Learning spillover and analogy-based expectations: a multi-game experiment

We consider a multi-game interactive learning environment and ask ourselves whether long run behaviors in one game are a¤ected by behaviors in the other, i.e whether there are learning spillovers. Our main �nding is that learning spillovers arise whenever the feedback provided to subjects about past play is not easily accessible game by game and thus subjects get a more immediate impression about aggregate distributions. In such a case, long run behaviors stabilize to an analogy-based expectation equilibrium (Jehiel 2005), thereby suggesting how one should broaden the notion of equilibrium to cope with learning spillovers

Aliased noise in radiometric measurements

The magnitude of aliased noise that degrades the accuracy of continuous reconstructions of discrete radiometric measurements was evaluated as a function of the spatial response and sampling intervals of the radiometer, and of the resolution of the reconstructed measurements. A Wiener spectrum, representative of a wide range of scenes, was used to characterize the radiance fluctuations

Rational design and dynamics of self-propelled colloidal bead chains: from rotators to flagella

The quest for designing new self-propelled colloids is fuelled by the demand for simple experimental models to study the collective behaviour of their more complex natural counterparts. Most synthetic self-propelled particles move by converting the input energy into translational motion. In this work we address the question if simple self-propelled spheres can assemble into more complex structures that exhibit rotational motion, possibly coupled with translational motion as in flagella. We exploit a combination of induced dipolar interactions and a bonding step to create permanent linear bead chains, composed of self-propelled Janus spheres, with a well-controlled internal structure. Next, we study how flexibility between individual swimmers in a chain can affect its swimming behaviour. Permanent rigid chains showed only active rotational or spinning motion, whereas longer semi-flexible chains showed both translational and rotational motion resembling flagella like-motion, in the presence of the fuel. Moreover, we are able to reproduce our experimental results using numerical calculations with a minimal model, which includes full hydrodynamic interactions with the fluid. Our method is general and opens a new way to design novel self-propelled colloids with complex swimming behaviours, using different complex starting building blocks in combination with the flexibility between them.Comment: 27 pages, 10 figure

Coadsorption of Cinchona Alkaloids on Supported Palladium: Nonlinear Effects in Asymmetric Hydrogenation and Resistance of Alkaloids Against Hydrogenation

The transient behavior of the adsorption of cinchona alkaloid modifiers on Pd/TiO2 has been investigated in situ during the enantioselective hydrogenation of 4-methoxy-6-methyl-2-pyrone (1). Modifier mixtures consisting of pairs of alkaloids that alone afford the opposite enantiomers in comparable excess were applied to probe the adsorption behavior and possible nonlinear phenomena. Complementary information has been gathered from an indirect UV-vis study of the adsorption and hydrogenation of cinchonidine and quinidine on Pd/TiO2. The striking nonlinear behavior of cinchonidine-quinidine and cinchonine-quinine pairs in the hydrogenation of 1, and in the competitive saturation of the quinoline rings of the alkaloids, is attributed to differences in the adsorption strength and geometry of the alkaloids. The results are in good agreement with our former mechanistic model assuming that the quinoline ring of cinchona alkaloid and 1 adsorb parallel to the Pd surface during the enantiodifferentiating ste

Microdroplet fabrication of silver–agarose nanocomposite beads for SERS optical accumulation

Microdroplets have been used as reactors for the fabrication of agarose beads with high uniformity in shape and size, and densely loaded with silver ions, which were subsequently reduced into nanoparticles using hydrazine. The resulting nanocomposite beads not only display a high plasmonic activity, but can also trap/concentrate analytes, which can be identified by means of surface-enhanced Raman scattering (SERS) spectroscopy. The size of the beads is such that it allows the detection of a single bead under a conventional optical microscope, which is very useful to reduce the amount of material required for SERS detectio

Non-Hydrolysable Analogues of Cyclic and Branched Condensed Phosphates: Chemistry and Chemical Proteomics.

