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  • 1
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    Online Resource
    Intrinsic functional connectivity, CSF biomarker profiles and their relation to cognitive function in mild cognitive impairment
    Cambridge University Press (CUP) ; 2020
    In:  Acta Neuropsychiatrica Vol. 32, No. 4 ( 2020-08), p. 206-213
    Details
    In: Acta Neuropsychiatrica, Cambridge University Press (CUP), Vol. 32, No. 4 ( 2020-08), p. 206-213
    Abstract: Mild cognitive impairment (MCI) often precedes Alzheimer’s Dementia (AD), and in a high proportion of individuals affected by MCI, there are already neuropathological processes ongoing that become more evident when patients progress to AD. Accordingly, there is a need for reliable biomarkers to distinguish between normal aging and incipient AD. Recent research suggests that, in addition to established biomarkers such as CSF Aß42, total tau and hyperphosphorylated tau, resting state connectivity established by functional magnetic resonance imaging might also be a feasible biomarker for prodromal stages of AD. In order to explore this possibility, we investigated resting state functional connectivity as well as cerebrospinal fluid (CSF) biomarker profiles in patients with MCI ( n = 30; age 66.43 ± 7.06 years) and cognitively healthy controls ( n = 38; age 66.89 ± 7.12 years). CSF Aß42, total tau and hyperphosphorylated tau concentrations were correlated with measures of cognitive performance (immediate and delayed recall, global cognition, processing speed). Moreover, MCI-related alterations in intrinsic functional connectivity within the default mode network were investigated using functional resting state MRI. As expected, MCI patients showed decreased CSF Aß42 and increased total tau concentrations. These alterations were associated with cognitive performance. However, there were no differences between MCI patients and cognitively healthy controls regarding intrinsic functional connectivity. In conclusion, our results indicate that CSF protein profiles seem to be more closely related to cognitive decline than alterations in resting state activity. Thus, resting state connectivity might not be a reliable biomarker for early stages of AD.
    Type of Medium: Online Resource
    ISSN: 0924-2708 , 1601-5215
    URL: Article
    DOI: 10.1017/neu.2019.49
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2020
    detail.hit.zdb_id: 2077830-2
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  • 2
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    High-fidelity Human Patient Simulators Compared with Human Actors in an Unannounced Mass-Casualty Exercise
    Cambridge University Press (CUP) ; 2014
    In:  Prehospital and Disaster Medicine Vol. 29, No. 2 ( 2014-04), p. 176-182
    Details
    In: Prehospital and Disaster Medicine, Cambridge University Press (CUP), Vol. 29, No. 2 ( 2014-04), p. 176-182
    Abstract: High-fidelity simulators (HFSs) have been shown to prompt critical actions at a level equal to that of trained human actors (HAs) and increase perceived realism in intrahospital mass-casualty incident (MCI) exercises. For unannounced prehospital MCI exercises, however, no data are available about the feasibility of incorporating HFSs. This case report describes the integration of HFSs in such an unannounced prehospital MCI drill with HAs and provides data about the differences concerning triage, treatment, and transport of HFSs and HAs with identical injury patterns. For this purpose, 75 actors and four high-fidelity simulators were subdivided into nine groups defined by a specific injury pattern. Four HFSs and six HAs comprised a group suffering from traumatic brain injury and blunt abdominal trauma. Triage results, times for transport, and number of diagnostic and therapeutic tasks were recorded. Means were compared by t test or one-way ANOVA. Triage times and results did not differ between actors and simulators. The number of diagnostic (1.25, SD = 0.5 in simulators vs 3.5, SD = 1.05 in HAs; P = .010) and therapeutic tasks (2.0, SD = 1.6 in simulators vs 4.8, SD = 0.4 in HAs; P = .019) were significantly lower in simulators. Due to difficulties in treating and evacuating the casualties from the site of the accident in a timely manner, all simulators died. Possible causal factors and strategies are discussed, with the aim of increasing the utility of simulators in emergency medicine training. Schulz CM , Skrzypczak M , Raith S , Hinzmann D , Krautheim V , Heuser F , Mayer V , Kreuzer C , Himsl M , Holl M , Lipp C , Kochs EF , Wagner KJ . High-fidelity human patient simulators compared with human actors in an unannounced mass-casualty exercise . Prehosp Disaster Med . 2014 ; 29 ( 2 ): 1 - 7 .
