164 research outputs found
Complete Singular Collineations and Quadrics
We construct wonderful compactifications of the spaces of linear maps and symmetric linear maps of a given rank as blowups of secant varieties of Segre and Veronese varieties. Furthermore, we investigate their birational geometry and their relations with some spaces of degree two stable maps
IL BLOG INGVTERREMOTI: UN NUOVO STRUMENTO DI COMUNICAZIONE PER MIGLIORARE L’INFORMAZIONE SUI TERREMOTI DURANTE LA SEQUENZA SISMICA NELLA PIANURA PADANA
Durante una sequenza sismica è estremamente importante che la popolazione colpita dai terremoti abbia un’informazione tempestiva e continua sull’attività sismica in corso. Si genera un grande bisogno di informazione e di conoscenza da parte dei cittadini sulle caratteristiche
del fenomeno fisico, sulle sue cause e i suoi effetti, sui risultati degli studi preliminari, su quanto si
può fare per evitare situazioni di rischio, sulle iniziative messe in campo per gestire e superare l’emergenza. Questo bisogno è particolarmente rilevante in occasione di sequenze sismiche di lunga durata e che hanno un certo livello di complessità . Anche in occasione della sequenza simica attivatasi con il terremoto del 20 maggio 2012 (ore 02:03 UTC, ML 5.9) nella Pianura Padana,
l’esigenza di avere informazioni si è resa evidente. Ne è testimonianza l’enorme numero di visitatori e contatti ricevuti all’Home Page dell’INGV (http://www.ingv.it) con circa 610.000 visitatori il 20 maggio e circa 930.000 il 29 maggio, ma anche le centinaia di telefonate ed e-mail arrivati all’Istituto. Altra testimonianza la mole di tweet (interazione degli utenti con il canale
INGVterremoti su Twitter) relativi al terremoto che circolavano giĂ dagli istanti successivi alla
scossa del 20 maggio e successivamente per tutta la sequenza.
Anche durante la sequenza del 2009 a L’Aquila si era verificata una situazione simile. Infatti,
nei giorni successivi all’evento del 6 aprile 2009, grazie anche alla presenza del Centro Operativo
Emergenza Sismica a L’Aquila (Moretti et al., 2011), abbiamo capito che la richiesta, da parte delle
autoritĂ pubbliche e locali e dei cittadini, di informazioni complete e autorevoli, era piĂą elevata di
quanto si pensasse. In particolare, nelle situazioni di emergenza del 2009 e ancor piĂą del 2012, oltre
alle informazioni classiche sui siti web, molte persone hanno cercato informazioni e aggiornamenti
sui siti dei social media grazie anche alla diffusione di nuovi dispositivi tecnologici quali cellulari,
smartphone, tablet e notebook ultra-portatili.
Per rispondere a tale esigenza, pochi giorni dopo i primi eventi di maggio 2012 in Emilia
Romagna (20 maggio 2012 ore 02:03 UTC, ML 5.9, 29 maggio 2012 ore 07:00, ML 5.8; ore 10:55
ML 5.3; 11:00 ML 5.2) si è deciso di realizzare e aprire un nuovo canale informativo chiamato
INGVterremoti, un blog, (http://ingvterremoti.wordpress.com), attraverso il quale sono stati
pubblicati tantissimi aggiornamenti e approfondimenti scientifici sulla sequenza sismica in corso,
contemporaneamente alle informazioni fornite in tempo quasi reale attraverso i siti web istituzionali
dell’INGV.
