Network theory may explain the vulnerability of medieval human settlements to the Black Death pandemic

Epidemics can spread across large regions becoming pandemics by flowing along transportation and social networks. Two network attributes, transitivity (when a node is connected to two other nodes that are also directly connected between them) and centrality (the number and intensity of connections with the other nodes in the network), are widely associated with the dynamics of transmission of pathogens. Here we investigate how network centrality and transitivity influence vulnerability to diseases of human populations by examining one of the most devastating pandemic in human history, the fourteenth century plague pandemic called Black Death. We found that, after controlling for the city spatial location and the disease arrival time, cities with higher values of both centrality and transitivity were more severely affected by the plague. A simulation study indicates that this association was due to central cities with high transitivity undergo more exogenous re-infections. Our study provides an easy method to identify hotspots in epidemic networks. Focusing our effort in those vulnerable nodes may save time and resources by improving our ability of controlling deadly epidemics

Comparison of Synchrotron X-Ray Microanalysis With Electron and Proton Microscopy for Individual Particle Analysis

This paper is concerned with the evaluation of the use of synchrotron/radiation induced x-ray fluorescences ({mu}-SRXRF) as implemented at two existing X-ray microprobes for the analysis of individual particles. As representative environmental particulates, National Institutes of Science and Technology (NIST) K227, K309, K441 and K961 glass microspheres were analyzed using two types of X-ray micro probes: the white light microprobe at beamline X26A of the monochromatic (15 keV) X-ray microprobe at station 7.6 of the SRS. For reference, the particles were also analyzed with microanalytical techniques more commonly employed for individual particles analysis such as EPMA and micro-PIXE

First microdosimetric measurements with a TEPC based on a gem

A new type of mini multi-element tissue-equivalent proportional counter (TEPC) based on a gas electron multiplier (GEM) has been designed and constructed. This counter is in particular suitable to be constructed with a small sensitive volume so that it can be used for microdosimetry in intense pulsed radiation fields to measure the microdosimetric spectrum in the beam of, for instance, a clinical linear accelerator. The concept lends itself also for a mini multi-element version of the counter to be used for applications in which a high sensitivity is required. In this paper, we present the first microdosimetric measurements of this novel counter exposed to a 14 MeV monoenergetic neutron beam and a californium (Cf-252) source for a counter cavity diameter of 1.8 mm simulating 1.0 mum tissue site size. The measured spectra showed an excellent agreement with spectra from the literature. The specific advantages of the TEPC-GEM are discussed

Study of TL glow curves of YPO4 double doped with lanthanide ions

Thermoluminescence (TL) emission spectra and TL glow curves of samples of YPO4:Ce3+, Ln(3+) (Ln(3+) = Pr3+ Nd3+, Sm3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+) and YPO4:Tb3+, Ln(3+) (Ln(3+) = Nd3+, Ho3+, Dy3+, Sm3+,Tm3+) were measured in order to investigate the nature of the trapping centres and to compare the lanthanide energy levels in the band gap with a predictive energy level scheme developed earlier. The nature of the trapping centres agrees with that predicted by the energy level scheme. The hole accepting dopants (Ce3+ and Tb3+) act as recombination centres emitting the characteristic Ce3+ or Tb3+ emission. The electron accepting codopants produce glow peaks at different temperatures. The sequence of glow peaks maxima of the electron accepting codopants appears exactly as predicted by the level scheme of the divalent Ln ions. Trap depths, determined with the various heating rate method, follow the trend as predicted by the level scheme but were found systematically shallower. This can be explained by the uncertainty in the energy level predictions and/or tunnelling of the charge carriers from codopant to dopant and the presence of excited states of the divalent Ln ions in the band gap which makes alternative recombination pathways possible. In general it can be concluded that the energy level scheme is a powerful tool to interpret and predict all kinds of TL phenomena