Cavitation and ventilation modalities during ditching

The flow taking place in the rear part of the fuselage during the emergency landing on water is investigated experimentally in realistic conditions. To this aim, tests on a double curvature specimen have been performed at horizontal velocities ranging from 21 m/s to 45 m/s. Tests data highlight different cavitation and/or ventilation modalities which are highly dependent on the horizontal velocity, with substantial variations in the flow features occurring with velocity variations of few meters per second. For the specimen considered here, the inception of the cavitation is found at about 30 m/s, confirming that scaled model tests performed at small horizontal velocities are unable to capture the hydrodynamics correctly. By comparing pressure data, underwater movies and force measurements, it is shown that the transition from cavitation to ventilation condition has a significant effect of the longitudinal distribution of the loading which, together with inertia, aerodynamic loads and engine thrust, governs the aircraft dynamics.Comment: 11 pages, 9 figure

A novel approach for the isolation of the sound and pseudo-sound contributions from near-field pressure fluctuation measurements: analysis of the hydroacoustic and hydrodynamic perturbation in a propeller-rudder system

The main scope of the present work is to investigate the mechanisms underlying the hydroacoustic and hydrodynamic perturbations in a rudder operating in the wake of a free running marine propeller. The study consisted of detailed near-field pressure fluctuation measurements which were acquired on the face and back surfaces of the rudder, at different deflection angles. To this aim, a novel wavelet-filtering procedure was applied to separate and analyze distinctly the acoustic and hydrodynamic components of the recorded near-field pressure signals. The filtering procedure undertakes the separation of intermittent pressure peaks induced by the passage of eddy structures, interpreted as pseudo-sound, from homogenous background fluctuations, interpreted as sound. The use of wavelet in the filtering procedure allows to overcome the limitations of the earlier attempts based on frequency (wave number) band-pass filtering, retrieving the overall frequency content of both the acoustic and the hydrodynamic components and returning them as independent signals in the time domain. Acoustic and hydrodynamic pressure distributions were decomposed harmonically and compared to the corresponding topologies of the vorticity field, derived from earlier LDV measurements performed by Felli and Falchi (Exp Fluids 51(5):1385-1402, 2011). The study highlighted that the acoustic perturbation is mainly correlated with the unsteady load variations of the rudder and to the shear layer fluctuations of the propeller streamtube. Conversely, the dynamics of the propeller tip and hub vortices underlies the hydrodynamic perturbation

Comment on 'Tumour antigen expression in hepatocellular carcinoma in a low-endemic western area'

We comment on the recent study by Sideras et al (2015) that combines tissue microarrays (TMAs) and immunohistochemistry to investigate the expression pattern of 15 antigens belonging to different categories, including cancer-testis antigens and oncofetal proteins in hepatocellular carcinoma (HCC). Because current therapies for HCC are far from ideal (Ilan, 2014) and immunotherapy has been suggested as a potential therapeutic option, the Authors aimed at identifying a panel of biologically relevant tumour antigens with broad expression in a western European population of HCC patients and specific expression in the tumour tissue with no, or little, expression in surrounding non- tumoral tissue (Sideras et al., 2015)

Recent advances in the theoretical & experimental analysis of naval unit hydroacoustic performance

The present paper reviews the experimental and theoretical techniques currently used at CNR-INSEAN for hydroacoustic applications. The theoretical procedure used for hydroacoustic analyses is based upon the Lighthill\u27s acoustic analogy and concerns a hybrid hydrodynamic and hydroacoustic solver. Experimental hydroacoustics regards simultaneous velocity-pressure/visualization-pressure measurements and cross-correlation and conditional techniques. Furthermore, special signal processing techniques are used for the sake of removing unwanted noise contributions and separating the sound and pseudo-sound contributions. Examples of hydroacoustic analyses undertaken by aforementioned theoretical and experimental tools are documented in the paper

The structure of gravel-bed flow with intermediate submergence: a laboratory study

The paper reports an experimental study of the flow structure over an immobile gravel bed in open channel at intermediate submergence, with particular focus on the near-bed region. The experiments consisted of velocity measurements using three-component (stereoscopic) Particle Image Velocimetry (PIV) in near-bed horizontal plane and two-component PIV in three vertical planes that covered three distinctly different hydraulic scenarios where the ratio of flow depth to roughness height (i.e., relative submergence) changes from 7.5 to 10.8. Detailed velocity measurements were supplemented with fine-scale bed elevation data obtained with a laser scanner. The data revealed longitudinal low-momentum and high-momentum "strips'' in the time-averaged velocity field, likely induced by secondary currents. This depth-scale pattern was superimposed with particle-scale patches of flow heterogeneity induced by gravel particle protrusions. A similar picture emerged when considering second-order velocity moments. The interaction between the flow field and gravel-bed protrusions is assessed using cross correlations of velocity components and bed elevations in a horizontal plane just above gravel particle crests. The cross correlations suggest that upward and downward fluid motions are mainly associated with upstream-facing and lee sides of particles, respectively. Results also show that the relative submergence affects the turbulence intensity profiles for vertical velocity over the whole flow depth, while only a weak effect, limited to the near-bed region, is noticed for streamwise velocity component. The approximation of mean velocity profiles with a logarithmic formula reveals that log-profile parameters depend on relative submergence, highlighting inapplicability of a conventional "universal'' logarithmic law for gravel-bed flows with intermediate submergence

