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- Lutzenkirchen, J., et al.
(författare)
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The surface chemistry of sapphire-c: A literature review and a study on various factors influencing its IEP
- 2018
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 251, s. 1-25
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Forskningsöversikt (refereegranskat)abstract
- A wide range of isoelectric points (IEPs) has been reported in the literature for sapphire-c (alpha-alumina), also referred to as basal plane, (001) or (0001), single crystals. Interestingly, the available data suggest that the variation of IEPs is comparable to the range of IEPs encountered for particles, although single crystals should be much better defined in terms of surface structure. One explanation for the range of IEPs might be the obvious danger of contaminating the small surface areas of single crystal samples while exposing them to comparatively large solution reservoirs. Literature suggests that factors like origin of the sample, sample treatment or the method of investigation all have an influence on the surfaces and it is difficult to clearly separate the respective, individual effects. In the present study, we investigate cause-effect relationships to better understand the individual effects. The reference IEP of our samples is between 4 and 4.5. High temperature treatment tends to decrease the IEP of sapphire-c as does UV treatment. Increasing the initial miscut (i.e. the divergence from the expected orientation of the crystal) tends to increase the IEP as does plasma cleaning, which can be understood assuming that the surfaces have become less hydrophobic due to the presence of more and/or larger steps with increasing miscut or due to amorphisation of the surface caused by plasma cleaning. Pre-treatment at very high pH caused an increase in the IEP. Surface treatments that led to IEPs different from the stable value of reference samples typically resulted in surfaces that were strongly affected by subsequent exposure to water. The streaming potential data appear to relax to the reference sample behavior after a period of time of water exposure. Combination of the zeta potential measurements with AFM investigations support the idea that atomically smooth surfaces exhibit lower IEPs, while rougher surfaces (roughness on the order of nanometers) result in higher IEPs compared to reference samples. Two supplementary investigations resulted in either surprising or ambiguous results. On very rough surfaces (roughness on the order of micrometers) the IEP lowered compared to the reference sample with nanometer-scale roughness and transient behavior of the rough surfaces was observed. Furthermore, differences in the IEP as obtained from streaming potential and static colloid adhesion measurements may suggest that hydrodynamics play a role in streaming potential experiments. We finally relate surface diffraction data from previous studies to possible interpretations of our electroldnetic data to corroborate the presence of a water film that can explain the low IEP. Calculations show that the surface diffraction data are in line with the presence of a water film, however, they do not allow to unambiguously resolve critical features of this film which might explain the observed surface chemical characteristics like the dangling OH-bond reported in sum frequency generation studies. A broad literature review on properties of related surfaces shows that the presence of such water films could in many cases affect the interfacial properties. Persistence or not of the water film can be crucial. The presence of the water film can in principle affect important processes like ice-nucleation, wetting behavior, electric charging, etc. (C) 2017 Elsevier B.V. All rights reserved.
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- Welling, D. T., et al.
(författare)
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Recommendations for Next-Generation Ground Magnetic Perturbation Validation
- 2018
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Ingår i: Space Weather. - 1542-7390. ; 16:12, s. 1912-1920
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Tidskriftsartikel (refereegranskat)abstract
- Data-model validation of ground magnetic perturbation forecasts, specifically of the time rate of change of surface magnetic field, dB/dt, is a critical task for model development and for mitigation of geomagnetically induced current effects. While a current, community-accepted standard for dB/dt validation exists (Pulkkinen et al., 2013), it has several limitations that prevent more complete understanding of model capability. This work presents recommendations from the International Forum for Space Weather Capabilities Assessment Ground Magnetic Perturbation Working Team for creating a next-generation validation suite. Four recommendations are made to address the existing suite: greatly expand the number of ground observatories used, expand the number of events included in the suite from six to eight, generate metrics as a function of magnetic local time, and generate metrics as a function of activity type. For each of these, implementation details are explored. Limitations and future considerations are also discussed.
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- Claesson, A., et al.
