Search results for "Control"
showing 10 items of 13168 documents
A new method to calculate external mechanical work using force-platform data in ecological situations in humans: Application to Parkinson's disease
2016
Abstract Background and aim To accurately quantify the cost of physical activity and to evaluate the different components of energy expenditure in humans, it is necessary to evaluate external mechanical work ( W EXT ). Large platform systems surpass other currently used techniques. Here, we describe a calculation method for force-platforms to calculate long-term W EXT . Methods Each force-platform (2.46 × 1.60 m and 3.80 × 2.48 m) rests on 4 piezoelectric sensors. During long periods of recording, a drift in the speed of displacement of the center of mass (necessary to calculate W EXT ) is generated. To suppress this drift, wavelet decomposition is used to low-pass filter the source signal.…
Eye-Hand Coordination in Rhythmical Pointing
2009
International audience; The authors investigated the relation between hand kinematics and eye movements in 2 variants of a rhythmical Fitts's task in which eye movements were necessary or not necessary. P. M. Fitts's (1954) law held in both conditions with similar slope and marginal differences in hand-kinematic patterns and movement continuity. Movement continuity and eye-hand synchronization were more directly related to movement time than to task index of difficulty. When movement time was decreased to fewer than 350 ms, eye-hand synchronization switched from continuous monitoring to intermittent control. The 1:1 frequency ratio with stable pi/6 relative phase changed for 1:3 and 1:5 fre…
Concomitant dental injuries in maxillofacial fractures - a retrospective analysis of 1219 patients
2014
BACKGROUND/AIM: Traumatic dental injuries are frequently combined with maxillofacial fractures, but literature addressing this topic is rare. In a retrospective study, the frequency of dental lesions in inpatients with traumatic facial injuries was analyzed. MATERIAL AND METHODS: All patients referred to the Department of Oral and Maxillofacial Surgery of the University Medical Center of the Johannes Gutenberg-University Mainz for inpatient treatment due to facial fractures between January 2001 and December 2007 were analyzed regarding the type of fracture, its localization, and potential concomitant dental injuries. In addition a systematic review was performed to compare the findings of t…
Efficacy and effectiveness of individual family intervention on social and clinical functioning and family burden in severe schizophrenia: a 2-year r…
2009
BackgroundEmpirical evidence of the efficacy and effectiveness of psychosocial family intervention and of the specificity of its effects on the course of schizophrenia is limited. The aim was to study the efficacy and effectiveness of psychosocial family intervention with regard to clinical and social functioning and family burden after controlling for compliance and several prognostic factors.MethodA 2-year randomized controlled trial with blind assessments. Fifty patients with DSM-IV schizophrenia and persistent positive symptoms and/or previous clinical relapse were allocated to psychosocial family intervention, individual counselling and standard treatment versus individual counselling …
Rifle-balancing in precision shooting:behavioral aspects and psychophysiological implication
2007
This study investigated sharpshooters' strategies to control their rifle stability during the aiming period. Six elite and six pre-elite shooters completed a simulated realistic shooting task (laser rifle), and their performance was evaluated from behavioral and psychophysiological perspectives. The analysis of the rifle's barrel movement, indexing the shooter's behavioral performance, supported the view that rifle-balancing is an essential determinant of superior shooting performance. The psychophysiological data, i.e. the brain slow potentials, suggested that the shooters applied different rifle-hold strategies; the elite shooters concentrated primarily on achieving a stable rifle positio…
Tri-dimensional and triphasic muscle organization of whole-body pointing movements.
2010
Previous kinematic and kinetic studies revealed that, when accomplishing a whole-body pointing task beyond arm's length, a modular and flexible organization could represent a robust solution to control simultaneously target pointing and equilibrium maintenance. Here, we investigated the underlying mechanisms that produce such a coordinative kinematic structure. We monitored the activity of a large number of muscles spread throughout subjects' bodies while they performed pointing movements beyond arm's length, either with or without imposition of postural or pointing constraints. Analyses revealed that muscle signals lied on a tri-dimensional hyper-plane and were temporally organized accordi…
No evidence for attenuated stress-induced extrastriatal dopamine signaling in psychotic disorder
2015
AbstractStress is an important risk factor in the etiology of psychotic disorder. Preclinical work has shown that stress primarily increases dopamine (DA) transmission in the frontal cortex. Given that DA-mediated hypofrontality is hypothesized to be a cardinal feature of psychotic disorder, stress-related extrastriatal DA release may be altered in psychotic disorder. Here we quantified for the first time stress-induced extrastriatal DA release and the spatial extent of extrastriatal DA release in individuals with non-affective psychotic disorder (NAPD). Twelve healthy volunteers (HV) and 12 matched drug-free NAPD patients underwent a single infusion [18F]fallypride positron emission tomogr…
Short-term Effects of the Flavour of Drinks on Ingestive Behaviours in Man
1998
To examine the influence of the oro-sensory properties of different beverages on spontaneous intake of drinks, and the consequence of the volume of fluid ingested on subsequent food intake, 24 subjects (12 men, 12 women), slightly dehydrated, had access ad libitum, during four different experimental sessions in a cross-over design, to one of four commercial beverages without any other drink. The four beverages differed in flavour and caloric content: mineral water; the same mineral water flavoured with orange and unsweetened; the same mineral water flavoured with orange and sweetened with 100 g/l sucrose; or equally sweetened with 50 mg/l aspartame. Ad libitum: lunch was served 15 min after…
Causal transfer function analysis to describe closed loop interactions between cardiovascular and cardiorespiratory variability signals
2004
Although the concept of transfer function is intrinsically related to an input-output relationship, the traditional and widely used estimation method merges both feedback and feedforward interactions between the two analyzed signals. This limitation may endanger the reliability of transfer function analysis in biological systems characterized by closed loop interactions. In this study, a method for estimating the transfer function between closed loop interacting signals was proposed and validated in the field of cardiovascular and cardiorespiratory variability. The two analyzed signals x and y were described by a bivariate autoregressive model, and the causal transfer function from x to y w…
Deterministic chaos and the first positive Lyapunov exponent: a nonlinear analysis of the human electroencephalogram during sleep
1993
Under selected conditions, nonlinear dynamical systems, which can be described by deterministic models, are able to generate so-called deterministic chaos. In this case the dynamics show a sensitive dependence on initial conditions, which means that different states of a system, being arbitrarily close initially, will become macroscopically separated for sufficiently long times. In this sense, the unpredictability of the EEG might be a basic phenomenon of its chaotic character. Recent investigations of the dimensionality of EEG attractors in phase space have led to the assumption that the EEG can be regarded as a deterministic process which should not be mistaken for simple noise. The calcu…