The increased incidence of gastrointestinal lymphoma and adenocarcinoma in patients with celiac sprue is well recognized, with 10% to 15% developing a gastrointestinal malignancy. Somatostatinomas ...are rare neuroendocrine tumors that occur most commonly within the pancreatic head or duodenum. Although fewer than 100 cases have been reported, somatostatinomas are often associated with multiple endocrine neoplasia-1 syndrome and von Recklinghausen's disease. The unusual case of a 43-year-old woman with celiac sprue in which a somatostatinoma involving the ampulla of Vater was identified and resected is presented. To our knowledge, somatostatinomas have not been previously reported in patients with celiac sprue.
The histopathologic findings in lung tissue are reported from five cases of Philadelphia Legionnaire's Disease and the results are compared to pneumonias caused by other microbial and chemical ...agents. Histopathology of lung tissue was similar in all cases, despite the fact that death occurred between the fourth and 14th day of clinical illness. The inflammatory response was almost totally limited to the lower respiratory tract and primarily involved respiratory bronchioles, alveolar ducts and alveoli. Major bronchial branches and pulmonary interstices showed little or no involvement. There was considerable variation in the extent and nature of the consolidation, but the overall reaction pattern was highly characteristic of diffuse alveolar damage. Most involved areas showed intra-alveolar, fibrinocellular mononuclear cell predominant exudates, associated with pneumonocytic hyperplasia and slough. These findings plus the presence of erythroleucophagocytosis by macrophages and paucity of polymorphonuclear leucocytes are commonly associated with psittacine pneumonia, and much less so with classic patterns of bacterial, viral, fungal or rickettsial pneumonias. Of the toxic inhalants, nickel carbonyl, phosgene, nitrous oxide, cadmium oxide and some halogenated hydrocarbons have been associated with this tissue reaction pattern. Bacteria were notably absent in lung tissue stained by methods used to demonstrate the Legionnaires' Disease agent.
Sixty-two women had excisional breast biopsy for areas of microcalcification detected by mammography with no associated palpable mass. Carcinoma was discovered in 20 patients (32 percent). These ...cancers ranged in size from 0.6 to 14 mm in greatest diameter. Six patients had multicentric carcinoma, including one synchronous bilateral lobular carcinoma. Axillary metastasis was present in three patients (15 percent), each with multicentric lesions. Chronic cystic mastopathy (55 percent) was the most common finding associated with microcalcification. In six patients (30 percent) with carcinoma, the microcalcification was present only in adjacent tissue and ducts. Generous excisional biopsy, verification of excision of the site of microcalcification by roentgenographic examination of the specimen, and thorough histologic examination by paraffin section are mandatory to detect these early and potentially curable breast carcinomas.
Isothermal and undercooling experiments were conducted on one of the most primitive trachybasalts from Mt. Etna volcano in order to examine the crystallization mechanisms controlling the textural and ...compositional variability of clinopyroxene. Experiments were performed at 400–800 MPa, 1050–1200 °C, 0–4 wt.% H2O and at oxygen fugacity 2 log units above the Ni-NiO + 2 buffer. In isothermal experiments, the final resting temperature is approached from room temperature and clinopyroxene growth is dominated by an interface-controlled mechanism, leading to the formation of small (∼10 µm) and euhedral crystals with homogeneous compositions. Conversely, in undercooling experiments, the final resting temperature is approached after annealing at temperature above the liquidus, imposing an effective degree undercooling (ΔT) to the system. In presence of undercooling, the crystallization of clinopyroxene is dominated by a diffusion-controlled mechanism that determines the formation of large (>100 µm) crystals, constituted by two compositionally distinct domains, enriched in Al2O3 + TiO2 and SiO2 + MgO, respectively. The maximum growth rate (Gmax) decreases progressively from ∼10−7 to ∼10−8 cm/s as the degree of undercooling increases from ∼20 to ∼230 °C, due to the increase in nucleation rate. At low to moderate degrees of undercooling (ΔT = 23–41 °C) clinopyroxene is prevalently euhedral to subhedral, whereas at high degrees of undercooling, the crystal shape changes from prevalently subhedral (ΔT = 73–123 °C) to skeletal and dendritic (ΔT = 132–233 °C). Hourglass sector zoning similar to that documented for natural phenocrysts from eruptions at Mt. Etna volcano is observed only at low degrees of undercooling (ΔT = 23–32 °C). This type of zoning develops in the form of the cation exchange Si + Mg{-111} ↔ Al + Ti{100} and demonstrates that hourglass sector zoning is an effective indicator of sluggish kinetic effects caused by relatively low degrees of undercooling. In contrast, at increasing degrees of undercooling (ΔT > 32 °C), strong melt supersaturation determines the early formation of Al2O3 + TiO2-rich dendritic crystals and further SiO2 + MgO-rich overgrowths, as the bulk system attempts to return to a near-equilibrium state between the advancing crystal surface and the feeding melt.
