Modeling of ore-forming and geoenvironmental systems: Roles of fluid flow and chemical reaction processes

Ore-forming and geoenviromental systems commonly involve coupled fluid flowand chemical reaction processes. The advanced numerical methods and computational modeling have become indispensable tools for simulating such processes in recent years. This enables many hitherto unsolvable geoscience problems to be addressed using numerical methods and computational modeling approaches. For example, computational modeling has been successfully used to solve ore-forming and mine site contamination/remediation problems, in which fluid flow and geochemical processes play important roles in the controlling dynamic mechanisms. The main purpose of this paper is to present a generalized overview of: (1) the various classes and models associated with fluid flow/chemically reacting systems in order to highlight possible opportunities and developments for the future; (2) some more general issues that need attention in the development of computational models and codes for simulating ore-forming and geoenviromental systems; (3) the related progresses achieved on the geochemical modeling over the past 50 years or so; (4) the general methodology for modeling of oreforming and geoenvironmental systems; and (5) the future development directions associated with modeling of ore-forming and geoenviromental systems.

Who seeks career counselling? A prospective study of personality and career variables among Swiss adolescents

This study investigated whether career adaptability, personality, attitude towards career counselling and some demographic variables predict the help seeking behaviour in career counselling among 330 Swiss adolescents in eighth grade. The results indicated that boys were less likely to seek help and that career related variables and attitude but not personality significantly predicted help-seeking. Specifically, help seeking related positively to undecidedness and positive perception of career counselling. Implications for school and career counsellors and suggestions for future research are presented.

A 4,103 marker integrated physical and comparative map of the horse genome

A comprehensive second-generation whole genome radiation hybrid (RH II), cytogenetic and comparative map of the horse genome (2n = 64) has been developed using the 5000rad horse x hamster radiation hybrid panel and fluorescence in situ hybridization (FISH). The map contains 4,103 markers (3,816 RH; 1,144 FISH) assigned to all 31 pairs of autosomes and the X chromosome. The RH maps of individual chromosomes are anchored and oriented using 857 cytogenetic markers. The overall resolution of the map is one marker per 775 kilobase pairs (kb), which represents a more than five-fold improvement over the first-generation map. The RH II incorporates 920 markers shared jointly with the two recently reported meiotic maps. Consequently the two maps were aligned with the RH II maps of individual autosomes and the X chromosome. Additionally, a comparative map of the horse genome was generated by connecting 1,904 loci on the horse map with genome sequences available for eight diverse vertebrates to highlight regions of evolutionarily conserved syntenies, linkages, and chromosomal breakpoints. The integrated map thus obtained presents the most comprehensive information on the physical and comparative organization of the equine genome and will assist future assemblies of whole genome BAC fingerprint maps and the genome sequence. It will also serve as a tool to identify genes governing health, disease and performance traits in horses and assist us in understanding the evolution of the equine genome in relation to other species.

Time variability and heterogeneity in the coma of 67P/Churyumov-Gerasimenko

Comets contain the best-preserved material from the beginning of our planetary system. Their nuclei and comae composition reveal clues about physical and chemical conditions during the early solar system when comets formed. ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) onboard the Rosetta spacecraft has measured the coma composition of comet 67P/Churyumov-Gerasimenko with well-sampled time resolution per rotation. Measurements were made over many comet rotation periods and a wide range of latitudes. These measurements show large fluctuations in composition in a heterogeneous coma that has diurnal and possibly seasonal variations in the major outgassing species: water, carbon monoxide, and carbon dioxide. These results indicate a complex coma-nucleus relationship where seasonal variations may be driven by temperature differences just below the comet surface.

