217 research outputs found
Quality Control of Motor Unit Number Index (MUNIX) Measurements in 6 Muscles in a Single-Subject “Round-Robin” Setup
Background
Motor Unit Number Index (MUNIX) is a neurophysiological measure that provides an index
of the number of lower motor neurons in a muscle. Its performance across centres in healthy
subjects and patients with Amyotrophic Lateral Sclerosis (ALS) has been established, but
inter-rater variability between multiple raters in one single subject has not been
investigated.
Objective
To assess reliability in a set of 6 muscles in a single subject among 12 examiners (6 experienced
with MUNIX, 6 less experienced) and to determine variables associated with variability
of measurements.
Methods
Twelve raters applied MUNIX in six different muscles (abductor pollicis brevis (APB),
abductor digiti minimi (ADM), biceps brachii (BB), tibialis anterior (TA), extensor dig. brevis
(EDB), abductor hallucis (AH)) twice in one single volunteer on consecutive days. All raters
visited at least one training course prior to measurements. Intra- and inter-rater variability as
determined by the coefficient of variation (COV) between different raters and their levels of
experience with MUNIX were compared.
Results
Mean intra-rater COV of MUNIX was 14.0% (±6.4) ranging from 5.8 (APB) to 30.3% (EDB).
Mean inter-rater COV was 18.1 (±5.4) ranging from 8.0 (BB) to 31.7 (AH). No significant differences
of variability between experienced and less experienced raters were detected.
Conclusion
We provide evidence that quality control for neurophysiological methods can be performed
with similar standards as in laboratory medicine. Intra- and inter-rater variability of MUNIX is
muscle-dependent and mainly below 20%. Experienced neurophysiologists can easily
adopt MUNIX and adequate teaching ensures reliable utilization of this method
Energetics and atomic mechanisms of dislocation nucleation in strained epitaxial layers
We study numerically the energetics and atomic mechanisms of misfit
dislocation nucleation and stress relaxation in a two-dimensional atomistic
model of strained epitaxial layers on a substrate with lattice misfit.
Relaxation processes from coherent to incoherent states for different
transition paths are studied using interatomic potentials of Lennard-Jones type
and a systematic saddle point and transition path search method. The method is
based on a combination of repulsive potential minimization and the Nudged
Elastic Band method. For a final state with a single misfit dislocation, the
minimum energy path and the corresponding activation barrier are obtained for
different misfits and interatomic potentials. We find that the energy barrier
decreases strongly with misfit. In contrast to continuous elastic theory, a
strong tensile-compressive asymmetry is observed. This asymmetry can be
understood as manifestation of asymmetry between repulsive and attractive
branches of pair potential and it is found to depend sensitively on the form of
the potential.Comment: 11 pages, 9 figures, to appear in Phys. Rev.
Comparative Analytical Study of Ashuddha Bhallataka and Shuddha Bhallataka
Introduction: Bhallataka (Semecarpus Anacardium Linn.) is reported under Upavisha Dravya in classical Ayurvedic pharmacopeias. It is observed that Shodhana (purification procedures) of the fruits should be carried out before its internal administration. There are different Shodhana methods mentioned in Ayurveda. In this study brick powder was used as media. Objective: To evaluate the impact of Shodhana on Ashuddha Bhallataka and to compare the physico analytical parameters of Ashuddha Bhallataka and Shuddha Bhallataka. Materials & Methods: Ashuddha Bhallataka was taken. Cap was removed and they dumped in Pottali with brick powder. Pottali was tied. Then they were rubbed intermittent with changing brick powder till the oily content secretion from them stopped. Then they are washed with leuk warm water and dried. Discussion: Ashuddha Bhallataka containes oil in it which is removed after Shodhana process. so that foreign matter, loss on drying was less in Shuddha Bhallataka and due to Shodhana process with brick powder total ash, acid insoluble ash, was more than that of Ashuddha Bhallataka
A New Approach of Clustering Feedback Sessions for Inferring User Search Goals
Internet information is growing every day exponentially. In order to find out the exact required information from this web search engines has become absolutely necessary tool for the web users. It has also become more difficult to provide user the required information. When Different users provide an ambiguous query to a search engine, they might be having different search goals. Therefore, it is required to find and analyze user search goals to improve the performance of a search engine and user experience. By representing the results in cluster we find out different user search goals for a query. It has advantages in improving search engine relevance and user experience. It extends the delivery and quality of internet information services to the end user. It also improves performance of Web server system. Query classification, search result reorganization and session boundary detection are the approaches attempt to find out user search goals. But the mentioned approaches has many limitations. A new approach has been implemented that overcomes the limitations and analyze, discover user search goals using feedback sessions. This approach first takes the user search query. For each single result of the search query pseudo-documents are generated. Using K-means++ clustering algorithm, these pseudo-documents are clustered. Each cluster can be considered as one user search goal. Finally in restructured result is given to the user where each URL is categorized into a cluster centered by the inferred search goals. Then depending upon user click through, results are restructured and represented to the user in order to satisfy the information need.
