183 research outputs found

    Vertical hydraulic conductivity of a clayey-silt aquitard: accelerated fluid flow in a centrifuge permeameter compared with in situ conditions

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    This discussion paper is a preprint. It has been under review for the journal Hydrology and Earth System Sciences (HESS). The revised manuscript was not accepted.Evaluating the possibility of leakage through low permeability geological strata is critically important for sustainable water supplies, extraction of fuels from strata such as coal beds, and confinement of waste within the earth. Characterizing low or negligible flow rates and transport of solutes can require impractically long periods of field or laboratory testing, but is necessary for evaluations over regional areas and over multi-decadal timescales. The current work reports a custom designed centrifuge permeameter (CP) system, which can provide relatively rapid and reliable hydraulic conductivity (K) measurement compared to column permeameter tests at standard gravity (1g). Linear fluid velocity through a low K porous sample is linearly related to g-level during a CP flight unless consolidation or geochemical reactions occur. The CP module is designed to fit within a standard 2 m diameter, geotechnical centrifuge with a capacity for sample dimensions of 30 to 100 mm diameter and 30 to 200 mm in length. At maximum RPM the resultant centrifugal force is equivalent to 550g at base of sample or a total stress of ~2 MPa. K is calculated by measuring influent and effluent volumes. A custom designed mounting system allows minimal disturbance of drill core samples and a centrifugal force that represents realistic in situ stress conditions is applied. Formation fluids were used as influent to limit any shrink-swell phenomena which may alter the resultant K value. Vertical hydraulic conductivity (Kv) results from CP testing of core from the sites in the same clayey silt formation varied (10−7 to 10−9 m s−1, n = 14) but higher than 1g column permeameter tests of adjacent core using deionized water (10−9 to 10−11 m s−1, n = 7). Results at one site were similar to in situ Kv values (3 × 10−9 m s−1) from pore pressure responses within a 30 m clayey sequence in a homogenous area of the formation. Kv sensitivity to sample heterogeneity was observed, and anomalous flow via preferential pathways could be readily identified. Results demonstrate the utility of centrifuge testing for measuring minimum K values that can contribute to assessments of geological formations at large scale. The importance of using realistic stress conditions and influent geochemistry during hydraulic testing is also demonstrated.Australian Research CouncilNational Water Commissio

    Accelerated gravity testing of aquitard core permeability and implications at formation and regional scale

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    Evaluating the possibility of leakage through low-permeability geological strata is critically important for sustainable water supplies, the extraction of fuels from coal and other strata, and the confinement of waste within the earth. The current work demonstrates that relatively rapid and realistic vertical hydraulic conductivity (Kv) measurements of aquitard cores using accelerated gravity can constrain and compliment larger-scale assessments of hydraulic connectivity. Steady-state fluid velocity through a low-K porous sample is linearly related to accelerated gravity (g level) in a centrifuge permeameter (CP) unless consolidation or geochemical reactions occur. A CP module was custom designed to fit a standard 2 m diameter geotechnical centrifuge (550 g maximum) with a capacity for sample dimensions up to 100 mm diameter and 200 mm length, and a total stress of  ∼  2 MPa at the base of the core. Formation fluids were used as influent to limit any shrink–swell phenomena, which may alter the permeability. Kv results from CP testing of minimally disturbed cores from three sites within a clayey-silt formation varied from 10−10 to 10−7  m s−1 (number of samples, n = 18). Additional tests were focussed on the Cattle Lane (CL) site, where Kv within the 99 % confidence interval (n = 9) was 1.1 × 10−9 to 2.0 × 10−9 m s−1. These Kv results were very similar to an independent in situ Kv method based on pore pressure propagation though the sequence. However, there was less certainty at two other core sites due to limited and variable Kv data. Blind standard 1 g column tests underestimated Kv compared to CP and in situ Kv data, possibly due to deionised water interactions with clay, and were more time-consuming than CP tests. Our Kv results were compared with the set-up of a flow model for the region, and considered in the context of heterogeneity and preferential flow paths at site and formation scale. Reasonable assessments of leakage and solute transport through aquitards over multi-decadal timescales can be achieved by accelerated core testing together with complimentary hydrogeological monitoring, analysis, and modelling

    Disulfide-activated protein kinase G Iα regulates cardiac diastolic relaxation and fine-tunes the Frank-Starling response.

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    The Frank-Starling mechanism allows the amount of blood entering the heart from the veins to be precisely matched with the amount pumped out to the arterial circulation. As the heart fills with blood during diastole, the myocardium is stretched and oxidants are produced. Here we show that protein kinase G Iα (PKGIα) is oxidant-activated during stretch and this form of the kinase selectively phosphorylates cardiac phospholamban Ser16-a site important for diastolic relaxation. We find that hearts of Cys42Ser PKGIα knock-in (KI) mice, which are resistant to PKGIα oxidation, have diastolic dysfunction and a diminished ability to couple ventricular filling with cardiac output on a beat-to-beat basis. Intracellular calcium dynamics of ventricular myocytes isolated from KI hearts are altered in a manner consistent with impaired relaxation and contractile function. We conclude that oxidation of PKGIα during myocardial stretch is crucial for diastolic relaxation and fine-tunes the Frank-Starling response

    Zircon ages in granulite facies rocks: decoupling from geochemistry above 850 °C?

