Rb-Sr systematics of volcanic rocks and alteration minerals of ODP Hole 104-642E

Subaerially erupted tholeiites at Hole 642E were never exposed to the high-temperature seawater circulation and alteration conditions that are found at subaqueous ridges. Alteration of Site 642 rocks is therefore the product of the interaction of rocks and fluids at low temperatures. The alteration mineralogy can thus be used to provide information on the geochemical effects of low temperature circulation of seawater. Rubidium-strontium systematics of leached and unleached tholeiites and underlying, continentally-derived dacites reflect interactions with seawater in fractures and vesicular flow tops. The secondary mineral assemblage in the tholeiites consists mainly of smectite, accompanied in a few flows by the assemblage celadonite + calcite (+/- native Cu). Textural relationships suggest that smectites formed early and that celadonite + calcite, which are at least in part cogenetic, formed later than and partially at the expense of smectite. Smectite precipitation occurred under variable, but generally low, water/rock conditions. The smectites contain much lower concentrations of alkali elements than has been reported in seafloor basalts, and sequentially leached fractions of smectite contain Sr that has not achieved isotopic equilibrium. 87Sr/86Sr results of the leaching experiments suggest that Sr was mostly derived from seawater during early periods of smectite precipitation. The basalt-like 87Sr/86Sr of the most readily exchangeable fraction seems to suggest a late period of exposure to very low water /rock. Smectite formation may have primarily occurred in the interval between the nearly 58-Ma age given by the lower series dacites and the 54.5 +/- 0.2 Ma model age given by a celadonite from the top of the tholeiitic section. The 54.5 +/- 0.2 Ma Rb-Sr model age may be recording the timing of foundering of the Voring Plateau. Celadonites precipitated in flows below the top of the tholeiitic section define a Rb-Sr isochron with a slope corresponding to an age of 24.3 +/- 0.4 Ma. This isochron may be reflecting mixing effects due to long-term chemical interaction between seawater and basalts, in which case the age provides only a minimum for the timing of late alteration. Alternatively, inferrential arguments can be made that the 24.3 +/- 0.4 isochron age reflects the timing of the late Oligocene-early Miocene erosional event that affected the Norwegian-Greenland Sea. Correlation of 87Sr/86Sr and 1/Sr in calcites results in a two-component mixing model for late alteration products. One end-member of the mixing trend is Eocene or younger seawater. Strontium from the nonradiogenic endmember can not, however, have been derived directly from the basalts. Rather, the data suggest that Sr in the calcites is a mixture of Sr derived from seawater and from pre-existing smectites. For Site 642, the reaction involved can be generalized as smectite + seawater ++ celadonite + calcite. The geochemical effects of this reaction include net gains of K and CO2 by the secondary mineral assemblage. The gross similarity of the reactions involved in late, low-temperature alteration at Site 642 to those observed in other sea floor basalts suggests that the transfer of K and C02 to the crust during low-temperature seawater-ocean crust interactions may be significant in calculations of global fluxes.

Spatial distribution and morphometric analysis of thermokarst lakes and other water bodies : Case study from the sporadic permafrost region, Tavvavuoma, Sweden

