2,557 research outputs found
Integrability of Stochastic Birth-Death processes via Differential Galois Theory
Stochastic birth-death processes are described as continuous-time Markov
processes in models of population dynamics. A system of infinite, coupled
ordinary differential equations (the so-called master equation) describes the
time-dependence of the probability of each system state. Using a generating
function, the master equation can be transformed into a partial differential
equation. In this contribution we analyze the integrability of two types of
stochastic birth-death processes (with polynomial birth and death rates) using
standard differential Galois theory. We discuss the integrability of the PDE
via a Laplace transform acting over the temporal variable. We show that the PDE
is not integrable except for the (trivial) case in which rates are linear
functions of the number of individuals
Two New Andean Species of \u3ci\u3eBrachistosternus\u3c/i\u3e Pocock (Scorpiones: Bothriuridae)
Two new Andean species of the genus Brachistosternus Pocock from southern Peru and northern Chile are described: B. titicaca sp. n. from the Titicaca basin (Departamento Puno, Peru), at 3850-3900 m, and B. quiscapata sp. n. from Departamento Tacna (Peru) and Provincia Arica (Chile), at 3100-3400 m. Both species belong to the subgenus Brachistosternus (Leptosternus) Maury. They are related to the Argentinean species B. (L.) intermedius Lönnberg and B.(L.) montanus Roig Alsina. Comparisons between these four species are provided, including a combination of characters: length/width ratio of metasomal segment V, number of setae of metasomal segment V and tarsus III, ventral pigment of metasomal segments, and some details of the hemispermatophore morphology (distal lamina and cylindric apophysis). The presence of the subgenus Brachistosternus (Leptosternus) in Peru is therefore confirmed
Uncovering the host galaxy of the -ray-emitting narrow-line Seyfert 1 galaxy FBQS J1644+2619
The discovery of -ray emission from radio-loud narrow-line Seyfert 1
(NLSy1) galaxies has questioned the need for large black hole masses (> 10
M) to launch relativistic jets. We present near-infrared data of the
-ray-emitting NLSy1 FBQS J1644+2619 that were collected using the
camera CIRCE (Canarias InfraRed Camera Experiment) at the 10.4-m Gran
Telescopio Canarias to investigate the structural properties of its host galaxy
and to infer the black hole mass. The 2D surface brightness profile is modelled
by the combination of a nuclear and a bulge component with a S\'ersic profile
with index = 3.7, indicative of an elliptical galaxy. The structural
parameters of the host are consistent with the correlations of effective radius
and surface brightness against absolute magnitude measured for elliptical
galaxies. From the bulge luminosity, we estimated a black hole mass of
(2.10.2) 10 M, consistent with the values
characterizing radio-loud active galactic nuclei.Comment: 5 pages, 3 figures, 1 table. Monthly Notices of the Royal
Astronomical Society Letter, Vol. 469, L11-L1
Fotometria e calibrazione infrarossi. User Manual
Manuale dove si descrivono le procedure di calibrazione e fotometria infraross
Finding Respondents from Minority Groups
The recruitment of respondents belonging to ethnic minorities poses important challenges in social and health research. This paper reflects on the enablers and barriers to recruitment that we encountered in our research work with persons belonging to ethnic minorities. Additionally, we applied the Matching Model of Recruitment, a theoretical framework concerning minority recruitment, to guide our reflection. We also explored its applicability as a research design tool. In assessing our research experience, we learned that minority recruitment in social and health research is influenced by the social context of all key players involved in the research. Also, there are enablers and barriers within that social context facilitating or delaying the recruitment process. The main enablers to recruit respondents belonging to ethnic minorities include working with community agencies and gatekeepers who share a common vision with researchers and the latterâs ability to gain the trust of potential respondents. The main barriers include demanding too much from these same community agencies and gatekeepers and ignoring factors that could delay the completion of the research. Although we found the Matching Model of Recruitment to be an effective tool in assessing the processes of recruiting respondents belonging to ethnic minorities, further empirical research is needed to explore its usefulness during the research planning phase
Software di riduzione dati della Camera Infrarossa CAINDR. User Manual
User Manual- Software per la riduzioni dei dati infrarossi della camera CAINDR, situata nel Telescopio Carlos Sanchez (TCS) all'Osservatorio del Teide (Tenerife, Spagna
A near-infrared study of the multi-phase outflow in the type-2 quasar J1509+0434
