Exploration potential of Cu isotope fractionation in porphyry copper deposits   总被引：6，自引：0，他引：6  

Ryan Mathur  Spencer TitleyFernando Barra  Susan BrantleyMarc Wilson  Allison PhillipsFrancisco Munizaga  Victor MaksaevJeff Vervoort  Garret Hart 《Journal of Geochemical Exploration》2009

We examined the copper isotope ratio of primary high temperature Cu-sulfides, secondary low temperature Cu-sulfides (and Cu-oxides) as well as Fe-oxides in the leach cap, which represent the weathered remains of a spectrum of Cu mineralization, from nine porphyry copper deposits. Copper isotope ratios are reported as δ⁶⁵Cu‰ = ((⁶⁵Cu/⁶³Cu_sample/⁶⁵Cu/⁶³Cu_{NIST 976 standard}) − 1) ? 10³. Errors for all the analyses are ± 0.14‰ (determined by multiple analyses of the samples) and mass bias was corrected through standard-sample-standard bracketing. The overall isotopic variability measured in these samples range from − 16.96‰ to 9.98‰.  相似文献   

Narrow-line Seyfert 1 galaxies and the evolution of galaxies and active galaxies   总被引：1，自引：0，他引：1  

Smita Mathur 《Monthly notices of the Royal Astronomical Society》2000,314(4):L17-L20

Narrow Line Seyfert 1 galaxies (NLS1s) are intriguing owing to their continuum as well as emission-line properties. The observed peculiar properties of the NLS1s are believed to be as a result of an accretion rate close to the Eddington limit. As a consequence of this, for a given luminosity, NLS1s have smaller black hole (BH) masses compared with normal Seyfert galaxies. Here we argue that NLS1s might be Seyfert galaxies in their early stage of evolution and as such may be low-redshift, low-luminosity analogues of high-redshift quasars. We propose that NLS1s may reside in rejuvenated, gas-rich galaxies. We also argue in favour of collisional ionization for production of Fe  ii in active galactic nuclei.  相似文献   

Update on g‐mode research     

R.A. García  A. Jimnez  S. Mathur  J. Ballot  A. Eff‐Darwich  S. J. Jimnez‐Reyes  P. L. Pall  J. Provost  S. Turck‐Chize 《Astronomische Nachrichten》2008,329(5):476-484

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Can We Constrain Solar Interior Physics by Studying the Gravity-Mode Asymptotic Signature?     

R. A. García  S. Mathur  J. Ballot 《Solar physics》2008,251(1-2):135-147

Gravity modes are the best probes to infer the properties of the solar radiative zone, which represents 98% of the Sun’s total mass. It is usually assumed that high-frequency g modes give information about the structure of the solar interior whereas low-frequency g modes are more sensitive to the solar dynamics (the internal rotation). In this work, we develop a new methodology, based on the analysis of the almost constant separation of the dipole gravity modes, to introduce new constraints on the solar models. To validate this analysis procedure, several solar models – including different physical processes and either old or new chemical abundances (from, respectively, Grevesse and Noels (Origin and Evolution of the Elements 199, Cambridge University Press, Cambridge, 15, 1993) and Asplund, Grevesse, and Sauval (Cosmic Abundances as Records of Stellar Evolution and Nucleosynthesis CS-336, Astron. Soc. Pac., San Francisco, 25?–?38, 2005)) – have been compared to another model used as a reference. The analysis clearly shows that this methodology has enough sensitivity to distinguish among some of the models, in particular, among those with different compositions. The comparison of the models with the g-mode asymptotic signature detected in GOLF data favors the ones with old abundances. Therefore, the physics of the core – obtained through the analysis of the g-mode properties – is in agreement with the results obtained in the previous studies based on the acoustic modes, which are mostly sensitive to more external layers of the Sun.  相似文献   

IGCP-274: Coastal evolution in the quaternary     

U. B. Mathur 《Journal of the Indian Society of Remote Sensing》1989,17(2):67-67

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Preliminary pedogeochemical and biogeochemical studies on the Hinota kimberlite,Panna District,MP     

S M Mathur  P O Alexander 《Journal of Earth System Science》1983,92(1):81-97

Distribution of a number of trace elements in the Hinota kimberlite pipe, its overlying soil and selected vegetation is discussed in relation to the distribution of the same elements in the soils and vegetation overlying the quartzite country rock through which it is emplaced. The values of most elements in Hinota are similar to those of kimberlites from some other parts of the world, but Ni and Cu are higher. These elements in a “floating reef” of the Dhandraul Quartzite in the pipe closely follow the averages for other sandstones. It is observed that most elements in the soil over the kimberlite are significantly higher than in the soil over the surrounding country rock, particularly Ni, V, Cu and Cr. These could serve as reasonable guides to prospecting for kimberlites. Trace elements in the ash of selected trees growing over the diatreme and the country rock do not show any significant differences.  相似文献   

