1,721,763 research outputs found
Ferromagnetism and Conductivity in Hydrogen Irradiated Co-Doped ZnO Thin Films
No full textImpressive changes in the transport and ferromagnetic properties of Co-doped ZnO thin films have been obtained by postgrowth hydrogen irradiation at temperatures of 400 °C. Hydrogen incorporation increases the saturation magnetization by one order of magnitude (up to ∼1.50 μB/Co) and increases the carrier density and mobility by about a factor of two. In addition to the magnetic characterization, the transport and structural properties of hydrogenated ZnO:Co have been investigated by Hall effect, local probe conductivity measurements, micro-Raman, and X-ray absorption spectroscopy. Particular care has been given to the detection of Co oxides and metal Co nanophases, whose influence on the increase in the transport and ferromagnetic properties can be excluded on the ground of the achieved results. The enhancement in ferromagnetism is directly related to the dose of H introduced in the samples. On the contrary, despite the shallow donor character of H atoms, the increase in carrier density n is not related to the H dose. These apparently contradictory effects of H are fully accounted for by a mechanism based on a theoretical model involving Co-VO (Co-O vacancy) pairs. © 2016 American Chemical Society
The effect of Co doping on the conductive properties of ferromagnetic ZnxCo1-xO films
No full textThe investigation of the electrical properties of Co-doped ZnO thin films provides two unexpected results: a decrease of the electrical conductivity and the contemporary occurrence of a reduction of conductivity and of an enhancement of ferromagnetic order. The former result is surprising since Zn atoms are replaced with iso-valent Co atoms. The latter finding questions previously suggested beneficial effects of n-type doping on the ZnO:Co magnetic behavior. While morphological and structural characterization permits us to exclude an influence of the morphology and of the presence of Co metal or Co-oxide phases on present experimental findings, with the aid of first-principles electronic structure calculations, we propose a qualitative picture which can explain in a coherent way both the changes in conductivity and ferromagnetic behavior ensuing from the Co doping and the above-mentioned, beneficial effects of n-type doping. This journal is © The Royal Society of Chemistry
ARCS: The Asiago Red Clump Spectroscopic Survey and its First Applications
Full text linkThe PhD thesis "ARCS" the Asiago Red Clump Survey and its first applications" is based on the study and the use of Red Clump stars, utilizing the data from ARCS and RAVE surveys.
The high luminosity, constant absolute magnitude and abundance, make Red Clump stars a powerful distance indicator and, consequently, they are an important tool for ever astrophysical question in which distance problem is relevant.
ARCSs (the Asiago Red Clump Spectroscopic survey) derives from high resolution optical spectra, accurate multi-epoch radial velocities and atmospheric parameters for a well selected sample of 500 equatorial Red Clump stars (|b|<6°) , belonging to the solar neighborhood. Spectra are obtained with the Asiago 1.82m + Echelle spectrograph, they cover a wide spectral interval (3700-7300 Å) with a high resolution (R = 20,000) . Radial velocity measurements are performed by cross-correlating spectra against synthetic templates; atmospheric parameters are derived via χ2 fitting with a synthetic database of spectra. The synthetic spectra are taken from the library of Munari et al. (2005, A&A 442,1127), based on Kurucz's codes.
The PhD research succeded in:
-the creation of a wide catalog of RC stars;
-to better investigate the structure of this type of stars;
-to calibrate dependence of the absolute magnitude of RC stars against the metallicity;
-to apply this function in order to define the use of RC stars as standard candles;
-the use of this type of stars for analyzing Milky Way structure and kinematics.La tesi di dottorato da titolo "ARCS: The Asiago Red Clump Survey and its firs applications" si occupa di meglio indagare e caratterizzare le
stelle di Red Clump locali, al fine di utilizzare questo tipo di stelle come
indicatori di distanza, struttura e cinematica della Via Lattea .
Il progetto comprende la survey ARCS (Asiago Red Clump
spectroscopic Survey) e si e' occupato di
sfruttarne scientificamente i risultati. Parte del progetto e'stato effettuato in collaborazione con
K. Freeman del Mt Stromlo Observatory.
Il risultato di
questo lavoro e' un esteso catalogo
di parametri atmosferici e velocita' radiali per un campione di 300 stelle di Red Clump.
