Tragedy on grade crossing: driver failure or systemic fragility?

In 2010, an accident occurred in Americana-SP, Brazil, involving two trains and one bus on a Grade Crossing, when 10 people died and 17 were injured including workers. This paper aims to analyze the accident using the Model of Analysis and Prevention of Work Accidents (MAPA). The method provides observation of work, interviews and analysis of documents to understand precedents of the event in the following stages: to understand the usual work from the involved people, the changes occurred in the system, the operation of barriers, managerial and organizational aspects. By the end, measures are suggested to avoid new occurrences. The accident took place at night in a site with insufficient lighting. The working conditions of bus drivers, train operators and watchmen are inadequate. There were only symbolic barriers (visual and acoustic signals) triggered manually by watchman upon train operator radio communication. The fragility of the barrier system associated to poor lighting and short time to trigger the signaling seem to play a critical role in the event. Contrary to the official report which resulted in guilt of the bus driver, the conclusion of the paper emphasizes the fragility of the safety system and the need of level crossing reproject.

Muscular Dystrophy in Dogs: Does the Crossing of Breeds Influence Disease Phenotype?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influence of visual information on optimal obstacle crossing

Human motion seems to be guided by some optimal principles. In general, it is assumed that human walking is generated with minimal energy consumption. However, in the presence of disturbances during gait, there is a trade-off between stability (avoiding a fall) and energy-consumption. This work analyses the obstacle-crossing with the leading foot. It was hypothesized that energy-saving mechanisms during obstacle-crossing are modulated by the requirement to avoid a fall using the available sensory information, particularly, by vision. A total of fourteen subjects, seven with no visual impairment and seven blind, walked along a 5 meter flat pathway with an obstacle of 0.26 m height located at 3 m from the starting point. The seven subjects with normal vision crossed the obstacle successfully 30 times in two conditions: blindfolded and with normal vision. The seven blind subjects did the same 30 times. The motion of the leading limb was recorded by video at 60 Hz. There were markers placed on the subject's hip, knee, ankle, rear foot, and forefoot. The motion data were filtered with a fourth order Butterworth filter with a cut-off frequency of 4 Hz. The following variables were calculated: horizontal distance between the leading foot and the obstacle at toe-off prior to (DHPO) and after (DHOP) crossing, minimal vertical height from the foot to the obstacle (DVPO), average step velocity (VELOm). The segmental energies were also calculated and the work consumed by the leading limb during the crossing obstacle was computed for each trial. A statistical analysis repeated-measures ANOVA was conducted on these dependent variables revealing significant differences between the vision and non-vision conditions in healthy subjects. In addition, there were no significant differences between the blind and people with vision blindfolded. These results indicate that vision is crucial to determine the optimal trade-off between energy consumption and avoiding a trip during obstacle crossing.

Effects of obstacle height on obstacle crossing in mild Parkinson's disease

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Adaptive Locomotion for Crossing a Moving Obstacle

Crossing moving obstacles requires different space-time adjustments compared with stationary obstacles. Our aim was to investigate gait spatial and temporal parameters in the approach and crossing phases of a moving obstacle. We hypothesized that obstacle speed affects gait parameters, which allow us to distinguish locomotor strategies. Ten young adults walked and stepped over an obstacle that crossed their way perpendicularly, under three obstacle conditions: control-stationary obstacle, slow (1.07 m/s) and fast speed (1.71 m/s) moving obstacles. Gait parameters were different between obstacle conditions, especially on the slow speed. In the fast condition, the participants adopted predictive strategies during the approach and crossing phases. In the slow condition, they used an anticipatory strategy in both phases. We conclude that obstacle speed affects the locomotor behavior and strategies were distinct in the obstacle avoidance phases.

Ploidy, sex and crossing over in an evolutionary aging model

Nowadays, many forms of reproduction coexist in nature: Asexual, Sexual, apomictic and meiotic parthenogenesis, hermaphroditism and parasex. The mechanisms of their evolution and what made them successful reproductive alternatives are very challenging and debated questions. Here, using a simple evolutionary aging model, we give I possible scenario. By studying the performance of Populations where individuals may have diverse characteristics-different ploidies, sex with or without crossing over, as well as the absence of sex-we find all evolution sequence that may explain why there are actually two major or leading groups: Sexual and asexual. We also investigate the dependence of these characteristics on different conditions of fertility and deleterious mutations. Finally, if the primeval organisms oil Earth were, in fact, asexual individuals we conjecture that the sexual form of reproduction could have more easily been set and found its niche during a period of low-intensity mutations. (c) 2005 Elsevier B.V. All rights reserved.

