We describe a new algorithm for robust principal component analysis (PCA) of electromagnetic (EM) array data, extending previously developed multivariate methods to include arrays with large data gaps, and only partial overlap between site occupations. Our approach is based on a criss-cross regression scheme in which polarization parameters and spatial...
Low-angle normal faulting is widely discussed as a possible mechanism for continental extension, however, unambiguous evidence for seismogenic low-angle normal faulting is lacking. Here, we investigate seismicity along a short segment of the Pumqu-Xianza Rift (PXR) in southern Tibet, where the HiCLIMB seismic array recorded over 500 earthquakes between 2004...
We describe novel hybrid algorithms for inversion of electromagnetic geophysical data, combining the computational and storage efficiency of a conjugate gradient approach with an Occam scheme for regularization and step-length control. The basic algorithm is based on the observation that iterative solution of the symmetric (Gauss-Newton) normal equations with conjugate...
Organisms use a variety of environmental cues to orient their movements in three-dimensional space. Here, we show that the upward movement of young Chinook salmon (Oncorhynchus tshawytscha) emerging from gravel nests is influenced by the geomagnetic field. Fish in the ambient geomagnetic field travelled farther upwards through substrate than did...
The influence of the flood pulse on fish populations has been posited, but infrequently tested or quantified. Here, we tested the effect of habitat on population size, using Prochilodus nigricans as a case study species. Floodplain habitat was based on the littoral zone area occupied by P. nigricans to feed....
Some eyespots are thought to deflect attack away from the vulnerable body, yet there is limited empirical evidence for this function and its adaptive advantage. Here, we demonstrate the conspicuous ventral hindwing eyespots found on Bicyclus anynana butterflies protect against invertebrate predators, specifically praying mantids. Wet season (WS) butterflies with...
The inaccessibility of open ocean habitat and the cryptic nature of small animals are fundamental problems when assessing the distribution of oceanic-stage sea turtles and other marine animals sharing similar life-history traits. Most methods that estimate patterns of abundance cannot be applied in situations that are extremely data limited. Here,...
We used simulated magnetic displacements to test orientation preferences of juvenile steelhead trout (Oncorhynchus mykiss) exposed to magnetic fields existing at the northernmost and southernmost boundaries of their oceanic range. Fish reared in natural magnetic conditions distinguished between these two fields by orienting in opposite directions, with headings that would...
To better understand the role of tensegrity structures in biological systems and their application to robotics, the Dynamic Tensegrity Robotics Lab at NASA Ames Research Center, Moffett Field, CA, USA, has developed and validated two software environments for the analysis, simulation and design of tensegrity robots. These tools, along with...
A wide variety of organisms show morphologically plastic responses to environmental
stressors but in general these changes are not reversible. Though less common, reversible
morphological structures are shown by a range of species in response to changes in predators,
competitors, or food. Theoretical analysis indicates that reversible plasticity increases fitness...
For decades, the bio-duck sound has been recorded in the Southern Ocean,
but the animal producing it has remained a mystery. Heard mainly during
austral winter in the Southern Ocean, this ubiquitous sound has been
recorded in Antarctic waters and contemporaneously off the Australian
west coast. Here, we present conclusive...
Few studies to date have demonstrated widespread biological impacts of ocean
acidification (OA) under conditions currently found in the natural environment.
From a combined survey of physical and chemical water properties
and biological sampling along the Washington–Oregon–California coast in
August 2011, we show that large portions of the shelf waters...
North Atlantic right whales (Eubalaena glacialis) were found in an important nineteenth century whaling area east of southern Greenland, from which they were once thought to have been extirpated. In 2007–2008, a 1-year passive acoustic survey was conducted at five sites in and near the ‘Cape Farewell Ground’, the former...
A critical seasonal event for anadromous Chinook salmon (Oncorhynchus tshawytscha) is the time at which adults migrate from the ocean to breed in freshwater. We investigated whether allelic variation at the circadian rhythm genes, OtsClock1a and OtsClock1b, underlies genetic control of migration timing among 42 populations in North America. We...
Mucous-mesh grazers (pelagic tunicates and thecosome pteropods) are common in oceanic waters and efficiently capture, consume and repackage particles many orders of magnitude smaller than themselves. They feed using an adhesive mucous mesh to capture prey particles from ambient seawater. Historically, their grazing process has been characterized as non-selective, depending...
Density-independent and density-dependent variables both affect the spatial distributions of species. However, their effects are often separately addressed using different analytical techniques. We apply a spatially explicit regression framework that incorporates localized, interactive and threshold effects of both density-independent (water temperature) and density-dependent (population abundance) variables, to study the spatial...
Fluxes of sulphur dioxide to wheat were measured over two growing seasons. The deposition velocity, vg, depended primarily on affinities of surfaces for SO2 and varied from less than 0.1 to about 1.5cms−1. Stomata were an important sink, and diurnal changes in stomatal resistance accounted for most of the variation...
The dipyridophenazine (dppz) based ruthenium polypyridyl complexes are known as molecular ‘light-switches’ for DNA. This property is poised to serve in diagnostic and therapeutic applications, but the poor cellular uptake restricts their use in live cells. Herein, we show that the cellular uptake, and more interestingly and surprisingly, the nuclear...
Highly migratory marine species can travel long distances and across entire ocean basins to reach foraging and breeding grounds, yet gaps persist in our knowledge of oceanic dispersal and habitat use. This is especially true for sea turtles, whose complex life history and lengthy pelagic stage present unique conservation challenges....
Air-breathing marine animals face a complex set of physical challenges associated with diving that affect the decisions of how to optimize feeding. Baleen whales (Mysticeti) have evolved bulk-filter feeding mechanisms to efficiently feed on dense prey patches. Baleen whales are central place foragers where oxygen at the surface represents the...