1,641 research outputs found
Análise comparativa de modelos para estimativa de índices obtidos a partir de imagens de satélite.
The lecture video recording in university: A case study
The latest European statistics show that Italy has the second lowest percentage of university graduates because of different reasons such as the outdated teaching methodologies or the high costs of university tuitions. Hence, Italian universities have launched several projects to improve or innovate the pedagogical strategies, to raise the student recruitment and to increase access to education. In this work, we describe a pilot study about the use of the video recording of the traditional lessons in order to create specific university MOOCs. In particular, the degree course in Computer Science of University of Naples Federico II is involved in this project. The use of the lecture video recording reduces the MOOC costs and facilitates the contents management. In fact, the production of these MOOCs does not require professional operators so it is possible to involve students of university part-time job or Civil Service volunteers. The results show a good satisfaction by students and prove as these MOOCs can support the university teaching
Phytochemical investigations on Artemisia alba Turra growing in the North-East of Italy
Artemisia alba Turra (Asteraceae) is an Euro-Mediterranean plant used in Veneto (North-East of Italy) as traditional medicine for the treatment of various diseases. A. alba is a taxonomically problematic species, characterized by common polymorphism leading to a quite high variability in secondary metabolites content. Nonetheless, the phytochemical knowledge on its phytoconstituents, especially non-volatile components, is limited. In the present paper, the phytochemical composition of a tincture obtained from the aerial parts of A. alba growing in Veneto is presented. Extensive chromatographic separations led to the isolation of three new sesquiterpene derivatives, whose structures were elucidated by 1D and 2D NMR experiments and mass spectrometry. Furthermore, flavonoid composition and volatile constituents of the tincture of A. alba were preliminary studied by HPLC-MSn and GC-MS, respectivel
The Comparative Exploration of the Ice Giant Planets with Twin Spacecraft: Unveiling the History of our Solar System
In the course of the selection of the scientific themes for the second and
third L-class missions of the Cosmic Vision 2015-2025 program of the European
Space Agency, the exploration of the ice giant planets Uranus and Neptune was
defined "a timely milestone, fully appropriate for an L class mission". Among
the proposed scientific themes, we presented the scientific case of exploring
both planets and their satellites in the framework of a single L-class mission
and proposed a mission scenario that could allow to achieve this result. In
this work we present an updated and more complete discussion of the scientific
rationale and of the mission concept for a comparative exploration of the ice
giant planets Uranus and Neptune and of their satellite systems with twin
spacecraft. The first goal of comparatively studying these two similar yet
extremely different systems is to shed new light on the ancient past of the
Solar System and on the processes that shaped its formation and evolution.
This, in turn, would reveal whether the Solar System and the very diverse
extrasolar systems discovered so far all share a common origin or if different
environments and mechanisms were responsible for their formation. A space
mission to the ice giants would also open up the possibility to use Uranus and
Neptune as templates in the study of one of the most abundant type of
extrasolar planets in the galaxy. Finally, such a mission would allow a
detailed study of the interplanetary and gravitational environments at a range
of distances from the Sun poorly covered by direct exploration, improving the
constraints on the fundamental theories of gravitation and on the behaviour of
the solar wind and the interplanetary magnetic field.Comment: 29 pages, 4 figures; accepted for publication on the special issue
"The outer Solar System X" of the journal Planetary and Space Science. This
article presents an updated and expanded discussion of the white paper "The
ODINUS Mission Concept" (arXiv:1402.2472) submitted in response to the ESA
call for ideas for the scientific themes of the future L2 and L3 space
mission
Statistical pairwise interaction model of stock market
Financial markets are a classical example of complex systems as they comprise
many interacting stocks. As such, we can obtain a surprisingly good description
of their structure by making the rough simplification of binary daily returns.
Spin glass models have been applied and gave some valuable results but at the
price of restrictive assumptions on the market dynamics or others are
agent-based models with rules designed in order to recover some empirical
behaviours. Here we show that the pairwise model is actually a statistically
consistent model with observed first and second moments of the stocks
orientation without making such restrictive assumptions. This is done with an
approach based only on empirical data of price returns. Our data analysis of
six major indices suggests that the actual interaction structure may be thought
as an Ising model on a complex network with interaction strengths scaling as
the inverse of the system size. This has potentially important implications
since many properties of such a model are already known and some techniques of
the spin glass theory can be straightforwardly applied. Typical behaviours, as
multiple equilibria or metastable states, different characteristic time scales,
spatial patterns, order-disorder, could find an explanation in this picture.Comment: 11 pages, 8 figure
Cognitive Influences on Flavor Discrimination: Training Novices For Beer Flavor Differentiation
Four training techniques were employed to investigate the effects of increasing knowledge of beer flavor on novices\u27 ability to differentiate among beers on the basis of taste. These techniques included (a) learning definitions of beer flavor terminology (Verbal Condition); (b) having additional experience with taste sensations (Taste Condition); (c) having a combination of the verbal and taste techniques (Verbal/Taste Condition); and (d) no training (Control Condition). After preliminary testing, 40 subjects (10 per training condition) were selected to participate in pre- and post-training tasks in which they rated similarity between beers, between beers and flavor-descriptive adjectives, and between flavor-descriptive adjectives.
Each Subject\u27s performance was compared to that of an expert brewmeister by means of multidimensional scaling analyses. Results indicated that although all participants unexpectedly revealed an overall decrease in congruence to the expert after training (including the Control condition), subjects in the Taste Condition showed significant effects of training in their ability to match identical beer flavors. The observed decrease in overall congruence was apparently the result of subjects\u27 inability to assimilate new semantic information along with new perceptual experiences into a coherent cognitive structure. Training that included verbal information led to greater confusion in relating terms to flavors than was the case before training. Further research should focus on increased training of novices as well as training of discriminators
Measurement of the quality factor of a new low-frequency differential accelerometer for testing the equivalence principle
A cryogenic differential accelerometer has been developed to test the weak equivalence principle to a few parts in 1015 within the framework of the general relativity accuracy test in an Einstein elevator experiment. The prototype sensor was designed to identify, address, and solve the major issues associated with various aspects of the experiment. This paper illustrates the measurements conducted on this prototype sensor to attain a high quality factor (Q ∼ 105) at low frequencies (<20 Hz). Such a value is necessary for reducing the Brownian noise to match the target acceleration noise of 10−14 g/√Hz, hence providing the desired experimental accuracy.AstronomyPhysic
Spectral Theory of Sparse Non-Hermitian Random Matrices
Sparse non-Hermitian random matrices arise in the study of disordered
physical systems with asymmetric local interactions, and have applications
ranging from neural networks to ecosystem dynamics. The spectral
characteristics of these matrices provide crucial information on system
stability and susceptibility, however, their study is greatly complicated by
the twin challenges of a lack of symmetry and a sparse interaction structure.
In this review we provide a concise and systematic introduction to the main
tools and results in this field. We show how the spectra of sparse
non-Hermitian matrices can be computed via an analogy with infinite dimensional
operators obeying certain recursion relations. With reference to three
illustrative examples -- adjacency matrices of regular oriented graphs,
adjacency matrices of oriented Erd\H{o}s-R\'{e}nyi graphs, and adjacency
matrices of weighted oriented Erd\H{o}s-R\'{e}nyi graphs -- we demonstrate the
use of these methods to obtain both analytic and numerical results for the
spectrum, the spectral distribution, the location of outlier eigenvalues, and
the statistical properties of eigenvectors.Comment: 60 pages, 10 figure
- …
