Epistemic Conditions and Social Preferences in Trust Games

It is well-known that subjects in bilateral bargaining experiments often exhibit choice behavior suggesting there are strong reciprocators in the population. But it is controversial whether explaining this data requires a social preference model that invokes genuine strong reciprocity or whether some social preference model built on other-regarding preferences as a surrogate can explain it. Since the data precedes theory here, all the social preference models agree on most of it — making direct tests more difficult. We report results from a laboratory experiment using a novel method for testing between the classes of social preference models in the trust game that manipulates the distribution of payoff information in the game. We find evidence supporting the strong reciprocity hypothesis.social preferences, trust game, reciprocity, strong reciprocators

Observation of opto-mechanical multistability in a high Q torsion balance oscillator

We observe the opto-mechanical multistability of a macroscopic torsion balance oscillator. The torsion oscillator forms the moving mirror of a hemi-spherical laser light cavity. When a laser beam is coupled into this cavity, the radiation pressure force of the intra-cavity beam adds to the torsion wire's restoring force, forming an opto-mechanical potential. In the absence of optical damping, up to 23 stable trapping regions were observed due to local light potential minima over a range of 4 micrometer oscillator displacement. Each of these trapping positions exhibits optical spring properties. Hysteresis behavior between neighboring trapping positions is also observed. We discuss the prospect of observing opto-mechanical stochastic resonance, aiming at enhancing the signal-to-noise ratio (SNR) in gravity experiments.Comment: 4 pages, 5 figure

Fine-scale movement decisions of tropical forest birds in a fragmented landscape

The persistence of forest-dependent species in fragmented landscapes is fundamentally linked to the movement of individuals among subpopulations. The paths taken by dispersing individuals can be considered a series of steps built from individual route choices. Despite the importance of these fine-scale movement decisions, it has proved difficult to collect such data that reveal how forest birds move in novel landscapes. We collected unprecedented route information about the movement of translocated forest birds from two species in the highly fragmented tropical dry forest of Costa Rica. In this pasture-dominated landscape, forest remains in patches or riparian corridors, with lesser amounts of living fencerows and individual trees or "stepping stones." We used step selection functions to quantify how route choice was influenced by these habitat elements. We found that the amount of risk these birds were willing to take by crossing open habitat was context dependent. The forest-specialist Barred Antshrike (Thamnophilus doliatus) exhibited stronger selection for forested routes when moving in novel landscapes distant from its territory relative to locations closer to its territory. It also selected forested routes when its step originated in forest habitat. It preferred steps ending in stepping stones when the available routes had little forest cover, but avoided them when routes had greater forest cover. The forest-generalist Rufous-naped Wren (Campylorhynchus rufinucha) preferred steps that contained more pasture, but only when starting from non-forest habitats. Our results showed that forested corridors (i.e., riparian corridors) best facilitated the movement of a sensitive forest specialist through this fragmented landscape. They also suggested that stepping stones can be important in highly fragmented forests with little remaining forest cover. We expect that naturally dispersing birds and species with greater forest dependence would exhibit even stronger selection for forested routes than did the birds in our experiments

Fluctuations of thermal conductivity and morphological stability

Compositional fluctuations of the binary alloy result in the corresponding fluctuations of the thermal conductivity of the material. During crystal growth, these fluctuations can significantly modify the local temperature fields at the liquid-solid interface. This, in turn, will affect the morphological stability of the growing interface. In this work, the temperature dependence of the thermal conductivity of the solid phase has been included into the Mullins-Sekerka formalism. A significant effect on the onset of the instability of planar interface has been predicted. It has been found, in particular, that for binary systems with the segregation coefficient above unity a flat interface is always unstable. The shape of the interface fluctuation should have a single harmonic character with a well defined wavelength

