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Search Results: 1 - 10 of 200870 matches for " Pétur Helgason "
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Catherine Ringen,Pétur Helgason
International Journal of English Studies (IJES) , 2004, DOI: 10.6018/ijes.4.2.47981
Abstract: In a recent paper, van Rooy & Wissing (2001) distinguish between the "broad interpretation" and the "narrow interpretation" of the feature [voice]. According to the broad interpretation, languages with a two way [voice] contrast may implement this contrast phonetically with any two of the following: voice onset precedes plosive release (prevoicing), voice onset immediately follows plosive release, voice onset substantially lags behind plosive release. According to the narrow interpretation, [voice] is employed only in languages with prevoicing in word-intial stops. According to van Rooy & Wissing, languages with prevoicing always have only regressive voice assimilation. The purpose of this paper is twofold: First we show that Swedish employs the feature [voice] on the narrow interpretation, but does not have regressive voice assimilation. Second, we present an OT account of the Swedish data which involves both features [voice] and [spread glottis].
Sigureur árni Tórearson, Limits and Life: Meaning and Metaphors in the Religious Language of Iceland (Peter Lang: American University Studies, 2012)
Pétur Bj?rgvin Torsteinsson
Nordicum-Mediterraneum , 2013,
Abstract: Review of the following book: Sigureur árni Tórearson, Limits and Life: Meaning and Metaphors in the Religious Language of Iceland (Peter Lang: American University Studies, 2012)
Effective Atomic Number Determination of Rare Earth Oxides with Scattering Intensity Ratio
A. Tur?ucu,D. Demir,P. ?nder
Science and Technology of Nuclear Installations , 2013, DOI: 10.1155/2013/738978
Abstract: Effective atomic numbers ( ) of scientific samples (rare earth) were determined experimentally by scattering of 59.54?keV gamma photons from 5?Ci 241Am annular radioactive source. The scattered gamma photons were collected by using a high-resolution HPGe semiconductor detector placed at to the incident beam. This experiment was carried out on several elements in the atomic range for 59.54?keV incident photons. Photopeak efficiency and air and sample absorption corrections were performed on Rayleigh to Compton scattering intensity ratio; then the ratio was plotted as a function of atomic number and a fit curve was constituted. The effective atomic numbers of rare earth oxide samples were determined by this fit curve. Also, related parameters were determined by absorption technique with the same incident photon energy. Obtained values from this fit curve were compared to theoretical values and were found to closely agree with theoretical calculations. 1. Introduction Effective atomic number is an important parameter that should be determined for materials in composite, alloy, and mixture form. Reliable data on the effective atomic numbers were used in radiation biology, medical physics, radiation dosimetry, nuclear industry, and space research programs. Also, the effective atomic number is used for determining the X- and γ-ray absorption fraction of materials. There are a few techniques (particle induced X-ray emissions (PIXE), proton induced gamma ray emission (PIGE), fast neutron activation analysis (FNNA), induced coupled plasma (ICP), electrical impedance methods, XRF, chemical analysis, and atomic absorption spectroscopy) to define the effective atomic number of composite materials that was created by two or more constituents. One of these techniques is total photon interaction calculation by using transmission experiments. In addition to these techniques, intensity ratio of scattered photons, emerging from suitable sample-source and detector arrangement, was a significant experimental method to determine effective atomic number in a nondestructive way. The scattered intensity ratio method is regardless of density of the sample and depends on the mixture of composite material. The above-mentioned research techniques used in a present study are subapplication of the XRF technique. Rare earth oxides of lanthanids are widely used in scientific, industrial, commercial, and medical applications. For example, praseodymium oxide in solid solution with ceria or ceria-zirconia is used as oxidation catalysis; europium oxide is used in nuclear reactor as a
Why ABC Matters Lexicography and Literary History
Jon Helgason
Culture Unbound : Journal of Current Cultural Research , 2010,
Abstract: The purpose of this article is twofold. First, I wish to discuss the origins of The Swedish Academy Dictionary against the backdrop of the social and cultural his-tory of lexicography in 18th and 19th century Europe. Second, to consider material aspects of lexicography – the dictionary as interface – in light of German media scientist Friedrich Kittler’s “media materialism”. Ultimately, both purposes intend to describe how letters and writing have been constructed and arranged through-out the course of history. In Kittler’s view, “the intimization of literature”, that took place during second half of the 18th century, brought about a fundamental change in the way language and text were perceived. However, parallel to this development an institutionalization and disciplining of language and literature took place. The rise of modern society, the nation state, print capitalism and mod-ern science in 18th century Europe necessitated (and were furthered by) a disci-plining of language and literature. This era was for these reasons a golden age for lexicographers and scholars whose work focused on the vernacular. In this article the rise of the alphabetically ordered dictionary and the corresponding downfall of the topical dictionary that occurred around 1700 is regarded as a technological threshold. This development is interesting not only within the field of history of lexicography, but arguably also, since information and thought are connected to the basic principles of mediality, this development has bearings on the epistemo-logical revolution of the 18th century witnessed in, among other things, Enlight-enment thought and literature.
The inversion of the X-ray Transform on a Compact Symmetric Space
Sigurdur Helgason
Mathematics , 2006,
Abstract: The X-ray transform on a compact symmetric space M is here inverted by means of an explicit inversion formula. The proof uses the conjugacy of the minimal closed geodesics in M and of the maximally curved totally geodesic spheres in M, proved in Math. Ann. 165 (1966), 309--317.
Non-Euclidean Analysis
Sigurdur Helgason
Mathematics , 2004,
Abstract: This paper deals with various topics in analysis on hyperbolic spaces. It surveys some recent progress in non-Euclidean Fourier Analysis and proves some new results for the geodesic Radon transform on hyperbolic spaces.
The Abel, Fourier and Radon transforms on symmetric spaces
Sigurdur Helgason
Mathematics , 2005,
Abstract: In this paper we prove a new inversion theorem and a refinement of an old support theorem for two Radon transforms on a symmetric space. Included are some new identities for the Abel transform and some results about the Fourier transform from a joint work with Rawat, Sengupta and Sitaram.
The Bounded Spherical Functions on the Cartan motion group
Sigurdur Helgason
Mathematics , 2015,
Abstract: The Bounded Spherical Functions are determined for a Cartan Motion Group
Support Theorems for Horocycles on Hyperbolic Spaces
Sigurdur Helgason
Mathematics , 2010,
Abstract: A support theorem for the horocycle Radon transform f \to \hat{f} is a property of the form \hat{f} of compact support \rightarrow f of compact support. Here we prove a variation of this result where support (\hat{f}) is outside a fixed horocycle in hyperbolic space.
Non Linear Vortex Structures in Stratified Fluid Driven by Small-Scale Helical Force  [PDF]
Anatoly Tur, Vladimir Yanovsky
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.32009

In this work, we consider the effect of a small-scale helical driving force on fluid with a stable temperature gradient with Reynolds number \"\". At first glance, this system does not have any instability. However, we show that a large scale vortex instability appears in the fluid despite its stable stratification. In a non-linear mode this instability becomes saturated and gives a large number of stationary spiral vortex structures. Among these structures there is a stationary helical soliton and a kink of the new type. The theory is built on the rigorous asymptotical method of multi-scale development.

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