Full field inversion in photoacoustic tomography with variable sound speed

Recently, a novel measurement setup has been introduced to photoacoustic tomography, that collects data in the form of projections of the full 3D acoustic pressure distribution at a certain time instant. Existing imaging algorithms for this kind of data assume a constant speed of sound. This assumption is not always met in practice and thus leads to erroneous reconstructions. In this paper, we present a two-step reconstruction method for full field detection photoacoustic tomography that takes variable speed of sound into account. In the first step, by applying the inverse Radon transform, the pressure distribution at the measurement time is reconstructed point-wise from the projection data. In the second step, one solves a final time wave inversion problem where the initial pressure distribution is recovered from the known pressure distribution at the measurement time. For the latter problem, we derive an iterative solution approach, compute the required adjoint operator, and show its uniqueness and stability

A Native Hymenopteran Predator of \u3ci\u3eAgonopterix Alstroemeriana\u3c/i\u3e (Lepidoptera: Oecophoridae) in East-Central Illinois

Agonopterix alstroemeriana is a European oecophorid moth that defoliates poison hemlock (Conium maculatum), a noxious Eurasian weed extensively naturalized throughout temperate Australia, New Zealand, North America, and South America. Throughout western North America, and increasingly in the Midwest and Northeast, A. alstroemeriana has been utilized in poison hemlock eradication programs. We report, for the first time, predation on A. alstroemeriana by Euodynerus foraminatus (Hymenoptera: Eumenidae), a native solitary wasp that paralyzes these and other lepidopteran larvae and uses them to provision its nests. The presence of an effective predator may reduce the impact of A. alstroemeriana in biological control programs

Structure, geometry and formation of brittle discontinuities in anisotropic crystalline rocks of the Central Gotthard Massif, Switzerland

Abstract.: Spatial occurrence, structural architecture and formation of brittle fault zones and joints are investigated by outcrop observations, scanline mapping, and light- and scanning electron microscopy in an anisotropic crystalline rock mass (e.g. granites, para-gneisses and schists) of the central Gotthard massif in the Swiss Alps. The analysis presented illustrates that several pre-fault anisotropic features (i.e. dykes, ductile shear zones, foliation and presumably a pre-existing meso-scale fracture set) control the nucleation and propagation of brittle faults. Three sets of brittle fault zones striking NE-SW, NNE-SSW and WNWESE can be distinguished. They formed through cataclasis at temperatures below 300°C, and were activated predominately in a strike-slip regime. Up to five joint sets were mapped and characterized according to orientation, frequency, spacing and formation. Finally a regional fan structure was established in the Gotthard Pass area, encompassing the main foliation, steeply dipping joints and brittle fault zones, each of which shows the same orientation and location of the symmetry plane (NE-SW orientated

Regional Flow Simulation in Fractured Aquifers Using Stress-Dependent Parameters

A model function relating effective stress to fracture permeability is developed from Hooke's law, implemented in the tensorial form of Darcy's law, and used to evaluate discharge rates and pressure distributions at regional scales. The model takes into account elastic and statistical fracture parameters, and is able to simulate real stress-dependent permeabilities from laboratory to field studies. This modeling approach gains in phenomenology in comparison to the classical ones because the permeability tensors may vary in both strength and principal directions according to effective stresses. Moreover this method allows evaluation of the fracture porosity changes, which are then translated into consolidation of the medium.Comment: 10 pages, 7 figures, submitted to Ground Water 201

PRETTY: Grazing altimetry measurements based on the interferometric method

The exploitation of signals stemming from global navigation systems for passive bistatic radar applications has beenproposed and implemented within numerous studies. The fact that such missions do not rely on high power amplifiersand that the need of high gain antennas with large geometrical dimensions can be avoided, makes them suitable forsmall satellite missions. Applications where a continuous high coverage is needed, as for example disaster warning,have the demand for a large number of satellites in orbit, which in turn requires small and relatively low cost satellites.The proposed PRETTY (Passive Reflectometry and Dosimetry) mission includes a demonstrator payload for passivereflectometry and scatterometry focusing on very low incidence angles whereby the direct and reflected signal will bereceived via the same antenna. The correlation of both signals will be done by a specific FPGA based hardwareimplementation. The demonstration of a passive reflectometer without the use of local code replica implicitly showsthat also signals of unknown data modulation can be exploited for such a purpose.The PRETTY mission is proposed by an Austrian consortium with RUAG GmbH as prime contractor, relying on theresults from a previous CubeSat mission (OPS-SAT) conducted by TU Graz under ESA contract [18]. Within thepresent paper we will describe the architecture of the passive reflectometer payload within this 3U CubeSat mission anddiscuss operational routines and constraints to be elaborated in the frame of the proposed activity

