65 research outputs found
Antimagnetic rotation and sudden change of electric quadrupole transition strength in 143Eu
Lifetimes of the states in the quadrupole structure in 143Eu have been
measured using the Doppler shift attenuation method as well as parity of the
states in the sequence has been firmly identified from polarization measurement
using the Indian National Gamma Array. The decreasing trends of the deduced
quadrupole transition strength B(E2) with spin, along with increasing J (2)
/B(E2) values before band crossing, conclusively establish the origin of these
states as arising out of antimagnetic rotation. The abrupt increase in the
B(E2) values after the band crossing in the quadrupole band, a novel feature
observed in the present experiment, may indicates the crossing of different
shears configurations resulting in re-opening of shears structure. The results
are well reproduced by numerical calculation within the framework of
semi-classical geometric model.Comment: 6 pages, 4 postscript figure
Isolation and characterization of metal-resistant bacterial strain from wastewater and evaluation of its capacity in metal-ions removal using living and dry bacterial cells
Implementing opportunistic spectrum access in LTE-Advanced
Long term evolution advanced (LTE-A) has emerged as a promising mobile broadband access technology aiming to cope with the increasing traffic demand in wireless networks. However, the enhanced spectral efficiency offered by LTE-A may become futile without a better management of scarce and overcrowded electromagnetic spectrum. In this sense, cognitive radio (CR) has been proposed as a potential solution to the problem of spectrum scarcity. Among all the mechanisms provided by CR, opportunistic spectrum access (OSA) aims at a dynamic and seamless use of certain licensed bands provided the licensee is not harmfully affected. This operation requires spectral awareness in order to avoid interferences with licensed systems. In spite of implementing some spectrum sensing mechanisms, LTE-A technology lacks other tools that are needed in order to improve the knowledge of the radio environment. This work studies the adoption of a Geo-located data base (Geo-DB) that cooperatively retrieves and maintains information regarding the location of unutilized portions of spectrum potentially available for OSA. Moreover, the potential benefit of this LTE-compliant OSA solution is evaluated using a calibrated simulation tool, by which numerical results allow us to optimally configure the system and show that the proposed opportunistic system is able to significantly improve its performance.The authors would like to thank the funding received from the Ministerio de Ciencia e Innovacion within the Project number TEC2011-27723-C02-02 and from the Ministerio de Industria, Turismo y Comercio TSI-020100-2011-266 funds. This article had been written in the framework of the CELTIC project CP08-001 COMMUNE. Study by X. Gelabert is funded by the BP-DGR 2010 scholarship (ref. 00192). 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