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81.
Assessment of average muscle fiber conduction velocity from surface EMG signals during fatiguing dynamic contractions 总被引:1,自引:0,他引:1
Farina D Pozzo M Merlo E Bottin A Merletti R 《IEEE transactions on bio-medical engineering》2004,51(8):1383-1393
In this paper, we propose techniques of surface electromyographic (EMG) signal detection and processing for the assessment of muscle fiber conduction velocity (CV) during dynamic contractions involving fast movements. The main objectives of the study are: 1) to present multielectrode EMG detection systems specifically designed for dynamic conditions (in particular, for CV estimation); 2) to propose a novel multichannel CV estimation method for application to short EMG signal bursts; and 3) to validate on experimental signals different choices of the processing parameters. Linear adhesive arrays of electrodes are presented for multichannel surface EMG detection during movement. A new multichannel CV estimation algorithm is proposed. The algorithm provides maximum likelihood estimation of CV from a set of surface EMG signals with a window limiting the time interval in which the mean square error (mse) between aligned signals is minimized. The minimization of the windowed mse function is performed in the frequency domain, without limitation in time resolution and with an iterative computationally efficient procedure. The method proposed is applied to signals detected from the vastus laterialis and vastus medialis muscles during cycling at 60 cycles/min. Ten subjects were investigated during a 4-min cycling task. The method provided reliable assessment of muscle fatigue for these subjects during dynamic contractions. 相似文献
82.
Nawroth F Isachenko V Dessole S Rahimi G Farina M Vargiu N Mallmann P Dattena M Capobianco G Peters D Orth I Isachenko E 《Cryo letters》2002,23(2):93-102
The aim of our study was to investigate the effects of vitrification (cooling rate approximately 10000(C/min) without cryoprotectants on swim-up prepared human spermatozoa in comparison to standard conventional freezing with cryoprotectants. Motility, morphology, rate of viability and acrosome reaction of spermatozoa were evaluated. The described method of cryopreservation of human spermatozoa by direct plunging into liquid nitrogen slush without cryoprotectants was effective and could be recommended for routine IVF. 相似文献
83.
A model for the generation of synthetic intramuscular EMG signals to test decomposition algorithms 总被引:2,自引:0,他引:2
As more and more intramuscular electromyogram (EMG) decomposition programs are being developed, there is a growing need for evaluating and comparing their performances. One way to achieve this goal is to generate synthetic EMG signals having known features. Features of interest are: the number of channels acquired (number of detection surfaces), the number of detected motor unit action potential (MUAP) trains, their time-varying firing rates, the degree of shape similarity among MUAPs belonging to the same motor unit (MU) or to different MUs, the degree of MUAP superposition, the MU activation intervals, the amount and type of additive noise. A model is proposed to generate one or more channels of intramuscular EMG starting from a library of real MUAPs represented in a 16-dimensional space using their Associated Hermite expansion. The MUAP shapes, regularity of repetition rate, degree of superposition, activation intervals, etc. may be time variable and are described quantitatively by a number of parameters which define a stochastic process (the model) with known statistical features. The desired amount of noise may be added to the synthetic signal which may then be processed by the decomposition algorithm under test to evaluate its capability of recovering the signal features. 相似文献
84.
We propose a new electromyogram generation and detection model. The volume conductor is described as a nonhomogeneous (layered) and anisotropic medium constituted by muscle, fat and skin tissues. The surface potential detected in space domain is obtained from the application of a two-dimensional spatial filter to the input current density source. The effects of electrode configuration, electrode size and inclination of the fibers with respect to the detection system are included in the transfer function of the filter. Computation of the signal in space domain is performed by applying the Radon transform; this permits to draw considerations about spectral dips and clear misunderstandings in previous theoretical derivations. The effects of generation and extinction of the action potentials at the fiber end plate and at the tendons are included by modeling the source current, without any approximation of its shape, as a function of space and time and by using again the Radon transform. The approach, based on the separation of the temporal and spatial properties of the muscle fiber action potential and of the volume conductor, includes the capacitive tissue properties. 相似文献
85.