Structural basis of control of inward rectifier Kir2 channel gating by bulk anionic phospholipids

Inward rectifier potassium (Kir) channel activity is controlled by plasma membrane lipids. Phosphatidylinositol-4,5-bisphosphate (PIP(2)) binding to a primary site is required for opening of classic inward rectifier Kir2.1 and Kir2.2 channels, but interaction of bulk anionic phospholipid (PL(−)) with a distinct second site is required for high PIP(2) sensitivity. Here we show that introduction of a lipid-partitioning tryptophan at the second site (K62W) generates high PIP(2) sensitivity, even in the absence of PL(−). Furthermore, high-resolution x-ray crystal structures of Kir2.2[K62W], with or without added PIP(2) (2.8- and 2.0-Å resolution, respectively), reveal tight tethering of the C-terminal domain (CTD) to the transmembrane domain (TMD) in each condition. Our results suggest a refined model for phospholipid gating in which PL(−) binding at the second site pulls the CTD toward the membrane, inducing the formation of the high-affinity primary PIP(2) site and explaining the positive allostery between PL(−) binding and PIP(2) sensitivity

Hybodont sharks of the English Bathonian and Callovian (Middle Jurassic).

Recent bulk sampling and study of museum collections has revealed a high diversity of hybodont sharks from the English Bathonian, with 15 species being recognised. In addition, study of dental and skeletal material from the English Callovian has allowed the diagnosis of a new genus and species, Planohybodus peterboroughensis gen. et sp. nov., allowing the Bathonian species Hybodus grossiconus Agassiz to be referred to Planohybodus. Two additional new genera, Secarodus and Frangerodus, are erected for the Bathonian taxa Hybodus polyprion Agassiz and Strophodus lingualis Woodward, respectively. Egertonodus duffini sp. nov. is described and the diagnosis of Egertonodus based on dental material is discussed. The previously unrecorded Hybodus sp., Parvodus sp., and Lonchidion sp. are recognised but left in open nomenclature. Asteracanthus medius (Owen) is recorded in the British Bathonian for the first time, and the status of Bathonian nominal species of Asteracanthus are assessed. Bathonian hybodonts showed great diversity in trophic ecology and many of the species are specific to particular palaeoenvironments

Using Knowledge Management Technology to Aid Knowledge Transfer

This paper describes a practical system designed to create, maintain and manage teaching materials using knowledge management techniques. This system uses ISO Topic Maps to represent and store knowledge, which subsequently are accessed online or converted into multiple forms suitable for use as lecture materials. The benets of such a generic semantic knowledge store that represents information in a shallow and concise fashion include the ease of selecting pertinent material and of any subsequent transformation into presentations and lecture materials. Separating content lters and presentation rendering from the actual knowledge also allows for very ecient long-term maintenance of the knowledge. This environment has evolved over the last six years and become a major factor in reducing the eorts necessary to keep course materials up to date where the subjects cover fast-changing, emerging technologies and therefore require frequent revision. Our knowledge management approach to maintaining teaching materials also suggested itself as a novel assessment format: in advanced subjects we have had quite positive experiences with tasking students with research exercises where the deliverable is such a topic map instead of the more common essay format. This paper gives an overview of our integrated environment and outlines the benets and positive results we have experienced with its use for teaching purposes

Metabolic analysis of the interaction between plants and herbivores

Insect herbivores by necessity have to deal with a large arsenal of plant defence metabolites. The levels of defence compounds may be increased by insect damage. These induced plant responses may also affect the metabolism and performance of successive insect herbivores. As the chemical nature of induced responses is largely unknown, global metabolomic analyses are a valuable tool to gain more insight into the metabolites possibly involved in such interactions. This study analyzed the interaction between feral cabbage (Brassica oleracea) and small cabbage white caterpillars (Pieris rapae) and how previous attacks to the plant affect the caterpillar metabolism. Because plants may be induced by shoot and root herbivory, we compared shoot and root induction by treating the plants on either plant part with jasmonic acid. Extracts of the plants and the caterpillars were chemically analysed using Ultra Performance Liquid Chromatography/Time of Flight Mass Spectrometry (UPLCT/MS). The study revealed that the levels of three structurally related coumaroylquinic acids were elevated in plants treated on the shoot. The levels of these compounds in plants and caterpillars were highly correlated: these compounds were defined as the ‘metabolic interface’. The role of these metabolites could only be discovered using simultaneous analysis of the plant and caterpillar metabolomes. We conclude that a metabolomics approach is useful in discovering unexpected bioactive compounds involved in ecological interactions between plants and their herbivores and higher trophic levels.