Reinventing the Triangles: Rule of Thumb for Assessing Detectability

Statistical significance of network clustering has been an unresolved problem since it was observed that community detection algorithms produce false positives even in random graphs. After a phase transition between undetectable and detectable cluster structures was discovered, the connection between spectra of adjacency matrices and detectability limits were shown, and both were calculated for a wide range of networks with arbitrary degree distributions and community structure. In practice the full eigenspectrum is not known, and whether a given network has any communities within detectability regime cannot be easily established. Based on the global clustering coefficient we construct a criterion telling whether in an undirected, unweighted network there is some/no detectable community structure, or if the network is in a transient regime. The method is simple and faster than methods involving bootstrapping.Comment: 6 pages, 4 figures. Accepted to IEEE Computer Society. Presented at The 4th International Workshop on Complex Networks and their Applications, November 23-27, 2015 Bangkok, Thailan

Developing Diplomats: Comparing Form and Culture Across Diplomatic Services, PRP 194

This study is a detailed and focused effort to broaden how we understand and conceptualize the recruitment, training, and development of professional diplomats in the twenty-first century. The goal is not to criticize processes in different countries, but to create a common foundation for comparing, learning, and even integrating training and career development models across nations.Public Affair

Maximal Entropy Random Walk: solvable cases of dynamics

We focus on the study of dynamics of two kinds of random walk: generic random walk (GRW) and maximal entropy random walk (MERW) on two model networks: Cayley trees and ladder graphs. The stationary probability distribution for MERW is given by the squared components of the eigenvector associated with the largest eigenvalue \lambda_0 of the adjacency matrix of a graph, while the dynamics of the probability distribution approaching to the stationary state depends on the second largest eigenvalue \lambda_1. Firstly, we give analytic solutions for Cayley trees with arbitrary branching number, root degree, and number of generations. We determine three regimes of a tree structure that result in different statics and dynamics of MERW, which are due to strongly, critically, and weakly branched roots. We show how the relaxation times, generically shorter for MERW than for GRW, scale with the graph size. Secondly, we give numerical results for ladder graphs with symmetric defects. MERW shows a clear exponential growth of the relaxation time with the size of defective regions, which indicates trapping of a particle within highly entropic intact region and its escaping that resembles quantum tunneling through a potential barrier. GRW shows standard diffusive dependence irrespective of the defects.Comment: 13 pages, 6 figures, 24th Marian Smoluchowski Symposium on Statistical Physics (Zakopane, Poland, September 17-22, 2011

Materials to the Polish flora in the Herbarium of the University of Łódź. Part XX - the genus Potentilla L. (rosaceae)

The study contains the revision of the herbarium specimens of the genus Potentilla (Rosaceae) preserved in Herbarium Universitatis Lodziensis - Department of Botany (LOD). The list of species consists of 28 taxa of Potentilla found on 605 localities althogether.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę

A simple non-equilibrium, statistical-physics toy model of thin-film growth

We present a simple non-equilibrium model of mass condensation with Lennard-Jones interactions between particles and the substrate. We show that when some number of particles is deposited onto the surface and the system is left to equilibrate, particles condense into an island if the density of particles becomes higher than some critical density. We illustrate this with numerically obtained phase diagrams for three-dimensional systems. We also solve a two-dimensional counterpart of this model analytically and show that not only the phase diagram but also the shape of the cross-sections of three-dimensional condensates qualitatively matches the two-dimensional predictions. Lastly, we show that when particles are being deposited with a constant rate, the system has two phases: a single condensate for low deposition rates, and multiple condensates for fast deposition. The behaviour of our model is thus similar to that of thin film growth processes, and in particular to Stranski-Krastanov growth.Comment: 26 pages, 16 figure

Achene surface features in Potentilla subarenaria Borbás ex Zimmeter and P. intermedia L. non Wahlenb. (Rosaceae)

Achenes morphology in Potentilla L., i.e. P. subarenaria Borbás ex Zimmeter and P. intermedia L. nonWahlenb. was examined with stereoscope and scanning electron microscope (SEM). Achenes of these taxa varied in shape, size, colour, the surface sculpture and in the dimensions of dorsal ridge and ribs. SEM analyses allowed distinguishing two morphological types of seed coats pattern: ruminate-reticulate sculpture due to well preserved epidermal cells in P. subarenaria and tuberculate sculpture in P. intermedia. The main taxonomic features of these two taxa are: the microstructure, size, shape and colour of achenes

Field Thicket m the Neighbourhood of the Village of Olsztyn in the Northern Part of the Częstochowska Upland

The thicket communities grow in the fields in the neighbourhood of the village of Olsztyn near the town of Częstochowa. They include 235 species of vascular plants and 15 taxa of mosses. Two thicket associations of the class Rhamno-Prunetea are described.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 zostało dofinansowane ze środków MNiSW w ramach działalności upowszechniającej naukę

Adaptation of the "Herbarium" Computer DataBase to Archiving and Analysis of Floristic Data

The aim of the study was to present "Herbarium" computer database. The basic goal of construction of the database was gathering and analysing of archival and contemporary floristic data referring to the area of Central Poland. Registered information considers the stands and characteristic biological and ecological traits of particular taxa. Life forms, indices of ecological requirements, the phytogeographical elements, protection and threat status are among them. The database enables the presentation of geographical distribution of taxa in the area of Central Poland with the cartogram method based on the grid of 2 km2 according to the Distribution Atlas of Vascular Plants in Poland (Atpol)