Search results for "Deceleration"

Effects of Adjacent Vehicles on Judgments of a Lead Car During Car Following.

2016

Objective: Two experiments were conducted to determine whether detection of the onset of a lead car’s deceleration and judgments of its time to contact (TTC) were affected by the presence of vehicles in lanes adjacent to the lead car. Background: In a previous study, TTC judgments of an approaching object by a stationary observer were influenced by an adjacent task-irrelevant approaching object. The implication is that vehicles in lanes adjacent to a lead car could influence a driver’s ability to detect the lead car’s deceleration and to make judgments of its TTC. Method: Displays simulated car-following scenes in which two vehicles in adjacent lanes were either present or absent. Participa…

The location of the tibial accelerometer does influence impact acceleration parameters during running

2016

Tibial accelerations have been associated with a number of running injuries. However, studies attaching the tibial accelerometer on the proximal section are as numerous as those attaching the accelerometer on the distal section. This study aimed to investigate whether accelerometer location influences acceleration parameters commonly reported in running literature. To fulfil this purpose, 30 athletes ran at 2.22, 2.78 and 3.33 m · s–1 with three accelerometers attached with double-sided tape and tightened to the participants’ tolerance on the forehead, the proximal section of the tibia and the distal section of the tibia. Time-domain (peak acceleration, shock attenuation) and frequency-doma…

Habituation and recovery of a slow negative wave of the event-related brain potential.

2002

This study is concerned with the question of whether the late, slow negative wave 2 (SNW2) component of the event-related brain potential is a component of the orienting response (OR). As habituation of the SNW2 would be an argument for such a link with the OR, it was investigated using a variant of the classical repetition/change paradigm. Results supported major claims to be made for a component of the OR: the amplitude of the vertex SNW2 exhibited roughly the typical exponential decline with repeated stimulations (six numeric verbal stimuli presented seriatim in an ascending order) and responded incrementally to a change, at least in a narrow time slot, i.e. it exhibited partial recovery…

Effects of movement direction upon kinematic characteristics of vertical arm pointing movements in man

1998

Vertical arm pointing movements in two directions (upwards and downwards), imposing two different loads (unload and 0.5 kg) and speeds (normal and fast) have been studied in six subjects. Movements were recorded using an optoelectronic system. Data analysis concentrated upon finger-tip kinematics. Significant effects of movement direction were recorded upon velocity profiles. The acceleration time, computed relative to total movement time, was greater for downward movements than for upward movements. In contrast however, no effects of load or speed were observed. Movement time was not affected by movement direction or load, for both speeds tested. These results suggest different planning pr…

Metabolic syndrome in subjects with white-coat hypertension: impact on left ventricular structure and function

2007

Some reports have suggested that white-coat hypertension (WCH) is associated with some features of the metabolic syndrome (MetS). These metabolic disturbances, instead of WCH per se, may potentially explain the greater extent of end-organ damage sometimes observed in WCH subjects (WCHs) when compared to normotensive individuals (NTs). The aim of the present cross-sectional study was to compare left ventricular (LV) structure and function in three groups of subjects: WCHs with MetS, WCHs without MetS and NTs. A total of 145 WCHs, 35% of whom had MetS, were enrolled. As controls, 35 NTs were also studied. In all subjects, routine blood chemistry, echocardiographic examination and 24-h ambulat…

Cosmology with self-adjusting vacuum energy density from a renormalization group fixed point

2001

Cosmologies with a time dependent Newton constant and cosmological constant are investigated. The scale dependence of $G$ and $\Lambda$ is governed by a set of renormalization group equations which is coupled to Einstein's equation in a consistent way. The existence of an infrared attractive renormalization group fixed point is postulated, and the cosmological implications of this assumption are explored. It turns out that in the late Universe the vacuum energy density is automatically adjusted so as to equal precisely the matter energy density, and that the deceleration parameter approaches $q = -1/4$. This scenario might explain the data from recent observations of high redshift type Ia S…

A pulsed high-voltage decelerator system to deliver low-energy antiprotons

2021

International audience; The GBAR (Gravitational Behavior of Antihydrogen at Rest) experiment at CERN requires efficient deceleration of 100 keV antiprotons provided by the new ELENA synchrotron ring to synthesize antihydrogen. This is accomplished using electrostatic deceleration optics and a drift tube that is designed to switch from -99 kV to ground when the antiproton bunch is inside – essentially a charged particle “elevator” – producing a 1 keV pulse. We describe the simulation, design, construction and successful testing of the decelerator device at -92 kV on-line with antiprotons from ELENA.

Imaging of SN 1993J

2005

SN 1993J has been imaged with VLBI, and its angular expansion monitored, for almost ten years. The images show shell-like radio structures with almost circular symmetry. SN 1993J expands according to models of shock excited emission. The angular expansion has a changing deceleration rate and is best modeled with two different slopes. The swept-up mass estimate at an age of 3159 days (∼0.4 M⨀), comparable to the low-mass envelope, favors a binary scenario. The observed spectral index of SN 1993J has slowly flattened since age 1000 days onward (α has changed from −1 to −0.67 at an age of 2820 days).

2018

Beyond the classical paradigm that presents the Anticipatory Postural Adjustments (APAs) as a manner to create forces that counteract disturbances arising from the moving segment during a pointing task, there is a controversial discussion about the role APAs to facilitate the movement and perform a task accurately. In addition, arm kinematics features are classically used to infer the content of motor planning for the execution and the control of arm movements. The present study aimed to disentangle the conflicting role of APAs during an arm-pointing task in which the subjects reach a central diode that suddenly turns on, while their postural stability was manipulated. Three postures were a…

Towards real-time detection of cognitive effort in driving: Contribution of cardiac measurement

2016

En 2013, on estime que 40 à 50% des accidents corporels seraient dus à des défauts d'attention de la part du conducteur. Des études récentes ont mis en évidence la possibilité de détecter des états attentionnels dégradés afin de pouvoir mieux assister le conducteur ; ce thème de recherche représente donc un nouveau gisement de sécurité routière. Cette étude se concentre sur la détection de l'effort cognitif fournit par les conducteurs et cherche, par l'étude de la variation du rythme cardiaque, à identifier un indicateur d'effort sensible sur de courtes fenêtres temporelles.Chacun des 18 participants a passé 8 conditions expérimentales sur simulateur de conduite : la moitié où seule une tâc…