Stationary distribution and cover time of sparse directed configuration models

We consider sparse digraphs generated by the configuration model with given in-degree and out-degree sequences. We establish that with high probability the cover time is linear up to a poly-logarithmic correction. For a large class of degree sequences we determine the exponent \u3b3 651 of the logarithm and show that the cover time grows as nlog\u3b3(n), where n is the number of vertices. The results are obtained by analysing the extremal values of the stationary distribution of the digraph. In particular, we show that the stationary distribution \u3c0 is uniform up to a poly-logarithmic factor, and that for a large class of degree sequences the minimal values of \u3c0 have the form 1nlog1 12\u3b3(n), while the maximal values of \u3c0 behave as 1nlog1 12\u3ba(n) for some other exponent \u3ba 08[0,1]. In passing, we prove tight bounds on the diameter of the digraphs and show that the latter coincides with the typical distance between two vertices

Cutoff for the Averaging process on the hypercube and complete bipartite graphs

We consider the averaging process on a graph, that is the evolution of a mass distribution undergoing repeated averages along the edges of the graph at the arrival times of independent Poisson processes. We establish cutoff phenomena for both the $L^1$ and $L^2$ distance from stationarity when the graph is a discrete hypercube and when the graph is complete bipartite. Some general facts about the averaging process on arbitrary graphs are also discussed.Comment: 30 pages. Comments are welcom

Per ignobile vulgus: una descrizione della sifilide nel De podagra di Antonio Galateo

Il De podagra, unica opera medica del Galateo conservata dalla tradizione, occupa un posto di rilievo all’interno della produzione dell’umanista salentino. In particolare, desta notevole interesse l’ultima parte: ci troviamo, infatti, di fronte ad una delle prime descrizioni della sifilide, la cui epidemia in quegli anni stava decimando la popolazione europea. Il brano, che potrebbe essere frutto di un intervento seriore, pare aprire un nuovo campo di ricerca che però il Galateo non esplorò mai, forse perché travolto dalla caduta del Regno aragonese.The De podagra, Galateo's only medical work preserved by tradition, occupies an important place within the production of the humanist from Salento. In particular, the last part is of considerable interest: we are, in fact, faced with one of the first descriptions of syphilis, the epidemic which was decimating the European population in those years. The passage, which could be the result of a later intervention, seems to open up a new field of research that Galateo never explored, perhaps because he was overwhelmed by the fall of the Aragonese kingdom

Thin film differential photosensor for reduction of temperature effects in lab-on-chip applications

This paper presents a thin film structure suitable for low-level radiation measurements in lab-on-chip systems that are subject to thermal treatments of the analyte and/or to large temperature variations. The device is the series connection of two amorphous silicon/amorphous silicon carbide heterojunctions designed to perform differential current measurements. The two diodes experience the same temperature, while only one is exposed to the incident radiation. Under these conditions, temperature and light are the common and differential mode signals, respectively. A proper electrical connection reads the differential current of the two diodes (ideally the photocurrent) as the output signal. The experimental characterization shows the benefits of the differential structure in minimizing the temperature effects with respect to a single diode operation. In particular, when the temperature varies from 23 to 50 _C, the proposed device shows a common mode rejection ratio up to 24 dB and reduces of a factor of three the error in detecting very low-intensity light signals

Sport Entrepreneurship: A Synthesis of Existing Literature and Future Perspectives

Sport entrepreneurship is progressively emerging as an extremely significant stream of research. Accordingly, scholars are progressively assessing how sportspeople tend to have higher entrepreneurial orientation and intentions than the average. In a similar fashion, scholars have also observed how sport-related entrepreneurial ventures can have a positive effect on community development. This notwithstanding, this literature stream is still fragmented, lacks a proper systematization, and needs an identification of its intellectual structure and research themes. Hereby, we performed a bibliometric analysis on 86 papers and a systematic literature review on the most influential papers belonging to the pertinent literature. Results show that a 4-cluster structure exists for sport entrepreneurship: its theoretical definitions and internal factors fostering it (cluster 1), environmental factors which may foster it (cluster 2), pedagogical approaches and education (cluster 3), and finally its impacts, especially in terms of community development and social benefits (cluster 4). From these findings, a framework to help both scholars and practitioners approaching the topic was developed

Internationalisation of firms from Central and Eastern Europe: a systematic literature review

Purpose: The objective of this article is to provide a systematic review of the literature addressing internationalisation of firms from Central and Eastern Europe (CEE). Design/methodology/approach: This article presents an inter-disciplinary systematic review of literature about the internationalisation of firms from CEE. Findings: Three different clusters of research were identified. In the "Internationalisation Processes" cluster, containing many comparative studies, the focus is on specific approaches adopted by local firms in the process of internationalisation. One of the leitmotivs is the dichotomy between hostile home-country factors that create the need for internationalisation and market- seeking motives that guide the search for international expansion. The "Internationalisation Variables" cluster aims to explain the reasons of success or failure of internationalisation processes and strategies; this cluster focuses on possible facilitating or hindering aspects experienced by CEE firms and one often-cited element is the firm's network. Finally, the "Internationalisation Outcomes" cluster assumes a reverse approach when compared to the other two clusters. Indeed, the internationalisation phenomenon can also be studied in terms of its effect on the firm; the elements sought in these types of studies are both potential benefits and risks associated with internationalisation in CEE countries. The latter category in particular gives rise to interesting questions for future research. Originality/value: Given that large, developed economies tend to receive much academic interest, and that smaller transitional economies are not always adequately represented in the scientific discussion, this article contributes to the literature on internationalisation