8,395 research outputs found
On characters of Chevalley groups vanishing at the non-semisimple elements
Let G be a finite simple group of Lie type. In this paper we study characters
of G that vanish at the non-semisimple elements and whose degree is equal to
the order of a maximal unipotent subgroup of G. Such characters can be viewed
as a natural generalization of the Steinberg character. For groups G of small
rank we also determine the characters of this degree vanishing only at the
non-identity unipotent elements.Comment: Dedicated to Lino Di Martino on the occasion of his 65th birthda
CCD and photon-counting photometric observations of asteroids carried out at Padova and Catania observatories
We present the results of observational campaigns of asteroids performed at
Asiago Station of Padova Astronomical Observatory and at M.G. Fracastoro
Station of Catania Astrophysical Observatory, as part of the large research
programme on Solar System minor bodies undertaken since 1979 at the Physics and
Astronomy Department of Catania University. Photometric observations of six
Main-Belt asteroids (27 Euterpe, 173 Ino, 182 Elsa, 539 Pamina, 849 Ara, and
984 Gretia), one Hungaria (1727 Mette), and two Near-Earth Objects (3199
Nefertiti and 2004 UE) are reported. The first determination of the synodic
rotational period of 2004 UE was obtained. For 182 Elsa and 1727 Mette the
derived synodic period of 80.23+/-0.08 h and 2.981+/-0.001 h, respectively,
represents a significant improvement on the previously published values. For
182 Elsa the first determination of the H-G magnitude relation is also
presented.Comment: 19 pages, 11 figures, accepted for publication in Planetary and Space
Scienc
Prospective teachers' interpretative knowledge: giving sense to subtraction algorithms
The process of interpretation and assessment of students’ mathematical productions represents a crucial aspect of teachers’ practices. In such processes, teachers rely on the so-called interpretative knowledge, which includes particular aspects of their mathematical and pedagogical knowledge, their view of mathematics, and their values. In this paper, we analyze and discuss prospective primary teachers’ interpretative knowledge gained through their assessment of different subtraction algorithms
Feynman graphs and the large dimensional limit of multipartite entanglement
We are interested in the properties of multipartite entanglement of a system
composed by -level parties (qudits).
Focussing our attention on pure states we want to tackle the problem of the
maximization of the entanglement for such systems. In particular we effort the
problem trying to minimize the purity of the system. It has been shown that not
for all systems this function can reach its lower bound, however it can be
proved that for all values of a can always be found such that the lower
bound can be reached.
In this paper we examine the high-temperature expansion of the distribution
function of the bipartite purity over all balanced bipartition considering its
optimization problem as a problem of statistical mechanics. In particular we
prove that the series characterizing the expansion converges and we analyze the
behavior of each term of the series as .Comment: 29 pages, 11 figure
Spectral Graph Convolutions for Population-based Disease Prediction
Exploiting the wealth of imaging and non-imaging information for disease
prediction tasks requires models capable of representing, at the same time,
individual features as well as data associations between subjects from
potentially large populations. Graphs provide a natural framework for such
tasks, yet previous graph-based approaches focus on pairwise similarities
without modelling the subjects' individual characteristics and features. On the
other hand, relying solely on subject-specific imaging feature vectors fails to
model the interaction and similarity between subjects, which can reduce
performance. In this paper, we introduce the novel concept of Graph
Convolutional Networks (GCN) for brain analysis in populations, combining
imaging and non-imaging data. We represent populations as a sparse graph where
its vertices are associated with image-based feature vectors and the edges
encode phenotypic information. This structure was used to train a GCN model on
partially labelled graphs, aiming to infer the classes of unlabelled nodes from
the node features and pairwise associations between subjects. We demonstrate
the potential of the method on the challenging ADNI and ABIDE databases, as a
proof of concept of the benefit from integrating contextual information in
classification tasks. This has a clear impact on the quality of the
predictions, leading to 69.5% accuracy for ABIDE (outperforming the current
state of the art of 66.8%) and 77% for ADNI for prediction of MCI conversion,
significantly outperforming standard linear classifiers where only individual
features are considered.Comment: International Conference on Medical Image Computing and
