Give and you shall receive. Give more and you shall be honored. Experimental evidence for altruism as costly signaling.

In two studies, we measured the degree and manner of reciprocation of a public good in subsequent two-by-two interactions. Both studies consisted of two phases: a public good phase and a subsequent give some game (i.e. a gradual Prisoner's dilemma game). In the first study, the public good was a financial game in the lab. In the second study, the public good games were real life student projects. The observed behavior in the subsequent interactions was consistent with the reciprocity rule, but only up to the fairness norm of equality. Students who had invested more than their fair share, did not receive more financial returns than those who had invested a fair share. However, despite the lack of financial benefits, these high investors were preferred more as future team mates (Study 1), or received more social rewards (Study 2). We interpret these findings in terms of altruism as costly signaling.Altruism; Cooperation; Costly signaling; Prisoner's dilemma game; Reputations; Studies;

Logarithmic temperature profiles in the ultimate regime of thermal convection

We report on the theory of logarithmic temperature profiles in very strongly developed thermal convection in the geometry of a Rayleigh-Benard cell with aspect ratio one and discuss the degree of agreement with the recently measured profiles in the ultimate state of very large Rayleigh number flow. The parameters of the log-profile are calculated and compared with the measure ones. Their physical interpretation as well as their dependence on the radial position are discussed.Comment: 14 pages, no figur

Digit extension: validation of a new biometric variable.

This paper reports on a new biometric variable, namely digit extension. We calculated the average length of the second and fourth digit rather than their ratio and we entitled this biometric digit extension. In a first study, we showed that digit extension is related more strongly to a self-concept associated with vigor (masculine trait) than with supportiveness (feminine trait) in men, but not in women. In a second study we found that digit extension and risk seeking (masculine trait) were related in men, but not in women. In a third study we found that for both men and women a higher digit extension was related to more altruistic behavior in a situation where it is in accordance with either masculine or feminine traits. For all studies we show divergent validity with digit ratio, indicating that digit extension is independent of digit ratio. We speculate about the hormonal influences that determine digit extension.Altruism; Behavior; Digit extension; Finger lengths; Masculinity; Risk; Risk seeking; Studies; Validation;

How to portray men and women in advertisements? Explicit and implicit evaluations of ads depicting different gender roles.

The purpose of the current study was to gain more insight in the evaluation of advertisements containing different gender role portrayals (stereotypical/a-stereotypical) by examining explicit and implicit processes of ad evaluation. The results of two experiments showed an explicit preference for ads containing a-stereotypical images. Implicitly, we found a preference for 'warm' ads irrespective of the degree of gender stereotypicality of the ad. These findings suggest that complex stimuli such as ads may inhibit implicit gender stereotype activation. At an implicit level, warmth seems a better predictor of ad evaluation.Ad evaluation; Evaluation; Gender role portrayal; Image; Implicit association test; Implicit attitudes; Implicit stereotyping; Preference; Processes; Research; Roles; Studies;

An analysis of tropopause pressure and total ozone correlations

A study of the relationship between total ozone and tropopause pressure was carried out using Total Ozone Mapping Spectrometer (TOMS) data and National Meteorological Center (NMC) global analyses. The medium scales generally show correlations greater than 0.6 throughout the middle latitudes of both hemispheres with some regions exceeding 0.8. The areas of highest correlations seem to be associated with the storm track regions of both the Northern and Southern Hemispheres. A detailed spectral analysis is performed for the medium scales on five pairs of time series of area averaged tropopause pressure and total ozone. In middle latitudes, total ozone and tropopause pressure exhibit generally similar distributions in the power spectrum. In the subtropics and tropics the power in ozone drops off more rapidly with increasing frequency than the power in tropopause pressure. Only in the Northern Hemisphere middle latitudes does one find a clear association between increased power in ozone and tropopause pressure and maxima in the coherency spectrum. Results for large scales are more complicated, showing generally positive correlations at middle latitudes

