1,575 research outputs found

    Assessing the role of tectono-magmatic setting in the precious metal (Au, Ag, PGE) and critical metal (Te, Se, Bi) endowment of Porphyry Cu deposits

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    Porphyry Cu deposits commonly contain critical and precious metal by-products, including the chalcophile and siderophile elements, Au, Pd, Pt, Ag, Te, Se, and Bi. These elements partition into residual sulfides during the partial melting of mantle wedge peridotite during subduction, potentially depleting the source magma for subduction-related porphyry Cu deposits. The chalcophile-rich residual sulfides in subduction-modified sub-continental lithosphere are thought to be the source of metals in postsubduction porphyry Cu deposits, and as such these deposits may be more enriched in chalcophile and siderophile elements than subduction-related porphyry deposits, although many postsubduction deposits have low Au grades. We test this by presenting whole-rock assay and PGE data with in situ LA-ICP-MS trace element data from sulfide minerals from three porphyry Cu deposits. The Skouries Cu-Au-(PGE) porphyry deposit, Greece, and the Muratdere Cu-Au-Mo porphyry deposit, Turkey are both postsubduction; these are contrasted with the El Teniente Cu-Mo porphyry deposit, Chile, which is a classic subduction-related system. By comparing these results with a newly compiled global dataset of trace element concentrations in sulfides from 18 other porphyry Cu deposits we show that postsubduction porphyry Cu deposit sulfides are relatively enriched in Bi, Sb, Te, and Se compared to sulfide minerals from subduction-related deposits. However, although some critical and precious metals (Ag, Bi, and Se) mainly reside in primary sulfide ore minerals, others (Au, Te, Pd, and Pt) are predominantly hosted in minor accessory minerals. Whole-rock data from mineralized samples show that although the Skouries and Muratdere deposits are enriched in Au compared with El Teniente, globally both subduction-related and postsubduction deposits can be precious and critical metal enriched, with metal endowment independent of tectonic setting. PGE-enriched porphyry Cu deposits are also enriched in Bi, Te, and Au, and semimetal melts are suggested to play an important role in PGE transport and concentration in porphyry Cu deposits

    Autonomous Speed Control for KIA Optima

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    The standard method for speed control is the cruise control system built into most modern vehicles. These systems employ a PID controller which actuates the accelerator thus, in turn, maintains the desired vehicle speed. The main drawback of such a system is that typically the cruise control will only engage above 25 mph. The goal of this paper is to describe a system which we used to control vehicle speed from a stop to any desired speed using an Arduino microcontroller and a CAN BUS shield, from where autonomous features can be built upon. With this system, we were able to implement a proportional gain controller which maintains the speed at within ±1 mph with a 1s rise time

    Assessment and monitoring of marine debris in Gray's Reef National Marine Sanctuary

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    Gray’s Reef National Marine Sanctuary (GRNMS) is located 32.4 km offshore of Sapelo Island, Georgia. The ecological importance of this area is related to the transition between tropical and temperate waters, and the existence of a topographically complex system of ledges. Due to its central location, GRNMS can be used as a focal site to study the accumulation and impacts of marine debris on the Atlantic continental shelf offshore of the Southeast United States. Previously, researchers characterized marine debris in GRNMS and reported that incidence of the debris at the limited densely colonized ledge sites was significantly greater than at sand or sparsely colonized live bottom, and is further influenced by the level of boating activity and physiographic characteristics (e.g., ledge height). Information gleaned from the initial marine debris characterization was used to devise a strategy for prioritizing cleanup and monitoring efforts. However, a significant gap in knowledge was the rate of debris accumulation. The primary objective of this study was to select, mark, and perform initial marine debris surveys at permanent monitoring sites within GRNMS to quantify long-term trends in types, abundance, impacts, and accumulation rates of debris. Ledge sites were selected to compare types, abundance, and accumulation rates of marine debris between a) areas of high and low use and b) short and tall ledges. Nine permanent monitoring sites were marked and initially surveyed in 2007/2008. Surveys were conducted within a 50 x 4 m transect for a total survey area of 200 square meters. All debris was removed and detailed information was taken on the types of debris, quantity, and associations with benthic fauna. Information on associations with benthic fauna included degree of entanglement, type of organism with which it is entangled or resting on, degree of fouling, and visible impacts such as tissue abrasions. Sites were re-surveyed approximately one year later to quantify new accumulation. During the initial survey, a total of ten debris items, totaling 16.3 kg in weight, were removed from two monitoring stations, both “tall” sites within the area of high boat use. Year-one accumulation totaled five items and approximately 7 kg in weight. Similar to the initial survey, all debris was found at sites in the area of high boat use. However, in contrast to the initial survey, two of these items were found on medium-height ledges. Removed items included fishing line, leaders, rope, plastic, and fabric. Although items were often encrusted in benthic biota or entangled on the ledge, impacts such as abrasions or other injuries were not observed. During the 2009 monitoring efforts, volunteer divers were trained to conduct the survey. Monitoring protocols were documented for GRNMS staff and included as an appendix of this report to enable long-term monitoring of sites. Additionally, national reconnaissance data (e.g. satellite, radar, aerial surveys) and other information on known fishing locations were examined for patterns of resource use and correlations with debris occurrence patterns. A previous model predicting the density of marine debris based on ledge features and boat use was refined and the results were used to generate a map of predicted debris density for all ledges

