Search results for "Aves"
showing 10 items of 2443 documents
Acoustic properties of plates with unevenly distributed macro perforations backed by woven meshes
2012
A hybrid model describing the acoustic properties of plates with macro-perforations that can be unevenly distributed on the plate surface and backed by woven or precision woven meshes with microscopic perforations is proposed. The plate perforations may be of circular or rectangular shapes. Since the perforated plate may not necessarily be considered as an equivalent fluid, its surface impedance is calculated by the Maa model [Noise Control Eng. J. 29, 77-84 (1987)], whereas the Johnson-Champoux-Allard model [J. Appl. Phys. 70, 1975-1979 (1991)] is used for the mesh. It is observed that the absorption of the carrying plate seems to depend on the hydraulic diameter of the perforations and no…
Noise Analysis and Comparison of Phase-and Frequency-Detecting Readout Systems: Application to SAW Delay Line Magnetic Field Sensor
2019
International audience; Transmission surface acoustic wave (SAW) sensors are widely used in various fields of application. In order to improve the limit of detection (LOD) of such sensor systems, it is essential to understand and quantify the relevant noise sources. Only then, strategies for noise reduction can be developed. In this paper, low noise readout systems for the application with SAW sensors in an open-loop and a closed-loop configuration are presented and experimentally investigated with regard to their phase noise on the example of a SAW delay line magnetic field sensor. Besides a comprehensive analysis of the phaseand frequency modulated signals, respectively, previously derive…
The Black Block : Opaque Page as a Graphic Device
2019
The black block, a rectangle of black printing ink on the page of a book, surrounded by blank margins, is a peculiar graphic device. Its literary tradition has usually been considered to start from Tristram Shandy, which includes a renowned black page in memory of “poor Yorick”. Nevertheless, Sterne’s gimmick can be seen as an allusion to an older typographical tradition of the so-called mourning pages, which were featured in books remembering the departed decades before Tristram Shandy. In this article, we analyze the ways in which the black block is used in narrative literature, with examples chosen mainly from 20th century experimental fiction. The block proves ambivalent in that it seem…
Coupled Surface Acoustic Wave Cavities
2020
Durante las últimas dos décadas, las ondas acústicas de superficie (SAW) que se propagan en estructuras periódicas han atraído una gran atención y han sido la base de un gran número de investigaciones.Las etiquetas SAW, por ejemplo, exploran la posibilidad de utilizar dispositivos activos o pasivos para codificar información y utilizarla en muchas aplicaciones, desde el control del tráfico hasta la seguridad o la identificación de piezas en las líneas transportadoras. Se utilizan diseños muy similares para aplicaciones de detección, especialmente de temperatura y masa. Además, se han realizado una gran cantidad de avances científicos en el estudio de los cristales fonónicos (PnC). Los PnC s…
VLBA polarimetric monitoring of 3C 111
2018
Context. While studies of large samples of jets of active galactic nuclei (AGN) are important in order to establish a global picture, dedicated single-source studies are an invaluable tool for probing crucial processes within jets on parsec scales. These processes involve in particular the formation and geometry of the jet magnetic field as well as the flow itself. Aims. We aim to better understand the dynamics within relativistic magneto-hydrodynamical flows in the extreme environment and close vicinity of supermassive black holes. Methods. We analyze the peculiar radio galaxy 3C 111, for which long-Term polarimetric observations are available. We make use of the high spatial resolution of…
Física por un tubo. Mide la velocidad del sonido en el aire y diviértete con los tubos sonoros
2011
En este trabajo damos las claves para disenar un conjunto de tubos sonoros de PVC que permiten realizar una ejecucion musical en grupo con la participacion de un gran numero de personas sin cultura musical previa. Proponemos ademas la utilizacion de los tubos para el estudio cuantitativo de los fenomenos fisicos involucrados en la generacion del sonido con instrumentos de viento. Se describe la utilizacion de los tubos sonoros, en combinacion con un ordenador y un programa de analisis de sonido, para el analisis de ondas estacionarias y la determinacion de la velocidad de propagacion del sonido en el aire mediante distintos procedimientos.Palabras clave: Acustica; Ondas estacionarias; Veloc…
Jyväsjärven hoito- ja kunnostussuunnitelma
2004
Field-Grown and In Vitro Propagated Round-Leaved Sundew (Drosera rotundifolia L.) Show Differences in Metabolic Profiles and Biological Activities
2021
Drosera rotundifolia L. is a carnivorous plant used in traditional medicine for its therapeutic properties. Because of its small size, its collection in nature is laborious and different cultivation methods have been studied to ensure availability. However, only a few studies exist where the lab-grown sundew tissue and field-grown sundew would have been compared in their functionality or metabolic profiles. In this study, the antioxidant and antiviral activities of lab-grown and field-grown sundew extracts and their metabolic profiles are examined. The effect of drying methods on the chromatographic profile of the extracts is also shown. Antioxidant activity was significantly higher (5–6 ti…
Chemical composition, antimicrobial and antioxidant activity of the essential oils from Pimpinellatragium Vill. subsp. glauca (C. Presl.) C. BrulloBr…
2013
The essential oils from flowers, leaves and stems hydrodistilled from Pimpinella tragium Vill, subsp. glauca were characterised by GC and gas chromatography-mass spectrometry analysis. The C-12 nor-sesquiterpenes are the principal class of metabolites (56.6-70.6%) among which geijerene (28.9÷49.3%) and pregeijerene (10÷19.1%) predominate. Antimicrobial and antioxidant activities were evaluated. The minimum inhibitory concentration values indicate that oil obtained from the stems is the most active for antimicrobial activities and the sample with the biggest antioxidant capacity is the flower oil.
Chemical Profile and Biological Activity of Cherimoya (Annona cherimola Mill.) and Atemoya (Annona atemoya) Leaves
2020
Annona cherimola (Cherimoya) and Annona atemoya (Atemoya) are tropical plants known for their edible fruit. Scientific data suggest that their leaves, used in traditional medicine in the form of teas or infusions without evidence of toxicity, contain several bioactive compounds. However, only Annona muricata among all the Annona species is currently used in the nutraceutical field, and its dried leaves are marketed for tea preparation. In this work, we explored the nutraceutical potential of Atemoya and Cherimoya leaves, by evaluating their chemical profile and functional properties. Phytochemical analyses showed large amounts of phenolic compounds, in particular proanthocyanidins, and iden…