Shifts in microbial communities do not explain the response of grassland ecosystem function to plant functional composition and rainfall change

Ecosystem functioning in grasslands is regulated by a range of biotic and abiotic factors, and the role of microbial communities in regulating ecosystem function has been the subject of much recent scrutiny. However, there are still knowledge gaps regarding the impacts of rainfall and vegetation change upon microbial communities and the implications of these changes for ecosystem functioning. We investigated this issue using data from an experimental mesotrophic grassland study in south-east England, which had been subjected to four years of rainfall and plant functional composition manipulations. Soil respiration, nitrogen and phosphorus stocks were measured, and the abundance and community structure of soil microbes were characterised using quantitative PCR and multiplex-TRFLP analysis, respectively. Bacterial community structure was strongly related to the plant functional composition treatments, but not the rainfall treatment. However, there was a strong effect of both rainfall change and plant functional group upon bacterial abundance. There was also a weak interactive effect of the two treatments upon fungal community structure, although fungal abundance was not affected by either treatment. Next, we used a statistical approach to assess whether treatment effects on ecosystem function were regulated by the microbial community. Our results revealed that ecosystem function was influenced by the experimental treatments, but was not related to associated changes to the microbial community. Overall, these results indicate that changes in fungal and bacterial community structure and abundance play a relatively minor role in determining grassland ecosystem function responses to precipitation and plant functional composition change, and that direct effects on soil physical and chemical properties and upon plant and microbial physiology may play a more important role.

Sulfur Isotopic Ratios at 67P/Churyumov-Gerasimenko and Characterization of ROSINA-DFMS FM & FS

Comets are thought to be the most pristine bodies present in the Solar System. In consequence of spending the majority of their existence beyond 30 AU, their composition can give insights on the physical and chemical conditions during their formation. Since August 2014 the European Space Agency spacecraft Rosetta accompanies the Jupiter family comet 67P/Churyumov-Gerasimenko on its way to perihelion and beyond. In this study the isotope fractionation of 34S are reported in H2S, OCS, SO2, S2, and CS2 at 67P. In addition for the first time the isotope fractionation for 33S is presented for cometary volatiles. The ratio 32S/33S is given for H2S, SO2 and a tentative value is given for CS2. With a mean value of -50 ± 22‰ and -306 ± 31‰ for δ34S and δ33S respectively, H2S shows a significant depletion in both 34S and 33S. For SO2 the depletion is less distinct with δ34S and δ33S being -67 ± 40‰ and -130 ± 53‰, respectively. The strongest depletion is present for CS2 with -114 ± 21‰and -276 ± 55‰, respectively. For OCS and S2 only δ34S could be determined which is -252 ± 77‰ and -357 ± 145‰, respectively. A comparison with sulfur isotopic ratios measured in SiC grains revealed that both SiC grains and the five volatile species have similar sulfur isotopic ratios. However, it is beyond the scope of this work to investigate the possibility of a link between SiC grains and cometary ices. Nevertheless, mass-dependent or mass-independent fractionation due to photo dissociation can be ruled out as sole cause of the seen depletion of 33S and 34S. Furthermore, an upper limit of (9.64 ± 0.19)·10.4 for D/H in HDS has been determined. This value is about a factor two higher than D/H in H2O for the same comet reported by (Altwegg et al., 2015). Besides the investigation concerning isotopic ratios of sulfur bearing species in this work the calibration and characterization of ROSINA/DFMS has been continued. Here it is reported about the deviation of the mass scale for MCP/LEDA low resolution spectra and the calibration measurements performed in the laboratory. Furthermore the outcome of the attempt to describe the sensitivity of DFMS with an empirical function will be discussed. The last part of the characterization of DFMS is dedicated to determine the so-called individual pixel gain for the laboratory and the flight model. Moreover, correlation between the depletion’s manifestation of the MCP with respect to the applied voltages has been investigated for both models. It has been found that further measurements are needed to understand the manifestation of depletion at the laboratory model. For the model on board of Rosetta it could be shown that most of the present feature are due to the usage of the MCP and suggestions have been made in order to answer the remaining question considering the depletion of the MCP.

Desiccation of phyllosilicate-bearing samples as analog for desiccation cracks on Mars: Experimental setup and initial results

