National standardized tests database implemented as a research methodology in mathematics education. The case of algebraic powers.

International audienceIn this work we show the use of the INVALSI database as an instrument to collect organized data from national standardized tests in order to study students’ mathematical thinking on a large scale. It allows us to create appropriate correlations to single out the behavior of the students relative to a specific mathematical topic or a cognitive issue. In this study we have used the INVALSI database to study how grade 10 students work with powers in the domain of algebra. We analyze the quantitative data within a semiotic theoretical framework. Analyzing items taken from the INVALSI tests we are able to single out a general behavior that involves a population of Italian students and that persists in time. We interpret the results within our theoretical framework, thereby giving a quantitative validation to a theoretical perspective that has been proven consistent by qualitative investigations

National standardized tests database implemented as a research methodology in mathematics education. The case of algebraic powers.

International audienceIn this work we show the use of the INVALSI database as an instrument to collect organized data from national standardized tests in order to study students’ mathematical thinking on a large scale. It allows us to create appropriate correlations to single out the behavior of the students relative to a specific mathematical topic or a cognitive issue. In this study we have used the INVALSI database to study how grade 10 students work with powers in the domain of algebra. We analyze the quantitative data within a semiotic theoretical framework. Analyzing items taken from the INVALSI tests we are able to single out a general behavior that involves a population of Italian students and that persists in time. We interpret the results within our theoretical framework, thereby giving a quantitative validation to a theoretical perspective that has been proven consistent by qualitative investigations

Green Systems Integrated to the Building Envelope: Strategies and Technical Solution for the Italian Case

Green roofs and green and living walls are increasingly seen in cities, because they are an important strategy that addresses some key urban environmental issues and allows the achievement of different benefits. Among these, the most relevant ones are reduction of the \u201cUrban Heat Island\u201d effect, of rainfall contributions to the sewer system, of environmental impact and energy saving, and retention of harmful substance. The study aims to analyze different systems of greenery systems integrated (GSI), green roofs (GR), and green and living walls (GW-LW), as a possible retrofit technique of the envelope of heritage buildings and especially their applications in the context of historic cities in Italy, pointing out positive and negative aspects. Particularly, it pays attention to the green retrofitting of buildings and to the technical problems related to the installation of systems, since at the moment there are already several studies that show the environmental and microclimatic benefits of the integration of vegetation in architecture. This study tries to highlight the series of design procedures necessary both in the preliminary phase and then in the executive phase to relate the GSI to the existing building envelopes. The GR, from the results of the simulations conducted, demonstrate a greater simplicity in their construction, with improvements also from the point of view of the working loads on the existing structures, since the interventions are performed more easily than those on the facade. The study highlights the architectural needs that are not always considered such as the increase in the thickness of the roof and the related need to raise its edges, changing the perspective of the building. On the other hand, the GW and the LW show some complexity in their construction because they must deal with facades often rich in decorative elements and where openings aect the assemblage and connection works such as the tinsmiths of the intrados of the openings. It must be taken into consideration the necessity of having to drill masonry, often inhomogeneous, to connect fixings and the problems of stability this entails must be carefully analyzed

Endoscopic transsphenoidal approach as a promising surgical option in the treatment of craniopharyngioma

