Mineralogy, Isotope Geochemistry and Geothermometry of the Lowry Deposit, Black Butte Copper Project, Meagher County, Montana

The Black Butte Copper Project is a sedimentary rock hosted, Cu-rich massive sulfide deposit hosted in rocks of the ca. 1.5-1.325 Ga Mesoproterozoic Belt Supergroup. Copper-bearing sulfides, mainly chalcopyrite and tennantite, are hosted in debris flows, black shale, dolostone and sedimentary pyrite layers of the Newland Fm. of the Lower Belt Group in the Helena Embayment, an E-W striking limb of the greater NNW trending Belt Basin. Mineralization is hosted within two separate but contemporaneous deposits, Johnny Lee, which hosts Cu sulfides in an upper and lower sulfide zone within sedimentary pyrite and debris flow conglomerates, and Lowry, where Cu sulfides are hosted in a middle and lower sulfide zone in dolomite dissolution breccias and veins cutting the host Newland Fm. in addition to sedimentary pyrite and debris flows. Mineralization at Black Butte has many characteristics of sedimentary exhalative (sedex) type deposits- massive, laterally extensive pyrite hosted in black shales, accessory silver, formation within a continental rift, evidence of seafloor hydrothermal venting- but, unlike most sedex deposits, Black Butte is a Cu sulfide deposit that lacks Pb and Zn. Hence, the deposit model assigned to the Black Butte Project is a hybrid between sedex, based on the environment of ore formation, and stratabound sedimentary hosted Cu, based on the Cu dominant ore. This research aimed to apply robust and innovative geochemical methods to characterize the conditions of formation of the Lowry deposit. Sulfur stable isotope analysis of chalcopyrite from the Lowry deposit show a range of 34S between +/- 5‰ of zero. When plotted with other S isotopes of pyrite and chalcopyrite from the Black Butte Project, a broad range of S-isotope values in pyrite reflect bacterial reduction of marine sulfate (BSR), while the more restricted range in chalcopyrite can be explained by higher temperature thermochemical sulfate reduction (TSR). Carbonate isotopes from hydrothermal dolomite range from +16 to +22‰ in 18O and 0 to -5‰ in 13C, and are depleted in both 18O and 13C compared to sedimentary carbonate from the Newland Fm. Bitumen occurs in recrystallized dolomite and veins along with quartz, pyrite and chalcopyrite, and has reflectance and Raman spectroscopy values consistent with maximum mean temperatures of 223± 8°C (n=8) with a range of 212.8 – 239.5°C and 247± 40°C (n=7) with a range of 219 – 265°C respectively. Sr isotopes from Lowry and Johnny Lee dolomite reflect the modeled Sr values for Proterozoic seawater. Pb isotopes of Lowry sulfides and dolomite plot within an upper crustal source. These geochemical data, combined with observations of mineralized drill core through hand sample and microscopy, suggest that the Lowry deposit formed after deposition of the lower Newland Fm. at temperatures near or below 250°C. Limestone beds were altered to dolomite during diagenesis creating open space for hydrocarbon migration. High-temperature thermochemical sulfate reduction (TSR) replaced bacterial sulfate reduction (BSR) and altered hydrocarbons to bitumen and porewater sulfate to H2S, creating favorable depositional sites for metalliferous fluids. Fluids were sourced from connate brines circulating in the Helena Embayment of the Mesoproterozoic Belt-Purcell basin that scavenged metals from an underlying crustal source and deposited sulfides and gangue upon encountering favorable facies while migrating along structural pathways

Comparative Endocrinology of Aging and Longevity Regulation

Hormones regulate growth, development, metabolism, and other complex processes in multicellular animals. For many years it has been suggested that hormones may also influence the rate of the aging process. Aging is a multifactorial process that causes biological systems to break down and cease to function in adult organisms as time passes, eventually leading to death. The exact underlying causes of the aging process remain a topic for debate, and clues that may shed light on these causes are eagerly sought after. In the last two decades, gene mutations that result in delayed aging and extended longevity have been discovered, and many of the affected genes have been components of endocrine signaling pathways. In this review we summarize the current knowledge on the roles of endocrine signaling in the regulation of aging and longevity in various animals. We begin by discussing the notion that conserved systems, including endocrine signaling pathways, “regulate” the aging process. Findings from the major model organisms: worms, flies, and rodents, are then outlined. Unique lessons from studies of non-traditional models: bees, salmon, and naked mole rats, are also discussed. Finally, we summarize the endocrinology of aging in humans, including changes in hormone levels with age, and the involvement of hormones in aging-related diseases. The most well studied and widely conserved endocrine pathway that affects aging is the insulin/insulin-like growth factor system. Mutations in genes of this pathway increase the lifespan of worms, flies, and mice. Population genetic evidence also suggests this pathway’s involvement in human aging. Other hormones including steroids have been linked to aging only in a subset of the models studied. Because of the value of comparative studies, it is suggested that the aging field could benefit from adoption of additional model organisms

