831 research outputs found

    THE TEACHING APPROACH TO GEOSCIENCES IN EARLY ITALIAN HIGH SCHOOL: RECENT TRENDS AND NEW PERSPECTIVES.

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    Nel Settembre del 2010 entrava in vigore in Italia la riforma della scuola secondaria superiore. Col nuovo quadro normativo venivano introdotte importanti novit\ue0 nell\u2019insegnamento delle Scienze Naturali sensu latu. Tra queste una delle pi\uf9 rilevanti \ue8 consistita nell\u2019introduzione dello studio delle Geoscienze nei curricola dei licei gi\ue0 a partire dal primo anno e da insegnarsi in parallelo con la biologia e la chimica per tutti e cinque gli anni. Questa piccola rivoluzione nell\u2019ambito dell\u2019istruzione scientifica liceale, nel volgere di pochi anni oltre a toccare centinaia di migliaia di giovani studenti, ha da un lato coinvolto massicciamente autori di libri di testo ed editori chiamati a produrre nel pi\uf9 breve tempo possibile nuovi manuali in linea con le indicazioni nazionali, dall\u2019altro ha imposto ai docenti italiani la revisione di alcune prassi di lavoro consolidate, ma nello stesso tempo si \ue8 presentata come un\u2019occasione di sperimentazione e di innovazione. Nell\u2019ambito di questo mutato contesto normativo e didattico si \ue8 articolato il progetto del dottorato. Obiettivo della prima parte della ricerca \ue8 stato quello di fare luce sull\u2019impatto che la riforma ha esercitato nella realt\ue0 italiana a pi\uf9 livelli: quello degli autori/editori di testi scolastici, quello degli insegnanti e quello degli studenti. La prima fase della ricerca ha messo in luce una diffusa difficolt\ue0 della classe docente italiana a mettere in pratica le indicazioni nazionali per il primo anno, per quel che concerne la trattazione dello studio della superficie terrestre da un punto di vista geomorfologico (il 25% del curricolo). Tale parte, dall\u2019esame dei programmi svolti al primo anno di un campione di docenti preso su tutto il territorio nazionale risulta, se non del tutto assente, molto marginalizzata. Nelle scelte di programmazione si legge piuttosto la tendenza a conservare prassi didattiche consolidate nel tempo anche se queste comportino la proposizione di temi non previsti dalle indicazioni della riforma (ad es. elementi di astrofisica). A questo dato fa eco quello sui libri di testo di Geoscienze pi\uf9 adottati nelle prime classi: a parte poche eccezioni, si tratta di manuali privi di un evidente strutturazione incentrata sullo studio delle forme del rilievo e dei processi coinvolti, mentre \ue8 privilegiato un taglio enciclopedico in cui figura una variet\ue0 di temi di gran lunga superiori a quelli richiesti dalle indicazioni nazionali. Per quanto riguarda il punto di vista degli studenti, abbiamo sottoposto ad un campione un questionario per valutare il grado di interesse e attitudine verso le Geoscienze maturato al momento del passaggio al Liceo. I dati suggeriscono che gli allievi arrivano dalla Scuola secondaria di primo grado dalle Medie con un elevato livello di interesse e adeguati prerequisiti per affrontarne lo studio. Inoltre \ue8 emerso che gli studenti mostrano una familiarit\ue0 verso le Geoscienze tanto pi\uf9 alta quanto pi\uf9 hanno praticato attivit\ue0 outdoor. Infatti invitati a indicare quali fossero le metodologie di apprendimento preferite nell\u2019affrontare tali discipline hanno indicato le attivit\ue0 di campo e di laboratorio al primo posto. E ci\uf2 nonostante la scuola figurasse nelle loro risposte, all\u2019ultimo posto come promotrice di esperienze di campo. Questi dati, insieme a quelli emersi da uno studio parallelo sull\u2019attitudine a progettare attivit\ue0 di campo da parte degli insegnanti di scienze in formazione, hanno suggerito la necessit\ue0 di cambiare paradigmi didattici. L\u2019ideazione e la sperimentazione di un diverso approccio didattico per lo svolgimento degli argomenti di Geoscienze del primo anno dei Licei costituiscono l\u2019ambito in cui si sviluppava la seconda fase del progetto del dottorato. In tale contesto, per trovare delle soluzioni agli ostacoli incontrati dai docenti in servizio nel portare a termine quanto previsto dalle indicazioni nazionali, veniva ideato e testato, insieme ad un campione di docenti e loro studenti, un modulo per l\u2019insegnamento della lettura del paesaggio basato su un approccio di tipo investigativo. Specificamente veniva effettuato uno studio quali-quantitativo di natura esplorativa, per mezzo di questionari pre e post intervento didattico, in modo da misurare la fattibilit\ue0 e l\u2019impatto del modulo nel conseguimento degli obiettivi educativi. Dai dati \ue8 emerso che docenti e allievi sono unanimemente concordi nel ritenere il tipo di approccio sperimentato molto pi\uf9 efficace nel promuovere interesse e attitudine verso gli argomenti di Geoscienze in oggetto, cos\uec come nel motivare allo studio, rispetto ad uno pi\uf9 tradizionale. Nel complesso, i risultati presentati in questa tesi fanno luce sull\u2019impatto che la cosiddetta riforma Gelmini ha esercitato sulla prassi didattica delle Geoscienze al primo anno della scuola superiore italiana e al contempo costituiscono un contributo per capire l\u2019influenza che l\u2019adozione