Sensitivity analysis of the solar rotation to helioseismic data from GONG, GOLF and MDI observations

Accurate determination of the rotation rate in the radiative zone of the sun from helioseismic observations requires rotational frequency splittings of exceptional quality as well as reliable inversion techniques. We present here inferences based on mode parameters calculated from 2088-days long MDI, GONG and GOLF time series that were fitted to estimate very low frequency rotational splittings (nu < 1.7 mHz). These low frequency modes provide data of exceptional quality, since the width of the mode peaks is much smaller than the rotational splitting and hence it is much easier to separate the rotational splittings from the effects caused by the finite lifetime and the stochastic excitation of the modes. We also have implemented a new inversion methodology that allows us to infer the rotation rate of the radiative interior from mode sets that span l=1 to 25. Our results are compatible with the sun rotating like a rigid solid in most of the radiative zone and slowing down in the core (R_sun < 0.2). A resolution analysis of the inversion was carried out for the solar rotation inverse problem. This analysis effectively establishes a direct relationship between the mode set included in the inversion and the sensitivity and information content of the resulting inferences. We show that such an approach allows us to determine the effect of adding low frequency and low degree p-modes, high frequency and low degree p-modes, as well as some g-modes on the derived rotation rate in the solar radiative zone, and in particular the solar core. We conclude that the level of uncertainties that is needed to infer the dynamical conditions in the core when only p-modes are included is unlikely to be reached in the near future, and hence sustained efforts are needed towards the detection and characterization of g-modes.Comment: Accepted for publication in Astrophysical journal. 15 pages, 19 figure

Restructuring the Philippine Statistical System in Response to New Challenges

For a national statistical system to continue to be useful and relevant to its clients and the general public, it has to occasionally undergo an exhaustive evaluation of its performance according to certain parameters. The Philippine statistical system had recently gone through such process. This Policy Notes provides a summary of the findings and recommendations of the evaluation.statistical system, Philippine Statistical System (PSS)

Identities, selection, and contributions in a public-goods game

The notions of one's social identity and group membership have recently become topics for economic theory and experiments, and recent research has shown the importance of identity in a wide array of economic environments. But predictions are unclear when there is some trade-off between one's identity (e.g., race, gender, handedness) and potential monetary considerations. We conduct a public-goods experiment in which we permit endogenous group-formation. In a 2x2 design, we vary whether people participate in a team-building exercise and whether some people receive an endowment twice as much as others receive. We find that when both identity and financial considerations are present, high-endowment participants are strongly attracted to each other, with one's word-task-group affiliation eclipsed by the opportunity to earn more. Nevertheless, the team-building exercise greatly increases the level of contribution whether or not one is linked to people from one's team-building exercise