified using a custom MATLAB® script. Lower cutoff frequencies attenuated the raw signal, effectively decreasing the peak overpressure and increasing the positive duration. Rise time was not preserved the filtered data. A CFC 6000 filter preserved the remaining shock wave parameters within ±2.5% of the average raw values for the Empty Tube test data. A CFC 7000 filter removed experimental high-frequency artifacts and preserved the remaining shock wave parameters within ±2.5% of the average raw values for test IOP test data. Though the region of interest of the signals examined in the current study did not contain extremely high frequency content, it is possible that live-fire testing may produce shock waves with higher frequency content. While post-processing filtering can remove experimental artifacts, special care should be taken to minimize or eliminate the possibility of recording these artifacts in the first place. Language: en

6 citations


Journal Article
TL;DR: It was concluded that slip training in VR environment could produce comparable results in fall intervention as well as improving reactive recovery in older adults.
Abstract: Slip training is gaining popularity as an innovative fall intervention approach. The objective of this study was to compare the efficacy of two different slip training modality (moveable platform and virtual reality) in reducing fall frequency and improving reactive recovery in older adults. Thirty-six healthy older adults were involved in a laboratory study, and were equally and randomly divided into the control group, the moveable platform training (MPT) group, and the virtual reality training (VRT) group. The MPT was achieved by inducing slips using a custom built sliding device consisting of a low friction, motorized moveable platform. The VRT was conducted by inducing visual perturbation in a head mounted display while subjects walked on a treadmill. All groups performed slip trials (kinematics, kinetics and EMG data were collected) on an actual slippery floor surface before and after a training session. The results indicated a significant reduction in fall frequency in both training groups. Between MPT and VRT groups, significant differences were also found in forward trunk rotations, peak knee angular velocity, ankle coactivity, and muscular activity in tibialis anterior. It was concluded that slip training in VR environment could produce comparable results in fall intervention.

6 citations


Journal Article
TL;DR: An attempt has been made to segment Corpus Callosum using edge based level set method, which seems to be clinically useful as callosal atrophy is significant in the diagnosis of AD.
Abstract: Alzheimer’s Disease (AD) is a common form of dementia that affects gray and white matter structures of brain. Manifestation of AD leads to cognitive deficits such as memory impairment problems, ability to think and difficulties in performing day to day activities. Although the etiology of this disease is unclear, imaging biomarkers are highly useful in the early diagnosis of AD. Magnetic resonance imaging is an indispensible non-invasive imaging modality that reflects both the geometry and pathology of the brain. Corpus Callosum (CC) is the largest white matter structure as well as the main inter-hemispheric fiber connection that undergoes regional alterations due to AD. Therefore, segmentation and feature extraction are predominantly essential to characterize the CC atrophy. In this work, an attempt has been made to segment CC using edge based level set method. Prior to segmentation, the images are pre-processed using Total Variation (TV) based diffusion filtering to enhance the edge information. Shape based geometric features are extracted from the segmented CC images to analyze the CC atrophy. Results show that the edge based level set method is able to segment CC in both the normal and AD images. TV based diffusion filtering has performed uniform region specific smoothing thereby preserving the texture and small scale details of the image. Consequently, the edge map of CC in both the normal and AD are apparently sharp and distinct with continuous boundaries. This facilitates the final contour to correctly segment CC from the nearby structures. The extracted geometric features such as area, perimeter and minor axis are found to have the percentage difference of 5.97%, 22.22% and 9.52% respectively in the demarcation of AD subjects. As callosal atrophy is significant in the diagnosis of AD, this study seems to be clinically useful.

6 citations


Journal Article
TL;DR: The present Injury Assessment Reference Curves and Values (IARC and IARV) may be used in future tests for advancing safety in military environments and these survival analysis processes and IARC andIARV data may also be usedin other applications.
Abstract: Traumatic brain injury (TBI) is a leading cause of disability and injury-related death, accounting for nearly one third of all injury-related deaths. To prevent and understand these types of injuries, finite element models can be employed. In this study, an anatomically accurate finite element model was developed from the International Consortium for Brain Mapping (ICBM) using a voxel-based mesh generation approach. The aim of this study was to compare relative brain displacement of the atlas-based brain model (ABM) to cadaveric data. In these experiments, neutral density targets (NDTs) were implanted in the brain and their relative motion with respect to the skull was recorded. The same boundary conditions were applied to ABM and the relative displacements of the nodes nearest to the physical location of each NDT were computed. Initial simulation and validation show good agreement with experimental data. The data obtained in this study and further development of this model will help us understand the biomechanics of head injury as well as provide a tool to predict and prevent brain injury. Language: en

