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Indonesia hosts the largest number of active volcanoes, several of which are renowned for climate-changing historical eruptions. This pedigree might suggest a substantial fraction of global volcanic sulfur emissions from Indonesia and are intrinsically driven by sulfur-rich magmas. However, a paucity of observations has hampered evaluation of these points—many volcanoes have hitherto not been subject to emissions measurements. Here we report new gas measurements from Indonesian volcanoes. The combined SO2 output amounts to 1.15 ± 0.48 Tg/yr. We estimate an additional time-averaged SO2 yield of 0.12-0.54 Tg/yr for explosive eruptions, indicating a total SO2 inventory of 1.27-1.69 Tg/yr for Indonesian. This is comparatively modest—individual volcanoes such as Etna have sustained higher fluxes. To understand this paradox, we compare the geodynamic, petrologic, magma dynamical and shallow magmatic-hydrothermal processes that influence the sulfur transfer to the atmosphere. Results reinforce the idea that sulfur-rich eruptions reflect long-term accumulation of volatiles in the reservoirs.

Abundant granitic rocks exposed in ancient mountain belts suggest that crustal melting plays a major role in orogenic processes. However, complex field relations and superposition of multiple tectonic events make it difficult to determine the role of melting in orogenesis. In contrast, geophysical measurements image present-day crustal conditions but cannot discriminate between partial melt and aqueous fluids. Here we connect pressure–temperature paths of Himalayan Miocene crustal rocks to the present-day conditions beneath the Tibetan plateau imaged with geophysical data. We use measurements of electrical conductivity to show that 4–16% water-rich melt is required to explain the crustal conductivity in the north-western Himalaya. In southern Tibet, higher melt fractions >30% reflect a crust that is either fluid-enriched (+1% H2O) or hotter (+100 °C) compared to the Miocene crust. These melt fractions are high enough for the partially molten rocks to be significantly weaker than the solid crust., Crustal melting may play a fundamental role in orogenic processes, but quantifying crustal melt remains difficult. Here, the authors combine pressure-temperature paths, electrical conductivity and geophysical data to elucidate the melting conditions in Tibet since the Miocene.

Erratum to: Bull Volcanol (2017) 79: 36 DOI 10.1007/s00445-017-1114-z; International audience

Forecasting future eruptions of Vesuvius is an important challenge for volcanologists, as its reawakening could threaten the lives of 700,000 people living near the volcano1,2. Critical to the evaluation of hazards associated with the next eruption is the estimation of the depth of the magma reservoir, one of the main parameters controlling magma properties and eruptive style. Petrological studies have indicated that during past activity, magma chambers were at depths between 3 and 16km (refs 3– 7). Geophysical surveys have imaged some levels of seismic attenuation, the shallowest of which lies at 8–9km depth8, and these have been tentatively interpreted as levels of preferential magma accumulation. By using experimental phase equilibria, carried out on material from four main explosive events at Vesuvius, we show here that the reservoirs that fed the eruptive activity migrated from 7–8km to 3–4km depth between the AD 79 (Pompeii) and AD 472 (Pollena) events. If data from the Pomici di Base event 18.5 kyr ago9 and the 1944 Vesuvius eruption7 are included, the total upward migration of the reservoir amounts to 9–11 km. The change of preferential magma ponding levels in the upper crust can be attributed to differences in the volatile content and buoyancy of ascending magmas, as well as to changes in local stress field following either caldera formation10 or volcano spreading11. Reservoir migration, and the possible influence on feeding rates12, should be integrated into the parameters used for defining expected eruptive scenarios at Vesuvius.