Studies into the biology of condensed phosphates almost exclusively cover linear polyphosphates. However, there is evidence for the presence of cyclic polyphosphates (metaphosphates) in organisms and for enzymatic digestion of branched phosphates (ultraphosphates) with alkaline phosphatase. Further research of non-linear condensed phosphates in biology would profit from interactome data of such molecules, however, their stability in biological media is limited. Here we present syntheses of modified, non-hydrolysable analogues of cyclic and branched condensed phosphates, called meta- and ultraphosphonates, and their application in a chemical proteomics approach using yeast cell extracts. We identify putative interactors with overlapping hits for structurally related capture compounds underlining the quality of our results. The datasets serve as starting point to study the biological relevance and functions of meta- and ultraphosphates. In addition, we examine the reactivity of meta- and ultraphosphonates with implications for their "hydrolysable" analogues: Efforts to increase the ring-sizes of meta- or cyclic ultraphosphonates revealed a strong preference to form trimetaphosphate-analogue structures by cyclization and/or ring-contraction. Using carbodiimides for condensation, the so far inaccessible dianhydro product of ultraphosphonate, corresponding to P <sub>4</sub> O <sub>11</sub> <sup>2-</sup> , was selectively obtained and then ring-opened by different nucleophiles yielding modified cyclic ultraphosphonates

Correlates of genetic monogamy in socially monogamous mammals: insights from Azara's owl monkeys

Understanding the evolution of mating systems, a central topic in evolutionary biology for more than 50 years, requires examining the genetic consequences of mating and the relationships between social systems and mating systems. Among pair-living mammals, where genetic monogamy is extremely rare, the extent of extra-group paternity rates has been associated withmale participation in infant care, strength of the pair bond and length of the breeding season. This study evaluated the relationship between two of those factors and the genetic mating system of socially monogamous mammals, testing predictions that male care and strength of pair bond would be negatively correlated with rates of extra-pair paternity (EPP). Autosomal microsatellite analyses provide evidence for genetic monogamy in a pair-living primate with bi-parental care, the Azara’s owl monkey (Aotus azarae). A phylogenetically corrected generalized least square analysis was used to relate male care and strength of the pair bond to their genetic mating system (i.e. proportions of EPP) in 15 socially monogamous mammalian species. The intensity of male care was correlated with EPP rates in mammals, while strength of pair bond failed to reach statistical significance. Our analyses showthat, once social monogamy has evolved, paternal care, and potentially also close bonds, may facilitate the evolution of genetic monogamy.German Science Foundation (HU 1746/2-1); Wenner-Gren Foundation; L.S.B. Leakey Foundation;National Geographic Society; National Science Foundation (BCS-0621020, 1219368, and 1232349); the University of Pennsylvania Research Foundation; the Zoological Society of San Dieg

Microfabricated Gaps Reveal the Effect of Geometrical Control in Wound Healing

The geometry (size and shape) of gaps is a key determinant in controlling gap closure during wound healing. However, conventional methods for creating gaps result in un‐defined geometries and poorly characterized conditions (cell death factors and cell debris), which can influence the gap closure process. To overcome these limitations, a novel method to create well‐defined geometrical gaps is developed. First, smooth muscle cells (SMCs) are seeded in variously shaped micro‐containers made out of hyaluronic acid hydrogels. Cell proliferation and cell tension induce fibrous collagen production by SMCs predominantly around the edges of the micro‐containers. Upon removal of SMCs, the selectively deposited collagen results in micro‐containers with cell‐adhesive regions along the edges and walls. Fibroblasts are seeded in these micro‐containers, and upon attaching and spreading, they naturally form gaps with different geometries. The rapid proliferation of fibroblasts from the edge results in filling and closure of the gaps. It is demonstrated that gap closure rate as well as closure mechanism is strongly influenced by geometrical features, which points to an important role for cellular tension and cell proliferation in gap closure