A Combined NMR and Computational Approach to Determine the RGDechi‐hCit‐αvβ3 Integrin Recognition Mode in Isolated Cell Membranes 下载免费PDF全文
Dr. Biancamaria Farina Dr. Ivan de Paola Dr. Luigi Russo Dr. Domenica Capasso Dr. Annamaria Liguoro Dr. Annarita Del Gatto Dr. Michele Saviano Prof. Paolo V. Pedone Dr. Sonia Di Gaetano Dr. Gaetano Malgieri Dr. Laura Zaccaro Prof. Roberto Fattorusso 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):681-693
The critical role of integrins in tumor progression and metastasis has stimulated intense efforts to identify pharmacological agents that can modulate integrin function. In recent years, αvβ3 and αvβ5 integrin antagonists were demonstrated to be effective in blocking tumor progression. RGDechi‐hCit, a chimeric peptide containing a cyclic RGD motif linked to an echistatin C‐terminal fragment, is able to recognize selectively αvβ3 integrin both in vitro and in vivo. High‐resolution molecular details of the selective αvβ3 recognition of the peptide are certainly required, nonetheless RGDechi‐hCit internalization limited the use of classical in cell NMR experiments. To overcome such limitations, we used WM266 isolated cellular membranes to accomplish a detailed NMR interaction study that, combined with a computational analysis, provides significant structural insights into αvβ3 molecular recognition by RGDechi‐hCit. Remarkably, on the basis of the identified molecular determinants, we design a RGDechi‐hCit mutant that is selective for αvβ5 integrin. 相似文献
86.
87.
F. Farina Arboccò P. Vermaercke K. Smits L. Sneyers K. Strijckmans 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(3):2063-2069
The current (official) k 0 nuclear data for the cesium radionuclides was determined circa 1987 and was partially adopted from older literature. In this work we aimed at the redetermination of experimental k 0, Q 0 and $\bar{E}$ r factors with metrological care. The results are in good agreement with more recent results from other authors. Our Q 0 and $\bar{E}$ r values were 2–15 and 25 % different, respectively. The k 0 factors were determined according to the cadmium subtraction technique, resulting in values 3–7 % different than the official ones. Our precision and accuracy is discussed. 相似文献
88.
Alberto Farina 《Monatshefte für Mathematik》2003,179(2):265-269
(w, c) ? R2, u ? Lloc3 (RN, C)\font\Opr=msbm10 at 8pt \def\Op#1{\hbox{\Opr{#1}}}(\omega, c)\in {\Op R}^2, {\upsilon} \in L_{\rm loc}^3 ({\Op R}^N, {\bf C}) and x||j||L¥(RN×R)2 £ max{0, 1-w+[(c2)/4]}.\font\Opr=msbm10 at 8pt \def\Op#1{\hbox{\Opr{#1}}}\Vert\varphi\Vert_{L^\infty({\Op R}^N\times{\Op R})}^2 \le \max\bigg\{0, 1-\omega+{c^2\over 4}\bigg\}. 相似文献
89.
90.
Alberto Farina Enrico Valdinoci 《Calculus of Variations and Partial Differential Equations》2008,33(1):1-35
We consider the quasiminima of the energy functional
where and F is a double-well potential. We show that the Lipschitz quasiminima, which satisfy an equipartition of energy condition, possess
density estimates of Caffarelli–Cordoba-type, that is, roughly speaking, the complement of their interfaces occupies a positive
density portion of balls of large radii. From this, it follows that the level sets of the rescaled quasiminima approach locally
uniformly hypersurfaces of quasiminimal perimeter. If the quasiminimum is also a solution of the associated PDE, the limit
hypersurface is shown to have zero mean curvature and a quantitative viscosity bound on the mean curvature of the level sets
is given. In such a case, some Harnack-type inequalities for level sets are obtained and then, if the limit surface if flat,
so are the level sets of the solution.
We thank Ovidiu Savin and Berardino Sciunzi for several interesting discussions. The comments of an anonymous referee have
also been very helpful. This collaboration began during a very pleasant visit of AF to the Università di Roma La Sapienza and Roma Tor Vergata and it has been completed while the authors were visiting the Wolfgang Pauli Institute in Vienna on the occasion of the Summer School on Gross-Pitaevskii equations for superfluids and Bose-Einstein condensates. EV has been partially supported by MIUR Metodi variazionali ed equazioni differenziali nonlineari and GNAMPA Principio del massimo e disuguaglianze di Harnack per equazioni ellittiche e sub-ellittiche. 相似文献