The compositions of volcanic gases can be used by geologists to monitor volcanic activity or as a pointer to how the composition of the atmosphere has evolved with time. It is implicitly assumed that these gases faithfully reflect the conditions, in particular the redox state, of their source magma. But detailed physico-chemical modelling of the degassing processes reveals that this assumption is not generally valid and that the redox state of erupted magmas does not necessarily reflect the redox state of the gases emitted into the atmosphere. A coupled chemical–physical model of conduit flow shows that the oxidation state of an ascending magma is strongly dependent on both the composition and amount of gas in the reservoir. Volatiles carried by magmas, either dissolved or exsolved, have a fundamental effect on a variety of geological phenomena, such as magma dynamics1,2,3,4,5 and the composition of the Earth’s atmosphere6. In particular, the redox state of volcanic gases emanating at the Earth’s surface is widely believed to mirror that of the magma source, and is thought to have exerted a first-order control on the secular evolution of atmospheric oxygen6,7. Oxygen fugacity ( ) estimated from lava or related gas chemistry, however, may vary by as much as one log unit8,9,10, and the reason for such differences remains obscure. Here we use a coupled chemical–physical model of conduit flow to show that the redox state evolution of an ascending magma, and thus of its coexisting gas phase, is strongly dependent on both the composition and the amount of gas in the reservoir. Magmas with no sulphur show a systematic increase during ascent, by as much as 2 log units. Magmas with sulphur show also a change of redox state during ascent, but the direction of change depends on the initial in the reservoir. Our calculations closely reproduce the H2S/SO2 ratios of volcanic gases observed at convergent settings, yet the difference between in the reservoir and that at the exit of the volcanic conduit may be as much as 1.5 log units. Thus, the redox state of erupted magmas is not necessarily a good proxy of the redox state of the gases they emit. Our findings may require re-evaluation of models aimed at quantifying the role of magmatic volatiles in geological processes.

To monitor infant care practices associated with risks for sudden infant death, 400 Belgian families with infants less than 6 months old were questioned by 21 paediatricians during routine visits to local paediatric practices and well baby services (11 in urban centres, 10 in rural areas). Because of incomplete information, 35 families were excluded. Of the 365 mothers included in the study, 36.1% had under 7 years of schooling, 38.4% less than 13 years, and 25.5% had a professional school or a university degree. Risk factors for sudden infant death were found in 208 (56.9%) families: a usual non-supine sleep position (31.5% of the infants); sleeping under a duvet (24.1%); mothers smoking during and after gestation (16.4%); a high room temperature (6.6%); use of sedatives (3.8%); necklaces or plastic film in the cot (2.5%); and soft beddings (2.2%). Maternal education, but not the fathers' profession was significantly related to the number of risk factors (mean odds ratio of 4.4; 95% CI: 1.5 to 5.3; P=0.001). A stepwise logistic regression analysis identified the mother's length of schooling as the single most significant independent factor for the presence of risk (P

We analyze the joint convergence of sequences of discounted stock prices and Radon-Nicodym derivatives of the minimal martingale measure when interest rates are stochastic. Therefrom we deduce the convergence of option values in either complete or incomplete markets. We illustrate the general result by two main examples: a discrete time i.i.d. approximation of a Merton type pricing model for options on stocks and the trinomial tree of Hull and White for interest rate derivatives.

wherem ∈ F is a given function andH : F → F is a compact linear operator. Data are used to estimate functionm and operatorH , and then an estimator mn of the functionm is obtained by solving the sample counterpart of Eq. (1). Professors Mammen and Yu overview several useful results to study the large sample properties of the estimator mn and present a series of interesting examples, focussing on additive models. In my discussion, I will point out the relevance of this paper from the view point of econometrics. As an example I consider the nonparametric estimation of integral equations arising from rational expectation models. This example is introduced in Carrasco, Florens, and Renault (2007). Here the example is developed and used to illustrate Theorem 1 of the paper. Following the seminal paper of Lucas (1978), let us consider a pure exchange economy with identical agents and an exogenous technology producing the output yt at time t .1 Output is stochastic and follows a time-homogeneous Markov process with transition distribution F (y|x) = P [yt ≤ y|yt−1 = x]. Ownership of the production technology is traded in a competitive stock market. The representative agent maximizes the expected lifetime utility from consumption E [∑ ∞ t=1 β U(ct) ] under a budget constraint, where U(c) denotes the utility from consumption c (time-separable), and β ∈ (0, 1) is the time discount parameter (constant). In this economy, consumption at equilibrium is ct = yt , and all shares of the production technology are held by the representative agent. Thus, the only equilibrium quantity to be determined is the asset price. The price pt at date t of a share in the production technology is a function of theMarkov state of the economy yt , that is pt = m(yt). Lucas (1978) shows that functionm satisfies the equation

We give analytical pricing formulae for path dependent options on yields in the framework of the affine term structure model. More precisely, European call options such as the arithmetic average call, the call on maximum and the lookback call are examined. For the two last options approximate formulae using the law of hitting times of an Ornstein-Uhlenbeck process are proposed. Numerical implementation is also briefly discussed and results are given in the case of the arithmetic average option.