Projected air and ground temperatures are expected to be higher in Arctic and sub-Arcticlatitudes and with temperatures already close to the limit where permafrost can exist,resistance against degradation is low. With thawing permafrost, the landscape is modifiedwith depression in which thermokarst lakes emerge. In permafrost soils a considerableamount of soil organic carbon is stored, with the potential of altering climate even furtherif expansion and formation of new thermokarst lakes emerge, as decay releasesgreenhouse gases (C02 and CH4) to the atmosphere. Analyzing the spatial distribution andmorphometry over time of thermokarst lakes and other water bodies, is of importance inaccurately predict carbon budget and feedback mechanisms, as well as to assess futurelandscape layout and these features interaction. Different types of high-spatial resolutionaerial and satellite imageries from 1963, 1975, 2003, 2010 and 2015, were used in bothpre- and post-classification change detection analyses. Using object oriented segmentationin eCognition combined with manual adjustments, resulted in digitalized water bodies>28m2 from which direction of change and morphometric values were extracted. Thequantity of thermokarst lakes and other water bodies was in 1963 n=92, with succeedingyears as a trend decreased in numbers, until 2010-2015 when eleven water bodies wereadded in 2015 (n=74 to n=85). In 1963-2003, area of these water bodies decreased with50 651m2 (189 446-138 795m2) and continued to decrease in 2003-2015 ending at 129337m2. Limnicity decreased from 19.9% in 1963 to 14.6% in 2003 (-5.3%). In 2010 and2015 13.7-13.6%. The late increase in water bodies differs from an earlier hypothesis thatsporadic permafrost regions experience decrease in both area and quantity of thermokarstlakes and water bodies. During 1963-2015, land gain has been in dominance of the ratiobetween the two competing processes of expansion and drainage. In 1963-1975, 55/45%,followed by 90/10% in 1975-2003. After major drainage events, land loss increased to62/38% in 2010-2015. Drainage and infilling rates, calculated for 15 shorelines werevaried across both landscape and parts of shorelines, with in average 0.17/0.15/0.14m/yr.Except for 1963-1975 when rate of change in average was in opposite direction (-0.09m/yr.), likely due to evident expansion of a large thermokarst lake. Using a squaregrid, distribution of water bodies was determined, with an indistinct cluster located in NEand central parts. Especially for water bodies <250m2, which is the dominant area classthroughout 1963-2015 ranging from n=39-51. With a heterogeneous composition of bothsmall and large thermokarst lakes, and with both expansion and drainage altering thelandscape in Tavvavuoma, both positive and negative climate feedback mechanisms are inplay - given that sporadic permafrost still exist.

A new strategy for selecting and evaluating physical solvents for gas absorption

This work describes how the physical properties of a solvent affect the design variables of a physical gas absorption process. The role of every property in determining the capital and the running cost of a process has been specified. Direct mathematical relationships have been formulated between every item of capital or running cost and the properties which are related to that item. The accuracy of the equations formulated has been checked by comparing their outcome with some actual design data. A good agreement has been found. The equations formulated may be used to evaluate on the basis of economics any suggested new solvents. A group of solvents were selected for evaluation. Their physical properties were estimated or collected as experimental data. The selected ones include three important solvents, the first is polyethylene glycol dimethyl ether (Selexol) which represents the currently most successful one, The other two solvents are acetonyl acetone (B2) and n-formyl morpholine which have been suggested previously as potential credible alternatives to the current ones. The important characteristics of: acetonyl acetone are its high solubility and its low viscosity, while the n-formyl morpholine is characterised by its low vapour pressure and its high selectivity. It was found that acetonyl acetone (B2) is the most attractive solvent for commercial applications particularly for process configurations that:include heat exchangers and strippers. The effect of the process configuration on the selected solvent was investigated in detail and it was found that there is no universal solvent which is the best for any process configuration, but that there is a best solvent for a given process configuration. In previous work, acetonyl acetone was suggested as a commercially promising physical solvent. That suggestion was not fully based on experimental measurement of all the physical properties. The viscosity of acetonyl acetone and its solubility at 1 atm were measured but the vapour pressure and the solubility of C02 and CH4 at high pressure were predicted. In this work, the solubilities of C02, CH4 and C3H8 in acetenyl acetone were measured for a partial pressure range of (2 ~ 22) bar at 25°C, The vapour pressure of this solvent was also measured, and the Antoine equation was formulated from tbe experimental data. The experimental data were found to be not In agreement with the predicted ones, so acetonyl acetone was re-evaluated according to the experimental data. It was found that this solvent can be recommended for further trials in a pilot plant study or for small scale commercial units.

On the Coherence Between Probability and Possibility Measures

* This paper is supported by CICYT (Spain) under Project TIN 2005-08943-C02-01.

Contradiction versus Selfcontradiction in Fuzzy Logic

* This work is partially supported by CICYT (Spain) under project TIN 2005-08943-C02-001 and by UPM-CAM (Spain) under project R05/11240.

