887 research outputs found

    Formation and evolution of a metasomatized lithospheric root at the motionless Antarctic plate: the case of East Island, Crozet Archipelago (Indian Ocean)

    Get PDF
    Sitting atop the nearly stagnant Antarctic plate (ca. 6.46 mm/yr), the Crozet archipelago midway between Madagascar and Antarctica constitutes a region of unusually shallow (1543-1756 m below sea level) and thickened oceanic crust (10-16.5 km), high geoid height, and deep low-velocity zone, which may reflect the surface expression of a mantle plume. Here, we present new major and trace element data for Quaternary sub-aerial alkali basalts from East Island, the easterly and oldest island (ca. 9 Ma) of the Crozet archipelago. Crystallization at uppermost mantle depth and phenocryst accumulation have strongly affected their parental magma compositions. Their trace element patterns show a large negative K anomaly relative to Ta-La, moderate depletions in Rb and Ba with respect to Th-U, and heavy rare earth element (HREE) depletions relative to light REE. These characteristics allow limits to be placed upon the composition and mineralogy of their mantle source. The average trace element spectrum of East Island basalts can be matched by melting of about 2 % of a garnet-phlogopite-bearing peridotite source. The stability field of phlogopite restricts melting depth to lithospheric levels. The modelled source composition requires a multistage evolution, where the mantle has been depleted by melt extraction before having been metasomatized by alkali-rich plume melts. The depleted mantle component may be sourced by residual mantle plume remnants stagnated at the melting locus due to a weak lateral flow velocity inside the melting regime, whose accumulation progressively edifies a depleted lithospheric root above the plume core. Low-degree alkali-rich melts are likely derived from the plume source. Such a mantle source evolution may be general to both terrestrial and extraterrestrial environments where the lateral component velocity of the mantle flow field is extremely slow

    Using the pain principle to provide a new approach to invasive treatments and end-of-life care

    Get PDF
    End-of-life issues involving small babies are particularly challenging for doctors, particularly pediatricians as there are complex issues involved, including long-term disabilities (1) and the parents' wishes (1). Evaluations can be based on statistical risks (2) and case-by-case issues. Some authors (3) suggest that intensive care can be withheld when consciousness is compromised, but that raises questions about what level of consciousness equates to a baby being completely compromised (4). Other authors have questioned whether suspending therapies when the baby is not at their end-of-life is ethically right. Concerns have also been expressed that there is a risk that babies lives are undervalued, in comparison with older patients, because their life support is removed more easily than when adults have a similar prognosis

    Relating pain intensity of newborns to onset of nonlinear phenomena in cry recordings

    Full text link
    The cries of several full term newborns, recorded during blood sampling, were analyzed. Spectrograms showed the appearance of irregular patterns related to the pain assessed using the method of the DAN scale. In particular, the appearance of Noise concentration Patterns (NP) in spectrograms was related to the increase of the pain suffered by the newborns. In this scenario, pain constitutes a bifurcation parameter for the vocal folds dynamic, inducing a Ruelle-Takens-Newhouse chaotic transition.Comment: 15 pages, 4 figures, 1 table. Accepted for publication in Phys. Lett.

    Rapakivi texture in porphyritic dikes within the Karavanke Granitic Massif (Slovenia)

    Get PDF
    The northern Karavanke Granitic Massif straddles the Slovenian–Austrian border. The investigated area lies in northern Slovenia, and extends from the western Slovenian–Austrian border to the east for about 30 km, with a maximum width of 2 km. The massif exhibits a bimodal magmatic association comprising mainly syenogranite and syenite with contemporaneous gabbroic rocks. Rocks of intermediate composition are less abundant and show field, textural and chemical features suggesting that they have formed as a result of the interaction (mixing and mingling) between felsic and mafic magmas. Plagioclasemantled alkali feldspars occur in dikes of porphyritic syenite, which cut larger bodies of gabbroic rocks. Field, mineralogical, petrographic and geochemical evidences suggest that the porphyritic syenite is a hybrid rock, formed by the interaction of mafic and felsic magmas. The formation of plagioclase-mantled alkali feldspar can be explained by the introduction of alkali feldspar from felsic, syenogranitic magma into more mafic magma, causing local undercooling in the portion of mafic magma surrounding the crystals. This resulted in the growth of cellular plagioclase, with quartz infilling, in a thermally and compositionally equilibrating system

    Le epistole di Francesco da Fiano (1350 ca-1421)

    Get PDF
     This analysis of the all surviving letters of Francesco da Fiano sheds new light on da Fiano’s role as a promulgator of the humanistic movement of late fourteenth- and early fifteenth-century Rome and Naples. A chancellor in the papal curia, da Fiano was also a humanist who recognized how letter-writing could serve as a vehicle of intellectual expression. The essay reconstructs the life of da Fiano on the evidence of archival documents and surviving works. The cultural and historical importance of da Fiano is particularly apparent in the letters between him and Petrarch, Salutati and the major writers of the time. His importance is also reflected in his correspondence with several kings and nobles, some of whom were briefly his protectors and patrons. The style of the letters is consonant with the conventions of the Roman curia of the late fourteenth century, but the letters also incorporate several novelties proposed by Petrarch and Salutati

    Modified Sensory Stimulation Using Breastmilk for Reducing Pain Intensity in Neonates in Indonesia: A Randomized Controlled Trial.

