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  • 11
    Electronic Resource
    Electronic Resource
    Urinary Markers of Bone Turnover in Healthy Children and Adolescents: Age-Related Changes and Effect of Puberty (1998)
    Springer
    Calcified tissue international 63 (1998), S. 369-374 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Children — Puberty — Type I collagen cross-links — type I collagen telopeptide.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. During growth, bones change their dimensions rapidly with the changes involving both formation and resorption processes. Small cross-linked peptides coming from type I collagen molecules are excreted in urine when bone is resorbed. To date, conflicting results have been presented concerning the age- and puberty-related changes of urinary markers. The purpose of the present study was to verify the effect of age, gender, and puberty on the urinary excretion of type I collagen degradation products in healthy children and adolescents. Timed spot urines from 176 children (4–20 years old) and 50 young adults were analyzed. The concentrations of N-telopeptides of type I collagen (NTx), pyridinolines (Pyr), and deoxypyridinolines (Dpyr) were measured, and the results were normalized to creatinine. Age-related changes in cross-links excretion were observed. The levels decreased with age, and a peak of excretion was shown at the beginning of adolescence. Prepubertal levels of all the markers were four- to five-fold higher than in adults, and they decreased towards adult levels in late puberty. Girls had significantly higher levels of all biochemical markers than boys at pubertal stage 2. We also observed a remarkable effect of puberty on the levels of bone degradation products that was independent of age and gender. Our results indicate that bone resorption is high in children relative to that in adults, and that urinary levels of NTx, Pyr, and Dpyr change as a function of age, gender, and puberty.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900542
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  • 12
    Electronic Resource
    Electronic Resource
    The high-pressure stability of zoisite and phase relationships of zoisite-bearing assemblages (1998)
    Springer
    Contributions to mineralogy and petrology 130 (1998), S. 162-175 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract The fluid-absent reaction 12 zoisite = 3 lawsonite + 7 grossular + 8 kyanite + 1 coesite was experimentally reversed in the model system CaO-Al2O3-SiO2-H2O (CASH) using a multi-anvil apparatus. The upper pressure stability limit for zoisite was found to extend to 5.0 GPa at 700 °C and to 6.6 GPa at 950 °C. Additional experiments both in the H2O-SiO2-saturated and in the H2O-Al2O3-saturated portions of CASH provide further constraints on high pressure phase relationships of lawsonite, zoisite, grossular, kyanite, coesite, and an aqueous fluid. Consistency of the present experiments with the H2O-saturated breakdown of lawsonite is demonstrated by thermodynamic analysis using linear programming techniques. Two sets of data consistent with databases of Berman (1988) and Holland and Powell (1990) were retrieved combining experimental phase relationships, calorimetric constraints, and recently measured elastic properties of solid phases. The best fits result in G f ,1,298 ∘,zoisite=−6,499,400 J and S 1,298 ∘,zoisite=302 J/K, and G f ,1,298 ∘,lawsonite=−4,514,600 J and S 1,298 ∘,lawsonite=220 J/K for the dataset of Holland and Powell, and G f ,1,298 ∘,zoisite=−6,492,120 J and S 1,298 ∘,zoisite=304 J/K, and G f ,1,298 ∘,lawsonite=−4,513,000 J and S 1,298 ∘,lawsonite= 218 J/K for the dataset of Berman. Examples of the usage of zoisite as a geohygrometer and as a geobarometer in rocks metamorphosed at eclogite facies conditions are worked, profiting from the thermodynamic properties retrieved here.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100050357
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  • 13
    Electronic Resource
    Electronic Resource
    Chemistry versus time in the volcanic complex of Ischia (Gulf of Naples, Italy): evidence of successive magmatic cycles (1987)
    Springer
