Exploiting Linked Open Data and Natural Language Processing for Classification of Political Speech

This paper shows the effectiveness of a DBpedia-based approach for text categorization in the e-government field. Our use case is the analysis of all the speech transcripts of current White House members. This task is performed by means of TellMeFirst, an open-source software that leverages the DBpedia knowledge base and the English Wikipedia linguistic corpus for topic extraction. Analysis results allow to identify the main political trends addressed by the White House, increasing the citizens' awareness to issues discussed by politicians. Unlike methods based on string recognition, TellMeFirst semantically classifies documents through DBpedia URIs, gathering all the words that belong to a similar area of meaning (such as synonyms, hypernyms and hyponyms of a lemma) under the same unambiguous concept

Un approccio basato su DBpedia per la sistematizzazione della conoscenza sul Web

La tesi propone una strategia per la sistematizzazione della conoscenza sul Web basata sui concetti presenti in DBpedia e finalizzata alla riduzione dell'information overload. L'opportunità dell'utilizzo di DBpedia è sostenuta sia da aspetti puramente tecnici sia da valutazioni più teoriche. Essendo DBpedia collegata a un vasto corpus multilingue preannotato di carattere enciclopedico (Wikipedia), essa risulta tecnicamente molto adatta ad essere utilizzata per procedimenti automatici di Natural Language Processing e di Text Mining. In aggiunta, i concetti presenti in DBpedia sono il risultato di un consenso semantico raggiunto in maniera collaborativa dalla comunità degli internauti. Un criterio efficace di classificazione sul Web non può essere imposto dall'alto, ma deve seguire gli stessi principi di libertà e trasparenza che hanno da sempre costituito l'essenza di Internet. Il primo capitolo della tesi descrive Wikipedia come un frutto di quell'intelligenza collettiva e di quella cultura collaborativa che sembrano emergere come i tratti costitutivi delle comunità in Rete. Vengono esaminate le posizioni di diversi autori sui concetti di intelligenza collettiva (come Pierre Lévy, James Surowiecki, David Weinberger, Micheal Nielsen) e di cultura collaborativa (tra cui Yochai Benkler, Manuel Castells, Henry Jenkins, Eric Raymond, Raffaele Meo). È proposta un'analisi dei punti di forza e di debolezza di Wikipedia per cercare di capire come tali aspetti possano influenzare la sua validità quale corpus annotato per la classificazione dei documenti online. Il secondo capitolo prende in esame DBpedia, inserendola nel contesto più ampio dei Linked Open Data. Si focalizza sui meccanismi tecnici che permettono la trasformazione della conoscenza semi-strutturata presente in Wikipedia nella conoscenza strutturata di DBpedia. DBpedia è vista come lo strumento più adatto per costruire un'ontologia della Rete condivisa e distribuita e per sistematizzare la conoscenza presente su Internet. Nel terzo capitolo viene descritta una soluzione software basata sull'utilizzo di tecnologie semantiche in grado di classificare automaticamente i documenti sul Web sulla base delle risorse presenti in DBpedia. Sono esposti il funzionamento e la metodologia del software TellMeFirst (http://tellmefirst.polito.it), sviluppato dal tesista nell'arco del 2011-2012 all'interno del Dipartimento di Automatica ed Informatica del Politecnico di Torino e in virtù di un grant Working Capital da parte di Telecom Italia. Nel quarto capitolo è delineato un possibile scenario futuro, frutto di questo processo di classificazione. Ogni concetto presente in Wikipedia diventa un Gateway per un insieme di documenti ordinati secondo la loro attinenza all'argomento stesso. Ognuno di questi Gateway si può configurare come un motore di ricerca semantico su un sottoinsieme di documenti del Web, dove si possono effettuare ricerche specifiche per sottoargomento o per argomenti correlati. I DBpedia Gateways possono essere contenuti o linkati direttamente nelle pagine di Wikipedia, come punto di partenza per approfondire un argomento specific

Diagnostics of the tropical tropopause layer from in-situ observations and CCM data

