Compression through decomposition into browse and residual images

Economical archival and retrieval of image data is becoming increasingly important considering the unprecedented data volumes expected from the Earth Observing System (EOS) instruments. For cost effective browsing the image data (possibly from remote site), and retrieving the original image data from the data archive, we suggest an integrated image browse and data archive system employing incremental transmission. We produce our browse image data with the JPEG/DCT lossy compression approach. Image residual data is then obtained by taking the pixel by pixel differences between the original data and the browse image data. We then code the residual data with a form of variable length coding called diagonal coding. In our experiments, the JPEG/DCT is used at different quality factors (Q) to generate the browse and residual data. The algorithm has been tested on band 4 of two Thematic mapper (TM) data sets. The best overall compression ratios (of about 1.7) were obtained when a quality factor of Q=50 was used to produce browse data at a compression ratio of 10 to 11. At this quality factor the browse image data has virtually no visible distortions for the images tested

Fishing and Fear Effects Interact to Shape Herbivory on Coral Reefs

Predation influences animal behavior and shapes ecological structure and function through lethal effects and fear effects. On coral reefs, fear effects can alter the distribution and intensity of herbivory by herbivorous reef fishes. This includes the browsing functional group, which potentially reverses macroalgal phase shifts and promotes reef recovery. Herbivory by multiple functional groups may increase on coral reefs through the use of NTZs (no-take zones) but few studies have examined the extent to which small-scale NTZs (\u3c 0.5 km2) influence fear effects and perceived predator presence on reefs. This study aimed to determine whether fear effects on browsers on coral reefs differ between small-scale NTZs and unprotected fished reefs by documenting how browsing fishes respond to predator models stationed on four reefs: two within NTZs (Manta and Twin Peaks) and two outside of these NTZs. We found that there was significantly greater browser presence (MaxN) and total and mass standardized bites in NTZ sites compared to fished sites, and that predator model assays experienced significantly less feeding, with no significant difference between the effect of two predator models that were used. Additionally, macroalgal removal, and total and mass standardized bites differed between the two NTZs, being higher in Manta than in Twin Peaks. Ultimately, we found that small-scale NTZs can potentially result in greater browser biomass and the ecosystem function of macroalgal removal. Further research should explore the usefulness of small-scale NTZs in sustaining other ecosystem functions apart from macroalgal removal on coral reefs

Introduction to Focus Issue: Collections in a Digital Age

In Spring 2015, a working group engaged in questions at the intersection of digital and public history at the annual National Council on Public History (NCPH) meeting held in Nashville, Tennessee. The vibrant discussion focused on the exciting and important ways by which public historians make digital, public history. Because a significant amount of work has centered on digitizing and augmenting historical archives, this special issue explores digital approaches to physical collections. Inflected by the contributors’ positioning in public history, the issue highlights how digital approaches are shaped by questions of access, audience, collaboration, interpretation, and materiality. From that discussion in Nashville arose another conversation to convey some of the practical challenges, decisions, applications, and opportunities as experienced by working group discussants. It seemed then, and with the collection of articles in this issue it is even more apparent that the lessons learned by working group discussants are widely applicable to practitioners of public history and digital history, and public, digital history. The articles in this collection develop and interrogate a range of issues beginning with methodology and then turning to case studies