    Contributions to mineralogy and petrology 95 (1987), S. 322-335 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract An extensive petrochemical and geochronological study of the volcanic complex of the island of Ischia has been made in order to assess the variation of the magmatic characteristics through time. The major and trace element chemistry and the mineralogy of more than 40 samples, coupled with their K/Ar ages, reveal four phases of volcanic activity: (1) prior to 150000 years B.P. — alkali-trachyte pyroclastic products; (2) 150000–75000 years B.P. — alkali-trachytic to phonolitic lava domes and minor pyroclastics; (3) 55000–20000 years B.P. — great pyroclastic emissions of trachytic and alkali-trachytic composition; (4) 10000 years B.P.-1302 A.D. — mainly lava flows, ranging from alkali-trachytes to magmas between basalt and latite. In spite of a relatively monotonous major element chemistry, the trace element contents of the rocks show a large variation (up to a factor of 9). Comparison of glass compositions with the modal phases permits us to distinguish at least four clearly established supplies of new magma to a shallow chamber. After the first three events, the magmas possibly evolved in a closed system controlled by fractional crystallization with at least one single eutectic crystallization occurring afterwards (sodalite, nepheline and alkali feldspar+aegirine and salite). During the fourth event, increasing proportions of a less evolved liquid, suddenly charged with mafic xenocrysts, contaminated the residual liquid in the chamber and generated through time more and more basic products. Their high Th/Ta and Th/Hf ratios and Ta, Nb and Ti negative anomalies suggest an orogenic tendency of the recent volcanic activity on the island of Ischia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371846
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  • 14
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    A synthetic agonist at the orphanin FQ/nociceptin receptor ORL1: Anxiolytic profile in the rat (2000)
    National Academy of Sciences
    Details
    Publication Date: 2000-04-11
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 15
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    High-temperature and high-pressure behavior of carbonates in the ternary diagram CaCO3-MgCO3-FeCO3 (2016)
    Mineralogical Society of America
    Details
    Publication Date: 2016-06-03
    Description: We report the thermal expansion and the compressibility of carbonates in the ternary compositional diagram CaCO 3 -MgCO 3 -FeCO 3 , determined by in situ X-ray powder and single-crystal diffraction. High-temperature experiments were performed by high-resolution X-ray synchrotron powder diffraction from ambient to decarbonation temperatures (25–850 °C). Single-crystal synchrotron X-ray diffraction experiments were performed in a variable pressure range (0–100 GPa), depending on the stability field of the rhombohedral structure at ambient temperature, which is a function of the carbonate composition. The thermal expansion increases from calcite, CaCO 3 , α 0 = 4.10(7) x 10 –5 K–1, to magnesite, MgCO 3 , α 0 = 7.04(2) x 10 –5 K –1 . In the magnesite-siderite (FeCO 3 ) join, the thermal expansion decreases as iron content increases, with an experimental value of α 0 = 6.44(4) x 10 –5 K –1 for siderite. The compressibility in the ternary join is higher (i.e., lower bulk modulus) in calcite and Mg-calcite [ K 0 = 77(3) GPa for Ca 0.91 Mg 0.06 Fe 0.03 (CO 3 )] than in magnesite, K 0 = 113(1) GPa, and siderite, K 0 = 125(1) GPa. The analysis of thermal expansion and compressibility variation in calcite-magnesite and calcite-iron-magnesite joins clearly shows that the structural changes associated to the order-disorder transitions [i.e., $$R\overline{3}c\phantom{\rule{0.2em}{0ex}}$$ calcite-type structure vs. $$R\overline{3}$$ CaMg(CO 3 ) 2 dolomite-type structure] do not affect significantly the thermal expansion and compressibility of carbonate. On the contrary, the chemical compositions of carbonates play a major role on their thermo-elastic properties. Finally, we use our P-V-T equation of state data to calculate the unit-cell volume of a natural ternary carbonate, and we compare the calculated volumes to experimental observations, measured in situ at elevated pressure and temperatures, using a multi-anvil device. The experimental and calculated data are in good agreement demonstrating that the equation of state here reported can describe the volume behavior with the accuracy needed, for example, for a direct chemical estimation of carbonates based on experimental unit-cell volume data of carbonates at high pressures and temperatures.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 16
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    The temperature and compositional dependence of disordering in Fe-bearing dolomites (2012)
    Mineralogical Society of America
    Details
    Publication Date: 2012-10-01