10.1530/endoabs.32.P85

PROGETTO “MESSINA 1908 – 2008”. RAPPORTO DELLA CAMPAGNA OBS NELL’AREA EOLIANA E DELLO STRETTO DI MESSINA

Il Centro Nazionale Terremoti (CNT), in collaborazione con la sezione di Catania, ha progettato e realizzato un esperimento di sismica passiva nell’area Calabro–Peloritana il cui scopo è fornire nuovi dati sismici volti a comprendere come le dinamiche superficiali ed il processo di subduzione interagiscano tra loro, migliorando così la comprensione dei processi sismogenetici nella zona colpita dal terremoto del 1908 [Margheriti et al., 2008; http://dpc-s5.rm.ingv.it]. Con l’obiettivo di ridurre l’errore di localizzazione degli ipocentri degli eventi verificatisi nell’area interessata dal progetto, ad integrazione delle 30 stazioni della rete sismica nazionale già presenti nell’area in esame, l’esperimento ha previsto l’installazione di 15 stazioni della rete mobile e la deposizione di 5 OBS/H (Ocean Bottom Seismometer with Hydrophone), per un numero complessivo di 50 stazioni sismiche larga banda 3C coinvolte nel progetto. La campagna sismica a terra ha avuto inizio nell’ottobre 2007 e ad oggi (gennaio 2009), le stazioni sono ancora in funzione, mentre la deposizione dei cinque OBS/H è avvenuta tra il 15 e il 18 luglio 2008 ed il loro recupero è stato effettuato tra il 6 e il 7 novembre 2008. Gli OBS/H, progettati e realizzati presso l’OBS Lab di Gibilmanna, sono stati equipaggiati con sismometri Nanometrics Trillium 120p (120s - 175 Hz) e con sensori differenziali di pressione (Differential Pressure Gauge) Cox-Webb, con banda passante tra i 200s e i 2Hz. La base autolivellante sulla quale è installato il sensore sismico è stata realizzata anch’essa presso l’OBS Lab di Gibilmanna nei mesi intercorsi tra il recupero degli OBS impiegati nella prima campagna NERIES, avvenuto nel marzo 2008, e il luglio 2008, data della deposizione degli OBS del progetto “Messina 1908 – 2008”. La necessità di realizzare una nuova base autolivellante in tempi così brevi, è stata una diretta conseguenza dei risultati negativi ottenuti dalla base Nautilus in occasione della già citata campagna NERIES [D’Anna et al., 2008]: due sismometri su tre non si erano livellati nel range di ±0.2°, massimo tilt dinamico previsto per i Trillium 120p, provocando il non funzionamento degli stessi. Come meglio verrà analizzato nei paragrafi successivi, le problematiche affrontate nella realizzazione di questi dispositivi di livellamento sono state molteplici e di difficile soluzione. L’analisi preliminare dei dati ha evidenziato che soltanto uno dei cinque sensori sismici ha funzionato correttamente per l’intero periodo, mentre gli altri quattro hanno funzionato in media per circa 20 giorni. Causa di ciò, un rapido consumo delle batterie dovuto ad un livellamento sì compreso nel range di ±0.2° dall’orizzontale, condizione necessaria perché il sismometro sia in grado di rilevare eventi sismici, ma oltre il range di ±0.1°, condizione necessaria perché i consumi del Trillium120p si riducano da circa 2.5W ai 600mW nominali. I risultati ottenuti da questo esperimento, sono comunque da inquadrare in una successione degli eventi che ha fatto sì che lo sviluppo di questa nuova base autolivellante fosse condizionato da una certa urgenza: al CNT premeva presentare i dati raccolti dagli OBS al convegno “Scienza e società a 100 anni dal grande Terremoto”, che si sarebbe tenuto a Reggio Calabria dal 10 al 12 dicembre 2008 e visti gli insuccessi della base Nautilus nel precedente esperimento, ci si è trovati di fronte alla necessità di progettare e sviluppare un nuovo sistema di livellamento per i Trillium 120p nell’arco di tre mesi e mezzo. Queste, oltre a quelle di natura economica, le ragioni per cui non è stato possibile procedere secondo un iter che per noi, come per le aziende che operano nel settore marino, è uno standard: - Progettazione; - Realizzazione del prototipo; - Test in laboratorio (e. g. tavola vibrante) - Test in camera iperbarica; - Test in mare; - Produzione in serie; E’ nostra intenzione, in un prossimo futuro, portare avanti lo sviluppo di questa base autolivellante, con tempi e risorse finanziare ed umane più appropriate. Ciò che riportiamo in questo Rapporto Tecnico vuole essere una descrizione del lavoro sin qui svolto, anche se non conclusivo e risolutivo, ma che ci ha già permesso di individuare delle problematiche fondamentali la cui soluzione sarà oggetto di studi più approfonditi. Rimane positivo il fatto che le basi già realizzate riescono già da adesso a livellare automaticamente un sensore entro un range di ±0.2°. Gli OBS/H dell’INGV verranno nuovamente deposti con la stessa disposizione del progetto “Messina 1908 – 2008” nell’estate 2009, nell’ambito del progetto S5 finanziato dal Dipartimento della Protezione Civile. Per sopperire alle problematiche riscontrate nella marinizzazione del Trillium 120p, si è scelto di installare a bordo degli OBS dei sensori Guralp CMG40T-OBS (60s – 100 Hz), progettati per installazioni in mare sino a profondità di 6000 m è già dotati di una propria base autolivellante. Il motivo per il quale non si è utilizzato nelle passate campagne questo tipo di sensore è da addebitare unicamente al fatto che sui fondi DPC della convenzione 2005-2007 non è stato possibile inserire l’acquisto di questi specifici sensori, mentre erano disponibili i Trillium 120p