Movement of Ericaphis fimbriata (Hemiptera: Aphididae) apterae on blueberry

Blueberry scorch Virus is a new and important pathogen of blueberry in British Columbia, Canada of which the blueberry-infesting aphid Ericaphis fimbriata is a known Vector. In a study of the movement of apterous E. fimbriata, significantly more aphids fell when one ladybird beetle was added to E. fimbriata infested blueberry branches than when zero, two, or four were added. Similar numbers of aphids fell in the presence or absence of beetles at low aphid density (10-30 aphids per terminal), but more fell in the presence of beetles at high aphid density (50-70 aphids per terminal). The time taken for aphids to move a minimum distance of 60 cm off infested plants onto uninfested plants decreased with increasing aphid density which has important implications for the spread of the Virus

Initial development of a high-pressure crystal growth facility: Center director's discretionary fund

A low-cost, flexible, high-pressure (600 psi) system for crystal growth and related thermophysical properties measurements was designed, assembled, and tested. The furnace system includes a magnetically coupled translation mechanism that eliminates the need for a high-pressure mechanical feedthru. The system is currently being used for continuing crystal growth experiments and thermophysical properties measurements on several material systems including Hg(1-x)Cd(x)Te, Hg(1-x)Zn(x)Te, and Hg(1-x)Zn(x)Se

Sharing Supermodular Costs

We study cooperative games with supermodular costs. We show that supermodular costs arise in a variety of situations; in particular, we show that the problem of minimizing a linear function over a supermodular polyhedron—a problem that often arises in combinatorial optimization—has supermodular optimal costs. In addition, we examine the computational complexity of the least core and least core value of supermodular cost cooperative games. We show that the problem of computing the least core value of these games is strongly NP-hard and, in fact, is inapproximable within a factor strictly less than 17/16 unless P = NP. For a particular class of supermodular cost cooperative games that arises from a scheduling problem, we show that the Shapley value—which, in this case, is computable in polynomial time—is in the least core, while computing the least core value is NP-hard.National Science Foundation (U.S.) (DMI-0426686

Epistemic Conditions and Social Preferences in Trust Games

It is well-known that subjects in bilateral bargaining experiments often exhibit choice behavior suggesting there are strong reciprocators in the population. But it is controversial whether explaining this data requires a social preference model that invokes genuine strong reciprocity or whether some social preference model built on other-regarding preferences as a surrogate can explain it. Since the data precedes theory here, all the social preference models agree on most of it — making direct tests more difficult. We report results from a laboratory experiment using a novel method for testing between the classes of social preference models in the trust game that manipulates the distribution of payoff information in the game. We find evidence supporting the strong reciprocity hypothesis

Epistemic Conditions and Social Preferences in Trust Games

It is well-known that subjects in bilateral bargaining experiments often exhibit choice behavior suggesting there are strong reciprocators in the population. But it is controversial whether explaining this data requires a social preference model that invokes genuine strong reciprocity or whether some social preference model built on other-regarding preferences as a surrogate can explain it. Since the data precedes theory here, all the social preference models agree on most of it — making direct tests more difficult. We report results from a laboratory experiment using a novel method for testing between the classes of social preference models in the trust game that manipulates the distribution of payoff information in the game. We find evidence supporting the strong reciprocity hypothesis

Techno-economic evaluation of reducing shielding gas consumption in GMAW whilst maintaining weld quality

A new method of supplying shielding gases in an alternating manner has been developed to enhance the efficiency of conventional gas metal arc welding (GMAW). However, the available literature on this advanced joining process is very sparse and no cost evaluation has been reported to date. In simple terms, the new method involves discretely supplying two different shielding gases to the weld pool at predetermined frequencies which creates a dynamic action within the liquid pool. In order to assess the potential benefits of this new method from a technical and cost perspective, a comparison has been drawn between the standard shielding gas composition of Ar/20%CO2, which is commonly used in UK and European shipbuilding industries for carbon steels, and a range of four different frequencies alternating between Ar/20%CO2 and helium. The beneficial effects of supplying the weld shielding gases in an alternating manner were found to provide attractive benefits for the manufacturing community. For example, the present study showed that compared with conventional GMAW, a 17 per cent reduction in total welding cost was achieved in the case of the alternating gas method and savings associated with a reduction in the extent of post-weld straightening following plate distortion were also identified. Also, the mechanical properties of the alternating case highlighted some marginal improvements in strength and Charpy impact toughness which were attributed to a more refined weld microstructure