Charged-current inclusive neutrino cross sections in the SuperScaling model

SuperScaling model (SuSA) predictions to neutrino-induced charged-current pi(+) production in the Delta-resonance region are explored under MiniBooNE experimental conditions. The SuSA charged-current pi(+) results are in good agreement with data on neutrino flux-averaged double-differential cross sections. The SuSA model for quasielastic scattering and its extension to the pion production region are used for predictions of charged-current inclusive neutrino-nucleus cross sections. Results are also compared with the T2K experimental data for inclusive scattering.

The AGN, star-forming, and morphological properties of luminous ir-bright/optically-faint galaxies

We present the active galactic nucleus (AGN), star-forming, and morphological properties of a sample of 13 MIR-luminous (∫_24 700 μJy) IR-bright/optically-faint galaxies (IRBGs, ∫_24/f_R≲ 1000). While these z ∼ 2 sources were drawn from deep Chandra fields with >200 ks X-ray coverage, only seven are formally detected in the X-ray and four lack X-ray emission at even the 2σ level. Spitzer InfraRed Spectrograph (IRS) spectra, however, confirm that all of the sources are AGN-dominated in the mid-IR, although half have detectable polycyclic aromatic hydrocarbon (PAH) emission responsible for ∼25% of their mid-infrared flux density. When combined with other samples, this indicates that at least 30%–40% of luminous IRBGs have star formation rates in the ultraluminous infrared galaxy (ULIRG) range (∼100–2000 M_⨀ yr^−1). X-ray hardness ratios and MIR to X-ray luminosity ratios indicate that all members of the sample contain heavily X-ray obscured AGNs, 80% of which are candidates to be Compton thick. Furthermore, the mean X-ray luminosity of the sample, log L_2–10 keV(erg s^−1) ∼44.6, indicates that these IRBGs are Type 2 QSOs, at least from the X-ray perspective. While those sources most heavily obscured in the X-ray are also those most likely to display strong silicate absorption in the mid-IR, silicate absorption does not always accompany X-ray obscuration. Finally, ∼70% of the IRBGs are merger candidates, a rate consistent with that of sub-mm galaxies (SMGs), although SMGs appear to be physically larger than IRBGs. These characteristics are consistent with the proposal that these objects represent a later, AGN-dominated, and more relaxed evolutionary stage following soon after the star-formation-dominated one represented by the SMGs.

Infrared Excess sources: Compton thick QSOs, low-luminosity Seyferts or starbursts?

We explore the nature of Infrared Excess sources (IRX), which are proposed as candidates for luminous [L_X(2–10 keV) > 10^43 erg s^−1] Compton thick (NH > 2 × 1024 cm−2) QSOs at z≈ 2. Lower redshift, z≈ 1, analogues of the distant IRX population are identified by first redshifting to z= 2 the spectral energy distributions (SEDs) of all sources with secure spectroscopic redshifts in the AEGIS (6488) and the GOODS-North (1784) surveys and then selecting those that qualify as IRX sources at that redshift. A total of 19 galaxies are selected. The mean redshift of the sample is z≈ 1. We do not find strong evidence for Compton thick QSOs in the sample. For nine sources with X-ray counterparts, the X-ray spectra are consistent with Compton thin active galactic nucleus (AGN). Only three of them show tentative evidence for Compton thick obscuration. The SEDs of the X-ray undetected population are consistent with starburst activity. There is no evidence for a hot dust component at the mid-infrared associated with AGN heated dust. If the X-ray undetected sources host AGN, an upper limit of L_X(2–10 keV) = 10^43 erg s^−1 is estimated for their intrinsic luminosity. We propose that a large fraction of the z≈ 2 IRX population is not Compton thick quasi-stellar objects (QSOs) but low-luminosity [L_X(2–10 keV) < 10^43 erg s^−1], possibly Compton thin, AGN or dusty starbursts. It is shown that the decomposition of the AGN and starburst contribution to the mid-IR is essential for interpreting the nature of this population, as star formation may dominate this wavelength regime.

