| 121. |
- Erlandson, R. E., et al.
(författare)
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Freja observations of electromagnetic ion cyclotron ELF waves and transverse oxygen ion acceleration on auroral field lines
- 1994
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Ingår i: Geophysical Research Letters. - 0094-8276. ; 21:17, s. 1855-1858
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Tidskriftsartikel (refereegranskat)abstract
- Extremely low-frequency (ELF) magnetic and electric field plasma wave emissions were recorded on 2 October 1993 on auroral field lines by the Magnetic Field Experiment during Freja orbit 4770. The ELF wave frequencies were below the local oxygen gyrofrequency (25 Hz) and between the helium and proton gyrofrequencies (100 to 400 Hz). The ELF waves, interpreted as electromagnetic ion cyclotron (EMIC) waves, were observed in a region of inverted-v-type electron precipitation. The EMIC waves were correlated over time with auroral and lower energy (≈ 100 eV) electrons, which are both possible sources of free energy, and also with transversely accelerated oxygen ions. The waves above the helium gyrofrequency were more closely correlated with the transverse oxygen ion acceleration than the waves below the oxygen gyrofrequency. These observations are consistent with a scenario in which electron beams generate EMIC waves, which then produce transverse oxygen ion acceleration through a gyroresonant interaction.
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| 122. |
- Gonzalez, Arantxa, et al.
(författare)
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Cardiac remodelling - Part 1: From cells and tissues to circulating biomarkers. A review from the Study Group on Biomarkers of the Heart Failure Association of the European Society of Cardiology
- 2022
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Ingår i: European Journal of Heart Failure. - : WILEY. - 1388-9842 .- 1879-0844. ; 24:6, s. 927-943
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Forskningsöversikt (refereegranskat)abstract
- Cardiac remodelling refers to changes in left ventricular structure and function over time, with a progressive deterioration that may lead to heart failure (HF) development (adverse remodelling) or vice versa a recovery (reverse remodelling) in response to HF treatment. Adverse remodelling predicts a worse outcome, whilst reverse remodelling predicts a better prognosis. The geometry, systolic and diastolic function and electric activity of the left ventricle are affected, as well as the left atrium and on the long term even right heart chambers. At a cellular and molecular level, remodelling involves all components of cardiac tissue: cardiomyocytes, fibroblasts, endothelial cells and leucocytes. The molecular, cellular and histological signatures of remodelling may differ according to the cause and severity of cardiac damage, and clearly to the global trend toward worsening or recovery. These processes cannot be routinely evaluated through endomyocardial biopsies, but may be reflected by circulating levels of several biomarkers. Different classes of biomarkers (e.g. proteins, non-coding RNAs, metabolites and/or epigenetic modifications) and several biomarkers of each class might inform on some aspects on HF development, progression and long-term outcomes, but most have failed to enter clinical practice. This may be due to the biological complexity of remodelling, so that no single biomarker could provide great insight on remodelling when assessed alone. Another possible reason is a still incomplete understanding of the role of biomarkers in the pathophysiology of cardiac remodelling. Such role will be investigated in the first part of this review paper on biomarkers of cardiac remodelling.
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| 123. |
- Heinkelmann, R., et al.
(författare)
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VLBI-derived troposphere parameters during CONT08
- 2011
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Ingår i: Journal of Geodesy. - : Springer Science and Business Media LLC. - 0949-7714 .- 1432-1394. ; 85:7, s. 377-393
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Tidskriftsartikel (refereegranskat)abstract
- Time-series of zenith wet and total troposphere delays as well as north and east gradients are compared, and zenith total delays (ZTD) are combined on the level of parameter estimates. Input data sets are provided by ten Analysis Centers (ACs) of the International VLBI Service for Geodesy and Astrometry (IVS) for the CONT08 campaign (12-26 August 2008). The inconsistent usage of meteorological data and models, such as mapping functions, causes systematics among the ACs, and differing parameterizations and constraints add noise to the troposphere parameter estimates. The empirical standard deviation of ZTD among the ACs with regard to an unweighted mean is 4.6 mm. The ratio of the analysis noise to the observation noise assessed by the operator/software impact (OSI) model is about 2.5. These and other effects have to be accounted for to improve the intra-technique combination of VLBI-derived troposphere parameters. While the largest systematics caused by inconsistent usage of meteorological data can be avoided and the application of different mapping functions can be considered by applying empirical corrections, the noise has to be modeled in the stochastic model of intra-technique combination. The application of different stochastic models shows no significant effects on the combined parameters but results in different mean formal errors: the mean formal errors of the combined ZTD are 2.3 mm (unweighted), 4.4 mm (diagonal), 8.6 mm [variance component (VC) estimation], and 8.6 mm (operator/software impact, OSI). On the one hand, the OSI model, i.e. the inclusion of off-diagonal elements in the cofactor-matrix, considers the reapplication of observations yielding a factor of about two for mean formal errors as compared to the diagonal approach. On the other hand, the combination based on VC estimation shows large differences among the VCs and exhibits a comparable scaling of formal errors. Thus, for the combination of troposphere parameters a combination of the two extensions of the stochastic model is recommended.