    Get PDF
    Abstract Purpose Several studies have shown that oral sucrose reduces pain in newborns. However, sucrose has no efficacy in eliminating pain and long-term effects remain unclear. Breast milk may be useful as an alternative, safe sweet solution. Sensorial saturation (SS) is a multisensory analgesic non-pharmacological treatment, which includes touch and sounds as distractors. This study aimed to compare the analgesic effects of SS with sucrose (SSS), SS with breast milk (SSB), and oral sucrose alone (S24%) in neonates undergoing venipuncture. Design and methods This was a randomized controlled trial conducted on 108 neonates who underwent venipuncture at neonatology wards. All babies were randomly assigned to one of three groups: two intervention groups and one control group. Pain response was assessed using the premature infant pain profile—revised (PIPP-R). Data analysis was conducted using the Kruskal–Wallis test and Mann–Whitney U test. Results SSB and SSS were more effective than S24% (p = 0.001). No difference was observed between SSB and SSS (p = 0.669). Conclusion Multisensory stimulation is more effective in reducing pain than unimodal (oral sucrose) analgesia. Breast milk can be used as a sensory gustatory stimulus in multisensory stimulation to reduce pain intensity in neonates, and demonstrates a similar analgesic effect to sucrose. Practice implications The study findings suggest that neonatal nurses could use SSB for management of pain. This intervention could serve as an effective, inexpensive, and safe non-pharmacological analgesic. Additional testing of this intervention is warranted to support its use as an evidence-based pain reduction approach

    Latest Triassic onset of the Central Atlantic Magmatic Province (CAMP) volcanism in the Fundy Basin (Nova Scotia): New stratigraphic constraints

    Get PDF
    In this paper we investigate the stratigraphic relationship between the emplacement of the CAMP basalts and the Triassic–Jurassic (Tr–J) boundary in the Fundy Basin (Nova Scotia, Canada). This is one of the best exposed of the synrift basins of eastern North America (ENA) formed as a consequence of the rifting that led to the formation of the Atlantic Ocean. The Triassic palynological assemblages found in the sedimentary rocks below (uppermost Blomidon Formation) and just above the North Mountain Basalt (Scots Bay Member of the McCoy Brook Formation) indicate that CAMP volcanism, at least in Nova Scotia, is entirely of Triassic age, occurred in a very short time span, and may have triggered the T–J boundary biotic and environmental crisis. The palynological assemblage from the Blomidon Formation is characterised by the dominance of the Circumpolles group (e.g. Gliscopollis meyeriana, Corollina murphyae, Classopollis torosus) which crosses the previously established Tr–J boundary.The Triassic species Patinasporites densus disappears several centimetres below the base of the North Mountain basalt, near the previously interpreted Tr–J boundary. The lower strata of the Scots Bay Member yielded a palynological assemblage dominated by Triassic bisaccate pollens (e.g Lunatisporites acutus, L. rhaeticus Lueckisporites sp., Alisporites parvus) with minor specimens of the Circumpolles group. Examination of the state of preservation and thermal alteration of organic matter associated with the microfloral assemblages precludes the possibility of recycling of the Triassic sporomorphs from the older strata. Our data argue against the previous definition of the Tr–J boundary in the ENA basins, which was based mainly on the last occurrence of P. densus. Consequently, it follows that the late Triassic magnetostratigraphic correlations should be revised considering that chron E23r, which is correlated with the last occurrence of P. densus in the Newark basin, does not occur at the Tr–J boundary but marks rather a late Triassic (probably Rhaetian) reversal

    40Ar/39Ar ages of CAMP in North America: implications for the Triassic-Jurassic boundary and the 40K decay constant bias

    Get PDF
    The Central Atlantic magmatic province (CAMP) is one of the largest igneous provinces on Earth (>107 km²) and spanning four continents. Recent high-precision 40Ar/39Ar dating of mineral separates has provided important constraints on the age, duration, and geodynamic history of CAMP. Yet, the North American CAMP is strikingly under-represented in this dating effort. Here we present 13 new statistically robust plateau, mini-plateau and isochron ages obtained on plagioclase and sericite separates from lava flows from the Fundy (n = 10; Nova Scotia, Canada) and Hartford and Deerfield (n = 3; U.S.A.) basins. Ages mostly range from 198.6 ± 1.1 to 200.1 ± 1.4 Ma (2σ), with 1 date substantially younger at 190.6 ± 1.0 Ma. Careful statistical regression shows that ages from the upper (199.7.0 ± 1.5 Ma) and bottom (200.1 ± 0.9 Ma) units of the lava pile in the Fundy basin are statistically indistinguishable, confirming a short duration emplacement (<< 1.8 Ma; ≤1 Ma). Three ages obtained on the Hartford (198.6 ± 2.0 Ma and 199.8 ± 1.1 Ma) and Deerfield (199.3 ± 1.2 Ma) basins were measured on sericite from the upper lava flow units. We interpret these dates as reflecting synemplacement hydrothermal activity within these units. Collectively, CAMP ages gathered so far suggest a short duration of the main magmatic activity (2-3 Ma), but also suggest the possibility of a temporal migration of the active magmatic centers from north to south. Such a migration challenges a plume model that would postulate a radial outward migration of the magmatism and is more compatible with other models such as the supercontinent global warming hypothesis. When compared to the age of the Triassic-Jurassic boundary, the filtered CAMP age database suggests that the onset of the magmatic activity precedes the limit by at least few hundred thousand years, therefore suggesting a causal relationship between CAMP and the end of Triassic mass extinction. An age at 191 Ma possibly suggests a minor CAMP late tailing activity (190-194 Ma) which has already observed for dykes and sills in Africa and Brazil. We speculate that, if real, this late activity can be due to a major extensional event, possibly heralding the oceanisation process at ~190 Ma. Comparison between high quality U/Pb and 40Ar/39Ar ages of pegmatite lenses from the North Mountain basalts confirms a ~1% bias between the two chronometers. This discrepancy is likely attributed to the miscalibration of the 40K decay constants, in particular the electron capture branch
    • …
    corecore