Non-binding relationship between visual features.

The answer as to how visual attributes processed in different brain loci at different speeds are bound together to give us our unitary experience of the visual world remains unknown. In this study we investigated whether bound representations arise, as commonly assumed, through physiological interactions between cells in the visual areas. In a focal attentional task in which correct responses from either bound or unbound representations were possible, participants discriminated the color or orientation of briefly presented single bars. On the assumption that representations of the two attributes are bound, the accuracy of reporting the color and orientation should co-vary. By contrast, if the attributes are not mandatorily bound, the accuracy of reporting the two attributes should be independent. The results of our psychophysical studies reported here supported the latter, non-binding, relationship between visual features, suggesting that binding does not necessarily occur even under focal attention. We propose a task-contingent binding mechanism, postulating that binding occurs at late, post-perceptual (PP), stages through the intervention of memory

Variable Ultra-broadband and Narrowband Composite Polarization Retarders

We propose and experimentally demonstrate novel types of composite sequences of half-wave and quarter-wave polarization retarders, either permitting operation at ultra-broad spectral bandwidth or narrow bandwidth. The retarders are composed of stacked standard half-wave retarders and quarter-wave retarders of equal thickness. To our knowledge, these home-built devices outperform all commercially available compound retarders, made of several birefringent materials.Comment: 5 figures, 9 page

A dynamic Green's function for the homogeneous viscoelastic and isotropic half-space

A dynamic 3D Green's function for the homogeneous, isotropic and viscoelastic (of the Zener type) half-space is derived in a closed form. The results obtained here can be used as either stand-alone solutions for simple problems or in conjunction with a boundary integral equation formulations to account for complex boundary conditions. In the later case, mesh-reducing boundary element formulations can be constructed as an alternative method for numerical implementation purposes.Comment: 13 page

Is it better at home with my family? The effects of people and place on children's eating behavior.

The people and places children eat with can influence food consumption. This study investigates the people and places Swiss school-aged children ate with over a 7-day period and analyses the effects of eating at home with family on food consumption. Children completed a 7-day food diary documenting the foods they consumed, the people with whom they ate, and the place where they ate. Analyses were conducted for all meals and included 9911 meal occasions. Most meals (80.5%) were consumed at home with family. Generalized estimating equations were used to model the effects of the home-family dyad on the child's chance of consuming a certain food while controlling for age, gender and BMI of the child, education, nationality and BMI of the parent. Compared to eating in other dyads (e.g. school-peers or restaurant-family), eating in the home-family dyad was associated with higher consumption of vegetables (+66% and +142% at weekday lunch and dinner and +180% and +67% at weekend lunch and dinner), lower consumption of sweets (-45% and -49% at weekday lunch and dinner; -43% and -49% at weekend lunch and dinner), and fewer soft drinks (-37% and -61% at weekday lunch and dinner; -66% and -78% at weekend lunch and dinner). This study shows the positive influence of eating at home with the family on food consumption in a sample of Swiss children. Interventions and policies that encourage children and parents to eat together at home could serve as effective prevention against a poor diet

Highly efficient broadband conversion of light polarization by composite retarders

Driving on an analogy with the technique of composite pulses in quantum physics, we propose highly efficient broadband polarization converters composed of sequences of ordinary retarders rotated at specific angles with respect to their fast-polarization axes.Comment: 5 pages, 3 figures; check JOSA A 201

Counterintuitive transitions between crossing energy levels

We calculate analytically the probabilities for intuitive and counterintuitive transitions in a three-state system, in which two parallel energies are crossed by a third, tilted energy. The state with the tilted energy is coupled to the other two states in a chainwise linkage pattern with constant couplings of finite duration. The probability for a counterintuitive transition is found to increase with the square of the coupling and decrease with the squares of the interaction duration, the energy splitting between the parallel energies, and the tilt (chirp) rate. Physical examples of this model can be found in coherent atomic excitation and optical shielding in cold atomic collisions