Monitoring Results for Pfiesteria piscidida and Pfiesteria-like Organisms from Virginia Waters in 1998

Results of an extensive 1998 monitoring program for the presence of Pfiesteria-like organisms (PLO) in Virginia estuaries indicate these dinoflagellates are widely distributed in both the water column, and as cysts in the sediment, however Pfiesteria piscicida was not detected at this time. The highest concentrations of PLO were in estuaries along the Virginia shore line of the Potomac River, and in western Chesapeake Bay estuaries from the Little Wicomico River to the Rappahannock River. The most common PLO included Cryptoperidiniopsis sp. and Gymnodinium galatheanum. The lowest PLO concentrations were at ocean side locations. PLO were also present throughout the water column at stations in the lower Chesapeake Bay, being most abundant in waters above the pycnocline

Monitoring Results for Pfiesteria piscidida and Pfiesteria-like Organisms from Virginia Waters in 1998

Results of an extensive 1998 monitoring program for the presence of Pfiesteria-like organisms (PLO) in Virginia estuaries indicate these dinoflagellates are widely distributed in both the water column, and as cysts in the sediment, however Pfiesteria piscicida was not detected at this time. The highest concentrations of PLO were in estuaries along the Virginia shore line of the Potomac River, and in western Chesapeake Bay estuaries from the Little Wicomico River to the Rappahannock River. The most common PLO included Cryptoperidiniopsis sp. and Gymnodinium galatheanum. The lowest PLO concentrations were at ocean side locations. PLO were also present throughout the water column at stations in the lower Chesapeake Bay, being most abundant in waters above the pycnocline

Ultrasonic transducers based on curved lead-free piezoelectric thick films for high resolution medical imaging

International audienceKNN-based lead free ferroelectric materials are receiving much attention due to their high electromechanical properties that make them promising candidates to replace the lead-based piezoceramics that will eventually be banned by environmental regulations in many countries over the world. Studies include the development of KNN thick films that are particularly well adapted for high frequency applications due to higher wave velocities and a dielectric constant in an acceptable range for single element transducers. Here, a KNN based thick film is deposited on a curved substrate by pad-printing in order to be used in a focused high frequency transducer. This substrate is a porous lead-free KNN cylinder specifically developed to exhibit the required acoustical properties of a backing (acoustical impedance, high attenuation) and is compatible with the high sintering temperature of the KNN thick film. Electromechanical properties of the piezoelectric thick film in thickness mode were deduced (kt over 35%). This structure was used to fabricate a transducer which was characterized (relative bandwidth over 90%). Finally this transducer was integrated in a high frequency imaging system and its performance allowed skin images to be produced. To conclude, the replacement of lead-based high frequency transducers by green devices is a viable option

Identification of \u3ci\u3ePlanktothrix\u3c/i\u3e (Cyanobacteria) Blooms and Effects on the Aquatic Macroinvertebrate Community in the Non-Tidal Potomac River, USA

Using transverse cross-sectional transects, a survey of 31 km of the non-tidal Potomac River was conducted from White’s Ferry, Virginia to Brunswick, Maryland, USA, between June and September in 2013 through 2015 to assess a recurring benthic cyanobacteria bloom. Abundant benthic cyanobacteria blooms were detected during the 2014 and 2015 sampling seasons and the primary taxon was identified morphologically and molecularly as Planktothrix cf. isothrix. When present, P. cf. isothrix blooms were concentrated from river center to the Maryland shoreline. This pattern was correlated with significantly greater benthic chlorophyll-a and phycocyanin concentrations. In an apparent response to the P. cf. isothrix blooms in the study site, aquatic macroinvertebrate community assemblages were significantly different between areas with extensive benthic cyanobacterial growth compared to areas without cyanobacterial growth. Within the P. cf. isothrix mats, the percentage of pollution sensitive taxa was lower and the percentage of pollution tolerant taxa was greater. These data suggest that P. cf. isothrix can act as an ecosystem disruptor through direct impacts to the aquatic macroinvertebrate abundance and community structure within this section of the freshwater, non-tidal Potomac River