di un approccio didattico di tipo investigativo pu\uf2 assumere nel promuovere l\u2019insegnamento e l\u2019apprendimento dello studio delle forme del paesaggio e dei processi ad esse connesse, in precedenza mai sperimentato nel contesto italiano.In September 2010, a new high school reform came into force in Italy. The new regulatory framework introduced significant changes in the teaching of Natural Sciences. One of the most relevant of these changes is the introduction of Geosciences topics in high school programs from the first school year, to be taught together with biology and chemistry through all the five years of secondary school. In a few years, this small revolution in the field of the high school\u2019s scientific education, other than concerning hundreds of thousands of young students, has in a way heavily involved text authors and editors responsible of producing, in the shortest time possible, new textbooks consistent with national guidelines, and on the other way has imposed to Italian teachers the revision of consolidated working routines. At the same time this reform has presented itself as an occasion to innovate and to experiment new didactic path. This PhD project has been developed in the range of this modified regulatory, as well as educational context. The main target of the first part of this research has been to show the effect of the reform on the Italian reality on various levels: that of authors/editors of textbooks, that of teachers and that of students. The first phase of this research has enlightened a widespread difficulty for Italian in-service teachers in putting into practice national guidelines for the first school year, for what concerns topics regarding Earth\u2019s surface considered from a geomorphological point of view (25% of the curriculum). The aforementioned topic, if examining the school programmes conducted during the first year by a sample of teachers over the whole national territory, is, if not totally absent, very marginalized. On the contrary, in the choice of said programmes we can read a tendency of preserving teaching routines consolidated in time, even if these propose topics not contemplated by the reform guidelines (for example astrophysics topics). These data fully reflect the ones concerning Geosciences textbooks most popularly adopted in first year classes: with a few exceptions, we find textbooks lacking a structure comprehending the study of geographical features and shapes and the processes involved therein, while an encyclopaedic structure is preferred, presenting a variety of topics much more abundant than those required by national guidelines. For what concerns a student\u2019s point of view, we conducted a questionnaire survey to evaluate the interest and attitude towards learning Geosciences that a sample of Italian students might have matured in the transition from lower to upper secondary school. Our data suggest that lower secondary school exposure to Geosciences promotes a great interest in the subject area, as well as a comfort level in the subject at the entrance to the Lyceum. Furthermore, the analysis also pointed out that students have a higher probability of showing a high awareness on Geosciences topics if they frequently undertake outdoor activities. Students were also asked which didactic methods they preferred in learning Geosciences; their answer to our questionnaires indicated a clear preference for practical and in-field activities, rather than traditional frontal lecture approaches. Nevertheless, the school was included in their answers at the last place as a promoter of field experiences. These results, together with those emerged from a parallel study on pre-service science teachers\u2019 attitude in planning field trips for Geosciences learning at secondary level, suggested the need to change the teaching paradigms. As a consequence, the second phase of the doctoral project focused on the design and testing of a new didactic path for the 1st year scheduled Geosciences contents. Thus, to find solutions to the difficulties encountered by in-service science teachers in responding to the reform\u2019s national guidelines, an educational module focussed on the reading of the landscape with an inquire-based approach was devised and tested with a sample of Italian High school teachers and their students. A qualitative - quantitative explorative case-study was run by collecting data with pre-and post intervention questionnaire aiming to shed light on some aspects of module\u2019s effectiveness. According to answers, Teachers and students are unanimous in judging the employment of this kind of approach in learning as a promoter of greater interest and inclination towards Geosciences treated topics and a greater stimulation to study these subjects compared to a traditional approach. In conclusion, the results presented in this thesis shed light on the impact of the so called Gelmini reform on the Italian Geosciences teaching and learning praxis at the first year of high school and represent a contribution for a better understanding of the impact of Inquiry based approaches in the learning of Earth landforms and related geomorphic processes which had never been implemented before in the Italian context