I dati ottenuti sono stai applicati a problemi classici di struttura e cinematica galattica, come la
detection di streams, la determinazione della velocità di fuga locale e
presenza di dark matter
Historical and doctrinal roots of scandinavian national-populism
Full text linkThere has been an increase in the number of populist parties and movements, especially in Europe, yet their electoral successes have been sporadic. In Scandinavian countries the presence of such parties and movements has become a steady and, it seems, permanent feature of the political landscape. Their once shocking rhetoric and policies have become part of the political mainstream. The ability of populist political parties in Scandinavia to gain electoral success, hence to stabilise, may suggests that populism in Scandinavia may either result from a peculiar type of diversification within the very broadly conceived populist political stream, or may be one of unexpected outcomes of the so-called Scandinavian model of politics to be regarded then as a rather fertile ground for populists. The contribution that this study aims to offer is two-fold: placing Scandinavian populism in a wider context, thereby addressing the issue of the uniqueness of Scandinavian political culture; problematizing the rather common assumption that the variance among populist phenomena has increased exponentially over time. Indeed, the following specific key-questions have been asked and answered: are there distinctive facts that set today’s populist movements in Scandinavia apart from populist and nationalist ideas and programmes of the past? What are the ties relating the different populist movements in Scandinavia to each other? Are there any compelling indicators that may convince us that Scandinavian populism is somewhat different from its counterparts elsewhere? Finally, based on a number of findings, we shall evaluate the claim that a distinct, Scandinavian form of populism exists. The first part of the text deals with the complex question choosing a working definition of populism. It then moves on to describing the historical understandings of ‘populism’ and ‘nationalism’, as well as identifying some of the main distinguishing features of populist and nationalist movements in the past, for then to describe, through case studies, some of the many features we may find in different, contemporary, populist party ‘families’. We sustain the that a typology defined by two overarching families of populism - whether it allows for further sub-families or not - fails to capture the full range of phenomena referred to as populist politics in Scandinavia. By first identifying some of the historical cases in which evident traces of populism are detectable, we shall see that the split nature of populism itself is not a result of a process of diversification, but rather a case of different phenomena that, from the very outset, happened to share a few common features. We propose an interpretation by which, rather than fascism being a form of populism, or combining populism with another ideology, the two belong to a similar type of ideology: they can both be understood as belonging among the so-called ‘thin-centred ideologies’. Here we do not mean that a similarity in content is necessarily significant, but rather that they both, when combined with ideological content from the more traditional left – or right-wing, or with a combination of policies from both ends of the spectrum, become political programmes with high potential and appeal, especially during times of (perceived) crisis. Thus, what we have been able to observe is that the theory that nationalism arises in times of crises where, typically the lower middle classes, or the lower classes, feel the pressure of economic decline in combination with factors such as immigration, seems to hold the first test against historical cases. We further conclude that populist radical right parties in Europe share a core ideology of nativism, authoritarianism, and populism. In the contemporary context, we conclude that a definition of populism in terms of one or more fixed, necessary and exclusive common feature(s) is unfeasible, and we must then continue with a definition of populism which is in line with Sartori’s minimal definition, in combination with the presumption that a plethora of sub-categories may exist. The common denominators are thus: the reference to the ‘people’ as harbouring the real essence of a particular society, to the ‘populists’ as having discovered the best way of letting the spirit of the people speak, and to the perceived conflict of interest between the people on the one hand and a particular, or general, elite on the other. The investigation of the parallels between the historical definitions of ‘populism’ and ‘nationalism’ helps us understand the ideological roots of each of the populist parties and movements in Scandinavia. For example, the abandonment of the use of the rational and legal concept of ‘citizenship’ in favour of the use of the vague concept of ‘Volk’ among the German romantics is one of the features that emphasize how the Scandinavian parties have adopted many of the ideas of this particular movement; especially in terms of defining the concepts of ‘nation’ and ‘national-culture’, or ‘-character’. The second part of the text includes a general introduction to some interesting social and political features of each of the national contexts within which our subjects of study belong. We propose the term ‘national-populist’ to denominate the general typology of most Scandinavian populist parties and movements. We also show how many of these parties have direct links with both national-socialist parties of the past and with each other, and how the promotion of Scandinavian regionalism has created a sense of shared experience and ontology. We also show, however, how local circumstances and historical features have shaped some of these parties. We then move on to treat the societal features that are most frequently used by journalists and scholars, not to mention by Scandinavian populist leaders themselves, to explain the founding of the populist parties and movements in Scandinavian countries on the one hand, and their relative popularity on the other. It becomes clear that many of the features of the populist parties in Scandinavian countries are shared (such as ideas about what constitutes a ‘folk’ and a nation, a shared Scandinavian regionalism and a common perception of economic and social crisis), the emphasis on each of these features differs from party to party. It also become clear, however, that the features that are shared among these parties, cannot claim exclusivity. Scandinavian national-populist parties and movements do thus not constitute a separate sub-category of populism, but rather constitute examples of the slightly wider sub-category of ‘national-populism’
Psychomotor education to foster mathematical logic skills - L'educazione motoria nell'apprendimento delle abilità logico-matematiche
No full textL’attacco di sali solubili su murature in laterizio. Analisi sperimentale di quattro prodotti antisale
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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
Effect of carbon nanofibres dispersion on the microwave absorbing properties of CNF/epoxy composites
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