3,286 research outputs found
A PBW basis for Lusztig's form of untwisted affine quantum groups
Let be an untwisted affine Kac-Moody algebra over the field
, and let be the associated quantum enveloping
algebra; let be the Lusztig's integer form of , generated by -divided powers of Chevalley
generators over a suitable subring of . We prove a
Poincar\'e-Birkhoff-Witt like theorem for ,
yielding a basis over made of ordered products of -divided powers of
suitable quantum root vectors.Comment: 22 pages, AMS-TeX C, Version 2.1c. This is the author's final
version, corresponding to the printed journal versio
Mobile security with location-aware role-based access control
This paper describes how location-aware Role-Based Access
Control (RBAC) can be implemented on top of the Geographically eXtensible
Access Control Markup Language (GeoXACML). It furthermore
sketches how spatial separation of duty constraints (both static and dynamic)
can be implemented using GeoXACML on top of the XACML
RBAC profile. The solution uses physical addressing of geographical locations
which facilitates easy deployment of authorisation profiles to the
mobile device. Location-aware RBAC can be used to implement location
dependent access control and also other security enhancing solutions on
mobile devices, like location dependent device locking, firewall, intrusion
prevention or payment anti-fraud systems
The candidate filament close to the 3C295 galaxy cluster: optical and X-ray spectroscopy
We present a detailed analysis of the overdensity of X-ray sources colse to
the 3C 295 galaxy cluster (z=0.46) to assess whether it is associated with a
filament of the large-scale structure of the Universe. We obtained optical
spectra of the optical counterparts of eleven sources associated with the
filament, finding that one is at z=0.474. This is a type 1 AGN at 1.5 arcmin
from the cluster center. We found three more sources with a redshift in the
range 0.37 - 0.53. We extracted the stacked X-ray spectrum of 47 X-ray sources
belonging to the putative filament. We found a significant narrow (at the
resolution of the Chandra ACIS-I) line at E ~ 4.4 keV, the energy of the iron
Kalpha line at the redshift of the cluster. The detection of this line is
confirmed at a confidence level of better than 3sigma and its energy is
constrained to be in the range 6.2--6.47 (at a 90% confidence level), excluding
an identification with the 6.7 helium-like iron line from the hot cluster ICM
at better than 4 sigma. We conclude that the detection of the redshifted line
is a strong indication that at least several of the excess sources lie at z ~
0.46 and that AGNs are efficient tracers of the ``filament'' connected with the
central cluster of galaxies.Comment: 7 Pages 9 .ps figures, A&A in pres
High Polymorphism for Forage Production of \u3ci\u3eLotus corniculatus Sn\u3c/i\u3e Transformants
Transgenic plants obtained from transformation of one individual of Lotus corniculatus with the maize gene Sn, a transactivator of anthocyanin pathway, were analysed for the expression of the transgene and for the accumulation of condensed tannins. A great variability was observed for these two traits. Some extreme individuals were clonally propagated and analysed for rooting ability and plant growth. Unexpectedly, a strong correlation between condensed tannin level, rooting ability and plant growth was observed. These results are discussed in order to explore new strategies to increase plant productivity in forage legumes
AE Aurigae: first detection of non-thermal X-ray emission from a bow shock produced by a runaway star
Runaway stars produce shocks when passing through interstellar medium at
supersonic velocities. Bow shocks have been detected in the mid-infrared for
several high-mass runaway stars and in radio waves for one star. Theoretical
models predict the production of high-energy photons by non-thermal radiative
processes in a number sufficiently large to be detected in X-rays. To date, no
stellar bow shock has been detected at such energies. We present the first
detection of X-ray emission from a bow shock produced by a runaway star. The
star is AE Aur, which was likely expelled from its birthplace by the encounter
of two massive binary systems and now is passing through the dense nebula IC
405. The X-ray emission from the bow shock is detected at 30" to the northeast
of the star, coinciding with an enhancement in the density of the nebula. From
the analysis of the observed X-ray spectrum of the source and our theoretical
emission model, we confirm that the X-ray emission is produced mainly by
inverse Compton upscattering of infrared photons from dust in the shock front.Comment: Accepted for publication in the Astrophysical Journal with number
ApJ, 757, L6. Four figure
Alterations in rhinosinusal homeostasis in a sportive population: our experience with 106 athletes
The aim of the present work was to analyse the alterations of rhino-sinusal physiology in 106 professional athletes (swimmers, skiers, boxers and runners) using objective rhinological methods. Every athlete underwent an accurate anamnesis, a complete objective ORL evaluation, an active anterior rhinomanometry, an acoustic rhinometry and an evaluation of mucociliary transport time (MCTt). Skiers were also submitted to a nasal decongestion test (NDT). In swimmers, the mean MCTt was 27.4+/-4.97 min (normal value: 13+/-3 min; P<0.0001). The average MCTt for the skier group was 19.58+/-1.92 min ( P<0.0001); the mean value of total basal nasal resistance was 0.37+/-0.05 Pa/ml per s (normal value =0.25 Pa/ml per s; P<0.001). After NDT, total nasal resistance was 0.18+/-0.02 Pa/ml per s. In the group of boxers, the total mean nasal resistance was 0.64+/-0.05 Pa/ml per s ( P<0.001); the mean cross-sectional area at the nasal valve level was 0.57+/-0.04 cm(2) (normal value =0.55+/-0.05 cm(2)) and at the inferior turbinate level 0.83+/-0.05 cm(2) (normal value =0.4+/-0.04 cm(2); P<0.001); the TMC average time was 27.35+/-2.21 min ( P<0.0001). Finally, for the runners, the mean MCT time was 20.56+/-2.35 min ( P<0.001). Knowing the alterations of the physiological nasal respiration is of extreme importance to develop a correct and timely therapeutic approach to be able to restore rhino-sinusal homeostasis. Athletes, in fact, need the earliest therapeutic aid in order to avoid the interference of prolonged rhino-sinusal alterations with their performance and also to avoid a more serious clinical situation concerning the inferior airways
Nasal obstruction and headache. A real correlation?
to evaluate the relationships between headache and nasal obstruction or nasal allergy on a group of Italian school children
- …