Acute Toxicity of Mercury,Copper and Zinc to a Freshwater Pulmonate Snail,Lymnaea luteola (LAMARCK)     

S. Mathur  B. S. Khangarot  V. R. Durve 《洁净——土壤、空气、水》1981,9(4):381-389

The short-term toxicity of mercury, copper and zinc was studied using a freshwater pulmonate snail, Lymnaea luteola (LAMARCK ). The median period of survival increases with decreasing the toxicant concentration. The 96 h LC₅₀ values and their confidence limits were 0.135 (0.112 … 0.186) ppm of Hg²⁺; 0.172 (0.118 … 0.355) ppm of Cu²⁺; and 6.13 (5.73 to 7.19) ppm of Zn²⁺. The relative potency ratio indicates that the Hg²⁺ ions were most toxic, followed by Cu²⁺ and Zn²⁺ ions.  相似文献   

A new scenario framework for climate change research: the concept of shared socioeconomic pathways   总被引：4，自引：1，他引：3  

Brian C. O’Neill  Elmar Kriegler  Keywan Riahi  Kristie L. Ebi  Stephane Hallegatte  Timothy R. Carter  Ritu Mathur  Detlef P. van Vuuren 《Climatic change》2014,122(3):387-400

The new scenario framework for climate change research envisions combining pathways of future radiative forcing and their associated climate changes with alternative pathways of socioeconomic development in order to carry out research on climate change impacts, adaptation, and mitigation. Here we propose a conceptual framework for how to define and develop a set of Shared Socioeconomic Pathways (SSPs) for use within the scenario framework. We define SSPs as reference pathways describing plausible alternative trends in the evolution of society and ecosystems over a century timescale, in the absence of climate change or climate policies. We introduce the concept of a space of challenges to adaptation and to mitigation that should be spanned by the SSPs, and discuss how particular trends in social, economic, and environmental development could be combined to produce such outcomes. A comparison to the narratives from the scenarios developed in the Special Report on Emissions Scenarios (SRES) illustrates how a starting point for developing SSPs can be defined. We suggest initial development of a set of basic SSPs that could then be extended to meet more specific purposes, and envision a process of application of basic and extended SSPs that would be iterative and potentially lead to modification of the original SSPs themselves.  相似文献   

Experiences of host communities with carbon market projects: towards multi-level climate justice     

Vivek N. Mathur  Stavros Afionis  Jouni Paavola  Andrew J. Dougill  Lindsay C. Stringer 《Climate Policy》2014,14(1):42-62

The literature on equity and justice in climate change mitigation has largely focused on North–South relations and equity between states. However, some initiatives (e.g. the Clean Development Mechanism (CDM), the Reducing Emissions from Deforestation and Forest Degradation programme (REDD), and voluntary carbon markets (VCMs)) are already establishing multi-level governance structures that involve communities from developing countries in global mitigation efforts. This poses new equity and justice dilemmas: how the burdens and benefits of mitigation are shared across various levels and how host communities are positioned in multi-level governance structures. A review of the existing literature is used to distill a framework for distinguishing between four axes of climate justice from the perspective of communities. Empirical evidence from African and Asian carbon market projects is used to assess the distributive and procedural justice implications for host communities. The evidence suggests that host communities often benefit little from carbon market projects and find it difficult to protect their interests. Capacity building, attention to local power relations, supervision of business practices, promotion of projects with primarily development aims and an active involvement of non-state actors as bridges between local communities and the national/international levels could potentially contribute towards addressing some of the key justice concerns.Policy relevance International negotiations on the institutional frameworks that are envisaged to govern carbon markets are proceeding at a rather slow pace. As a consequence, host countries and private-sector actors are making their own arrangements to safeguard the interests of local communities. While several standards have emerged to guide carbon market activity on the ground, distributive as well as procedural justice concerns nevertheless remain salient. Four empirical case studies across Asia and Africa show that within the multi-scale and multi-actor carbon market governance, local-level actors often lack sufficient agency to advance their claims and protect their interests. This evidence suggests that ameliorating policy reforms are needed to enhance the positioning of local communities. Doing so is important to ensure future acceptability of carbon market activity in potential host communities as well as for ensuring their broader legitimacy.  相似文献   

Laboratory performances of the solar multichannel resonant scattering spectrometer prototype of the GOLF‐New Generation instrument     

S. Turck‐Chize  P.H. Carton  S. Mathur  J.‐C. Barrire  P. Daniel‐Thomas  C. Lahonde‐Hamdoun  D. Loiseau  F. Nunio  Y. Piret  J.M. Robillot 《Astronomische Nachrichten》2008,329(5):521-528

This article quickly summarizes the performances and results of the GOLF/SoHO resonant spectrometer, thus justifying to go a step further. We then recall the characteristics of the multichannel resonant GOLF‐NG spectrometer and present the first successful performances of the laboratory tests on the prototype and also the limitations of this first technological instrument. Scientific questions and an observation strategy are discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献