Influence diagrams : a new approach to modelling games

Game theory seeks to describe the interaction of two or more actors with distinct objectives. This is achieved using a mathematical model known as a game. Virtually all game theory relies on either the extensive form or the normal form to represent the games being studied. By drawing on the previously unrelated fields of game theory and graphical modelling, and by taking a new approach to the way in which a game is modelled, an alternative to the extensive and normal forms is developed: the belief influence diagram (BID). Starting from the basic definition of a game and using a new form of conditional belief called a prospective function, it is shown how the decision influence diagram can be adapted to model games. The advantages of the BID over the extensive and normal forms are explored, particularly its ability to model some of the qualitative aspects of games and to model games of greater complexity. By using BIDs in the modelling of games, fresh insight can be gained into certain features of the game, such as what sources of information an actor in the game should take account of. New concepts of sufficiency and parsimony are defined which relate to the BID. It is shown how these concepts, when combined with different forms of rationality, can lead to a variety of methods for simplifying a BID, and hence simplifying the game which it represents. It is shown that such simplifications arc invariant with respect to the order in which the simplifying steps are carried out. A schematic version of the BID is used to model finite repeated games and to develop concepts of learning and local sufficiency. It is shown how BIDs can be used to facilitate an induction proof in a finite repeated game and to model a highly complex competitive market. This last example is used to illustrate how BIDs can be helpful in evaluating some qualitative aspects of a model

A physically motivated and empirically calibrated method to measure effective temperature, metallicity, and Ti abundance of M dwarfs

The ability to perform detailed chemical analysis of Sun-like F-, G-, and K-type stars is a powerful tool with many applications including studying the chemical evolution of the Galaxy and constraining planet formation theories. Unfortunately, complications in modeling cooler stellar atmospheres hinders similar analysis of M-dwarf stars. Empirically-calibrated methods to measure M dwarf metallicity from moderate-resolution spectra are currently limited to measuring overall metallicity and rely on astrophysical abundance correlations in stellar populations. We present a new, empirical calibration of synthetic M dwarf spectra that can be used to infer effective temperature, Fe abundance, and Ti abundance. We obtained high-resolution (R~25,000), Y-band (~1 micron) spectra of 29 M dwarfs with NIRSPEC on Keck II. Using the PHOENIX stellar atmosphere modeling code (version 15.5), we generated a grid of synthetic spectra covering a range of temperatures, metallicities, and alpha-enhancements. From our observed and synthetic spectra, we measured the equivalent widths of multiple Fe I and Ti I lines and a temperature-sensitive index based on the FeH bandhead. We used abundances measured from widely-separated solar-type companions to empirically calibrate transformations to the observed indices and equivalent widths that force agreement with the models. Our calibration achieves precisions in Teff, [Fe/H], and [Ti/Fe] of 60 K, 0.1 dex, and 0.05 dex, respectively and is calibrated for 3200 K < Teff < 4100 K, -0.7 < [Fe/H] < +0.3, and -0.05 < [Ti/Fe] < +0.3. This work is a step toward detailed chemical analysis of M dwarfs at a similar precision achieved for FGK stars.Comment: accepted for publication in ApJ, all synthetic spectra available at http://people.bu.edu/mveyette/phoenix

Tumour necrosis factor-α stimulates dehydroepiandrosterone metabolism in human fibroblast-like synoviocytes: a role for nuclear factor-κB and activator protein-1 in the regulation of expression of cytochrome p450 enzyme 7b

Glucocorticoids have successfully been used in the treatment of rheumatoid arthritis. Data suggest that 7α-hydroxy-dehydroepiandrosterone (7α-OH-DHEA), an immunostimulating metabolite of dehydroepiandrosterone, can block glucocorticoid-induced immune suppression. Formation of 7α-OH-DHEA is catalyzed by activity of cytochrome p450 enzyme 7b (Cyp7b). Recently, we reported that tumour necrosis factor (TNF)-α, IL-1α, IL-1β and IL-17 enhance Cyp7b mRNA expression and induce a concomitant increase in the formation of 7α-OH-DHEA by fibroblast-like synoviocytes (FLS) from rheumatoid arthritis patients. The aim of this study was to elucidate which signal transduction pathway is involved in the TNF-α-mediated induction of Cyp7b activity in FLS. We studied the effects of inhibitors of different signal transduction pathways on Cyp7b activity in FLS by measuring Cyp7b mRNA expression using reverse transcription PCR and by measuring the formation of 7α-OH-DHEA. We applied SN50, an inhibitor of nuclear translocation of transcription factors (i.e. activator protein-1 [AP-1] and nuclear factor-κB [NF-κB]); PSI, a proteasome inhibitor that prevents IκB degradation and thereby NF-κB release; SP600125, a c-Jun N-terminal kinase (JNK) inhibitor; and the mitogen-activated protein kinase inhibitors PD98059 (extracellular signal-regulated kinase) and SB203580 (p38). Cyp7b is constitutively expressed in RA FLS and can be activated in response to TNF-α. SN50 and PSI prevented the TNF-α-induced increase in Cyp7b activity, whereas the mitogen-activated protein kinase inhibitors PD98059 and SB203580 had no effect. In addition, inhibition of Cyp7b mRNA expression and activity was observed with SN50, PSI and SP600125, suggesting that NF-κB and AP-1 induce Cyp7b transcription. These findings suggest that NF-κB and AP-1 are involved in the TNF-α-enhanced formation of the dehydroepiandrosterone metabolite 7α-OH-DHEA. Our results are in accordance with presence of AP-1 and NF-κB binding sites in the Cyp7b promoter

