Y-axis Orientation Research Articles

Influence of collision energy on the stereodynamics of the H+CH+→C++H2 reaction

The reactive cross section and stereodynamics at selected collision energies for the H(2S)+CH+(X1Σ+)→C+(2P)+H2(X1Σg+) reaction on a globally smooth ab initio potential surface of the 2A' state are calculated in detail by the quasi-classical trajectory(QCT) method. The calculated cross section decreases with the increase of the collision energy, which is found to be in overall good agreement with the previous time-dependent quantum results in the high collision energy regime (Ec>20 meV). The discrepancy between the QCT and previous quantum cross section below 20 meV can be attributed to the limitations of the classical trajectory method, because the QCT method cannot handle the effect of zero point energy. In general, QCT results show qualitative agreement with the quantum results, which confirmsthe validity of the QCT method. The research shows that the product rotational angular momentum vector is aligned and oriented. The alignment of the product rotational angular momentum vector j' depends very sensitively on the collision energy. With the increase of the collision energy, the alignment effect recedesin the low collision energy region (1500 meV), while it is enhanced in the high collision energy region (500-1000 meV). Moreover, the k-k'-j' distributions tend to be asymmetric with respect to the k-k' scattering plane (or about φr=180°), with two peaks appearing at φr=90° and φr=270°, respectively. This indicates that the product rotational angular momentum is not only in the Y-axis direction but also along the positive Y-axis direction. The peak intensity decreases with the collision energy increasing from 1 meV to 100 meV, while it increases with collision energy increasing from 100 meV to 1000 meV. Therefore the Y-axis orientation effect turns weak with the enhancement of the collision energy in the low energy region, while it becomes strong in the high energy region. In addition, the polarization dependent differential cross sections (PDDCSs) (2π/σ)(dσ00/dωt) and (2π/σ)(dσ20/dωt) are calculated. PDDCS (2π/σ)(dσ00/dωt) results indicate that the products have almost symmetrically scattered forward and backward, and the intensity of the scattering increases with the increase of the collision energy. The PDDCS (2π/σ)(dσ20/dωt) shows that the alignment effect of the rotational angular momentum of the products is stronger at the terminal of the scattering angle than at the other directions.

Beam quality M2 factor matrix for non-circular symmetric laser beams

It is standard to use and to characterize the beam quality of a non-circular symmetrical beam on its x-axis and y-axis orientation. However, we knew that the values of and are inconsistent if one selects a different coordinate system or measures beam quality with different experimental conditionals, even when analyzing the same beam. To overcome this, a new beam quality characterization method, the M2 factor matrix, is developed. It not only contains the beam quality terms, and , to characterize the beam quality along x-axis and y-axis orientation for the non-symmetric beam, but also introduces two additional cross terms, Mxy and Myx, which are used to characterize the location relationship between the principal axis of the test beam and coordinate system in experiment. Moreover, M2 factor matrix can be measured with a similar procedure to the traditional M2 factor whose measurement instructions are described in ISO11146 by adding some additional image and signal processing procedure. The measurement principle and method is present and the experiment system for beam quality M2 factor matrix is built to demonstrate the performance of M2 factor matrix with real experiments.

Evidence of light-dependent magnetic compass orientation in urodele amphibian larvae

Experiments were conducted to investigate whether larval palmate newts undertake orientation toward or away from the home shoreline (y-axis orientation) using the geomagnetic field to steer the most direct route, and if they accomplish this task through a light-dependent magnetoreception mechanism similar to that found in anuran tadpoles and adult newts. Larval palmate newts trained and then tested under full-spectrum light showed bimodal magnetic compass orientation that coincided with the magnetic direction of the trained y-axis. In contrast, larvae trained under long-wavelength (≥500nm) light and then tested under full-spectrum light displayed bimodal orientation perpendicular to the trained y-axis direction. These results offer evidence for the use of magnetic compass cues in orienting urodele amphibian larvae, and provide additional support for the light-dependent magnetoreception mechanism since they are in complete agreement with earlier studies showing that the observed 90° shift in the direction of magnetic compass orientation under long-wavelength light (≥500nm) is due to a direct effect of light on the underlying magnetoreception mechanism. This study is the first to provide evidence of a light-dependent magnetic compass in larval urodeles.

Y-axis orientation in the South American freshwater snail species Chilina patagonica (Gastropoda: Chilinidae)

Y-axis orientation, a movement perpendicular to the shore or coastline, enables aquatic animals to stay in a preferred zone in generally unstable habitats. Such behaviour is a widespread phenomenon in many freshwater and intertidal animal taxa. In the present study, an arena approach was used to test the orientation response of pulmonate freshwater snails. Using this experimental design, Y-axis orientation was shown for the first time in a freshwater snail species, the riverine Chilina patagonica. Some cues, potentially mediating Y-axis orientation, appeared to play no role in the shown orientation behaviour, such as chemical, gravity and humidity cues or a sun compass. Magnetic cues, however, could not be excluded. Since no significant differences in orientation were detected between different size classes in C. patagonica, orientation behaviour may not vary substantially throughout the snail's life history. In contrast to C. patagonica, no consistent orientation response was seen in the related lacustrine species Chilina llanquihuensis. The adaptation of C. patagonica to exhibit orientation along the Y-axis may be driven by the avoidance of high velocities in deeper water.

