Conflict outcome in male green swordtail fish dyads (Xiphophorus helleri): Interaction of body size, prior dominance/subordination experience and prior residency

The relative contribution of asymmetries in prior experience, size, and prior residency to the determination of dyadic dominance between unacquainted individuals was examined using pairs of green swordtail fish, Xiphophorus helleri. Four types of encounters were staged between an intruder and a smaller resident: (1) both had experienced prior victory; (2) both had experienced prior defeat; (3) the intruder had experienced prior victory and the resident prior defeat; and (4) the intruder had experienced prior defeat and the resident prior victory. In a fifth condition in which two intruders met, one was a prior subordinate and the other a prior dominant smaller in size than its opponent. In all these encounters, the superiority in lateral surface of one fish varied between 0 to 30% over that of its opponent. Results showed that (1) when size differences between contestants were within the range of 0-10% and there was an asymmetry in prior social experience, conflicts were essentially resolved according to prior experience with prior winners systematically defeating prior losers; (2) prior residency of 3 hours was an advantage only when both opponents had experienced prior defeat before meeting and when size asymmetries were small (e.g. <20%). It was not an advantage between prior winners or between a prior winner and a prior loser; (3) when large size asymmetries existed (e.g. 20-30%), size uniquely determined dominance outcome and nullified other advantages or disadvantages due to prior social experience and prior residency; and (4) at intermediate levels of size asymmetries (e.g. 10-20%), size partially cancelled any advantage due to a prior victory, and gradually beacme the most important factor in accounting for victories

Outcome of dyadic conflict in male green swordtail fish, Xiphophorus helleri: effects of body size and prior dominance

The relative contribution of prior experience and of size asymmetries to the determination of dyadic dominance between unfamiliar individuals was examined using pairs of green swordtail fish, Xiphophorus helleri. Three experiments were conducted to assess the extent to which superiority in size could override potential handicaps resulting from prior experience. These results indicated that prior experience accounted for dyadic dominance when the size advantage of a previously subordinate over a previously dominant opponent was less than 25 mm2. However, as the lateral surface of the subordinate fish increased, neither previous experience nor size differences clearly accounted for the outcome of dyadic conflict. Even when the size advantage of subordinate opponents was in the 126-150 mm2 range, size differences did not adequately explain the outcome. In conflicts between large previously subordinate and smaller dominant fish, there was evidence for an inverse linear relation between the effects of size and the likelihood of establishing dyadic dominance. In general, males with prior experience as subordinates had to be at least 40% larger than a previously dominant fish to win a significant proportion of conflicts. These results indicate that prior agonistic experience and body size effects can be additive when at the advantage of one opponent. These factors can also cancel each other out when in opposition, at least when size differences are not extreme. The results also confirm the main effect of both factors as well as their interaction in the determination of conflict outcomes for X. helleri

Investigation of test methods, material properties, and processes for solar cell encapsulants

The development of pottant compounds is emphasized. Formulation of the butyl acrylate syrup/casting pottant was completed. The formulation contains an ultraviolet stabilizer system and may be cured with an initiator that, unlike former selections, presents no shipping of handling hazards to the user. The catalyzed syrup is stable at room temperature and has a pot life of at least eight hours. The formulation of the ethylene/methyl acrylate lamination pottant was also completed. This compound is the alternative pottant to EVA and is similarly produced as an extruded sheet that is wound into rolls. This resin is inherently nonblocking

Automatic testing of organic strain gauge tactile sensors.

Human-Robot Interaction is a developing field of science, that is posed to augment everything we do in life. Skin sensors that can detect touch, temperature, distance, and other physical interaction parameters at the human-robot interface are very important to enhancing the collaboration between humans and machines. As such, these sensors must be efficiently tested and characterized to give accurate feedback from the sensor to the robot. The objective of this work is to create a diversified software testing suite that removes as much human intervention as possible. The tests and methodology discussed here provide multiple realistic scenarios that the sensors undergo during repeated experiments. This capability allows for easy repeatable tests without interference from the test engineer, increasing productivity and efficiency. The foundation of this work has two main pieces: force feedback control to drive the test actuator, and computer vision functionality to guide alignment of the test actuator and sensors arranged in a 2D array. The software running automated tests was also made compatible with the testbench hardware via LabVIEW programs. The program uses set coordinates to complete a raster scan of the SkinCell that locates individual sensors. Tests are then applied at each sensor using a force controller. The force feedback control system uses a Proportional Integral Derivative (PID) controller that reads in force readings from a load cell to correct itself or follow a desired trajectory. The motion of the force actuator was compared to that of the projected trajectory to test for accuracy and time delay. The proposed motor control allows for dynamic force to stimulate the sensors giving a more realistic test then a stable force. A top facing camera was introduced to take in the starting position of a SkinCell before testing. Then, computer vision algorithms were proposed to extract the location of the cell and individual sensors before generating a coordinate plane. This allows for the engineer to skip over manual alignment of the sensors, saving more time and providing more accurate destinations. Finally, the testbench was applied to numerous sensors developed by the research team at the Louisville Automation and Robotics Research Institute (LARRI) for testing and data analysis. Force loads are applied to the individual sensors while recording response. Afterwards, postprocessing of the data was conducted to compare responses within the SkinCell as well as to other sensors manufactured using different methods

