University of Siena

About: University of Siena is a education organization based out in Siena, Italy. It is known for research contribution in the topics: Population & Cancer. The organization has 12179 authors who have published 33334 publications receiving 1008287 citations. The organization is also known as: Università degli studi di Siena & Universita degli studi di Siena.

Properties of the Binary Black Hole Merger GW150914

Abstract: On September 14, 2015, the Laser Interferometer Gravitational-wave Observatory (LIGO) detected a gravitational-wave transient (GW150914); we characterise the properties of the source and its parameters. The data around the time of the event were analysed coherently across the LIGO network using a suite of accurate waveform models that describe gravitational waves from a compact binary system in general relativity. GW150914 was produced by a nearly equal mass binary black hole of $36^{+5}_{-4} M_\odot$ and $29^{+4}_{-4} M_\odot$ (for each parameter we report the median value and the range of the 90% credible interval). The dimensionless spin magnitude of the more massive black hole is bound to be $0.7$ (at 90% probability). The luminosity distance to the source is $410^{+160}_{-180}$ Mpc, corresponding to a redshift $0.09^{+0.03}_{-0.04}$ assuming standard cosmology. The source location is constrained to an annulus section of $590$ deg$^2$, primarily in the southern hemisphere. The binary merges into a black hole of $62^{+4}_{-4} M_\odot$ and spin $0.67^{+0.05}_{-0.07}$. This black hole is significantly more massive than any other known in the stellar-mass regime.

BRAF mutations in hairy-cell leukemia

Abstract: Background Hairy-cell leukemia (HCL) is a well-defined clinicopathological entity whose underlying genetic lesion is still obscure. Methods We searched for HCL-associated mutations by performing massively parallel sequencing of the whole exome of leukemic and matched normal cells purified from the peripheral blood of an index patient with HCL. Findings were validated by Sanger sequencing in 47 additional patients with HCL. Results Whole-exome sequencing identified five missense somatic clonal mutations that were confirmed on Sanger sequencing, including a heterozygous mutation in BRAF that results in the BRAF V600E variant protein. Since BRAF V600E is oncogenic in other tumors, further analyses were focused on this genetic lesion. The same BRAF mutation was noted in all the other 47 patients with HCL who were evaluated by means of Sanger sequencing. None of the 195 patients with other peripheral B-cell lymphomas or leukemias who were evaluated carried the BRAF V600E variant, including 38 patients with spl...

Mobile Landscapes: Using Location Data from Cell Phones for Urban Analysis

Abstract: The technology for determining the geographic location of cell phones and other handheld devices is becoming increasingly available. It is opening the way to a wide range of applications, collectively referred to as location-based services (LBS), that are primarily aimed at individual users. However, if deployed to retrieve aggregated data in cities, LBS could become a powerful tool for urban analysis. In this paper we aim to review and introduce the potential of this technology to the urban planning community. In addition, we present the ‘Mobile Landscapes' project: an application in the metropolitan area of Milan, Italy, based on the geographical mapping of cell phone usage at different times of the day. The results enable a graphic representation of the intensity of urban activities and their evolution through space and time. Finally, a number of future applications are discussed and their potential for urban studies and planning is assessed.

An Economic Model of Friendship: Homophily, Minorities and Segregation

Abstract: We develop a model of friendship formation that sheds light on segregation patterns observed in social and economic networks Individuals have types and see type-dependent benefits from friendships We examine the properties of a steady-state equilibrium of a matching process of friendship formation We use the model to understand three empirical patterns of friendship formation: (i) larger groups tend to form more same-type ties and fewer other-type ties than small groups, (ii) larger groups form more ties per capita, and (iii) all groups are biased towards same-type relative to demographics, with the most extreme bias coming from middle-sized groups We show how these empirical observations can be generated by biases in preferences and biases in meetings We also illustrate some welfare implications of the model