A suite of diagnostics is applied to in-situ aircraft measurements and one Chemistry-Climate Model (CCM) data to characterize the vertical structure of the Tropical Tropopause Layer (TTL). The diagnostics are based on vertical tracer profiles and relative vertical tracer gradients, using tropopause-referenced coordinates, and tracer-tracer relationships in the tropical Upper Troposphere/Lower Stratosphere (UT/LS). Observations were obtained during four tropical campaigns performed from 1999 to 2006 with the research aircraft Geophysica and have been compared to the output of the ECHAM5/MESSy CCM. The model vertical resolution in the TTL (~500 m) allows for appropriate comparison with high-resolution aircraft observations and the diagnostics used highlight common TTL features between the model and the observational data. The analysis of the vertical profiles of water vapour, ozone, and nitrous oxide, in both the observations and the model, shows that concentration mixing ratios exhibit a strong gradient change across the tropical tropopause, due to the role of this latter as a transport barrier and that transition between the tropospheric and stratospheric regimes occurs within a finite layer. The use of relative vertical ozone and carbon monoxide gradients, in addition to the vertical profiles, helps to highlight the region where this transition occurs and allows to give an estimate of its thickness. The analysis of the CO-O3 and H2O-O3 scatter plots and of the Probability Distribution Function (PDF) of the H2O-O3 pair completes this picture as it allows to better distinguish tropospheric and stratospheric regimes that can be identified by their different chemical composition. The joint analysis and comparison of observed and modelled data allows to state that the model can represent the background TTL structure and its seasonal variability rather accurately. The model estimate of the thickness of the interface region between tropospheric and stratospheric regimes agrees well with average values inferred from observations. On the other hand, the measurements can be influenced by regional scale variability, local transport processes as well as deep convection, that can not be captured by the model

Diagnostics of the tropical tropopause layer from in-situ observations and CCM data

A suite of diagnostics is applied to in-situ aircraft measurements and one Chemistry-Climate Model (CCM) data to characterize the vertical structure of the Tropical Tropopause Layer (TTL). The diagnostics are based on the vertical tracers profiles, relative vertical tracers gradients, and tracer-tracer relationships in the tropical Upper Troposphere/Lower Stratosphere (UT/LS), using tropopause coordinates. Observations come from the four tropical campaigns performed from 1998 to 2006 with the research aircraft Geophysica and have been directly compared to the output of the ECHAM5/MESSy CCM. The model vertical resolution in the TTL allows for appropriate comparison with high-resolution aircraft observations and the diagnostics used highlight common TTL features between the model and the observational data. The analysis of the vertical profiles of water vapour, ozone, and nitrous oxide, in both the observations and the model, shows that concentration mixing ratios exhibit a strong gradient change across the tropical tropopause, due to the role of this latter as a transport barrier and that transition between the tropospheric and stratospheric regimes occurs within a finite layer. The use of relative vertical ozone gradients, in addition to the vertical profiles, helps to highlight the region where this transition occurs and allows to give an estimate of its thickness. The analysis of the CO-O3 and H2O-O3 scatter plots and of the Probability Distribution Function (PDF) of the H2O-O3 pair completes this picture as it allows to better distinguish tropospheric and stratospheric regimes that can be identified, first, by their differing chemical composition. The joint analysis and comparison of observed and modelled data allows us to evaluate the capability of the model in reproducing the observed vertical structure of the TTL and its variability, and also to assess whether observations from particular regions on a monthly timescale can be representative of the fine scale mean structure of the Tropical Tropopause Layer

Impact of deep convection in the tropical tropopause layer in West Africa: in-situ observations and mesoscale modelling

We present the analysis of the impact of convection on the composition of the tropical tropopause layer region (TTL) in West-Africa during the AMMA-SCOUT campaign. Geophysica M55 aircraft observations of water vapor, ozone, aerosol and CO2 show perturbed values at altitudes ranging from 14 km to 17 km (above the main convective outflow) and satellite data indicates that air detrainment is likely originated from convective cloud east of the flight. Simulations of the BOLAM mesoscale model, nudged with infrared radiance temperatures, are used to estimate the convective impact in the upper troposphere and to assess the fraction of air processed by convection. The analysis shows that BOLAM correctly reproduces the location and the vertical structure of convective outflow. Model-aided analysis indicates that in the outflow of a large convective system, deep convection can largely modify chemical composition and aerosol distribution up to the tropical tropopause. Model analysis also shows that, on average, deep convection occurring in the entire Sahelian transect (up to 2000 km E of the measurement area) has a non negligible role in determining TTL composition

