A model for the generation of social network graphs

In this paper we present and evaluate a social network model which exploits fundamental results coming from the social anthropology literature. Specifically, our model focuses on ego networks, i.e., the set of active social relationships for a given individual. The model is based on a function that correlates the level of emotional closeness of a social relationship to the time invested in it. The size of the social network is limited by the time budget a person invests in socializing. We exploit the model to define a constructive algorithm to generate synthetic social networks. Experimental results show that our model satisfies, on average, known properties of ego networks such as the size, the composition and the hierarchical structure

Dieta de pichones de cotorra Myiopsitta m. monachus (Aves: Psittacidae) en la Provincia de Buenos Aires

Dieta de pichones de Cotorra Myiopsitta m. monachus (Aves: Psittacidae) en la Provincia de Buenos Aires. El objetivo de este trabajo fue conocer la composición de la dieta aportada por los progenitores a los pichones durante su permanencia en el nido. Se analizaron los buches de 32 pichones de cotorra cuyos nidos fueron sometidos a control químico, procedentes de Gándara, Cañuelas y Villanueva (Provincia de Buenos Aires). Cada buche fue pesado con balanza analítica. Los distintos ítems integrantes de la dieta fueron separados bajo lupa binocular y pesados. La determinación se realizó en base a caracteres morfológicos externos e internos. Se observó que el 99.5% correspondió a componente vegetal, mientras que el componente mineral sólo se encontró representado en un 0.5%. En la fracción vegetal se destacaron cuatro familias siendo Asteracea y Poacea las de mayor porcentaje (96%)

The polo-like kinase 1 (PLK1) inhibitor NMS-P937 is effective in a new model of disseminated primary CD56+ acute monoblastic leukaemia

CD56 is expressed in 15–20% of acute myeloid leukaemias (AML) and is associated with extramedullary diffusion, multidrug resistance and poor prognosis. We describe the establishment and characterisation of a novel disseminated model of AML (AML-NS8), generated by injection into mice of leukaemic blasts freshly isolated from a patient with an aggressive CD56+ monoblastic AML (M5a). The model reproduced typical manifestations of this leukaemia, including presence of extramedullary masses and central nervous system involvement, and the original phenotype, karyotype and genotype of leukaemic cells were retained in vivo. Recently Polo-Like Kinase 1 (PLK1) has emerged as a new candidate drug target in AML. We therefore tested our PLK1 inhibitor NMS-P937 in this model either in the engraftment or in the established disease settings. Both schedules showed good efficacy compared to standard therapies, with a significant increase in median survival time (MST) expecially in the established disease setting (MST = 28, 36, 62 days for vehicle, cytarabine and NMS-P937, respectively). Importantly, we could also demonstrate that NMS-P937 induced specific biomarker modulation in extramedullary tissues. This new in vivo model of CD56+ AML that recapitulates the human tumour lends support for the therapeutic use of PLK1 inhibitors in AML

Location determinants of green technological entry: evidence from European regions

In this paper, we explore the spatial distribution and the location determinants of new green technology-based firms across European regions. Integrating insights from evolutionary economic geography and the literature on knowledge spillovers, we study the importance of new knowledge creation and the conditioning role played by regional technological relatedness in fostering combinatorial opportunities underlying the process of green technological entry. The analysis is based on a dataset covering over 900 NUTS3 regions for 15 European countries obtained merging economic data from ESPON-Eurostat and patent information from the PATSTAT-CRIOS database for the period 1996–2006. Our results show that the geographical distribution of green technological entry across European regions is not evenly distributed, offering evidence of spatial path dependence. In line with this, we find evidence of a significant role played by the characteristics of the regional innovation system. New green innovators are more likely to develop in regions defined by higher levels of technological activity underlying knowledge spillovers and more dynamism in technological entry. Moreover, our findings point to an inverted-U relationship between regional technological relatedness and green technological entry. Regions whose innovation activity is defined by cognitive proximity to environmental technologies support interactive learning and knowledge spillovers underlying entrepreneurship in this specific area. However, too much relatedness may cause technological lock-ins and reduce the set of combinatorial opportunities

CpG methylation potentiates pixantrone and doxorubicin-induced DNA damage and is a marker of drug sensitivity

DNA methylation is an epigenetic modification of the mammalian genome that occurs predominantly at cytosine residues of the CpG dinucleotide. Following formaldehyde activation, pixantrone alkylates DNA and particularly favours the CpG motif. Aberrations in CpG methylation patterns are a feature of most cancer types, a characteristic that may determine their susceptibility to specific drug treatments. Given their common target, DNA methylation may modulate the DNA damage induced by formaldehyde-activated pixantrone. In vitro transcription, mass spectrometry and oligonucleotide band shift assays were utilized to establish that pixantrone–DNA adduct formation was consistently enhanced 2–5-fold at discrete methylated CpG doublets. The methylation-mediated enhancement was exquisitely sensitive to the position of the methyl substituent since methylation at neighboring cytosine residues failed to confer an increase in pixantrone–DNA alkylation. Covalent modification of DNA by formaldehyde-activated doxorubicin, but not cisplatin, was augmented by neighbouring CpG methylation, indicating that modulation of binding by CpG methylation is not a general feature of all alkylators. HCT116 colon cancer cells vastly deficient in CpG methylation were 12- and 10-fold more resistant to pixantrone and doxorubicin relative to the wild-type line, suggesting that these drugs may selectively recognize the aberrant CpG methylation profiles characteristic of most tumour types