704 research outputs found
Spatial localization of electromyographic amplitude distributions associated to the activation of dorsal forearm muscles
Full text linkIn this study we investigated whether the spatial distribution of surface electromyographic (EMG) amplitude can be used to describe the activation of muscle portions with different biomechanical actions. Ten healthy subjects performed isometric contractions aimed to selectively activate a number of forearm muscles or muscle subportions. Monopolar electromyographic signals were collected with an electrode grid of 128 electrodes placed on the proximal, dorsal portion of the forearm. The monopolar EMG amplitude (root mean square value) distribution was calculated for each contraction, and high-amplitude channels were identified through an automatic procedure; the position of the EMG source was estimated with the barycenter of these channels. Each of the contractions tested was associated to a specific EMG amplitude distribution, whose location in space was consistent with the expected anatomical position of the main agonist muscle (or subportion). The position of each source was significantly different from the others in at least one direction (ANOVA; transversally to the forearm: P < 0.01, F = 125.92; longitudinally: P < 0.01, F = 35.83). With such an approach, we could distinguish the spatial position of EMG distributions related to the activation of contiguous muscles (e.g.: extensor carpi ulnaris and extensor digitorum communis), different heads of the same muscle (i.e.: extensor carpi radialis brevis and longus) and different functional compartments (i.e.: extensor digitorum communis, middle and ring fingers). These findings are discussed in terms of how forces along a given direction can be produced by recruiting population of motor units clustered not only in specific muscles, but also in muscle sub-portions. In addition, this study supports the use of high-density EMG systems to characterize the activation of muscle subportions with different biomechanical actions
Territory and fiber orientation of vastus medialis motor units:A Surface electromyography investigation
No full text Introduction: The aim of this study was to determine whether muscle fibers innervated by single motor neurons are confined in small subvolumes of the vastus medialis (VM) and if motor unit fiber orientation depends on their position within the muscle. Methods: Single motor units were identified from a grid of surface electrodes. The size of their surface representation and fiber orientation were extracted using an algorithm validated on simulated signals. Results: The action potentials of 77 motor units were represented locally on theskin (10th–90th percentiles: 14–25 mm). According to simulations, this indicates territories smaller than 11.8–64.8 mm. Motor units in distal regions of VM had fibers at a greater angle than those in proximal regions (R 5 –0.54, P < 0.001). Conclusion: Motor units with small territories and varying fiber orientations may be an anatomical predisposition to regulate how regions within VM apply forces to the patella. This could help to redistribute loads within the joint in painful conditions
Laser Scanner 3D per la catalogazione dell’Architettura Medioevale: la chiesa di Santa Croce in Bergamo
No full textThe improvement of new active optical sensors has revolutionized the survey method for cultural heritage. The conservation and enhancement of heritage require an extensive documentation both in terms of shape, color and geometry and of more properly historical-artistic features and the incessant development of scientific research today provides new possibilities and tools which is essential to know and use, in the framework of a responsible and conscious research experimentation. In the field of archeology, the automatic 3D survey is now recognized as an "added value" compared to traditional practices and the active contribution that this technology can provide to the interpretative phase, cataloguing and promotion of archeological assets, even through the web, is becoming increasingly clear. On the other hand, even considering the speed of the procedure and the measurement accuracy, there have been calls for reflection on the role that laser scanning can play in the world of archeology. Role that it is appropriate to clarify and positively consolidate even by conducting new studies and experiments, such as the one here presented and concerning the Church of Santa Croce in Bergamo, а small octagonal Romanesque chapel built іn the fіrst half оf the 11th century
Do surface electromyograms provide physiological estimates of conduction velocity from the medial gastrocnemius muscle?