Use of a light-dependent magnetic compass for y-axis orientation in European common frog (Rana temporaria) tadpoles

We provide evidence for the use of a magnetic compass for y-axis orientation (i.e., orientation along the shore-deep water axis) by tadpoles of the European common frog (Rana temporaria). Furthermore, our study provides evidence for a wavelength-dependent effect of light on magnetic compass orientation in amphibians. Tadpoles trained and then tested under full-spectrum light displayed magnetic compass orientation that coincided with the trained shore-deep water axes of their training tanks. Conversely, tadpoles trained under long-wavelength (≥500nm) light and tested under full-spectrum light, and tadpoles trained under full-spectrum light and tested under long-wavelength (≥500nm) light, exhibited a 90° shift in magnetic compass orientation relative to the trained y-axis direction. Our results are consistent with earlier studies showing that the observed 90° shift in the direction of magnetic compass orientation under long-wavelength (≥500nm) light is due to a direct effect of light on the underlying magnetoreception mechanism. These findings also show that wavelength-dependent effects of light do not compromise the function of the magnetic compass under a wide range of natural lighting conditions, presumably due to a large asymmetry in the relatively sensitivity of antagonistic short- and long-wavelength inputs to the light-dependent magnetic compass.

Hierarchy of sun, beach slope, and landmarks as cues for Y-axis orientation of the supratidal amphipod Talorchestia longicornis (Say)

The semi-terrestrial amphipod Talorchestia longicornis (Say) undergoes Y-axis orientation and has a hierarchy among orientation cues. A previous study found that they used sun compass orientation and moved in the onshore direction of the home beach in both air and water. The present study determined whether this species could also use local landmarks and beach slope as orientation cues. They oriented upslope in simulated darkness in the laboratory on both dry and wet sand with threshold slopes of 2° and 4°, respectively. When tested outside in an arena in air on wet sand, they were disoriented when sun, slope, and landmarks were absent as cues. If presented with single cues, they moved upslope, toward landmarks and in the up-beach direction of the home beach during sun compass orientation. Using paired cues, sun was dominant over slope and landmarks, while slope was dominant over landmarks. In the presence of all three cues, amphipods displayed sun compass orientation in all test combinations except when slope and landmarks were paired together against the sun, which evoked a bimodal response. Thus, the hierarchy of cues for up-beach movement of T. longicornis during Y-axis orientation is the sun, then the slope, and finally the landmarks.

Force feedback pushing scheme for micromanipulation applications

Pushing micro-objects using point contact provides more flexibility and less complexity compared to pick and place operation. Due to the fact that in micro-world surface forces are much more dominant than inertial forces and these forces are distributed unevenly, pushing through the center of mass of the micro-object may not yield a pure translational motion. In order to translate a micro-object, the line of pushing should pass through the center of friction. In this paper, a semi-autonomous scheme based on hybrid vision/force feedback procedure is proposed to push micro-objects with human assistance using a custom built tele-micromanipulation setup to achieve translational motion. In the semi-autonomous pushing process, velocity controlled pushing with force feedback is realized along x-axis by the human operator while y-axis orientation is undertaken automatically using visual feedback. In this way the desired line of pushing for the micro-object is controlled to pass through the varying center of friction. Experimental results are shown to prove nano-Newton range force sensing, scaled bilateral teleoperation with force feedback and pushing operation.

Use of a magnetic compass for Y-axis orientation in premetamorphic newts (Triturus boscai)

Experiments were carried out to investigate whether premetamorphic larvae of Bosca’s newt (Triturus boscai) are capable of using the geomagnetic field for Y-axis orientation (i.e., orientation toward and away from shore). Larvae were trained outdoor in two different training configurations, using one training tank aligned along the magnetic north–south axis, with shore facing north, and another training tank positioned with its length along the east–west axis, with shore located west. After training, premetamorphic newts were tested in an outdoor circular arena surrounded by a pair of orthogonally aligned cube-surface coils used to alter the alignment of the Earth’s magnetic field. Each newt was tested only once, in one of four magnetic field alignments: ambient magnetic field (i.e., magnetic north at North), and three altered fields (magnetic north rotated to East, West, South). Distributions of magnetic bearings from tested larvae indicated that they oriented bimodally along the magnetic direction of the trained Y-axis. These findings demonstrate that T. boscai larvae are sensitive to the geomagnetic field and can use it for orienting along a learned Y-axis. This study is the first to provide evidence of Y-axis orientation, accomplished by a magnetic compass, in larval urodeles.