Journal Article
TL;DR: Although the study is of a limited sample size, it suggests the need for further testing to develop standards that provide similar levels of safety for obliquely mounted seats as forward/aft facing seats in aircraft.
Abstract: Demineralized bone matrix protein (DBM) was considered highly effective in stimulating bone healing. The objective of the study was to explore the use of tricalcium phosphate (TCP) delivery system to continuously deliver DBM in an osteoporotic condition and to evaluate changes in bone density and preservation of the spine. Ovariectomized Sprague Dawley rats were divided into three equal groups (n=16 per group). Animals in group I served as control, animals in groups II and III were surgically implanted with either empty (SHAM) or DBM filled TCP implants adjacent to L4/L5. Eight animals from each group were euthanized at 2 and 8 weeks post implantation. Femurs were evaluated for changes in density, and the lumbar spine was evaluated for changes in the endplate. RESULTS of this study revealed (1) TCP implants were capable of delivering DBM for long duration, (2) use of sustained delivery of DBM did not induce untoward effects in the vital organs or in the uterus, fallopian tubes, or vaginal tissues, (3) DBM had no effect on chondrocyte differentiation in the spine, and (4) DBM did not increase bone density in osteoporotic female rats. Language: en

Journal Article
TL;DR: It is observed that the statistical analysis performed over the extracted features show distinct variation between the age groups, so the methodology proposed in this work could be useful for the analysis of frailty especially for the subjects above 60 years.
Abstract: Surface electromyography (sEMG) signal is the electrical manifestation of neuromuscular activities. It is an intricate signal that depends on the anatomical and physiological properties of the contracting muscles beneath the skin. In this work, a single channel surface EMG amplifier is designed to acquire the signals non-invasively from the skin by using bio-potential electrodes for three different hand movements. Subjects of age group 1 (18-30 years) and group 2 (60-78 years) are considered for this analysis. The recorded signals are pre-processed using Empirical Mode Decomposition (EMD) method to remove unwanted noises. Various error measures and performance index are calculated from the pre-processed sEMG signals to compare the performance of EMD with conventional digital filters. Relevant time and frequency domain features are extracted from the pre-processed signals. It is observed that the statistical analysis performed over the extracted features show distinct variation between the age groups. Thus the methodology proposed in this work could be useful for the analysis of frailty especially for the subjects above 60 years.

Journal Article
TL;DR: An attempt has been made to differentiate the sEMG signals under muscle non-fatigue and fatigue conditions using Zhao-Atlas-Marks (ZAM) based time frequency distribution, and the results show that IMDF and IMNF are distinct for muscleNonFatigue and Fatigue conditions.
Abstract: Muscle fatigue is a neuromuscular condition where muscles fail to generate the required force. It occurs in normal as well as abnormal subjects. The analysis of muscle fatigue plays a significant role in the field of clinical studies, myo-electric control, ergonomics and sports biomechanics. In this work, an attempt has been made to differentiate the sEMG signals under muscle non-fatigue and fatigue conditions using Zhao-Atlas-Marks (ZAM) based time frequency distribution. For this purpose, sEMG signals are recorded from fifty healthy volunteers during isometric contractions under well defined protocol. The acquired signals are preprocessed and subjected to ZAM based time-frequency analysis. The time-frequency based features such as instantaneous median frequency (IMDF) and instantaneous mean frequency (IMNF) are extracted from the time-frequency spectrum. The results show that IMDF and IMNF are distinct for muscle non-fatigue and fatigue conditions. Further, more number of frequency components are observed in the time-frequency spectrum of signals recorded in nonfatigue conditions. The t-test performed on these features has shown significant difference (p<0.01) in between non-fatigue and fatigue conditions. Thus the study seems to be useful for the analysis of various neuromuscular conditions.