DOI: 10.17762/ijritcc2321-8169.15071
Survey on the Use of Feedback Sessions for Inferring User Search Goals
Largest source of web traffic are search engines. Search engines are being used by different kind of users for different purpose. When users are searching something they have a different search goal in mind. Thus the queries are mostly ambiguous one. In order to improve search engine relevance and thus user experience inference and analysis of user search is required. To get the best results it is needful to capture different user search goals. This paper first talks about the different ways of inferring user search goals. Then insights of new approach has been discussed. A new algorithm firstly specifies a framework to analyze user search goals by clustering feedback sessions. There should be a proper way to represent these feedback sessions. In the second step of this algorithm pseudo-documents are prepared to represent feedback sessions. With this original results are restructured. This in turn is used to select optimal user search goals
Fuzzy min-max neural networks for categorical data: application to missing data imputation
The fuzzy min–max neural network classifier is a supervised learning method. This classifier takes the hybrid neural networks and fuzzy systems approach. All input variables in the network are required to correspond to continuously valued variables, and this can be a significant constraint in many real-world situations where there are not only quantitative but also categorical data. The usual way of dealing with this type of variables is to replace the categorical by numerical values and treat them as if they were continuously valued. But this method, implicitly defines a possibly unsuitable metric for the categories. A number of different procedures have been proposed to tackle the problem. In this article, we present a new method. The procedure extends the fuzzy min–max neural network input to categorical variables by introducing new fuzzy sets, a new operation, and a new architecture. This provides for greater flexibility and wider application. The proposed method is then applied to missing data imputation in voting intention polls. The micro data—the set of the respondents’ individual answers to the questions—of this type of poll are especially suited for evaluating the method since they include a large number of numerical and categorical attributes
D-4F, an apoA-1 mimetic, decreases airway hyperresponsiveness, inflammation, and oxidative stress in a murine model of asthma
Asthma is characterized by oxidative stress and inflammation of the airways. Although proinflammatory lipids are involved in asthma, therapies targeting them remain lacking. Ac-DWFKAFYDKVAEKFKEAFNH2 (4F) is an apolipoprotein (apo)A-I mimetic that has been shown to preferentially bind oxidized lipids and improve HDL function. The objective of the present study was to determine the effects of 4F on oxidative stress, inflammation, and airway resistance in an established murine model of asthma. We show here that ovalbumin (OVA) -sensitization increased airway hyperresponsiveness, eosinophil recruitment, and collagen deposition in lungs of C57BL/6J mice by a mechanism that could be reduced by 4F. OVA sensitization induced marked increases in transforming growth factor (TGF)β-1, fibroblast specific protein (FSP)-1, anti-T15 autoantibody staining, and modest increases in 4-hydroxynonenal (4-HNE) Michael\u27s adducts in lungs of OVA-sensitized mice. 4F decreased TGFβ-1, FSP-1, anti-T15 autoantibody, and 4-HNE adducts in the lungs of the OVA-sensitized mice. Eosinophil peroxidase (EPO) activity in bronchial alveolar lavage fluid (BALF), peripheral eosinophil counts, total IgE, and proinflammatory HDL (p-HDL) were all increased in OVA-sensitized mice. 4F decreased BALF EPO activity, eosinophil counts, total IgE, and p-HDL in these mice. These data indicate that 4F reduces pulmonary inflammation and airway resistance in an experimental murine model of asthma by decreasing oxidative stress
Head-down tilt bed rest with or without artificial gravity is not associated with motor unit remodeling
© 2020, The Author(s). Purpose: The objective of this study was to assess whether artificial gravity attenuates any long-duration head-down 60 bed rest (HDBR)-induced alterations in motor unit (MU) properties. Methods: Twenty-four healthy participants (16 men; 8 women; 26–54 years) underwent 60-day HDBR with (n = 16) or without (n = 8) 30 min artificial gravity daily induced by whole-body centrifugation. Compound muscle action potential (CMAP), MU number (MUNIX) and MU size (MUSIX) were estimated using the method of Motor Unit Number Index in the Abductor digiti minimi and tibialis anterior muscles 5 days before (BDC-5), and during day 4 (HDT4) and 59 (HDT59) of HDBR. Results: The CMAP, MUNIX, and MUSIX at baseline did not change significantly in either muscle, irrespective of the intervention (p > 0.05). Across groups, there were no significant differences in any variable during HDBR, compared to BDC-5. Conclusion: Sixty days of HDBR with or without artificial gravity does not induce alterations in motor unit number and size in the ADM or TA muscles in healthy individuals
Assessment of the reliability of the motor unit size index (MUSIX) in single subject “round-robin” and multi-centre settings
Objective
The motor unit size index (MUSIX) is incorporated into the motor unit number index (MUNIX). Our objective was to assess the intra-/inter-rater reliability of MUSIX in healthy volunteers across single subject “round robin” and multi-centre settings.
