Zigzag Walking Research Articles

Measurement of the time required for termites to pass each other in tunnels of different curvatures

Subterranean termites construct complex tunnel networks for foraging. During travel in the tunnels, termites often encounter one another when passing in opposite directions. Such encounters are likely to affect the "movement efficiency," which is the time required for a termite to travel a certain distance in a tunnel. In this study, we explored how individual-individual encounters affect movement efficiency in tunnels by measuring the time (τ) taken by two termites to pass one another in tunnels of different curvatures. Artificial tunnels of 5 cm in length and variable widths (W) of 2, 3, or 4 mm were made. Tunnel distance (D) was 2, 3, 4, or 5 cm. When D had a higher value, curvature was lower. When W = 2, τ was significantly shorter in the tunnel with D = 5 than in tunnels of D = 2, 3, or 4, whereas τ was statistically the same for D = 2, 3 and 4. When W = 3, τ was shorter in the tunnel with D = 5 than for D = 3 and 4, while τ was longer in the tunnel with D = 2 than for D = 3 and 4. When W = 4, τ was longer in the tunnels with D = 2 and 3 than for D = 4 and 5. Based on these observations, 3 types of termite behavior were identified: biased walking, backward walking, and zigzag walking. We considered these results in relation to foraging efficiency.

Measurement of the Time Required for a Termite to Pass Through Tunnels with Different Curvatures

The subterranean termite, Reticulitermes speratus kyushuensis (Isoptera: Rhinotermitidae), excavate complex tunnel networks below the ground for foraging. The tunnels are either curved or meandering. In our previous study, results showed that termites passed smooth—rounded corners faster than they did around sharp corners. Smooth—rounded corners can be mathematically quantified by the curvature, representing the amount by which a geometric object deviates from a straight line. The present study explored how the time spent inside a tunnel changes in accordance with the degree of tunnel curvature. To do so, artificial tunnels with different curvatures were constructed in acryl substrates. Tunnels were 5 cm in length with widths of W — 2, 3, or 4 mm, and the distance between the two ends of the tunnel was D = 2, 3, 4, or 5 cm. A higher value of D signified a lower curvature. The time (τ) taken by a termite to pass through the tunnel was measured. In the case of W = 2 mm, the values of τ were statistically equal for D = 2, 3, or 4 cm, while τ for D = 5 cm was significantly lesser. In the case of W = 3, τ was statistically more for D = 2 and 3 cm than it was for D = 4 and 5 cm. For W = 4, τ was statistically equal for D = 2 and 3 cm, while τ for D = 4 cm was relatively shorter. Interestingly, the value of τ when D = 5 cm was statistically the same as D = 3 or 4 cm. These resulted from two types of termite behavior: biased walking and zigzag walking.

Plantas infestantes em lavouras de milho safrinha, sob diferentes manejos, no Médio Paranapanema

Um levantamento de plantas daninhas foi realizado em 20 lavouras de milho safrinha em 1997 e 40 em 1998 e 1999, depois da soja, na região do Médio Paranapanema-SP. O levantamento abrangeu os municípios de Assis, Campos Novos, Cândido Mota, Cruzália, Florínea, Maracaí, Palmital, Pedrinhas Paulista e Platina. No estádio de enchimento de grãos, as lavouras foram percorridas em ziguezague, a partir de quatro pontos de entrada, de maneira a representar a área total. As lavouras foram subdivididas de acordo com as condições de manejo das culturas: semeadura direta, semeadura convencional em solo preparado com grade e semeadura de milho safrinha na palha de soja cultivada no sistema convencional. Em cada lavoura foram cadastrados o nível de infestação e as espécies daninhas. Foram coletadas informações quanto ao manejo das plantas daninhas adotado nas lavouras, assim como sobre os herbicidas empregados. As espécies de plantas daninhas mais importantes foram Cenchrus echinatus, Bidens pilosa, Euphorbia heterophylla, Raphanus sativus, Digitaria horizontalis, Commelina benghalensis, Amaranthus sp., Achyrocline satureioides, Sinapis arvensis, Sida sp., Glycine max, Avena strigosa, Eleusina indica e Sorghum halepense. Houve acentuado aumento na infestação da espécie C. echinatus nas lavouras, a qual passou a constituir-se na principal espécie infestante. R. sativus também se tornou importante e apresentou grande incremento de 1997 a 1999. Na semeadura convencional houve predomínio de alta infestação, evidenciando desempenho inferior desse sistema em relação aos demais no controle de plantas daninhas. O controle químico mais utilizado foi a mistura atrazine + óleo vegetal + 2,4-D, seguido por atrazine + óleo e atrazine isolado. De modo geral, não se efetuou o controle das plantas daninhas em 22% das lavouras, as quais apresentaram as maiores porcentagens de infestação. O nível de infestação em função do tipo de controle foi variável de acordo com o ano agrícola.