Journal Article
TL;DR: Results show EGCG induced changes in cellular morphology which are characteristic of apoptosis, and additional studies are needed to determine the effects of E GCG on AMPK and ATM pathways that are responsible in normal cellular apoptotic processes.
Abstract: There is less than a thirty percent survival rate for patients with a localized pancreatic tumor, and less than a ten percent survival rate for patients with metastases. Patients with pancreatic cancer often have altered glucose metabolism and are prescribed metformin which has been shown to reduce cancer cell proliferation. Metformin administered at doses ranging between 10-20 mM has been reported in the literature to induce AMPK signaling pathways which increase cellular apoptosis. Epigallacto-catechan (EGCG) is a polyphenolic antioxidant that has also been shown to increase the AMPK pathway that increases cellular apoptosis. The objective of this study was to investigate the effectiveness of EGCG with a clinical dose of metformin (10µM) in reducing the survival of a pancreatic like cell line in culture. PANC-1 cells were plated onto three 24 well plates at a density of 1 x 106 cells per well. The experimental design consisted of four equal groups: Group 1 served as the control and groups 2-4 were treated with metformin, (EGCG) or metformin and EGCG, respectively. Biochemical and morphological evaluations were conducted following standard lab protocols. Results of this study show 10µM of metformin was unable to alter cell growth or proliferation over a 72 hour period, while 50µM of EGCG alone or in combination with metformin were capable of reducing cell density and cellular protein levels at 48 and 72 hours following treatment. The results show EGCG induced changes in cellular morphology which are characteristic of apoptosis. Overall, additional studies are needed to determine the effects of EGCG on AMPK and ATM pathways that are responsible in normal cellular apoptotic processes.

Journal Article
TL;DR: Shorter step length, wider step width, faster step duration, and higher muscle co-contraction at the ankle joint were observed strategies for fall recovery and regaining body stability.
Abstract: Prolonged exposure to vibrational working conditions can cause neck, back, and shoulder pain. Mechanical degradation of soft tissues resulting from this type of fatigue was experimentally shown to contribute to endplate and compression fractures. However, effects of repetitive subfailure loading on intervertebral disc (IVD) behavior have not been well defined. This manuscript describes a methodology to experimentally characterize changes in cervical spine IVD material properties under fatigue. Bone-disc-bone spinal units with intact ligaments obtained from human cervical spines were obtained and a lack of bony or soft tissue degeneration was confirmed using X-ray and MRI scans. Cranial and caudal specimen extents were fixed in PMMA to facilitate attachment to testing devices. Baseline response was quantified using flexion/extension pure moment protocols. Specimens were immersed in a 34-deg-C saline bath and allowed to acclimate for one hour. A stress-relaxation test was then performed and viscoelasticity quantified using a quasi linear viscoelastic (QLV) material model. Fatigue testing was performed for up to 50,000 cycles with intermittent viscoelasticity, pure moment testing, and imaging scans performed to quantify cycle-dependent changes in disc properties. Preliminary results demonstrated progressive changes in viscoelasticity and bending response of cervical spine segments with increasing number of load cycles. This procedure will be used to quantify degradation of the IVD under repetitive compressive loads, focusing on effects of loading magnitude and frequency. Language: en

Journal Article
TL;DR: Using a direct IR device, it is investigated if it is possible to changesaccades using a novel brain and vestibular rehabilitation therapy in subjects suffering a variety of neurological dysfunctions and showed that this type of subject's specific therapy can improve with statistical significance the parameters of interest.
Abstract: Saccadic eye movements offer several insights into the functional status of many areas of the central nervous system. As suchtheir observation is an important component of any neurological assessment. Unfortunately, these types of eye movementsare very fast and therefore cannot be evaluated in detail without high speed instrumentation. Direct infrared (IR) technologyallows to easily quantify standard saccades parameters such as latency, peak and mean velocity, and Q factor, as well as torecord the actual shape of the movement and its velocity. Using a direct IR device, we investigated if it is possible to changesaccades using a novel brain and vestibular rehabilitation therapy in subjects suffering a variety of neurological dysfunctions.Pre-post therapy comparison of saccade parameters showed that this type of subject's specific therapy can improve withstatistical significance the parameters of interest. However, the effects were not limited to the parameters of interest:subject-specific brain and vestibular rehabilitation therapy can improve the other parameters as well, although thisimprovement was not always statistically significant. Furthermore, we found that for the infrequent cases where thesubject-specific brain and vestibular rehabilitation therapy produced a deterioration of the other parameters, it was notstatistically significant.