Effect of Fuel Ethanol Content on Exhaust Emissions of a Flexible Fuel Vehicle

The European Union is aiming at increasing the market share of biofuels in order to improve the security of supply of transport fuel and to reduce CO2 emissions. The target is to reach a 10% of biofuels on energy basis in the transport sector by 2020. Bioethanol and biodiesel represent the only biofuels currently available on the market in big quantities and technologically mature and bioethanol is probably the most widely use alternative fuel in the world (mainly in Brazil and in the USA). According to the literature, the success of bioethanol as alternative fuel is linked to some clear advantages but there are also disadvantages: Advantages: - Very high octane number - As a renewable fuel produces lower CO2 emissions compare to conventional fuels - It reduces some pollutant emissions - Its ozone forming potential is lower than that of gasoline and diesel - It contains no sulphur and is biodegradable Disadvantages: - It increases evaporative emissions (when blended with gasoline at low percentages) - Because of the lower vapour pressure and high latent heat of vaporization of neat ethanol, it makes cold start in cooler climates more difficult. - It increase acetaldehyde emissions but reduces those of formaldehyde. - E85 vehicles give higher unregulated emissions (ethane and acetaldehyde) than gasoline fuelled vehicles. Due to its characteristics neat ethanol cannot be used as transport fuel mainly because its high heat of vaporization and low volatility make cold start very difficult especially in cold climates. The most common way to overcome this problem is to blend ethanol with a small fraction of a much more volatile fuel such as gasoline; the most popular blend is E85 which consists of 85% ethanol and 15% gasoline by volume. Although E85 has been extensively used worldwide, engine manufacturers guarantee problem-free operation without any modification only to catalyst equipped cars fuelled with gasoline containing no more than 5% ethanol. However modern catalyst-equipped cars are probably able to run without any material problem with up to 20% ethanol which seems to be the upper limit for cold climates. An experimental activity has been planned and carried out at the JRC to investigate the emissions of a flexible fuel vehicle using different ethanol/gasoline blends. The results of this experimental programme are briefly summarized here below. The details of the work and the complete results are described in the first part of this document ( In particular, three different fuels have been tested: a standard commercial summer gasoline marketed in Italy used as base fuel and two gasoline/ethanol blends, which have been obtained by splash blending ethanol in the standard gasoline. The two gasoline/ethanol blends contained respectively 10% ethanol (E10) and 85% ethanol (E85). The test vehicle was a passenger car currently marketed in Europe and one of the most popular models belonging to the flexible fuel vehicle category. Emission tests were carried out both following the European certification procedure (NEDC cycle) and using a US driving cycle (US 06). Regulated and unregulated emissions were measured.JRC.H.4-Transport and air qualit

Effect of Biodiesel Fuels on Pollutant Emissions from EURO 3 LD Diesel Vehicles (1)

Transport is a key factor in modern economies. However, the EU transport system is currently not sustainable, and in many respects moving away from sustainability rather than towards it. The European Environment Agency highlights in particular the sector's growing CO2 emissions that threaten the EU meeting its target under the Kyoto protocol. Transport also represents a key challenge to sustainability in terms of depletion of resources and European competitiveness, safety and security concerns, especially due to the monolithic reliance on a single energy source. As stated in the Commission’s November 2000 Green Paper on security of supply, in 1998 energy consumption in the transport sector was to blame for 28 % of emissions of CO2, the leading greenhouse gas. In particular, road transport alone accounts for 84 % of the CO2 emissions attributable to transport. Furthermore, in terms of security of energy supply, there is growing concern for the current situation of transport sector that depends on crude oil for more than 99%. In the above mentioned Green Paper the European Commission has also identified the measures to tackle these problems and, among them, one the most important is the promotion of alternative fuels; the ambitious target that has been proposed by the Commission is to replace 20% of conventional fuels with substitute fuels by 2020. According to the Commission White Paper “European transport policy for 2010: time to decide” the most promising forms are biofuels in the short and medium term, natural gas in the medium and long term and hydrogen in the very long term. On the basis of the above mentioned Papers, in 2003 the European Union has adopted two Directives, the EC/2003/30 and the EC/2003/96, with the overall objective of promoting the use of biofuels. The first Directive set the targets for market share of biofuels for 2005 (2% in terms of energy content) and 2010 (5.75%); the second Directive set the framework for tax incentives for the promotion of biofuels. Biodiesel is currently the most produced biofuel in Europe: the production in 2003 was about of 1500000 (EU25) tons with an increase of more than 32% compared to the 2002 figure. Within this policy framework, the Joint Research Centre and the European Biodiesel Board have decided to cooperate to investigate the effect of biodiesel on pollutant emissions from diesel engines. In particular, in this report the effect of biodiesel fuels produced from different raw materials on the regulated emissions from light duty diesel vehicles are compared to the effect on other regulated and unregulated pollutants.JRC.H.4-Transport and air qualit

Architettura, tradizione e recupero in un centro storico minore del Friuli Venezia Giulia

We propose the result of a prolonged research work developed, relating to traditional vernacular architectures characterizing minor contexts. The focus of the contribution concerns in particular the territorial area of Valcellina (Pn) characterized by historical and environmental specificities. From a common elementary typological matrix attributable to the paradigm of the pre-Alpine house, the building heritage has evolved into a series of variants that have determined its progressive adaptation to economic and environmental conditions. From a common elementary typological matrix attributable to the paradigm of the pre-Alpine house, the building heritage has evolved into a series of variants that have determined its progressive adaptation to economic and environmental conditions. In the smaller centers scattered along the valley the aggregation processes of the primitive bicellular units are readable, with redefinition of the vertical connection paths, of subdivision into single-cell units (columnar houses at Andreis), of progressive closure of the balconies with the generation of a subsequent type (loggia house) most present, above all for climatic reasons in the upper part of the valley, but with different connotations than the similar constructions of nearby Carnia. The study clearly shows how the spontaneous conscience of the settled population is reflected in the constructive culture and as a consequence this remains with the changing environmental contexts