Non-Planar Pad-Printed Think-Film Focused High-Frequency Ultrasonic Transducers for Imaging and Therapeutic Applications

Pad-printed thick-film transducers have been shown to be an interesting alternative to lapped bulk piezoceramics, because the film is deposited with the required thickness, size, and geometry, thus avoiding any subsequent machining to achieve geometrical focusing. Their electromechanical properties are close to those of bulk ceramics with similar composition despite having a higher porosity. In this paper, padprinted high-frequency transducers based on a low-loss piezoceramic composition are designed and fabricated. High-porosity ceramic cylinders with a spherical top surface are used as the backing substrate. The transducers are characterized in view of imaging applications and their imaging capabilities are evaluated with phantoms containing spherical inclusions and in different biological tissues. In addition, the transducers are evaluated for their capability to produce high-acoustic intensities at frequencies around 20 MHz. High-intensity measurements, obtained with a calibrated hydrophone, show that transducer performance is promising for applications that would require the same device to be used for imaging and for therapy. Nevertheless, the transducer design can be improved, and simulation studies are performed to find a better compromise between low-power and high-power performance. The size, geometry, and constitutive materials of optimized configurations are proposed and their feasibility is discussed

Dynamics of Metal Centers Monitored by Nuclear Inelastic Scattering

Nuclear inelastic scattering of synchrotron radiation has been used now since 10 years as a tool for vibrational spectroscopy. This method has turned out especially useful in case of large molecules that contain a M\"ossbauer active metal center. Recent applications to iron-sulfur proteins, to iron(II) spin crossover complexes and to tin-DNA complexes are discussed. Special emphasis is given to the combination of nuclear inelastic scattering and density functional calculations

Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition

We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio and M\"ossbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe

An Integrated Physical, Genetic and Cytogenetic Map of Brachypodium distachyon, a Model System for Grass Research

The pooid subfamily of grasses includes some of the most important crop, forage and turf species, such as wheat, barley and Lolium. Developing genomic resources, such as whole-genome physical maps, for analysing the large and complex genomes of these crops and for facilitating biological research in grasses is an important goal in plant biology. We describe a bacterial artificial chromosome (BAC)-based physical map of the wild pooid grass Brachypodium distachyon and integrate this with whole genome shotgun sequence (WGS) assemblies using BAC end sequences (BES). The resulting physical map contains 26 contigs spanning the 272 Mb genome. BES from the physical map were also used to integrate a genetic map. This provides an independent vaildation and confirmation of the published WGS assembly. Mapped BACs were used in Fluorescence In Situ Hybridisation (FISH) experiments to align the integrated physical map and sequence assemblies to chromosomes with high resolution. The physical, genetic and cytogenetic maps, integrated with whole genome shotgun sequence assemblies, enhance the accuracy and durability of this important genome sequence and will directly facilitate gene isolation

M\"ossbauer, nuclear inelastic scattering and density functional studies on the second metastable state of Na2[Fe(CN)5NO]⋅\cdot2H2O

The structure of the light-induced metastable state SII of Na2[Fe(CN)5NO]$\cdot$2H2O 14 was investigated by transmission M\"ossbauer spectroscopy (TMS) in the temperature range 15 between 85 and 135 K, nuclear inelastic scattering (NIS) at 98 K using synchrotron 16 radiation and density functional theory (DFT) calculations. The DFT and TMS results 17 strongly support the view that the NO group in SII takes a side-on molecular orientation 18 and, further, is dynamically displaced from one eclipsed, via a staggered, to a second 19 eclipsed orientation. The population conditions for generating SII are optimal for 20 measurements by TMS, yet they are modest for accumulating NIS spectra. Optimization 21 of population conditions for NIS measurements is discussed and new NIS experiments on 22 SII are proposed