A caste differentiation mutant elucidates the evolution of socially parasitic ants.

Most ant species have two distinct female castes-queens and workers-yet the developmental and genetic mechanisms that produce these alternative phenotypes remain poorly understood. Working with a clonal ant, we discovered a variant strain that expresses queen-like traits in individuals that would normally become workers. The variants show changes in morphology, behavior, and fitness that cause them to rely on workers in wild-type (WT) colonies for survival.

An internal expectation guides egg-laying decisions.

To better understand how animals make ethologically relevant decisions, we studied egg-laying substrate choice in . We found that flies dynamically increase or decrease their egg-laying rates while exploring substrates so as to target eggs to the best, recently visited option. Visiting the best option typically yielded inhibition of egg laying on other substrates for many minutes.

Post-Operative Low Cerebrospinal Fluid Pressure Headache in Giant Tarlov Cysts.

Giant Tarlov cysts are described as fluid-filled sacs located in the spine. They are mostly found in the sacral region, but are usually asymptomatic. The symptomatic Tarlov cysts are planned for surgical treatment in the form of laminectomy and marsupilisation of cysts.

Response thresholds alone cannot explain empirical patterns of division of labor in social insects.

The effects of heterogeneity in group composition remain a major hurdle to our understanding of collective behavior across disciplines. In social insects, division of labor (DOL) is an emergent, colony-level trait thought to depend on colony composition. Theoretically, behavioral response threshold models have most commonly been employed to investigate the impact of heterogeneity on DOL.

Colony expansions underlie the evolution of army ant mass raiding.

The mass raids of army ants are an iconic collective phenomenon, in which many thousands of ants spontaneously leave their nest to hunt for food, mostly other arthropods. While the structure and ecology of these raids have been relatively well studied, how army ants evolved such complex cooperative behavior is not understood. Here, we show that army ant mass raiding has evolved from a different form of cooperative hunting called group raiding, in which a scout directs a small group of ants to a specific target through chemical communication.

Social regulation of insulin signaling and the evolution of eusociality in ants.

Queens and workers of eusocial Hymenoptera are considered homologous to the reproductive and brood care phases of an ancestral subsocial life cycle. However, the molecular mechanisms underlying the evolution of reproductive division of labor remain obscure. Using a brain transcriptomics screen, we identified a single gene, (), which is always up-regulated in ant reproductives, likely because they are better nourished than their nonreproductive nestmates.

Neural correlates of water reward in thirsty Drosophila.

Drinking water is innately rewarding to thirsty animals. In addition, the consumed value can be assigned to behavioral actions and predictive sensory cues by associative learning. Here we show that thirst converts water avoidance into water-seeking in naive Drosophila melanogaster.

Interference fringe analysis based on centroid detection.

Phase measurement of interference fringes is an integral part of several fields in optics. Using simple straight sinusoidal fringe patterns, we describe the relationship between fringe position or phase to the centroid position when these fringes are incident on a position sensitive detector. With detailed descriptions and some experimental results, we show that a phenomenal sensitivity is possible in principle with what we believe is a new approach of phase measurement, and excellent sensitivity is readily achieved.

Simple online recognition of optical data strings based on conservative optical logic.

Optical packet switching relies on the ability of a system to recognize header information on an optical signal. Unless the headers are very short with large Hamming distances, optical correlation fails and optical logic becomes attractive because it can handle long headers with Hamming distances as low as 1. Unfortunately, the only optical logic gates fast enough to keep up with current communication speeds involve semiconductor optical amplifiers and do not lend themselves to the incorporation of large numbers of elements for header recognition and would consume a lot of power as well.

Achieving stabilization in interferometric logic operations.

Interferometric systems with amplitude beam splitters can implement reversible operations that, on detection, become Boolean operators. Being passive, they consume no energy, do not limit the operating bandwidth, and have negligible latency. Unfortunately, conventional interferometric systems are notoriously sensitive to uncontrolled disturbances.