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- Holmgren, Christina M, et al.
(författare)
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Out-of-hospital cardiac arrest : Causes according to autopsy and electrocardiography - Analysis of 781 patients with neither hospital care nor prescribed medication during the preceding two years.
- 2020
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Ingår i: Resuscitation. - : Elsevier BV. - 0300-9572 .- 1873-1570. ; 150, s. 65-71
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: There is a knowledge gap regarding aetiology of and potential for predicting out-of-hospital cardiac arrest (OHCA) among individuals who are healthy before the event.AIM: To describe causes of OHCA and the potential for predicting OHCA in apparently healthy patients.METHODS: Patients were recruited from the Swedish Register of Cardiopulmonary Resuscitation from November 2007 to January 2011. Inclusion criteria were: OHCA with attempted CPR but neither dispensed prescription medication nor hospital care two years before the event The register includes the majority of patients suffering OHCA in Sweden where cardiopulmonary resuscitation (CPR) was attempted. Medication status was defined by linkage to the Swedish Prescribed Drug Register. Cause of death was assessed based on autopsy and the Swedish Cause of Death Register. Prediction of OHCA was attempted based on available electrocardiograms (ECG) before the OHCA event.RESULTS: Altogether 781 individuals (16% women) fulfilled the inclusion criteria. Survival to 30 days was 16%. Autopsy rate was 72%. Based on autopsy, 70% had a cardiovascular aetiology and 59% a cardiac aetiology. An ECG recording before the event was found in 23% of cases. The ECG was abnormal in 22% of them.CONCLUSION: Among OHCA victims who appeared to be healthy prior to the event, the cause was cardiovascular in the great majority according to autopsy findings. A minority had a preceding abnormal ECG that could have been helpful in avoiding the event.
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- Kubyshkina, Elena, 1990-
(författare)
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Ab initio modelling of interfaces in nanocomposites for high voltage insulation
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dielectric nanocomposite materials have been experimentally proven to have properties that are beneficial in applications for efficient energy transport. However, today there are still no empirical models or rules that can predict the performance of a certain combination of materials in the nanocomposite, and there are also no definitive explanations of their dielectric behavior. A deeper understanding of the phenomena behind these materials' response to an applied electric field can open new possibilities for improvement of the insulating properties of nanocomposites.The goal of this work is to locate the key processes that are responsible for dielectric performance. The methodology of the study is based on ab initio technology, that relies solely on the knowledge of chemical and structural composition of the material. In this work, the charge-related properties of nanocomposite interfaces are studied. The primary material of the study is chosen to be polyethylene-based composite with magnesium oxide nanoparticles.The impact of the nanoparticle crystal surface termination and its silane treatment on the electronic structure of the interface between MgO and polyethylene are investigated here. Moreover, the effects of presence of carboxyl defect and water molecule near the interface are considered in this work as well.Based on the calculated electronic structure data, a model for charge dynamics is proposed. The model explains mechanisms for conductivity and space charge reduction in nanocomposites, but also predicts an increase in thermal stress and susceptibility for chemical defects. It is suggested here that the suppression mechanisms for space charge and conductivity in nanocomposites are inherently unstable and can also accelerate material aging.
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- Stridh, Sara, et al.
(författare)
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Angiotensin converting enzyme inhibition blocks interstitial hyaluronan dissipation in the neonatal rat kidney via hyaluronan synthase 2 and hyaluronidase 1.
- 2011
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Ingår i: Matrix biology : journal of the International Society for Matrix Biology. - : Elsevier BV. - 1569-1802 .- 0945-053X. ; 30:1, s. 62-9
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Tidskriftsartikel (refereegranskat)abstract
- A functional renin-angiotensin system (RAS) is required for normal kidney development. Neonatal inhibition of the RAS in rats results in long-term pathological renal phenotype and causes hyaluronan (HA), which is involved in morphogenesis and inflammation, to accumulate. To elucidate the mechanisms, intrarenal HA content was followed during neonatal completion of nephrogenesis with or without angiotensin converting enzyme inhibition (ACEI) together with mRNA expression of hyaluronan synthases (HAS), hyaluronidases (Hyal), urinary hyaluronidase activity and cortical lymphatic vessels, which facilitate the drainage of HA from the tissue. In 6-8days old control rats cortical HA content was high and reduced by 93% on days 10-21, reaching adult low levels. Medullary HA content was high on days 6-8 and then reduced by 85% to 12-fold above cortical levels at day 21. In neonatally ACEI-treated rats the reduction in HA was abolished. Temporal expression of HAS2 corresponded with the reduction in HA content in the normal kidney. In ACEI-treated animals cortical HAS2 remained twice the expression of controls. Medullary Hyal1 increased in controls but decreased in ACEI-treated animals. Urine hyaluronidase activity decreased with time in control animals while in ACEI-treated animals it was initially 50% lower and did not change over time. Cells expressing the lymphatic endothelial mucoprotein podoplanin in ACEI-treated animals were increased 18-fold compared to controls suggesting compensation. In conclusion, the high renal HA content is rapidly reduced due to reduced HAS2 and increased Hyal1 mRNA expressions. Normal angiotensin II function is crucial for inducing these changes. Due to the extreme water-attracting and pro-inflammatory properties of HA, accumulation in the neonatally ACEI-treated kidneys may partly explain the pathological renal phenotype of the adult kidney, which include reduced urinary concentration ability and tubulointerstitial inflammation.
