7,504 research outputs found
A WZW model based on a non-semi-simple group
We present a conformal field theory which desribes a homogeneous four
dimensional Lorentz-signature space-time. The model is an ungauged WZW model
based on a central extension of the Poincar\'e algebra. The central charge of
this theory is exactly four, just like four dimensional Minkowski space. The
model can be interpreted as a four dimensional monochromatic plane wave. As
there are three commuting isometries, other interesting geometries are expected
to emerge via duality.Comment: 8 pages, phyzzx, IASSNS-HEP-93/61 Texable versio
Lâuso della cartografia digitale come base per la realizzazione di un SIT dedicato alle reti sentieristiche in Campania: esempi ed applicazioni.
The development of the hiking paths network in the Campania Region, its marking and maintenance
in the field, as well as the relative cartographic restitution on up-to-date maps are nowadays
important objectives, since the naturalistic tourism in mountainous environment has recently become
more intense, and consequently it is necessary a correct and secure fruition of the hiking paths in the
various Campanian mountains groups. Therefore, it is important implementing a Geographical
Information System (GIS) dedicated to the Campanian hiking paths network with the aim of
process, storing and managing all the parameters and characteristics of the local paths, also during
time.
In this study some routes of naturalistic and environmental particular value have been selected,
which are located in the Lattari Mountains Group, the Vesuvius National Park and the Capri Island.
GPS field survey measurements have been carried out along these routes and stored using the
national official digital cartography. The field measurements have been taken during yearly
scheduled excursions of the Neapolitan section of the Italian Alpine Club. The acquired data have
been plotted on the relative maps, stored with the relative attributes tables and visualized through
Google Earth interactively.The obtained results represent a feasibility study for a GIS of the hiking paths network of the
Campania Region, with evident advantages and possible future developments not only for the
trekkers but also for environment protection goals
Bulk viscosity in 2SC and CFL quark matter
The bulk viscosities of two color-superconducting phases, the color-flavor
locked (CFL) phase and the 2SC phase, are computed and compared to the result
for unpaired quark matter. In the case of the CFL phase, processes involving
kaons and the superfluid mode give the largest contribution to the bulk
viscosity since all fermionic modes are gapped. In the case of the 2SC phase,
ungapped fermionic modes are present and the process u+d u+s provides the
dominant contribution. In both cases, the bulk viscosity can become larger than
that of the unpaired phase for sufficiently large temperatures (T >~ 1 MeV for
CFL, T >~ 0.1 MeV for 2SC). Bulk viscosity (as well as shear viscosity) is
important for the damping of r-modes in compact stars and thus can potentially
be used as an indirect signal for the presence or absence of
color-superconducting quark matter.Comment: 8 pages, 3 figures, contribution to the proceedings of QCD@Work 2007,
Martina Franca (Italy
VulnerabilitĂ del territorio vesuviano a fenomeni meteorologici attraverso lâanalisi quantitativa di fattori geologici ed antropici.
In questo lavoro viene descritta lâapplicazione al territorio vesuviano di una metodologia di analisi
geomorfologico-quantitativa multiparametrica da DTM (Digital Terrain Model) di dettaglio (5x5m)
in ambiente GIS, utilizzando procedure di analisi e tecniche di valutazione della vulnerabilitĂ a
fenomeni meteorologici che tengano conto della complessitĂ dellâassetto geologico,
geomorfologico, urbanistico ed economico dellâarea. Il risultato del lavoro Ăš stato la realizzazione
di mappe di vulnerabilitĂ idrogeologica prodotte tenendo conto delle mutue relazioni tra fattori
territoriali ed antropici.
Lâobiettivo di questo studio Ăš stato sviluppare un sistema di analisi utile alla valutazione del rischio
idrogeologico ed al suo controllo e prevenzione, considerato che negli ultimi anni si eâ assistito ad
incrementi rilevanti e disordinati dellâurbanizzazione nellâarea vesuviana, per la maggior parte
abusiva e con forti carenze strutturali, che, unitamente ad eventi piovosi particolarmente intensi
nonché alle caratteristiche geologico-geomorfologiche del territorio, hanno causato eventi franosi
parossistici come quelli dei comuni di Sarno, Episcopia e Bracigliano.
Lâarea di indagine, rappresentata dal complesso vulcanico del SommaâVesuvio in Campania, Ăš
densamente abitata (2500 abitanti per km2) ed oltre ad essere ad alto rischio vulcanico Ăš anche
esposta ad alto rischio idrogeologico come dimostrato dalle ripetute esondazioni disastrose fin
dallâepoca storica (Accardo et al., 1981; Catenacci et al., 1992).
La conoscenza dellâassetto geologico e geomorfologico del complesso Somma-Vesuvio Ăš
necessaria per una corretta individuazione dei parametri utili per questo studio. Un esempio Ăš quello
della caratterizzazione dei versanti del vulcano, fattore di notevole importanza per la valutazione del
rischio idrogeologico, sia per la pendenza che per le loro caratteristiche morfologiche superficiali.
Il primo parametro geomorfologico adottato per lâapplicazione della metodologia (Tagil and
Jenness, 2008) Ăš stato lâindice di posizione topografica (TPI, Topographic Position Index) che ha
consentito una classificazione del paesaggio sia in base alla distribuzione areale delle pendenze
(slope position) che in classi uniformi di paesaggio (landform classes). La classificazione finale Ăš
stata adeguata al particolare paesaggio oggetto di studio, che Ăš di tipo vulcanico.
Lâanalisi della vulnerabilitĂ Ăš stata condotta tenendo conto della permeabilitĂ del suolo e dei dati
pluviometrici in quanto possibili fattori predisponenti al dissesto idrogeologico.
