The conserved Eph receptors and their Ephrin ligands regulate a number of developmental processes, including axon guidance. In contrast to the large vertebrate Eph/Ephrin family, Drosophila has a single Eph receptor and a single Ephrin ligand, both of which are expressed within the developing nervous system. Here, we show that Eph and Ephrin can act as a functional receptor-ligand pair in vivo....

A symmetry-breaking Hopi bifurcation in an O(2)-symmetric system has eigenvalues of multiplicity two. When the circular symmetry is broken these eigenvalues split into two pairs. The consequences of this splitting in the nonlinear regime are analysed in detail. It is found that the perturbation selects the phase of the standing wave (sw) solutions and that two sw branches, differing in phase by...

Baldness Hair loss Trichodynia Dr. Alfredo Rebora, Department of Dermatology, University of Genoa, Viale Benedeno XV, I-16132 Genova (Italy) No symptoms have ever been reported to accompany the development of baldness. There are patients, however, who, while complaining of hair loss, claim that their hair has become painful. We describe such discomfort and we propose the term trichodynia for it...

The spatial organization within a social insect colony is a key component of colony life. It influences individual interaction rates, resource distribution, and division of labor within the nest. Yet studies of social insect behavior are most often carried out in artificial constructions, which may change worker behavior and colony organization. We observed how workers of the ant Pheidole rhea ...

BACKGROUND AND AIMS Once human skin contacts stinging hairs of Urtica spp. (stinging nettles), the irritant is released and produces pain, wheals or a stinging sensation which may last for >12 h. However, the existence of pain-inducing toxins in the stinging hairs of Urtica thunbergiana has never been systematically demonstrated. Experiments were therefore conducted to identify the persistent p...

Root hairs project from the surface of the root to aid nutrient and water uptake and to anchor the plant in the soil. Their formation involves the precise control of cell fate and localized cell growth. We are now beginning to unravel the complexities of the molecular interactions that underlie this developmental regulation. In addition, after years of speculation, nutrient transport by root ha...

Adult male Liphistius have dense hair pads on the ventral side of their tarsi. At first glance they appear like the adhesive scopulae, which are well known from mygalomorph spiders. However, a fine structural analysis of these scopulate hairs shows that they lack the brush-like structure with tiny ‘‘endfeet’’ that is typical for such adhesive hairs. Instead, the smooth hair shaft exhibits a sma...

PURPOSE To report a case of tarantula hairs found in the cornea and discuss treatment. CASE REPORT A 16-year-old male presented with a 6-week history of right ocular irritation that began after letting his pet tarantula crawl on his face. Slit-lamp examination of the right eye revealed the presence of approximately 16 dark foreign bodies that had the appearance of small hairs. The foreign bod...

Crickets and other orthopteran insects sense air currents with a pair of abdominal appendages resembling antennae, called cerci. Each cercus in the common house cricket Acheta domesticus is covered with between 500 to 750 filiform mechanosensory hairs. The distribution of the hairs on the cerci, as well as the global patterns of their movement axes, are very stereotypical across different anima...

This paper deals with a class of perturbation planar Keplerian Hamiltonian systems, by exploiting the nondegeneracy properties circular solutions and applying implicit function theorem, we show that noncollision periodic such perturbed system bifurcate from manifold for system.