155 research outputs found
Diabetic fibrous mastopathy: sonographic-pathologic correlation
No full textFibrous and inflammatory lesions of the breast in patients with early-onset, longstanding insulin-dependent diabetes mellitus (IDDM) can lead to misdiagnosis because the clinical, mammographic, and sonographic findings simulate breast cancer. We report a case of diabetic fibrous mastopathy with suspicious clinical, imaging, and cytologic findings. 2004 Wiley Periodicals, Inc
Raman spectroscopic analysis of minerals of the arsenbrackebuschite group
No full textThe arsenbrackebuschite group belongs to the brackebuschite supergroup of minerals that currently has about twenty members. These minerals are monoclinic with space group P21/m, and they have general formula A2M3+(TO4)2(OH) with A = Pb, Ba, Sr, Ca, M = Al, Fe3+, Mn3+, Zn, Cu, T = V, As, P, S. Members of the arsenbrackebuschite group are characterized by the presence of As in the tetrahedral sites. This group includes aldomarinoite [Sr2Mn3+(AsO4)2(OH)], arsenbrackebuschite [Pb2Fe3+(AsO4)2(OH,H2O)], canosioite [Ba2Fe3+(AsO4)2(OH)], feinglosite [Pb2Zn(AsO4)2(OH,H2O)], grandaite Sr2Al(AsO4)2(OH)] and lombardoite [Ba2Mn3+(AsO4)2(OH)]. A crystal chemical study has been conducted on minerals of this group collected in Valletta mine, a small Fe-Mn deposit located in Valletta Valley (Canosio municipality, Maira valley, Piedmont, Italy). Raman spectroscopy analyses show that chemical composition variations produce a variation in the spectra peak intensity and some shifts of the peaks that allow distinguishing between the Ba-rich and Sr-rich end members and the V-rich crystals. Raman spectra are characterised by two main peaks in the region of 750-950 cm-1 that can be assigned to the stretching modes of (AsO4)3- (810-880 cm-1) and (VO4)3- (780-875 cm-1) groups. We have observed a clear relation between Sr/Ba content and the position of these peaks that allows, at first, to distinguish Sr-rich from Ba-rich samples and that could be used to calibrate the Ba-Sr content. In fact, intermediate compositions show also intermediate values for some of the most important peaks. A broad peak is always observed in the 2500-4000 cm-1 region, due to the stretching modes of the O-H bonds
Language disturbances associated to insular and entorhinal damage: study of a patient affected by herpetic encephalitis
No full textThe herpes simplex encephalitis (HSE) patient reported in this study presented a left hemisphere lesion limited to the left insula and to the left anterior parahippocampal region. The patient was followed longitudinally, focusing on the aphasia type, the language recovery, and the integrity of semantic representations. The language deficit was of fluent type, without phonological impairment, and showed a good but incomplete recovery after four months. A semantic impairment was possible at the onset, but recovered quickly and did not present a disproportionate impairment of living categories
Crystal-chemistry and polytypism in lombardoite, Ba2Mn(AsO4)2(OH)
No full textThe brackebuschite supergroup of minerals currently has about twenty members. The minerals are monoclinic with space group P21/m (7.5577(4) < a < 7.87636(18) Å; 5.97761(15) < b < 6.1130(6) Å; 8.7316(6) < c < 9.1678(2) Å; 111.785(6) < β < 112.930(3)°) and have general formula A2M3+(TO4)2(OH) with A = Pb, Ba, Sr, Ca, M = Al, Fe3+, Mn3+, Zn, Cu, T = V, As, P, S. Among these, the arsenbrackebuschite group include minerals having As dominant at the tetrahedral sites. Lombardoite [Ba2Mn3+(AsO4)2(OH)] is thus a member of this group, described for the first time at Valletta mine, a small Fe-Mn deposit located in Valletta Valley (Canosio municipality, Maira valley, Piedmont, Italy). A crystal chemical study conducted by single crystal X-ray diffraction on Sr-rich lombardoite crystals from this locality have shown the main partitioning scheme of elements among the sites and the structural responses in terms of bond length and polyhedra geometry. Raman spectroscopy analyses on the same crystals show that chemical composition variations produce a shift of the spectra peaks wavenumber that allows distinguishing between the Ba-rich and Sr-rich members and the V-rich crystals of the solid solution. A clear relation between Sr/Ba content in lombardoite and the position of these peaks is found that allows, at first, to distinguish Sr-rich from Ba-rich samples and that could be used to calibrate the Ba-Sr content.
