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Search Results: 1 - 10 of 167651 matches for " E. Brinks "
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12CO (1-0) AND (2-1) OBSERVATIONS OF ISOLATED EARLY-TYPE GALAXIES
M. Chavez,W. Wall,A. Apponi,E. Brinks
Revista mexicana de astronomía y astrofísica , 2009,
Abstract: We present 12CO(J=1-0 and 2-1) observations of a small sample of isolated early-type galaxies (ETGs). The data has been collected with the Arizona Radio Observatories (ARO) 12 m telescope at Kitt Peak. One object (KIG137) was unambiguously detected in both bands. For this detected galaxy we estimate of the molecular hydrogen mass. These observations are part of a larger project aimed at complementing existing data bases for the study of environmental e ects on the interstellar medium in ETGs.
Warm Neutral Gas at Redshift 3.4
F. H. Briggs,E. Brinks,A. M. Wolfe
Physics , 1997, DOI: 10.1086/118268
Abstract: Radio spectroscopy at 323 MHz using the Arecibo Telescope and the VLA has produced a tentative detection of the 21cm line of neutral hydrogen at Z_abs=3.38716+-0.00007 in absorption against the radio continuum of the QSO MG0201+113 (Z_em = 3.61). This redshift roughly agrees with one determined by the Westerbork Synthesis Radio Telescope and reported earlier; however the observations at different telescopes produce different results for width and optical depth of the line. If the detection holds, it provides evidence for a high column density of neutral gas that is confined to a dynamically cold layer with velocity dispersion ~10 km/s. Although the interpretation is uncertain due to a lack of detailed knowledge of the extended radio structure of the background quasar and the relative quantities of neutral gas in the cold and turbulent components, the observations specify high spin temperatures, T_s > 1000 K for both this 21cm line absorbing cloud and the turbulent component, which together have N_HI ~ 10^21.4 cm^-2. Results of optical spectroscopy require the additional presence of metal-enriched clouds of still broader velocity dispersion than the 21cm line, creating a picture which is consistent with this system being a young disk galaxy that is sufficiently evolved by z=3.4 to have collapsed to a flattened system and produced a population of stars that have aged to pollute a turbulent halo. The observations constrain the neutral gas mass of a possible 21cm line emitter associated with the intervening absorber to be less than ~(Delta V/200 km/s) 10^13 Msolar for velocity widths Delta V (FWHM) in the range 200 to 1200 km/s (H_o=100 km/s/Mpc, Omega_o=1).
Inflow and outflows in the interacting system NGC 2992/3
P. -A. Duc,E. Brinks,V. Springel,B. Pichardo
Physics , 1999,
Abstract: Whereas it is well known that gas may be driven into the core of merging disks, fueling a central AGN or a nuclear starburst, recent studies have shown that a significant fraction of the stellar/gaseous components is expelled into the intergalactic medium along tidal tails. The tidal debris might be dispersed in the intergalactic/intracluster medium where it adds to the diffuse background light such as that observed in the Coma cluster, might fall back towards the merger, or regroup to form a new generation of galaxies, the so-called tidal dwarf galaxies (TDGs). We illustrate in this paper these various phenomena with a detailed multi-wavelength study of the interacting system NGC 2992/3 (Arp 245).
NGC 765 - A disturbed H I giant
A. M. Portas,E. Brinks,M. E. Filho,A. Usero,E. M. Dyke,P. -E. Belles
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.16994.x
Abstract: We present Hi spectral line and radio-continuum VLA data of the galaxy NGC 765, complemented by optical and Chandra X-ray maps. NGC 765 has the largest Hi-to-optical ratio known to date of any spiral galaxy and one of the largest known Hi discs in absolute size with a diameter of 240 kpc measured at a surface density of 2e19 atoms/cm^2. We derive a total Hi mass of M_HI = 4.7e10 Msun, a dynamical mass of Mdyn - 5.1e11 Msun and an Hi mass to luminosity ratio of M_HI/L_B = 1.6, making it the nearest and largest "crouching giant". Optical images reveal evidence of a central bar with tightly wound low-surface brightness spiral arms extending from it. Radio-continuum (L_1.4 GHz = 1.3e21 W/Hz) and X-ray (L_X ~ 1.7e40 erg/s) emission is found to coincide with the optical core of the galaxy, compatible with nuclear activity powered by a low-luminosity AGN. We may be dealing with a galaxy that has retained in its current morphology traces of its formation history. In fact, it may still be undergoing some accretion, as evidenced by the presence of Hi clumps the size < 10 kpc and mass (10e8-10e9 Msun) of small (dIrr) galaxies in the outskirts of its Hi disc and by the presence of two similarly sized companions.
On the convergence of derivatives of B-splines to derivatives of the Gaussian function
Brinks, Ralph;
Computational & Applied Mathematics , 2008,
Abstract: in 1992 unser and colleagues proved that the sequence of normalized and scaled b-splines bm tends to the gaussian function as the order m increases, [1]. in this article the result of unser et al. is extended to the derivatives of the b-splines. as a consequence, a certain sequence of wavelets defined by b-splines, tends to the famous mexican hat wavelet. another consequence can be observed in the continuous wavelet transform (cwt) of a function analyzed with different b-spline wavelets.
On the convergence of derivatives of B-splines to derivatives of the Gaussian function
Ralph Brinks
Computational and Applied Mathematics , 2008,
Abstract: In 1992 Unser and colleagues proved that the sequence of normalized and scaled B-splines Bm tends to the Gaussian function as the order m increases, [1]. In this article the result of Unser et al. is extended to the derivatives of the B-splines. As a consequence, a certain sequence of wavelets defined by B-splines, tends to the famous Mexican hat wavelet. Another consequence can be observed in the continuous wavelet transform (CWT) of a function analyzed with different B-spline wavelets.
Simulation of Populations in a Time-, Age- and Duration Dependent Illness-Death Model
Ralph Brinks
Quantitative Biology , 2012,
Abstract: Relevant events in a three state illness-death model (IDM) of a chronic disease are the diagnosis of the disease and death with or without the disease. In this article a simulation framework for populations moving in the IDM is presented. The simulation is closely related to the concept of Lexis diagrams in event history analysis. Details of the implementation and an example of a hypothetical disease are described.
A new method for deriving incidence rates from prevalence data and its application to dementia in Germany
Ralph Brinks
Quantitative Biology , 2011,
Abstract: This paper descibes a new method for deriving incidence rates of a chronic disease from prevalence data. It is based on a new ordinary differential equation, which relates the change in the age-specific prevalence to the agespecific incidence and mortality rates. The method allows the extraction of longtudinal information from cross-sectional studies. Applicability of the method is tested in the prevalence of dementia in Germany. The derived age-specific incidence is in good agreement with published values.
On characteristics of an ordinary differential equation and a related inverse problem in epidemiology
Ralph Brinks
Quantitative Biology , 2012,
Abstract: In this work we examine the properties of a recently described ordinary differential equation that relates the age-specific prevalence of a chronic disease with the incidence and mortalities of the diseased and healthy persons. The equation has been used to estimate the incidence from prevalence data, which is an inverse problem. The ill-posedness of this problem is proven, too.
Surveillance of the Incidence of Noncommunicable Diseases (NCDs) with Prevalence Data: Theory and Application to Diabetes in Denmark
Ralph Brinks
Quantitative Biology , 2013,
Abstract: Secular trends of the incidence of NCDs are especially important as they indicate changes of the risk profile of a population. The article describes a method for detecting secular trends in the incidence from a series of prevalence data - without requiring costly follow-up studies or running a register. After describing the theory, the method is applied to the incidence of diabetes in Denmark.
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