Sequestration of host-plant-derived flavonoids by lycaenid butterflyPolyommatus icarus

Larvae of the lycaenid butterflyPolyommatus icarus were reared on inflorescences ofCoronilla varia andMedicago sativa, which are rich in flavonoids. Twelve different flavonoids (five compounds from the former and nine from the latter), including aglycones andO-glycosides of kaempferol, quercetin, and myricetin were isolated and identified by spectroscopic means. NMR and MS data for the new acylated glycoside kaempferol 3-O-6-(3-hydroxy-3-methylglutaroyl)--d-glucopyranoside are reported. Comparative HPLC analysis of the respective host plants and of larvae, pupae, and imagines ofP. icarus indicated selective uptake and accumulation of kaempferol vs. quercetin and myricetin derivatives. The latter were excreted largely unchanged through the feces. Irrespective of the larval host plant kaempferol 3-O-glucoside was found as the major flavonoid in larvae, pupae, and imagines ofP. icarus, accounting for approximately 83–92% of all soluble flavonoids in adult butterflies. Within the imagines, approximately 80% of all flavonoids are stored in the wings (especially in the orange submarginal lunules), whereas the remaining 20% reside in the bodies. Feeding experiments with artificial diet demonstrated that the insects are able to form kaempferol 3-O-glucoside by glucosylation of dietary kaempferol. Possible functions of the sequestered flavonoids, especially for mate recognition ofP. icarus, are discussed.     

Effect of predator odors on heart rate and metabolic rate of wapiti (Cervus elaphus canadensis)

We measured the heart rate (HR) and oxygen consumption ( ) of wapiti (Cervus elaphus canadensis) before, during, and after presentation of biologically irrelevant odors (pentane, thiophene, and a perfume), artificial predator odors (an ether extract of cougar feces, and PDT, a compound found in mustelid anal gland secretion), stale predator odors (dog feces and urine and fox urine, kept at ambient temperature for a few weeks), and fresh predator odors (wolf, coyote, and cougar feces and the odor of a dead coyote, kept frozen between collection and test). Overall, responses to odors were small compared to other stressful stimuli. Individual variability was high among scents and among wapiti, but two of the fresh predator odors (cougar and wolf feces) produced larger HR and responses than the other scents and were more often successful at producing responses. As a group, fresh predator odors produced larger tachycardias and elicited a larger number of significant HR responses than biologically irrelevant novel odors. although the two classes of odors did not differ in their effect on . Although several other studies have shown that ungulates have reduced feeding levels when their food is scented with predator odors, it is not clear if this is due to reduced palatability or antipredator behavior. This study is the first demonstration that a wild ungulate species reacted more strongly to predator odors than to other odors in a nonfeeding situation.     

Equivalence conditions for behaviors and the Kronecker canonical form

In this paper we explore equivalence conditions and invariants for behaviors given in kernel representations. In case the kernel representation is given in terms of a linear matrix pencil, the invariants for strict equivalence are given by the Kronecker canonical form which, in turn, we interpret in geometric control terms. If the behavior is given in a kernel representation by a higher order rectangular polynomial matrix, the natural equivalence concept is behavior equivalence. These notions are closely related to the Morse group that incorporates state space similarity transformations, state feedback, and output injection. A simple canonical form for behavioral equivalence is given that clearly exhibits the reachable and autonomous parts of the behavior. Using polynomial models we also present a unified approach to pencil equivalence that elucidates the close connections between classification problems from linear algebra, geometric control theory, and behavior theory. We also indicate how to derive the invariants under behavior equivalence from the Kronecker invariants.     

The student's construction of artistic truth in digital images

Images that clearly present a constructed physical truth, like digital images, remind us to question the reality factor of any image. Because many digital images appear to be photographic, or photographic-like, the medium forces artists to revisit what a photograph, and consequently a digital image, represents. In turn, this rethinking influences how students in computer art see reality and truth when they create digital imagery. Embracing this question, some digital artists have constructed visual narratives that appear photographic, yet lack the physical world referent that their images imply. Since the late 1980s and early 1990s, when this kind of construction became popular, many digital artists have grappled with how to identify the truth in their images. This study describes how some advanced digital art students resolved this conflict by defining their own artistic truths.     

Risky Social Networking Practices Among “Underage” Users: Lessons for Evidence‐Based Policy

European self‐regulation to ensure children's safety on social networking sites requires that providers ensure children are old enough to use the sites, aware of safety messages, empowered by privacy settings, discouraged from disclosing personal information, and supported by easy to use reporting mechanisms. This article assesses the regulatory framework with findings from a survey of over 25000 9‐ to 16‐year‐olds from 25 European countries. These reveal many underage children users, and many who lack the digital skills to use social networking sites safely. Despite concerns that children defy parental mediation, many comply with parental rules regarding social networking. The implications of the findings are related to policy decisions on lower age limits and self‐regulation of social networking sites.     

Avatar culture: cross-cultural evaluations of avatar facial expressions

Avatars are increasingly used to express our emotions in our online communications. Such avatars are used based on the assumption that avatar expressions are interpreted universally among all cultures. This paper investigated cross-cultural evaluations of avatar expressions designed by Japanese and Western designers. The goals of the study were: (1) to investigate cultural differences in avatar expression evaluation and apply findings from psychological studies of human facial expression recognition, (2) to identify expressions and design features that cause cultural differences in avatar facial expression interpretation. The results of our study confirmed that (1) there are cultural differences in interpreting avatars’ facial expressions, and the psychological theory that suggests physical proximity affects facial expression recognition accuracy is also applicable to avatar facial expressions, (2) positive expressions have wider cultural variance in interpretation than negative ones, (3) use of gestures and gesture marks may sometimes cause counter-effects in recognizing avatar facial expressions.     

Topological aspects of the partial realization problem

In this paper we study the topology of manifolds of rectangular Hankel matrices, motivated by the problem of partial realization. Following Fischer and Frobenius, we introduce a rank-preserving Gl(2, )-action on the space Hank(M × N) of all realM × N Hankel matrices. We derive an explicit formula for the firstn x n principal minor of transformed Hankel matrices. Extending the earlier work of Brockett, the formula is applied to introduce a manifold structure on the space Hank(n, M × N) of allM × N Hankels of rankn. We construct a cell decomposition of Hank(M × N) which induces a cellular subdivision on each of the manifolds Hank(n, M × N) wheren min (M, N). This new cell decomposition is applied to investigate the topology of partial realizations.     

Employing ai methods to control the behavior of animated interface agents

Life - like characters are increasingly gaining the attention of researchers and commercial developers of user interfaces . A strong argument in favor of using such characters in the interface is the rich repertoire of options they offer , enabling the emulation of communication styles common in human - human dialog . This contribution presents a framework for the development of presentation agents , which can be used for a broad range of applications including personalized information delivery fromthe WWW .