Scopo principale del blog è stato quello di raccogliere in unico ambiente web tutta
l’informazione prodotta dai vari canali e siti web dell’INGV, sia orientati al pubblico che agli addetti
ai lavori. Il blog ha quindi aggregato il piĂą possibile i vari aggiornamenti dai siti istituzionali come
l’Home Page INGV (www.ingv.it), la pagina del Centro Nazionale Terremoti (http://cnt.rm.ingv.it)
e il database Iside (http://iside.rm.ingv.it) che forniscono informazioni sui terremoti recenti e notizie
piĂą specifiche e dettagliate sui terremoti storici (http://cpti11.mi.ingv.it) e sulla pericolositĂ sismica
(http://zonesismiche.mi.ingv.it). Inoltre il blog ha affiancato ai siti tradizionali anche l’informazione
proveniente dai canali sviluppati sul WEB 2.0 che negli ultimi due anni sono stati realizzati
dall’INGV con la denominazione comune di INGVterremoti. Tra il 2009 e il 2011, l’INGV infatti
ha iniziato a testare diversi social media, come YouTube, Twitter, Facebook e sviluppato
un’applicazione per iPhone, per rilasciare informazioni sui terremoti in tempo quasi reale ed
inserendo approfondimenti sulla pericolositĂ sismica e in generale sui terremoti. I social media
hanno dimostrato di essere molto importanti per le informazioni in caso di crisi (Bruns et al, 2012;
Earle et al., 2011), infatti per tutti questi nuovi canali di comunicazione, abbiamo osservato aumenti
significativi del numero di visualizzazioni e di download in corrispondenza di eventi sismici
risentiti dalla popolazione (Amato et al., 2012; Nostro et al., 2012). Sia i siti che i canali raggiungono centinaia di migliaia o milioni di contatti nel caso di forti terremoti: le persone possono trovare molte notizie specifiche sui singoli terremoti, sulla storia
sismica, ma durante questa emergenza è apparso evidente come non fosse ancora disponibile un
canale di informazione dove la gente potesse trovare aggiornamenti in tempi rapidi e spiegazioni
sulle attività in corso, con un linguaggio semplice ed efficace. Fornire notizie tempestive è
particolarmente importante nel caso di sequenze sismiche che durano diverse settimane e sono
caratterizzati da diverse scosse con magnitudo maggiore di 5.0, come nel caso dei terremoti della
Pianura Padana. Contemporaneamente alla gestione dell’emergenza, abbiamo lavorato per fornire
un’informazione scientificamente valida, costantemente aggiornata relativa a tutta l’area interessata
dalla sequenza, anche al fine di contrastare la cattiva informazione e combattere le voci, le dicerie,
i rumors
The INGVterremoti blog: a new communication tool to improve earthquake information during the Po Plain seismic sequence
The INGV sites that deliver information in quasi-realtime are well known. People often connect to the INGV home page (www.ingv.it), to the Centro Nazionale Terremoti (National Earthquake Centre) page (http://cnt.rm.ingv.it) and to the Italian Seismic Instrumental and Parametric
(ISIDe) database (http://iside.rm.ingv.it) to obtain information about recent earthquakes. Moreover, people look for more specific and detailed information on the historical
earthquake catalog (http://cpti11.mi.ingv.it), the seismic hazard web pages (http://zonesismiche.mi.ingv.it), the INGVterremoti YouTube channel (http://youtube.com/
ingvterremoti), the web-based macroseismic survey (http:// www.haisentitoilterremoto.it/) and others. For all of these sites, some of which are reached by hundreds of thousands,
or even millions people in cases of strong earthquakes, people can find a lot of specific information on individual earthquakes, on the seismic history, and so on. However, a place
where people could find updates and explanations on the ongoing activity was not available. When the Po Plain seismic sequence started on May 20, 2012, through the enormous
number of hits on the website of the INGV, to the many phone calls, emails and tweets, we soon realized that the request for information was huge. There were 0.61 and 0.93 million visits and 12 million and 26 million accesses on May 20 and 29, 2012, respectively. This was not a surprise, of
course, because also during the L'Aquila 2009 sequence there was a similar situation. Indeed, in the months after the April 6, 2009, event, also through the installation of the Centro
Operativo Emergenza Sismica (Seismic Emergency Operational Centre) in L'Aquila [Moretti et al. 2011], we understood that the request from the public and local authorities for complete and authoritative information was higher than had been previously thought. In particular, in the 2009 emergency, and even more so in the 2012 emergency, as well as classical information on web sites, many people looked for information and updates on social network sites. For this reason, between 2009 and 2011, the INGV started to test different social media, such as YouTube, Twitter, Facebook, and developed an application for the iPhone, to release earthquake information. Social media have proven to be very important for information sharing during crises [Earle et al.