    Type of Medium: Online Resource
    ISSN: 1049-023X , 1945-1938
    URL: Article
    DOI: 10.1017/S1049023X14000223
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2014
    detail.hit.zdb_id: 2162069-6
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  • 3
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    Estimating local surface glacier mass balance from migration of the 1918 Katla eruption tephra layer on Sléttjökull, southern Iceland
    Cambridge University Press (CUP) ; 2023
    In:  Annals of Glaciology
    Details
    In: Annals of Glaciology, Cambridge University Press (CUP)
    Abstract: We use the apparent horizontal shift of an englacial tephra layer outcrop to calculate local glacier mass balance on Sléttjökull, a lobe of Mýrdalsjökull in Southern Iceland. For this approach, the dipping angle of the englacial tephra layer in the glacier upstream of the outcrop and the flow velocity of the ice need to be known. An earlier investigation was expanded by the application of ground-penetrating radar, detecting the depth of the tephra along tracks with a total length of 10 km. Interpolation between the tracks enables us to derive the dipping angle of the layer along several flow lines. Together with glacier surface velocities, determined from feature tracking, we are able to estimate the local surface mass balance from the horizontal displacement of the tephra outcrop using freely available satellite imagery without additional fieldwork. The earlier local balance series was extended to the period 2014/15 to 2019/20. Although the results for the individual profiles differ slightly from each other, they show the same temporal pattern and clear variations from year to year. The results are compared to traditional mass-balance data from Hofsjökull. The two series show a good agreement in their interannual variability.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.1017/aog.2022.1
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2122400-6
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  • 4
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    Bacterial diversity in snow from mid-latitude mountain areas: Alps, Eastern Anatolia, Karakoram and Himalaya
    Cambridge University Press (CUP) ; 2018
    In:  Annals of Glaciology Vol. 59, No. 77 ( 2018-12), p. 10-20
    Details
    In: Annals of Glaciology, Cambridge University Press (CUP), Vol. 59, No. 77 ( 2018-12), p. 10-20
    Abstract: Snow can be considered an independent ecosystem that hosts active microbial communities. Snow microbial communities have been extensively investigated in the Arctic and in the Antarctica, but rarely in mid-latitude mountain areas. In this study, we investigated the bacterial communities of snow collected in four glacierized areas (Alps, Eastern Anatolia, Karakoram and Himalaya) by high-throughput DNA sequencing. We also investigated the origin of the air masses that produced the sampled snowfalls by reconstructing back-trajectories. A standardized approach was applied to all the analyses in order to ease comparison among different communities and geographical areas. The bacterial communities hosted from 25 to 211 Operational Taxonomic Units (OTUs), and their structure differed significantly between geographical areas. This suggests that snow bacterial communities may largely derive from ‘local’ air bacteria, maybe by deposition of airborne particulate of local origin that occurs during snowfall. However, some evidences suggest that a contribution of bacteria collected during air mass uplift to snow communities cannot be excluded, particularly when the air mass that originated the snow event is particularly rich in dust.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.1017/aog.2018.18
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2018
    detail.hit.zdb_id: 2122400-6
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  • 5
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    Comparison of elastic moduli from seismic diving-wave and ice-core microstructure analysis in Antarctic polar firn
    Cambridge University Press (CUP) ; 2019
    In:  Annals of Glaciology Vol. 60, No. 79 ( 2019-09), p. 220-230
    Details
    In: Annals of Glaciology, Cambridge University Press (CUP), Vol. 60, No. 79 ( 2019-09), p. 220-230
    Abstract: We compared elastic moduli in polar firn derived from diving wave refraction seismic velocity analysis, firn-core density measurements and microstructure modelling based on firn-core data. The seismic data were obtained with a small electrodynamic vibrator source near Kohnen Station, East Antarctica. The analysis of diving waves resulted in velocity–depth profiles for different wave types (P-, SH- and SV-waves). Dynamic elastic moduli of firn were derived by combining P- and S-wave velocities and densities obtained from firn-core measurements. The structural finite-element method (FEM) was used to calculate the components of the elastic tensor from firn microstructure derived from X-ray tomography of firn-core samples at depths of 10, 42, 71 and 99 m, providing static elastic moduli. Shear and bulk moduli range from 0.39 to 2.42 GPa and 0.68 to 2.42 GPa, respectively. The elastic moduli from seismic observations and the structural FEM agree within 8.5% for the deepest achieved values at a depth of 71 m, and are within the uncertainty range. Our observations demonstrate that the elastic moduli of the firn can be consistently obtained from two independent methods which are based on dynamic (seismic) and static (tomography and FEM) observations, respectively, for deeper layers in the firn below ~10 m depth.