(författare)
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Unmanned aerial vehicles (drones) in out-of-hospital-cardiac-arrest
- 2016
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : BioMed Central (BMC). - 1757-7241. ; 24:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The use of an automated external defibrillator (AED) prior to EMS arrival can increase 30-day survival in out-of-hospital cardiac arrest (OHCA) significantly. Drones or unmanned aerial vehicles (UAV) can fly with high velocity and potentially transport devices such as AEDs to the site of OHCAs. The aim of this explorative study was to investigate the feasibility of a drone system in decreasing response time and delivering an AED. Methods: Data of Global Positioning System (GPS) coordinates from historical OHCA in Stockholm County was used in a model using a Geographic Information System (GIS) to find suitable placements and visualize response times for the use of an AED equipped drone. Two different geographical models, urban and rural, were calculated using a multi-criteria evaluation (MCE) model. Test-flights with an AED were performed on these locations in rural areas. Results: In total, based on 3,165 retrospective OHCAs in Stockholm County between 2006-2013, twenty locations were identified for the potential placement of a drone. In a GIS-simulated model of urban OHCA, the drone arrived before EMS in 32 % of cases, and the mean amount of time saved was 1.5 min. In rural OHCA the drone arrived before EMS in 93 % of cases with a mean amount of time saved of 19 min. In these rural locations during (n = 13) test flights, latch-release of the AED from low altitude (3-4 m) or landing the drone on flat ground were the safest ways to deliver an AED to the bystander and were superior to parachute release. Discussion: The difference in response time for EMS between urban and rural areas is substantial, as is the possible amount of time saved using this UAV-system. However, yet another technical device needs to fit into the chain of survival. We know nothing of how productive or even counterproductive this system might be in clinical reality. Conclusions: To use drones in rural areas to deliver an AED in OHCA may be safe and feasible. Suitable placement of drone systems can be designed by using GIS models. The use of an AED equipped drone may have the potential to reduce time to defibrillation in OHCA.
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- Fredman, D., et al.
(författare)
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Expanding the first link in the chain of survival – Experiences from dispatcher referral of callers to AED locations
- 2016
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Ingår i: Resuscitation. - : Elsevier. - 0300-9572 .- 1873-1570. ; 107, s. 129-134
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Early use of automated external defibrillators (AED) increases survival in cases of out-of-hospital cardiac arrest (OHCA). Dispatchers play important roles in identifying OHCA, dispatching ambulances and providing callers with telephone-assisted cardiopulmonary resuscitation. Guidelines recommend that AED registries be linked to dispatch centres as tools to refer callers to nearby AED. Aim The aim of this study was to investigate to what extent dispatchers, when provided with a tool to display AED locations and accessibility, referred callers to nearby AED. Methods An application providing real-time visualization of AED locations and accessibility was implemented at four dispatch centres in Sweden. Dispatchers were instructed to refer callers to nearby AED when OHCA was suspected. Such cases were prospectively collected, and geographic information systems were used to identify those located ≤100 m from an AED. Audio recordings of emergency calls were assessed to evaluate the AED referral rate. Results Between February and August 2014, 3009 suspected OHCA calls were received. In 6.6% of those calls (200/3009), an AED was ≤100 m from the suspected OHCA. The AED was accessible and the caller was not alone on scene in 24% (47/200) of these cases. In two of those 47 cases (4.3%), the dispatcher referred the caller to the AED. Conclusion Despite a tool for dispatchers to refer callers to a nearby AED, referral was rare. Only a minority of the suspected OHCA cases occurred ≤100 m from an AED. We identified AED accessibility and callers being alone on scene as obstacles for AED referral.
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- Fredman, David, et al.
(författare)
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Objective classification and comparison of OHCA and AED locations using geographic information systems
- 2015
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Ingår i: Resuscitation. - : Elsevier BV. - 0300-9572 .- 1873-1570. ; 96, s. 21-21
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Tidskriftsartikel (refereegranskat)abstract
- The Utstein registry template stress recording of out-of-hospital cardiac arrest (OHCA) location and suggest eight data options with additional subcategories. The subjectivity in categorization of OHCA locations by emergency medical services (EMS) makes objective regional and international comparisons hard.
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- Held, Claes, et al.
