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DYNA , 2011,
Abstract: in this study, a failure analysis of the wheel shafts of wagons for transporting sugar cane is carried out. several shafts have broken with a small fatigue propagation zone and a large sudden-fracture zone. the material and load condition of the shafts were examined. stress measurements on a vehicle with a similar suspension system were conducted to find the dynamic loads and calculate the impact factor. an impact factor higher than the one reported in the literature was found. according the manufactures, aisi 1045 steel was the material of the shaft; however, it was found that the material of some shafts did not have the specifications of aisi 1045 steel. moreover, even if the shafts were made with good quality aisi 1045 steel, the stresses are so high that the element will fail due to fatigue. finally, some recommendations are given to increase the reliability of the shafts, and a new design and manufacturing process are proposed
Inferior Parietal Lobe Activity in Visuo-Motor Integration during the Robot Hand Illusion  [PDF]
Mohamad Arif Fahmi Bin Ismail, Sotaro Shimada
Psychology (PSYCH) , 2018, DOI: 10.4236/psych.2018.915174
Abstract: The robot hand illusion (RoHI) is the participant’s illusion of the self-ownership and the self-agency of a robot hand that appears to be moving consistently with their own hand, and feel as if the robot hand belongs to them. Mismatching between motor and visual information disrupt the effect of RoHI respect to the robot hand. In our previous study, we found that participants felt that the virtual hand was their own when the visual feedback was delayed by less than 200 ms. Moreover, although they did not feel that the virtual hand was their own, the participants felt that they could control the virtual hand even with a visual delay of 300 - 500 ms. Here, we used near-infrared spectroscopy (NIRS) to investigate brain activity associated with the RoHI under different delayed visual feedback conditions (100 ms, 400 ms, and 700 ms). We found significant activation in the supramarginal gyrus and superior temporal gyrus in the 100 ms feedback delay condition. An ANOVA indicated that this activation was significantly different from that in other conditions (p < 0.01). These results demonstrate that activity in the inferior parietal cortex was modulated by the delay between the motor command and the visual feedback regarding the movement of the robot hand. We propose that the inferior parietal lobe is essential for integrating motor and visual information that enables one to distinguish their own body from those of others.
Effect of Transcranial Magnetic Stimulation (TMS) on Parietal and Premotor Cortex during Planning of Reaching Movements  [PDF]
Pierpaolo Busan, Claudia Barbera, Mauro Semenic, Fabrizio Monti, Gilberto Pizzolato, Giovanna Pelamatti, Piero Paolo Battaglini
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004621
Abstract: Background Cerebral activation during planning of reaching movements occurs both in the superior parietal lobule (SPL) and premotor cortex (PM), and their activation seems to take place in parallel. Methodology The activation of the SPL and PM has been investigated using transcranial magnetic stimulation (TMS) during planning of reaching movements under visual guidance. Principal Findings A facilitory effect was found when TMS was delivered on the parietal cortex at about half of the time from sight of the target to hand movement, independently of target location in space. Furthermore, at the same stimulation time, a similar facilitory effect was found in PM, which is probably related to movement preparation. Conclusions This data contributes to the understanding of cortical dynamics in the parieto-frontal network, and suggests that it is possible to interfere with the planning of reaching movements at different cortical points within a particular time window. Since similar effects may be produced at similar times on both the SPL and PM, parallel processing of visuomotor information is likely to take place in these regions.
Behavioral and Electrophysiological Effects of Transcranial Direct Current Stimulation of the Parietal Cortex in a Visuo-Spatial Working Memory Task  [PDF]
T. Zaehle
Frontiers in Psychiatry , 2012, DOI: 10.3389/fpsyt.2012.00056
Abstract: Impairments of working memory (WM) performance are frequent concomitant symptoms in several psychiatric and neurologic diseases. Despite the great advance in treating the reduced WM abilities in patients suffering from, e.g., Parkinson’s and Alzheimer’s disease by means of transcranial direct current stimulation (tDCS), the exact neurophysiological underpinning subserving these therapeutic tDCS-effects are still unknown. In the present study we investigated the impact of tDCS on performance in a visuo-spatial WM task and its underlying neural activity. In three experimental sessions, participants performed a delayed matching-to-sample WM task after sham, anodal, and cathodal tDCS over the right parietal cortex. The results showed that tDCS modulated WM performance and its underlying electrophysiological brain activity in a polarity-specific way. Parietal tDCS altered event-related potentials and oscillatory power in the alpha band at posterior electrode sites. The present study demonstrates that posterior tDCS can alter visuo-spatial WM performance by modulating the underlying neural activity. This result can be considered an important step toward a better understanding of the mechanisms involved in tDCS-induced modulations of cognitive processing. This is of particular importance for the application of electrical brain stimulation as a therapeutic treatment of neuropsychiatric deficits in clinical populations.
