1,721,009 research outputs found
No genotoxicity of a new nickel-free stainless steel
No full textInt J Artif Organs. 2005 Jan;28(1):58-65.
No genotoxicity of a new nickel-free stainless steel.
Montanaro L, Cervellati M, Campoccia D, Prati C, Breschi L, Arciola CR.
Research Laboratory on Biocompatibility of Implant Materials, Rizzoli Orthopedic Institute, Bologna, Italy. [email protected]
Stainless steel is a metallic alloy largely employed in orthopedics,
maxillofacial surgery and orthodontic therapy. However, the presence in its composition of a high quantity of nickel, an agent known to trigger toxic, allergic and cancerogenous responses in humans, is cause of some concern. In this study, we have investigated the in vitro mutagenicity and genotoxicity of a
new nickel-free stainless steel, namely P558, in comparison to the conventional stainless steel AISI 316L. The cytogenetic effects were evaluated by studying the frequency of Sister Chromatid Exchanges (SCE) and chromosomal aberrations. Ames test was performed to detect the mutagenic activity. Both P558 and AISI
316L did not cause any significant increase in the average number of SCE and in chromosomal aberrations, either with or without metabolic activation. Furthermore, the Ames test showed that the extracts of both P558 and of AISI 316L are not mutagenic. Overall, these findings prove that P558 is devoid of genotoxicity and mutagenicity. The present results, together with other previous
interesting observations that P558 promotes osseointegration, suggest that this new nickel-free stainless steel can represent a better alternative to other conventional steel alloys
Random Votes to Parties and Policies in Coalition Governments
Full text linkWe exploit a natural experiment involving a randomization of votes across parties within coalitions in all local elections in Italy for over a decade. A lottery on the position of party symbols in the ballot papers allows estimating the causal effect of increasing votes to parties for coalition policies. A non-marginal random boost of votes shifts budgetary spending towards the treated party's platform, but only for issues that are salient in that party's political manifesto. We study the chains of mechanisms mapping votes into policies and link it to an increase in bargaining power within legislative majorities. Parties leverage their higher electoral support to gain the appointment of politically affiliated cabinet members. Empowering different parties also leads to the selection of cabinets with different socio-demographic characteristics. The unintentional experiment helps shed new light on mechanisms mapping votes to parties into coalition policies
The timing of the demographic transition and economic growth
No full textThis research provides novel evidence that the time since the onset of the demographic transition affects growth dynamics across countries and within countries. This sheds light on a factor that has been neglected in the existing empirical growth literature
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Medication against conflict
Full text linkAdverse health conditions and social conflict constitute major impediments for developing countries. The potential for reducing social conflict by successful public health interventions is largely unknown. This paper closes this gap by evaluating the effect of a major health intervention-the successful expansion of antiretroviral therapy (ART) to combat the HIV/AIDS pandemic in Africa. Combining exogenous time variation in access to ART with cross-sectional variation in the scope for treatment for identification, we find that the ART expansion significantly reduced the number of violent events in African countries and sub -national regions. The effect pertains to social conflict, not civil war. The evidence also shows that the effect is related to health improvements, greater approval of government policy, and increased trust in political institutions. Results of a counterfactual simulation reveal that the ART expansion reduced the number of social conflict events by about 10%
Promising in vitro performances of a new nickel-free stainless steel
No full textStainless steel is a metallic alloy largely employed in orthopaedics. However, the presence in its composition of a high quantity of nickel, an agent known to trigger toxic and allergic responses, is cause for concern. In this study, we have investigated the in vitro biocompatibility of a new nickel-reduced stainless steel, namely Bohler P558, in comparison to the conventional stainless steel AISI 316L. The neutral red (NR) uptake and the amido black (AB) tests were performed on L929 fibroblasts and MG63 osteoblasts to assess the cytotoxicity, while cytogenetic effects were evaluated on CHOK1 cells by studying the frequency of Sister Chromatid Exchanges (SCE) and chromosomal aberrations. Ames test was used to detect the mutagenic activity. The expression of selected markers typical of differentiated osteoblasts, such as alkaline phosphatase activity (ALP), type I collagen (CICP) and osteocalcin (OC) production, were also monitored in MG63 cells cultured on the tested materials. Our results indicate the absence of significant cytotoxicity and genotoxicity for both test alloys. ALP, CICP and OC analyses confirmed that both materials support the expression of these phenotypic markers. Overall, these data show that this Ni-free alloy possesses good in vitro biocompatibility and could have a potential for orthopaedic applications
Historical social contracts and their legacy: a disaggregated analysis of the medieval republics
Full text linkWe study the comparative political economy within the territories ruled by the medieval republics in Northern Italy. Building on the historical evidence, we conceptualize the emergence of more inclusive vs. extractive institutions in these sovereign polities as driven by the interests of local rulers and their need to build state capacity. We provide novel insights on the role of geography and historical contingencies in the development of public governance, individual attitudes, and social-inclusion, which mutually supported each other and persisted over time. We measure the origin, territorial evolution, and disappearance of all the sovereign polities that ruled over the Italian peninsula during the period of 1000-1800 AD. The empirical analysis connects contemporary socio-economic outcomes across spatially disaggregated northern Italian localities, at the municipality level, to local political history. We distinguish between so-called “communal” and “maritime republics” and show that the intensity and stability of exposure to the different types of republican rule in pre-industrial times continues to shape local public good provision and individual fiscal compliance, and has left a tangible imprint on today’s population diversity
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