Use of a Magnetic Compass for Y-Axis Orientation in Larval Bullfrogs, Rana catesbeiana

The use of a magnetic compass plays a significant role in the daily and seasonal movements of numerous organisms; however among amphibians, magnetic compass orientation has been convincingly demonstrated only in eastern red-spotted newts, Notophthalmus viridescens, with some indirect evidence coming from several species of bufonid toads. In this study, larval bullfrogs, Rana catesbeiana, were trained in outdoor tanks with two different Y-axis (shore/deep water) directions and then tested in an indoor arena in one of four symmetrical alignments of an earth-strength magnetic field. The tadpoles oriented bimodally along the correct magnetic direction of the Y-axis experienced during training, demonstrating that this anuran species is able to learn and orient along the Y-axis by sensing the geomagnetic field.

Magnetic Compass Orientation in the Eastern Red-Spotted Newt,Notophthalmus viridescens: Rapid Acquisition of the Shoreward Axis

Abstract Orientation toward and away from shore (y-axis orientation) plays an important role in the daily and seasonal movements of amphibians. A variety of studies have shown that amphibians use both celestial cues and the geomagnetic field for y-axis orientation. However, few studies have addressed how quickly amphibians are able to learn the direction of a new shore. In the present laboratory-based experiments, we show that the Eastern Red-Spotted Newt, Notophthalmus viridescens, is able to learn the direction of the y-axis with respect to the geomagnetic field within 12–16 h. In conjunction with previous findings, our results suggest that the geomagnetic field is an important and readily used cue for orientation in amphibians.

Homing Behavior of the Lizard Sceloporus jarrovi

The homing ability of Sceloporus jarrovi was studied in southeastern Arizona during the summers of 1978-1980. One hundred eight lizards were displaced distances ranging from 50-200 m. The homing success of males and females was similar. Adults returned home from all displacement distances, while juveniles homed poorly at distances greater than 50 m. Juvenile S. jarrovi may be poor at homing because they are unfamiliar with areas greater than 50 m from their homes, and/or because they lack sufficient attachment to their home ranges due to their young age (2 months in this study). Among adults, one year old lizards returned home in significantly fewer numbers than older animals. Their lower homing success may be attributable to a weaker attachment to a home range since these lizards are often subor- dinates in the population. For one year old lizards, as for juveniles, the costs of homing may simply outweigh the benefits of establishing a new home range. There was no significant difference in homing success between lizards displaced in opposite directions. This indicates that lizards were not moving in stereotyped compass directions after release. Once lizards returned home, they remained in the same area, even in subsequent years. It is unlikely that S. jarrovi uses any of the following homing mechanisms: Y-axis orientation, use of sensory cues obtained during the displacement journey, or geotaxis.

Sun compass orientation of the northern cricket frog, Acris crepitans

Summary When released in water at the centre of a circular pen 50 ft in diameter, northern cricket frogs ( Acris crepitans ) from shores of natural bodies of water oriented on a compass course (Y-axis) that bisected the home shore at rightangles. Frogs taken to the test pen in closed containers responded similarly to those moved in view of the sky, and Y-axis orientation was unaffected in individuals displaced 115 miles east in light-tight containers. Specimens from opposite shores oriented to their respective Y-axis, even when released simultaneously. When a large number of individuals was collected from one segment of shore line and held in darkness for periodic release during a 24-hr period, orientation persisted under the sun, moon, and/or stars. Cricket frogs held in darkness at a constant temperature for periods of 30 hr and up to 7 days exhibited a decline in accuracy of Y-axis orientation that culminated in a random pattern after 7 days. Apparently differences in phase synchronization between the frogs timing mechanism and local time were responsible for the failure to orient. Orientation was reestablished to the original Y-axis by exposing ‘dephased’ specimens to the normal light-dark regime or to daily temperature and humidity fluctuations. A photo-period of normal duration, but administered 6 hr early (or late) relative to local time, reestablished orientation, but on a Y-axis 90° to the left (or right) of the original. A daily exposure to 10 min indirect light was sufficient to reestablish orientation in 8 days. A learned shore position, view of a useful celestial cue, and a timing mechanism phased to local time are necessary for Y-axis type of orientation. The demonstrated use of several types of temporal cues in the cricket frog suggests that alternative sources of information from several environmental components may be employed in nature, depending upon circumstance and availability. Y-axis type of orientation is a complex mechanism and appears to be a basic behavioural characteristic shared by most or all anurans

Correction of the compass in iron ships

Experiments were conducted to investigate whether larval palmate newts undertake orientation toward or away from the home shoreline (y-axis orientation) using the geomagnetic field to steer the most direct route, and if they accomplish this task through a light-dependent magnetoreception mechanism similar to that found in anuran tadpoles and adult newts. Larval palmate newts trained and then tested under full-spectrum light showed bimodal magnetic compass orientation that coincided with the magnetic direction of the trained y-axis. In contrast, larvae trained under long-wavelength (≥500 nm) light and then tested under full-spectrum light displayed bimodal orientation perpendicular to the trained y-axis direction. These results offer evidence for the use of magnetic compass cues in orienting urodele amphibian larvae, and provide additional support for the light-dependent magnetoreception mechanism since they are in complete agreement with earlier studies showing that the observed 90° shift in the direction of magnetic compass orientation under long-wavelength light (≥500 nm) is due to a direct effect of light on the underlying magnetoreception mechanism. This study is the first to provide evidence of a light-dependent magnetic compass in larval urodeles.