The NASA Astrophysics Data System: Free Access to the Astronomical Literature On-line and through Email

The Astrophysics Data System (ADS) provides access to the astronomical literature through the World Wide Web. It is a NASA funded project and access to all the ADS services is free to everybody world-wide. The ADS Abstract Service allows the searching of four databases with abstracts in Astronomy, Instrumentation, Physics/Geophysics, and the LANL Preprints with a total of over 2.2 million references. The system also provides access to reference and citation information, links to on-line data, electronic journal articles, and other on-line information. The ADS Article Service contains the full articles for most of the astronomical literature back to volume 1. It contains the scanned pages of all the major journals (Astrophysical Journal, Astronomical Journal, Astronomy & Astrophysics, Monthly Notices of the Royal Astronomical Society, and Solar Physics), as well as most smaller journals back to volume 1.The ADS can be accessed through any web browser without signup or login. Alternatively an email interface is available that allows our users to execute queries via email and to retrieve scanned articles via email. This might be interesting for users on slow or unreliable links, since the email system will retry sending information automatically until the transfer is complete. There are now 9 mirror sites of the ADS available in different parts of the world to improve access. The ADS is available at: http://ads.harvard.edu This revised version was published online in July 2006 with corrections to the Cover Date.     

Reducing model complexity for explanation and prediction

Numerical models can be useful for explaining poorly understood phenomena or for reliable quantitative predictions. When modeling a multi-scale system, a ‘top-down’ approach—basing models on emergent variables and interactions, rather than explicitly on the much faster and smaller scale processes that give rise to them—facilitates both goals. Parameterizations representing emergent interactions range from highly simplified and abstracted to more quantitatively accurate. Empirically based large-scale parameterizations lead more reliably to accurate large-scale behavior than do parameterizations of much smaller scale processes. Conversely, purposefully simplified representations of model interactions can enhance a model's utility for explanation, clarifying the key feedbacks leading to an enigmatic behavior. For such potential insights to be relevant, the interactions in the model need to correspond to those in the ‘real’ system in some straightforward way. Such a correspondence usually holds for models constructed for predictive purposes, although this is not a requirement. The goals motivating a modeling endeavor help determine the most appropriate modeling strategies, as well as the most appropriate criteria for judging model usefulness.     

Dilemmas of development in Oceania: the political economy of the Tongan agro-export sector

This article critically engages with the recent diffusion of the orthodox development model in Oceania and highlights some evolving dilemmas. In particular, it explores the social, economic and ecological tensions arising from economic reforms that are exacerbating the fragility of already vulnerable nation-states and communities. In order to illustrate its arguments, a case study of the impacts of agro-export growth in Tonga is presented. Attention is drawn to the socially inequitable and ecologically unsustainable outcomes of rapid growth in this sector. In analyzing the political economy of the squash pumpkin sector, the authors point to the important role that culture plays in mediating and conditioning development outcomes. Reflecting on the Tongan case, it is argued that to better understand the implications of orthodox developmental reform in the region, research must seek to more explicitly incorporate distributional and ethical analysis.