Search results for "waves"
showing 10 items of 1766 documents
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…
Searching for signatures around 1920 MeV of a N-* state of three hadron nature
2009
We provide a series of arguments which support the idea that the peak seen in the gamma p -> K+ Lambda reaction around 1920 MeV should correspond to the recently predicted state of J(P) = 1/2(+) as a bound state of K(K) over bar N with a mixture of alpha(0)(980)N and f(0)(980)N components. At the same time we propose polarization experiments in that reaction as a further test of the prediction, as well as a study of the total cross-section for gamma p -> K(+)K(-)p at energies close to threshold and of d sigma/dM(inv) for invariant masses close to the two-kaon threshold.
Contribution of observed multi frequency spectrum of Alfvén waves to coronal heating
2019
Context. Whilst there are observational indications that transverse magnetohydrodynamic (MHD) waves carry enough energy to maintain the thermal structure of the solar corona, it is not clear whether such energy can be efficiently and effectively converted into heating. Phase-mixing of Alfvén waves is considered a candidate mechanism, as it can develop transverse gradient where magnetic energy can be converted into thermal energy. However, phase-mixing is a process that crucially depends on the amplitude and period of the transverse oscillations, and only recently have we obtained a complete measurement of the power spectrum for transverse oscillations in the corona. Aims. We aim to investig…
Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network
2019
Gravitational wave astronomy has been firmly established with the detection of gravitational waves from the merger of ten stellar mass binary black holes and a neutron star binary. This paper reports on the all-sky search for gravitational waves from intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network. The search uses three independent algorithms: two based on matched filtering of the data with waveform templates of gravitational wave signals from compact binaries, and a third, model-independent algorithm that employs no signal model for the incoming signal. No intermediate mass black hole binary event was detected in this sear…
All-sky search in early O3 LIGO data for continuous gravitational-wave signals from unknown neutron stars in binary systems
2021
Rapidly spinning neutron stars are promising sources of continuous gravitational waves. Detecting such a signal would allow probing of the physical properties of matter under extreme conditions. A significant fraction of the known pulsar population belongs to binary systems. Searching for unknown neutron stars in binary systems requires specialized algorithms to address unknown orbital frequency modulations. We present a search for continuous gravitational waves emitted by neutron stars in binary systems in early data from the third observing run of the Advanced LIGO and Advanced Virgo detectors using the semicoherent, GPU-accelerated, binaryskyhough pipeline. The search analyzes the most s…
Stability and extraction of bioactive sulfur compounds from Allium genus processed by traditional and innovative technologies
2017
Abstract Since ancient times, species from the Allium genus have been used in both culinary and medicinal applications. The health promoting properties, with well documented “evidence-based” studies, were attributed to the genus’ high content of bioactive organosulfur compounds. For these reasons, the organosulfur compounds have attracted interest in both food and pharmaceutical industries to be used as additives or supplements. Therefore, improvement in the extraction and stability during processing and storage of these molecules is crucial. The presented review documents the effects of traditional and innovative processing techniques on the extraction and stability of organosulfur compoun…
Phaenocompsopogon pustulatus n.gen.n. sp., a calcareous alga from the lacustrine rotliegend of the Saar-Nahe Basin (SW-Germany)
1992
Phaenocompsopogon pustulatus n. gen. n. sp. is a calcareous freshwater alga, probably of rhodophycean affinity. The fossils are mainly known from one locality in the Lower Permian of the Saar-Nahe Basin. The algal remains form a packstone in the Reckweilerhof-Bank of the Altenglan Formation. The simple thallus branches irregularly y-shaped and is covered with abundant pustules. An axial canal is characteristic, as are distinct cell features of an inner and outer cortex surrounding a structureless medulla. Most fossils are silicified and often three-dimensionally preserved. The algae lived in a wave-dominated environment, probably in offshore shallow water. The limited occurrence suggests sp…
Dynamics of boson stars and fermion-boson stars: a numerical-relativity panorama
2022
Los albores de la astronomía de ondas gravitacionales, actualmente liderada por la Colaboración LIGO-Virgo-KAGRA, abren un nuevo canal para inspeccionar la verdadera naturaleza de los objetos compactos oscuros. Los miembros más convincentes de esta categoría son los agujeros negros, de los que se cree ampliamente que están bien descritos por la métrica de Kerr cerca del equilibrio. Se han propuesto varias posibilidades teóricas más exóticas, denominadas imitadores de agujeros negros, ya que sus propiedades y dinámica se parecen en ciertos aspectos a las de los agujeros negros. Entre esos objetos compactos oscuros alternativos, las estrellas bosónicas, descritas por un campo escalar o vector…
Refractive index of GaTe under high pressure
2000
In this paper we describe two experiments, in the near- and mid-infrared, designed to investigate the evolution under pressure of the GaTe refractive index for polarization parallel and perpendicular to the crystallographic c-axis (in the layer plane). The refractive index dispersion for both light polarizations has been determined up to 5.5 GPa. It is found that the refractive index increases faster in the direction perpendicular to the c-axis than along the c-axis. To find out the origin of such a difference we used a Phillips-Van Vechten model and arrived at the conclusion that it is due to the different pressure behaviour of the Penn gap for each polarization.