The diffraction studies also revealed a new polytype, having space group C2/m and a cell parameter four times the unit base (27.832(2) < a < 28.1443(3) Å; 6.11680(10) < b < 6.1476(4) Å; 9.3705(4) < c < 9.4391(5) Å; 99.928(3) < β < 100.229(6)°; polytype 4M), having a along [101] of the brackebuschite cell (polytype 1M). The frequent presence of streaking in the reciprocal space along the a* direction in many of these crystals showed that this polytype must be intergrown with the polytype 1M. In fact, both structures can be described as a different stacking of the same structural unit shifted of 1⁄2 c (brackebuschite cell). All lombardoite crystals showing the -4M polytype have significant Sr amount, whereas we have observed limited solid solution of Sr in lombardoite-1M and of Ba in its Sr-counterpart, aldomarinoite [Sr2Mn3+(AsO4)2(OH)]. Interestingly, the cationic order of Sr in the A1 sites of the brackebuschite structure leads to a volume reduction of these polyhedra, whereas the cationic ordering of Ba in the larger A2 sites accommodates the chemical strain. This helps to reduce the strain and apparently stabilizes the polytype 4M. The Raman signal is not sensitive to the order of the layers within the analyzed volume, making the distinction of the polytypes intergrowths with similar composition unfeasible. Observations through Transmission Electron Microscopy, have been done with the aim of characterize the micro-syntactic (crystallographically oriented) intergrowths of both polytypes
Dinamica delle calotte glaciali: una revisione critica della SIA (shallow-ice approximation)
No full textInterpretation of numerical transport tests with single and dual porous medium approaches
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Single and dual domain models to evaluate the effects of preferential flow paths in alluvial porous sediments
No full textTypical features of preferential flow paths were evidenced by numerical tests of convective transport of conservative solutes performed in three blocks of alluvial sediments at the scale of depositional elements. The numerical experiments are analysed with standard single-domain models (SDMs) and with dual-domain models (DDMs): the model parameters are identified by minimisation of the misfit between the "experimental" and the modelled cumulative breakthrough curves (BTCs) and between the "experimental" and the modelled temporal moments of the BTCs. The results for the SDMs show different behaviours for the three model blocks and for the different flow directions, in good agreement with their hydrostratigraphic characteristics. The results for the DDMs sometimes correspond to cases for which one of the two domains is dominant and its values of diffusivity and average velocity are close to those obtained for the SDM; in some cases the DDM performs much better than the SDM and correctly represents the effects of preferential flow paths. Finally the relevance of the DDM is analysed in the framework of multi-objective optimisation: a proper choice of the objective-functions yields Pareto sets whose geometries are different for single- and dual-domain media
Single- and Dual-domain Models of Solute Transport in Alluvial Sediments: the Effects of Heterogeneity Structure and Spatial Scale
No full textFine-scale heterogeneity of alluvial aquifers controls solute transport in groundwater at the scales relevant for practical applications: the architecture of sedimentary structures might create preferential flow paths (PFPs) or hydraulic barriers, which affect the breakthrough curves (BTCs). Objective of this paper was the assessment of the relevance of single- and dual-domain models for different heterogeneity patterns and scale lengths in alluvial sediments. Three case studies have been analysed with a classical single-domain model (SDM) and with three dual-domain models (DDMs): a dual-porosity model (DPorM) and two dual-permeability models (DPerM), which differ for the presence or the absence of solute exchange between the two domains. The first case study includes numerical tracer tests in metre-scale blocks of alluvial sediments; the second is a laboratory experiment of tracer injection in a decimetre-scale column of homogeneous sand; the third is a field tracer test performed at hectometre scale at the Cape Cod site. The relevance of the solute exchange in the DDMs is analysed with the characteristic advection and exchange times and with the Péclet and Damköhler numbers. The SDM is satisfactory for alluvial sediments with unstructured heterogeneity. The uncoupled DPerM is shown to be a better approach than the DPorM in sediments with PFPs; in this case, the coupled DPerM does not improve significantly the results of the uncoupled DPerM. A minor difference between the results of the three DDMs is observed for sediments in which the non-Fickian behaviour is not clearly determined by the presence of PFPs
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