No full textMuscle fiber conduction velocity (CV) is commonly estimated from surface electromyograms (EMGs) collected with electrodes parallel to muscle fibers. If electrodes and muscle fibers are not located in parallel planes, CV estimates are biased towards values far over the physiological range. In virtue of their pinnate architecture, the fibers of muscles such as the gastrocnemius are hardly aligned in planes parallel to surface electrodes. Therefore, in this study we investigate whether physiological CV estimates can be obtained from the gastrocnemius muscle. Specifically, with a large grid of 16×8 electrodes we map CV estimates over the whole gastrocnemius muscle while eleven subjects exerted isometric plantar flexions at three different force levels. CV was estimated for couples of single differential EMGs and estimate locations (i.e., channels) were classified as physiological and non-physiological, depending on whether CV estimates were within the physiological range (3-6ms-1) or not. Physiological CV values could be estimated from a markedly small muscle region for eight participants; channels providing physiological CV estimates corresponded to about 5% of the total number of channels. As expected, physiological and non-physiological channels were clustered in distinct regions. CV estimates within the physiological range were obtained for the most distal gastrocnemius portion (ANOVA, P<0.001), where occurrences of propagating potentials were often verified through visual analysis. For the first time, this study shows that CV might be reliably assessed from surface EMGs collected from the most distal gastrocnemius regio
Nuovi dati per la rilettura e la conoscenza di un ‘rudere monumentale’: la chiesa ‘longobarda’ di Sant’Eusebio a Pavia
No full textLa chiesa di Sant’Eusebio di Pavia, sita in un’area che era il cuore della città in età longobarda, è stata oggetto di attenzione da parte di autorevoli studiosi. La sua importanza è legata alla sua ipotizzata origine di cattedrale ariana successivamente trasformata in tempio cattolico e descritta da Paolo Diacono. La magnificenza del tempo antico è stato oggi dimenticata; ciò che rimane dell’edificio, la sola cripta, è un monumento ‘abbandonato’ e scarsamente valorizzato. Un nuovo studio di Sant’Eusebio è stato possibile all’interno di un più ampio progetto di conoscenza, conservazione e valorizzazione dell’eredità del Regno dei Longobardi che ha dato avvio ad una nuova campagna di rilevamento e di interpretazione delle rimanenze archeologiche. La ricerca, basata su una meticolosa attività analisi storico-archeologica, caratterizzata dall’analisi delle fonti documentarie (tradizionali e complementari) e dalla lettura stratigrafica dei paramenti a vista degli edifici, la ricerca si è distinta per l’uso delle moderne tecnologie di rilevamento, di indagine diagnostica e della rappresentazione digitale. Il contributo vuol proporre le prime riflessioni sulla cripta di Sant’Eusebio frutto di una collaborazione interdisciplinare di un team di archeologi, architetti e ingegneri esperti in rilevamento e conservazione del patrimonio culturale.The church of Sant’Eusebio in Pavia, located in an area that was the heart of the city in the Lombard age, has attracted a multitude of scholars during the time. Its importance is related to its hypothesized origin as an Arian cathedral, later converted into a Catholic temple and described by Paolo Diacono. The magnificence of ancient times has been today forgotten. All that remains of the building is the crypt: an ‘abandoned’ and scarcely valued monument that deserves to be further investigated and valorised. A new study has then been carried out within a larger project of knowledge, conservation and enhancement of the legacy of the Lombard Kingdom. The research, based on a meticulous historical-archaeological inquiry, was characterized by the study of documentary sources (traditional and complementary) and the stratigraphic analysis of the masonries. The project was characterized by the use of modern survey and diagnostic technologies as well as of the most innovative tools of digital representation. This essay, founded on the interdisciplinary collaboration of a team of archaeologists, architects and engineers experts in survey, analysis and preservation of cultural heritage, intends to present the first results obtained
The Pottesman Collection in the British Museum. Early Dynastic and Sargonic administrative texts. With an Appendix on a Palmyrene Inscription
No full textEdizione, trascrizione, traduzione e commento di un frammento di iscrizione palmirena inedita presente nella collezione Pottesman del British Museum (Appendice Agostini).The British Museum houses a small collection of six cuneiform tablets and a Palmyrene dedicatory inscription purchased in 1987 from the private collection of Solomon Pottesman. The aim of the present contribution is to provide a catalog of this lot and an edition of the so far unpublished cuneiform texts. In the appendix, Alessio Agostini added the edition of the Palmyrene inscription, which would have otherwise gone beyond the capabilities of the present author
Physiological plasticity and life history traits affect Chamelea gallina acclimatory responses during a marine heatwave
Full text linkThe striped venus clam (Chamelea gallina) is a relevant economic resource in the Adriatic Sea. This study explored
the physiological status of C. gallina at four sites selected along a gradient from high to low incidence of recorded
historical mortality events and low to high productivity in the Northwestern Adriatic Sea. Investigations were
performed during the marine heatwave in 2022 (from July to November). The optimal temperature range for
C. gallina was exceeded in July and September, exacerbating stress conditions and a poor nutritional status,
particularly at the low productivity sites. Transcriptional profiles assessed in digestive glands showed that clams
from the low productivity sites up-regulated transcripts related to feeding/digestive functions as a possible
compensatory mechanism to withstand adverse environmental conditions. Clams from the high productivity
sites, that in a previous study showed enrichment of health-promoting microbiome components, displayed a
healthier metabolic makeup (IDH up-regulation) and induction of protective antioxidant and immune responses.
