196,294 research outputs found
XML Updates
No full textThe term XML Updates refers to the act of modifying XML data while preserving its identity, through the operators provided by an XML manipulation language. Identity preservation is crucial to this definition: the production of XML data from XML data without preserving the original data identity is called XML transformation. The general notion of identity has many concrete incarnations. The XQuery/XPath data model (see [2]) associates a Node Identity to each node of the XML syntax tree. In a language based on this data model, updates differ from transformations because the former modify the data but preserve node identities. Another hallmark of updates is that an expression that refers to the data being updated may have a different value after the update is evaluated, while the evaluation of XML transformations does not change the value of any other expression
[Recensione a] P. Levi, Il carteggio con Heinz Riedt, a cura di M. Mengoni, Torino, Einaudi, 2025
No full textPalynology and isotope geochronology of the Upper Ordovician-Silurian successions (Ghelli and Soltan Maidan Formations) in the Khoshyeilagh area, eastern Alborz Range, northern Iran; stratigraphic and palaeogeographic implications
No full textSurface samples from the Ghelli and Soltan Maidan Formations in the Khoshyeilagh area of the eastern Alborz Range, northern Iran, were analyzed to determine the age and the stratigraphic relationship of these two units. The samples contained rich palynomorph assemblages, dominated by acritarchs (36 species recognized, distributed among 28 genera) and chitinozoans (nine species identified, distributed among seven genera). Cryptospores and scolecodonts as well as a few graptolite remains were also observed, although not studied in detail. Based on the restricted stratigraphic range of chitinozoan and acritarch species, a Late Ordovician (late Katian-Hirnantian) age is assigned to the Ghelli Formation. Palynological samples from the Soltan Maidan Formation yielded acritarch assemblages characterized by species commonly found in Upper Ordovician sediments together with typical middle Silurian forms. Considering reworking of the Upper Ordovician species, the age of the investigated part of the Soltan Maidan Formation is not younger than Gorstian (early Ludlow, early late Silurian). U-Pb zircon ages of 434.4 +/- 6.4 Ma (Telychian, late Llandovery, late early Silurian) obtained for granitic clasts collected at the base of the Soltan Maidan Formation, are consistent with the inferred palynological age and indicate that granite emplacement, cooling, exhumation, erosion, transportation and deposition of its clasts took place in a time interval estimated to be 5 to 10 million year long. Based on the presence of diagnostic chitinozoan taxa, the Ghelli Formation can be assigned to the Armoricochitina nigerica, Ancyrochitina merga, and Spinachitina oulebsiri chitinozoan biozones. Chitinozoan assemblages reflect a clear palaeobiogeographic affinity with the previously defined 'North Gondwana Domain'. The composition of acritarch assemblages also appears to be consistent with newly proposed hypotheses of a Late Ordovician phytoplanktonic biogeographical differentiation between a Laurentian/Baltica realm, and a Gondwanan realm to which the present assemblages belong. The presence of cryptospores together with taxonomically diverse chitinozoan, acritarch, and scolecodont assemblages, suggest a relatively shallow marine, platformal depositional environment for the Ghelli Formation. (C) 2011 Elsevier B.V. All rights reserved
Organization of the respiratory supercomplexes in cells with defective complex III: Structural features and metabolic consequences
Get PDFThe mitochondrial respiratory chain encompasses four oligomeric enzymatic complexes (complex I, II, III and IV) which, together with the redox carrier ubiquinone and cytochrome c, catalyze electron transport coupled to proton extrusion from the inner membrane. The protonmotive force is utilized by complex V for ATP synthesis in the process of oxidative phosphorylation. Respiratory complexes are known to coexist in the membrane as single functional entities and as supramolecular aggregates or supercomplexes (SCs). Understanding the assembly features of SCs has relevant biomedical implications because defects in a single protein can derange the overall SC organization and compromise the energetic function, causing severe mitochondrial disorders. Here we describe in detail the main types of SCs, all characterized by the presence of complex III. We show that the genetic alterations that hinder the assembly of Complex III, not just the activity, cause a rearrangement of the architecture of the SC that can help to preserve a minimal energetic function. Finally, the major metabolic disturbances associated with severe SCs perturbation due to defective complex III are discussed along with interventions that may circumvent these deficiencies
The Background of Mitochondrial DNA Haplogroup J Increases the Sensitivity of Leber's Hereditary Optic Neuropathy Cells to 2,5-Hexanedione Toxicity
