The Incremental Multiresolution Matrix Factorization Algorithm

Multiresolution analysis and matrix factorization are foundational tools in computer vision. In this work, we study the interface between these two distinct topics and obtain techniques to uncover hierarchical block structure in symmetric matrices -- an important aspect in the success of many vision problems. Our new algorithm, the incremental multiresolution matrix factorization, uncovers such structure one feature at a time, and hence scales well to large matrices. We describe how this multiscale analysis goes much farther than what a direct global factorization of the data can identify. We evaluate the efficacy of the resulting factorizations for relative leveraging within regression tasks using medical imaging data. We also use the factorization on representations learned by popular deep networks, providing evidence of their ability to infer semantic relationships even when they are not explicitly trained to do so. We show that this algorithm can be used as an exploratory tool to improve the network architecture, and within numerous other settings in vision.Comment: Computer Vision and Pattern Recognition (CVPR) 2017, 10 page

YOUNG ITALIANS' MEDIA USE AND ATTITUDE TOWARDS IMMIGRATION

This paper describes a study aimed at analyzing whether and how certain technologies usage practices can lead to the construction of different perceptions in relation to social phenomena. In particular, the study enquires how the evolution in the way young people get informed, can lead to different attitudes towards a phenomenon such as immigration. The work aims to understand what kind of relationship exists between different media usage types and (over)exposure to the news – made possible by the web, particularly social media – and the perception (in cognitive and evaluative terms) of the presence of immigrants in Italy. To answer these questions, an empirical research was conducted using a qualitative and quantitative approach. In particular, the quantitative study was carried through a survey on a sample of 200 subjects and illustrates how the information system, new information technologies and media consumption strongly influence the way young Italian see the world, confirming a bias between their perception and what statistical data say about the environment in which they are living

Gaussian Approximation Potentials: the accuracy of quantum mechanics, without the electrons

We introduce a class of interatomic potential models that can be automatically generated from data consisting of the energies and forces experienced by atoms, derived from quantum mechanical calculations. The resulting model does not have a fixed functional form and hence is capable of modeling complex potential energy landscapes. It is systematically improvable with more data. We apply the method to bulk carbon, silicon and germanium and test it by calculating properties of the crystals at high temperatures. Using the interatomic potential to generate the long molecular dynamics trajectories required for such calculations saves orders of magnitude in computational cost.Comment: v3-4: added new material and reference

A component-level methodology to evaluate the seismic repair costs of infills and services for Italian RC buildings

The reliable estimation of seismic losses due to damage to buildings is paramount for the post-emergency management and the planning of recovery activities. For residential reinforced concrete (RC) infilled buildings, a significant role in the computation of seismic loss is played by non-structural components, above all infills, partitions and services, as shown in past earthquakes. In this work, a component-based methodology is proposed to assess seismic losses for residential RC buildings in Mediterranean region. The attention is focused on the repairing activities for masonry infills (typical enclosure or partitions elements in Italian and Mediterranean RC buildings), and for services (plumbing systems, electric equipment, floor/wall tiles…), commonly enclosed within the infill panels for the considered building typology. The described methodology can be used starting from the expected damage level to infills and partitions. It adopts given repair unit costs at different damage states of infills. The loss estimation methodology has been, first, validated by comparing predicted and actual repair costs for specific case-study buildings damaged by L’Aquila (Italy) 2009 earthquake. Then, the methodology has been applied to a wide dataset of RC buildings (about 2500 residential buildings) damaged by L’Aquila earthquake available from the literature, to show its possible application at a large-scale level. A good agreement between observed and predicted costs is obtained both for specific case-study buildings and for the wider building stock, especially when damage to structural components is very limited

Are Alkynyl Spacers in Ancillary Ligands in Heteroleptic Bis(diimine)copper(I) Dyes Beneficial for Dye Performance in Dye-Sensitized Solar Cells?

The syntheses of 4,40 -bis(4-dimethylaminophenyl)-6,60 -dimethyl-2,20 -bipyridine (1 ), 4,40 -bis(4-dimethylaminophenylethynyl)-6,60 -dimethyl-2,20 -bipyridine (2 ), 4,40 -bis(4- diphenylaminophenyl)-6,60 -dimethyl-2,20 -bipyridine (3 ), and 4,40 -bis(4-diphenylaminophenylethynyl)- 6,60 -dimethyl-2,20 -bipyridine (4 ) are reported along with the preparations and characterisations of their homoleptic copper(I) complexes [CuL2 ][PF6 ] (L = 1 -4 ). The solution absorption spectra of the complexes exhibit ligand-centred absorptions in addition to absorptions in the visible region assigned to a combination of intra-ligand and metal-to-ligand charge-transfer. Heteroleptic [Cu(5 )(Lancillary )]+ dyes in which 5 is the anchoring ligand ((6,60 -dimethyl-[2,20 -bipyridine]- 4,40 -diyl)bis(4,1-phenylene))bis(phosphonic acid) and Lancillary = 1 -4 have been assembled on fluorine-doped tin oxide (FTO)-TiO2 electrodes in dye-sensitized solar cells (DSCs). Performance parameters and external quantum e ciency (EQE) spectra of the DSCs (four fully-masked cells for each dye) reveal that the best performing dyes are [Cu(5 )(1 )]+ and [Cu(5 )(3 )]+ . The alkynyl spacers are not beneficial, leading to a decrease in the short-circuit current density (JSC ), confirmed by lower values of EQEmax . Addition of a co-absorbent (n -decylphosphonic acid) to [Cu(5 )(1 )]+ lead to no significant enhancement of performance for DSCs sensitized with [Cu(5 )(1 )]+ . Electrochemical impedance spectroscopy (EIS) has been used to investigate the interfaces in DSCs; the analysis shows that more favourable electron injection into TiO2 is observed for sensitizers without the alkynyl spacer and confirms higher JSC values for [Cu(5 )(1 )]