携帯電話のメール機能を活用した歩行能力向上支援システムの開発

The purpose of this study was to develop a system for improving gait ability using the e-mail feature of a cellular phone, and to examine its effectiveness at a health class. This system was planned so that the participants could acquire a gait action known as core-stretch walking. One of the main features of this system is to send e-mails to provide guidance on the walking technique every day for 28 days. Forty-four participants in the class examined the effectiveness of this system, of whom 19 in the intervention group and 20 in the control group were analyzed. We compared the change in various measured parameters associated with gait ability (10m maximum walking time, number of steps in 10m maximum walking, 10m hurdle walking time, 10m zigzag walking time, timed up and go, and maximum step length) and with the subjects sense of walking in each group. As a result of this examination, we were able to recognize shortening of the measured figure associated with gait ability in the intervention group, as opposed to the control. Furthermore, the survey of attitude towards gait demonstrated that the intervention produced a clearer action of core-stretch walking. This system utilizing the e-mail feature of a cellular phone is suggested to have potential effectiveness for improvement of gait ability.

Coordination of flipflopping neural signals and head turning during pheromone-mediated walking in a male silkworm moth Bombyx mori

Male silkworm moths, Bombyx mori, move their heads side-to-side during zigzag walking toward a source of sex pheromone. High-speed video analysis revealed that changes in walking direction were synchronized with this head turning. Thus the direction of the walking is indicated by the direction of the head turning. Head turning was regulated by neck motor neurons which innervate the cervical ventral muscles and the ventral muscles through the second cervical nerve. To determine the role of the `flipflop' state transition in spike activity carried by descending interneurons from the brain to the thoracic ganglion, we recorded pheromonal responses simultaneously from flipflop descending interneurons and a single cervical ventral 1 neck motor neuron. The activity of the cervical ventral 1 neck motor neuron was synchronized to that of the flipflop descending interneurons. The cervical ventral 1 neck motor neuron was morphologically identified using confocal imaging. Our results demonstrate that the flipflop signals play an important role in instructing turning signals during the pheromone-mediated behavior in a male B. mori.

Coordination of wing motion and walking suggests common control of zigzag motor program in a male silkworm moth

The male silkworm moth, Bombyx mori, exhibits a zigzagging pattern as it walks upwind to pheromones. This species usually does not fly, but obvious wing-beating accompanies the pheromone-mediated walking. Males supported by a `sled', after having their legs removed, also moved upwind in a pheromone plume along zigzagging tracks, indicating that wing-generated thrust and torque result in locomotory paths similar to those observed from walking moths. Using a high-speed video system we investigated the correlation between the wing movements and zigzag walking. The wing ipsilateral to the direction of the turn showed a greater degree of retraction with respect to the contralateral wing. The timing of the wing retraction pattern was synchronized with changes of direction in the walking track. Coordination of wing movements and walking pattern was not dependent on visual feedback or sensory feedback generated from neck movements associated with turning. The results presented here, taken together with our previous studies of descending interneurons suggest that the coordination of wing movements with the walking pattern may result from the activity of a set of identified interneurons descending from the brain to the thoracic ganglia and/or may be coordinated by coupling of oscillating circuits for walking and wing beating.

