202 research outputs found
THE ISOTOPIC SIGNATURE OF THE MINERALIZING FLUID OF THE LAVRION CARBONATE-REPLACEMENT PB-ZN-AG DISTRICT
The Pb-Zn-Ag carbonate-replacement deposits in the Lavrion district are genetically related to a 7- 10 Ma-old granodiorite, felsic dikes and sills. These deposits are hosted in the Upper and Lower marble and schists of the Cyclades Blueschist unit and occur along the major Legraina detachment fault. Carbonate-replacement orebodies occur as âmantosâ and veins, dominated by base metal sulfides and Ag, Bi, Sn, Sb, As, and Pb sulfosalts. Calculated carbon and oxygen isotope compositions of the hydrothermal fluid range from ÎŽ13CCO2 of -13.7 to 0.8 per mil and ÎŽ18OH2O of 4.2 to 27.4 per mil, at 400Âș, 350Âș, 320Âș, 300Âș, 250Âș and 200ÂșC. These isotopic compositions reveal water-torock ratios ranging from 4.8 to 52.6%, which reflect intense interaction of the ore fluid with the host rock in a water-dominated, transitional closed to open hydrothermal system. The range of ÎŽ34SH2S for sulfides in the deposits were from -8.5 to 6.8 per mil, for similar temperatures, whereas for barite-fluorite veins from ÎŽ34SH2S of -43.6 to -16.4 per mil, at 200Âș, 150Âș and 100ÂșC. This range implies that there was contribution from a magmatic sulfur component exsolved from the Plaka pluton, as well as contribution from a metasedimentary component. Based on the isotopic signature of sulfur for barite, the ranges from -6.7 to -7.6, comprising an increase in the fluid influx. Isotopic temperatures based on pyrite-galena and sphalerite-pyrite pairs revealed at least three major events of carbonate-replacement ore deposition, (i) at ~ 360Âș, (ii) 320Âș-280Âșand (iii) 260Âș-200ÂșC
Karakasi mines, Hermione, evolution of a Cyprus-type Cu-Zn deposit, Argolis, Greece
The Hermione Cyprus-type Cu-Zn deposits, Argolis, Greece, are hosted in Miocene ophiolites overlain by terrigenous turbidites with intercalations of limestones and manganiferous iron formations. The ore deposits form irregular lenticular or stratiform ore bodies, and veins. These ore bodies are associated with marginal volcanic activity in an arc-related Miocene palaeocontinent. Late N- to NNE-trending, sinistral, milky quartz-pyrite-calcite veins cut the host ophiolites. Alteration haloes of quartz-calcite, albite-sericite-chlorite, and chalcedony-epidote-clay minerals envelop the veins or develop in the lavas as concentric shells. The tellurium-bearing Cu-Zn mineralization is developed in two successive stages followed by a supergene stage. The Co-pyrite- chalcopyrite geothermometer defined two stages of sulphide equilibrium: 310° to 375°C (Stage I), and 220° to 260°C (Stage II). The calculated ÎŽ180 and \u3c5D compositions of the waters reflect the dominance of a magmatic component. The calculated ÎŽ3^Î^ fluid values also reveal a magmatic source for the sulphur, with minor contribution from submarine sediments, whereas tellurium is proposed to be derived from a mafic-ultramafic source. The physicochemical conditions of the hydrothermal fluids in the Hermione system were T=250°-300°C, P ~ 450 bars, pH =j61 to 530,fS2 HS aq) : = 10\u2711·6 to 10-12·4,fo2 = 10-35·5 to 10-38·3, logaH2S(aq) = 10\u273\u277 to 10\u2740, and loga = 10\u271 2·6 to 10-3·4
Surface albedo changes with time on Titanâs possible cryovolcanic sites: Cassini/VIMS processing and geophysical implications
We present a study on Titanâs possibly cryovolcanic and varying regions as suggested from previous studies [e.g. 1;2;7]. These regions, which are potentially subject to change over time in brightness and are located close to the equator, are Tui Regio, Hotei Regio, and Sotra Patera. We apply two methods on Cassini/VIMS data in order to retrieve their surface properties and monitor any temporal variations. First, we apply a statistical method, the Principal Component Analysis (PCA) [3;4] where we manage to isolate regions of distinct and diverse chemical composition called âRegion of interest â RoIâ. Then, we focus on retrieving the spectral differences (with respect to the Huygens landing site albedo) among the RoIs by applying a radiative transfer code (RT) [5;3]. Hence, we are able to view the dynamical range and evaluate the differences in surface albedo within the RoIs of the three regions. In addition, using this double procedure, we study the temporal surface variations of the three regions witnessing albedo changes with time for Tui Regio from 2005-2009 (darkening) and Sotra Patera from 2005-2006 (brightening) at all wavelengths [3]. The surface albedo variations and the presence of volcanic-like features within the regions in addition to a recent study [6] that calculates Titan's tidal response are significant indications for the connection of the interior with the cryovolcanic candidate features with implications for the satelliteâs astrobiological potential
The evolution of a W, Au-Ag-Te and Au-Ag hydrothermal system, Tinos Island, Cyclades, Greece