Based on new near-infrared spectroscopic data from the instrument EMIR on the 10.4 m Gran Telescopio Canarias (GTC) we report the presence of an ionized and warm molecular outflow in the luminous type-2 quasar J150904.22+043441.8 (z = 0.1118). The ionized outflow is faster than its molecular counterpart, although the outflow sizes that we derive for them are consistent within the errors (1.34±0.18 kpc and 1.46±0.20 kpc respectively). We use these radii, the broad emission-line luminosities and in the case of the ionized outflow, the density calculated from the trans-auroral [OII] and [SII] lines, to derive mass outflow rates and kinetic coupling efficiencies. Whilst the ionized and warm molecular outflows represent a small fraction of the AGN power (â€0.033% and 0.0001% of Lbol respectively), the total molecular outflow, whose mass is estimated from an assumed warm-to-cold gas mass ratio of 6Ă 10â5, has a kinetic coupling efficiency of âŒ1.7%Lbol. Despite the large uncertainty, this molecular outflow represents a significant fraction of Lbol and it could potentially have a significant impact on the host galaxy. In addition, the quasar spectrum reveals bright and patchy narrow Paα emission extending out to 4âł (8 kpc) South-East and North-West from the active nucleus.Includes Horizon 202
The host galaxy of the gamma-ray-emitting narrow-line Seyfert 1 galaxy PKS 1502+036
The detection of gamma-ray emission from narrow-line Seyfert 1 galaxies
(NLSy1) has challenged the idea that large black hole (BH) masses (10
M) are needed to launch relativistic jets. We present near-infrared
imaging data of the gamma-ray-emitting NLSy1 PKS 1502+036 obtained with the
Very Large Telescope. Its surface brightness profile, extending to 20
kpc, is well described by the combination of a nuclear component and a bulge
with a Sersic index = 3.5, which is indicative of an elliptical galaxy. A
circumnuclear structure observed near PKS 1502+036 may be the result of galaxy
interactions. A BH mass of about M has been
estimated by the bulge luminosity. The presence of an additional faint disc
component cannot be ruled out with the present data, but this would reduce the
BH mass estimate by only 30%. These results, together with analogous
findings obtained for FBQS J1644+2619, indicate that the relativistic jets in
gamma-ray-emitting NLSy1 are likely produced by massive black holes at the
center of elliptical galaxies.Comment: 5 pages, 2 figures, 1 table, and 2 supplementary figures. Monthly
Notices of the Royal Astronomical Society Letters, Volume 478, Issue 1,
L66-L7
Perceived Social Support and Risk of Cyberbullying in Adolescents: A Systematic Review
This article analyzes the main findings of studies investigating the relationship between perceived social support and cyberbullying in adolescents. We reviewed research papers published between January 2015 and January 2020, included in the Web of Science, Scopus, PUBMED, and Science Direct databases. The protocol was previously registered on the PROSPERO International Systematic Reviews database (CRD42020176938). The article follows the PRISMA guidelines for systematic reviews (Moher et al., 2015). Out of 1929 surveyed articles, 23 met the inclusion criteria and quality standards of scientific evidence set by Downs and Black (1998). Results reveal the types and characteristics of studies and instruments used in assessing social support and cyberbullying and show the relationship between social support and cyberbullying
Functional diversification of teleost Fads2 fatty acyl desaturases occurs independently of the trophic level
The long-chain (â„C20) polyunsaturated fatty acid biosynthesis capacity of fish varies among species, with trophic level hypothesised as a major factor. The biosynthesis capacity is largely dependent upon the presence of functionally diversified fatty acyl desaturase 2 (Fads2) enzymes, since many teleosts have lost the gene encoding a Î5 desaturase (Fads1). The present study aimed to characterise Fads2 from four teleosts occupying different trophic levels, namely Sarpa salpa, Chelon labrosus, Pegusa lascaris and Atherina presbyter, which were selected based on available data on functions of Fads2 from closely related species. Therefore, we had insight into the variability of Fads2 within the same phylogenetic group. Our results showed that Fads2 from S. salpa and C. labrosus were both Î6 desaturases with further Î8 activity while P. lascaris and A. presbyter Fads2 showed Î4 activity. Fads2 activities of herbivorous S. salpa are consistent with those reported for carnivorous Sparidae species. The results suggested that trophic level might not directly drive diversification of teleost Fads2 as initially hypothesised, and other factors such as the speciesâ phylogeny appeared to be more influential. In agreement, Fads2 activities from P. lascaris and A. presbyter were similar to their corresponding phylogenetic counterparts Solea senegalensis and Chirostoma estor
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