    Description: Dolomite occurs in a wide range of rock compositions, from peridotites to mafic eclogites and metasediments, up to mantle depths of more than 200 km. At low-temperatures dolomite is ordered ( R ), but transforms with increasing temperature into a disordered higher symmetry structure ( R c ). To understand the thermodynamics of dolomite, we have investigated temperature, pressure, kinetics, and compositional dependence of the disordering process in Fe-bearing dolomites. To avoid quench effects, in situ X-ray powder diffraction experiments were performed at 300–1350 K and 2.6–4.2 GPa. The long-range order parameter s , quantifying the degree of ordering, has been determined using structural parameters from Rietveld refinement and the normalized peak area variation of superstructure Bragg peaks characterizing structural ordering/disordering. Time-series experiments show that disordering occurs in 20–30 min at 858 K and in a few minutes at temperatures ≥999 K. The order parameter decreases with increasing temperature and X Fe . Complete disorder is attained in dolomite at ~1240 K, 100–220 K lower than previously thought, and in an ankeritic-dolomite s.s. with an X Fe of 0.43 at temperatures as low as ~900 K. The temperature-composition dependence of the disorder process was fitted with a phenomenological approach intermediate between the Landau theory and the Bragg-Williams model and predicts complete disorder in pure ankerite to occur already at ~470 K. The relatively low-temperature experiments of this study also constrain the breakdown of dolomite to aragonite+Fe-bearing magnesite at 4.2 GPa to temperature lower than ~800 K favoring an almost straight Clapeyron-slope for this disputed reaction.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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  • 17
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    An Experimental Study on COH-bearing Peridotite up to 3{middle dot}2 GPa and Implications for Crust-Mantle Recycling (2013)
    Oxford University Press
    Details
    Publication Date: 2013-02-13
    Description: We experimentally investigated phlogopite- and C–O–H-bearing lherzolite to model the mantle wedge fluxed by volatiles released from a subducting crustal slab. Experiments have been carried out at 900–1050°C and 1·6–3·2 GPa, at fluid- and carbon-saturated conditions. We used an end-loaded piston cylinder apparatus and a conventional double-capsule technique to constrain the redox state of the experiments, using the nickel–nickel oxide oxygen buffer (NNO). Following thermodynamic calculations, we expect inner f O 2 values to be systematically below NNO, with fluids that are mixtures of CO 2 and H 2 O. Estimated f O 2 in the runs are between FMQ –0·7 at 3 GPa and FMQ –1·1 at 1·8 GPa, values that have been reported for natural mantle-wedge xenoliths. At the conditions investigated, the hydrous phases are phlogopite and pargasitic amphibole. Whereas phlogopite is ubiquitous, amphibole disappears at 3·1 GPa at 900°C and 2·7 GPa at 1050°C, where the solidus is encountered. The amphibole-out reaction also consumes orthopyroxene and liberates water. From low to high P , we observed first carbonate-free, amphibole-bearing assemblages, then carbonate + amphibole-bearing assemblages, and finally amphibole-free, carbonate-bearing assemblages. Carbonate-free assemblages melt to produce trachyandesite at T 〉 1050°C, whereas dolomitic carbonatites have been found beyond the solidus of carbonate-bearing assemblages. Carbonates occur as dolomite at 〈1·9 GPa, 900°C and at 〈2·1 GPa, 1050°C; magnesite at 〉2·4 GPa, 900°C and 〉2·7, 1050°C; between these limits, a magnesite + dolomite-bearing assemblage constitutes a two-carbonate field. P–T pseudosections fail to reproduce the experimental results concerning amphibole breakdown and reaction positions involving carbonates. The amount of COH fluid is thought to have a major role, even in fluid-saturated peridotites. Clinopyroxene and olivine are not expected at fluid-oversaturated conditions, for which dolomite or magnesite are stable respectively. The presented results are useful for unravelling the exhumation history of orogenic lherzolites bearing COH phases and to suggest a way to transfer carbon species to the mantle wedge. We suggest that once carbon-bearing fluids react with mantle-wedge peridotites, a sort of buoyant ‘cold plume’ will form containing low-density phases such as amphibole, carbonates and carbonatitic melt. This plume could represent an important source of CO 2 and H 2 O, and it is one of a series of processes that ultimately lead to arc magmatism.
