Propfan Test Assessment (PTA): Flight test report

The Propfan Test Assessment (PTA) aircraft was flown to obtain glade stress and noise data for a 2.74m (9 ft.) diameter single rotation propfan. Tests were performed at Mach numbers to 0.85 and altitudes to 12,192m (40,000 ft.). The propfan was well-behaved structurally over the entire flight envelope, demonstrating that the blade design technology was completely adequate. Noise data were characterized by strong signals at blade passage frequency and up to 10 harmonics. Cabin noise was not so high as to preclude attainment of comfortable levels with suitable wall treatment. Community noise was not excessive

Damage-Induced Modeling of Asphalt Mixtures through Computational Micromechanics and Cohesive Zone Fracture

This paper presents a computational micromechanics modeling approach to predict damage-induced mechanical response of asphalt mixtures. Heterogeneous geometric characteristics and inelastic mechanical behavior were taken into account by introducing finite element modeling techniques and a viscoelastic material model. The modeling also includes interface fracture to represent crack growth and damage evolution. The interface fracture is modeled by using a micromechanical nonlinear viscoelastic cohesive-zone constitutive relation. Fundamental material properties and fracture characteristics were measured from simple laboratory tests and then incorporated into the model to predict rate-dependent viscoelastic damage behavior of the asphalt mixture. Simulation results demonstrate that each model parameter significantly influences the mechanical behavior of the overall asphalt mixture. Within a theoretical framework of micromechanics, this study is expected to be suitable for evaluating damage-induced performance of asphalt mixtures by measuring only material properties and fracture properties of each mix component and not by recursively performing expensive laboratory tests that are typically required for continuum damage mechanics modeling

Calcific aortic valve disease and hypertension

This review addresses the role of hypertension in precipitating Calcific aortic valve disease (CAVD) and the therapeutic potential of anti-hypertensive interventions to ameliorate CAVD. CAVD was originally considered to be a degenerative disease representing the "wear and tear" of the aortic valves. More recently both conceptually and experimentally, CAVD has come to be considered the result of an active disease process, Whilst, there are some common factors in the pathology and risk factors for atherosclerosis and CAVD there are also some distinct differences. Hypertension is an established risk factor for coronary artery disease and has been recognised as a risk factor for CAVD. Angiotensin converting enzyme inhibitors have been found to have beneficial effects in CAVD and as in atherosclerosis such effects may be due to the blood pressure lowering action but also to direct pleiotropic effects on the biochemical and cellular mechanisms of disease progression in the respective tissues. The very high prevalence of hypertension in the community coupled with an aging population, a risk factor associated with both hypertension and CAVD, infers that hypertension will be one of the predominant factors that increase the impact of CAVD on human health in the coming decades

p38 MAP kinase mediated proteoglycan synthesis as a target for the prevention of atherosclerosis

The major underlying pathology of most cardiovascular disease is the chronic inflammatory disease of atherosclerosis. Type 2 diabetes, also recognised as an inflammatory condition, accelerates the development of atherosclerosis. Current therapies for atherosclerosis target risk factors such as elevated blood lipids and hypertension and are of strong but limited efficacy. The "response to retention" hypothesis states that atherosclerosis is initiated by the accumulation of lipids through binding to extracellular matrix, and this is specifically the glycosaminoglycan (GAG) chains on proteoglycans. Many vasoactive agonists stimulate changes in the structure of the GAGs which increase lipid binding and the relevant signalling pathways are a potential therapeutic target. It has recently been demonstrated that the actions of transforming growth factor b; on vascular smooth muscle proteoglycan synthesis involves signalling through p38 MAP kinase and inhibition of this pathway reduces binding of lipids. Inhibition of p38 MAP kinase will elicit a wide spread antiinflammatory response which may alleviate some of the deleterious processes in cardiovascular tissues. This article explores the potential for the actions of p38 MAP kinase inhibitors directed at proteoglycan synthesis in vascular smooth muscle to contribute to the beneficial outcomes from targeting p38 MAP kinase for the prevention of cardiovascular disease

Elasticity Theory Connection Rules for Epitaxial Interfaces

Elasticity theory provides an accurate description of the long-wavelength vibrational dynamics of homogeneous crystalline solids, and with supplemental boundary conditions on the displacement field can also be applied to abrupt heterojunctions and interfaces. The conventional interface boundary conditions, or connection rules, require that the displacement field and its associated stress field be continuous through the interface. We argue, however, that these boundary conditions are generally incorrect for epitaxial interfaces, and we give the general procedure for deriving the correct conditions, which depend essentially on the detailed microscopic structure of the interface. As a simple application of our theory we analyze in detail a one-dimensional model of an inhomogeneous crystal, a chain of harmonic oscillators with an abrupt change in mass and spring stiffness parameters. Our results have implications for phonon dynamics in nanostructures such as superlattices and nanoparticles, as well as for the thermal boundary resistance at epitaxial interfaces.Comment: 7 pages, Revte

