The use of nicotine amongst professional and elite athletes is high, with anecdotal evidence indicating increased prevalence amongst cycling sports. However, previous investigations into its effects ...on performance have not used high-validity or -reliability protocols nor trained cyclists. Therefore, the present study determined whether nicotine administration proved ergogenic during a ∼1 h self-paced cycling time-trial (TT). Ten well-trained male cyclists (34 ± 9 years; 71 ± 8 kg; O
max: 71 ± 6 ml ⋅ kg
⋅ min
) completed three work-dependent TT following ∼30 min administration of 2 mg nicotine gum (GUM), ∼10 h administration of 7 mg ⋅ 24 h
nicotine patch (PAT) or color- and flavor-matched placebos (PLA) in a randomized, crossover, and double blind design. Measures of nicotine's primary metabolite (cotinine), core body temperature, heart rate, blood biochemistry (pH, HCO
, La
) and Borg's rating of perceived exertion (RPE) accompanied performance measures of time and power output. Plasma concentrations of cotinine were highest for PAT, followed by GUM, then PLA, respectively (
< 0.01). GUM and PAT resulted in no significant improvement in performance time compared to PLA (62.9 ± 4.1 min, 62.6 ± 4.5 min, and 63.3 ± 4.1 min, respectively;
= 0.73), with mean power outputs of 264 ± 31, 265 ± 32, and 263 ± 33 W, respectively (
= 0.74). Core body temperature was similar between trials (
= 0.33) whilst HR averaged 170 ± 10, 170 ± 11, and 171 ± 11 beats ⋅ min
(
= 0.60) for GUM, PAT, and PLA, respectively. There were no differences between trials for any blood biochemistry (all
> 0.46) or RPE with mean values of 16.7 ± 0.9, 16.8 ± 0.7, and 16.8 ± 0.8 (
= 0.89) for GUM, PAT, and PLA, respectively. In conclusion: (i) nicotine administration, whether via gum or transdermal patch, did not exert an ergogenic or ergolytic effect on self-paced cycling performance of ∼1 h; (ii) systemic delivery of nicotine was greatest when using a transdermal patch; and (iii) nicotine administration did not alter any of the psycho-physiological measures observed.
The Intracarotid amobarbital test (IAT), also called Wada test, is considered the "gold standard" for lateralizing language dominance in the pre-surgical evaluation of patients with epilepsy. In ...addition, it has been further modified to assess the postoperative risk of amnesia in patients undergoing temporal lobectomy. Since then it has been utilized to lateralize language and assess pre-surgical memory function. Over the years, its popularity has declined due to several limitations and availability of alternative procedures like fMRI and MEG. A survey of its use in the pre-surgical evaluation for epilepsy surgery has not been performed since the 2008 international survey by Baxendale et al. and it was heavily skewed due to data from European and North American countries. Only approximately 12% of the epilepsy centers indicated that they used the Wada test in every patient to assess preoperative memory function and language lateralization before temporal lobectomy. Nowadays, we have many functional mapping tools at our disposal. It has become somewhat unsuitable to have epilepsy patients undergo an invasive test such as the Wada test for the risks associated with it outweigh the benefits. Our objective is to review the Wada Test and alternative methods of assessing language and memory dominance, as it is past its prime and should only be used in specific circumstances.
•Restricted six-body problem with central-body square configuration is investigated.•Cases of twelve and twenty libration points are explained in detail using contour plots and the distribution of ...potential funtion is also described.•The multivariate form of Newton-Raphson method are used to explore the basin of attraction.•Basin of attraction for possible values of the parameter mass ratio is explained and related data are presented in the form of tables and graphs.•Pie-Charts are shown to explain the number of iterations needed for the convergence of initial conditions (one million in each case).•Existence of unpredictable region throughout the basin of attraction and along the boundaries are examined using the method of basin entropy.•Existence of Wada basin boundary is shown in case of twenty libration points.
The present work deals with the recently introduced restricted six body-problem with square configuration. We have computed and verified the position of libration points with the help of Newton-Raphson method. It is observed that the total number of libration points are either twelve or twenty depends upon the mass parameter μ ∈ (0, 0.25). The multivariate form of Newton-Raphson scheme is used to discuss the basins of attraction. Different aspects of the basins of attraction are investigated and explained in detail. The complex combination of the different basins is found along the boundaries. The concept of basin entropy is used to unveil the nature of the boundaries. For μ ∈ (0.215, 0.238), the basins of attraction are unpredictable throughout. It is observed that for all values of the mass parameter μ, the basin boundaries are highly unpredictable. Moreover, we have investigated the presence of Wada basin boundary in the basin of attraction.
Antidoping work is heavily based on scientific analyses of biological material, such as urine and blood. Because of the high stakes both for sports and for the athletes involved it is important that ...analyses are performed and interpreted in agreement with established scientific standards and professional norms. This is not always the case, as we document here. It is our experience that the antidoping movement does not appear willing to consider that errors can occur and should be corrected. The consequences of the lack of transparency and responsibility are carried by unlucky athletes. Scientific, ethical and legal considerations urge the antidoping movement to reform some of their rules and regulations and to include the possibility that the World Anti‐Doping Agency position could, in some cases, be incorrect.
