117,325 research outputs found
Vivere nell’arte molte vite: la didattica della letteratura nella scuola secondaria
No full textL'intervento tratta sinteticamente il ruolo del docente di italiano nella scuola secondaria e le strategie d'uso delle opere letterarie
Tectonic control on vein attributes and deformation intensity in fault damage zones affecting Natih platform carbonates, Jabal Qusaybah, North Oman
No full textUnderstanding the factors that control fracture patterns in fault damage zones is fundamental to predicting fault zone permeability in the subsurface. In this contribution, we present outcrop data on vein attributes collected from 26 fault zones (10 strike-slip and 16 normal dip-slip) that cut Cretaceous Natih Formation platform carbonates exposed in the Jabal Qusaybah anticline, North Oman. Faulting occurred during the growth of the salt-cored anticline and progressed initially from dominant strike-slip faults (burial depth ∼3–4 km) to late normal dip-slip faults (burial depth <1–2 km). The displacements accommodated by both kinematic fault types range similarly from 0.1 to 100 m, and damage-zone width increases with displacement at the same rate for both types. Vein aperture (A), height (H), and spacing (S) were measured in vertical cross-sections (n = 10839 data) along fault-perpendicular, linear scanlines across fault damage zones. Data analyses indicate that, as the master slip surface is approached in each fault zone: (1) vein aperture and height generally increase; (2) vein spacing systematically decreases; and (3) deformation intensity, calculated as vein H/S ratio, increases. However, median H/S values calculated in each damage zone do not show a robust correlation with fault displacement. When analyzed collectively across-fault distributions, H/S ratios indicate that deformation intensity (i) in normal dip-slip fault damage zones is greater than in strike-slip fault damage zones; (ii) in strike-slip fault damage zones is symmetrical with respect to the master slip surface; and (iii) is locally asymmetrically distributed with greater deformation intensity in footwall blocks for normal dip-slip faults. Greater deformation in normal dip-slip fault zones is expressed by greater vein height, rather than smaller vein spacing. The main conclusion is that deformation intensity and vein attributes in fault damage zones are primarily controlled by burial stress and fault kinematics, and less importantly by rheological contrasts between layers, rather than local stress induced by fault displacement
Evidences of late Miocene low-angle extensional tectonics affecting the western Northern Apennines orogenic wedge.
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Fluid pressure cycles, variations in permeability, and weakening mechanisms along low-angle normal faults: the Tellaro detachment, Italy
No full textClassical frictional fault reactivation models indicate that slip along misoriented fault planes is not possible under most conditions. Nevertheless, active or exhumed low-angle normal faults have been described in many settings worldwide. This discrepancy is addressed by contrasting models: (1) those proposing that low-angle normal faults result from postkinematic passive rotation of former high-angle extensional faults; and (2) those proposing that specific conditions can promote slip along misoriented fault planes. This paper describes the Tellaro detachment, a mid–late Miocene low-angle normal fault that was responsible for ∼500 m of tectonic vertical thinning in the carbonate-dominated Triassic to Lower Miocene succession of the Northern Apennines, Italy. By integrating structural, petrographic, isotopic, and fluid inclusion data, we show that: (1) the main kinematic activity of the Tellaro detachment occurred between ∼8 and 4 km depths and peak temperature ∼190 °C; (2) dilational breccias, tens of cubic meters in volume, are frequently associated with major low-angle fault segments; (3) slip along misoriented planes was favored by elevated fluid pressures and low differential stress; and (4) the fault system was characterized by transient permeability pulses and overpressure buildups, associated with multiple fracturing and cementation events that caused the downward migration of master slip surfaces.
Results presented in this study show that: (1) in a fluid-active regime, continental crustal thinning can occur for shallow values of fault dip; (2) low-angle normal faults have a great influence on fluid circulation within the upper crust; and (3) episodic permeability enhancement and destruction in detachment faults can promote overpressure buildups, triggering deformation episodes
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Sedimentary facies control on fracture and mechanical stratigraphy in siliciclastics: Marnoso-arenacea formation, Northern Apennines, Italy
No full textJointing in bedded siliciclastic sedimentary successions has been mainly analyzed in terms of fractured layers thickness-normalized joint spacing and related probability distributions, commonly neglecting the influence of primary structures on the petrophysical properties, joint height patterns, spatial arrangements and best-fitted spacing distributions. Taking into account the depositional controls on mechanical and fracture stratigraphy is crucial for improving the predictive potential of geological modelling in exploration and exploitation of un- derground resources, gas injection and storage. Here, we present a high-resolution, structural-stratigraphic study carried out on a 72 m-thick succession of the Marnoso-arenacea foredeep turbidites, exposed in the Northern Apennines of Italy. The systematic integration of the structural and sedimentological characterization of this basin-plain turbiditic succession, coupled with petrophysical and geomechanical measurements, represents the fracture and mechanical stratigraphy database onto which we tested the standardly used fracture density pa- rameters and the best-fitted probability distributions, i.e. normal, log-normal, gamma and exponential, applied to fracture spacing analysis. Our results document that cumulative analysis does not identify the variability of joint height patterns and spacing distributions in siliciclastic turbidites, which instead requires considering single sedimentary facies types. Specifically, sandstones are affected by facies bounded joints and gamma spacing distributions while clay-rich and poorly sorted facies show a higher abundance of top bounded and throughgoing joints, and are best fitted by log-normal spacing distributions. We suggest that the fracture and mechanical stratigraphy should be studied at the facies scale resolution to unravel the strong control of the sedimentary facies for improving the characterization of siliciclastic reservoirs
Glycyrrhizin and mannitol nasal therapy: cytological and clinical outcomes in chronic rhinitis
No full textIntroduction Chronic rhinitis (CR) represents a widespread inflammation with a high incidence in the general population. Although it is generally considered a benign condition, CR has a relevant impact on quality of life and requires a specific treatment approach.Objective The aim of the present study was to investigate the efficacy of glycyrrhizin and mannitol intranasal treatment on chronic rhinitis using cytological analysis and subjective evaluation of symptoms.Methods A total of 55 patients suffering from chronic rhinitis were enrolled in the present study, 34 with allergic rhinitis (AR) and 21 with nonallergic rhinitis (NAR). The severity of four different nasal symptoms was determined by using a visual analogue scale (VAS). Specimens obtained by nasal scraping were collected for cytological analysis. Data were acquired before and after a 30-day treatment with glycyrrhizin and mannitol nasal spray. Statistical analyses were performed.Results The VAS scores for all four nasal symptoms considered in the present study, as well as for neutrophil cells, reduced significantly after therapy in both allergic and nonallergic patients. The number of eosinophils was not significantly lower in nonallergic patients.Conclusion A 30-day topical treatment with glycyrrhizin and mannitol may improve nasal symptoms and reduce inflammatory cells in the nasal mucosa in patients with chronic rhinitis without significant contraindications. Further studies could support our results and would better clarify all the aspects of this treatment
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