Get PDFLeber's hereditary optic neuropathy (LHON) is a maternally inherited blinding disease due to mitochondrial DNA (mtDNA) point mutations in complex I subunit genes, whose incomplete penetrance has been attributed to both genetic and environmental factors. Indeed, the mtDNA background defined as haplogroup J is known to increase the penetrance of the 11778/ND4 and 14484/ND6 mutations. Recently it was also documented that the professional exposure to n-hexane might act as an exogenous trigger for LHON. Therefore, we here investigate the effect of the n-hexane neurotoxic metabolite 2,5-hexanedione (2,5-HD) on cell viability and mitochondrial function of different cell models (cybrids and fibroblasts) carrying the LHON mutations on different mtDNA haplogroups. The viability of control and LHON cybrids and fibroblasts, whose mtDNAs were completely sequenced, was assessed using the MTT assay. Mitochondrial ATP synthesis rate driven by complex I substrates was determined with the luciferine/luciferase method. Incubation with 2,5-HD caused the maximal loss of viability in control and LHON cells. The toxic effect of this compound was similar in control cells irrespective of the mtDNA background. On the contrary, sensitivity to 2,5-HD induced cell death was greatly increased in LHON cells carrying the 11778/ND4 or the 14484/ND6 mutation on haplogroup J, whereas the 11778/ND4 mutation in association with haplogroups U and H significantly improved cell survival. The 11778/ND4 mutation on haplogroup U was also more resistant to inhibition of complex I dependent ATP synthesis by 2,5-HD. In conclusion, this study shows that mtDNA haplogroups modulate the response of LHON cells to 2,5-HD. In particular, haplogroup J makes cells more sensitive to its toxic effect. This is the first evidence that an mtDNA background plays a role by interacting with an environmental factor and that 2,5-HD may be a risk element for visual loss in LHON. This proof of principle has broad implications for other neurodegenerative disorders such as Parkinson's disease
Natural variation in the potency and binding sites of mitochondrial quinone-like inhibitors
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Staurosporine Induces Apoptotic Volume Decrease (AVD) in ECV304 Cells
No full textIncubation of ECV304 cells with 1 micro M staurosporine (STS) causes apoptotic cell death. In the present study, we investigate whether a significant apoptotic volume decrease (AVD) was apparent during the very early times (1 h) of the apoptotic process. Our data suggest that upregulation of Cl(-) (and possibly K(+)) channels by STS may be a very early primary event required for the subsequent onset of AVD, which results in apoptosis
Migration, Diversity, and Economic Growth. A Replication Study of Bove and Elia (World Development, 2017)
Get PDFThis study examines the antecedents of Mobile banking (M-banking) app adoption, explores post-adoption effects, and tests the moderating effect of consumer status orientation on the relationship between adoption intention and its consequences. The conceptual model hypothesized 20 relationships, including 10 moderations. Hypotheses are tested using the structural equation modeling method (PLS-SEM) on a sample of 509 individuals. The results reveal that the main variables of 'users' rational perception, namely behavioral control and terminal security, significantly influence the intention to adopt the application, which in turn impact relationship quality and financial inclusion. However, hedonic expectations do not have a significant impact on the intention to adopt the application; the impact of culture in these relationships is further established; indeed, traditional and modern values moderate the impact of the intention to adopt the application on key post-adoption factors, financial inclusion, and relationship quality. The main recommendations and limitations of the research are discussed.A recent and well known paper, Bove and Elia (2017), argues that migrants' diversity, as captured by the indexes of both fractionalization and polarization, exerts a positive effect on GDP growth. In fact, by using the same dataset and methodology, we show that the impact of diversity cannot be distinguished from that of migration itself due to the very high correlation among the corresponding variables. Also, if one disentangles migration from diversity, following Alesina et al. (2016), only migration maintains a positive impact on growth while diversity, as captured by fractionalization, turns out to be weakly and positively associated with growth, but limitedly to the 1980-2010 time span. Polarization, on the other hand, does not seem to exert any effect on growth. The question as to whether diversity is more or less beneficial in terms of economic growth remains therefore an intriguing one, and calls for more theoretical and empirical analyses, possibly based on less (geographically) aggregated data
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