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- Åstrand, Elaine, et al.
(författare)
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Comparison of Classifiers for Decoding Sensory and Cognitive Information from Prefrontal Neuronal Populations.
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. 1-14
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Tidskriftsartikel (refereegranskat)abstract
- Decoding neuronal information is important in neuroscience, both as a basic means to understand how neuronal activity is related to cerebral function and as a processing stage in driving neuroprosthetic effectors. Here, we compare the readout performance of six commonly usedclassifiers at decoding two different variables encoded by the spiking activity of the non-human primate frontal eye fields (FEF): the spatial position of a visual cue, and the instructed orientation of the animal's attention. While the first variable is exogenously driven by the environment, the second variable corresponds to the interpretation of the instruction conveyed by the cue; it is endogenously driven and corresponds to the output of internalcognitive operations performed on the visual attributes of the cue. These two variables were decoded using either a regularized optimal linear estimator in its explicit formulation, an optimal linear artificial neural network estimator, a non-linear artificial neural network estimator, a non-linear naïve Bayesian estimator, a non-linear Reservoir recurrent network classifier or a non-linear Support Vector Machine classifier. Our results suggest that endogenous information such as the orientation of attention can be decoded from the FEF with the same accuracy as exogenous visualinformation. All classifiers did not behave equally in the face of population size and heterogeneity, the available training and testing trials, the subject's behavior and the temporal structure of the variable of interest. In most situations, the regularized optimal linear estimator and the non-linear Support Vector Machine classifiers outperformed the other tested decoders.
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- Åstrand, Elaine, et al.
(författare)
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Differential dynamics of spatial attention, position, and color coding within the parietofrontal network
- 2015
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Ingår i: Journal of Neuroscience. - United States. - 0270-6474 .- 1529-2401. ; 35:7, s. 3174-3189
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Tidskriftsartikel (refereegranskat)abstract
- Despite an ever growing knowledge on howparietal and prefrontal neurons encode low-level spatial and color information or higher-level information, such as spatial attention, an understanding of how these cortical regions process neuronal information at the population level is still missing. A simple assumption would be that the function and temporal response profiles of these neuronal populations match that of its constituting individual cells. However, several recent studies suggest that this is not necessarily the case and that the single-cell approach overlooks dynamic changes in how information is distributed over the neuronal population. Here, we use a time-resolved population pattern analysis to explore how spatialposition, spatial attention and color information are differentially encoded and maintained in the macaque monkey prefrontal (frontal eye fields) and parietal cortex (lateral intraparietal area). Overall, our work brings about three novel observations. First, we show that parietal and prefrontal populations operate in two distinct population regimens for the encoding of sensory and cognitive information: a stationary mode and a dynamic mode. Second, we show that the temporal dynamics of a heterogeneous neuronal population brings about complementary information to that of its functional subpopulations. Thus, both need to be investigated in parallel. Last, we show that identifying the neuronal configuration in which a neuronal population encodes given information can serve to reveal this same information in a different context. All together, this work challenges common views on neural coding in the parietofrontal network.
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- Åstrand, Elaine, et al.
(författare)
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Selective visual attention to drive cognitive brain-machine interfaces : from concepts to neurofeedback and rehabilitation applications
- 2014
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Ingår i: Frontiers in Systems Neuroscience. - Switzerland : Frontiers Media SA. - 1662-5137. ; 8:144, s. 144-160
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Tidskriftsartikel (refereegranskat)abstract
- Brain-machine interfaces (BMIs) using motor cortical activity to drive an external effector like a screen cursor or a robotic arm have seen enormous success and proven their great rehabilitation potential. An emerging parallel effort is now directed to BMIs controlled by endogenouscognitive activity, also called cognitive BMIs. While more challenging, this approach opens new dimensions to the rehabilitation of cognitivedisorders. In the present work, we focus on BMIs driven by visuospatial attention signals and we provide a critical review of these studies in the light of the accumulated knowledge about the psychophysics, anatomy, and neurophysiology of visual spatial attention. Importantly, we provide a unique comparative overview of the several studies, ranging from non-invasive to invasive human and non-human primates studies, that decodeattention-related information from ongoing neuronal activity. We discuss these studies in the light of the challenges attention-driven cognitive BMIs have to face. In a second part of the review, we discuss past and current attention-based neurofeedback studies, describing both the covert effects of neurofeedback onto neuronal activity and its overt behavioral effects. Importantly, we compare neurofeedback studies based on the amplitude of cortical activity to studies based on the enhancement of cortical information content. Last, we discuss several lines of future research and applications for attention-driven cognitive brain-computer interfaces (BCIs), including the rehabilitation of cognitive deficits, restored communication in locked in patients, and open-field applications for enhanced cognition in normal subjects. The core motivation of this work is the key idea that the improvement of current cognitive BMIs for therapeutic and open field applications needs to be grounded in a proper interdisciplinary understanding of the physiology of the cognitive function of interest, be it spatial attention, working memory or any other cognitive signal.
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