Comparison of Antarctic polar stratospheric cloud observations by ground-based and space-borne lidar and relevance for chemistry–climate models

Abstract. A comparison of polar stratospheric cloud (PSC) occurrence from 2006 to 2010 is presented, as observed from the ground-based lidar station at McMurdo (Antarctica) and by the satellite-borne CALIOP lidar (Cloud-Aerosol Lidar with Orthogonal Polarization) measuring over McMurdo. McMurdo (Antarctica) is one of the primary lidar stations for aerosol measurements of the NDACC (Network for Detection of Atmospheric Climate Change). The ground-based observations have been classified with an algorithm derived from the recent v2 detection and classification scheme, used to classify PSCs observed by CALIOP. A statistical approach has been used to compare ground-based and satellite-based observations, since point-to-point comparison is often troublesome due to the intrinsic differences in the observation geometries and the imperfect overlap of the observed areas. A comparison of space-borne lidar observations and a selection of simulations obtained from chemistry–climate models (CCMs) has been made by using a series of quantitative diagnostics based on the statistical occurrence of different PSC types. The distribution of PSCs over Antarctica, calculated by several CCMVal-2 and CCMI chemistry–climate models has been compared with the PSC coverage observed by the satellite-borne CALIOP lidar. The use of several diagnostic tools, including the temperature dependence of the PSC occurrences, evidences the merits and flaws of the different models. The diagnostic methods have been defined to overcome (at least partially) the possible differences due to the resolution of the models and to identify differences due to microphysics (e.g., the dependence of PSC occurrence on T−TNAT). A significant temperature bias of most models has been observed, as well as a limited ability to reproduce the longitudinal variations in PSC occurrences observed by CALIOP. In particular, a strong temperature bias has been observed in CCMVal-2 models with a strong impact on PSC formation. The WACCM-CCMI (Whole Atmosphere Community Climate Model – Chemistry-Climate Model Initiative) model compares rather well with the CALIOP observations, although a temperature bias is still present

In situ measurements of tropical cloud properties in the West African Monsoon: upper tropospheric ice clouds, Mesoscale Convective System outflow, and subvisual cirrus

In situ measurements of ice crystal size distributions in tropical upper troposphere/lower stratosphere (UT/LS) clouds were performed during the SCOUT-AMMA campaign over West Africa in August 2006. The cloud properties were measured with a Forward Scattering Spectrometer Probe (FSSP-100) and a Cloud Imaging Probe (CIP) operated aboard the Russian high altitude research aircraft M-55 Geophysica with the mission base in Ouagadougou, Burkina Faso. A total of 117 ice particle size distributions were obtained from the measurements in the vicinity of Mesoscale Convective Systems (MCS). Two to four modal lognormal size distributions were fitted to the average size distributions for different potential temperature bins. The measurements showed proportionately more large ice particles compared to former measurements above maritime regions. With the help of trace gas measurements of NO, NOy, CO2, CO, and O3 and satellite images, clouds in young and aged MCS outflow were identified. These events were observed at altitudes of 11.0 km to 14.2 km corresponding to potential temperature levels of 346 K to 356 K. In a young outflow from a developing MCS ice crystal number concentrations of up to (8.3 ± 1.6) cm−3 and rimed ice particles with maximum dimensions exceeding 1.5 mm were found. A maximum ice water content of 0.05 g m−3 was observed and an effective radius of about 90 μm. In contrast the aged outflow events were more diluted and showed a maximum number concentration of 0.03 cm−3, an ice water content of 2.3 × 10−4 g m−3, an effective radius of about 18 μm, while the largest particles had a maximum dimension of 61 μm. Close to the tropopause subvisual cirrus were encountered four times at altitudes of 15 km to 16.4 km. The mean ice particle number concentration of these encounters was 0.01 cm−3 with maximum particle sizes of 130 μm, and the mean ice water content was about 1.4 × 10−4 g m−3. All known in situ measurements of subvisual tropopause cirrus are compared and an exponential fit on the size distributions is established for modelling purposes. A comparison of aerosol to ice crystal number concentrations, in order to obtain an estimate on how many ice particles may result from activation of the present aerosol, yielded low ratios for the subvisual cirrus cases of roughly one cloud particle per 30 000 aerosol particles, while for the MCS outflow cases this resulted in a high ratio of one cloud particle per 300 aerosol particles