At Tinos Island, Greece, the physicochemical evolution of the hydrothermal system and the associated stages of metallic mineralization that are developed in the vicinity of the Tinos granodiorite-leucogranite has been studied, based on fluid inclusion studies and chemical reactions modeling. Early tungsten mineraliozation was related to the metasomatic stage of contact metamorphism and precipitated at ~ 350oC, from moderate saline (10.4 to 14.8 wt% NaCl eq.), CO2- effervescing fluids, that contained variable amounts of CaCl2 and MgCl2. Panormos Bay Au-Ag-Te mineralization, located 16 km away from the intrusive site, was deposited from cooler 200° to 300oC, and low to moderate saline (0.2 to 13.2 wt% NaCl eq.) mineralizing fluids. Au-Ag mineralization at Apigania Bay, which represents a late evolutionary phase, was deposited from even cooler (125o to 235oC) and dilute (0.2 to 6.8 wt % NaCl eq.) fluids. In all, the mineralization stage precipitation was controlled by two principal factors: the exsolution of gaseous phase and an increase in pH from 3.3 to 7.6
The costs, resource use, and cost-effectiveness of Clinical Nurse Specialist (CNSs) led interventions for patients with palliative care needs: a systematic review of international evidence
Background: Patients with palliative care (PC) needs do not access specialist palliative care services according to their necessities. Clinical Nurse Specialists (CNS) working across a variety of fields are playing an increasingly important role in the care of such patients, but there is limited knowledge of the extent to which their interventions are cost-effective.
Objectives: To present results from a systematic review of the international evidence on the costs, resource use and cost effectiveness of CNS led interventions for patients palliative care needs, defined as seriously ill patients and those with advanced disease or frailty who are unlikely to be cured, recover, or stabilize.
Design: Systematic review following PRISMA methodology.
Data sources: Medline, Embase, Cinahl and Cochrane library up to 2015. Studies focusing on the outcomes of CNS interventions for patients with PC needs, and including at least one economic outcome, were considered. The quality of studies was assessed using tools from the Joanna-Briggs-Institute.
Results: A total of 79 papers were included: 37 RCTs, 22 quasi-experimental studies, 7 service evaluations and other studies, and 13 economic analyses. The studies included a wide variety of interventions including clinical, support and education, as well as care coordination activities. The quality of the studies varied greatly.
Conclusions: CNSs interventions may be effective in reducing specific resource use such as hospitalizations /re-hospitalizations/admissions, length of stay, and health care costs. There is mixed evidence regarding their cost-effectiveness. Future studies should ensure that clinical nurse specialistsâ roles and activities are clearly described and evaluated
Measurement of the p\bar{p}\sqrt{s}$ = 1.8 TeV
We update the measurement of the top production cross section using the CDF
detector at the Fermilab Tevatron. This measurement uses decays to
the final states +jets and +jets. We search for quarks from
decays via secondary-vertex identification or the identification of
semileptonic decays of the and cascade quarks. The background to the
production is determined primarily through a Monte Carlo simulation.
However, we calibrate the simulation and evaluate its uncertainty using several
independent data samples. For a top mass of 175 , we measure
pb and pb using
the secondary vertex and the lepton tagging algorithms, respectively. Finally,
we combine these results with those from other decay channels and
obtain pb.Comment: The manuscript consists of 130 pages, 35 figures and 42 tables in
RevTex. The manuscript is submitted to Physical Review D. Fixed typo in
author lis
Dietary Modulation of Drosophila Sleep-Wake Behaviour
Background
A complex relationship exists between diet and sleep but despite its impact on human health, this relationship remains uncharacterized and poorly understood. Drosophila melanogaster is an important model for the study of metabolism and behaviour, however the effect of diet upon Drosophila sleep remains largely unaddressed.
Methodology/Principal Findings
Using automated behavioural monitoring, a capillary feeding assay and pharmacological treatments, we examined the effect of dietary yeast and sucrose upon Drosophila sleep-wake behaviour for three consecutive days. We found that dietary yeast deconsolidated the sleep-wake behaviour of flies by promoting arousal from sleep in males and shortening periods of locomotor activity in females. We also demonstrate that arousal from nocturnal sleep exhibits a significant ultradian rhythmicity with a periodicity of 85 minutes. Increasing the dietary sucrose concentration from 5% to 35% had no effect on total sucrose ingestion per day nor any affect on arousal, however it did lengthen the time that males and females remained active. Higher dietary sucrose led to reduced total sleep by male but not female flies. Locomotor activity was reduced by feeding flies Metformin, a drug that inhibits oxidative phosphorylation, however Metformin did not affect any aspects of sleep.
Conclusions
We conclude that arousal from sleep is under ultradian control and regulated in a sex-dependent manner by dietary yeast and that dietary sucrose regulates the length of time that flies sustain periods of wakefulness. These findings highlight Drosophila as an important model with which to understand how diet impacts upon sleep and wakefulness in mammals and humans
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