| 1191. |
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| 1192. |
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| 1193. |
- Gusmeroli, Alessio, et al.
(författare)
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Vertical seismic profiling of glaciers : appraising multi-phase mixing models
- 2013
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Ingår i: Annals of Glaciology. - 0260-3055 .- 1727-5644. ; 54:64, s. 115-123
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the speed of compressional waves in a polythermal glacier by, first, predicting them from a simple three-phase (ice, air, water) model derived from a published ground-penetrating radar study, and then comparing them with field data from four orthogonally orientated walkaway vertical seismic profiles (VSPs) acquired in an 80 m deep borehole drilled in the ablation area of Storglaciaren, northern Sweden. The model predicts that the P-wave speed increases gradually with depth from 3700 m s(-1) at the surface to 3760 m s(-1) at 80 m depth, and this change is almost wholly caused by a reduction in air content from 3% at the surface to <0.5% at depth. Changes in P-wave speed due to water content variations are small (<10 m s(-1)); the model's seismic cold-temperate transition surface (CTS) is characterized by a 0.3% decrease downwards in P-wave speed (about ten times smaller than the radar CTS). This lack of sensitivity, and the small contrast at the CTS, makes seismically derived water content estimation very challenging. Nevertheless, for down-going direct-wave first arrivals for zero- and near-offset VSP shots, we find that the model-predicted travel times and field observations agree to within 0.2 ms, i.e. less than the observational uncertainties.
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| 1194. |
- Hacar, A., et al.
(författare)
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Initial Conditions for Star Formation: a Physical Description of the Filamentary ISM
- 2023
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Ingår i: ASP Conference Series. ; 534, s. 153-
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Konferensbidrag (refereegranskat)abstract
- The interstellar medium (ISM) contains filamentary structure over a wide range of scales. Understanding the role of this structure, both as a conduit of gas across the scales and a diagnostic tool of local physics, is a major focus of star formation studies. We review recent progress in studying filamentary structure in the ISM, interpreting its properties in terms of physical processes, and exploring formation and evolution scenarios. We include structures from galactic-scale filaments to tenth-of-a-parsec scale filaments, comprising both molecular and atomic structures, from both observational and theoretical perspectives. In addition to the literature overview, we assemble a large amount of catalog data from different surveys and provide the most comprehensive census of filamentary structures to date. Our census consists of 22 803 filamentary structures, facilitating a holistic perspective and new insights. We use our census to conduct a meta-analysis, leading to a description of filament properties over four orders of magnitudes in length and eight in mass. Our analysis emphasize the hierarchical and dynamical nature of filamentary structures. Filaments do not live in isolation, nor they generally resemble static structures close to equilibrium. We propose that accretion during filament formation and evolution sets some of the key scaling properties of filaments. This highlights the role of accretion during filament formation and evolution and also in setting the initial conditions for star formation. Overall, the study of filamentary structures during the past decade has been observationally driven. While great progress has been made on measuring the basic properties of filaments, our understanding of their formation and evolution is clearly lacking. In this context, we identify a number of directions and questions we consider most pressing for the field.
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| 1195. |
- Hadjigeorgiou, E., et al.
(författare)
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A systematic review into expert knowledge elicitation methods for emerging food and feed risk identification
- 2022
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Ingår i: Food Control. - : Elsevier BV. - 0956-7135 .- 1873-7129. ; 136, s. 108848-
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Forskningsöversikt (refereegranskat)abstract
- An emerging risk results "... from a newly identified hazard to which a significant exposure may occur, or from an unexpected new or increased significant exposure and/or susceptibility to a known hazard". In the field of emerging food and feed risks, expert knowledge elicitation methodologies represent important tools for identifying and addressing data gaps associated with emerging risk identification, particularly under conditions of risk uncertainty and/or ambiguity. A systematic review was conducted to identify expert knowledge elicitation methods which have been used in the context of emerging food and feed risks. The primary research questions were which existing expert knowledge elicitation methodologies have been used to study emerging food and feed risks? and what contexts or situations have been studied using expert knowledge elicitation methodologies in relation to emerging food and feed-related risks? Three databases were searched: Web of Science Core Collection, Scopus, and Google Scholar. Searches covered all studies published from 1998 onwards. A total of 59 studies were included in the review following the application of the inclusion and exclusion criteria. Given the heterogeneity of the included studies, a thematic analysis was applied to assess these papers in relation to the research questions. There was no one expert knowledge elicitation method consistently adopted for the identification of a specific type of emerging food and feed risk. Method triangulation was observed in 23 studies and was reported to improve the validity of results in 15 of these. Most published research considered emerging risks associated with societal controversy ("ambiguous risks"). Although the use of methodological triangulation appears to be helpful in relation to understanding emerging food and feed risks, future research into the development of a harmonised framework will enable the identification, processing, and evaluation of emerging food risks in a systemic way which can facilitate comparative analysis and harmonise mitigation strategies to address emerging risks and their drivers.