Methods
Data were obtained from i). a round-robin assessment in which 12 raters (6 with prior experience and 6 without) assessed six muscles (abductor pollicis brevis, abductor digiti minimi, biceps brachii, tibialis anterior, extensor digitorum brevis and abductor hallucis) and ii). a multi-centre study with 6 centres studying the same muscles in 66 healthy volunteers. Intra/inter-rater data were provided by 5 centres, 1 centre provided only intra-rater data.
Intra/inter-rater variability was assessed using the coefficient of variation (COV), Bland-Altman plots, bias and 95% limits of agreement.
Results
In the round-robin assessment intra-rater COVs for MUSIX ranged from 7.8% to 28.4%. Inter-rater variability was between 7.8% and 16.2%. Prior experience did not impact on MUSIX values. In the multi-centre study MUSIX was more consistent than the MUNIX. Abductor hallucis was the least reliable muscle.
Conclusions
The MUSIX is a reliable neurophysiological biomarker of reinnervation.
Significance
MUSIX could provide insights into the pathophysiology of a range of neuromuscular disorders, providing a quantitative biomarker of reinnervation
Behaviour of motor unit action potential rate, estimated from surface EMG, as a measure of muscle activation level
BACKGROUND: Surface electromyography (EMG) parameters such as root-mean-square value (RMS) are commonly used to assess the muscle activation level that is imposed by the central nervous system (CNS). However, RMS is influenced not only by motor control aspects, but also by peripheral properties of the muscle and recording setup. To assess motor control separately, the number of motor unit action potentials (MUAPs) per second, or MUAP Rate (MR) is a potentially useful measure. MR is the sum of the firing rates of the contributing MUs and as such reflects the two parameters that the CNS uses for motor control: number of MUs and firing rate. MR can be estimated from multi-channel surface EMG recordings. The objective of this study was to explore the behaviour of estimated MR (eMR) in relation to number of active MUs and firing rate. Furthermore, the influence of parameters related to peripheral muscle properties and recording setup (number of fibers per MU, fiber diameter, thickness of the subcutaneous layer, signal-to-noise-ratio) on eMR was compared with their influence on RMS. METHODS: Physiological parameters were varied in a simulation model that generated multi-channel EMG signals. The behaviour of eMR in simulated conditions was compared with its behaviour in experimental conditions. Experimental data was obtained from the upper trapezius muscle during a shoulder elevation task (20–100 N). RESULTS: The simulations showed strong, monotonously increasing relations between eMR and number of active MUs and firing rate (r(2 )> 0.95). Because of unrecognized superimpositions of MUAPs, eMR was substantially lower than the actual MUAP Rate (aMR). The percentage of detected MUAPs decreased with aMR, but the relation between eMR and aMR was rather stable in all simulated conditions. In contrast to RMS, eMR was not affected by number of fibers per MU, fiber diameter and thickness of the subcutaneous layer. Experimental data showed a strong relation between eMR and force (individual second order polynomial regression: 0.96 < r(2 )< 0.99). CONCLUSION: Although the actual number of MUAPs in the signal cannot be accurately extracted with the present method, the stability of the relation between eMR and aMR and its independence of muscle properties make eMR a suitable parameter to assess the input from the CNS to the muscle at low contraction levels non-invasively
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