    Type of Medium: Online Resource
    ISSN: 0260-3055 , 1727-5644
    URL: Article
    DOI: 10.1017/aog.2019.10
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2019
    detail.hit.zdb_id: 2122400-6
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  • 6
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    Detection of crevassed areas with minimum geometric information: Vernagtferner case study
    Cambridge University Press (CUP) ; 2023
    In:  Journal of Glaciology
    Details
    In: Journal of Glaciology, Cambridge University Press (CUP)
    Abstract: Crevasses pose severe risks for mountaineers and field glaciologists. Smaller cracks between 0.5 and 2 m are still dangerous, but often not visible in medium resolution satellite imagery. If they are snow covered, they are completely undetectable by optical sensors. We set out to develop an approach to detect potentially crevassed areas by a minimum of geometric data, and to make the method generally applicable to glacier regions. On Vernagtferner, we compared a reference dataset of crevasses observed in high-resolution optical imagery with the curvature of the ice surface and the spatial gradients in driving stress. Both parameters can be derived from a digital surface model and a bedrock model, derived from ice thickness measurements. The correlation patterns show that crevasses preferably form in convex areas and in areas where the driving stress rapidly increases. This corresponds with the theory of crevasse formation. Although the method still misclassifies larger parts, the approach has the potential to define probable non-crevassed areas as well as to aid the planning of safe routes.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.1017/jog.2023.12
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2023
    detail.hit.zdb_id: 2140541-4
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  • 7
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    High altitude accumulation and preserved climate information in the western Pamir, observations from the Fedchenko Glacier accumulation basin
    Cambridge University Press (CUP) ; 2020
    In:  Journal of Glaciology Vol. 66, No. 256 ( 2020-04), p. 219-230
    Details
    In: Journal of Glaciology, Cambridge University Press (CUP), Vol. 66, No. 256 ( 2020-04), p. 219-230
    Abstract: The accumulation region of Fedchenko Glacier represents an extensive snow reservoir in the Pamir Mountains feeding the longest glacier in Central Asia. Observed elevation changes indicate a continuous ice loss in the ablation region of Fedchenko Glacier since 1928, while the mass balance of the accumulation region is largely unknown. In this study, we show that accumulation varies considerably in the main accumulation basin, with accumulation rates up to 2400 mm w.e. a −1 in the West, decreasing to 〈 1000 mm w.e. a −1 in the center, although the elevation difference is 〈 200 m. The combination of snow/firn samples and ground-penetrating radar profiles suggests that this accumulation pattern is persistent during the recent past. The recent accumulation history is reconstructed from internal radar reflectors using a firn densification model and shows strong interannual variations, but near constant mean values since 2002. Modeling of trajectories, based on accumulation and glacier geometry, results in an estimate of the depth/age relation close to the main divide. This region provides one of the most suitable locations for retrieving climate information with temporal high resolution for the last millennium, with a potential to cover most of the Holocene in less detail.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.1017/jog.2019.97
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2020
    detail.hit.zdb_id: 2140541-4
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  • 8
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    The secret life of ice sails
    Cambridge University Press (CUP) ; 2017
    In:  Journal of Glaciology Vol. 63, No. 242 ( 2017-12), p. 1049-1062
    Details
    In: Journal of Glaciology, Cambridge University Press (CUP), Vol. 63, No. 242 ( 2017-12), p. 1049-1062
