Courtship behavior, communication, and copulation in Tigrosa annexa

The evolution of multimodal communication, where signalers use multiple signal components in multiple sensory modalities, has become the subject of investigation by many researchers. Signaling puts males at risk of predation, so why do males of some species evolve extra signals that may increase this risk? In some wolf spider species, males incorporate many visual and vibrational signals into a display that they use to attract a female for mating. Female spiders are often aggressive toward courting males and so the male display also functions to decrease the odds of cannibalism. Female wandering spiders deposit silk containing pheromones that communicate their condition to the males. Here, we investigate the complex mating displays and male-female interactions involved in reproduction in a locally-abundant wolf spider, Tigrosa annexa. We describe the male courtship display and observe male mating success and frequency of cannibalism. Males were exposed to the pheromone-laden silk of females and their courtship was recorded in the absence of a female. We also conducted mating trials in which a male and a female interacted for 30 minutes to measure rates of copulation and cannibalism. We found that males readily initiated courtship when exposed to cues from a female in a variety of conditions, and that females rarely engaged in cannibalism, despite our manipulation of their diet. The results of these experiments suggest that cannibalism by female T. annexa spiders may not have been a strong evolutionary force on male courtship display

Closer Than You Think: The Implications of the Third Offset Strategy for the U.S. Army

The Defense Innovation Initiative (DII), begun in November 2014 by former Secretary of Defense Chuck Hagel, is intended to ensure U.S. military superiority throughout the 21st century. The DII seeks broad-based innovation across the spectrum of concepts, research and development, capabilities, leader development, wargaming, and business practices. An essential component of the DII is the Third Offset Strategy—a plan for overcoming (offsetting) adversary parity or advantage, reduced military force structure, and declining technological superiority in an era of great power competition. This study explored the implications for the Army of Third Offset innovations and breakthrough capabilities for the operating environment of 2035-2050. It focused less on debating the merits or feasibility of individual technologies and more on understanding the implications—the second and third order effects on the Army that must be anticipated ahead of the breakthrough.https://press.armywarcollege.edu/monographs/1403/thumbnail.jp

Airborne mapping of complex obstacles using 2D Splinegon

This paper describes a recently proposed algorithm in mapping the unknown obstacle in a stationary environment where the obstacles are represented as curved in nature. The focus is to achieve a guaranteed performance of sensor based navigation and mapping. The guaranteed performance is quantified by explicit bounds of the position estimate of an autonomous aerial vehicle using an extended Kalman filter and to track the obstacle so as to extract the map of the obstacle. This Dubins path planning algorithm is used to provide a flyable and safe path to the vehicle to fly from one location to another. This description takes into account the fact that the vehicle is made to fly around the obstacle and hence will map the shape of the obstacle using the 2D-Splinegon technique. This splinegon technique, the most efficient and a robust way to estimate the boundary of a curved nature obstacles, can provide mathematically provable performance guarantees that are achievable in practice