Using GPS as a reference frame for SAR images applied to a post eruptive period for Okmok Volcano, Aleutian Islands, Alaska

While high spatial coverage makes InSAR a popular tool to study active volcanoes its use can possess challenges for certain environments. Volcanoes along Alaska's Aleutian chain are difficult targets for InSAR as their seasonal snow cover causes decorrelation close to the volcanic caldera, their exposed location in the North Pacific renders them prone to severe atmospheric phase artifacts, and their location on small islands prevents the selection of suitable reference points necessary for deformation analysis. Existing GPS networks define a known reference frame in which SAR is better understood. Okmok volcano is one of the most active volcanoes in the Aleutian Island Chain and shows significant non-linear deformation behavior as it progresses through its eruption cycles. A stack of L-band imagery acquired by the SAR sensor PALSAR on board the JAXA Advanced Land Observing Satellite produced a post eruption deformation time series between August 2008 and October 2010. This data along with a merged DEM comprised of AirSAR SRTM and Worldview-1 stereo pair data, and GPS data from 3 continuous and 3 post eruption campaign sites was used for this study. In this research, a comparison and combination of InSAR and GPS time-series data will be presented aimed at the following research goals: 1) What is the accuracy and precision of InSAR-derived deformation estimates in such challenging environments; 2) How accurate can the deformation of the InSAR reference point be estimated from a joint analysis of InSAR and GPS deformation signals; 3) How non-linear volcanic deformation can be constrained by the measurements of a local GPS network and support the identification of residual atmospheric signals in InSAR-derived deformation time series. Further research into the combination of GPS and InSAR applied to the nonlinear aspect of volcanic deformation can enhance geodetic modeling of the volcano and associated eruption processes

Re-examination of the Effects of Food Abundance on Jaw Plasticity in Purple Sea Urchins

Morphological plasticity is a critical mechanism that animals use to cope with variations in resource availability. During periods of food scarcity, sea urchins demonstrate an increase in jaw length relative to test diameter. This trait is thought to be reversible and adaptive by yielding an increase in feeding efficiency. We directly test the hypotheses that (1) there are reversible shifts in jaw length to test diameter ratios with food abundance in individual urchins, and (2) these shifts alter feeding efficiency. Purple sea urchins, Strongylocentrotus purpuratus, were collected and placed in either high or low food treatments for 3 months, after which treatments were switched for two additional months between February and September, 2015 in La Jolla, CA (32.8674°N, 117.2530°W). Measurements of jaw length to test diameter ratios were significantly higher in low compared to high food urchins, but this was due to test growth in the high food treatments. Ratios of low food urchins did not change following a switch to high food conditions, indicating that this trait is not reversible within the time frame of this study. Relatively longer jaws were also not correlated with increased feeding efficiency. We argue that jaw length plasticity is not adaptive and is simply a consequence of exposure to high food availability, as both jaw and test growth halt when food is scarce

Voter Registration Lists: Do They Yield a Jury Representative of the Community

The passage of the Federal Act was primarily a response to the inability of the prevailing jury selection process to achieve the goal of a representative jury. The Act requires that voter registration lists be used as the primary source of names for jury selection in federal courts. A similar provision applicable to state courts is included in the Uniform Jury Selection and Service Act, adopted by the Conference of Commissioners on Uniform State Laws in 1970.6 This article will examine the rationale and effectiveness of the use of voter registration lists as a means of achieving the goal of a representative jury, the problems in the implementation of the Federal and Uniform Acts, and a possible alternative to the use of the voter registration lists as the primary source of names for jury selection

Reserve, symptoms, sex, and outcome following a single sports-related concussion

Reserve refers to the biological/cognitive differences between individuals that protect against cognitive changes following a single sports-related concussion (SRC). A single SRC can lead to brain damage and a loss of reserve. The ImPACT is a neurocognitive test which was used as a proxy for reserve. The Post-Concussion Symptom Scale (PCSS), a symptom checklist, was used to examine symptoms. It was hypothesized that pre-SRC reserve would affect post-SRC reserve, so that those with higher pre-SRC reserves would demonstrate less change in their reserve after a single SRC compared to those with low pre-SRC reserves. It was also hypothesized that females would report more emotional, cognitive, and total symptoms than males, and that cognitive symptoms would be reported more frequently than other symptoms across participants. This study used data collected by the North Coast Concussion Program, which administers the ImPACT test and the PCSS to athletes at Humboldt State University prior to each athletic season. In the event of an SRC, the test is re-administered. It was found that participants (N = 129) with low pre-SRC reserves had better outcomes compared to those with high pre-SRC reserves, and that females reported more symptoms than males. This study is the first to examine the role of reserve in predicting outcome following a single SRC using a pretest-posttest design. The validity of the ImPACT test as a proxy for reserve as well as the test structure’s influence on administrative decisions was examined. The current study also expanded on research relating to sex’s influence on symptomatology following a single SRC