6,713 research outputs found
Quarkonium+ production in coherent hadron - hadron interactions at LHC energies
In this paper we study the ( and )
production in coherent hadron - hadron interactions at LHC energies.
Considering the ultrarelativistic protons as a source of photons, we estimate
the cross section using the
non-relativistic QCD (NRQCD) factorization formalism and considering different
sets of values for the matrix elements. Our results for the total cross sections and rapidity distributions at
and 14 TeV demonstrate that the experimental analysis of the
production at LHC is feasible.Comment: 6 pages, 3 figures, 1 table. Improved version with a new figure.
Version to be published in European Physical Journal
Fractal analysis of weld defect patterns obtained by radiographic tests
This paper presents a fractal analysis of radiographic patterns obtained from
specimens with three types of inserted welding defects: lack of fusion, lack of
penetration, and porosity. The study focused on patterns of carbon steel beads
from radiographs of the International Institute of Welding (IIW). The
radiographs were scanned using a greyscale with 256 levels, and the fractal
features of the surfaces constructed from the radiographic images were
characterized by means of Hurst, detrended-fluctuation, and minimal-cover
analyses. A Karhunen-Loeve transformation was then used to classify the curves
obtained from the fractal analyses of the various images, and a study of the
classification errors was performed. The obtained results indicate that fractal
analyses can be an effective additional tool for pattern recognition of weld
defects in radiographic tests.Comment: 7 pages, 2 figures. To appear AIP Conference Proceedings - QNDE 200
Gas Metallicity of Narrow-Line Regions in Narrow-Line Seyfert 1 Galaxies and Broad-Line Seyfert 1 Galaxies
We investigate gas metallicity of narrow-line regions in narrow-line Seyfert
1 galaxies (NLS1s) and broad-line ones (BLS1s) in order to examine whether or
not there is a difference in the gas metallicity between the two populations of
Seyfert 1 galaxies. We apply two methods to study this issue. One is to use the
emission-line flux ratio of [N II]6583/H_alpha in combination with some other
optical emission-line flux ratios. This method, which has been often applied to
Seyfert 2 galaxies, suggests that the gas metallicity of narrow-line regions is
indistinguishable or possibly higher in BLS1s than in NLS1s. On the contrary,
the other method in which only forbidden emission-line fluxes are used results
in that NLS1s tend to possess metal-richer gas in the narrow-line regions than
BLS1s. We point out that this inconsistency may be owing to the contamination
of the broad component of permitted lines into the narrow component of ones in
the first method. Since the results derived by using only forbidden
emission-line fluxes do not suffer from any uncertainty of the fitting function
for the broad component of Balmer lines, the results from this method are more
reliable than those derived by using permitted lines. We thus conclude that the
gas metallicity of narrow-line regions tends to be higher in NLS1s than in
BLS1s.Comment: 12 pages including 10 figures, to appear in The Astrophysical Journa
Estudo da inibição de HMF e furfural na fermentação do hidrolisado de madeira de Eucalyptus urophylla.
The forgotten whale : a bibliometric analysis and literature review of the North Atlantic sei whale Balaenoptera borealis
Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of John Wiley & Sons for personal use, not for redistribution. The definitive version was published in Mammal Review 42 (2012): 235-272, doi:10.1111/j.1365-2907.2011.00195.x.1. A bibliometric analysis of the literature on the sei whale Balaenoptera borealis is presented. Research output on the species is quantified and compared with research on four other whale species. The results show a significant increase in research for all species except the sei whale. Research output is characterized chronologically and by oceanic basin.
2. The species’ distribution, movements, stock structure, feeding, reproduction, abundance, acoustics, mortality and threats are reviewed for the North Atlantic, and the review is complemented with previously unpublished data.
3. Knowledge on the distribution and movements of the sei whale in the North Atlantic is still mainly derived from whaling records. Movement patterns and winter distribution are not clear. Surveys in some known summering areas show that the species has changed its distribution in parts of its previously known range.
4. With the present information, it is impossible to determine whether or not the North Atlantic sei whale population is subdivided into biological units. Abundance estimates are fragmentary and cover a restricted part of the summering habitat.
5. In the North Atlantic, sei whales seem to be stenophagous, feeding almost exclusively on calanoid copepods and euphausiids. On feeding grounds, they are associated with oceanic frontal systems, but how they find and explore these structures has not been fully investigated.
6. The available data on vital rates are based on whaling-derived studies and are 25 years old or older. Despite increasing human and environmentally induced pressures, there are no current estimates for mortality and population trends.
7. Current research needs include the clear definition of stock units, reliable abundance estimates, studies of distribution and migration that incorporate the identification of wintering areas, acquisition of up-to-date data on reproduction and mortality, and investigations into the consequences of environmental changes for the species.Mónica Silva was supported by an FCT postdoctoral grant (SFRH/BPD/29841/2006), and Rui Prieto was supported by an FCT doctoral grant (SFRH/BD/32520/2006)
Avaliação da fermentação de caldo de sorgo sacarino empregando leveduras comerciais.
Visando explorar o potencial deste material, empregando o caldo de sorgo sacarino BRS 511, foi avaliado o comportamento de três leveduras comerciais (CAT-1, PE-2 e SA-1) em quatro ciclos fermentativos
Avaliação do bagaço de biomassa de genótipos de sorgo sacarino para a produção de etanol celulósico.
Neste trabalho avaliou-se 4 genótipos de sorgo sacarino, BRS 506; 508; 509 e 511 para produção de etanol
Citizen motivation on the go: the role of psychological empowerment
Although advances in technology now enable people to communicate ‘anytime, anyplace’, it is not
clear how citizens can be motivated to actually do so. This paper evaluates the impact of three
principles of psychological empowerment, namely perceived self-efficacy, sense of community and
causal importance, on public transport passengers’ motivation to report issues and complaints
while on the move. A week-long study with 65 participants revealed that self-efficacy and
causal importance increased participation in short bursts and increased perceptions of service
quality over longer periods. Finally, we discuss the implications of these findings for citizen
participation projects and reflect on design opportunities for mobile technologies that motivate citizen
participation.info:eu-repo/semantics/publishedVersio
5D gravitational waves from complexified black rings
In this paper we construct and briefly study the 5D time-dependent solutions
of general relativity obtained via double analytic continuation of the black
hole (Myers-Perry) and of the black ring solutions with a double
(Pomeransky-Senkov) and a single rotation (Emparan-Reall). The new solutions
take the form of a generalized Einstein-Rosen cosmology representing
gravitational waves propagating in a closed universe. In this context the
rotation parameters of the rings can be interpreted as the extra wave
polarizations, while it is interesting to state that the waves obtained from
Myers-Perry Black holes exhibit an extra boost-rotational symmetry in higher
dimensions which signals their better behavior at null infinity. The analogue
to the C-energy is analyzed.Comment: 18 pages, 4 figures. References added, introduction and conclusions
are amended, some issues related to singularity structure and symmetries are
discussed. Matches the print version to appear in JHE
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