Patrizia Landi

Bio: Patrizia Landi is an academic researcher from National Institute of Geophysics and Volcanology. The author has contributed to research in topics: Magma & Lava. The author has an hindex of 27, co-authored 80 publications receiving 2779 citations. Previous affiliations of Patrizia Landi include University of Pisa.

Onset of the persistent activity at Stromboli Volcano (Italy)

Abstract: Stromboli, known worldwide as the "Lighthouse of the Mediterranean", is commonly believed to have been in a state of persistent activity for the past 2000–2500 years However, historical sources older than 1000 AD are not accurate enough to assess if the activity of the volcano was exactly the same as we see at present In order to attempt to identify the onset of the present eruptive regime, and assess if it has been maintained with the same characteristics through time, stratigraphic and radiometric studies of the recent tephra deposits were undertaken Up to 4-m-deep stratigraphic trenches, dug at a height of approximately 500 m on the NE flank of the volcano, exposed a conformable tephra pile containing charcoal fragments One of the most interesting finds was the discovery of a 7-cm-thick weathered bed rich in organic matter (thin palaeosol) approximately 3 m below the surface The sequence underneath the palaeosol consists of decimetre-thick lapilli fallout beds alternating with ash deposits bearing small charcoals with calibrated ages of between the fourth century BC and the first century AD The sequence above the palaeosol is charcoal free and consists of coarse-ash deposits with discrete, centimetre-thick lapilli fallout beds composed of crystal-poor golden pumice and subordinate crystal-rich black scoriae similar to scoria/pumice pairs emitted during the more energetic explosions of the present-day activity The data collected indicate that between the third and seventh centuries AD, after a period of quiescence, the activity resumed with an eruptive style identical to the present one We conclude that the "Lighthouse of the Mediterranean" actually began its activity in a period much later than previously thought

Stromboli volcano (Aeolian Archipelago, Italy): An open window on the deep-feeding system of a steady state basaltic volcano

Abstract: [1] Paroxysms at Stromboli are the most violent manifestations of the persistent activity and are related to the emission of small volumes (103–105 m3) of nearly aphyric HK-basaltic pumices. They offer the exceptional opportunity to detail the mixing-crystallization-degassing processes that occur in a steady state basaltic arc volcano. We present mineralogy, major, volatile, and trace element geochemistry of olivine-hosted melt inclusions of these pumices. In all the paroxysms, melt inclusions hosted in olivines Fo88–91 have recorded the parental melts rich in CaO (up to 14.5 wt %) but low in FeO (6–7 wt %). They demonstrate recurrent variations in the K2O content (1.6–1.3 wt %) and S/Cl ratios (1.2–0.8) of the melts that entered the deep system. Dynamic magma mixing between melts slightly distinct by their degree of evolution, rapid crystallization, and entrapment of gas-oversaturated melts during decompression are indicated by (1) the high density of irregular, clear melt inclusions, and embayments in homogeneous olivines (Fo87±0.5–Fo83±0.5), (2) the variable ratio between melt and gas bubble, and (3) the variability of melt inclusion compositions in both major (CaO/Al2O3 = 1–0.59) and volatile (3.4–1.8 wt % H2O, 1582–1017 ppm CO2) elements. FeO-rich melt inclusions in patchy, reversely zoned olivines also demonstrate interactions between ascending melt blobs and inherited olivine crystals. We propose a model involving a vertically extended dike-like system, where magmas progress and differentiate. On the basis of olivine growth rate calculations the volatile-rich magma blobs may ascend within few hours to few tenths of hours. Finally, we propose that sulfur degassing is possibly initiated during the early stage of magma differentiation.

Dynamics of magma mixing and degassing recorded in plagioclase at Stromboli (Aeolian Archipelago, Italy)

Abstract: Crystal-rich materials (scoriae and lava flows) emitted during the 1985–2000 activity of Stromboli were taken into consideration for systematic study of bulk rock/matrix glass chemistry and in particular for the study of chemical and textural zoning of plagioclase, the most abundant mineral phase. Over the considered time period, bulk rock composition remained fairly constant in both major (SiO2 49.2–50.9 wt% and K2O 1.96–2.18 wt%) and trace elements. The quite constant chemistry of matrix glasses also indicates that the degree of crystallization of magma was maintained at around 50 vol%. Plagioclase ranges in composition between An62 and An88 and is characterized by alternating, <10–100 μm thick, bytownitic and labradoritic concentric layers, although the dominant and representative plagioclase of scoriae is An68. The labradoritic layers (An62–70) show small-scale (1–5 µm), oscillatory zoning, are free of inclusions, and appear to record episodes of slow crystal growth in equilibrium with a degassed liquid having the composition of the matrix glass. In contrast the bytownitic layers (An70-An88) are patchy zoned, show sieve structure with abundant micrometric glass inclusions and voids, and are attributed to rapid crystal growth.

