651 research outputs found
Unusual, rapidly growing ulcerative genital mass due to herpes simplex virus in a human immunodeficiency virus-infected woman.
No full textUnusual, rapidly growing ulcerative genital mass due to herpes simplex virus in a human immunodeficiency virus-infected woman
Structural features of the 2007 Stromboli eruption
No full textOn 27 February 2007, two NE–SW and NNW–SSE dike-fed effusive vents opened to the North (at 650 and
400 m above sea level, asl) of the summit craters at Stromboli, forming a fissure parallel to the inner walls of
the Sciara del Fuoco (SdF) sector collapse depression. The formation of these vents was soon followed by
rapid subsidence of the summit crater area. This partly obstructed the central conduit, temporarily choking
the fissure and increasing the deformation of the upper part of SdF. The reactivation of the NNW–SSE vent
and the opening of a new vent located at 500 m asl, fed by a second dike, released the internal pressure and
surface deformation ceased. The eruption then continued again from the 400 m vent, after a summit
explosion on 15 March, until ending in early April after a progressive decrease of magma output. Repeated
NE–SW dike intrusions have occurred in recent years, close to the upper SE limit of the SdF. In that zone,
named Bastimento, the eruptive fractures traced the discontinuities that borders the SdF, increasing the risk
of triggering new sector collapse. Whereas the NE–SW trending structures lie along the regional volcanostructural
trend of the Aeolian arc through Stromboli, the NNW–SSE vents are oblique to this trend and may
be controlled by the anomalous stress field within the unstable flank of the SdF. Another fundamental aspect
of the 2007 eruption is the collapse of the central conduit, due to the rapid and deep magma drainage linked
to the opening of the 400 m vent. The intrusion of dikes and development of flank vents during the 2007
eruption could possibly have triggered catastrophic landslides and related tsunami or eruptive paroxysms,
but the opening of new effusive vents released the internal pressures, diminishing the hazard.Work funded by INGV and Dipartimento Protezione Civile, Italy.Published137-1441.5. TTC - Sorveglianza dell'attività eruttiva dei vulcani3.2. Tettonica attiva3.5. Geologia e storia dei vulcani ed evoluzione dei magmi3.6. Fisica del vulcanismo4.3. TTC - Scenari di pericolosità vulcanicaJCR Journalreserve
Thermo-barometric constraints on the Mt. Etna 2015 eruptive event
No full textThe petrologic and thermobarometric study of volcanic products frequently emitted
during short strombolian to lava fountaining events from the Mt. Etna Summit Craters
allow us to constraint the T-P-XH 2 O phase stability, crystallization conditions and
mixing processes along the main open-conduit feeding system. In this study, we
discuss new petrologic, thermo-barometric data and related Rhyolite-MELTS modelling
for the December 2015 eruptive activity that involved the concomitant activation of all
Mt. Etna summit craters. The obtained results, in comparison with the previous
paroxystic events of the 2011-2012, reinforce the model of a vertically extended
feeding system and highlight that the activity at the New South East Crater was fed by
a magma residing at significant shallower depth with respect to Central Craters (CC)
and North East Crater (NEC), even if all conduits are fed by a common deep (P = 530-
440 MPa) basic magmatic refilling. Plagioclase stability model and recognized
dissolution and resorption textures confirm its dependence on H 2 O content, thus
suggesting that further studies on the effect that flushing from fluids with different H 2
O/CO 2 ratio are needed in order to understand the eruption triggering mechanisms of
paroxystic fountaining
Unraveling the solidification path of a pahoehoe "cicirara" lava from Mount Etna volcano
No full textThe solidified surface of a lava flow reflects the viscosity of its molten fraction and the crystal content during flow; crystal-poor basaltic lavas produce pahoehoe fields, whereas crystal-rich ones solidify with aa carapaces. At Mount Etna volcano aa morphologies are very common, in turn, pahoehoe lavas are rare. The latter are locally named “cicirara” due to the presence of cm-sized plagioclase phenocrysts much more abundant than in aa lavas. The phenocryst content of “cicirara” lavas contrasts with the low viscosity generally associated with pahoehoe morphology. Therefore, to reconcile the discrepancy between textural and volcanic observations, we have studied the most primitive pahoehoe “cicirara” lava sampled until now. Two samples at 0.5 and 1 m from the bottom of the two-meter thick lava flow were investigated on the basis of their mineral compositional variations and textural features, i.e. size frequency and crystal size distribution (CSD). Results coupled with rheological models indicate that only large phenocrysts of plagioclase (>1 mm) and clinopyroxene have grown before eruption. Thermobarometric models and petrological computations based on the composition of plagioclase and clinopyroxene phenocryst cores highlight that only a small amount (10-15 vol.%) of crystals equilibrated at 12 km of depth. Cumulative size frequency and CSD data also indicate that plagioclase and clinopyroxene phenocryst rims grew heterogeneously and coalesced around their cores at depths <1 km, before eruption. In this view, the “cicirara” lava was erupted with a low crystalline content that favoured the formation of its pahoehoe surface; however, crystals with a size <1 mm (~75 vol.%) solidified at post-eruptive conditions.