    Effects of glucagon on the growth of Neurospora

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    Effects of glucagon on the growth of Neurospora

    Extracting the three- and four-graviton vertices from binary pulsars and coalescing binaries

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    Using a formulation of the post-Newtonian expansion in terms of Feynman graphs, we discuss how various tests of General Relativity (GR) can be translated into measurement of the three- and four-graviton vertices. In problems involving only the conservative dynamics of a system, a deviation of the three-graviton vertex from the GR prediction is equivalent, to lowest order, to the introduction of the parameter beta_{PPN} in the parametrized post-Newtonian formalism, and its strongest bound comes from lunar laser ranging, which measures it at the 0.02% level. Deviation of the three-graviton vertex from the GR prediction, however, also affects the radiative sector of the theory. We show that the timing of the Hulse-Taylor binary pulsar provides a bound on the deviation of the three-graviton vertex from the GR prediction at the 0.1% level. For coalescing binaries at interferometers we find that, because of degeneracies with other parameters in the template such as mass and spin, the effects of modified three- and four-graviton vertices is just to induce an error in the determination of these parameters and, at least in the restricted PN approximation, it is not possible to use coalescing binaries for constraining deviations of the vertices from the GR prediction.Comment: 10 pages, 5 figures; v2: an error corrected; references adde

    Aligned Spins: Orbital Elements, Decaying Orbits, and Last Stable Circular Orbit to high post-Newtonian Orders

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    In this article the quasi-Keplerian parameterisation for the case that spins and orbital angular momentum in a compact binary system are aligned or anti-aligned with the orbital angular momentum vector is extended to 3PN point-mass, next-to-next-to-leading order spin-orbit, next-to-next-to-leading order spin(1)-spin(2), and next-to-leading order spin-squared dynamics in the conservative regime. In a further step, we use the expressions for the radiative multipole moments with spin to leading order linear and quadratic in both spins to compute radiation losses of the orbital binding energy and angular momentum. Orbital averaged expressions for the decay of energy and eccentricity are provided. An expression for the last stable circular orbit is given in terms of the angular velocity type variable xx.Comment: 30 pages, 2 figures, v2: update to match published versio

    Complete phenomenological gravitational waveforms from spinning coalescing binaries

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    The quest for gravitational waves from coalescing binaries is customarily performed by the LIGO-Virgo collaboration via matched filtering, which requires a detailed knowledge of the signal. Complete analytical coalescence waveforms are currently available only for the non-precessing binary systems. In this paper we introduce complete phenomenological waveforms for the dominant quadrupolar mode of generically spinning systems. These waveforms are constructed by bridging the gap between the analytically known inspiral phase, described by spin Taylor (T4) approximants in the restricted waveform approximation, and the ring-down phase through a phenomenological intermediate phase, calibrated by comparison with specific, numerically generated waveforms, describing equal mass systems with dimension-less spin magnitudes equal to 0.6. The overlap integral between numerical and phenomenological waveforms ranges between 0.95 and 0.99.Comment: Proceeding for the GWDAW-14 conference. Added reference in v

