Search for Neutrinoless Quadruple-ß Decay of

We report the results of a first experimental search for lepton number violation by four units in the neutrinoless quadruple-ß decay of ^{150}Nd using a total exposure of 0.19 kg yr recorded with the NEMO-3 detector at the Modane Underground Laboratory. We find no evidence of this decay and set lower limits on the half-life in the range T_{1/2}>(1.1-3.2)×10^{21} yr at the 90% C.L., depending on the model used for the kinematic distributions of the emitted electrons.

Measurement of the ßß decay half-life of 130Te with the NEMO-3 detector.

We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of (130)Te in the form of enriched and natural tellurium foils. The ßß decay rate of (130)Te is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T(½)(2ν) = [7.0 ± 0.9(stat) ± 1.1(syst)] × 10(20) yr. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay.

Physiological and behavioural changes associated to the management of secondary tasks while driving.

Sharing attention between two tasks requiring the same mental resources is supposed to increase the resulting strain. Phoning while driving may elicit cognitive interference between driving operations and conversation and consequently, may affect driving efficiency. The road scene cues may thus be perceived late or even omitted, increasing the probability to be involved in a critical situation. The aim of the experiment was to study how the additional strain elicited by a secondary task may change drivers' arousal with potential consequences on driving performance. Electrodermal activity, heart rate and reaction time (RT) were the dependent variables. Listening to the radio, holding an in-vehicle or a cell-phone conversation were the secondary communication tasks, performed by 10 participants during a driving sequence on a private circuit. Within nominal driving, each communication task was requested at random to prevent any habituation or anticipation. The cell-phone conversation made RT increase by about 20%, by comparison to the nominal driving condition. Nevertheless, the in-vehicle conversation impacted RT almost in the same proportion. Physiological data showed that arousal level increased as a function of dual-tasks requirements, the in-vehicle conversation eliciting the same strain as the remote conversation. With caution due to contextual differences between these two communication tasks, conversing with a passenger was thus as detrimental as using a cell-phone.

Physiological and behavioral evaluation of mental load in shared attention tasks.

Hand-held phone use is prohibited by French law to prevent any motor interference with driving. If free-hands kit remains tolerated, its true impact (cognitive interference) is not already clearly determined. This experiment was aimed to study the effect of three communication tasks on driver's behavior: listening to the radio, discussing with a passenger and holding a hands-free phone conversation. Performance was assessed through reaction time (RT) to visual stimuli when driving on a private closed circuit. Drivers were requested to leave their foot from the accelerator pedal when orange lights, placed on the dashboard, switched on. This stimulus was triggered while subjects performed both driving and one of the three additional tasks. Skin resistance level (SRL) and instantaneous heart rate (IHR) were continuously recorded as indices of arousal. Rest and driving were taken as reference. Phoning while driving elicited the highest RT. SRL showed 3 levels of arousal, from the lowest to the highest: rest, driving and the dual task condition (driving + communication). Thus, arousal remained constant whatever the additional task although IHR showed that arousal was higher when phoning than when listening to the radio. Thus, managing two tasks simultanously elicited an increase in subjects' arousal whereas RT increased selectively as a function of the secondary task requirements.