Contributions of ergonomics to the construction of bus drivers health and excellence in public transport and at work

This article is the product of research that analyzed the work of bus drivers of a public transportation company that is considered a benchmark reference in its field of operations, in which it strives to achieve operating excellence. Within this context, the authors sought to understand how such a company has managed to maintain a policy that is capable of reconciling quality public transport while also providing working conditions compatible with the professional development, comfort and health of its workers. Ergonomic work analysis and activity analysis were the guiding elements used in this study. Initial analyses indicate that the activity of drivers includes serving a population and providing mobility for it, which depends on driving the vehicle itself and on relationships with colleagues, users, pedestrians, drivers and others.

Novel cross-coupling reactions between organotellurides and Grignard reagents employing a MnCl2/CuI catalytic system

We present a general protocol for the cross-coupling reaction of Grignard reagents and organic tellurides. Aryl Grignard reagents react stereospecifically with vinyl tellurides in the presence of a catalytic amount of manganese (II) chloride and copper (I) iodide to produce good yields of the corresponding cross-coupling products. (C) 2012 Published by Elsevier Ltd.

Phase-disorder-induced firing activity in excitable neuronal networks with attractive and repulsive coupling

It has been revealed that the network of excitable neurons via attractive coupling can generate spikes under stimuli of subthreshold signals with disordered phases. In this paper, we explore the firing activity induced by phase disorder in excitable neuronal networks consisting of both attractive and repulsive coupling. By increasing the fraction of repulsive coupling, we find that, in the weak coupling strength case, the firing threshold of phase disorder is increased and the system response to subthreshold signals is decreased, indicating that the effect of inducing neuron firing by phase disorder is weakened with repulsive coupling. Interestingly, in the large coupling strength case, we see an opposite situation, where the coupled neurons show a rather large response to the subthreshold signals even with small phase disorder. The latter case implies that the effect of phase disorder is enhanced by repulsive coupling. A system of two-coupled excitable neurons is used to explain the role of repulsive coupling on phase-disorder-induced firing activity.

Contribution of the retrotrapezoid nucleus/parafacial respiratory region to the expiratory-sympathetic coupling in response to peripheral chemoreflex in rats

Moraes DJ, Dias MB, Cavalcanti-Kwiatkoski R, Machado BH, Zoccal DB. Contribution of retrotrapezoid nucleus/parafacial respiratory region to the expiratory-sympathetic coupling in response to peripheral chemoreflex in rats. J Neurophysiol 108: 882-890, 2012. First published May 16, 2012; doi:10.1152/jn.00193.2012.-Central mechanisms of coupling between respiratory and sympathetic systems are essential for the entrainment between the enhanced respiratory drive and sympathoexcitation in response to hypoxia. However, the brainstem nuclei and neuronal network involved in these respiratory-sympathetic interactions remain unclear. Here, we evaluated whether the increase in expiratory activity and expiratory-modulated sympathoexcitation produced by the peripheral chemoreflex activation involves the retrotrapezoid nucleus/parafacial respiratory region (RTN/pFRG). Using decerebrated arterially perfused in situ rat preparations (60-80 g), we recorded the activities of thoracic sympathetic (tSN), phrenic (PN), and abdominal nerves (AbN) as well as the extracellular activity of RTN/pFRG expiratory neurons, and reflex responses to chemoreflex activation were evaluated before and after inactivation of the RTN/pFRG region with muscimol (1 mM). In the RTN/pFRG, we identified late-expiratory (late-E) neurons (n = 5) that were silent at resting but fired coincidently with the emergence of late-E bursts in AbN after peripheral chemoreceptor activation. Bilateral muscimol microinjections into the RTN/pFRG region (n = 6) significantly reduced basal PN frequency, mean AbN activity, and the amplitude of respiratory modulation of tSN (P < 0.05). With respect to peripheral chemoreflex responses, muscimol microinjections in the RTN/pFRG enhanced the PN inspiratory response, abolished the evoked late-E activity of AbN, but did not alter either the magnitude or pattern of the tSN reflex response. These findings indicate that the RTN/pFRG region is critically involved in the processing of the active expiratory response but not of the expiratory-modulated sympathetic response to peripheral chemoreflex activation of rat in situ preparations.

Determination of the critical coupling of explosive synchronization transitions in scale-free networks by mean-field approximations

An explosive synchronization can be observed in scale-free networks when Kuramoto oscillators have natural frequencies equal to their number of connections. The present paper reports on mean-field approximations to determine the critical coupling of such explosive synchronization. It has been verified that the equation obtained for the critical coupling has an inverse dependence on the network average degree. This expression differs from those whose frequency distributions are unimodal and even. In this case, the critical coupling depends on the ratio between the first and second statistical moments of the degree distribution. Numerical simulations were also conducted to verify our analytical results.