    Particle Removal by Electrostatic and Dielectrophoretic Forces for Dust Control During Lunar Exploration Missions

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    Particle removal during lunar exploration activities is of prime importance for the success of robotic and human exploration of the moon. We report on our efforts to use electrostatic and dielectrophoretic forces to develop a dust removal technology that prevents the accumulation of dust on solar panels and removes dust adhering to those surfaces. Testing of several prototypes showed solar shield output above 90% of the initial potentials after dust clearing

    WP 2015-331

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    Population aging and attendant pressures on public budgets have spurred considerable interest in understanding factors that influence retirement timing. A range of sociodemographic and economic characteristics have been shown to predict both earlier and later retirement. Less is known about the role of occupations and their characteristics on the work choices of older workers. Knowing more about the occupations that workers seem to stay in longer or leave earlier may point the way to policy interventions that are beneficial to both individuals and system finances. This project uses detailed occupational categories and work characteristics in the Health and Retirement Study (HRS) linked to information in the Occupational Information Network (O*NET) to examine compositional changes in occupations held by older workers over time; to provide some basic and interesting information about relationships between occupations and their characteristics and retirement expectations and outcomes; and to shed some light on which occupations and associated characteristics might encourage or discourage longer working lives. There are large percentage changes (increases in decreases) in the percentage of older workers in occupations over time. Considering detailed as opposed to aggregated occupational categories yields interesting additional information. Jobs that HRS respondents say entail less physical effort, less stress, and jobs that have not increased in difficulty in recent decades, and those in which people can reduce hours if desired, are associated with longer work. While the traditional blue collar-retire earlier and white collar-work longer associations emerge, we find interesting exceptions that suggest fruitful directions for future research.Social Security Administration5 RRC08098401-07http://deepblue.lib.umich.edu/bitstream/2027.42/117396/1/wp331.pd

    The Drosophila melanogaster gut microbiota provisions thiamine to its host

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    The microbiota of Drosophila melanogaster has a substantial impact on host physiology and nutrition. Some effects may involve vitamin provisioning, but the relationships between microbe-derived vitamins, diet, and host health remain to be established systematically. We explored the contribution of microbiota in supplying sufficient dietary thiamine (vitamin B1) to support D. melanogaster at different stages of its life cycle. Using chemically defined diets with different levels of available thiamine, we found that the interaction of thiamine concentration and microbiota did not affect the longevity of adult D. melanogaster Likewise, this interplay did not have an impact on egg production. However, we determined that thiamine availability has a large impact on offspring development, as axenic offspring were unable to develop on a thiamine-free diet. Offspring survived on the diet only when the microbiota was present or added back, demonstrating that the microbiota was able to provide enough thiamine to support host development. Through gnotobiotic studies, we determined that Acetobacter pomorum, a common member of the microbiota, was able to rescue development of larvae raised on the no-thiamine diet. Further, it was the only microbiota member that produced measurable amounts of thiamine when grown on the thiamine-free fly medium. Its close relative Acetobacter pasteurianus also rescued larvae; however, a thiamine auxotrophic mutant strain was unable to support larval growth and development. The results demonstrate that the D. melanogaster microbiota functions to provision thiamine to its host in a low-thiamine environment. Importance: There has been a long-standing assumption that the microbiota of animals provides their hosts with essential B vitamins; however, there is not a wealth of empirical evidence supporting this idea, especially for vitamin B1 (thiamine). To determine whether this assumption is true, we used Drosophila melanogaster and chemically defined diets with different thiamine concentrations as a model. We found that the microbiota does provide thiamine to its host, enough to allow the development of flies on a thiamine-free diet. The power of the Drosophila-microbiota system allowed us to determine that one microbiota member in particular, Acetobacter pomorum, is responsible for the thiamine provisioning. Thereby, our study verifies this long-standing hypothesis. Finally, the methods used in this work are applicable for interrogating the underpinnings of other aspects of the tripartite interaction between diet, host, and microbiota