Antidoping efforts depend on rigorous and precise scientific analyses. The World Anti‐Doping Agency (WADA) has a mission to catch dopers; however, there is mounting evidence that the scientific analyses carried out in WADA‐accredited laboratories may not always be interpreted accurately, leading to the prosecution of innocent athletes. Here, Erik Boye and coauthors provide details of two recent cases that highlight the shortfalls in sports‐associated drug testing and the wide impact of such failures.
Chaotic dynamics in open Hamiltonian dynamical systems typically presents a number of fractal structures in phase space derived from the interwoven structure of invariant manifolds and the ...corresponding chaotic saddle. These structures are thought to play an important role in the transport properties related to the chaotic motion. Such properties can explain some aspects of the non-uniform nature of the anomalous transport observed in magnetically confined plasmas. Accordingly we consider a theoretical model for the interaction of charged test particles with drift waves. We describe the exit basin structure of the corresponding chaotic orbit in phase space and interpret it in terms of the invariant manifold structure underlying chaotic dynamics. As a result, the exit basin boundary is shown to be a fractal curve, by direct calculation of its box-counting dimension. Moreover, when there are more than two basins, we verify the existence of the Wada property, an extreme form of fractality.
•Fractal structures are typically found in chaotic orbits of area-preserving dynamical systems, and they influence its transport properties.•We identify a number of fractal structures in a problem of interest in plasma physics: the drift motion of charged particles in a magnetized plasma under the action of two drift waves.•The fractal structures we identify are escape basins, describing its fractal basin structure and also the Wada property.
Numerous studies have shown that language processing is not limited to a few brain areas. Visual or auditory stimuli activate corresponding cortical areas, then memory identifies the word or image, ...Wernicke's and Broca's areas support the processing for either reading/listening or speaking and many areas of the brain are recruited. Determining how a normal person processes language helps clinicians and scientist to understand how brain pathologies such as tumor or stroke can affect changes in language processing. Patients with epilepsy may develop atypical language organization. Over time, the chronic nature of epileptic activity, or changes from a tumor or stroke, can result in a shift of language processing area from the left to the right hemisphere, or re-routing of language pathways from traditional to non-traditional areas within the dominant left hemisphere. It is important to determine where these language areas are prior to brain surgery. MEG evoked responses reflecting cerebral activation of receptive and expressive language processing can be localized using several different techniques: Single equivalent current dipole, current distribution techniques or beamformer techniques. Over the past 20 years there have been at least 25 validated MEG studies that indicate MEG can be used to determine the dominant hemisphere for language processing. The use of MEG neuroimaging techniques is needed to reliably predict altered language networks in patients and to provide identification of language eloquent cortices for localization and lateralization necessary for clinical care.
Summary The Wada test was adapted from the procedure described by Wada in 1964. It still has a role in the prognostic evaluation of memory disorders after mesial temporal lobectomy. The test consists ...of injecting a short-acting anesthetic into one hemisphere, under continuous EEG monitoring and during carotid catheterization, to verify the function of contralateral structures. Intracranial EEG recordings deliver signals with few artifacts, and which are quite specific of the zone explored. Three types of electrodes are in common use: (a) foramen ovale (FO) electrodes: electrodes can be inserted directly, without any stereotactic procedure, to provide easy and comparative EEG recordings of the lower and middle portions of the temporal lobe close to the hippocampus. These allow validation of the temporal lobe origin of seizures using FO electrodes recording coupled with scalp EEG; (b): subdural strip or grip electrodes. This relatively aggressive technique carries infectious and hemorrhagic risks and does not allow the exploration of deep cortical structures. However, it permits precise functional cortical mapping via electrical stimulation because of dense and regular positioning of electrodes over the cortical convexity; (c) stereotactically implanted depth electrodes (stereo-electroencephalography SEEG). Electrodes are individually planned and inserted within the brain parenchyma through small burr holes. This technique is less aggressive than subdural grid exploration. However it offers relatively limited spatial sampling that may be less well adapted to precise functional evaluation. It allows recording from deep cortical structures and can be argued to be the gold standard of presurgical EEG exploration.
Wada property in systems with delay Daza, Alvar; Wagemakers, Alexandre; Sanjuán, Miguel A.F.
Communications in nonlinear science & numerical simulation,
February 2017, 2017-02-00, Letnik:
43
Journal Article
Recenzirano
Odprti dostop
•Transient chaos in systems with delay is investigated.•Two simple delayed systems are introduced.•The delay provides the dimensions that the system needs to exhibit chaos.•Wada property is proved in ...a delayed system for the first time.•Infinite Wada basins can be obtained varying the history functions.
Delay differential equations take into account the transmission time of the information. These delayed signals may turn a predictable system into chaotic, with the usual fractalization of the phase space. In this work, we study the connection between delay and unpredictability, in particular we focus on the Wada property in systems with delay. This topological property gives rise to dramatic changes in the final state for small changes in the history functions.
This paper explores how the credibility of global sport organizations can be renegotiated in a post-scandal context. It draws on a dramaturgical interpretation of social performance and frame ...analysis to analyze how the Athletics Integrity Unit's first years of operation were perceived by its media audience. The results demonstrate that frame consistency, empirical credibility, and the credibility of the frame articulators contributed to the construction of credibility. Besides, transparency and accountability helped to align the athletics authorities’ strategic self-framing with the frames used by external stakeholders. Through the social production of its own performance, the Unit could escape the reputation stigma that has discredited other federations and sport organizations.
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