Illusory Sensation of Movement Induced by Repetitive Transcranial Magnetic Stimulation  [PDF]
Mark Schram Christensen,Jesper Lundbye-Jensen,Michael James Grey,Alexandra Damgaard Vejlby,Bo Belhage,Jens Bo Nielsen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0013301
Abstract: Human movement sense relies on both somatosensory feedback and on knowledge of the motor commands used to produce the movement. We have induced a movement illusion using repetitive transcranial magnetic stimulation over primary motor cortex and dorsal premotor cortex in the absence of limb movement and its associated somatosensory feedback. Afferent and efferent neural signalling was abolished in the arm with ischemic nerve block, and in the leg with spinal nerve block. Movement sensation was assessed following trains of high-frequency repetitive transcranial magnetic stimulation applied over primary motor cortex, dorsal premotor cortex, and a control area (posterior parietal cortex). Magnetic stimulation over primary motor cortex and dorsal premotor cortex produced a movement sensation that was significantly greater than stimulation over the control region. Movement sensation after dorsal premotor cortex stimulation was less affected by sensory and motor deprivation than was primary motor cortex stimulation. We propose that repetitive transcranial magnetic stimulation over dorsal premotor cortex produces a corollary discharge that is perceived as movement.
Effect of Parietal Transcranial Magnetic Stimulation on Spatial Working Memory in Healthy Elderly Persons - Comparison of Near Infrared Spectroscopy for Young and Elderly  [PDF]
Kaori Yamanaka, Hiroi Tomioka, Shingo Kawasaki, Yumiko Noda, Bun Yamagata, Akira Iwanami, Masaru Mimura
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102306
Abstract: In a previous study, we succeeded in improving the spatial working memory (WM) performance in healthy young persons by applying transcranial magnetic stimulation (TMS) to the parietal cortex and simultaneously measuring the oxygenated hemoglobin (oxy-Hb) level using near-infrared spectroscopy (NIRS). Since an improvement in WM was observed when TMS was applied to the right parietal cortex, the oxy-Hb distribution seemed to support a model of hemispheric asymmetry (HA). In the present study, we used the same study design to evaluate healthy elderly persons and investigated the effect of TMS on WM performance in the elderly, comparing the results with those previously obtained from young persons. The application of TMS did not affect WM performance (both reaction time and accuracy) of 38 elderly participants (mean age = 72.5 years old). To investigate the reason for this result, we conducted a three-way ANOVA examining oxy-Hb in both young and elderly participants. For the right parietal TMS site in the elderly, TMS significantly decreased the oxy-Hb level during WM performance; this result was the opposite of that observed in young participants. An additional three-way ANOVA was conducted for each of the 52 channels, and a P value distribution map was created. The P value maps for the young participants showed a clearly localized TMS effect for both the WM and control task, whereas the P map for the elderly participants showed less significant channels and localization. Further analysis following the time course revealed that right-side parietal TMS had almost no effect on the frontal cortex in the elderly participants. This result can most likely be explained by age-related differences in HA arising from the over-recruitment of oxy-Hb, differentiation in the parietal cortex, and age-related alterations of the frontal-parietal networks.
Functional Interaction between Right Parietal and Bilateral Frontal Cortices during Visual Search Tasks Revealed Using Functional Magnetic Imaging and Transcranial Direct Current Stimulation  [PDF]
Amanda Ellison, Keira L. Ball, Peter Moseley, James Dowsett, Daniel T. Smith, Susanne Weis, Alison R. Lane
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093767
Abstract: The existence of a network of brain regions which are activated when one undertakes a difficult visual search task is well established. Two primary nodes on this network are right posterior parietal cortex (rPPC) and right frontal eye fields. Both have been shown to be involved in the orientation of attention, but the contingency that the activity of one of these areas has on the other is less clear. We sought to investigate this question by using transcranial direct current stimulation (tDCS) to selectively decrease activity in rPPC and then asking participants to perform a visual search task whilst undergoing functional magnetic resonance imaging. Comparison with a condition in which sham tDCS was applied revealed that cathodal tDCS over rPPC causes a selective bilateral decrease in frontal activity when performing a visual search task. This result demonstrates for the first time that premotor regions within the frontal lobe and rPPC are not only necessary to carry out a visual search task, but that they work together to bring about normal function.
The Churl's Wagon  [PDF]
Andres Kuperjanov
Folklore : Electronic Journal of Folklore , 2010,
Abstract: Suur Vanker (‘the Great Wain’ in Estonian, the Big Dipper) is a commonly known constellation in Estonia. In addition to Suur Vanker, the astronym Hunt H rja k rval ‘Wolf beside the Ox’ is one of the oldest written recordings of ethno-astronomic designations. The tale about farmer Peedu and his wagon, formalised and elaborated by Jakob Hurt based on his collections, has been printed in school textbooks since the issuing of Mihkel Kampmann’s reading book, Kooli lugemise raamat at the beginning of the previous century. Thus, the story is widely known and has been simultaneously considered an Estonian astral myth.
Analytical modelling cargoes displacement in wagon and tension in fastening
Transport Problems : an International Scientific Journal , 2008,
Abstract: The article deals with the conclusions of analytical modeling cargoes displacement relative wagon and tension in fastening on exposure to spatial system of forces.
Mathematical modelling of fastening with cargoes displacement transverse to wagon
Transport Problems : an International Scientific Journal , 2008,
Abstract: The article has considered the situation when the mechanical system “wagon – fastening – cargo“ is influenced by transverse and vertical forces. It has given the results of mathematical modeling construction of cargo in wagon running on the curve section of track. It has stated the conclusion of analytical formula of cargo displacement transverse to wagon and tension in fastening from exposure to transverse and vertical forces.
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