(författare)
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Clinical outcomes and management associated with major bleeding in patients with atrial fibrillation treated with apixaban or warfarin : insights from the ARISTOTLE trial
- 2015
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 36:20, s. 1264-1272
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Tidskriftsartikel (refereegranskat)abstract
- Aim In the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) trial, apixaban compared with warfarin reduced the risk of stroke, major bleed, and death in patients with atrial fibrillation. In this ancillary study, we evaluated clinical consequences of major bleeds, as well as management and treatment effects of warfarin vs. apixaban.Methods and results Major International Society on Thrombosis and Haemostasis bleeding was defined as overt bleeding accompanied by a decrease in haemoglobin (Hb) of ≥2 g/dL or transfusion of ≥2 units of packed red cells, occurring at a critical site or resulting in death. Time to event [death, ischaemic stroke, or myocardial infarction (MI)] was evaluated by Cox regression models. The excess risk associated with bleeding was evaluated by separate time-dependent indicators for intracranial (ICH) and non-intracranial haemorrhage. Major bleeding occurred in 848 individuals (4.7%), of whom 126 (14.9%) died within 30 days. Of 176 patients with an ICH, 76 (43.2%) died, and of the 695 patients with major non-ICH, 64 (9.2%) died within 30 days of the bleeding. The risk of death, ischaemic stroke, or MI was increased roughly 12-fold after a major non-ICH bleeding event within 30 days. Corresponding risk of death following an ICH was markedly increased, with HR 121.5 (95% CI 91.3–161.8) as was stroke or MI with HR 21.95 (95% CI 9.88–48.81), respectively. Among patients with major bleeds, 20.8% received vitamin K and/or related medications (fresh frozen plasma, coagulation factors, factor VIIa) to stop bleeding within 3 days, and 37% received blood transfusion. There was no interaction between apixaban and warfarin and major bleeding on the risk of death, stroke, or MI.Conclusion Major bleeding was associated with substantially increased risk of death, ischaemic stroke, or MI, especially following ICH, and this risk was similarly elevated regardless of treatment with apixaban or warfarin. These results underscore the importance of preventing bleeding in anti-coagulated patients.
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- Hesser, Hugo, 1982-, et al.
(författare)
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Preventing intimate partner violence via the Internet : A randomized controlled trial of emotion-regulation and conflict-management training for individuals with aggression problems
- 2017
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Ingår i: Clinical Psychology and Psychotherapy. - : John Wiley & Sons. - 1063-3995 .- 1099-0879. ; 24:5, s. 1163-1177
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this randomized controlled trial was to investigate the effect of an Internet-delivered cognitive behaviour therapy (iCBT), which incorporated emotion-regulation and conflict-resolution techniques, on intimate partner violence (IPV). Another aim was to test the theoretical underpinnings of the treatment model using mediation analysis.Method: Sixty-five participants with aggression problems in intimate adult relationships were recruited from the community and were randomly assigned to iCBT or to a monitored waitlist control. Participants were assessed with standardized self-report measures of IPV or aggression (Multidimensional Measure of Emotional Abuse, Revised Conflict Tactics Scale, and Aggression Questionnaire), relationship quality (Dyadic Adjustment Scale), anxiety or depression symptomatology (Patient Health Questionnaire; Generalized Anxiety Disorder Screener), at pretreatment, posttreatment (8weeks), and 1-year follow-up. Process variables (subscales of Dysfunctional and Emotional Regulation Scale and Anger Rumination Scale) were assessed weekly over the active treatment phase.Results: Robust linear regression analysis of all randomized participants showed significant treatment effects on emotional abuse relative to control at postassessment. Mediation analysis using growth curve modeling revealed that the treatment effect was partially mediated by changes in emotion-regulation ability. Controlled effects on secondary outcomes were also observed. Analyses of uncontrolled effects indicted that gains on IPV were maintained at 1-year follow-up.Conclusions: iCBT focusing on enhancing conflict-resolution skills and emotion-regulation ability has the potential to reduce IPV among self-recruited individuals with mild forms of abusive behaviour in intimate relationships. Emotion-regulation ability is potentially a key therapeutic process of change.Key Practitioner Message:Internet-delivered clinician-guided cognitive behaviour therapy is a viable treatment option for reducing intimate partner violence among self-recruited individuals with mild forms of abusive behaviour.For persons who display patterns of frequent and severe violence, other treatments are most likely needed.Emotion-regulation training is potentially a key therapeutic component that ought to be incorporated in interventions targeting IPV.
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