    In Vitro Culture of the Insect Endosymbiont Spiroplasma poulsonii Highlights Bacterial Genes Involved in Host- Symbiont Interaction

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    Endosymbiotic bacteria associated with eukaryotic hosts are omnipresent in nature, particularly in insects. Studying the bacterial side of host-symbiont interactions is, however, often limited by the unculturability and genetic intractability of the symbionts. <i>Spiroplasma poulsonii</i> is a maternally transmitted bacterial endosymbiont that is naturally associated with several <i>Drosophila</i> species. <i>S. poulsonii</i> strongly affects its host's physiology, for example by causing male killing or by protecting it against various parasites. Despite intense work on this model since the 1950s, attempts to cultivate endosymbiotic <i>Spiroplasma in vitro</i> have failed so far. Here, we developed a method to sustain the <i>in vitro</i> culture of <i>S. poulsonii</i> by optimizing a commercially accessible medium. We also provide a complete genome assembly, including the first sequence of a natural plasmid of an endosymbiotic <i>Spiroplasma</i> species. Last, by comparing the transcriptome of the <i>in vitro</i> culture to the transcriptome of bacteria extracted from the host, we identified genes putatively involved in host-symbiont interactions. This work provides new opportunities to study the physiology of endosymbiotic <i>Spiroplasma</i> and paves the way to dissect insect-endosymbiont interactions with two genetically tractable partners. <b>IMPORTANCE</b> The discovery of insect bacterial endosymbionts (maternally transmitted bacteria) has revolutionized the study of insects, suggesting novel strategies for their control. Most endosymbionts are strongly dependent on their host to survive, making them uncultivable in artificial systems and genetically intractable. <i>Spiroplasma poulsonii</i> is an endosymbiont of <i>Drosophila</i> that affects host metabolism, reproduction, and defense against parasites. By providing the first reliable culture medium that allows a long-lasting <i>in vitro</i> culture of <i>Spiroplasma</i> and by elucidating its complete genome, this work lays the foundation for the development of genetic engineering tools to dissect endosymbiosis with two partners amenable to molecular study. Furthermore, the optimization method that we describe can be used on other yet uncultivable symbionts, opening new technical opportunities in the field of host-microbes interactions

    Pennsylvania Folklife Vol. 16, No. 3

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    • Reminiscences of a Boyhood in Reading, 1883-1890 • Preserving York\u27s Architectural Heritage • Jordan Museum of the Twenty • Pennsylvania Broadsides: II • Memoirs of a Lutheran Minister, 1850-1881 • Notes and Documents: Nicknames from a Mennonite Family • The Crafts at Newport • Anglicizing the Pennsylvania Dutch, 1966 and 1875 • Nicknames: Folk-Cultural Questionnaire #3https://digitalcommons.ursinus.edu/pafolklifemag/1027/thumbnail.jp

    Financial phantasmagoria: corporate image-work in times of crisis

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    Our purpose in this article is to relate the real movements in the economy during 2008 to the ?image-work? of financial institutions. Over the period January?December 2008 we collected 241 separate advertisements from 61 financial institutions published in the Financial Times. Reading across the ensemble of advertisements for themes and evocative images provides an impression of the financial imaginaries created by these organizations as the global financial crisis unfolded. In using the term ?phantasmagoria? we move beyond its colloquial sense of a set of strange images designed to dazzle towards the more technical connotation used by Ranci�re (2004) who suggested that words and images can offer a trace of an overall determining set-up if they are torn from their obviousness so they become phantasmagoric figures. The key phantasmagoric figure we identify here is that of the financial institution as timeless, immortal and unchanging; a coherent and autonomous entity amongst other actors. This notion of uniqueness belies the commonality of thinking which precipitated the global financial crisis as well as the limited capacity for control of financial institutions in relation to market events. It also functions as a powerful naturalizing force, making it hard to question certain aspects of the recent period of ?capitalism in crisis?
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