Journal Article
TL;DR: It appears that the segmentation based fractal texture features and SVM could help to build a robust automated diagnosis tool for auto-immune diseases.
Abstract: Observing and classifying the indirect immunofluorescence patterns on HEp-2 cells can help in detecting Anti-Nuclear-Antibodies. A computer algorithm to perform this function can lead to a more standardized, faster and accurate diagnosis of auto-immune diseases such as systemic lupus erythematosus, sjogren’s syndrome, and rheumatoid arthritis. In this paper, HEp-2 staining patterns are classified using segmentation based fractal texture features. The images used for this experimentation are obtained from a publicly available database. The features extracted from a cell image is used to classify it into homogenous, fine speckled, coarse speckled, centromere and nucleolus. The cell images are segmented using the ground truth mask provided in the database. Adaptive histogram equalization is applied to the segmented images for contrast enhancement. Three features namely mean intensity, area and Hausdorff fractal dimension of the border are extracted for 8 different Otsu threshold levels. Finally, the 24 features thus extracted are fed to a support vector machine with Gaussian radial basis function kernel. It is observed that the overall accuracy of classification is 65.17%. The accuracy is greatly dependent on scaling and distribution of the features given to SVM. It appears that the segmentation based fractal texture features and SVM could help to build a robust automated diagnosis tool for auto-immune diseases.

Journal Article
TL;DR: A novel approach to assess the severity of the dysarthria using state-specific vector (SSV) of phone-cluster adaptive training (phone-CAT) acoustic modeling technique is proposed, which correlates with the standard Frenchay dysarthric assessment scores by 74 % on Nemours database and with the intelligibility scores by 82 % on universal access Dysarthric speech database.
Abstract: In this paper, a novel approach to assess the severity of the dysarthria using state-specific vector (SSV) of phone-cluster adaptive training (phone-CAT) acoustic modeling technique is proposed. The dominant component of the SSV represents the actual pronunciations of a speaker. Comparing the dominant component for unimpaired and each dysarthric speaker, a phone confusion matrix is formed. The diagonal elements of the matrix capture the number of correct pronunciations for each dysarthric speaker. As the degree of impairment increases, the number of phones correctly pronounced by the speaker decreases. Thus the trace of the confusion matrix can be used as objective cue to assess di?erent severity levels of dysarthria based on a threshold rule. Our proposed objective measure correlates with the standard Frenchay dysarthric assessment scores by 74 % on Nemours database. The measure also correlates with the intelligibility scores by 82 % on universal access dysarthric speech database.

Journal Article
TL;DR: An attempt has been made to analyze the complexity of sEMG signals associated with fatigue conditions using Multiscale Approximate Entropy (MSApEn) technique and it is found that the signals are complex in both fatigue and nonfatigue conditions.
Abstract: Muscle fatigue is a neuromuscular condition which causes a decline in muscle performance. Surface electromyography (sEMG) signals are widely used to evaluate muscle fatigue and these signals are highly complex in nature. To address this, advanced signal processing techniques are necessary. In this work, an attempt has been made to analyze the complexity of sEMG signals associated with fatigue conditions using Multiscale Approximate Entropy (MSApEn) technique. Signals are recorded from biceps brachii muscles of fifty healthy subjects while performing curl exercise and it is divided into six equal segments to avoid variability in endurance time. The first and last segments are considered as nonfatigue and fatigue conditions respectively. The signals are preprocessed and MSApEn is evaluated. Further, four features namely median (MED), variance (VAR), high scale sum (HSS) and low scale sum (LSS) are extracted from each segment. The results indicate a distinct variation in the MSApEn values. It is found that the signals are complex in both fatigue and nonfatigue conditions. In addition, features namely the MED, HSS and LSS are found to be low in fatigue case. The t-test performed on these features shows high statistical significance (p-value<0.005). It appears that this method can be used to analyze the complexity of sEMG signals in varied clinical conditions.