Mitochondrial DNA of Nellore and European x Nellore crossing cattle of high performance

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Phylogenetic relationship between species of genus Cattleya as a function of crossing compatibility

The applicability of the gradcd fertility method in the study of the phylogenctic distance of orchids was investigated with emphasis on the production of F1 hybrid secds with cmbryos. Specics of the genus Cattleya, subgenera Monophyllae, Aurantiacae and Cattleya wece used and the results compared with those obtained with morphological and chemical methods.

Visual timing and adaptive behavior in a road-crossing simulation study

In this road-crossing simulation study, we assessed both participant's ability to visually judge whether or not they could cross a road, and their adaptive walking behavior. To this end, participants were presented with a road inside the laboratory on which a bike approached with different velocities from different distances. Eight children aged 5-7, ten children aged 10-12, and ten adults were asked both to verbally judge whether they could cross the road, and to actually walk across the road if possible. The results indicated that the verbal judgments were not similar to judgments to actually cross the road. With respect to safety and accuracy of judgments, groups did not differ from each other, although the youngest group tended to be more cautious. All groups appeared to use a strategy to cross the road based both on the distance and the velocity of the approaching bike. Young children waited longer on the curb before crossing the road than older children and adults. All groups adjusted their crossing time to the time-to-arrival of the bike. These findings are discussed in relation to the ecological psychological approach and the putative dissociation between vision for perception (i.e. verbal judgment) and vision for action (i.e. actual crossing). (c) 2004 Elsevier Ltd. All rights reserved.

Safety in road crossing of children with cerebral palsy

Aim: Children with cerebral palsy (CP) are regularly confronted with physical constraints during locomotion. Because abnormalities in motor control are often related to perceptual deficits, the aim of this study was to find out whether children with CP were able to walk across a road as safely as their non-handicapped peers. Method: Ten children with CP and 10 non-handicapped children aged 4-14 y were asked to cross a simulated road if they felt the situation was safe. Results: With respect to safety and accuracy of crossings, the behaviour of children with CP was comparable with that of non-handicapped children. However, a closer examination of children's individual crossing behaviour showed considerable differences within the CP group. In contrast to children with damage to the left hemisphere, children with damage to the right hemisphere made unsafe decisions and did not compensate for them by increasing walking speed.Conclusion: the differences in unsafe behaviour and in the ability to compensate for it within the group of children with CP might be related to damage to specific regions of the brain that are involved in the processing of spatial or temporal information.

Level crossing rate of Nakagami-m fading signal: Field trials and validation

Field trial measurements are used to validate the level crossing rate formula derived in an exact manner recently for the Nakagami-m signal. The formula reveals an excellent fit to measurements in situations other than those for which the Rice model is more appropriate.

Induction of mitotic crossing-over in diploid strains of Aspergillus nidulans using low-dose X-rays

As a contribution towards detecting the genetic effects of low doses of genotoxic physical agents, this paper deals with the consequences of low-dose X-rays in the Aspergillus nidulans genome. The irradiation doses studied were those commonly used in dental clinics (1-5 cGy). Even very low doses promoted increased mitotic crossing-over frequencies in diploid strains heterozygous for several genetic markers including the ones involved in DNA repair and recombination mechanisms. Genetic markers of several heterozygous strains were individually analyzed disclosing that some markers were especially sensitive to the treatments. These markers should be chosen as bio-indicators in the homozygotization index assay to better detect the recombinogenic/ carcinogenic genomic effects of low-dose X-rays. ©FUNPEC-RP.

Influence of visual feedback sampling on obstacle crossing behavior in people with Parkinson's disease

The purpose of the current study was to investigate the role of visual information on gait control in people with Parkinson's disease as they crossed over obstacles. Twelve healthy individuals, and 12 patients with mild to moderate Parkinson's disease, walked at their preferred speeds along a walkway and stepped over obstacles of varying heights (ankle height or half-knee height), under three visual sampling conditions: dynamic (normal lighting), static (static visual samples, similar to stroboscopic lighting), and voluntary visual sampling. Subjects wore liquid crystal glasses for visual manipulation. In the static visual sampling condition only, the patients with Parkinson's disease made contact with the obstacle more often than did the control subjects. In the successful trials, the patients increased their crossing step width in the static visual sampling condition as compared to the dynamic and voluntary visual sampling conditions; the control group maintained the same step width for all visual sampling conditions. The patients showed lower horizontal mean velocity values during obstacle crossing than did the controls. The patients with Parkinson's disease were more dependent on optic flow information for successful task and postural stability than were the control subjects. Bradykinesia influenced obstacle crossing in the patients with Parkinson's disease. © 2013 Elsevier B.V.