Possible Antarctic Location for ‘Missing’ Ice Sheet

	Bruce Luyendyk, left, and Douglas S. Wilson

New research by UCSB scientists indicates a possible Antarctic location for ice that seemed to be missing at a key point in climate history 34 million years ago. The research, which has important implications for climate change, is described in a paper published in Geophysical Research Letters, a journal of the American Geophysical Union. “Using data from prior geological studies, we have constructed a model for the topography of West Antarctic bedrock at the time of the start of the global climate transition from warm ‘greenhouse’ earth to the current cool ‘icehouse’ earth some 34 million years ago,” explained Douglas S. Wilson, first author and an associate research geophysicist with the Department of Earth Science and Marine Science Institute. Wilson and his co-author, Bruce Luyendyk, a professor in the Department of Earth Science, discovered that, contrary to most current models for bedrock elevations of West Antarctica, the bedrock in the past was of much higher elevation and covered a much larger area than today.

Ranking the ‘Hotspots’ of Human Impact on Coastal Areas
Coastal marine ecosystems are at risk worldwide as a result of human activities, according to scientists at UCSB’s National Center for Ecological Analysis and Synthesis (NCEAS), who have recently published a study in the Journal of Conservation Letters. The authors have performed the first integrated analysis of all coastal areas of the world. “Resource management and conservation in coastal waters must address a litany of impacts from human activities, from the land, such as urban runoff and other types of pollution, and from the sea,” said Benjamin S. Halpern, first author. “One of the great challenges is to decide where and how much to allocate limited resources to tackling these problems,” he said. “Our results identify where it is absolutely imperative that land-based threats are addressed –– so-called hotspots of land-based impact –– and where these land-based sources of impact are minimal or can be ignored.” The hottest hotspot is at the mouth of the Mississippi River, explained Halpern, with the other top 10 in Asia and the Mediterranean. “These are areas where conservation efforts will almost certainly fail if they don’t directly address what people are doing on land upstream from these locations.”

Potential Drug Delivery System

	Erkki Ruoslahti

Scientists have discovered a potential new drug delivery system. The finding is a biological mechanism for delivery of nanoparticles into tissue. The results are published in the Proceedings of the National Academy of Sciences. “This work is important because when giving a drug to a patient, it circulates in the blood stream, but often doesn’t get into the tissue,” said senior author Erkki Ruoslahti, of the Burnham Institute for Medical Research at UCSB. “This is especially true with tumors. We believe this method will lead to better, more efficient delivery of drugs.” In this study, the scientists used prostate cancer cells as their target, but the method could apply to any type of cell. The scientists developed a peptide, a small piece of protein that can carry “cargo” for delivery into the cell. The cargo could be a nanoparticle, or even a cell. Riding on the peptide, the cargo gets out of the blood vessel and penetrates the tissue.

The Importance of Niche Differences in Biodiversity

	Jonathan Levine

Scientists have found strong evidence that niche differences are critical to biodiversity. Their findings are published in the journal Nature. “Ecologists have long assumed that species differences in how they use the environment are key to explaining the large number of species we see all around us, but the importance of such niches have never been field tested,” said first author Jonathan M. Levine, associate professor in UCSB’s Department of Ecology, Evolution, and Marine Biology. Levine and his co-author, Janneke HilleRisLambers, a former postdoctoral fellow at UCSB, did field testing of small plants. These plants were found in northern Santa Barbara County on rocky outcrops, where diversity is very high. They used a combination of mathematical techniques and experimental approaches to remove niche differences from these communities. “Our work is important because it resolves a century-old biodiversity puzzle,” said Levine. “Why doesn’t the single best competitor exclude all others in the community?” Ecological theory has posed two possible answers to the coexistence conundrum. According to Levine, the classic argument is that niche differences allow species to divide up the environment. The alternative is that competitors are so evenly matched that no single species can win. The new study provides the first strong evidence that species’ differences are responsible for their coexistence.

Pushing Quantum Mechanics to Higher Levels

	John Martinis and Matthew Neeley

Scientists have devised a new type of superconducting circuit that behaves quantum mechanically –– but has up to five levels of energy instead of the usual two. The findings are published in an August issue of Science. These circuits act like artificial atoms in that they can only gain or lose energy in packets, or quanta, by jumping between discrete energy levels. “In our previous work, we focused on systems with just two energy levels, ‘qubits,’ because they are the quantum analog of ‘bits,’ which have two states — on and off,” said Matthew Neeley, first author and a graduate student at UCSB. He explained that in this research they operated a quantum circuit as a more complicated artificial atom with up to five energy levels. The generic term for such a system is “qudit,” where ‘d’ refers to the number of energy levels –– in this case, ‘d’ equals five. “This is the quantum analog of a switch that has several allowed positions, rather than just two,” said Neeley. “Because it has more energy levels, the physics of a qudit is richer than for just a single qubit. This allows us to explore certain aspects of quantum mechanics that go beyond what can be observed with a qubit.”