Journal Article
TL;DR: Twenty years ago the author unveiled his inexpensive complex hand model, which reproduced every motion of the human hand and evolved into an innovative robot-AI within two decades.
Abstract: Twenty years ago the author unveiled his inexpensive complex hand model, which reproduced every motion of the human hand. A control system programmed in the Forth language operated its actuators and sensors. Follow-on papers for this popular project were next presented in Texas, Canada and Germany. From this hand grew the author’s meter-tall robot (nicknamed ANNIE: Android With Neural Networks, Intellect and Emotions). It received machine vision, facial expressiveness, speech synthesis and speech recognition; a simian version also received a dexterous ape foot. New artificial intelligence features included op-amp neurons for OCR and simulated emotions, hormone emulation, endocannabinoid receptors, fear-trust-love mechanisms, a Grandmother Cell recognizer and artificial consciousness. Simulated illnesses included narcotic addiction, autism, PTSD, fibromyalgia and Alzheimer’s disease. The author gave 13 robotics-AI presentations at NASA in Houston since 2006. A meter-tall simian robot was proposed with gripping hand-feet for use with space vehicles and to explore distant planets and moons. Also proposed were: intelligent motorized exoskeletons for astronaut force multiplication; a cognitive prosthesis to detect and alleviate decreased crew mental performance; and a gynoid robot medic to tend astronauts in deep space missions. What began as a complex hand model evolved into an innovative robot-AI within two decades.

Journal Article
TL;DR: Results of offline crossvalidation show that eye tracking can make target predictions earlier and more accurately than arm kinematics, especially when possible targets are close together, and combining eye tracking with contextual information further improves prediction accuracy.
Abstract: Rehabilitation robots physically support patients during exercise, but their assistive strategies often constrain patients by forcing them to execute predefined motions. To allow more freedom during rehabilitation, the robot should be able to predict what motion the patient wants to perform, then intelligently support the motion. As a first step, this paper presents an algorithm that predicts targets of reaching motions made with an arm rehabilitation exoskeleton. Different sensing modalities are compared with regard to their predictive abilities: arm kinematics, eye tracking, contextual information, and combinations of these modalities. Supervised machine learning is used to make predictions at different points of time during the motion. Results of offline crossvalidation using 12 healthy subjects show that eye tracking can make target predictions earlier and more accurately than arm kinematics, especially when possible targets are close together. Combining eye tracking with contextual information further improves prediction accuracy. The foreseen next step is to use our predictions to guide the rehabilitation robot, and then test the algorithm in real-time with stroke patients.

Journal Article
TL;DR: The results show that the DRLSE based level set method is able to extract the ventricle edges with less discontinuity and the MF- area increases with severity, which could be used for the study of discrimination and progression of the Alzheimer's disease like disorders.
Abstract: In this work, the ventricles in MR brain images are segmented using edge based modified Distance Regularized Level Set Evolution (DRLSE) method and the structural changes in the disease is further analysed using Minkowski functionals (MFs). Twenty normal and abnormal T1-weighted coronal mid slice MR image are considered for the analysis. The MR brain image is pre-processed using contrast enhancement method. The edge based modified DRLSE with a new penalty term is used to segment the ventricles from the enhanced images. The results of the level set method are compared with geodesic active contour method. The segmentation results are validated using ZSI (Zijdenbos Similarity Index) and F-score. The Minkowski functionals such as MF-area, MF-perimeter and MF-Euler number are calculated from the extracted ventricle region. The longitudinal analysis of ventricles is performed using these features. The results show that the DRLSE based level set method is able to extract the ventricle edges with less discontinuity. The F-score and ZSI is high for DRLSE (0.83 and 0.84) compared to geodesic method (0.79 and 0.80). The MF-area is able to discriminate the controls and the AD subjects with high statistical significance (p < 0.001). This analysis also shows that the MF- area increases with severity. These results could be used for the study of discrimination and progression of the Alzheimer's disease like disorders.