Effective interaction between a colloid and a soft interface near criticality

Within mean-field theory we determine the universal scaling function for the effective force acting on a single colloid located near the interface between two coexisting liquid phases of a binary liquid mixture close to its critical consolute point. This is the first study of critical Casimir forces emerging from the confinement of a fluctuating medium by at least one soft interface, instead by rigid walls only as studied previously. For this specific system, our semi-analytical calculation illustrates that knowledge of the colloid-induced, deformed shape of the interface allows one to accurately describe the effective interaction potential between the colloid and the interface. Moreover, our analysis demonstrates that the critical Casimir force involving a deformable interface is accurately described by a universal scaling function, the shape of which differs from that one for rigid walls.Comment: 19 pages, 11 figure

Velocity profiles in strongly turbulent Taylor-Couette flow

We derive the velocity profiles in strongly turbulent Taylor-Couette flow for the general case of independently rotating cylinders. The theory is based on the Navier-Stokes equations in the appropriate (cylinder) geometry. In particular, we derive the axial and the angular velocity profiles as functions of distance from the cylinder walls and find that both follow a logarithmic profile, with downwards-bending curvature corrections, which are more pronounced for the angular velocity profile as compared to the axial velocity profile, and which strongly increase with decreasing ratio $\eta$ between inner and outer cylinder radius. In contrast, the azimuthal velocity does not follow a log-law. We then compare the angular and azimuthal velocity profiles with the recently measured profiles in the ultimate state of (very) large Taylor numbers. Though the {\em qualitative} trends are the same -- down-bending for large wall distances and (properly shifted and non-dimensionalized) angular velocity profile $\omega^+(r)$ being closer to a log-law than (properly shifted and non-dimensionalized) azimuthal velocity profile $u^+_{\varphi}(r)$ -- {\em quantitative} deviations are found for large wall distances. We attribute these differences to the Taylor rolls and the height dependence of the profiles, neither of which are considered in the theoretical approach

Revised structure of haemoventosin

The structure of the lichen pigment haemoventosin has been revised to 3,4,6,9-tetrahydro-5,10-dihydroxy-7-methoxy-3S-methyl-1,6,9-trioxo-1H-naphtho-[2,3-c]pyran (3), mainly on the basis of long-range δC/δH correlations observed in 2D HMBC NMR experiments and long-range δH/δD isotope effects observed in partial deuteriation experiments with 10-O-acetylhaemoventosin; ortho- and para-quinonoid structures were distinguished by means of the transacetylation inferred in the sodium dithionite reduction of 10-O-acetylhaemoventosin

Phase Locking of the Boreal Summer Atmospheric Response to Dry Land Surface Anomalies in the Northern Hemisphere

Past modeling simulations, supported by observational composites, indicate that during boreal summer, dry soil moisture anomalies in very different locations within the United States continental interior tend to induce the same upper-tropospheric circulation pattern: a high anomaly forms over west-central North America and a low anomaly forms to the east. The present study investigates the causes of this apparent phase locking of the upper-level circulation response and extends the investigation to other land regions in the Northern Hemisphere. The phase locking over North America is found to be induced by zonal asymmetries in the local basic state originating from North American orography. Specifically, orography-induced zonal variations of air temperature, those in the lower troposphere in particular, and surface pressure play a dominant role in placing the soil moisture-forced negative Rossby wave source (dominated by upper-level divergence anomalies) over the eastern leeside of the Western Cordillera, which subsequently produces an upper-level high anomaly over west-central North America, with the downstream anomalous circulation responses phase-locked by continuity. The zonal variations of the local climatological atmospheric circulation, manifested as a climatological high over central North America, help shape the spatial pattern of the upper-level circulation responses. Considering the rest of the Northern Hemisphere, the northern Middle East exhibits similar phase locking, also induced by local orography. The Middle Eastern phase locking, however, is not as pronounced as that over North America; North America is where soil moisture anomalies have the greatest impact on the upper-tropospheric circulation