Improving the identification of high-z Herschel sources with position priors and optical/NIR and FIR/mm photometric redshifts

We present preliminary results about the detection of high redshift (U)LIRGs in the Bullet cluster field by the PACS and SPIRE instruments within the Herschel Lensing Survey (HLS) Program. We describe in detail a photometric procedure designed to recover robust fluxes and deblend faint Herschel sources near the confusion noise. The method is based on the use of the positions of Spitzer/MIPS 24 μm sources as priors. Our catalogs are able to reliably (5σ) recover galaxies with fluxes above 6 and 10 mJy in the PACS 100 and 160 μm channels, respectively, and 12 to 18 mJy in the SPIRE bands. We also obtain spectral energy distributions covering the optical through the far-infrared/millimeter spectral ranges of all the Herschel detected sources, and analyze them to obtain independent estimations of the photometric redshift based on either stellar population or dust emission models. We exemplify the potential of the combined use of Spitzer position priors plus independent optical and IR photometric redshifts to robustly assign optical/NIR counterparts to the sources detected by Herschel and other (sub-)mm instruments.

Local luminous infrared galaxies. I. Spatially resolved observations with the Spitzer infrared spectrograph

We present results from the Spitzer Infrared Spectrograph spectral mapping observations of 15 local luminous infrared galaxies (LIRGs). In this paper, we investigate the spatial variations of the mid-IR emission which includes fine structure lines, molecular hydrogen lines, polycyclic aromatic features (PAHs), continuum emission, and the 9.7 μm silicate feature. We also compare the nuclear and integrated spectra. We find that the star formation takes place in extended regions (several kpc) as probed by the PAH emission, as well as the [Ne II]12.81 μm and [Ne III]15.56 μm emissions. The behavior of the integrated PAH emission and 9.7 μm silicate feature is similar to that of local starburst galaxies. We also find that the minima of the [Ne III]15.56 μm/[Ne II]12.81 μm ratio tends to be located at the nuclei and its value is lower than that of H II regions in our LIRGs and nearby galaxies. It is likely that increased densities in the nuclei of LIRGs are responsible for the smaller nuclear [Ne III]15.56 μm/[Ne II]12.81 μm ratios. This includes the possibility that some of the most massive stars in the nuclei are still embedded in ultracompact H II regions. In a large fraction of our sample, the 11.3 μm PAH emission appears more extended than the dust 5.5 μm continuum emission. We find a dependency of the 11.3 μm PAH/7.7 μm PAH and [Ne II]12.81 μm/11.3 μm PAH ratios with the age of the stellar populations. Smaller and larger ratios, respectively, indicate recent star formation. The estimated warm (300 K

Local luminous infrared galaxies: Spatially resolved mid-infrared observations with Spitzer/IRS

Luminous Infrared (IR) Galaxies (LIRGs, L_IR=10^11-10 L_⨀) are an important cosmological class of galaxies as they are the main contributors to the co-moving star formation rate density of the universe at z=1. In this paper we present a guaranteed time observation (GTO) Spitzer InfraRed Spectrograph (IRS) program aimed to obtain spectral mapping of a sample of 14 local d<76Mpc LIRGs. The data cubes map, at least, the central 20arcsec X 20arcsec to 30 arcsec X 30 arcsec regions of the galaxies, and use all four IRS modules covering the full 5-38 μ m spectral range. The final goal of this project is to characterize fully the mid-IR properties of local LIRGs as a first step to understanding their more distant counterparts. In this paper we present the first results of this GTO program. The IRS spectral mapping data allow us to build spectral maps of the bright mid-IR emission lines (e.g., [Ne II] 12.81 μ m, [Ne III]15.56 μ m, [S III] 18.71 μ m, H_2 at 17 μ m), continuum, the 6.2 and 11.3 μ m polycyclic aromatic hydrocarbon (PAH) features, and the 9.7 μ m silicate feature, as well as to extract 1D spectra for regions of interest in each galaxy. The IRS data are used to obtain spatially resolved measurements of the extinction using the 9.7 μ m silicate feature, and to trace star forming regions using the neon lines and the PAH features. We also investigate a number of active galactic nuclei (AGN) indicators, including the presence of high excitation emission lines and a strong dust continuum emission at around 6 9.7 μ m . We finally use the integrated Spitzer/IRS spectra as templates of local LIRGs. We discuss several possible uses for these templates, including the calibration of the star formation rate of IR-bright galaxies at high redshift. We also predict the intensities of the brightest mid-IR emission lines for LIRGs as a function of redshift, and compare them with the expected sensitivities of future space IR missions.

