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  • 1
    Publication Date: 2019
    Description: 〈p〉Mitochondria and the endoplasmic reticulum (ER) have an intimate functional relationship due to tethering proteins that bring their membranes in close (~30 nm) apposition. One function of this interorganellar junction is to increase the efficiency of Ca〈sup〉2+〈/sup〉 transfer into mitochondria, thus stimulating mitochondrial respiration. Here, we showed that the ER cation-permeant channel polycystin 2 (PC2) functions to reduce mitochondria-ER contacts. In cell culture models, PC2 knockdown led to a 50% increase in mitofusin 2 (MFN2) expression, an outer mitochondrial membrane GTPase. Live-cell super-resolution and electron microscopy analyses revealed enhanced MFN2-dependent tethering between the ER and mitochondria in PC2 knockdown cells. PC2 knockdown also led to increased ER-mediated mitochondrial Ca〈sup〉2+〈/sup〉 signaling, bioenergetic activation, and mitochondrial density. Mutation or deletion of the gene encoding for PC2 results in autosomal dominant polycystic kidney disease (ADPKD), a condition characterized by numerous fluid-filled cysts. In cell culture models and mice with kidney-specific PC2 knockout, knockdown of MFN2 rescued defective mitochondrial Ca〈sup〉2+〈/sup〉 transfer and diminished cell proliferation in kidney cysts. Consistent with these results, cyst-lining epithelial cells from human ADPKD kidneys had a twofold increase in mitochondria and MFN2 expression. Our data suggest that PC2 normally serves to limit key mitochondrial proteins at the ER-mitochondrial interface and acts as a checkpoint for mitochondrial biogenesis and bioenergetics. Loss of this regulation may contribute to the increased oxidative metabolism and aberrant cell proliferation typical of kidney cysts in ADPKD.〈/p〉
    Print ISSN: 1945-0877
    Electronic ISSN: 1937-9145
    Topics: Biology , Medicine
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  • 2
    Publication Date: 2018-10-31
    Description: In order to ensure that the smart grid backbone communication network architecture model has a good universality, a two-layer QoS (Quality of Service) optimization modelling method of the backbone communication networks for power protection services is proposed. Firstly, taking the communication network capacity as a constraint, the minimum value of time-QoS of the system protection service is the optimization goal, and a two-layer capacity optimization model of service quality assurance is constructed. Secondly, the optimization model is simplified and a simulation experiment is designed. The validity of the proposed method is verified by numerical examples. The simulation results of the optical layer and the electrical layer satisfy the power system protection time delay specified in the power system protocol should meet the requirement of less than 50 ms.
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
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  • 3
    Publication Date: 2018-05-05
    Description: In view of the problem that the reheat steam temperature is lower than the design value in the operation of a 1000MW ultra-supercritical double reheat boiler in a power plant, this paper puts forward the method of flue gas recirculation (FGR) to improve it. Two schemes are put forward:the extraction of flue gas from the economizer or the draft fan to the bottom burner of the furnace. Indifferentload conditions,using the standard method of boiler thermodynamic calculation,the influence of different FGR schemes on boiler operation parameters is calculated. The results show that above FGR schemescan obviously improve thereheat steam temperature; with the increase of the amount of recirculating gas, the rise of the reheat steam temperature increases; with the decrease of the load, the influence of FGR on steam temperature increase; the scheme of extracting recirculating flue gas from the economizer outlet has little effect on the boiler efficiency, which is more suitable for the boi...
    Print ISSN: 1755-1307
    Electronic ISSN: 1755-1315
    Topics: Geography , Geosciences , Physics
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  • 4
    Publication Date: 2016-02-02
    Description: Author(s): M. N. Wilson, T. J. Williams, Y.-P. Cai, A. M. Hallas, T. Medina, T. J. Munsie, S. C. Cheung, B. A. Frandsen, L. Liu, Y. J. Uemura, and G. M. Luke We present muon spin rotation ( μ SR ) and susceptibility measurements on single crystals of isoelectronically doped URu 2 − x T x Si 2 (T = Fe, Os) for doping levels up to 50%. Zero field (ZF) μ SR measurements show long-lived oscillations demonstrating that an antiferromagnetic state exists down to low dopin… [Phys. Rev. B 93, 064402] Published Mon Feb 01, 2016
    Keywords: Magnetism
    Print ISSN: 1098-0121
    Electronic ISSN: 1095-3795
    Topics: Physics
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  • 5
    Publication Date: 2016-05-24
    Description: After decades of debate, a mostly satisfactory resolution of relationships among the 11 recognized holometabolan orders of insects has been reached based on nuclear genes, resolving one of the most substantial branches of the tree-of-life, but the relationships are still not well established with mitochondrial genome data. The main reasons have been the absence of sufficient data in several orders and lack of appropriate phylogenetic methods that avoid the systematic errors from compositional and mutational biases in insect mitochondrial genomes. In this study, we assembled the richest taxon sampling of Holometabola to date (199 species in 11 orders), and analyzed both nucleotide and amino acid data sets using several methods. We find the standard Bayesian inference and maximum-likelihood analyses were strongly affected by systematic biases, but the site-heterogeneous mixture model implemented in PhyloBayes avoided the false grouping of unrelated taxa exhibiting similar base composition and accelerated evolutionary rate. The inclusion of rRNA genes and removal of fast-evolving sites with the observed variability sorting method for identifying sites deviating from the mean rates improved the phylogenetic inferences under a site-heterogeneous model, correctly recovering most deep branches of the Holometabola phylogeny. We suggest that the use of mitochondrial genome data for resolving deep phylogenetic relationships requires an assessment of the potential impact of substitutional saturation and compositional biases through data deletion strategies and by using site-heterogeneous mixture models. Our study suggests a practical approach for how to use densely sampled mitochondrial genome data in phylogenetic analyses.