    All-sky search of NAUTILUS data

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    A search for periodic gravitational-wave signals from isolated neutron stars in the NAUTILUS detector data is presented. We have analyzed half a year of data over the frequency band Hz,thespindownrange Hz, the spindown range Hz/s and over the entire sky. We have divided the data into 2 day stretches and we have analyzed each stretch coherently using matched filtering. We have imposed a low threshold for the optimal detection statistic to obtain a set of candidates that are further examined for coincidences among various data stretches. For some candidates we have also investigated the change of the signal-to-noise ratio when we increase the observation time from two to four days. Our analysis has not revealed any gravitational-wave signals. Therefore we have imposed upper limits on the dimensionless gravitational-wave amplitude over the parameter space that we have searched. Depending on frequency, our upper limit ranges from 3.4×10233.4 \times 10^{-23} to 1.3×10221.3 \times 10^{-22}. We have attempted a statistical verification of the hypotheses leading to our conclusions. We estimate that our upper limit is accurate to within 18%.Comment: LaTeX, 12 page

    Effective field theory analysis of the self-interacting chameleon

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    We analyse the phenomenology of a self-interacting scalar field in the context of the chameleon scenario originally proposed by Khoury and Weltman. In the absence of self-interactions, this type of scalar field can mediate long range interactions and simultaneously evade constraints from violation of the weak equivalence principle. By applying to such a scalar field the effective field theory method proposed for Einstein gravity by Goldberger and Rothstein, we give a thorough perturbative evaluation of the importance of non-derivative self-interactions in determining the strength of the chameleon mediated force in the case of orbital motion. The self-interactions are potentially dangerous as they can change the long range behaviour of the field. Nevertheless, we show that they do not lead to any dramatic phenomenological consequence with respect to the linear case and solar system constraints are fulfilled.Comment: 15 pages, 2 figures. Final version accepted for publication on General Relativity and Gravitatio

    Towards a generic test of the strong field dynamics of general relativity using compact binary coalescence: Further investigations

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    In this paper we elaborate on earlier work by the same authors in which a novel Bayesian inference framework for testing the strong-field dynamics of General Relativity using coalescing compact binaries was proposed. Unlike methods that were used previously, our technique addresses the question whether one or more 'testing coefficients' (e.g. in the phase) parameterizing deviations from GR are non-zero, rather than all of them differing from zero at the same time. The framework is well-adapted to a scenario where most sources have low signal-to-noise ratio, and information from multiple sources as seen in multiple detectors can readily be combined. In our previous work, we conjectured that this framework can detect generic deviations from GR that can in principle not be accomodated by our model waveforms, on condition that the change in phase near frequencies where the detectors are the most sensitive is comparable to that induced by simple shifts in the lower-order phase coefficients of more than a few percent (5\sim 5 radians at 150 Hz). To further support this claim, we perform additional numerical experiments in Gaussian and stationary noise according to the expected Advanced LIGO/Virgo noise curves, and coherently injecting signals into the network whose phasing differs structurally from the predictions of GR, but with the magnitude of the deviation still being small. We find that even then, a violation of GR can be established with good confidence.Comment: 15 pages, 7 figures, Amaldi 9 proceeding

    IGEC2: A 17-month search for gravitational wave bursts in 2005-2007

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    We present here the results of a 515 days long run of the IGEC2 observatory, consisting of the four resonant mass detectors ALLEGRO, AURIGA, EXPLORER and NAUTILUS. The reported results are related to the fourfold observation time from Nov. 6 2005 until Apr. 14 2007, when Allegro ceased its operation. This period overlapped with the first long term observations performed by the LIGO interferometric detectors. The IGEC observations aim at the identification of gravitational wave candidates with high confidence, keeping the false alarm rate at the level of 1 per century, and high duty cycle, namely 57% with all four sites and 94% with at least three sites in simultaneous observation. The network data analysis is based on time coincidence searches over at least three detectors: the four 3-fold searches and the 4-fold one are combined in a logical OR. We exchanged data with the usual blind procedure, by applying a unique confidential time offset to the events in each set of data. The accidental background was investigated by performing sets of 10^8 coincidence analyses per each detector configuration on off-source data, obtained by shifting the time series of each detector. The thresholds of the five searches were tuned so as to control the overall false alarm rate to 1/century. When the confidential time shifts was disclosed, no gravitational wave candidate was found in the on-source data. As an additional output of this search, we make available to other observatories the list of triple coincidence found below search thresholds, corresponding to a false alarm rate of 1/month.Comment: 10 pages, 8 figures Accepted for publication on Phys. Rev.
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