Variability of Temperature and Salinity in the Middle Atlantic Bight and Gulf of Maine

Monitoring of the waters of the Middle Atlantic Bight and Gulf of Maine has been conducted by the MARMAP Ships of Opportunity Program since the early 1970's. Presented in this atlas are portrayals of the temporal and spatial patterns of surface and bottom temperature and surface salinity for these areas during the period 1978-1990. These patterns are shown in the form of time-space diagrams for single-year and multiyear (base period) time frames. Each base period figure shows thirteen-year (1978-1990) mean conditions, sample variance in the form of standard deviations of the measured values, and data locations. Each single-year figure displays annual conditions, sampling locations, and departures of annual conditions from the thirteen-year means, expressed as algebraic anomalies and standardized anomalies. (PDF file contains 112 pages.

Relation between dominance rank, prior agonistic intensity and subsequent aggressive levels in winners and losers of dyads of male Green swordtail fish (Xiphophorus helleri)

Aggressive scores obtained in a mirror test 1h before an encounter were found to be a good predictor of victory in male Xiphophorus dyads showing less than 5% size differences. Out of 36 dyad members showing higher aggressive scores at pre-test, 28 obtained victory in the subsequent encounter. It was found that future winners were more aggressive than future losers to their own image in mirror tests before their encounter. Initial individual aggressive levels in mirror tests were also found to be a function of the rank the individuals occupied in their home hierarchies. The higher the rank, the higher was the individual aggressive level as measured by mirror pre-tests, as well as by post-tests. This relationship applied to future winners, as well as to future losers. The level of aggression reached during agonistic encounter was not a function of the social ranks the opponents occupied in their home hierarchies. Males in dyads composed of two omegas fought as fiercely as males in dyads of two alphas or two betas. No significant relationship was noted between the initial individual aggressive scores at mirror pre-test and the levels of aggression reached during encounters. We found in winners the existence of a significant correlation between the aggressive level they reached during agonistic encounter and a subsequent increase in aggressive levels at mirror tests 1h and 24h after victory. The more intense the agonistic encounter, the more important the subsequent increase in aggressive level in winners; an increase which was still detectable 24h after victory. However, prior alpha winners were apparently not as sensitive as prior betas and prior omegas to the aggressive level reached during the encounter since their mirror scores obtained after victory did not change when compared to their baseline at pre-test. After defeat, losers did not show any significant change in aggressive scores in mirror tests. Moreover, it was found that encounters in which a 1h resident met an intruder were in general less aggressive than encounters between two intruders. Experiential effects are discussed as instances of learning and generalisation

DES DIFFÉRENCES LIÉES AU SEXE DANS LES STRATÉGIES DE RÉPARTITION SPATIALE CHEZ DES POISSONS PORTE-ÉPÉE (XIPHOPHORUS HELLERi) MAINTENUS EN CAPTIVITÉ

The swordtail fish is a species particularly abundant in fresh water of Mexico and Central America. It is an ovoviviparous species, not really territorial which shows nip&#64979;right order. In this research, significant differences of spatial distribution have been found according to the position in the nip&#64979;right order and according to the sex of the fish. These differences bind with two external variables: the presence of sexual partners and the space available for the fish. The dominating males prefer a space partition allowing access to the females more than a compartment allowing access to more space in volume. They also chase their subordinates in the contiguous compartment of the aquarium. Females swordtails prefer the bigger compartment independently of the presence of conspecific males. These results are discussed in the light of reproductive strategies particular to each sex