Study on the stick-slip phenomenon on a cleaved surface of the Muscovite mica using an atomic force/lateral force microscope

Study was performed on the stick-slip phenomenon between the Muscovite mica and a cantilever tip. An atomic force/lateral force microscope with an optical lever deflection method was used, which detects the deflection and the torsion of the cantilever simultaneously. We observed the square-wave behavior across the scan direction, but the well-known sawtooth behavior due to the stick-slip motion of the tip along the scan direction. It is found that the square-wave and sawtooth behaviors were synchronized with each other. To explain these behaviors, we propose two-dimensional stick-slip model. In this model, the periodicity of the stick point is the same of that of the lattice structure of the mica surface, so that the tip apex takes a zig–zag walk along the scan.

The two-dimensional stick-slip phenomenon with atomic resolution

The authors investigated the atomic-scale stick-slip motion between muscovite mica and the Si3N4 tip apex of a cantilever using an atomic-force microscope combined with a lateral-force microscope (AFM/LFM). As a result, a square-wave behaviour of the cantilever motion was found across the scan direction, in addition to the well known sawtooth behavior along the scan direction. It was also found that the square-wave behavior was synchronized with the sawtooth behavior. To explain these phenomena, the authors proposed the two-dimensional stick-slip model, where the stick-points have the same periodicity as the lattice structure of the mica surface, so that the tip shows a zigzag walk along the scan. This new model seems to explain not only the one-dimensional line-scan profile, but also the contrast mechanism of the two-dimensional image.

格子状街路網地区における経路の選択ならびに探索に関する調査実験

A questionnaire survey about residents' path choice and experiments on wayfinding performance of the first-time visitors in residential areas organized by rectangular grid streets have been executed. Two types of path choice behavior, i.e., "boundary walking" and "zigzag walking", and also characteristics and situation of each walking type are identified. These results are discussed with respect to the Garbrecht's model of random walking and random paths.

Bilateral coding of sound direction in the CNS of the bushcricketTettigonia viridissima L. (Orthoptera, Tettigoniidae)

1. By means of simultaneous recordings with hook-electrodes the response behavior of a pair of homologous auditory interneurons on either side of the CNS of the bushcricketTettigonia viridissima L. was studied with particular emphasis on bilateral symmetry and directional coding. 2. In about 50% of the preparations the threshold curves of both interneurons were symmetrical, tested within a frequency range from 5 to 40 kHz (Fig. 4a). In the remaining cases significant bilateral asymmetries at frequencies above 20 kHz and/or below 12 kHz could be observed (Figs. 4 and 5). Therefore, in this bushcricket species symmetrical thresholds seem to be guaranteed only within a rather limited frequency band around 20 kHz. This frequency coincides with one (the higher) of the two spectral bands within the conspecific call (Fig. 2). 3. From recordings of unilaterally activated interneurons it can be inferred that the directional sensitivity of the single tympanic organ is as well tuned to this stimulus frequency of about 20 kHz. Maximal intensity differences of 15 to 20 dB between ipsiversus contralateral stimulation could be found (Fig. 3). Above and below this frequency the directionality of the ear was much lower. 4. This frequency dependence of directional hearing could be confirmed on the level of the CNS. Only at a stimulus frequency of about 20 kHz the directional curves of both interneurons were very pronounced (Fig. 10) with precisely encoding the lateralization of the sound source starting at about 10 dB above neuronal thresholds (Figs. 7, 8 and 9). 5. Though in single preparations the intensity-response curves of the two interneurons were notably different (Fig. 6), with respect to right versus left discrimination no auditory ‘handedness’ could be observed. 6. As some insects already orient to a single or a small number of stimuli, individual neuronal responses of the right versus the left interneuron were compared at different sound directions (Figs. 11 and 12). Surprisingly, with frontal stimulation the probability of ‘correct’ (symmetrical) responses was only 17% which abruptly increased as soon as the sound source became lateral. These results are discussed in terms of the zig-zag walk of the localizing insect.