Image Processing

Abstract: MUCKE aims to mine a large volume of images, to structure them conceptually and to use this conceptual structuring in order to improve large-scale image retrieval. The last decade witnessed important progress concerning low-level image representations. However, there are a number problems which need to be solved in order to unleash the full potential of image mining in applications. The central problem with low-level representations is the mismatch between them and the human interpretation of image content. This problem can be instantiated, for instance, by the incapability of existing descriptors to capture spatial relationships between the concepts represented or by their incapability to convey an explanation of why two images are similar in a content-based image retrieval framework. We start by assessing existing local descriptors for image classification and by proposing to use co-occurrence matrices to better capture spatial relationships in images. The main focus in MUCKE is on cleaning large scale Web image corpora and on proposing image representations which are closer to the human interpretation of images. Consequently, we introduce methods which tackle these two problems and compare results to state of the art methods. Note: some aspects of this deliverable are withheld at this time as they are pending review. Please contact the authors for a preview.

人唾液天疱疮抗原的纯化

Abstract: 1. Place animal in induction chamber and anesthetize the mouse and ensure sedation. 2. Once the animal is sedated, move it to a nose cone for hair removal using cream. Only apply cream to the area of the chest that will be utilized for imaging. Once the hair is removed, wipe area with wet gauze to ensure all hair is removed. 3. Move the animal to the imaging platform and tape its paws to the ECG lead plates and insert rectal probe. Body temperature should be maintained at 36-37°C. During imaging, reduce anesthesia to maintain proper heart rate. If the animal shows signs of being awake, use a higher concentration of anesthetic.

An Introduction To The Theory Of Point Processes

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Volatiles in subduction zone magmas : concentration and fluxes based on melt inclusion and volcanic gas data

Abstract: Abstract Owing to advances in microanalytical techniques over the last 15 years, there is a growing database on the volatile contents of subduction-related magmas as recorded in melt (glass) inclusions trapped in phenocrysts in volcanic rocks. Basaltic magmas from subduction zones show a wide range of water contents, ranging from as high as 6–8 to 3000 ppm, suggesting that no melt inclusions sample undegassed arc magmas. The Cl and S contents of arc basaltic magmas are greater than midocean ridge basalts, indicating that these volatiles are also recycled from subducted sediment and altered oceanic crust back into the mantle wedge. Comparison of the fluxes of volatiles subducted back into the mantle along subduction zones and returned from the mantle to the surface reservoir (crust, ocean, and atmosphere) via magmatism suggests that there is an approximate balance for structurally bound H2O and Cl. In contrast, ∼50% of subducted C appears to be returned to the deep mantle by subduction, but uncertainties are relatively large. For S, the amount returned to the surface reservoir by subduction zone magmatism is only ∼15–30% of the total amount being subducted. Dacitic and rhyolitic magmas in arcs contain 1–6 wt.% H2O, a range that overlaps considerably with the values for basaltic magmas. Either basaltic parents for these differentiated magmas are relatively H2O-poor, or intermediate to silicic arc magmas form through open-system processes involving variable amounts of crustal melting, mixing with basalt and basaltic differentiates, and fluxing of CO2-rich vapor from mafic magma recharged into silicic magma bodies. Consideration of H2O–CO2 relations and gaseous SO2 emissions for intermediate to silicic arc magmas shows that such magmas are typically vapor-saturated during crystallization in the middle to upper crust. Gas emissions thus reflect migration and accumulation of volatiles within complex open magmatic systems.

Long-period volcano seismicity: its source and use in eruption forecasting

Abstract: At an active volcano, long-period seismicity (with typical periods in the range 02–2 s) reflects pressure fluctuations resulting from unsteady mass transport in the sub-surface plumbing system, and hence provides a glimpse of the internal dynamics of the volcanic edifice When this activity occurs at shallow depths, it may signal the pressure-induced disruption of the steam-dominated region of the volcano, and can accordingly be a useful indicator of impending eruption