Il GIS ha rappresentato lo strumento necessario per gestire dati di tipo diverso ed effettuarne
lâanalisi e la rappresentazione congiunta. Il software utilizzato Ăš stato ArcGis (9.3) e attraverso
lâapplicazione Spatial Analyst Ăš stato possibile estrarre dati ed informazioni nuove che non sarebbe
stato possibile ottenere con lâanalisi geomorfologica classica da cartografia su supporto cartaceo.
La realizzazione di mappe di vulnerabilitĂ idrogeologica dellâarea del Somma-Vesuvio, ottenute
stabilendo le relazioni tra i vari fattori incidenti con lâausilio di metodologie note (Cherubini et al.,
2006), ha rappresentato uno dei risultati del lavoro. Le interrelazioni tra i vari fattori (geologico,
geomorfologico, idrogeologico, urbanistico) mostrate dalle mappe prodotte costituiscono uno
strumento indispensabile per monitorare il rischio territoriale e per poter intervenire laddove venga
superata una soglia di rischio ritenuta accettabile
Progress in the development of a S RETGEM-based detector for an early forest fire warning system
In this paper we present a prototype of a Strip Resistive Thick GEM
photosensitive gaseous detector filled with Ne and ethylferrocene vapours at a
total pressure of 1 atm for an early forest fire detection system. Tests show
that it is one hundred times more sensitive than the best commercial
ultraviolet flame detectors and therefore, it is able to reliably detect a
flame of 1.5x1.5x1.5 m3 at a distance of about 1km. An additional and unique
feature of this detector is its imaging capability, which in combination with
other techniques, may significantly reduce false fire alarms when operating in
an automatic mode.
Preliminary results conducted with air filled photosensitive gaseous
detectors are also presented. The approach main advantages include both the
simplicity of manufacturing and affordability of construction materials such as
plastics and glues specifically reducing detector production cost. The
sensitivity of these air filled detectors at certain conditions may be as high
as those filled with Ne and EF. Long term test results of such sealed detectors
indicate a significant progress in this direction.
We believe that our detectors utilized in addition to other flame and smoke
sensors will exceptionally increase the sensitivity of forest fire detection
systems. Our future efforts will be focused on attempts to commercialize such
detectors utilizing our aforementioned findings.Comment: Presented at the International Conference on Micropattern gaseous
detectors, Crete, Greece, June 200
APPLICAZIONE DI TECNICHE DI COLLASSAMENTO IPOCENTRALE A DUE SEQUENZE SISMICHE DI BASSA ENERGIA NELLâAPPENNINO MERIDIONALE
In this study we analyse two recent low energy (Mdmax = 4.1) seismic sequences (1990-1997) that affected the northern sector (Sannio-Benevento area) of the Southern Apennines chain. We applied the Best Estimate Method to earthquake locations in order to constrain the position and geometry of the seismogenic structures. The most striking features of the obtained fault geometries indicate that earthquakes of the 1990 Benevento sequence align along a NW-SE striking structure, while the earthquakes of the 1997 Sannio sequence outline a NNE-SSW striking structure. The southernmost NW-SE structure dips towards the NE, is characterized by a conjugate fault arrangement and overlies the fault responsible for a larger historical earthquake (Iomax = XI MCS, 1688 earthquake). Available focal mechanisms from earthquakes that occurred on the recognized NW-SE and NE-SW faults are consistent with dip-slip normal solutions. This suggests the occurrence of coexisting NW-SE and NE-SW extension in the Southern Apennines
OC030: Threeâdimensional ultrasound enhances the identification of vermian fissures in the normal and abnormal cerebellum
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The current progress of the ALICE Ring Imaging Cherenkov Detector
Recently, the last two modules (out of seven) of the ALICE High Momentum
Particle Identification detector (HMPID) were assembled and tested. The full
detector, after a pre-commissioning phase, has been installed in the
experimental area, inside the ALICE solenoid, at the end of September 2006. In
this paper we review the status of the ALICE/HMPID project and we present a
summary of the series production of the CsI photo-cathodes. We describe the key
features of the production procedure which ensures high quality photo-cathodes
as well as the results of the quality assessment performed by means of a
specially developed 2D scanner system able to produce a detailed map of the CsI
photo-current over the entire photo-cathode surface.
Finally we present our recent R&D efforts toward the development of a novel
generation of imaging Cherenkov detectors with the aim to identify, in heavy
ions collisions, hadrons up to 30 GeV/c.Comment: Presented at the Imaging-2006 Conference, Stockholm, Sweden, June
200
Meeting patient expectations in migraine treatment: what are the key endpoints?
Clinical outcomes of migraine treatment are generally based on two major endpoints: acute pain resolution and effects on quality of life (QOL). Resolution of acute pain can be evaluated in a number of ways, each increasingly challenging to achieve; pain relief, pain freedom at 2 h, sustained pain-freedom, and SPF plus no adverse events (SNAE, the most challenging). QOL questionnaires help assess the burden of migraine and identify optimal treatments. Pain resolution and improved QOL form the basis of the ultimate target-meeting patient expectations, to achieve patient satisfaction. To achieve this, it is crucial to choose appropriate endpoints that reflect realistic treatment goals for individual patients. Moreover, SNAE can help discriminate between triptans, with almotriptan having the highest SNAE score. Kaplan-Meier plots are also relevant when evaluating migraine treatments. The use of symptomatic medication may lead to the paradoxical development of medication-overuse headache. In general practice, patients should use simple tools for pain measurement (e.g. headache diary) and a QOL questionnaire. A composite endpoint of pain resolution and QOL restoration would constitute a step forward in migraine management
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