Faster simulation plots

Most simulation plots are heavily oversampled. Ignoring unnecessary data points dramatically reduces plot time with imperceptible effect on quality. The technique is suited to most plot devices. The departments laser printer's speed was tripled for large simulation plots by data thinning. This reduced printer delays without the expense of a faster laser printer. Surpisingly, it saved computer time as well. All plot data are now thinned, including PostScript and terminal plots. The problem, solution, and conclusions are described. The thinning algorithm is described and performance studies are presented. To obtain FORTRAN 77 or C source listings, mail a SASE to the author

Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef‐building coral Siderastrea siderea

Caribbean sea surface temperatures (SSTs) have increased at a rate of 0.2°C per decade since 1971, a rate double that of the mean global change. Recent investigations of the coral Siderastrea siderea on the Belize Mesoamerican Barrier Reef System (MBRS) have demonstrated that warming over the last 30 years has had a detrimental impact on calcification. Instrumental temperature records in this region are sparse, making it necessary to reconstruct longer SST records indirectly through geochemical temperature proxies. Here we investigate the skeletal Sr/Ca and Li/Mg ratios of S. siderea from two distinct reef zones (forereef and backreef) of the MBRS. Our field calibrations of S. siderea show that Li/Mg and Sr/Ca ratios are well correlated with temperature, although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef. These differences suggest that a secondary parameter also influences these SST proxies, highlighting the importance for site‐ and species‐specific SST calibrations. Application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral, but well‐matched reconstructed temperatures in forereef coral, both between Sr/Ca‐SSTs and Li/Mg‐SSTs, and in comparison to the Hadley Centre Sea Ice and Sea Surface Temperature record. Reconstructions generated from a combined Sr/Ca and Li/Mg multiproxy calibration improve the precision of these SST reconstructions. This result confirms that there are circumstances in which both Li/Mg and Sr/Ca are reliable as stand‐alone and combined proxies of sea surface temperature. However, the results also highlight that high‐precision, site‐specific calibrations remain critical for reconstructing accurate SSTs from coral‐based elemental proxies

Online collaboration and cooperation : the recurring importance of evidence, rationale and viability

This paper investigates collaboration in teaching and learning and draws out implications for the promotion of collaboration within online environments. It is divided into four sections. First the case for collaboration, including specifically cooperative approaches, is explored. This case revolves around the impact of collaboration on the quality of learning and on learning outcomes. Collaboration is seen as constrained by context but, if structured and rewarded, it will bring important motivational and cognitive benefits. Next, the case for online collaboration is examined. This is based on longstanding arguments about the benefits of working together albeit in an environment which offers greater reach; a mix of media; and archives of interaction. The third section of the paper compares perspectives on online collaboration with a longer tradition of research into collaboration in general; it critiques the idea that online mediation offers a paradigm change in teaching and learning. The fourth section of the paper considers future directions for promoting online collaboration

Idea Fare

Multiple articles that include descriptions of evaluations and test of information methods conducted by ACE members. Includes: On Dead Trees & Smudgy Ink, Keeping Pace with Exhibits, National ACE Media Sessions on Radio and Television, Publications, Graphics Design, Visual Aids Committe

Intrareef variations in Li/Mg and Sr/Ca sea surface temperature proxies in the Caribbean reef-building coral Siderastrea siderea

Caribbean sea surface temperatures (SSTs) have increased at a rate of 0.2°C per decade since 1971, a rate double that of the mean global change. Recent investigations of the coral Siderastrea siderea on the Belize Mesoamerican Barrier Reef System (MBRS) have demonstrated that warming over the last 30 years has had a detrimental impact on calcification. Instrumental temperature records in this region are sparse, making it necessary to reconstruct longer SST records indirectly through geochemical temperature proxies. Here we investigate the skeletal Sr/Ca and Li/Mg ratios of S. siderea from two distinct reef zones (forereef and backreef) of the MBRS. Our field calibrations of S. siderea show that Li/Mg and Sr/Ca ratios are well correlated with temperature, although both ratios are 3 times more sensitive to temperature change in the forereef than in the backreef. These differences suggest that a secondary parameter also influences these SST proxies, highlighting the importance for site‐ and species‐specific SST calibrations. Application of these paleothermometers to downcore samples reveals highly uncertain reconstructed temperatures in backreef coral, but well‐matched reconstructed temperatures in forereef coral, both between Sr/Ca‐SSTs and Li/Mg‐SSTs, and in comparison to the Hadley Centre Sea Ice and Sea Surface Temperature record. Reconstructions generated from a combined Sr/Ca and Li/Mg multiproxy calibration improve the precision of these SST reconstructions. This result confirms that there are circumstances in which both Li/Mg and Sr/Ca are reliable as stand‐alone and combined proxies of sea surface temperature. However, the results also highlight that high‐precision, site‐specific calibrations remain critical for reconstructing accurate SSTs from coral‐based elemental proxies

Modeling Susceptibility versus Resistance in Allergic Airway Disease Reveals Regulation by Tec Kinase Itk

Murine models of allergic asthma have been used to understand the mechanisms of development and pathology in this disease. In addition, knockout mice have contributed significantly to our understanding of the roles of specific molecules and cytokines in these models. However, results can vary significantly depending on the mouse strain used in the model, and in particularly in understanding the effect of specific knockouts. For example, it can be equivocal as to whether specific gene knockouts affect the susceptibility of the mice to developing the disease, or lead to resistance. Here we used a house dust mite model of allergic airway inflammation to examine the response of two strains of mice (C57BL/6 and BALB/c) which differ in their responses in allergic airway inflammation. We demonstrate an algorithm that can facilitate the understanding of the behavior of these models with regards to susceptibility (to allergic airway inflammation) (Saai) or resistance (Raai) in this model. We verify that both C57BL/6 and BALB/c develop disease, but BALB/c mice have higher Saai for development. We then use this approach to show that the absence of the Tec family kinase Itk, which regulates the production of Th2 cytokines, leads to Raai in the C57BL/6 background, but decreases Saai on the BALB/c background. We suggest that the use of such approaches could clarify the behavior of various knockout mice in modeling allergic asthma