Journal Article
TL;DR: It appears that the methodology adopted here is useful in accurate segmentation and differentiation of normal and carcinoma breast tissues for automated diagnosis of breast abnormalities.
Abstract: Breast thermography plays a major role in early detection of breast cancer in which the thermal variations are associated with precancerous state of breast. The distribution of asymmetrical thermal patterns indicates the pathological condition in breast thermal images. In this work, asymmetry analysis of breast thermal images is carried out using level set segmentation and Zernike moments. The breast tissues are subjected to Tukey’s biweight robust anisotropic diffusion filtering (TBRAD) for the generation of edge map. Reaction diffusion level set method is employed for segmentation in which TBRAD edge map is used as stopping criterion during the level set evolution. Zernike moments are extracted from the segmented breast tissues to perform asymmetry analysis. Results show that the TBRAD filter is able to enhance the edges near infra mammary folds and lower breast boundaries effectively. It is observed that segmented breast tissues are found to be continuous and has sharper boundary. This method yields high degree of correlation (98%) between the segmented output and the ground truth images. Among the extracted Zernike features, higher order moments are found to be significant in demarcating normal and carcinoma breast tissues by 9%. It appears that, the methodology adopted here is useful in accurate segmentation and differentiation of normal and carcinoma breast tissues for automated diagnosis of breast abnormalities.

Journal Article
TL;DR: It is now known that primary neurogenic areas within the Central Nervous System (CNS) are located within the lateral ventricle and hippocampus and that ependymal cells are capable of migrating into the hypothalamus and undergo proliferation.
Abstract: Ependymal Cells are a type of Glial Cell lining the ventricles and central canal of the spinal cord. Their primary function is to secrete and circulate cerebrospinal fluid (CSF). Neural stem cells (NSC) exist within the ependymal lining that are capable of neurogenesis. Historically it was thought that neurogenesis only occurred prenatally and that adult ependymal cells are incapable of regeneration. It is now known that primary neurogenic areas within the Central Nervous System (CNS) are located within the lateral ventricle and hippocampus. Recent studies have demonstrated that ependymal cells lining the central cord canal possess dormant neural stem cells capable of differentiation following Spinal Cord Injury (SCI). Recent research has focused on strategies to modulate cellular proliferation and differentiation in the spinal cord. In SCI these cells have the propensity to migrate to the site of damage and differentiate into astrocytes and oligodendrocytes. Ependymal cells are also capable of migrating into the hypothalamus and undergo proliferation. Neurological insult such as SCI leads the oxidative stress response, inflammation and subsequent activation of ependymal cells into astrocytes that are the body’s way to regenerate and heal. The presence or absence of astrocytes, neuronal growth factors, non-neuronal growth factors, microtubule and microtubule activating proteins are factors which promote cell survival and terminal differentiation of neurons.

Journal Article
TL;DR: The proposed SLAD fuses two sources of data in realtime using a probabilistic likelihood framework, which allows activity data to refine localization, and vice-versa, and produces 97% localization accuracy and 85% activity classification.
Abstract: Shifting demographics in the U.S. has created an urgent need to reform the policies, practices, and technology associated with delivering healthcare to geriatric populations. Automated monitoring systems can improve the quality of life while reducing healthcare costs for individuals aging in place. For these systems to be successful, both activity detection and localization are important, but most existing research focuses on only one of these technologies and systems that do collect both data treat these data sources separately. Here, we present SLAD {Simultaneous Localization and Activity Detection a novel framework for simultaneously processing data collected from localization and activity classification systems. Using a hidden Markov model and machine learning techniques, SLAD fuses these two sources of data in realtime using a probabilistic likelihood framework, which allows activity data to refine localization, and vice-versa. To evaluate the system, a wireless sensor network was deployed to collect RSSI data and IMU data concurrently from a wrist-worn watch; the RSSI data was processed using a radial basis function neural network localization algorithm, and the resulting position likelihoods were combined with the likelihoods from an IMU acitivty classification algorithm. In an experiment conducted in an indoor office environment, the proposed method produces 97% localization accuracy and 85% activity classification.

Journal Article
TL;DR: Estimation of ocular aberrations showed there was no statistical significance between natural pupil and rescaled pupil diameter and the pupil rescaling technique was validated by using COAS (Complete Ophthalmic Analysis System)Shack Hartmann Aberrometer.
Abstract: In any optical system, optical aberrations of the imaging system affect the image quality. The human eye is also like an optical system which has optical aberrations influencing the quality of the retinal image. When pupil size exceeds 3 mm, ocular aberrations increase and play a major role on retinal image degradation. Pupil diameter is made constant in commercially available aberrometers by mathematically rescaling it. The aim of this study is to validate the pupil rescaling technique by using COAS (Complete Ophthalmic Analysis System)Shack Hartmann Aberrometer. Five subjects were recruited for this study. The measurements were taken over a moderately large pupil of 5mm in normal room illumination to allow for natural pupil dilation. The analyses diameter is fixed at 5 mm in COAS which means it rescales the aberration data to 5 mm if the pupil diameter recorded was more than 5 mm at the time of measurement. Ocular aberrations for natural and rescaled pupil sizes were analyzed. Estimation of ocular aberrations showed there was no statistical significance between natural pupil and rescaled pupil diameter.