Statistical Tests for CHDM and \LambdaCDM Cosmologies

We apply several statistical estimators to high-resolution N-body simulations of two currently viable cosmological models: a mixed dark matter model, having $\Omega_\nu=0.2$ contributed by two massive neutrinos (C+2\nuDM), and a Cold Dark Matter model with Cosmological Constant (\LambdaCDM) with $\Omega_0=0.3$ and h=0.7. Our aim is to compare simulated galaxy samples with the Perseus-Pisces redshift survey (PPS). We consider the n-point correlation functions (n=2-4), the N-count probability functions P_N, including the void probability function P_0, and the underdensity probability function U_\epsilon (where \epsilon fixes the underdensity threshold in percentage of the average). We find that P_0 (for which PPS and CfA2 data agree) and P_1 distinguish efficiently between the models, while U_\epsilon is only marginally discriminatory. On the contrary, the reduced skewness and kurtosis are, respectively, S_3\simeq 2.2 and S_4\simeq 6-7 in all cases, quite independent of the scale, in agreement with hierarchical scaling predictions and estimates based on redshift surveys. Among our results, we emphasize the remarkable agreement between PPS data and C+2\nuDM in all the tests performed. In contrast, the above \LambdaCDM model has serious difficulties in reproducing observational data if galaxies and matter overdensities are related in a simple way.Comment: 12 pages, 10 figures, LaTeX (aaspp4 macro), in press on ApJ, Vol. 479, April 199

Induction of dc voltage, proportional to the persistent current, by external ac current on system of inhomogeneous superconducting loops

A dc voltage induced by an external ac current is observed in system of asymmetric mesoscopic superconducting loops. The value and sign of this dc voltage, like the one of the persistent current, depend in a periodical way on a magnetic field with period corresponded to the flux quantum within the loop. The amplitude of the oscillations does not depend on the frequency of the external ac current (in the investigated region 100 Hz - 1 MHz) and depends on its amplitude. The latter dependence is not monotonous. The observed phenomenon of rectification is interpreted as a consequence of a dynamic resistive state induced by superposition of the external current and the persistent current. It is shown that the dc voltage can be added in system of loops connected in series: the dc voltage oscillations with amplitude up to 0.00001 V were observed in single loop, up to 0.00004 V in a system of 3 loops and up to 0.0003 V in a system of 20 loops.Comment: 5 pages, 6 figure

Field studies on the deterioration of microplastic films from ultra-thin compostable bags in soil

In recent years, some countries have replaced single-use plastic bags with bags manufactured from compostable plastic film that can be used for collecting food wastes and composted together with the waste. Because industrial compost contains undeteriorated fragments of these bags, application to field soil is a potential source of small-sized residues from these bags. This study was undertaken to examine deterioration of these compostable film microplastics (CFMPs) in field soil at three different localities in Italy. Deterioration of CFMPs did not exceed 5.7% surface area reduction during the 12-month experimental period in two sites located in Northern Italy. More deterioration was observed in the Southern site, with 7.2% surface area reduction. Deterioration was significantly increased when fields were amended with industrial compost (up to 9.6%), but not with home compost. Up to 92.9% of the recovered CFMPs were associated with the soil fungus Aspergillus flavus, with 20.1%–71.2% aflatoxin-producing isolates. Application of industrial compost resulted in a significant increase in the percentage of CFMPs associated with A. flavus. This observation provides an argument for government regulation of accumulation of CFMPs and elevation of hazardous fungi levels in agricultural soils that receive industrial compost

Cap mesenchyme cell swarming during kidney development is influenced by attraction, repulsion, and adhesion to the ureteric tip

Morphogenesis of the mammalian kidney requires reciprocal interactions between two cellular domains at the periphery of the developing organ: the tips of the epithelial ureteric tree and adjacent regions of cap mesenchyme. While the presence of the cap mesenchyme is essential for ureteric branching, how it is specifically maintained at the tips is unclear. Using ex vivo timelapse imaging we show that cells of the cap mesenchyme are highly motile. Individual cap mesenchyme cells move within and between cap domains. They also attach and detach from the ureteric tip across time. Timelapse tracks collected for >800 cells showed evidence that this movement was largely stochastic, with cell autonomous migration influenced by opposing attractive, repulsive and cell adhesion cues. The resulting swarming behaviour maintains a distinct cap mesenchyme domain while facilitating dynamic remodelling in response to underlying changes in the tip

Decay of Superflow Confined in Thin Torus: A Realization of Tunneling Quantum Fields

The quantum nucleation of phase slips in neutral superfluids confined in a thin torus is investigated by means of the collective coordinate method. We have devised, with numerical justification, a certain collective coordinate to describe the quantum nucleation process of a phase slip. Considering the quantum fluctuation around the local minimum of the action, we calculate the effective mass of the phase slip. Due to the coherence of the condensate throughout the torus, the effective mass is proportional to the circumference L of the torus, and the decay rate has a strong exponential L-dependence.Comment: 4 pages, 2 figures, REVTe