Computer-Assisted Interventions (MICCAI) 201
Towards Optimal Energy-Water Supply System Operation for Agricultural and Metropolitan Ecosystems
The energy-water demands of metropolitan regions and agricultural ecosystems
are ever-increasing. To tackle this challenge efficiently and sustainably, the
interdependence of these interconnected resources has to be considered. In this
work, we present a holistic decision-making framework which takes into account
simultaneously a water and energy supply system with the capability of
satisfying metropolitan and agricultural resource demands. The framework
features: (i) a generic large-scale planning and scheduling optimization model
to minimize the annualized cost of the design and operation of the energy-water
supply system, (ii) a mixed-integer linear optimization formulation, which
relies on the development of surrogate models based on feedforward artificial
neural networks and first-order Taylor expansions, and (iii) constraints for
land and water utilization enabling multi-objective optimization. The framework
provides the operational profiles of all energy-water system elements over a
given time horizon, which uncover potential synergies between the essential
food, energy, and water resource supply systems.Comment: Part of the Foundations of Computer-Aided Process Operations and
Chemical Process Control (FOCAPO/CPC) 2023 Proceeding
Continuous monitoring of hydrogen and carbon dioxide at Mt Etna
This study assessed the use of an H2 fuel cell as an H2-selective sensor for volcano monitoring. The resolution,
repeatability, and cross-sensitivity of the sensor were investigated and evaluated under known laboratory
conditions. A tailor-made device was developed and used for continuously monitoring H2 and CO2 at Mt Etna
throughout 2009 and 2010. The temporal variations of both parameters were strongly correlated with the
evolution of the volcanic activity during the monitoring period. In particular, the CO2 flux exhibited long-term
variations, while H2 exhibited pulses immediately before the explosive activity that occurred at Mt Etna during
2010
The Logical Intelligence Enhancement Program (LIEP) for the improvement of cognitive abilities. Premilinary findings
The Logical Intelligence Enhancement Program (LIEP) is a program specifically addressed to students aging from 6 to 12. It consists of a series of exercises of different types (verbal inferences, understanding of graphs and tables, series of digits, etc.) and increasing difficulty, properly devised to activate and train the abilities of logical reasoning. Hopefully, such an enhancement should result in an improvement of academic achievements, especially in low proficiency learner students. Here we report on a study carried out on a large cohort of fifth-grade students. The results demonstrate the effectiveness of LIEP in improving students’ cognitive abilities and abstract reasoning
The autism brain imaging data exchange: towards a large-scale evaluation of the intrinsic brain architecture in autism
Autism spectrum disorders (ASDs) represent a formidable challenge for psychiatry and neuroscience because of their high prevalence, lifelong nature, complexity and substantial heterogeneity. Facing these obstacles requires large-scale multidisciplinary efforts. Although the field of genetics has pioneered data sharing for these reasons, neuroimaging had not kept pace. In response, we introduce the Autism Brain Imaging Data Exchange (ABIDE)—a grassroots consortium aggregating and openly sharing 1112 existing resting-state functional magnetic resonance imaging (R-fMRI) data sets with corresponding structural MRI and phenotypic information from 539 individuals with ASDs and 573 age-matched typical controls (TCs; 7–64 years) (http://fcon_1000.projects.nitrc.org/indi/abide/). Here, we present this resource and demonstrate its suitability for advancing knowledge of ASD neurobiology based on analyses of 360 male subjects with ASDs and 403 male age-matched TCs. We focused on whole-brain intrinsic functional connectivity and also survey a range of voxel-wise measures of intrinsic functional brain architecture. Whole-brain analyses reconciled seemingly disparate themes of both hypo- and hyperconnectivity in the ASD literature; both were detected, although hypoconnectivity dominated, particularly for corticocortical and interhemispheric functional connectivity. Exploratory analyses using an array of regional metrics of intrinsic brain function converged on common loci of dysfunction in ASDs (mid- and posterior insula and posterior cingulate cortex), and highlighted less commonly explored regions such as the thalamus. The survey of the ABIDE R-fMRI data sets provides unprecedented demonstrations of both replication and novel discovery. By pooling multiple international data sets, ABIDE is expected to accelerate the pace of discovery setting the stage for the next generation of ASD studies
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