163 research outputs found

    Circular geodesics and thick tori around rotating boson stars

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    Accretion disks play an important role in the evolution of their relativistic inner compact objects. The emergence of a new generation of interferometers will allow to resolve these accretion disks and provide more information about the properties of the central gravitating object. Due to this instrumental leap forward it is crucial to investigate the accretion disk physics near various types of inner compact objects now to deduce later constraints on the central objects from observations. A possible candidate for the inner object is the boson star. Here, we will try to analyze the differences between accretion structures surrounding boson stars and black holes. We aim at analysing the physics of circular geodesics around boson stars and study simple thick accretion tori (so-called Polish doughnuts) in the vicinity of these stars. We realize a detailed study of the properties of circular geodesics around boson stars. We then perform a parameter study of thick tori with constant angular momentum surrounding boson stars. This is done using the boson star models computed by a code constructed with the spectral solver library KADATH. We demonstrate that all the circular stable orbits are bound. In the case of a constant angular momentum torus, a cusp in the torus surface exists only for boson stars with a strong gravitational scalar field. Moreover, for each inner radius of the disk, the allowed specific angular momentum values lie within a constrained range which depends on the boson star considered. We show that the accretion tori around boson stars have different characteristics than in the vicinity of a black hole. With future instruments it could be possible to use these differences to constrain the nature of compact objects.Comment: Accepted for publication in CQ

    WP8 Modelling of topographic signal: GIS-BASED data base of potential earthquake sources identified in suitable kei-areas

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    GIS-based database of potential earthquake sources that were identified in key areas, such as the Provence, France, Po Plain, Italy, Outer Jura, Switzerland. The seismogenic source is defined as in Valensise and Pantosti (2001) following the scheme de-veloped in the framework of the EC project FAUST (Valensise et al., 2002)

    Vulcani: esplosioni ed effusioni

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    Si tratta dei pannelli realizzati per la mostraVulcani: Esplosioni ed effusioni Festival della Scienza di Genova 2007 Palazzo Ducale – Sottoporticato, Genova Una nuova mostra interattiva delll’Istituto Nazionale di Geofisica e Vucanologia, alla scoperta dei segreti del nostro pianeta e del mondo spettacolare dei vulcani. Organizzato come un “racconto”, è un lungo viaggio dalla nascita Terra ad oggi che aiuta a comprendere il ruolo fondamentale dei vulcani nella storia del nostro pianeta. Inizia con una proiezione 3d seguita da un filmato spettacolare e coinvolgente di eruzioni vulcaniche. Nella mostra si incontrano poi un grande modello di vulcano che può essere “acceso” in modalità interattiva, producendo un’eruzione esplosiva con gran fragore, sezioni di vulcano per scoprire “cosa c’è sotto”, plastici associati ad una speciale proiezione che permette di visualizzare sia l’eruzione sia l’interno del vulcano. E ancora rocce vulcaniche e un laboratorio per esperienze guidate, per capire il meccanismo che provoca l’eruzione, studiando il legame tra gas, pressione ed esplosione, anche utilizzando ulteriori modellini di vulcano. Il fatto che spesso le eruzioni vulcaniche siano accompagnate da attività sismica ci introduce alla parte finale della mostra, dedicata ai terremoti. L’obiettivo complessivo della mostra è quello di comunicare e far comprendere l’importanza del lavoro di ricerca e di controllo che svolge l’INGV e il riflesso che questo ha nella vita di ciascuno di noi. Si tratta, in sostanza, di “raccontare” le attività scientifiche svolte dall’Istituto inquadrandole dal punto di vista del visitatore.Con i contributi dell’Associazione per il Festival della Scienza e del Dipartimento della Protezione CivilePublished5.8. TTC - Formazione e informazionereserve

    Il progetto “O3E” I rischi naturali divulgati nella scuola per produrre conoscenza e consapevolezza