These features are hallmarks of putative enhanced resilience of the species towards environmental stress. Despite
the well-known high sensitivity of C. gallina to environmental variations and its narrow window of acclimatory
potential, results highlight that local conditions may influence physiological plasticity of this clam species and
shape either positively or negatively its response capabilities to environmental changes. The identification of
health-promoting endogenous mechanisms both from the animal (this study) and from its associated microbiome
may provide the foundation for developing novel tools and strategies to improve clam health and production in
low productivity areas or under adverse environmental conditions
Recensione di Cecilia Falchini (2023). Ruperto di deutz - Un’intima familiarità. Antologia, Edizioni Qiqajon (Comunità di Bose), Magnano (Bi), 281 pp.
No full textReview of Cecilia Falchini (2023). Ruperto di deutz - Un’intima familiarità. Antologia, Edizioni Qiqajon (Comunità di Bose), Magnano (Bi), 281 pp.
Author: Alessio MagogaRecensione di Cecilia Falchini (2023). Ruperto di deutz - Un’intima familiarità. Antologia, Edizioni Qiqajon (Comunità di Bose), Magnano (Bi), 281 pp.
Autor: Alessio Magog
Handheld-Impedance-Measurement System with seven-decade capability and potentiostatic function
Full text linkThis paper describes design and test of a new impedance-measurement system for nonlinear devices that exhibits a seven-decade range and works down to a frequency of 0.01 Hz. The system is specifically designed for electrochemical measurements, but the proposed architecture can be employed in many other fields where flexible signal generation and analysis are required. The system employs an unconventional signal generator based on two pulsewidth modulation (PWM) oscillators and an autocalibration system that allows uncertainties of less than 3% to be obtained over a range of 1 kΩ to 100 GΩ. A synchronous demodulation processing allows the noise superimposed to the low-amplitude input signals to be made negligibl
Uneven spatial distribution of surface EMG: what does it mean?
No full textThe aim of this work is to show how changes in surface electromyographic activity (sEMG) during a repetitive, non-constant force contraction can be detected and interpreted on the basis of the amplitude distribution provided by high-density sEMG techniques. Twelve healthy male subjects performed isometric shoulder elevations, repeating five times a force ramp profile up to 25 % of the maximal voluntary contraction (MVC). A 64-electrode matrix was used to detect sEMG from the trapezius muscle. The sEMG amplitude distribution was obtained for the force levels in the range 5-25 % MVC with steps of 5 % MVC. The effect of force level, subject, electrode position and ramp repetition on the sEMG amplitude distribution was tested. The sEMG amplitude was significantly smaller in the columns of the electrode grid over the tendons (repeated measures ANOVA, p < 0.01). The barycentre of the distribution of sEMG amplitude was subject-specific (Kruskal-Wallis test, p < 0.01), and shifted caudally with the increase of force levels and cranially with the repetition of the motor task (both p < 0.01, repeated measures ANOVA). The results are discussed in terms of motor unit recruitment in different muscle sub-portions. It is concluded that the sEMG amplitude distribution obtained by multichannel techniques provides useful information in the study of muscle activity, and that changes in the spatial distribution of the recruited motor units during a force varying isometric contraction might partially explain the variability observed in the activation pattern of the upper trapezius muscl
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