1,721,041 research outputs found
Melting of cooperative Jahn-Teller distortion in KMg0.2Cu0.8F3
No full textKCuF3 is a Mott-Hubbard insulator with a distorted perovskite structure (space group I4/mcm). The structural distortion is due to orbital ordering (OO) associated with cooperative Jahn-Teller effect (JT) [1]. and corresponds to an alternate occupation of Cu-3dy2-z2 and Cu-3dx2-z2 hole states on Cu(3d9) ion [2]. The orbital configuration results in quasi one-dimensional magnetic properties. Nearest-neighbour superexchange (NN-SE) interactions are strong and antiferromagnetic (AF) along the c axis and, for T>TN=38 K, weak and ferromagnetic in the ab plane. Debate is open in the literature on the actual driving force (i.e. either OO or JT) of the structural distortion and of the related electronic and magnetic properties. We have recently found experimental evidence of the ideal situation in which OO is melted while the JT distortion is still present:, in fact OO is expected to be very sensitive to slight changes in the electronic structure. Electron paramagnetic resonance investigations revealed melting of OO at room temperature in the KCu1-xMgxF3 system for x=0.1 [3]. We presents here a Synchrotron Radiation X-ray powder diffraction (XRPD) study in a sample with composition KCu0.8Mg0.2F3, which at room temperature is isostructural with KCuF3, a prototypical system for studying Orbital Order (OO). This sample can be considered a realisation of the ideal situation in which OO is melted while the cooperative JT distortion is still present. The melting of the cooperative JT distortion is observed in this system for T~600 K. This result is discussed in the framework of the different energy scales for OO and cooperative JT distortion.
[1] L.F. Feiner, A.M. Oleś, J. Zaanen, Phys. Rev. Lett., 1997, 78, 2799. [2] R. Caciuffo, L. Paolasini, A. Sollier, P. Ghigna, E. Pavarini, J. van den Brink, M. Altarelli Phys.Rev., 2002, B65, 174425
[3] C. Oliva, M. Scavini, S. Cappelli, C. Bottalo, C. Mazzoli, P. Ghigna, J.Phys.Chem., 2007, B111, 597
Risk profiling and current suitability practices: what can be learned from a sample of Italian householders
No full textAccording to the Markets in Financial Instruments Directive (MiFID), financial intermediaries are requested to assess the suitability of the products they sell to clients, particularly in respect of retail clients. Supervisory Authorities have pointed out that one of the main problems in the practical implementation of the MiFID suitability rule stems from the omission or impreciseness of the questions addressed to know the customer’s characteristics with specific reference to their risk profile. With this paper we try to shed light on the information an intermediary should collect from customers in order to properly define their risk profile. We analyze a sample of 2995 suitable portfolios and we put their risk composition in relation with some characteristics of the owner. By using the Heckit two-steps estimation procedure we are also able to set apart the variables that mainly explain the risk-holding decision (whether to acquire risky assets) and the risk-allocation decision (what fraction of wealth to invest in these assets). We find that the former decision may be induced by a smaller set of variables,
essentially related to the capability of understanding and emotionally bearing the risk, while the latter is more related to the individual economic and financial capacity
The role of risk in the investment decision process: traditional vs behavioural finance (Chapter 1)
No full textLa costruzione industrializzata in Italia. Progetti e Prototipi (1945-1980)
No full textLa ricerca ( condotta nell’ambito del progetto PRIN, “La costruzione industrializzata in Italia t ra gli anni '60 e gli anni '80”, coordinatore Sergio Poretti) fornisce una ricostruzione storica del tentativo di industrializzare il settore della costruzione nel secondo dopoguerra in Italia. Attraverso l’indagine sulle opere e sui progetti, lo studio mette in luce le specificità dell’esperienza italiana nella distanza dai processi d’industrializzazione condotti in Europa
Edifici industriali dismessi: metodologie e tecnologie per un recupero sostenibile.
No full textIl tema della rigenerazione di edifici ed aree industriali dismesse è di grande attualità per le notevoli implicazioni sia sul piano socio-economico che urbanistico e ambientale. Nel contributo proposto viene presentato un modello di riuso in cui sono considerati sia gli aspetti che intervengono alla scala urbana che a quella edilizia. Il modello è articolato nelle seguenti fasi: analisi delle potenzialità di riconversione del manufatto industriale, valutazione del grado di compatibilità con le diverse normative tecniche (sicurezza strutturale, sicurezza antincendio, eliminazione barriere architettoniche, efficienza energetica), definizione dei criteri di intervento
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
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
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