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Geometric morphometric studies of dolphins have traditionally concentrated on the skull, while the mandible and its modularity have been little explored. We investigated the mandible variability and modularity in three strictly related Mediterranean dolphins:Stenella coeruleoalba,Delphinus delphisandTursiops truncatus. The aims were to describe the interspecific differences in the size and shape of the mandible as a whole, and of its structural modules, and to detect the influence of adaptive pressures on trait variation. Data were collected on 96 specimens from the Mediterranean Sea. Eight and 10 two-dimensional landmarks were recorded respectively in the lateral and medial sides of the mandible. After General Procrustes Analysis (GPA) transformation, measurement error, sexual dimorphism and ontogenetic allometry were first investigated to allow further pooling of samples. Univariate analysis of variance (ANOVA) of centroid size was used to evaluate size differences among the species; multivariate ordination, classification and clustering methods were used to investigate interspecific variation of shape variables. Different subsets of landmarks representing distinct mandibular subunits were tested for modular integration through the RV coefficient; two-block partial least squares statistics was used to explore the patterns of covariation between modules. Size and shape differences in the whole mandible of the three species evidenced a clear morphological divergence ofTursiops truncatusand a close similarity ofStenella coeruleoalbaandDelphinus delphis. The analysis of modularity identified the corpus and the ramus, with its internal foramen, as distinct modules. The corpus and ramus patterns of variation could discriminate betweenT. truncatusvs. the other two species. The mandibular foramen was the only trait able to discriminate each species, and the corresponding shape differences were related to selective pressures toward the differentiation of communication patterns. [ABSTRACT FROM AUTHOR]

Regeneration of the second antennae of Asellus aquaticus is described here following amputations along the antennal flagellum. The process involves the frequent resorption (loss of the distalmost joint remained on the amputated antenna) and the regular apicalization of the new terminal article. In the distal part of the flagellum, resorption occurs only when less than 70% of the original article length is left. For amputations performed in the proximal meristematic region, where new articles are normally produced, the new terminal article may also divide, sometimes producing articles with abnormal setal pattern; instead, articles that would normally divide may fail to do so if they are the nearest proximal neighbour of the new terminal article. Outcome of the increased production of new articles from the meristematic region is a regenerated antenna with a number of flagellomeres close to that shown by the undamaged controlateral one. Similarities and differences in respect to the processes occurring after amputation in the antennal peduncle, as well as in other arthropod limbs, are discussed. These differences may help with understanding general properties of the regeneration process, such as the distinction between epimorphosis and morphallaxis and the relationship between normal development and regeneration. [ABSTRACT FROM AUTHOR]

The design of tracking controllers for induction motors is usually developedby neglecting the presence of power-supply devices, such as inverters, andmeasurement apparatuses, e.g., encoders. However, these components representunmodeled dynamics that are present during the real operating conditions ofthe induction motor. Since the development of a numerical simulation studyrepresents a low-cost, safe, and fast test to validate the design of trackingcontrol schemes, the need arises to build a computer model of the overallsystem (i.e., motor, power supply, measurement devices, and tracking controller)as realistic as possible. In this context, the paper describes a computermodel for simulation of an induction motor under a tracking control schemeincluding many real-world effects; namely, encoder's quantization, currentsensors' noise, stator current dynamics, presence of a current-controlledvoltage-source inverter within a stator current regulator loop, flux observerdynamics, saturation of the control signal, and discrete-time implementationof the control algorithm. The developed computer model is finally used ina case study and the simulation results obtained for an induction motor drivinga single-link robotic arm under an H [sub infin;] tracking controlscheme are reported. [ABSTRACT FROM AUTHOR]

Beam wandering (random lateral displacement) enhancement of thin beams by a double passage through turbulence is theoretically and experimentally investigated. A relationship is found between the random lateral displacements of double passage and single passage, in the case of homogeneous turbulence. Results of laboratory measurements are presented and suggestions for practical use given. [ABSTRACT FROM AUTHOR]