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    Granulite facies rocks frequently show a large spread in their zircon ages, the interpretation of which raises questions: Has the isotopic system been disturbed? By what process(es) and conditions did the alteration occur? Can the dates be regarded as real ages, reflecting several growth episodes? Furthermore, under some circumstances of (ultra-)high-temperature metamorphism, decoupling of zircon U–Pb dates from their trace element geochemistry has been reported. Understanding these processes is crucial to help interpret such dates in the context of the P–T history. Our study presents evidence for decoupling in zircon from the highest grade metapelites (> 850 °C) taken along a continuous high-temperature metamorphic field gradient in the Ivrea Zone (NW Italy). These rocks represent a well-characterised segment of Permian lower continental crust with a protracted high-temperature history. Cathodoluminescence images reveal that zircons in the mid-amphibolite facies preserve mainly detrital cores with narrow overgrowths. In the upper amphibolite and granulite facies, preserved detrital cores decrease and metamorphic zircon increases in quantity. Across all samples we document a sequence of four rim generations based on textures. U–Pb dates, Th/U ratios and Ti-in-zircon concentrations show an essentially continuous evolution with increasing metamorphic grade, except in the samples from the granulite facies, which display significant scatter in age and chemistry. We associate the observed decoupling of zircon systematics in high-grade non-metamict zircon with disturbance processes related to differences in behaviour of non-formula elements (i.e. Pb, Th, U, Ti) at high-temperature conditions, notably differences in compatibility within the crystal structure

    Serotonin regulates prostate growth through androgen receptor modulation

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    Serotonin regulates prostate growth through androgen receptor modulationAging and testosterone almost inexorably cause benign prostatic hyperplasia (BPH) in Human males. However, etiology of BPH is largely unknown. Serotonin (5-HT) is produced by neuroendocrine prostatic cells and presents in high concentration in normal prostatic transition zone, but its function in prostate physiology is unknown. Previous evidence demonstrated that neuroendocrine cells and 5-HT are decreased in BPH compared to normal prostate. Here, we show that 5-HT is a strong negative regulator of prostate growth. In vitro, 5-HT inhibits rat prostate branching through down-regulation of androgen receptor (AR). This 5-HT's inhibitory mechanism is also present in human cells of normal prostate and BPH, namely in cell lines expressing AR when treated with testosterone. In both models, 5-HT's inhibitory mechanism was replicated by specific agonists of 5-Htr1a and 5-Htr1b. Since peripheral 5-HT production is specifically regulated by tryptophan hydroxylase 1(Tph1), we showed that Tph1 knockout mice present higher prostate mass and up-regulation of AR when compared to wild-type, whereas 5-HT treatment restored the prostate weight and AR levels. As 5-HT is decreased in BPH, we present here evidence that links 5-HT depletion to BPH etiology through modulation of AR. Serotoninergic prostate pathway should be explored as a new therapeutic target for BPH.Projects NORTE-01-0246-FEDER-000012, NORTE-01-0145-FEDER-000013 and NORTE-01-0145-FEDER-000023, supported by the Northern Portugal Regional Operational Program (NORTE 2020), under the Portugal 2020 Partnership Agreement, through the European Regional Development Fund (FEDER) and Bolsa de Investigação GSK Inovação em Urologia 2012info:eu-repo/semantics/publishedVersio

    Challenging the heterogeneity of disease presentation in malignant melanoma-impact on patient treatment

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    There is an increasing global interest to support research areas that can assist in understanding disease and improving patient care. The National Cancer Institute (NIH) has identified precision medicine-based approaches as key research strategies to expedite advances in cancer research. The Cancer Moonshot program ( https://www.cancer.gov/research/key-initiatives/moonshot-cancer-initiative ) is the largest cancer program of all time, and has been launched to accelerate cancer research that aims to increase the availability of therapies to more patients and, ultimately, to eradicate cancer. Mass spectrometry-based proteomics has been extensively used to study the molecular mechanisms of cancer, to define molecular subtypes of tumors, to map cancer-associated protein interaction networks and post-translational modifications, and to aid in the development of new therapeutics and new diagnostic and prognostic tests. To establish the basis for our melanoma studies, we have established the Southern Sweden Malignant Melanoma Biobank. Tissues collected over many years have been accurately characterized with respect to the tumor and patient information. The extreme variability displayed in the protein profiles and the detection of missense mutations has confirmed the complexity and heterogeneity of the disease. It is envisaged that the combined analysis of clinical, histological, and proteomic data will provide patients with a more personalized medical treatment. With respect to disease presentation, targeted treatment and medical mass spectrometry analysis and imaging, this overview report will outline and summarize the current achievements and status within malignant melanoma. We present data generated by our cancer research center in Lund, Sweden, where we have built extensive capabilities in biobanking, proteogenomics, and patient treatments over an extensive time period
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