The surface of Mars is host to many regions displaying polygonal crack patterns that have been identified as potential desiccation cracks. These regions are mostly within Noachian-aged terrains and are closely associated with phyllosilicate occurrences and smectites in particular. We have built a laboratory setup that allows us to carry out desiccation experiments on Mars-analog materials in an effort to constrain the physical and chemical properties of sediments that display polygonal cracks. The setup is complemented by a pre-existing simulation chamber that enables the investigation of the spectral and photometric properties of analog materials in Mars-like conditions. The initial experiments that have been carried out show that (1) crack patterns are visible in smectite-bearing materials in varying concentrations down to similar to 10% smectite by weight, (2) chlorides, and potentially other salts, delay the onset of cracking and may even block it from occurring entirely, and (3) the polygonal patterns, while being indicative of the presence of phyllosilicates, cannot be used to differentiate between various phyllosilicate-bearing deposits. However, their size-scale and morphology yields important information regarding their thickness and the hydrological conditions at the time of formation. Furthermore, the complementary spectral measurements for some of the analog samples shows that crack patterns may develop in materials with such low concentrations of smectites that would not be expected to be identified using remote-sensing instruments. This may explain the presence of polygonal patterns on Mars in sediments that lack spectral confirmation of phyllosilicates. (C) 2015 Elsevier Ltd. All rights reserved.

Physical and Biological Controls on the Latitudinal Asymmetry of Surface Nutrients and pCO(2) in the Central and Eastern Equatorial Pacific

Surface nutrients and dissolved inorganic carbon (DIC) in the central (CEP) and eastern equatorial Pacific (EEP) show much higher concentrations to the south than to the north of the equator. In this study, the physical and biological controls on this asymmetry are investigated using a coupled physical-biogeochemical model. Two numerical experiments are conducted to examine the effects of asymmetrical photosynthetic efficiency (a) due to asymmetrical iron supply about the equator. The experiment with asymmetrical photosynthesis produces improved results as compared with historical observations. A nitrate budget analysis suggests that in the EEP the divergence of upwelling waters controls the surface nitrate asymmetry with additional contribution from the South Equatorial Current (SEC) carrying nutrient-rich Peru upwelling water. The changes of a affect the surface nitrate distribution but not the overall asymmetry. The SEC further carries excess nitrate to the west and thus extends the asymmetry in the east to the CEP. In the CEP, however, stronger northward than southward transport tends to reduce the nitrate asymmetry, while the asymmetrical photosynthesis would help to maintain it. Similar processes also control the distributions of surface silicate and DIC in the equatorial Pacific, which is also affected by the air-sea CO(2) exchange. The asymmetrical photosynthesis influences the distribution of surface DIC, pCO(2), and the air-sea CO(2) flux, by redistributing about 20% CO(2) flux from the north to the south of the equator. Owing to the adjustment of air-sea CO(2) flux, however, the net surface DIC change is smaller than the direct change associated with primary production.

Physical and functional mapping of a novel tumor suppressor locus for prostate cancer within chromosome 10p12.31-q11

Prostate cancer remains the second leading cause of male cancer deaths in the United States, yet the molecular mechanisms underlying this disease remain largely unknown. Cytogenetic and molecular analyses of prostate tumors suggest a consistent association with the loss of chromosome 10. Previously, we have defined a novel tumor suppressor locus PAC-1 within chromosome 10pter-q11. Introduction of the short arm of chromosome 10 into a prostatic adenocarcinoma cell line PC-3H resulted in dramatic tumor suppression and restoration of a programmed cell death pathway. Using a combined approach of comparative genomic hybridization and microsatellite analysis of PC-3H, I have identified a region of hemizygosity within 10p12-p15. This region has been shown to be involved in frequent loss of heterozygosity in gliomas and melanoma. To functionally dissect the region within chromosome 10p containing PAC-1, we developed a strategy of serial microcell fusion, a technique that allows the transfer of defined fragments of chromosome 10p into PC-3H. Serial microcell fusion was used to transfer defined 10p fragments into a mouse A9 fibrosarcoma cell line. Once characterized by FISH and microsatellite analyses, the 10p fragments were subsequently transferred into PC-3H to generate a panel of microcell hybrid clones containing overlapping deletions of chromosome 10p. In vivo and microsatellite analyses of these PC hybrids identified a small chromosome 10p fragment (an estimated 31 Mb in size inclusive of the centromere) that when transferred into the PC-3H background, resulted in significant tumor suppression and limited a region of functional tumor suppressor activity to chromosome 10p12.31-q11. This region coincides with a region of LOH demonstrated in prostate cancer. These studies demonstrate the utility of this approach as a powerful tool to limit regions of functional tumor suppressor activity. Furthermore, these data used in conjunction with data generated by the Human Genome Project lent a focused approach to identify candidate tumor suppressor genes involved in prostate cancer. ^