Geostatistics to evaluate the automatic acquisiton of sound pressure levels in pig nursery facilities

Este trabalho teve o objetivo de estudar a influência da distribuição de decibelímetros na captação automática dos níveis de pressão sonora, em ambiente de produção intensiva de suínos. O experimento foi conduzido em sala do setor de creche de uma granja comercial de suínos situada no município de Monte Mor, Estado de São Paulo. A sala foi dividida em dez quadrantes idênticos, e os decibelímetros foram instalados no centro geométrico de cada quadrante. Utilizou-se a geoestatística para avaliar a dependência espacial entre os decibelímetros e para predizer os níveis de pressão sonora em locais onde estes não foram instalados. Os dados foram analisados pela correlação entre os decibelímetros e por intermédio da geoestatística, que possibilitou afirmar que não houve dependência espacial entre os pontos de registro dos níveis de pressão sonora. Por intermédio da interpolação dos pontos de captura utilizando o processo de krigagem, foi possível predizer os níveis de pressão sonora nos locais onde não havia decibelímetros no interior da instalação. Verificou-se homogeneidade de propagação dos níveis de pressão sonora no interior da instalação, concluindo que, para o ambiente avaliado, o uso de somente um equipamento para o registro automático dos níveis de pressão sonora é suficiente.The objective of this work was to study the influence of decibelimeters distribution in the automatic acquisition of sound pressure levels in pig nursery facilities. The experiment was conducted in a nursering room of a commercial swine's facility situated in the city of Monte Mor, State of São Paulo, Brazil. The room was divided in ten identical quadrants and the geometrical center of each quadrant was installed the decibelimeters. Geostatistics was used to evaluate the spatial dependence among the decibelimeters and to predict sound pressure levels in the places that they were not installed. Data were analyzed by the correlation among decibelimeters and through geostatistics, being possible to affirm that there was no spatial dependence between recording points of the sound pressure levels. Through interpolation of registration points using kriging process, was possible to predict sound pressure levels in places with no decibelimeters inside the facility. It was verified homogeneity in the sound pressure levels propagation inside the facility, concluding that to the evaluated environment, the use of only one equipment to the automatic registration of sound pressure levels is enough

Back to the future: asymmetrical DπA 2,2'-bipyridine ligands for homoleptic copper(I)-based dyes in dye-sensitized solar cells

Metal complexes used as sensitizers in dye-sensitized solar cells (DSCs) are conventionally constructed using a push-pull strategy with electron-releasing and electron-withdrawing (anchoring) ligands. In a new paradigm we have designed new D π A ligands incorporating diarylaminophenyl donor substituents and phosphonic acid anchoring groups. These new ligands function as organic dyes. For two separate classes of D π A ligands with 2,2'-bipyridine metal-binding domains, the DSCs containing the copper(I) complexes [Cu(D π A) 2 ] + perform better than the push-pull analogues [Cu(D D )(AA) ] + . Furthermore, we have shown for the first time that the complexes [Cu(D π A) 2 ] + perform better than the organic D π A dye in DSCs. The synthetic studies and the device performances are rationalised with the aid of density functional theory (DFT) and time-dependent DFT (TD-DFT) studies

Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies

The lessons learned after recent earthquakes have highlighted the key role played by infills and services in damage and loss of Reinforced Concrete (RC) buildings. Their influence in seismic performance and loss estimation of selected RC building case studies is thoroughly analyzed here. The case study selection aims to be representative of existing buildings built in Italy before 1970, and covers a different number of stories and design typologies. The seismic responses of the case-study buildings are numerically analyzed by means of non-linear static pushover analysis (PO) considering a lumped plasticity approach with a quadri-linear flexural response for beam/column elements (properly calibrated for RC elements reinforced with plain bars) and a tri-linear compressive-only axial response with diagonal concentric struts for infill panels (empirically derived from experimental data on hollow clay masonry walls). Economic loss estimation is carried out via a component-based methodology that relies on the main repairing activities and resultant costs required for the refurbishment of infills and services for different damage levels. Accordingly, a damage analysis is performed herein, given the intensity measure, based on a comparison between Interstory drift demand from PO analysis and drift-based fragility functions specific for masonry infills. Loss curves, relating the total building repair cost to peak ground acceleration (PGA), are presented and compared for the analyzed case study buildings to show their trends and quantify the incidence of infills and services with respect to the reconstruction cost. A comparison between these outcomes and those recently found in the literature emphasizes the robustness of the considered approach and the reliability of the hypotheses about damage and loss assessment

Quantifying molecular oxygen isotope variations during a Heinrich stadial

International audienceδ 18 O of atmospheric oxygen (δ 18 O atm) undergoes millennial-scale variations during the last glacial period, and systematically increases during Heinrich stadials (HSs). Changes in δ 18 O atm combine variations in biospheric and water cycle processes. The identification of the main driver of the millennial variability in δ 18 O atm is thus not straightforward. Here, we quantify the response of δ 18 O atm to such millennial events using a freshwater hosing simulation performed under glacial boundary conditions. Our global approach takes into account the latest estimates of isotope frac-tionation factor for respiratory and photosynthetic processes and make use of atmospheric water isotope and vegetation changes. Our modeling approach allows to reproduce the main observed features of a HS in terms of climatic conditions , vegetation distribution and δ 18 O of precipitation. We use it to decipher the relative importance of the different processes behind the observed changes in δ 18 O atm. The results highlight the dominant role of hydrology on δ 18 O atm and confirm that δ 18 O atm can be seen as a global integrator of hydrological changes over vegetated areas