On the metallicity dependence of the 24 μm luminosity as a star formation tracer

We investigate the use of the rest-frame 24 μm luminosity as an indicator of the star formation rate (SFR) in galaxies with different metallicities by comparing it to the (extinction-corrected) Hα luminosity. We carry out this analysis in two steps: First, we compare the emission from H (II) regions in different galaxies with metallicities between 12 + and 8.9. We find that the 24 μm and the extinction-corrected Hα luminosities from individual H (II) log (O/H) = 8.1 regions follow the same correlation for all galaxies, independent of their metallicity. Second, the role of metallicity is explored further for the integrated luminosity in a sample of galaxies with metallicities in the range of 12 +. For this sample we compare the 24 μm and Hα luminosities integrated over the entire galaxies log (O/ H) = 7.2-9.1 and find a lack of the 24 μm emission for a given Hα luminosity for low-metallicity objects, likely reflecting a low dust content. These results suggest that the 24 μm luminosity is a good metallicity-independent tracer for the SFR in individual H (II) regions. On the other hand, metallicity has to be taken into account when using the 24 μm luminosity as a tracer for the SFR of entire galaxies.

Practical engineering of hard spin-glass instances

Recent technological developments in the field of experimental quantum annealing have made prototypical annealing optimizers with hundreds of qubits commercially available. The experimental demonstration of a quantum speedup for optimization problems has since then become a coveted, albeit elusive goal. Recent studies have shown that the so far inconclusive results, regarding a quantum enhancement, may have been partly due to the benchmark problems used being unsuitable. In particular, these problems had inherently too simple a structure, allowing for both traditional resources and quantum annealers to solve them with no special efforts. The need therefore has arisen for the generation of harder benchmarks which would hopefully possess the discriminative power to separate classical scaling of performance with size from quantum. We introduce here a practical technique for the engineering of extremely hard spin-glass Ising-type problem instances that does not require "cherry picking" from large ensembles of randomly generated instances. We accomplish this by treating the generation of hard optimization problems itself as an optimization problem, for which we offer a heuristic algorithm that solves it. We demonstrate the genuine thermal hardness of our generated instances by examining them thermodynamically and analyzing their energy landscapes, as well as by testing the performance of various state-of-the-art algorithms on them. We argue that a proper characterization of the generated instances offers a practical, efficient way to properly benchmark experimental quantum annealers, as well as any other optimization algorithm.

Universal critical behavior of the two-dimensional Ising spin glass

We use finite size scaling to study Ising spin glasses in two spatial dimensions. The issue of universality is addressed by comparing discrete and continuous probability distributions for the quenched random couplings. The sophisticated temperature dependency of the scaling fields is identified as the major obstacle that has impeded a complete analysis. Once temperature is relinquished in favor of the correlation length as the basic variable, we obtain a reliable estimation of the anomalous dimension and of the thermal critical exponent. Universality among binary and Gaussian couplings is confirmed to a high numerical accuracy.

Efficient numerical methods for the random-field Ising model: Finite-size scaling, reweighting extrapolation, and computation of response functions

It was recently shown [Phys. Rev. Lett. 110, 227201 (2013)] that the critical behavior of the random-field Ising model in three dimensions is ruled by a single universality class. This conclusion was reached only after a proper taming of the large scaling corrections of the model by applying a combined approach of various techniques, coming from the zero-and positive-temperature toolboxes of statistical physics. In the present contribution we provide a detailed description of this combined scheme, explaining in detail the zero-temperature numerical scheme and developing the generalized fluctuation-dissipation formula that allowed us to compute connected and disconnected correlation functions of the model. We discuss the error evolution of our method and we illustrate the infinite limit-size extrapolation of several observables within phenomenological renormalization. We present an extension of the quotients method that allows us to obtain estimates of the critical exponent a of the specific heat of the model via the scaling of the bond energy and we discuss the self-averaging properties of the system and the algorithmic aspects of the maximum-flow algorithm used.