    Electronic ISSN: 1759-6653
    Topics: Biology
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  • 6
    Publication Date: 2012-07-10
    Description: Aims Nighttime sap flow of trees may indicate transpiration and/or recharge of stem water storage at night. This paper deals with the water use of Acacia mangium at night in the hilly lands of subtropical South China. Our primary goal was to reveal and understand the nature of nighttime sap flow and its functional significance. Methods Granier’s thermal dissipation method was used to determine the nighttime sap flux of A. mangium . Gas exchange system was used to estimate nighttime leaf transpiration and stomatal conductance of studied trees. Important Findings Nighttime sap flow was substantial and showed seasonal variation similar to the patterns of daytime sap flow in A. mangium . Mean nighttime sap flow was higher in the less precipitation year of 2004 (1122.4 mm) than in the more precipitation year of 2005 (1342.5 mm) since more daytime transpiration and low soil water availability in the relatively dry 2004 can be the cause of more nighttime sap flow. Although vapor pressure deficit and air temperature were significantly correlated with nighttime sap flow, they could only explain a small fraction of the variance in nighttime sap flow. The total accumulated water loss ( E L ) by transpiration of canopy leaves was only ~2.6–8.5% of the total nighttime sap flow ( E t ) during the nights of July 17–18 and 18–19, 2006. Therefore, it is likely that the nighttime sap flow was mainly used for refilling water in the trunk. The stem diameter at breast height, basal area and sapwood area explained much more variance of nighttime water recharge than environmental factors and other tree form features, such as tree height, stem length below the branch, and canopy size. The contribution of nighttime water recharge to the total transpiration ranged from 14.7 to 30.3% depending on different DBH class and was considerably higher in the dry season compared to the wet season.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
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  • 7
    Publication Date: 2012-03-16
    Description: The transpolar drift is strongly enriched in 228Ra accumulated on the wide Arctic shelves with subsequent rapid offshore transport. We present new data of Polarstern expeditions to the central Arctic and to the Kara and Laptev seas. Because 226Ra activities in Pacific waters are 30% higher than in Atlantic waters, we correct 226Ra for the Pacific admixture when normalizing 228Ra with 226Ra. The use of 228Ra decay as age marker critically depends on the constancy in space and time of the source activity, a condition that has not yet adequately been tested. While 228Ra decays during transit over the central basin, ingrowth of 228Th could provide an alternative age marker. The high 228Th/228Ra activity ratio (AR = 0.8–1.0) in the central basins is incompatible with a mixing model based on horizontal eddy diffusion. An advective model predicts that 228Th grows to an equilibrium AR, the value of which depends on the scavenging regime. The low AR over the Lomonosov Ridge (AR = 0.5) can be due to either rapid transport (minimum age without scavenging 1.1 year) or enhanced scavenging. Suspended particulate matter load (derived from beam transmission and particulate 234Th) and total 234Th depletion data show that scavenging, although extremely low in the central Arctic, is enhanced over the Lomonosov Ridge, making an age of 3 years more likely. The combined data of 228Ra decay and 228Th ingrowth confirm the existence of a recirculating gyre in the surface water of the eastern Eurasian Basin with a river water residence time of at least 3 years.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 8
    Publication Date: 2015-01-24
    Description: As the pupil size of ground-based telescopes increases, adaptive optics systems become more and more important for almost all astronomical observations. To test the performance of adaptive optics systems through simulation and with test bench experiments, we need to model the atmospheric turbulence with high fidelity. To fulfil this goal, a new method based on optimal sampling with a sparse spectrum model is discussed. This method can effectively simulate the atmospheric phase screen of any power spectrum with a controllable error budget.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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  • 9
    Publication Date: 2015-09-22
    Description: Analytical Chemistry DOI: 10.1021/acs.analchem.5b02247
    Print ISSN: 0003-2700
    Electronic ISSN: 1520-6882
    Topics: Chemistry and Pharmacology
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  • 10
    Publication Date: 2015-04-16
    Description: High-fidelity Monte Carlo simulation of atmospheric turbulence phase screens is important for performance testing of astronomical adaptive optics systems. With a sparse spectrum model and an optimal sampling method, it is possible to generate an atmospheric turbulence phase screen with high fidelity. However, the phase screen generation speed is limited by the algorithm structure of this technique. A non-uniform fast Fourier transform technique is proposed in this paper to accelerate phase screen generation speed. This method is able to generate huge atmospheric turbulence phase screens with high fidelity and an acceptable time-cost enabling practical adaptive optics simulations of forthcoming Extremely Large Telescopes.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
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