11,281 research outputs found
Exceptional theories
We present a new construction of four dimensional theories,
given by M5 branes wrapping a in an M-theory U-fold background. The
resulting setup generalizes the one used in the usual class
construction of four dimensional theories by using an extra discrete symmetry
on the M5 worldvolume. Together with the M-theory U-fold description of
-type six-dimensional SCFTs, this allows to construct new, exceptional,
theories.Comment: v2: Minor modifications, version to appear in JHE
AGN spiral galaxies in groups: effects of bars
We explore properties of barred active spiral galaxies in groups selected
from the SDSS-DR7, with the aim of assessing the effects of bars on AGN and the
role of the high density environment. We identified barred active galaxies that
reside in groups from SDSS-DR7 group catalog. To provide a suitable
quantification of the effects of bars, a reliable control sample of unbarred
active galaxies in high density environments with similar redshift, magnitude,
morphology, and bulge size distributions was constructed. We found that the
fraction of barred AGN galaxies in groups (~ 38 %) is higher than those in the
total barred AGN sample ( ~ 28 %), indicating that AGN spiral galaxies in
groups are more likely to be barred than those in the field. We also found that
barred AGN galaxies are more concentrated towards the group centers than the
other unbarred AGN group members. In addition, barred AGN host galaxies show an
excess of population dominated by red colors suggesting that bars produce an
importanteffect on galaxy colors of AGN hosts. The host groups of the barred
AGN exhibit a larger fraction of red colors than the host groups of the
corresponding unbarred active galaxies. Color-magnitude relations of both host
groups of AGN differ significantly: the host group colors of barred active
galaxies display distributions spreading toward red populations, with respect
to the host groups of the unbarred AGN objects. Barred active galaxies show an
excess of nuclear activity compared to galaxies without bars. We found that
barred active galaxies located farther from the group-center have stronger
Lum[OIII]. Our findings suggest that the efficiency of bars to transport
material towards the more central regions of the AGN galaxies in high density
environments reveals an important dependence on the localization of objects
within the group and on the host group colors.Comment: 10 pages, 10 figures. Accepted for Astronomy & Astrophysic
Thermodynamic, economic and environmental assessment of energy systems including the use of gas from manure fermentation in the context of the Spanish potential
One of the prospective technologies that can be used for energy generation in distributed systems is based on biogas production, usually involving fermentation of various types of biomass and waste. This article aims to bring novelty on the analysis of this type of systems, joining together thermodynamic, economic and environmental aspects for a cross-cutting evaluation of the proposed solutions. The analysis is made for Spain, for which such a solution is very promising due to availability of the feedstock. A detailed simulation model of the proposed system in two different cases was built in Aspen Plus software and Visual Basic for Applications. Case 1 involves production of biogas in manure fermentation process, its upgrading (cleaning and removal of CO2 from the gas) and injection to the grid. Case 2 assumes combustion of the biogas in gas engine to produce electricity and heat that can be used locally and/or sold to the grid. Thermodynamic assessment of these two cases was made to determine the most important parameters and evaluation indices. The results served as input values for the economic analysis and environmental evaluation through Life Cycle Assessment of the energy systems. The results show that the analysed technologies have potential to produce high-value products based on low-quality biomass. Economic evaluation determined the break-even price of biomethane (Case 1) and electricity (Case 2), which for the nominal assumptions reach the values of 16.77 €/GJ and 28.92 €/GJ, respectively. In terms of environmental assessment the system with the use of biogas in gas engine presents around three times better environmental profile than Case 1 in the two categories evaluated, i.e., carbon and energy footprint.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie SkĹ‚odowska-Curie grant agreement No 799439. Dr. MartĂn-Gamboa states that thanks are due to FCT/MCTES for the financial support to CESAM (UID/AMB/50017/2019), through national funds
Quantum Singular Value Decomposer
We present a variational quantum circuit that produces the Singular Value
Decomposition of a bipartite pure state. The proposed circuit, that we name
Quantum Singular Value Decomposer or QSVD, is made of two unitaries
respectively acting on each part of the system. The key idea of the algorithm
is to train this circuit so that the final state displays exact output
coincidence from both subsystems for every measurement in the computational
basis. Such circuit preserves entanglement between the parties and acts as a
diagonalizer that delivers the eigenvalues of the Schmidt decomposition. Our
algorithm only requires measurements in one single setting, in striking
contrast to the settings required by state tomography. Furthermore, the
adjoints of the unitaries making the circuit are used to create the
eigenvectors of the decomposition up to a global phase. Some further
applications of QSVD are readily obtained. The proposed QSVD circuit allows to
construct a SWAP between the two parties of the system without the need of any
quantum gate communicating them. We also show that a circuit made with QSVD and
CNOTs acts as an encoder of information of the original state onto one of its
parties. This idea can be reversed and used to create random states with a
precise entanglement structure.Comment: 6 + 1 pages, 5 figure
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