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    “O3E” (Observation de l’Environnement à but educatif dans les Écoles” ovvero osservazione dell'Ambiente a scopo educativo nella scuola) è un progetto transfrontaliero di educazione all’ambiente che raggruppa tre discipline (sismologia, meteorologia ed idrologia) ed è destinato agli allievi che frequentano le scuole primarie, medie ma soprattutto superiori nell’area delle Alpi latine. L'utilizzo di stazioni di misura nell'ambito delle scuole, delle attività pedagogiche “chiavi in mano”, il contatto tra scienziati ed insegnanti, un sito web che permette di visualizzare i dati “on line” ed il trasferimento transfrontaliero di conoscenze che riguardano l’educazione all’ambiente rappresentano le principali originalità del progetto “O3E”.Published48-491TM. Formazione2TM. Divulgazione ScientificaN/A or not JCRope

    Volcanoes: effusions and explosions. Interactive exhibits to understand how volcanoes work

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    The Educational & Outreach Group (EOG) of the Istituto Nazionale di Geofisica & Vulcanologia created a portable museum to provide educational opportunities in volcanology, volcanic risk and Earth science for students and visitors. The EOG developed this project for the "Festival della Scienza", organized in Genoa, Italy, in October - November, 2007, which was a parade of over 200 events, including scientific and technological exhibitions, workshops, meetings, lectures, books and video presentations. In this museum visitors can successively see many posters and movies and play with interactive exhibits. A little 3D-movie shows the Big Bang, the formation of Solar System and, in particular the formation of the Earth. Many interactive exhibits illustrate why, where and when earthquakes and volcanic eruptions occur around the world and allow to introduce the visitor to the plate tectonics theory. A 3D magnetic plate tectonic puzzle can be put down and reconstructed by visitors to understand the Earth’s surface configuration. Then two other 3D Earth models show what drives the plates and the inner Earth structure. An interactive program illustrates where and when earthquakes and volcanic eruptions occur in accelerated time on maps of various areas around the world. Playing with a block diagram it is possible to produce an earthquake along a 1 meter long strike slip fault in a destroying all the man-made constructions close to it. A little movie introduces to volcanoes’ world. Two small interactive exhibits allow visitors to understand the mechanism for the explosive and the effusive eruptions. Two other exciting interactive exhibits allow visitors to “create” two different eruptions: the explosive and the effusive ones. It is possible to get inside a volcano (a 2 meter high interactive exhibit) to attend an eruption from the magmatic chamber to the Earth surface. A big hall is completed dedicated to Italian volcanoes (Vesuvio, Campi Flegrei, Etna, Stromboli, Vulcano, Colli Albani); some of them are reproduced with 3D models or described by short movies. The museum finishes with the visit of the volcanic survey hall of Stromboli, seeing - in real time - seismic data, three different webcams, geochemical and strain data. The INGV Museum had remarkably successful, reaching more than 7,500 children and adults yet in 13 days, also thanks to 30 volcanologists as very special guides. The Educational & Outreach Group: M. Pignone, A. Tertulliani, M. De Lucia, M. Di Vito, P. Landi, P. Madonia, M. Martini, R. Nave, M. Neri, P. Scarlato, J. Taddeucci, R. Moschillo, S. Tarquini, G. Vilardo, A. Bonforte, L. Calderone, F. Cannavò, W. De Cesare, P. Ficeli, S. Inguaggiato, M. Mattia, G. Puglisi, S. Morici, D. Reitano, D. Richichi, G. Scarpato, B. Angioni, F. Di Laura, S. Palone, D. Riposat