2011, Bruns et al. 2012].
For all of these media, we observed relevant increases in the number of views and downloads corresponding to the important seismic events, when the attention was high [Amato et al. 2012, Nostro et al. 2012]. For this reason, in the days after the May 20, 2012, mainshock, we decided to open a new blog to provide quick updates and in-depth scientific information, such as articles on the ongoing seismic activity.
Providing timely information is particularly important when seismic sequences last for several weeks and are characterized by several M >5 events, as was the case of the Po Plain
earthquakes.
At the same time, we worked to provide fast, but scientifically sound, information, which was constantly updated and distributed throughout the territory, also to counter the bad information, and to fight rumors
Prediction of extreme events in the OFC model on a small world network
We investigate the predictability of extreme events in a dissipative
Olami-Feder-Christensen model on a small world topology. Due to the mechanism
of self-organized criticality, it is impossible to predict the magnitude of the
next event knowing previous ones, if the system has an infinite size. However,
by exploiting the finite size effects, we show that probabilistic predictions
of the occurrence of extreme events in the next time step are possible in a
finite system. In particular, the finiteness of the system unavoidably leads to
repulsive temporal correlations of extreme events. The predictability of those
is higher for larger magnitudes and for larger complex network sizes. Finally,
we show that our prediction analysis is also robust by remarkably reducing the
accessible number of events used to construct the optimal predictor.Comment: 5 pages, 4 figure
Object-action dissociation : a voxel-based lesion-symptom mapping study on 102 patients after glioma removal
Data concerning the neural basis of noun and verb processing are inconsistent. Some authors assume that action-verb processing is based on frontal areas while nouns processing relies on temporal regions; others argue that the circuits processing verbs and nouns are closely interconnected in a predominantly left-lateralized fronto-temporal-parietal network; yet, other researchers consider that the primary motor cortex plays a crucial role in processing action verbs. In the present study, one hundred and two patients with a tumour either in the right or left hemisphere were submitted to picture naming of objects and actions before and after surgery. To test the effect of specific brain regions in object and action naming, patients' lesions were mapped and voxel-lesion-symptom mapping (VLSM) was computed. Behavioural results showed that left-brain damaged patients were significantly more impaired than right brain-damaged patients. The VLSM showed that these two grammatical classes are segregated in the left hemisphere. In particular, scores in naming of objects correlated with damage to the anterior temporal region, while scores in naming of actions correlated with lesions in the parietal areas and in the posterior temporal cortex. In addition, VLSM analyses carried out on non-linguistic tasks were not significant, confirming that the regions associated with deficits in object and action naming were not generally engaged in all cognitive tasks. Finally, the involvement of subcortical pathways was investigated and the inferior longitudinal fasciculus proved to play a role in object naming, while no specific bundle was identified for actions
Identifiability for mixtures of centered Gaussians and sums of powers of quadratics
We consider the inverse problem for the polynomial
\nmap that sends an -tuple of quadratic forms in
\nvariables to the sum of their th powers. This map cap-
\ntures the moment problem for mixtures of centered
\n-variate Gaussians. In the first nontrivial case = 3,
\nwe show that for any \xe2\x88\x88 \xe2\x84\x95, this map is generically one-
\nto-one (up to permutations of 1 , \xe2\x80\xa6 , and third roots
\nof unity) in two ranges: \xe2\xa9\xbd (
\n2
\n) + 1 for < 16 and \xe2\xa9\xbd
\n(+5
\n6
\n)\xe2\x88\x95(+1
\n2
\n) \xe2\x88\x92 (+1
\n2
\n) \xe2\x88\x92 1 for \xe2\xa9\xbe 16, thus proving generic
\nidentifiability for mixtures of centered Gaussians from
\ntheir (exact) moments of degree at most 6. The first
\nresult is obtained by the explicit geometry of the tan-
\ngential contact locus of the variety of sums of cubes of
\nquadratic forms, as described by Chiantini and Ottaviani
\n[SIAM J. Matrix Anal. Appl. 33 (2012), no. 3, 1018\xe2\x80\x93
\n1037], while the second result is accomplished using the
\nlink between secant nondefectivity with identifiability,
\nproved by Casarotti and Mella [J. Eur. Math. Soc. (JEMS)
\n(2022)]. The latter approach also generalizes to sums of
\nth powers of -forms for \xe2\xa9\xbe 3 and \xe2\xa9\xbe 2
fMRI-Targeted High-Angular Resolution Diffusion MR Tractography to Identify Functional Language Tracts in Healthy Controls and Glioma Patients
Background
MR Tractography enables non-invasive preoperative depiction of language subcortical tracts, which is crucial for the presurgical work-up of brain tumors; however, it cannot evaluate the exact function of the fibers.