Understanding the conformational changes and molecular structure of furoyl thioureas upon substitution

1-Acyl thioureas [R1C(O)NHC(S)NR2R3] are shown to display conformational flexibility depending on the degree of substitution at the nitrogen atom. The conformational landscape and structural features for two closely related thioureas having R1 = 2-furoyl have been studied. The un-substituted 2-furoyl thiourea (I) and its dimethyl analogue, i.e. 1-(2-furoyl)-3,3-dimethyl thiourea (II), have been synthesized and fully characterized by spectroscopic (FT-IR, 1H and 13C NMR) and elemental analysis. According to single crystal X-ray diffraction analysis, compounds I and II crystallize in the monoclinic space group P21/c. In the compound I, the trans–cis geometry of the almost planar thiourea unit is stabilized by intramolecular Nsingle bondH ⋯ Odouble bondC hydrogen bond between the H atom of the cis thioamide and the carbonyl O atom. In compound II, however, the acyl thiourea group is non-planar, in good agreement with the potential energy curve computed at the B3LYP/6-31 + G(d,p) level of approximation. Centrosymmetric dimers generated by intermolecular N — H ⋯ O = C hydrogen bond forming R22(8) motif are present in the crystals. Intermolecular interactions have been rationalized in terms of topological partitions of the electron distributions and Hirshfeld surface analysis, which showed the occurrence of S ⋯ H, O ⋯ H and H ⋯ H contacts that display an important role to crystal packing stabilization of both thiourea derivatives.Instituto de Física La PlataCentro de Química Inorgánic

Crónica

Comentario y reseña del XII Congreso de la FIEC (Ouro Preto, 2004), IX Encuentro Internacional de Estudios Clásicos (Creta, 2004), XVIII Simposio Nacional de Estudios Clásicos de la AADEC (Mar del Plata, 2004), Curso Internacional 2004 del Centro de Estudios Latinos, II Jornadas de Estudios Clásicos y Medievales (La Plata, 2005), curso del Dr. Aníbal Biglieri, "El emperador Trajano en la Estoria de Espanna de Alfonso X" (La Plata, 2005), XIII Jornadas de Estudios Clásicos (UCA, 2005), II Jornada Interdisciplinaria "Conociendo a Hildegarda, la abadesa de Bingen y su tiempo" (UCA, 2005), I Congreso Internacional de Estudios Clásicos en México (UNAM, 2005), Curso Internacional 2005 del Centro de Estudios Latinos, Coloquio Internacional de Teatro Latino (Rosario, 2005), XV Simposio de Estudios Clásicos de la SEEC (Lérida, 2005), Simposio Internacional "Artes, Ciencias y Letras en la América Colonial" (Biblioteca Nacional, 2005) y I Jornada de Estudios Clásicos "Ordia Prima" (Córdoba, 2005).Centro de Estudios Latino

Crónica

Comentario y reseña del XII Congreso de la FIEC (Ouro Preto, 2004), IX Encuentro Internacional de Estudios Clásicos (Creta, 2004), XVIII Simposio Nacional de Estudios Clásicos de la AADEC (Mar del Plata, 2004), Curso Internacional 2004 del Centro de Estudios Latinos, II Jornadas de Estudios Clásicos y Medievales (La Plata, 2005), curso del Dr. Aníbal Biglieri, "El emperador Trajano en la Estoria de Espanna de Alfonso X" (La Plata, 2005), XIII Jornadas de Estudios Clásicos (UCA, 2005), II Jornada Interdisciplinaria "Conociendo a Hildegarda, la abadesa de Bingen y su tiempo" (UCA, 2005), I Congreso Internacional de Estudios Clásicos en México (UNAM, 2005), Curso Internacional 2005 del Centro de Estudios Latinos, Coloquio Internacional de Teatro Latino (Rosario, 2005), XV Simposio de Estudios Clásicos de la SEEC (Lérida, 2005), Simposio Internacional "Artes, Ciencias y Letras en la América Colonial" (Biblioteca Nacional, 2005) y I Jornada de Estudios Clásicos "Ordia Prima" (Córdoba, 2005).Centro de Estudios Latino