Predictive Peacekeeping: Strengthening Predictive Analysis in UN Peace Operations

The UN is becoming increasingly data-driven. Until recently, data-driven initiatives have mainly been led by individual UN field missions, but with António Guterres, the new Secretary-General, a more centralized approach is being embarked on. With a trend towards the use of data to support the work of UN staff, the UN is likely to soon rely on systematic data analysis to draw patterns from the information that is gathered in and across UN field missions. This paper is based on UN peacekeeping data from the Joint Mission Analysis Centre (JMAC) in Darfur, and draws on interviews conducted in New York, Mali and Sudan. It will explore the practical and ethical implications of systematic data analysis in UN field missions. Systematic data analysis can help the leadership of field missions to decide where to deploy troops to protect civilians, guide conflict prevention efforts and help preempt threats to the mission itself. However, predictive analysis in UN peace operations will only be beneficial if it also leads to early action. Finally, predictive peacekeeping will not only be demanding of resources, it will also include ethical challenges on issues such as data privacy and the risk of reidentification of informants or other potentially vulnerable people

LiHe spectra from brown dwarfs to helium clusters

International audienceThe detection of Li I lines is the most decisive spectral indicator of substellarity for young brown dwarfs with masses below about 0.06 solar mass. Due to the weakness of the Li resonance lines, it is important to be able to model precisely both their core widths and their wing profiles. This allows an adequate prediction of the mass at which Li lines reappear in the spectra of brown dwarfs for a given age, or reversely an accurate determination of the age of a cluster. We report improved line profiles and the dependence of line width on temperature suitable for modeling substellar atmospheres that were determined from new LiHe molecular potential energies. Over a limited range of density and temperature, comparison with laboratory measurements was used to validate the potential energies which support the spectral line profile theory

Facies model for a coarse-grained, tide-influenced delta : Gule Horn Formation (Early Jurassic), Jameson Land, Greenland

Acknowledgements: Funding for this project was provided from the Research Council of Norway through the Petromaks project 193059 and the FORCE Safari Project. Arild Andresen (University of Oslo) and Aka Lynge (POLOG) are thanked for logistical support, Björn Nyberg (Uni Research CIPR and University of Bergen) for assistance in the field, Arve Næss (Statoil) for providing data and assistance during the planning phase, Julien Vallet and Huges Fournier (Helimap Systems SA) for data acquisition. Riegl LMS GmbH is acknowledged for software support. We thank Brian Willis and an anonymous reviewer for their insightful and thorough reviews and Mariano Marzo for editorial comments.Peer reviewedPublisher PD

A Time-Dependent Radiative Model of HD209458b

We present a time-dependent radiative model of the atmosphere of HD209458b and investigate its thermal structure and chemical composition. In a first step, the stellar heating profile and radiative timescales were calculated under planet-averaged insolation conditions. We find that 99.99% of the incoming stellar flux has been absorbed before reaching the 7 bar level. Stellar photons cannot therefore penetrate deeply enough to explain the large radius of the planet. We derive a radiative time constant which increases with depth and reaches about 8 hr at 0.1 bar and 2.3 days at 1 bar. Time-dependent temperature profiles were also calculated, in the limit of a zonal wind that is independent on height (i.e. solid-body rotation) and constant absorption coefficients. We predict day-night variations of the effective temperature of \~600 K, for an equatorial rotation rate of 1 km/s, in good agreement with the predictions by Showman &Guillot (2002). This rotation rate yields day-to-night temperature variations in excess of 600 K above the 0.1-bar level. These variations rapidly decrease with depth below the 1-bar level and become negligible below the ~5--bar level for rotation rates of at least 0.5 km/s. At high altitudes (mbar pressures or less), the night temperatures are low enough to allow sodium to condense into Na2S. Synthetic transit spectra of the visible Na doublet show a much weaker sodium absorption on the morning limb than on the evening limb. The calculated dimming of the sodium feature during planetary transites agrees with the value reported by Charbonneau et al. (2002).Comment: 9 pages, 8 figures, replaced with the revised versio