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| 1196. |
- Hamlett, Eric D., et al.
(författare)
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Neuronal exosomes reveal Alzheimer's disease biomarkers in Down syndrome
- 2017
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Ingår i: Alzheimer's & Dementia. - : Elsevier. - 1552-5260 .- 1552-5279. ; 13:5, s. 541-549
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Individuals with Down syndrome (DS) exhibit Alzheimer's disease (AD) neuropathology and dementia early in life. Blood biomarkers of AD neuropathology would be valuable, as non-AD intellectual disabilities of DS and AD dementia overlap clinically. We hypothesized that elevations of amyloid-β (Aβ) peptides and phosphorylated-tau in neuronal exosomes may document preclinical AD.METHODS: AD neuropathogenic proteins Aβ1-42, P-T181-tau, and P-S396-tau were quantified by enzyme-linked immunosorbent assays in extracts of neuronal exosomes purified from blood of individuals with DS and age-matched controls.RESULTS: Neuronal exosome levels of Aβ1-42, P-T181-tau, and P-S396-tau were significantly elevated in individuals with DS compared with age-matched controls at all ages beginning in childhood. No significant gender differences were observed.DISCUSSION: These early increases in Aβ1-42, P-T181-tau, and P-S396-tau in individuals with DS may provide a basis for early intervention as targeted treatments become available.
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| 1197. |
- Hammarquist, Anders, 1974, et al.
(författare)
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V-shaped switching ferroelectric liquid crystal structure stabilized by dielectric surface layers
- 2008
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Ingår i: Physical Review E. - 2470-0045 .- 2470-0053. ; 77:3
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Tidskriftsartikel (refereegranskat)abstract
- The "V-shaped switching" mode in high polarization ferroelectric liquid crystals was studied with the aim of stabilizing the monostable bookshelf structure with the spontaneous polarization parallel to the glass plates. The director field in such cells was confirmed to be sensitive to both the liquid crystal properties and the cell parameters. In cells with only polyimide alignment layers, hysteresis free switching was never obtained, with bistable and asymmetric monostable structures compromising the zero-field dark state and preventing an ideal, hysteresis-free analog response. By incorporating a SiO(2) layer between the ITO electrode and the polyimide, the undesired states were suppressed and essentially hysteresis-free switching was obtained for driving frequencies in the range 0.2-200 Hz. Cells rubbed only on one side give more uniform alignment than cells rubbed on both sides but their inherent asymmetry shifts the long-term dark state away from 0 V and causes the response to gray level voltage modulation to be slightly asymmetric. The formation of different types of states as a function of the values of the surface parameters, and the observed stabilization of the V-shaped switching structure by the dielectric surface layers, are in good agreement with an earlier analysis by Copic et al.
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| 1198. |
- Hastoy, B., et al.
(författare)
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Fusion pore in exocytosis: More than an exit gate? A beta-cell perspective
- 2017
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Ingår i: Cell Calcium. - : Elsevier BV. - 0143-4160. ; 68, s. 45-61
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Forskningsöversikt (refereegranskat)abstract
- Secretory vesicle exocytosis is a fundamental biological event and the process by which hormones (like insulin) are released into the blood. Considerable progress has been made in understanding this precisely orchestrated sequence of events from secretory vesicle docked at the cell membrane, hemifusion, to the opening of a membrane fusion pore. The exact biophysical and physiological regulation of these events implies a close interaction between membrane proteins and lipids in a confined space and constrained geometry to ensure appropriate delivery of cargo. We consider some of the still open questions such as the nature of the initiation of the fusion pore, the structure and the role of the Soluble N-ethylmaleimide-sensitive-factor Attachment protein REceptor (SNARE) transmembrane domains and their influence on the dynamics and regulation of exocytosis. We discuss how the membrane composition and protein-lipid interactions influence the likelihood of the nascent fusion pore forming. We relate these factors to the hypothesis that fusion pore expansion could be affected in type-2 diabetes via changes in disease-related gene transcription and alterations in the circulating lipid profile. Detailed characterisation of the dynamics of the fusion pore in vitro will contribute to understanding the larger issue of insulin secretory defects in diabetes.
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| 1199. |
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| 1200. |
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