The Müller-Lyer illusion in ant foraging.

The Müller-Lyer illusion is a classical geometric illusion in which the apparent (perceived) length of a line depends on whether the line terminates in an arrow tail or arrowhead. This effect may be caused by economic compensation for the gap between the physical stimulus and visual fields. Here, we show that the Müller-Lyer illusion can also be produced by the foraging patterns of garden ants (Lasius niger) and that the pattern obtained can be explained by a simple, asynchronously updated foraging ant model. Our results suggest that the geometric illusion may be a byproduct of the foraging process, in which local interactions underlying efficient exploitation can also give rise to global exploration, and that visual information processing in human could implement similar modulation between local efficient processing and widespread computation

Successful discontinuation of immunoglobulin G replacement at age 10 in a patient with immunoglobulin G2 deficiency

Context: Immunoglobulin G2 deficiency that persists beyond the age of 6 years is likely to be permanent. Case report: We report on a young Japanese female, diagnosed as having immunoglobulin G2 deficiency and low anti-pneumococcal immunoglobulin G2 antibody levels when 3 years old, with a subsequent medical history of frequent respiratory infections and asthma. Monthly intravenous immunoglobulin replacement therapy was started at 4 years of age. After 8 years of age, an anti-pneumococcal immunoglobulin G2 trough level could be maintained with administration intervals longer than 6 weeks, and after 9 years and 10 months of age, therapy was discontinued. The frequency of hospital admissions was reduced by the introduction of the replacement therapy (from 8.4 times/year before the introduction to 1.1 times/year during the therapy). The patient was also able to discontinue daily medications for asthma, and serum immunoglobulin G2 was maintained at a normal level even after the cessation of replacement therapy. Conclusion: Termination of immunoglobulin replacement therapy in a patient with a symptomatic immunoglobulin G2 deficiency is possible, even for a child older than 6 years

Peak length plotted against position along the x-axis for various wing angles.

<p>Peak length plotted against position along the x-axis for various wing angles.</p

A representative snapshot illustrating a distribution of ants.

<p>The wings-out configuration is shown.</p

Results of the foraging ant simulation model.

<p>(<i>a</i>). Steady-state patterns generated by 300 ants initially distributed randomly with food sources distributed along the wings-in (upper left) and wings-out (lower left) Müller-Lyer figures and peak length plotted against the position along the x-axis (right). The movement rules described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0081714#pone-0081714-g006" target="_blank">Figure 6</a> are operated asynchronously. (<i>b</i>) Steady-state patterns under the same conditions as (<i>a</i>) except with synchronous updating. (<i>c</i>). Accumulated patterns over 6000 time steps, for various Müller-Lyer figures. A gray cell represents the cell with high density exceeding 300 ants per cell, and black represents the food source.</p

Examples of black dot density in outward and large angled -outward experiments.

<p>(<i>a</i>). Wings-out configuration. (<i>b</i>). Large angled wings-out configuration. White areas were excluded from analysis due to excessive ant density.</p

(a) The illusion effect in the ant foraging model for the variant of Müller-Lyer figures (wings-out/wings-in vs. large angled wings-out/wings-in) where central shaft is removed.

<p>(b) The illusion effect in the ant foraging model for the variants of the Müller-Lyer figure, where arrow head or tail is replaced by a box.</p

Application of lateral deviation versus position along the x-axis for various wing angles to calculate the mean effect of the Müller-Lyer illusion.

<p>The curve represents the mean value over 100 samples. Each sample represents 10,000 cumulative snapshots of simulations. The vertical bars along the curve represent the standard deviation.</p