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

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

A young stellar environment for the superluminous supernova PTF12dam

The progenitors of super luminous supernovae (SLSNe) are still a mystery. Hydrogen-poor SLSN hosts are often highly star-forming dwarf galaxies and the majority belongs to the class of extreme emission line galaxies hosting young and highly star-forming stellar populations. Here we present a resolved long-slit study of the host of the hydrogen-poor SLSN PTF12dam probing the kpc environment of the SN site to determine the age of the progenitor. The galaxy is a "tadpole" with uniform properties and the SN occurred in a star-forming region in the head of the tadpole. The galaxy experienced a recent star-burst superimposed on an underlying old stellar population. We measure a very young stellar population at the SN site with an age of ~3 Myr and a metallicity of 12+log(O/H)=8.0 at the SN site but do not observe any WR features. The progenitor of PTF12dam must have been a massive star of at least 60 M_solar and one of the first stars exploding as a SN in this extremely young starburst.Comment: submitted to MNRAS letters. 5 pages, 3 figures, supplementary material: 2 figures, 2 table

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

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

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

The Classification of Highly Supersymmetric Supergravity Solutions

The spinorial geometry method is an effective method for constructing systematic classifications of supersymmetric supergravity solutions. Recent work on analysing highly supersymmetric solutions in type IIB supergravity using this method is reviewed [arXiv:hep-th/0606049, arXiv:0710.1829]. It is shown that all supersymmetric solutions of IIB supergravity with more than 28 Killing spinors are locally maximally supersymmetric.Comment: 23 pages, latex. To appear in the proceedings of the Special Metrics and Supersymmetry conference at Universidad del Pais Vasco, May 2008. References correcte

The role of structural evolution on the quantum conductance behavior of gold nanowires during stretching

Gold nanowires generated by mechanical stretching have been shown to adopt only three kinds of configurations where their atomic arrangements adjust such that either the [100], [111] or [110] zone axes lie parallel to the elongation direction. We have analyzed the relationship between structural rearrangements and electronic transport behavior during the elongation of Au nanowires for each of the three possibilities. We have used two independent experiments to tackle this problem, high resolution transmission high resolution electron microscopy to observe the atomic structure and a mechanically controlled break junction to measure the transport properties. We have estimated the conductance of nanowires using a theoretical method based on the extended H\"uckel theory that takes into account the atom species and their positions. Aided by these calculations, we have consistently connected both sets of experimental results and modeled the evolution process of gold nanowires whose conductance lies within the first and third conductance quanta. We have also presented evidence that carbon acts as a contaminant, lowering the conductance of one-atom-thick wires.Comment: 10 page

Identifying extreme COVID-19 mortality risks in English small areas: a disease cluster approach

The COVID-19 pandemic is having a huge impact worldwide and has highlighted the extent of health inequalities between countries but also in small areas within a country. Identifying areas with high mortality is important both of public health mitigation in COVID-19 outbreaks, and of longer term efforts to tackle social inequalities in health. In this paper we consider different statistical models and an extension of a recent method to analyze COVID-19 related mortality in English small areas during the first wave of the epidemic in the first half of 2020. We seek to identify hotspots, and where they are most geographically concentrated, taking account of observed area factors as well as spatial correlation and clustering in regression residuals, while also allowing for spatial discontinuities. Results show an excess of COVID-19 mortality cases in small areas surrounding London and in other small areas in North-East and and North-West of England. Models alleviating spatial confounding show ethnic isolation, air quality and area morbidity covariates having a significant and broadly similar impact on COVID-19 mortality, whereas nursing home location seems to be slightly less important.This work has been supported by Projects MTM2017-82553-R (AEI/FEDER, UE) and Project PID2020-113125RB-I00/MCIN/AEI/10.13039/501100011033). Funding Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature