528 research outputs found
Ladder type operators and recurrence relations for the radial wave functions of the N-th dimensional oscillators and hydrogenlike atoms
Using the method described in [11], we present some new ladder type operators and recurrence relations for the radial wave functions of the N-th dimensional isotropic harmonic oscillators and the hydrogenlike atoms
On the Properties of Special Functions on the linear-type lattices
We present a general theory for studying the difference analogues of special
functions of hypergeometric type on the linear-type lattices, i.e., the
solutions of the second order linear difference equation of hypergeometric type
on a special kind of lattices: the linear type lattices. In particular, using
the integral representation of the solutions we obtain several
difference-recurrence relations for such functions. Finally, applications to
-classical polynomials are given
Electromagnetic radiation from collisions at almost the speed of light: an extremely relativistic charged particle falling into a Schwarzschild black hole
We investigate the electromagnetic radiation released during the high energy
collision of a charged point particle with a four-dimensional Schwarzschild
black hole. We show that the spectra is flat, and well described by a classical
calculation. We also compare the total electromagnetic and gravitational
energies emitted, and find that the former is supressed in relation to the
latter for very high energies. These results could apply to the astrophysical
world in the case charged stars and small charged black holes are out there
colliding into large black holes, and to a very high energy collision
experiment in a four-dimensional world. In this latter scenario the calculation
is to be used for the moments just after the black hole formation, when the
collision of charged debris with the newly formed black hole is certainly
expected. Since the calculation is four-dimensional, it does not directly apply
to Tev-scale gravity black holes, as these inhabit a world of six to eleven
dimensions, although our results should qualitatively hold when extrapolated
with some care to higher dimensions.Comment: 6 pages, 2 figure
Quasinormal modes of Schwarzschild black holes in four and higher dimensions
We make a thorough investigation of the asymptotic quasinormal modes of the
four and five-dimensional Schwarzschild black hole for scalar, electromagnetic
and gravitational perturbations. Our numerical results give full support to all
the analytical predictions by Motl and Neitzke, for the leading term. We also
compute the first order corrections analytically, by extending to higher
dimensions, previous work of Musiri and Siopsis, and find excellent agreement
with the numerical results. For generic spacetime dimension number D the
first-order corrections go as . This means that
there is a more rapid convergence to the asymptotic value for the five
dimensional case than for the four dimensional case, as we also show
numerically.Comment: 12 pages, 5 figures, RevTeX4. v2. Typos corrected, references adde
A lapa do Bugio
A jazida pré-histórica do Bugio constitui uma das mais importantes grutas
sepulcrais da faixa estremenha. Encontrava-se intacta à data das primeiras
escavações, realizadas em 1957 e 1958. Vicissitudes várias que motivaram a
dissolução da primeira equipa e favoreceram diversas depredações, entretanto
realizadas, impediram que, antes do recomeço dos trabalhos, em 1966, mesmo
dos materiais recuperados, se pudessem extrair todas as informações neles
potencialmente contidas. Foi possível, a partir do estudo exaustivo do espólio conservado no Museu
de Sesimbra e no recolhido nas escavações de 1966, estabelecer a seguinte
sucessão cronológica-cultural:
Primeira ocupação - corresponde talvez à ocupação mais importante,
integrável no Neolítico recente-final estremenho. Estreitas analogias com o
"horizonte dolménico" identificado na vizinha Lapa do Fumo e datado pelo
rádio-carbono de 3090 ± 160 a. C. (SERRÃO,1978). A datação realizada no
Bugio deu 2800 ± 45 a.C.
Segunda ocupação- corresponde muito provavelmente a momento inicial
(ou pleno) do Calcolítico, definido pela presença de raros produtos, como o
recipiente de osso recolhido na sep. 7 e "ídolos" de calcário, de osso e marfim.
Terceira ocupação - Calcolítico final, campaniforme - representada pelos
Grupos de Palmela e Inciso. Trata-se da ocupação menos importante,
excessivamente valorizada em trabalhos anteriores, talvez pela grande dispersão
de fragmentos cerâmicos que não ultrapassam, contudo, nove recipientes (alguns
deles representados por apenas um fragmento): taças em calote - (I), de bordo
espessado - (I), de tipo Palmela - (I), caçoilas acampanadas - (2), e vasos
campaniformes - (2), além de dois recipientes de tipologia mal definida.Le gisement préhistorique de Bugio est l 'une des plus importantes grottes
sépulcrales du littoral de l'Estrémadure. Elle a été trouvée intacte lors des
premières fouilles, réalisées en 1957 et 1958. Diverses vicissitudes, qui devaient
aboutir à la dissolution de la première équipe de fouilleurs et favoriser le pillage
du site, empêchèrent la difusion de toute information avant la reprise des travaux
en 1966, même sur le matériel récupéré.
A partir de l' étude exhaustive du mobilier conservé au Musée de Sesimbra
et de celui qui a été découvert en 1966, on a pu établir les niveaux chronologiques
suivants: Première occupation, peut-être la plus importante, s'intégrant dans le
Néolithique récent et final de l'Estrémadure, présentant d' étroites analogies avec
"l'horizon dolménique" identifié sur le site voisin de Lapa do Fumo, daté de
3090 ± 160 a.C. par radio-carbone (SERRÃO, 1978). La datation obtenue à
Bugio est de 2800 ± 45 a.C..
Seconde occupation, correspondant très probablement à la phase initiale ou
médiane du Chalcolithique, définie par de rares productions, comme le récipient
en os recueilli dans la sépulture 7 et les "idoles" en calcaire, en os et en ivoire.
Troisième occupation (Chalcolithique final, Campaniforme) représentée
par les Groupes de Palmela et incisé. Il s'agit d'une occupation moins importante,
surévaluée dans les travaux antérieurs, peut-être en raison de la grande dispersion
des fragments de céramiques qui ne correspondaient, cependant, qu'à neuf
récipients: coupes en calotte (1 ), coupes au bord épais (1), coupes de type de
Palmela (1), casseroles en forme de cloche (2), vases campaniformes (2) et deux
récipients à la typologie mal définie
Quasinormal modes of a Schwarzschild black hole surrounded by free static spherically symmetric quintessence: Electromagnetic perturbations
In this paper, we evaluated the quasinormal modes of electromagnetic
perturbation in a Schwarzschild black hole surrounded by the static spherically
symmetric quintessence by using the third-order WKB approximation when the
quintessential state parameter in the range of . Due to
the presence of quintessence, Maxwell field damps more slowly. And when at
, it is similar to the black hole solution in the ds/Ads
spacetime. The appropriate boundary conditions need to be modified.Comment: 6 pages, 3 figure
A Multi-agent System for Outliers Accommodation in Wireless Sensor Networks
This work has been partially supported by the European Commission under the contract FP7-ICT-224282 (GINSENG) and Project CENTRO-07-ST24-FEDER-002003 (iCIS-Intelligent Computing in the Internet of Services).In monitoring applications the accuracy of data is paramount. When considering wireless sensor networks the quality of readings taken from the environment may be hampered by outliers in raw data collected from transmitters attached to nodes' analogue-to-digital converter ports. To improve the data quality sent to the base-station, a real-time data analysis should be implemented at nodes' level, while taking into account their computing power and storage limitations. This paper deals with the problem of outliers detection and accommodation in raw data. The proposed approach relies on univariate statistics within an hierarchical multi-agent framework. Results from experiments on a real monitoring scenario, at a major oil refinery plant, show the relevance of the proposed approach.publishersversionpublishe
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