Alternative Mating Tactics and Their Impact on Survival in Adult Male Alpine Ibex (Capra ibex ibex)

Adult male Alpine ibex (Capra ibex ibex) have been shown to exhibit unusually high survival to relatively advanced ages (>10 years), leading to speculation that males may engage in an energetically conservative reproductive strategy that increases survival. We investigated the extent to which the adoption of alternative mating tactics contributes to the extraordinary survival of adult males in this species. Because basic information on the mating system of Alpine ibex is scarce, we 1st characterized the temporal and spatial distribution of receptive females. Our observations during 3 consecutive rutting seasons revealed 2 alternative mating tactics. Apparently dominant males monopolized individual receptive females by following and defending them, a tactic known as tending. In contrast, apparently subordinate males tried to achieve temporary access to tended females when the latter started to run, a tactic referred to as coursing. In total, 24 copulations were observed, of which 20 (83.3%) were the result of tending and 4 were the result of coursing. The adoption of the 2 tactics was strongly age-dependent; older males (9-12 years) engaged primarily in tending, whereas younger males (2-6 years) engaged mainly in coursing. Males adopting the coursing tactic spent more time in low-cost and less time in high-cost behaviors than males adopting the tending tactic. Time-budget comparisons with another ungulate species suggested that although tending is a relatively costly tactic, coursing is a low-cost tactic that may contribute to the exceptional adult survival in male Alpine ibe

Social dominance and conflict reduction in rutting male Alpine ibex, Capra ibex

In polygynous ungulates, male mortality is thought to be linked to high-energy expenditures during the rut. However, Alpine ibex (Capra ibex) adult males show an unusually high survival during this time. Male Alpine ibex live in social groups and thus, we assumed that they might reduce energy-intensive interactions during the rut by establishing, early on, strict dominance hierarchies. To evaluate this hypothesis, we studied social interactions and mating behavior in a population of Alpine ibex in the Swiss Alps. In accordance with our prediction, and in contrast to other polygynous ungulates, male Alpine ibex decreased time spent in agonistic interactions and the number of fights during the rut compared with the prerut, irrespective of their age. Changes between access-holding males always occurred without foregoing fights and were entirely based on preestablished and stable dominance relationships. Therefore, dominant males always gained and held access to receptive females and thus managed to adopt the tending tactic. Subordinate males either left the consort pair or they adopted the coursing tactic in order to achieve temporary access to estrous females. They behaved extremely reluctantly toward dominants, as they never made use of overt aggression to challenge them or to create actively transient mating opportunities. Our study supports the hypothesis that costly intramale interactions are reduced during the mating season in Alpine ibex by the adherence to preestablished and stable dominance relationships. Accordingly, male Alpine ibex appear to be able to cut down on energy expenditures, which in turn, likely contributes to their superior surviva

Many-to-Many Graph Matching: a Continuous Relaxation Approach

Graphs provide an efficient tool for object representation in various computer vision applications. Once graph-based representations are constructed, an important question is how to compare graphs. This problem is often formulated as a graph matching problem where one seeks a mapping between vertices of two graphs which optimally aligns their structure. In the classical formulation of graph matching, only one-to-one correspondences between vertices are considered. However, in many applications, graphs cannot be matched perfectly and it is more interesting to consider many-to-many correspondences where clusters of vertices in one graph are matched to clusters of vertices in the other graph. In this paper, we formulate the many-to-many graph matching problem as a discrete optimization problem and propose an approximate algorithm based on a continuous relaxation of the combinatorial problem. We compare our method with other existing methods on several benchmark computer vision datasets.Comment: 1

Generic Spacecraft Model for Real-Time Simulation

Generic Spacecraft is the name of an evolving library of software that provides for simulation of a generic spacecraft that can orbit the Earth and land on the Moon (and, eventually, on Mars). This library is incorporated into the Langley Standard Realtime Simulation in C++ (LaSRS++) software framework. The generic-spacecraft simulation serves as a test bed for modeling spacecraft dynamics, propulsion, control systems, guidance, and displays. The Generic Spacecraft library supplements the LaSRS++ framework with an interface that facilitates the connection of new models into the LaSRS++ simulation by eliminating what would otherwise be the necessity of writing additional C++ classes to record data from the models and code to display values on graphical user interfaces (GUIs): The library includes routines for integrating new models into the LaSRS++ framework, identifying model inputs and outputs with full descriptions and units identified, recording data, and automatically generating graphical user interfaces (GUIs). The library is designed to be used in a manner similar to that of LaSRS++ software components for simulating vehicles other than the generic spacecraft. The user specifies (1) a spacecraft and individual models to be constructed and (2) connections between individual model inputs and outputs

Causal trajectories description of atom diffraction by surfaces

9 pages, 7 figures -- PACS numbers: 79.20.Rf, 03.65.Sq, 03.65.BzThe method of quantum trajectories proposed by de Broglie and Bohm is applied to the study of atom diffraction by surfaces. As an example, a realistic model for the scattering of He off corrugated Cu is considered. In this way, the final angular distribution of trajectories is obtained by box-counting, which is in excellent agreement with the results calculated by standard S-matrix methods of scattering theory. More interestingly, the accumulation of quantum trajectories at the different diffraction peaks is explained in terms of the corresponding quantum potential. This non-local potential "guides" the trajectories causing a transition from a distribution near the surface, which reproduces its shape, to the final diffraction pattern observed in the asymptotic region, far from the diffracting object. These two regimes are homologous to the Fresnel and Fraunhofer regions described in undulatory optics. Finally, the turning points of the quantum trajectories provide a better description of the surface electronic density than the corresponding classical ones, usually employed for this task.This work was supported by DGES (Spain) under contracts No PB95-71, PB95-425 and PB96-76. A.S. Sanz also acknowledges the Universidad Autónoma de Madrid for a doctoral grant.Peer reviewe

Single-shot carrier-envelope-phase measurement in ambient air

The ability to measure and control the carrier envelope phase (CEP) of few-cycle laser pulses is of paramount importance for both frequency metrology and attosecond science. Here, we present a phase meter relying on the CEP-dependent photocurrents induced by circularly polarized few-cycle pulses focused between electrodes in ambient air. The new device facilitates compact single-shot, CEP measurements under ambient conditions and promises CEP tagging at repetition rates orders of magnitude higher than most conventional CEP detection schemes as well as straightforward implementation at longer wavelengths