Purpose
A systematic pipeline was developed to combine tractography reconstruction of language fiber bundles, based on anatomical landmarks (Anatomical-T), with language fMRI cortical activations. A fMRI-targeted Tractography (fMRI-T) was thus obtained, depicting the subsets of the anatomical tracts whose endpoints are located inside a fMRI activation. We hypothesized that fMRI-T could provide additional functional information regarding the subcortical structures, better reflecting the eloquent white matter structures identified intraoperatively.
Methods
Both Anatomical-T and fMRI-T of language fiber tracts were performed on 16 controls and preoperatively on 16 patients with left-hemisphere brain tumors, using a q-ball residual bootstrap algorithm based on High Angular Resolution Diffusion Imaging (HARDI) datasets (b = 3000 s/mm(2); 60 directions); fMRI ROIs were obtained using picture naming, verbal fluency, and auditory verb generation tasks. In healthy controls, normalized MNI atlases of fMRI-T and Anatomical-T were obtained. In patients, the surgical resection of the tumor was pursued by identifying eloquent structures with intraoperative direct electrical stimulation mapping and extending surgery to the functional boundaries. Post-surgical MRI allowed to identify Anatomical-T and fMRI-T non-eloquent portions removed during the procedure.
Results
MNI Atlases showed that fMRI-T is a subset of Anatomical-T, and that different task-specific fMRI-T involve both shared subsets and task-specific subsets - e.g., verbal fluency fMRI-T strongly involves dorsal frontal tracts, consistently with the phonogical-articulatory features of this task. A quantitative analysis in patients revealed that Anatomical-T removed portions of AF-SLF and IFOF were significantly greater than verbal fluency fMRI-T ones, suggesting that fMRI-T is a more specific approach. In addition, qualitative analyses showed that fMRI-T AF-SLF and IFOF predict the exact functional limits of resection with increased specificity when compared to Anatomical-T counterparts, especially the superior frontal portion of IFOF, in a subcohort of patients.
Conclusion
These results suggest that performing fMRI-T in addition to the 'classic' Anatomical-T may be useful in a preoperative setting to identify the 'high-risk subsets' that should be spared during the surgical procedure
DARE: A Reflective Platform Designed to Enable Agile Data-Driven Research on the Cloud
The DARE platform has been designed to help research developers deliver user-facing applications and solutions over diverse underlying e-infrastructures, data and computational contexts. The platform is Cloud-ready, and relies on the exposure of APIs, which are suitable for raising the abstraction level and hiding complexity. At its core, the platform implements the cataloguing and execution of fine-grained and Python-based dispel4py workflows as services. Reflection is achieved via a logical knowledge base, comprising multiple internal catalogues, registries and semantics, while it supports persistent and pervasive data provenance. This paper presents design and implementation aspects of the DARE platform, as well as it provides directions for future development.PublishedSan Diego (CA, USA)3IT. Calcolo scientific
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