Our findings underline that the emplacement of high-viscosity aa or low-viscosity pahoehoe lavas is driven by the degree of undercooling imposed by the volatile exsolution rate in the shallowest portion of the Etnean plumbing system. A slow magma ascent rate promotes significant intratelluric degassing and widespread nucleation; consequently, the viscosity of the suspension significantly increases leading to an aa morphology. In contrast, pahoehoe “cicirara” lavas are associated with a rapid rise to the surface of poorly degassed, undercooled magmas
Mediastinite tubercolare complicata da fistola mediastino-esofagea in AIDS:un caso clinico
No full textMediastinite tubercolare complicata da fistola mediastino-esofagea in AIDS:un caso clinic
Bacteriological and clinical efficacy of various antibiotics used in the treatment of streptococcal pharyngithis in Italy : an epidemiological study
No full textA total of 123 community paediatricians and 23 microbiology laboratories studied the clinical and bacteriological efficacy of treatment of group A streptococcal pharyngitis in Italy. Of 1065 patients, from whom Streptococcus pyogenes was isolated, 723 returned to follow up and of these 138 (19%) still had a positive throat culture. The erythromycin resistance (ER) rate was 23.7% with resistance phenotype distribution of: 31.7% constitutive (CR), 26.6% inducible (IR) and 41.7% efflux pump (M) resistance phenotype. All strains were susceptible to the beta-lactam agents tested. CR strains were highly resistant to all 14, 15 and 16 membered macrolides with the exception of rokitamycin which showed activity against 37.8% of isolates. All phenotype M and some IR isolates were susceptible to clindamycin, rokitamycin, josamycin and spiramycin; clarithromycin was active against a small percentage of strains belonging to the IR and M phenotype. Bacterial eradication was found in 85.5, 78.7 and 75.8% of the penicillin, macrolide and cephalosporin treated groups. Genotyping of strains showed that 8.7% of the 19% of cases classified as 'failed bacterial eradication' were due to recolonization with a different isolate, observed exclusively among beta-lactams treated patients. Clinical cure was achieved in a high percentage of cases, irrespective of the antibiotic prescribed, with the best clinical efficacy being found following therapy with amoxycillin and clarithromycin (90.9%)
Distribution-aware estimation of the minimum achievable uncertainty in diffusion-tensor imaging (DTI)
No full textDiffusion tensor imaging (DTI) provides exquisite sensitivity to structural and microstructural characteristics of brain tissue, and is routinely employed in advanced neu-roimaging applications. DTI is commonly performed using intrinsically noisy echo-planar imaging techniques and poses high demands both on scanner performance and on in-scanner subject time, which in turn is directly related to the number of diffusion-weighting direction one requires. While DTI-derived indices such as fractional anisotropy (FA), diffusion tensor trace and anisotropy mode have proven extremely useful in characterizing disease-related aberrations, their estimation is commonly performed using fitting routines that do not properly take into account MRI noise distribution. In this paper, we present a distribution-aware maximum likelihood tensor estimation framework which also allows, for the first time, separate local noise estimation in both diffusion weighted and reference images. We validate our framework using multiple water phantom diffusion weighted acquisitions, and demonstrate its feasibility in human data. We then employ our framework within Monte Carlo simulations to show how the minimum achievable uncertainty attainable in DTI depends on signal-to-noise ratio (SNR) and number of diffusion gradient directions, demonstrating that these dependencies could be recast into simple power laws which may serve as guidelines for application-specific DTI protocol design
Mycobacterium chimaera infections following cardiac surgery in Italy: results from a National Survey Endorsed by the Italian Society of Cardiac Surgery
No full textAIMS: A global outbreak of Mycobacterium chimaera infections following cardiac surgery and linked to contaminated heater-cooler units (HCUs) is currently ongoing. Neither the status of this outbreak in Italy nor the mitigation strategies adopted by adult cardiac surgery units (ACSUs) are currently known. In 2017, the Italian Society of Cardiac Surgery launched a national survey among the Italian ACSU to shed some light on this issue.METHODS: In Italy, there are 90 ACSUs across 20 regions. From May to November 2017, these ACSUs were surveyed collecting data on patients diagnosed with MC infections, ACSU workload, HCU models in use and control measures adopted in the operatory room.RESULTS: The response rate was 87.8%. The median number of cardiac procedures at each ACSU was 450/year [interquartile range (IQR) 350-650 procedures/year], and nationally, the number of procedures/year exceeded 40k. In Italy, seven patients with M. chimaera infections following cardiac procedures have been reported since 2015: all had aortic or valvular surgery as the first procedure; the median latency between the first operation and the infection was 2 years (IQR 2-3.25). Mortality for patients requiring redo cardiac surgery was 50%. M. chimaera infections risk was 0.4-1 patient every 1000 cardiac procedures. The most common HCU model in Italy is the 3T HCU (70.9%). The most common control measures adopted included implementing new HCU disinfection protocols, using sterile or filtrated water in the HCU and displacing HCU fans away from the patient: HCU replacement and microbiology testing were instead infrequent.CONCLUSION: In Italy, the risk of contracting M. chimaera infections and the mortality reported are in line with other European countries, but significant heterogeneity exists on the mitigation strategies adopted to prevent further M. chimaera inoculations, suggesting the development of national guidelines
Da Reggio Emilia al mondo: lo sguardo di Franco Cigarini nel sostegno alle lotte di liberazione delle colonie portoghesi
No full textThermo-barometric constraints on Mt. Etna feeding system during the 2015 summit eruptive activity
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