Signal amplification of active rotators with phase-shifted coupling

In this paper, we study the signal amplification of coupled active rotators with phase-shifted coupling. We find that the system's response to the external subthreshold signal can be significantly affected by each of the two types of phase-shifted couplings: identical and non-identical phase-shifted couplings. Moreover, through both theoretical analysis and numerical simulations, we have figured out the optimal phase shift, at which the largest signal amplification is generated. These results show that the phase-shifted coupling plays an important role in regulating the system's response to the subthreshold signal.

Using Equivalent Emission Sources to Evaluate the Coupling Between Components

The electromagnetic interference between the electronic systems or their components influences the performance of the systems. For that reason, it is important to model these interferences in order to optimize the position of the systems or their components. In this paper, a method is proposed to construct the equivalent emission source models of systems. The proposed method is based on the multipolar expansion by representing the radiated emission of generic structures in a spherical reference (r, theta, phi). Some results are presented illustrating our method.

Observational study on efficacy of negative expiratory pressure test proposed as screening for obstructive sleep apnea syndrome among commercial interstate bus drivers - protocol study

Abstract Background Obstructive sleep apnea (OSA) is a respiratory disease characterized by the collapse of the extrathoracic airway and has important social implications related to accidents and cardiovascular risk. The main objective of the present study was to investigate whether the drop in expiratory flow and the volume expired in 0.2 s during the application of negative expiratory pressure (NEP) are associated with the presence and severity of OSA in a population of professional interstate bus drivers who travel medium and long distances. Methods/Design An observational, analytic study will be carried out involving adult male subjects of an interstate bus company. Those who agree to participate will undergo a detailed patient history, physical examination involving determination of blood pressure, anthropometric data, circumference measurements (hips, waist and neck), tonsils and Mallampati index. Moreover, specific questionnaires addressing sleep apnea and excessive daytime sleepiness will be administered. Data acquisition will be completely anonymous. Following the medical examination, the participants will perform a spirometry, NEP test and standard overnight polysomnography. The NEP test is performed through the administration of negative pressure at the mouth during expiration. This is a practical test performed while awake and requires little cooperation from the subject. In the absence of expiratory flow limitation, the increase in the pressure gradient between the alveoli and open upper airway caused by NEP results in an increase in expiratory flow. Discussion Despite the abundance of scientific evidence, OSA is still underdiagnosed in the general population. In addition, diagnostic procedures are expensive, and predictive criteria are still unsatisfactory. Because increased upper airway collapsibility is one of the main determinants of OSA, the response to the application of NEP could be a predictor of this disorder. With the enrollment of this study protocol, the expectation is to encounter predictive NEP values for different degrees of OSA in order to contribute toward an early diagnosis of this condition and reduce its impact and complications among commercial interstate bus drivers.

Functional coupling of sensorimotor and associative areas during a catching ball task: a qEEG coherence study

Abstract Background Catching an object is a complex movement that involves not only programming but also effective motor coordination. Such behavior is related to the activation and recruitment of cortical regions that participates in the sensorimotor integration process. This study aimed to elucidate the cortical mechanisms involved in anticipatory actions when performing a task of catching an object in free fall. Methods Quantitative electroencephalography (qEEG) was recorded using a 20-channel EEG system in 20 healthy right-handed participants performed the catching ball task. We used the EEG coherence analysis to investigate subdivisions of alpha (8-12 Hz) and beta (12-30 Hz) bands, which are related to cognitive processing and sensory-motor integration. Results Notwithstanding, we found the main effects for the factor block; for alpha-1, coherence decreased from the first to sixth block, and the opposite effect occurred for alpha-2 and beta-2, with coherence increasing along the blocks. Conclusion It was concluded that to perform successfully our task, which involved anticipatory processes (i.e. feedback mechanisms), subjects exhibited a great involvement of sensory-motor and associative areas, possibly due to organization of information to process visuospatial parameters and further catch the falling object.

Fe valence fluctuations and magnetoelastic coupling in Pb-based multiferroics perovskites

Lead-based multiferroics perovskites with nominal compositions Pb(Fe1/2Nb1/2)O3 and Pb(Fe2/3W1/3)O3 were synthesized following a two-stage method. Magnetic proprieties were investigated and correlated to anelastic proprieties, measured by the conventional pulse-echo method. The discussions are focused in the region around 250 K, where magnetoelectroelastic instabilities have been observed. X-ray absorption nearedge structure (XANES) study further indicates that the edge position varies with temperature revealing a fluctuation on the valence of iron ions with the temperature, which can be related to a variation in anelastic and magnetic proprieties.