Performance of transducers with segmented piezoelectric stacks using materials with high electromechanical coupling coefficient

Underwater acoustic transducers often include a stack of thickness polarized piezoelectric material pieces of alternating polarity interspersed with electrodes, bonded together and electrically connected in parallel. The stack is normally much shorter than a quarter wavelength at the fundamental resonance frequency, so that the mechanical behavior of the transducer is not affected by the segmentation. When the transducer bandwidth is less than a half octave, as has conventionally been the case, stack segmentation has no significant effect on the mechanical behavior of the device. However, when a high coupling coefficient material such as PMN-PT is used to achieve a wider bandwidth, the difference between a segmented stack and a similar piezoelectric section with electrodes only at the two ends can be significant. This paper investigates the effects of stack segmentation on the performance of wideband underwater acoustic transducers, particularly tonpilz transducer elements. Included is discussion of transducer designs using single crystal piezoelectric material with high coupling coefficient compared with more traditional PZT ceramics.Comment: 26 pages including 14 figures, one table and one appendi

Avian Diversity, Abundance, and Nest Success among Managed Prairies and Agricultural Plots in Oklahoma and Texas

Over the last 50 years, grassland birds experienced rapid declines due to habitat loss and degradation as a result of agricultural practices. Our objective was to document the diversity, abundance, and nest success of bird communities using managed prairie and agricultural plots at the Tishomingo National Wildlife Refuge (NWR) in southern Oklahoma and Hagerman NWR in northern Texas. From April 1 to July 15, 2013–2014, point count surveys, nest searches, nest monitoring, and vegetation sampling were conducted among three habitat treatments: managed prairie, unharvested wheat, and fallow agricultural plots. Species richness values for potential nesting species were higher in managed prairies at both refuges, whereas species abundance rates varied among treatments. Nest success rates were low at both refuges due to nest abandonment and predators. Due to vegetation diversity, species were more likely to nest in managed prairies compared to agricultural plots with more homogenous vegetation at both refuges. Managed prairies at both refuges were relatively small and fragmented resulting in edge effects, such as increased nest predation and brood parasitism. We recommend increasing the area of managed prairies to provide more habitat for bird species at both refuges

Figure 1 -Typical User Configurations Customer-owned ATM switch Router OC3c ATM UNI Existing Base of computers and legacy LANs SUN Workstations SUN Workstations OC3c ATM UNIs SUN Workstations ATM-Based Trial Network OC3c ATM UNI Existing Base of computers

Abstract [4] [5] [6] [7] [8] were all in the trade press with various announcements and articles during this period

IDENTIFICATION OF NONLINEAR BEHAVIOR IN A COMPOSITE STRUCTURE WITH CORE-CRUSHING DAMAGE

ABSTRACT Many damage detection methods that are applied to composite structures rely on nonlinear features in the dynami

Rubisco and carbon-concentrating mechanism co-evolution across chlorophyte and streptophyte green algae.

Green algae expressing a carbon-concentrating mechanism (CCM) are usually associated with a Rubisco-containing micro-compartment, the pyrenoid. A link between the small subunit (SSU) of Rubisco and pyrenoid formation in Chlamydomonas reinhardtii has previously suggested that specific RbcS residues could explain pyrenoid occurrence in green algae. A phylogeny of RbcS was used to compare the protein sequence and CCM distribution across the green algae and positive selection in RbcS was estimated. For six streptophyte algae, Rubisco catalytic properties, affinity for CO2 uptake (K0.5 ), carbon isotope discrimination (δ13 C) and pyrenoid morphology were compared. The length of the βA-βB loop in RbcS provided a phylogenetic marker discriminating chlorophyte from streptophyte green algae. Rubisco kinetic properties in streptophyte algae have responded to the extent of inducible CCM activity, as indicated by changes in inorganic carbon uptake affinity, δ13 C and pyrenoid ultrastructure between high and low CO2 conditions for growth. We conclude that the Rubisco catalytic properties found in streptophyte algae have coevolved and reflect the strength of any CCM or degree of pyrenoid leakiness, and limitations to inorganic carbon in the aquatic habitat, whereas Rubisco in extant land plants reflects more recent selective pressures associated with improved diffusive supply of the terrestrial environment.NE/L002507/1, BB/M007693/1, BB/I024518/1 (NERC, BBSRC and NSF). A Cambridge Trust Vice Chancellor’s award and Lucy Cavendish College, Cambridge, for supporting the PhD scholarship of MMMG. DJO and ECS acknowledge support from (BBSRC; grant number BB/I024488/1)