    Abstract: We present the first dedicated study into the phenomenon of ice sails . These are clean ice structures that protrude from the surface of a small number of debris-covered glaciers and can grow to heights of over 25 m. We draw together what is known about them from the academic/exploration literature and then analyse imagery. We show here that ice sails can develop by one of two mechanisms, both of which require clean ice to become surrounded by debris-covered ice, where the debris layer is shallow enough for the ice beneath it to melt faster than the clean ice. Once formed, ice sails can persist for decades, in an apparently steady state, before debris layer thickening eventually causes a reversal in the relative melt rates and the ice sails decay to merge back with the surrounding glacier surface. We support our image-based analysis with a surface energy-balance model and show that it compares well with available observations from Baltoro Glacier in the Karakoram. A sensitivity analysis of the model is performed and confirms the results from our empirical study that ice sails require a relatively high evaporative heat flux and/or a relatively low sensible heat flux in order to exist.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.1017/jog.2017.72
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2017
    detail.hit.zdb_id: 2140541-4
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  • 9
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    Local surface mass-balance reconstruction from a tephra layer – a case study on the northern slope of Mýrdalsjökull, Iceland
    Cambridge University Press (CUP) ; 2017
    In:  Journal of Glaciology Vol. 63, No. 237 ( 2017-02), p. 79-87
    Details
    In: Journal of Glaciology, Cambridge University Press (CUP), Vol. 63, No. 237 ( 2017-02), p. 79-87
    Abstract: Most Icelandic glaciers show high-accumulation rates during winter and strong surface melting during summer. Although it is difficult to establish and maintain mass-balance programs on these glaciers, mass-balance series do exist for several of the ice caps (Björnsson and others, 2013). We make use of the frequent volcanic eruptions in Iceland, which cause widespread internal tephra layers in the ice caps, to reconstruct the surface mass balance (SMB) in the ablation zone. This method requires information about surface geometry and ice velocity, derived from remote-sensing information. In addition, the emergence angle of the tephra layer needs to be known. As a proof-of-concept, we utilize a prominent tephra layer of the Mýrdalsjökull Ice Cap to infer local SMB estimates in the ablation area back to 1988. Using tephra-layer outcrop locations across the glacier at different points in time it is possible to determine local mass changes (loss and redistribution) for a large part of the ablation zone, without the use of historic elevation models, which often are not available.
    Type of Medium: Online Resource
    ISSN: 0022-1430 , 1727-5652
    URL: Article
    DOI: 10.1017/jog.2016.119
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2017
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  • 10
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    Iterative Course Design in MOOCs: Evaluating a ProtoMOOC
    Cambridge University Press (CUP) ; 2019
    In:  Proceedings of the Design Society: International Conference on Engineering Design Vol. 1, No. 1 ( 2019-07), p. 539-548
    Details
    In: Proceedings of the Design Society: International Conference on Engineering Design, Cambridge University Press (CUP), Vol. 1, No. 1 ( 2019-07), p. 539-548
    Abstract: This paper describes an iterative approach to course design in an effort to improve the learner-centered conceptualization of Massive Open Online Courses (MOOCs). The research team built a (design research) MOOC prototype and used three measurement tools to gather user feedback. The authors categorized this feedback and translated it into 57 improvement tasks, which they implemented in the public version of the MOOC. They discuss the protoMOOC iteration approach, underline its applicability, and suggest it as a method for fellow MOOC designers.
    Type of Medium: Online Resource
    ISSN: 2220-4342
    URL: Article
    DOI: 10.1017/dsi.2019.58
    Language: English
    Publisher: Cambridge University Press (CUP)
    Publication Date: 2019
    detail.hit.zdb_id: 3053477-X
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