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| 124. |
- Jiang, Xuehe, et al.
(författare)
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Multifunctional Cellulose Nanofibrils-GdF3 Nanoparticles Hybrid Gel and Its Potential Uses for Drug Delivery and Magnetic Resonance Imaging
- 2023
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Ingår i: ACS Applied Nano Materials. - : American Chemical Society (ACS). - 2574-0970. ; 6:22, s. 21182-21193
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Tidskriftsartikel (refereegranskat)abstract
- A multifunctional hybrid gel based on cellulose nanofibrils (CNFs) was developed by grafting on its surface stearyl acrylate (PSA) and gadolinium(III) fluoride nanoparticles (GdF3 NPs) via Cu0-mediated surface-initiated radical polymerization (SET-LRP) while encapsulating antimicrobial peptides in it. GdF3 NPs were first surface-modified with 11-phosphonoundecyl acrylate (PDA) to participate in the SET-LRP and cross-linked the grafted polymer-modified CNF. Several characterizations of the hybrid material (GdF3-PSA-CNF) were carried out, such as Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, and microscopic analyses. The grafted PSA and cross-linked GdF3 NPs created sophisticated networks in the CNF-based gel, presenting outstanding rheological properties and promising three-dimensional (3D) printability of this hybrid material (GdF3-PSA-CNF). The nanostructures of GdF3 NPs and their incorporated CNF species were characterized via small-angle X-ray scattering (SAXS). In addition, due to the unique intrinsic property of the GdF3 nanoparticles, properties for magnetic resonance imaging (MRI) of GdF3-PSA-CNF were investigated, showing the potential application as a contrast agent. Finally, the encapsulation of the antimicrobial peptides added another function to the hybrid material, evaluated by an antimicrobial test against methicillin-resistant Staphylococcus aureus (MRSA) in vitro.
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| 125. |
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| 126. |
- Leng, Melanie J., et al.
(författare)
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Understanding past climatic and hydrological variability in the Mediterranean from Lake Prespa sediment isotope and geochemical record over the last glacial cycle
- 2013
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 66, s. 123-136
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Tidskriftsartikel (refereegranskat)abstract
- Here we present stable isotope and geochemical data from Lake Prespa (Macedonia/Albania border) over the Last Glacial cycle (Marine Isotope Stages 5-1) and discuss past lake hydrology and climate (TIC, oxygen and carbon isotopes), as well as responses to climate of terrestrial and aquatic vegetation (TOC, Rock Eval pyrolysis, carbon isotopes, pollen). The Lake Prespa sediments broadly fall into 5 zones based on their sedimentology, geochemistry, palynology and the existing chronology. The Glacial sediments suggest low supply of carbon to the lake, but high summer productivity; intermittent siderite layers suggest that although the lake was likely to have mixed regularly leading to enhanced oxidation of organic matter, there must have been within sediment reducing conditions and methanogenesis. MIS 5 and 1 sediments suggest much more productivity, higher rates of organic material preservation possibly due to more limited mixing with longer periods of oxygen-depleted bottom waters. We also calculated lakewater delta O-18 from siderite (authigenic/Glacial) and calcite (endogenic/Holocene) and show much lower lakewater delta O-18 values in the Glacial when compared to the Holocene, suggesting the lake was less evaporative in the Glacial, probably as a consequence of cooler summers and longer winter ice cover. In the Holocene the oxygen isotope data suggests general humidity, with just 2 marked arid phases, features observed in other Eastern and Central Mediterranean lakes. (C) 2012 Elsevier Ltd. All rights reserved.
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| 127. |
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| 128. |
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| 129. |
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| 130. |
- McLane, L. T., et al.
(författare)
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Spatial Organization and Mechanical Properties of the Pericellular Matrix on Chondrocytes
- 2013
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495. ; 104:5, s. 986-996
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Tidskriftsartikel (refereegranskat)abstract
- A voluminous polymer coat adorns the surface of many eukaryotic cells. Although the pericellular matrix (PCM) often extends several microns from the cell surface, its macromolecular structure remains elusive. This massive cellular organelle negotiates the cell’s interaction with surrounding tissue, influencing important processes such as cell adhesion, mitosis, locomotion, molecular sequestration, and mechanotransduction. Investigations of the PCM’s architecture and function have been hampered by the difficulty of visualizing this invisible hydrated structure without disrupting its integrity. In this work, we establish several assays to noninvasively measure the ultrastructure of the PCM. Optical force probe assays show that the PCM of rat chondrocyte joint (RCJ-P) cells easily reconfigures around optically manipulated microparticles, allowing the probes to penetrate into rather than compress the matrix. We report distinct changes in forces measured from PCMs treated with exogenous aggrecan, illustrating the assay’s potential to probe proteoglycan distribution. Measurements reveal an exponentially increasing osmotic force in the PCM arising from an inherent concentration gradient. With this result, we estimate the variation of the PCM’s mesh size (correlation length) to range from ∼100 nm at the surface to 500 nm at its periphery. Quantitative particle exclusion assays confirm this prediction and show that the PCM acts like a sieve. These assays provide a much-needed tool to study PCM ultrastructure and its poorly defined but important role in fundamental cellular processes.
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