Inverse Geometric Approach to the Simulation of the Circular Growth. The Case of Multicellular Tumor Spheroids

We demonstrate the power of the genetic algorithms to construct the cellular automata model simulating the growth of 2-dimensional close-to-circular clusters revealing the desired properties, such as the growth rate and, at the same time, the fractal behavior of their contours. The possible application of the approach in the field of tumor modeling is outlined

Spatial distribution of elderly individuals in a medium-sized city in São Paulo State, Brazil, according to key socio-demographic and morbidity characteristics

Os Sistemas de Informação Geográfica constituem importantes instrumentos dentro da Saúde Pública como técnicas de análise da distribuição de agravos à população, e, portanto, podem ser usados no estudo da localização de indivíduos portadores de doenças crônicas. Este trabalho objetivou a realização de análise espacial da distribuição da população de sessenta anos e mais no Município de Botucatu, São Paulo, Brasil, estudando o perfil sócio-demográfico e a presença de diabetes e hipertensão arterial. Foram analisados dados de 468 idosos da amostra de inquérito populacional realizado entre 2001 e 2002. Os idosos com melhor nível sócio-econômico residem nos setores censitários de estratos sociais mais altos, o que foi estatisticamente comprovado pela utilização de técnicas de análise espacial para renda e escolaridade. Não se encontrou padrão de distribuição espacial para idosos hipertensos e diabéticos que se localizaram no mapa de forma heterogênea. O presente estudo sugere a utilização das técnicas de geoprocessamento para o mapeamento digital das áreas de abrangências das Unidades de Atenção Primária à Saúde, para um melhor controle da distribuição de idosos portadores de doenças crônicas e de sua assistência pelos profissionais de saúde.Geographic Information Systems serve as important public health tools for analyzing population disease distribution and thus for identifying individuals with chronic non-communicable diseases. The current study performed a spatial analysis of the distribution of the population 60 years and older in the city of Botucatu, São Paulo State, Brazil, studying the socio-demographic profile and the presence of diabetes mellitus and arterial hypertension. Data were analyzed from 468 elderly individuals from a population survey conducted in 2001-2002. Elders with the highest socioeconomic status live in the census tracts with the highest social strata, as proven statistically by spatial analysis techniques for income and schooling. No spatial distribution pattern was found for elderly individuals with hypertension and diabetes, who were located heterogeneously on the map. The study suggests the use of geoprocessing techniques for digital mapping of areas covered by primary health care units, aimed at better monitoring of the distribution of elderly individuals with chronic diseases and their care by health professionals

Vibrational States of the Hydrogen Isotopes on Pd(111)

The ground and excited vibrational states for the three hydrogen isotopes on the Pd(111) surface have been calculated. Notable features of these states are the high degree of anharmonicity, which is most prominently seen in the weak isotopic dependence of the parallel vibrational transition, and the narrow bandwidths of these states, which imply that atomic hydrogen is localized on a particular surface site on time scales of 100 picoseconds or more. Experiments to resolve ambiguities concerning the present system are suggested.Comment: Surface Science Letters, 302, L305 (1994

The complexity of anatomical systems

BACKGROUND: The conception of anatomical entities as a hierarchy of infinitely graduated forms and the increase in the number of observed anatomical sub-entities and structural variables has generated a growing complexity, thus highlighting new properties of organised biological matter. RESULTS: (1) Complexity is so pervasive in the anatomical world that it has come to be considered as a primary characteristic of anatomical systems. (2) Anatomical entities, when viewed at microscopic as well as macroscopic level of observation, show a different degree of complexity. (3) Complexity can reside in the structure of the anatomical system (having many diverse parts with varying interactions or an intricate architecture) or in its behaviour. Often complexity in structure and behaviour go together. (4) Complex systems admit many descriptions (ways of looking at the system) each of which is only partially true. Each way of looking at a complex system requires its own description, its own mode of analysis and its own breaking down of the system in different parts; (5) Almost all the anatomical entities display hierarchical forms: their component structures at different spatial scales or their process at different time scales are related to each other. CONCLUSION: The need to find a new way of observing and measuring anatomical entities, and objectively quantifying their different structural changes, prompted us to investigate the non-Euclidean geometries and the theories of complexity, and to apply their concepts to human anatomy. This attempt has led us to reflect upon the complex significance of the shape of an observed anatomical entity. Its changes have been defined in relation to variations in its status: from a normal (i.e. natural) to a pathological or altered state introducing the concepts of kinematics and dynamics of anatomical forms, speed of their changes, and that of scale of their observation