The experimentally-determined relationship between ΔT and clinopyroxene chemistry is used to reconstruct the crystallization conditions of natural clinopyroxenes from 1974 and 2002–2003 eccentric eruptions at Mt. Etna volcano. Clinopyroxene rims record much higher degrees of undercooling (up to ∼110 °C) than crystal mantles associated with magma recharge at depth (mostly 0–40 °C). Hence, the rims track decompression-induced degassing and cooling during the ascent of magma towards the surface.
Strombolian activity is common in low-viscosity volcanism. It is characterised by quasi-periodic, short-lived explosions, which, whilst typically weak, may vary greatly in magnitude. The current ...paradigm for a strombolian volcanic eruption postulates a large gas bubble (slug) bursting explosively after ascending a conduit filled with low-viscosity magma. However, recent studies of pyroclast textures suggest the formation of a region of cooler, degassed, more-viscous magma at the top of the conduit is a common feature of strombolian eruptions. Following the hypothesis that such a rheological impedance could act as a ‘viscous plug’, which modifies and complicates gas escape processes, we conduct the first experimental investigation of this scenario. We find that: 1) the presence of a viscous plug enhances slug burst vigour; 2) experiments that include a viscous plug reproduce, and offer an explanation for, key phenomena observed in natural strombolian eruptions; 3) the presence and extent of the plug must be considered for the interpretation of infrasonic measurements of strombolian eruptions. Our scaled analogue experiments show that, as the gas slug expands on ascent, it forces the underlying low-viscosity liquid into the plug, creating a low-viscosity channel within a high-viscosity annulus. The slug's diameter and ascent rate change as it enters the channel, generating instabilities and increasing slug overpressure. When the slug reaches the surface, a more energetic burst process is observed than would be the case for a slug rising through the low-viscosity liquid alone. Fluid-dynamic instabilities cause low and high viscosity magma analogues to intermingle, and cause the burst to become pulsatory. The observed phenomena are reproduced by numerical fluid dynamic simulations at the volcanic scale, and provide a plausible explanation for pulsations, and the ejection of mingled pyroclasts, observed at Stromboli and elsewhere.
•We present laboratory experiments in which gas slugs ascend a pipe plugged with a viscous liquid.•The presence of a viscous plug enhances burst vigour.•Slug–plug interaction causes pulsatory bursting resembling natural strombolian eruptions.•Experiments indicate slug passage promotes mingling between vertically stratified magmas.
Open‐conduit conditions characterize several of the most hazardous and active volcanic systems of basaltic composition worldwide, persistently refilled by magmatic inputs. Eruptive products with ...similar bulk compositions, chemically buffered by continual mafic inputs, nevertheless exhibit heterogeneous glass compositions in response to variable magma mixing, crystallization, and differentiation processes within different parts of the plumbing system. Here, we document how multivariate statistics and magma differentiation modeling based on a large data set of glass compositions can be combined to constrain magma differentiation and plumbing system dynamics. Major and trace elements of matrix glasses erupted at Stromboli volcano (Italy) over the last 20 years provide a benchmark against which to test our integrated petrological approach. Principal component analysis, K‐means cluster analysis, and kernel density estimation reveal that trace elements define a multivariate space whose eigenvectors are more readily interpretable in terms of petrological processes than major elements, leading to improved clustering solutions. Comparison between open‐ and closed‐system differentiation models outlines that steady state magma compositions at constantly replenished and erupting magmatic systems approximate simple fractional crystallization trends, due to short magma residence times. Open‐system magma evolution is associated with magma storage crystallinities that are lower than those associated with closed‐system scenarios. Accordingly, open‐system dynamics determine the efficient crystal‐melt separation toward the top of the reservoir, where eruptible melts continuously supply the ordinary activity. Conversely, a mush‐like environment constitutes the bottom of the reservoir, where poorly evolved magmas result from mixing events between mush residual melts and primitive magmas injected from deeper crustal levels.
Plain Language Summary
Volcanoes characterized by continuous eruptive activity are typified by constant replenishment of new magma, rising from deeper regions of the crust. The volcanic glass (supercooled silicate melt), represents the residual liquid of magma crystallization, and is found as the intracrystalline matrix of eruptive products. The study of its chemical composition may provide insight into the processes occurring at depths beneath the volcanic vent, where magma compositional changes result from crystallization and mixing with new magma rising from depth. We combine statistical analyses and analytical equations based on the chemical composition of the matrix glasses from Stromboli volcano, in order to constrain the processes which produce their chemical variations, identifying different environments where magmas are stored at depth. Our results also show that when magma is stored for a short period of time, the chemical changes to which the magma is subjected in a constantly replenished system are similar to those occurring in a system which is closed to new inputs of magma.
Key Points
The combination of multivariate statistics with geochemical modeling provides new constraints on magma differentiation processes
Multivariate statistics based on trace elements allow better retrieval of petrological information than those based on major elements
Magma differentiation in open systems approximates that occurring in closed systems when magma residence timescales are short