    Identification of genes preferentially expressed in wheat egg cells and zygotes

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    Wheat genes differentially expressed in the egg cell before and after fertilization were identified. The data support zygotic gene activation before the first cell division in wheat. To have an insight into fertilization-induced gene expression, cDNA libraries have been prepared from isolated wheat egg cells and one-celled zygotes. Two-hundred and twenty-six egg cell and 253 zygote-expressed EST sequences were determined. Most of the represented transcripts were detected in the wheat egg cell or zygote transcriptome at the first time. Expression analysis of fourteen of the identified genes and three controls was carried out by real-time quantitative PCR. The preferential expression of all investigated genes in the female gametophyte-derived samples (egg cells, zygotes, two-celled proembryos, and basal ovule parts with synergids) in comparison to the anthers, and the leaves were verified. Three genes with putative signaling/regulatory functions were expressed at a low level in the egg cell but exhibited increased (2-to-33-fold) relative expression in the zygote and the proembryo. Genes with high EST abundance in cDNA libraries exhibited strong expression in the egg cell and the zygote, while the ones coding for unknown or hypothetical proteins exhibited differential expression patterns with preferential transcript accumulation in egg cells and/or zygotes. The obtained data support the activation of the zygotic genome before the first cell division in wheat

    A Powerful Method for Transcriptional Profiling of Specific Cell Types in Eukaryotes: Laser-Assisted Microdissection and RNA Sequencing

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    The acquisition of distinct cell fates is central to the development of multicellular organisms and is largely mediated by gene expression patterns specific to individual cells and tissues. A spatially and temporally resolved analysis of gene expression facilitates the elucidation of transcriptional networks linked to cellular identity and function. We present an approach that allows cell type-specific transcriptional profiling of distinct target cells, which are rare and difficult to access, with unprecedented sensitivity and resolution. We combined laser-assisted microdissection (LAM), linear amplification starting from <1 ng of total RNA, and RNA-sequencing (RNA-Seq). As a model we used the central cell of the Arabidopsis thaliana female gametophyte, one of the female gametes harbored in the reproductive organs of the flower. We estimated the number of expressed genes to be more than twice the number reported previously in a study using LAM and ATH1 microarrays, and identified several classes of genes that were systematically underrepresented in the transcriptome measured with the ATH1 microarray. Among them are many genes that are likely to be important for developmental processes and specific cellular functions. In addition, we identified several intergenic regions, which are likely to be transcribed, and describe a considerable fraction of reads mapping to introns and regions flanking annotated loci, which may represent alternative transcript isoforms. Finally, we performed a de novo assembly of the transcriptome and show that the method is suitable for studying individual cell types of organisms lacking reference sequence information, demonstrating that this approach can be applied to most eukaryotic organisms

    A Genome-Wide Survey of Imprinted Genes in Rice Seeds Reveals Imprinting Primarily Occurs in the Endosperm

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    Genomic imprinting causes the expression of an allele depending on its parental origin. In plants, most imprinted genes have been identified in Arabidopsis endosperm, a transient structure consumed by the embryo during seed formation. We identified imprinted genes in rice seed where both the endosperm and embryo are present at seed maturity. RNA was extracted from embryos and endosperm of seeds obtained from reciprocal crosses between two subspecies Nipponbare (Japonica rice) and 93-11 (Indica rice). Sequenced reads from cDNA libraries were aligned to their respective parental genomes using single-nucleotide polymorphisms (SNPs). Reads across SNPs enabled derivation of parental expression bias ratios. A continuum of parental expression bias states was observed. Statistical analyses indicated 262 candidate imprinted loci in the endosperm and three in the embryo (168 genic and 97 non-genic). Fifty-six of the 67 loci investigated were confirmed to be imprinted in the seed. Imprinted loci are not clustered in the rice genome as found in mammals. All of these imprinted loci were expressed in the endosperm, and one of these was also imprinted in the embryo, confirming that in both rice and Arabidopsis imprinted expression is primarily confined to the endosperm. Some rice imprinted genes were also expressed in vegetative tissues, indicating that they have additional roles in plant growth. Comparison of candidate imprinted genes found in rice with imprinted candidate loci obtained from genome-wide surveys of imprinted genes in Arabidopsis to date shows a low degree of conservation, suggesting that imprinting has evolved independently in eudicots and monocots
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