2,342 research outputs found
The anomaly flow on nilmanifolds
We study the Anomaly flow on 2-step nilmanifolds with respect to any Hermitian connection in the Gauduchon line. In the case of flat holomorphic bundle, the general solution to the Anomaly flow is given for any initial invariant Hermitian metric. The solutions depend on two constants K1 and K2, and we study the qualitative behaviour of the Anomaly flow in terms of their signs, as well as the convergence in Gromov–Hausdorff topology. The sign of K1 is related to the conformal invariant introduced by Fu, Wang and Wu. In the non-flat case, we find the general evolution equations of the Anomaly flow under certain initial assumptions. This allows us to detect non-flat solutions to the Hull-Strominger-Ivanov system on a concrete nilmanifold, which appear as stationary points of the Anomaly flow with respect to the Strominger-Bismut connection. © 2021, The Author(s), under exclusive licence to Springer Nature B.V
A comprehensive study of electric, thermoelectric and thermal conductivities of Graphene with short range unitary and charged impurities
Motivated by the experimental measurement of electrical and hall
conductivity, thermopower and Nernst effect, we calculate the longitudinal and
transverse electrical and heat transport in graphene in the presence of unitary
scatterers as well as charged impurities. The temperature and carrier density
dependence in this system display a number of anomalous features that arise due
to the relativistic nature of the low energy fermionic degrees of freedom. We
derive the properties in detail including the effect of unitary and charged
impurities self-consistently, and present tables giving the analytic
expressions for all the transport properties in the limit of small and large
temperature compared to the chemical potential and the scattering rates. We
compare our results with the available experimental data. While the qualitative
variations with temperature and density of carriers or chemical potential of
all transport properties can be reproduced, we find that a given set of
parameters of the impurities fits the Hall conductivity, Thermopower and the
Nernst effect quantitatively but cannot fit the conductivity quantitatively. On
the other hand a single set of parameters for scattering from Coulomb
impurities fits conductivity, hall resistance and thermopower but not Nernst
The GRB 030328 host: another case of a blue starburst galaxy
We present for the first time the detection of the GRB 030328 host galaxy in
four optical bands equivalent to UBRI. The host galaxy spectral energy
distribution is consistent with a low extinction (E(B-V) < 0.21) starburst
galaxy. The restframe B-band magnitude of the host is M_B ~ -20.4Comment: 4 pages, 2 figures, accepted for publication in Il nuovo cimento (4th
Workshop Gamma-Ray Bursts in the Afterglow Era, Rome, 18-22 October 2004
CDS wide slit time-series of EUV coronal bright points
Wide slit (90" x 240" ) movies of four Extreme Ultraviolet coronal bright points (BPs) obtained with the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SoHO) have been inspected. The wavelet analysis of the He I 584.34 Å, O V 629.73 Å and Mg VII/IX 368 Å time-series confirms the oscillating nature of the BPs, with periods ranging between 600 and 1100 s. In one case we detect periods as short as 236 s. We suggest that these oscillations are the same as those seen in the chromospheric network and that a fraction of the network bright points are most likely the cool footpoints of the loops comprising coronal bright points. These oscillations are interpreted in terms of global acoustic modes of the closed magnetic structures associated with BPs
Iron accumulates in the primate choroid of the eye with aging as revealed with synchrotron X-ray fluorescence microscopy
Aging leads to an increase in iron-loaded cellular structures in the choroid of the eye. This study was carried out to determine the distribution and content of iron, zinc and copper in the macular retina, choroid and retrobulbar optic nerve of young (4–5 years, n = 3) and aged (15–16 years, n = 5) male non-human primates, Macaca fascicularis, whose ocular anatomy is similar to humans. Thirty μm-thick tissue sections were analysed with synchrotron X-ray fluorescence and stained histologically for iron deposition. Quantitative measurements showed high levels of iron, zinc and copper in the choroid and retinal pigment epithelium in the macular area and arachnoid layer in the retrobulbar optic nerve. In aged animals compared to young ones, there was an increase in iron in the choroid with larger deposits and iron-loaded cellular structures. Iron-accumulation within these cellular structures may contribute to choroidal function impairment in aging and age-related macular degeneration
Polyhedral study of the 2-dominating set polytope of cycles and cactus graphs
Domination and its variations arise in many applications, in particular in those involving strategic placement of items at vertices of a network. For general graphs these problems are NP-hard, however, domination in graphs has been shown to be polynomially solvable in several graph classes. In this work we consider a generalization of this problem called k-domination in graphs.Sociedad Argentina de Informática e Investigación Operativ
Is Small Perfect? Size Limit to Defect Formation in Pyramidal Pt Nanocontacts
We report high resolution transmission electron microscopy and ab initio
calculation results for the defect formation in Pt nanocontacts (NCs). Our
results show that there is a size limit to the existence of twins (extended
structural defects). Defects are always present but blocked away from the tip
axes. The twins may act as scattering plane, influencing contact electron
transmission for Pt NC at room temperature and Ag/Au NC at low temperature.Comment: 4 pages, 3 figure
Polyhedral study of the 2-dominating set polytope of cycles and cactus graphs
Domination and its variations arise in many applications, in particular in those involving strategic placement of items at vertices of a network. For general graphs these problems are NP-hard, however, domination in graphs has been shown to be polynomially solvable in several graph classes. In this work we consider a generalization of this problem called k-domination in graphs.Sociedad Argentina de Informática e Investigación Operativ
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