48 research outputs found
Scaling in public transport networks
We analyse the statistical properties of public transport networks. These
networks are defined by a set of public transport routes (bus lines) and the
stations serviced by these. For larger networks these appear to possess a
scale-free structure, as it is demonstrated e.g. by the Zipf law distribution
of the number of routes servicing a given station or for the distribution of
the number of stations which can be visited from the chosen one without
changing the means of transport. Moreover, a rather particular feature of the
public transport network is that many routes service common subsets of
stations. We discuss the possibility of new scaling laws that govern intrinsic
features of such subsets.Comment: 9 pages, 4 figure
Entropic equation of state and scaling functions near the critical point in scale-free networks
We analyze the entropic equation of state for a many-particle interacting
system in a scale-free network. The analysis is performed in terms of scaling
functions which are of fundamental interest in the theory of critical phenomena
and have previously been theoretically and experimentally explored in the
context of various magnetic, fluid, and superconducting systems in two and
three dimensions. Here, we obtain general scaling functions for the entropy,
the constant-field heat capacity, and the isothermal magnetocaloric coefficient
near the critical point in scale-free networks, where the node-degree
distribution exponent appears to be a global variable and plays a
crucial role, similar to the dimensionality for systems on lattices. This
extends the principle of universality to systems on scale-free networks and
allows quantification of the impact of fluctuations in the network structure on
critical behavior.Comment: 8 pages, 4 figure
Public transport networks: empirical analysis and modeling
We use complex network concepts to analyze statistical properties of urban
public transport networks (PTN). To this end, we present a comprehensive survey
of the statistical properties of PTNs based on the data of fourteen cities of
so far unexplored network size. Especially helpful in our analysis are
different network representations. Within a comprehensive approach we calculate
PTN characteristics in all of these representations and perform a comparative
analysis. The standard network characteristics obtained in this way often
correspond to features that are of practical importance to a passenger using
public traffic in a given city. Specific features are addressed that are unique
to PTNs and networks with similar transport functions (such as networks of
neurons, cables, pipes, vessels embedded in 2D or 3D space). Based on the
empirical survey, we propose a model that albeit being simple enough is capable
of reproducing many of the identified PTN properties. A central ingredient of
this model is a growth dynamics in terms of routes represented by self-avoiding
walks.Comment: 19 pages, 23 figure
Close relationships: A study of mobile communication records
Mobile phone communication as digital service generates ever-increasing
datasets of human communication actions, which in turn allow us to investigate
the structure and evolution of social interactions and their networks. These
datasets can be used to study the structuring of such egocentric networks with
respect to the strength of the relationships by assuming direct dependence of
the communication intensity on the strength of the social tie. Recently we have
discovered that there are significant differences between the first and further
"best friends" from the point of view of age and gender preferences. Here we
introduce a control parameter based on the statistics of
communication with the first and second "best friend" and use it to filter the
data. We find that when is decreased the identification of the
"best friend" becomes less ambiguous and the earlier observed effects get
stronger, thus corroborating them.Comment: 11 pages, 7 figure
Ground truth? Concept-based communities versus the external classification of physics manuscripts
Theoretical Physic
2-Amino-4,6,7,8-tetrahydrothiopyrano[3,2-b]pyran-3-carbonitrile 5,5-dioxide VP-4535 as an antimicrobial agent selective toward methicillin‐resistant Staphylococcus aureus
The antibacterial activity of 2-amino-4,6,7,8-tetrahydrothiopyrano[3,2-b]pyran-3-carbonitrile 5,5-dioxide toward five key ESKAPE pathogenic bacteria, methicillin‐resistant Staphylococcus aureus (ATCC 43300), Escherichia coli (ATCC 25922), Klebsiella pneumonia (ATCC 700603), Acinetobacter baumannii (ATCC 19606), and Pseudomonas aeruginosa (ATCC 27853) was evaluated. The antifungal activity was studied towards pathogenic fungal strains Candida albicans (ATCC 90028) and Cryptococcus neoformans var. Grubii (ATCC 208821). Compound VP-4535 bearing 5-methylindolin-2-one motif possessed the highest antibacterial activity and excellent selectivity toward methicillin‐resistant Staphylococcus aureus but was inactive against non-resistant Staphylococcus aureus strain. The compound in therapeutic concentration was safe to human red blood cells, human lymphocytes, HaCaT, Balb/c 3T3 and HEK-293 cells
Bactericidal, protistocidal, nematodicidal properties and chemical composition of ethanol extract of Punica granatum peel
We have studied the chemical composition and antibacterial profile of ethanolic extract of Punica granatum L. (Lythraceae) on strains of microorganisms in vitro. Analysis using GC-MS showed 5-hydroxymethylfurfural (36.6%), D-sucrose (23.2%), sorbitol (6.7%), palmitic acid β-monoglyceride (5.6%), 2-furancarboxaldehyde (3.5%) and β-D-glucopyranose (3.3%) as the major components of the title extract. The experiment revealed a positive antibacterial effect of extracts obtained from P. granatum on 14 strains specifically Enterobacteriaceae microorganisms (Escherichia coli, Enterobacter aegorenеs, Proteus vulgaris, Serratia marcescens, Klebsiella pneumonia), Listeriaceae (Listeria ivanovi, L. іnnocua, L. monocytogenes) and yeasts from the family Saccharomycetaceae (Candida albicans). Our study showed that in many cases these extracts more intensively affect multi-resistant strains of microorganisms than macrolide antibiotic azithromycin and is therefore a source of molecules to be exploited in medicine or by the pharmaceutical industry. The investigated extracts of P. granatum can be recommended for further in-depth research against poly-resistant strains of the above-mentioned microorganisms. Effective drugs perform a leading role in providing stable veterinary well-being of livestock and healthcare of the population. The present study showed that the studied plant species more intensively affects multi-resistant strains of microorganisms than sodium salt of azithromycin. Lethal concentration (LC50) of ethanol extract from pomegranate for Paramecium caudatum Ehr. equaled 0.3%. Death of 100% of nematode larvae of Strongyloides papillosus (Ihle) was recorded during 24 h exposition in 20% extract of P. granatum peel