Solidus temperatures of quartz–alkali feldspar assemblages in the haplogranite system (Qz-Ab-Or) and subsystems in the presence of H2O-H2 fluids have been determined at 1, 2, 5 and 8 kbar vapour pressure to constrain the effects of redox conditions on phase relations in quartzofeldspathic assemblages. The hydrogen fugacity (fH2) in the fluid phase has been controlled using the Shaw membrane technique for moderately reducing conditions (fH2 fO2 > WM] shows that increasing fH2 produces a slight increase of the solidus temperatures (up to 30 °C) of quartz–alkali feldspar assemblages in the presence of H2O-H2 fluids between 1 and 5 kbar total pressure.

A study of cerium in zircon minerals has allowed an assessment of the redox conditions that prevailed when Earth's earliest magmas formed. The results suggest that the mantle became oxidized sooner than had been thought. See Letter p.79 The composition of Earth's earliest atmosphere, which accumulated more than four billion years ago during the Hadean eon, may have been influenced by magmatic outgassing of volatiles from Earth's interior. This paper reports a redox-sensitive calibration to determine the oxidation state of Hadean magmatic melts based on the incorporation of cerium into zircon crystals. The authors find that the melts have oxygen fugacities that are consistent with the idea that Earth's mantle reached its present-day oxidation state as early as 4.35 billion years ago. The findings suggest that outgassing of Earth's interior about 200 million years into the history of Solar System formation would not have resulted in a reducing atmosphere.

Direct evidence for the role of volatiles in magmatic ore formation has been elusive. Magma degassing at Merapi volcano in Indonesia is found to be directly linked to the selective leaching of metals from sulphide melts that ultimately form ore deposits.

Replying to J. F. Kasting, D. C. Catling & K. Zahnle , 10.1038/nature11274 (2012) Kasting 1 question the model of ref. 2, in which we suggest that the oxygenation of the atmosphere, around 2.45 Gyr ago, was promoted by the emergence of subaerial volcanism, producing volcanic gases with much more elevated SO2/H2S ratios than submarine volcanism.

Sighs are important components of normal breathing. They occur isolated or associated with respiratory pauses. Functional residual capacity and lung compliance increase after sighs. Sighs have been shown to be part of an arousal reaction in infants and to induce heart rate modifications. We investigated the influence of sighs on the autonomic balance in infants. METHODS: 107 sighs (a single breath of at least twice the amplitude of the preceding breaths, not followed by an apnea) from 23 term infants were selected. The selection was made in conditions known not to interfere with spontaneous HR variability (quiet sleep,absence of movements, apnea or false detections of QRS during the 2 preceding and following minutes. Spectral analysis of RR variability was performed on the 2 minutes preceding and the 2 minutes following the sigh. To study the role of the ANS in the development of a sigh, spectral analysis of the period just before the sigh and of the 2 preceding minutes were compared. RESULTS: The 2 minutes following the sigh were characterized by an increased RR interval (p 0.001), an increased total power (p

Arising from: A. E. Saal, E. H. Hauri, C. H. Langmuir & M. R. Perfit Nature 419, 451–455 (2002); Saal et al. reply Assessing the conditions under which magmas become fluid-saturated has important bearings on the geochemical modelling of magmas because volatile exsolution may profoundly alter the behaviour of certain trace elements that are strongly partitioned in the coexisting fluid1. Saal et al.2 report primitive melt inclusions from dredged oceanic basalts of the Siqueiros transform fault, from which they derive volatile abundances of the depleted mantle, based on the demonstration that magmas are not fluid-saturated at their eruption depth and so preserve the mantle signature in terms of their volatile contents. However, in their analysis, Saal et al.2 consider only fluid–melt equilibria, and do not take into account the homogeneous equilibria between fluid species, which, as we show here, may lead to a significant underestimation of the pressure depth of fluid saturation.