    Print ISSN: 0022-3530
    Electronic ISSN: 1460-2415
    Topics: Geosciences
    Published by Oxford University Press
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  • 18
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    The ERA-Interim reanalysis: configuration and performance of the data assimilation system (2011)
    Wiley
    Details
    Publication Date: 2011-04-29
    Description: ERA-Interim is the latest global atmospheric reanalysis produced by the European Centre for Medium-Range Weather Forecasts (ECMWF). The ERA-Interim project was conducted in part to prepare for a new atmospheric reanalysis to replace ERA-40, which will extend back to the early part of the twentieth century. This article describes the forecast model, data assimilation method, and input datasets used to produce ERA-Interim, and discusses the performance of the system. Special emphasis is placed on various difficulties encountered in the production of ERA-40, including the representation of the hydrological cycle, the quality of the stratospheric circulation, and the consistency in time of the reanalysed fields. We provide evidence for substantial improvements in each of these aspects. We also identify areas where further work is needed and describe opportunities and objectives for future reanalysis projects at ECMWF. Copyright © 2011 Royal Meteorological Society
    Print ISSN: 0035-9009
    Electronic ISSN: 1477-870X
    Topics: Geography , Physics
    Published by Wiley
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  • 19
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    Evidence of interspersed co-existing CaCO3-III and CaCO3-IIIb structures in polycrystalline CaCO3 at high pressure (2014)
    Mineralogical Society of Great Britain and Ireland
    Details
    Publication Date: 2014-05-17
    Description: New experimental data are reported on high-pressure polymorphism of CaCO 3 . The CaCO 3 -III phase was stabilized using a large-volume press device and high-resolution X-ray powder diffraction (XRPD) patterns were collected from a few mm 3 of powder sample. The interpretation of XRPD indicates that CaCO 3 -III and CaCO 3 -IIIb structures are present simultaneously and are in similar proportions. The lack of any unindexed peaks demonstrates that these two polymorphs are the only phases in this experiment, indicating that CaCO 3 -III and CaCO 3 -IIIb are the structures most likely to occur above 2.5 GPa. Relevant co-axial crystallographic matrix transformations from lower-pressure polymorphs to both CaCO 3 -III and CaCO 3 -IIIb are discussed to illustrate a further possible occurrence of co-existing and interspersed stable polymorphs in carbonate systems.
    Print ISSN: 0026-461X
    Electronic ISSN: 1471-8022
    Topics: Geosciences
    Published by Mineralogical Society of Great Britain and Ireland
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  • 20
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    Dolomite discloses a hidden history of subducting slabs (2014)
    Mineralogical Society of America
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    Publication Date: 2014-05-16
    Description: Dolomite and magnesite are the major carbon reservoirs in the subducted oceanic lithosphere. Compositional complexities in dolomite and magnesite solid solutions are often overlooked, but normal and oscillatory zoning in dolomite from mafic eclogites of Tianshan (China) demonstrates that prograde pressure—temperature histories and interactions with coexisting mixed fluids can be recorded in carbonates. Thermodynamic modeling and comparison with experimental results warn against a simplistic approach to carbonate-bearing assemblages and show that magnesite occurrence is not an unambiguous evidence for ultrahigh-pressure metamorphism.
    Print ISSN: 0003-004X
    Electronic ISSN: 1945-3027
    Topics: Geosciences
    Published by Mineralogical Society of America
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