Journal Article
TL;DR: Results suggest that HPCs are sensitive to low-level hydrostatic pressure associated with chronic liver disease and further experiments include analyzing cellular proliferation, morphology, and differentiation effects associated with pressure exposure.
Abstract: Hepatic progenitor cells (HPCs) have the potential to regenerate healthy tissue in the setting of chronic liver disease. The goal of this study was to characterize the mechanosensitivity of HPCs to sustained hydrostatic pressure (20 mmHg) similar to that observed in liver cirrhosis. Bipotential Murine Oval Liver (BMOL) cells, an HPC-like cell line, were cultured in a hydrostatic pressure controlled chamber at 37°C and 5% CO2 for 4 days (to 90% confluency) or 12 days (superconfluency). Controls were run for each time point in a standard incubator without pressure. Nuclei were stained with DAPI and cells were viewed under a Zeiss 710 laser scanning confocal microscope with 40x objective. Nuclei were measured with Image J software (170 to 398 distinct cell nucleus area measurements per group). Two-way ANOVA was used to examine the influence of pressure and confluency on nuclear size. Cells exposed to pressure (mean nuclear area 126.7µm2, S.D. 56.9) had significantly larger nuclei than control cells (mean nuclear area 102.3µm2, S.D. 84.1), p<.001. The pressure*confluency interaction was also significant (p<.05). Results suggest that HPCs are sensitive to low-level hydrostatic pressure associated with chronic liver disease. Further experiments include analyzing cellular proliferation, morphology, and differentiation effects associated with pressure exposure.

Journal Article
TL;DR: A method was developed to morph the Global Human Body Models Consortium 50th percentile male skull model to age and gender specific geometries based on the full thickness regressions using a Thin Plate Spline algorithm, which can be used to create gender and age-specific FE models of the skull.
Abstract: The aim of this study was to develop an active gait perturbation system and to evaluate its efficacy in evaluating fall recovery and gait adaptation. We hypothesized that a translating perturbation during the single stance phase would alter gait adaptations, in terms of gait parameters and muscle co-contractions, during recovery to maintain dynamic stability for continued walking. A customized miniature treadmill, built on a large force plate and embedded perpendicular to the walkway, was used to translate the loaded stance foot medially and laterally to interrupt swing foot trajectory. The perturbation was activated when the stepping foot was placed entirely on the belt to ensure the foot would remain on the belt when translated. The translating floor surface was applied to 10 young, healthy adult subjects (5 males, 5 females; aged Language: en

Journal Article
TL;DR: Simulation results show that the positions as well as the size of the inhomogeneity play a major role in the creation of reentrant waves while the shape of the inhalation does not have a significant effect.
Abstract: Arrhythmia generating conditions like ventricular hypertrophy, myocardial infarction or ischemia modify the intercellular coupling by modifying the conductance of gap junctions in the normal electric propagation pathway of the heart. A discrete ventricular cell network of 100x100 cells interconnected using resistive gap junctions is simulated to study the effect of size, shape and position of inhomogeneity as well as the value of gap junction conductance of inhomogeneity on the occurrence of reentrant arrhythmia. In addition to lowering the conduction, a unidirectional block is also created using exactly timed stimulation inputs thus setting the ideal conditions for a reentrant activation to arise from the zone of varied gap junction conductance. The shape and endurance of generated reentrant waves is analyzed. The electrical activity of each cell is simulated using the Ten Tusscher –Panfilov 2006 model. Simulation results show that the positions as well as the size of the inhomogeneity play a major role in the creation of reentrant waves while the shape of the inhomogeneity does not have a significant effect. Also, reentrant waves occur at a certain level of decoupling. Too much or too little decoupling also doesn’t induce reentrant waves. The amplitude and duration of action potential is heavily dependent on the gap junction conductance.