1,721,014 research outputs found
Metaphors and Politics. An Inquyiry into the Political Discourse of the Italian Second republic
No full textRelation between isometric muscle force and surface EMG in intrinsic hand muscles as function of the arm geometry
No full textEvidence exists that shoulder joint geometry influences recruitment efficiency and force-generating capacity of hand muscles [Ginanneschi, F., Del Santo, F., Dominici, F., Gelli, F., Mazzocchio, R., Rossi, A., 2005. Changes in corticomotor excitability of hand muscles in relation to static shoulder positions. Exp. Brain Res. 161 (3), 374-382; Dominici, F., Popa, T., Ginanneschi, F., Mazzocchio, R., Rossi, A., 2005. Cortico-motoneural output to intrinsic hand muscles is differentially influenced by static changes in shoulder positions. Exp. Brain Res. 164 (4), 500-504]. The present study was designed to examine the impact of changing shoulder joint position on the relation between surface EMG amplitude and isometric force production of the abductor digiti minimi muscle (ADM). EMG-force relation of ADM was examined in two shoulder positions: 30 degrees adduction (ANT) and 30 degrees abduction (POST) on the horizontal plane, i.e. under higher and lower force-generating capacity, respectively. The relation was studied over the full range isometric force (10-100% of maximum force in 10% increments, 3 s duration) by analysing root mean square (RMS), median frequency (Mf) of the power spectrum and non-linear recurrence quantification analysis (percentage of determinism: ÞT) of the surface EMG signals. We found that in POST, the slope of the RMS-force relation was significantly higher than in ANT, while its general shape (strictly linear) was preserved. Averaged Mf of the EMG power spectrum was significantly higher in POST that in ANT, while no difference in ÞT was observed between the two shoulder positions. The higher slope of the EMG-force relation in POST than in ANT is interpreted in terms of increased gain of the excitatory drive-firing rate relation. It is concluded that discharge from sensory receptors signalling shoulder position may act to regulate the gain of the excitatory drive-firing rate relation of motoneurones in order to compensate for reduced recruitment efficienc
Il Business Plan come strumento di Pianificazione Strategica: Il caso Fonderia Gelli & f. s.r.l.
No full textL’elaborato è suddiviso in due parti, una prettamente teorica e l’altra applicativa.
La prima parte è a sua volta suddivisa in quattro capitoli.
Nel primo capitolo viene introdotto il Business Plan illustrandone generalità e funzioni nonché limiti e criticità mentre la sua funzione di pianificazione strategica è esposta nel Capitolo 2.
Nel terzo capitolo è introdotto il sistema di pianificazione e controllo descrivendo la metodologia alla base e gli strumenti con cui attuarla.
L’ultimo capitolo riferito alla parte teorica fornisce le linee guida per la corretta elaborazione del Business Plan.
Basandosi su quanto illustrato nella prima parte, nella seconda parte è realizzato un Business Plan finalizzato all’analisi/valutazione della fattibilità economica di un possibile progetto da porre in essere all’interno della Fonderia Carlo Gelli & f. s.r.l.
Changes in corticomotor excitability of forearm muscles in relation to static shoulder positions
No full textWe examined whether the recruitment properties of the corticospinal pathway to forearm muscles are influenced by variations of the shoulder joint angle. Flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles motor evoked potentials (MEPs) in response to transcranial magnetic stimulation were examined during different static positions of shoulder joint in the horizontal plane: from 30 degrees abduction to 30 degrees adduction. We found that at 30 degrees shoulder adduction, maximum slope and plateau phase of the ECR and FCR input-output relationship (i.e., relation between MEP size and stimulus intensity) were significantly higher and lower than at 30 degrees abduction of the shoulder joint, respectively. Intracortical inhibition (ICI) and intracortical facilitation (ICF) of the FCR were assessed using a paired-magnetic pulse paradigm. A significant decrease in ICF was observed after changing shoulder position from 30 degrees abduction to 30 degrees adduction. On the contrary, no variation in the amount of ICI occurred in relation to the same changes in shoulder position. FCR H-reflex to electrical stimulation of median nerve at elbow did not differ significantly between the two shoulder positions. We conclude that shoulder position influences the recruitment efficiency (gain) of the corticospinal volleys to motoneurones of forearm muscles. It is proposed that activity of peripheral receptors signaling static shoulder position influences corticomotor excitability of forearm muscles mainly at cortical level, although C3-C4 propriospinal system could be also involved. It is proposed that the above changes in corticomotoneuronal excitability to forearm muscles as function of shoulder joint position are part of a global proximal-distal synergy operating throughout reaching movements
Messa a punto e funzionamento di un sistema di monitoraggio biologico per il controllo in continuo delle acque potabili.
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Recurrence quantification analysis of surface EMG detects changes in motor unit synchronization induced by recurrent inhibition
No full textAbstract
The systemic injection of L-Acetylcarnitine (L-Ac) induces a reversible increase in recurrent inhibition. In addition, L-Ac potentiation of recurrent inhibition has been found to increase the synchronous activity of single motor units, as detected by traditional linear analysis in the time domain. This result has been recently confirmed using a nonlinear method based on the analysis of embedded determinism (%DET) extracted from the surface EMG. The present study aimed at testing the general applicability of RQA methodology, as a viable tool for assessing motor unit synchronization, by extending the analysis of surface EMG, as revealed by changes in %DET induced by L-Ac, to many upper and lower limb muscles and to muscles that are not easily studied by needle electrodes, such as the orbicularis oculi. Subjects performed brief periods of tonic contractions, alternated to periods of rests to avoid muscle fatigue. Pharmacological enhancement of recurrent inhibition was obtained by a short-lasting intravenous injection of L-Ac. Control experiments were performed replacing L-Ac injection with saline injection. The average %DET showed a significant increase during L-Ac injection in the deltoid, biceps brachii, extensor carpi radialis, while no effect was observed in the opponens pollicis and abductor digiti minimi for the upper limb muscles. Similarly, the average %DET showed a significant increase during L-Ac injection in the quadriceps, soleus, and tibialis anterior, while no effect was observed in the abductor hallucis for the lower limb muscles. RQA of orbicularis oculi muscle activity showed no increase in %DET during L-Ac injection in analogy to what found in the intrinsic muscles of the hand and foot, known to be devoid of recurrent inhibition. The presence or absence of drug-induced increase in motor unit synchronization agrees with the known distribution of recurrent inhibition in the various motor nuclei. The overall significance of these findings is the potential application of RQA methodology as a reliable and independent tool for generally assessing motor unit synchronization from surface EMG under strictly controlled experimental condition.
PMID: 17053906 DOI: 10.1007/s00221-006-0734-x
[Indexed for MEDLINE
- …