Interleukin-1 beta single-nucleotide polymorphism\u27s C allele is associated with elevated risk of gastric cancer in helicobacter pylori-infected Peruvians

Particular alleles of the interleukin-1B (IL-1B) gene have been correlated with increased risk of atrophic gastritis and gastric cancer in the populations of East Asia and Europe. No such data exist from Peru, a developing country with a population genotypically different from others studied and with a high prevalence of Helicobacter pylori infection and gastric cancer. We conducted a case-control study comparing 334 hospitalized patients with atrophic gastritis or gastric cancer with 158 nonatrophic gastritis patients (controls). Conditional logistic regression analysis revealed that an increased risk of atrophic gastritis (odds ratio, 5.60) and gastric cancer (odds ratio, 2.36) was associated with the IL-1B-511 C allele. Our study is the first to establish this allele as a risk for these conditions. Given the high prevalence of H. pylori and recurrence rate after treatment, IL-1B-511 single-nucleotide polymorphism analysis may identify those individuals who would benefit most from robust H. pylori eradication efforts in Peru

Noise and dynamical pattern selection

In pattern forming systems such as Rayleigh-Benard convection or directional solidification, a large number of linearly stable, patterned steady states exist when the basic, simple steady state is unstable. Which of these steady states will be realized in a given experiment appears to depend on unobservable details of the system's initial conditions. We show, however, that weak, Gaussian white noise drives such a system toward a preferred wave number which depends only on the system parameters and is independent of initial conditions. We give a prescription for calculating this wave number, analytically near the onset of instability and numerically otherwise.Comment: 12 pages, REVTEX, no figures. Submitted to Phys. Rev. Let

Advance diaspora diplomacy in a networked world

The role of diaspora in cultural exchange, international affairs and in economic development is now well established. What is new is the increasing proliferation of national strategies to harness them actively for public diplomacy. This article addresses the rise of Australia’s only formal, global diaspora network: Advance – Australia’s Global Community which has acted self-consciously to become an instrument of public diplomacy. Emerging from a small base in New York, Advance sought to ‘open doors’ for Australians in the world’s biggest market. Cultivating a strong membership base of well-connected individuals in the arts, commerce and professions, Advance developed its network centrality by building partnerships with state governments, Australian universities and federal government agencies. As an elite organisation of high-profile Australians overseas, Advance has developed into a global organisation communicating Australian culture and economic achievements to both Australian national audiences and foreign constituencies

Gauge theories on the kappa-Minkowski spacetime

This study of gauge field theories on kappa-deformed Minkowski spacetime extends previous work on field theories on this example of a noncommutative spacetime. We construct deformed gauge theories for arbitrary compact Lie groups using the concept of enveloping algebra-valued gauge transformations and the Seiberg-Witten formalism. Derivative-valued gauge fields lead to field strength tensors as the sum of curvature- and torsion-like terms. We construct the Lagrangians explicitly to first order in the deformation parameter. This is the first example of a gauge theory that possesses a deformed Lorentz covariance.Comment: 17 pages, few minor revision

Retreatment of Patients Nonresponsive to Pegylated Interferon and Ribavirin with Daily High-Dose Consensus Interferon

Background. Current treatment of chronic hepatitis C with pegylated interferon and ribavirin has the ability to eliminate viral infection in about half of the patients treated. Therapeutic options, for those with remaining chronic hepatitis, will remain limited until novel antivirals become available in the future. Consensus interferon is currently available and has demonstrated clinical efficacy with superior invitro antiviral activity, but the maximum tolerated dose is not defined. Methods. We assessed the efficacy of daily high-dose (24 ug) consensus interferon with weight-based (1000–1200 mg daily) ribavirin in HCV genotype 1-infected non-responder patients. Results. Six adverse events were documented in five patients, and the trial was terminated with no subject achieving viral clearance. Conclusions. The occurrence of serious adverse events effectively defined the upper limit of acceptable dose, while also revealing that this dose did not offer enhanced sustained viral clearance