| 1. |
- Abdalla, H., et al.
(författare)
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A very-high-energy component deep in the gamma-ray burst afterglow
- 2019
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 575:7783, s. 464-467
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Tidskriftsartikel (refereegranskat)abstract
- Gamma-ray bursts (GRBs) are brief flashes of gamma-rays and are considered to be the most energetic explosive phenomena in the Universe(1). The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow-produced by the interaction between the ejected matter and the circumburst medium-slows down, and a gradual decrease in brightness is observed(2). GRBs typically emit most of their energy via.-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments(3). However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elusive(4). Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow-ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and gamma-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.
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| 4. |
- Sailer, Anna, et al.
(författare)
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A genome-wide association study in multiple system atrophy
- 2016
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Ingår i: Neurology. - 0028-3878. ; 87:15, s. 1591-1598
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To identify genetic variants that play a role in the pathogenesis of multiple system atrophy (MSA), we undertook a genome-wide association study (GWAS). Methods: We performed a GWAS with >5 million genotyped and imputed single nucleotide polymorphisms (SNPs) in 918 patients with MSA of European ancestry and 3,864 controls. MSA cases were collected from North American and European centers, one third of which were neuropathologically confirmed. Results: We found no significant loci after stringent multiple testing correction. A number of regions emerged as potentially interesting for follow-up at p < 1 × 10-6, including SNPs in the genes FBXO47, ELOVL7, EDN1, and MAPT. Contrary to previous reports, we found no association of the genes SNCA and COQ2 with MSA. Conclusions: We present a GWAS in MSA. We have identified several potentially interesting gene loci, including the MAPT locus, whose significance will have to be evaluated in a larger sample set. Common genetic variation in SNCA and COQ2 does not seem to be associated with MSA. In the future, additional samples of well-characterized patients with MSA will need to be collected to perform a larger MSA GWAS, but this initial study forms the basis for these next steps.
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| 6. |
- Pfabigan, DM, et al.
(författare)
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Event-related potentials in performance monitoring are influenced by the endogenous opioid system.
- 2015
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Ingår i: Neuropsychologia. - : Elsevier BV. - 0028-3932 .- 1873-3514. ; 77, s. 242-252
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Tidskriftsartikel (refereegranskat)abstract
- Recent research suggests that not only the dopamine neurotransmitter system but also the endogenous opioid system is involved in performance monitoring and the generation of prediction error signals. Heightened performance monitoring is also associated with psychopathology such as internalizing disorders. Therefore, the current study investigated the potential link between the functional opioid peptide prodynorphin (PDYN) 68 bp VNTR genetic polymorphism and neuronal correlates of performance monitoring. To this end, 47 healthy participants genotyped for this polymorphism, related to high-, intermediate-, and low-expression levels of PDYN, performed a choice-reaction task while their electroencephalogram (EEG) was recorded. On the behavioural level, no differences between the three PDYN groups could be observed. EEG data, however, showed significant differences. High PDYN expression individuals showed heightened neural error processing indicated by higher ERN amplitudes, compared to intermediate and low expression individuals. Later stages of error processing, indexed by late Pe amplitudes, and stimulus-driven conflict processing, indexed by N2 amplitudes, were not affected by PDYN genotype. The current results corroborate the notion of an indirect effect of endogenous opioids on performance monitoring, probably mediated by the mesencephalic dopamine system. Overall, enhanced ERN amplitudes suggest a hyper-active performance monitoring system in high PDYN expression individuals, and this might also be an indicator of a higher risk for internalizing disorders.
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| 7. |
- Strauss, Timmy, et al.
(författare)
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Touch aversion in patients with interpersonal traumatization
- 2019
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Ingår i: Depression and anxiety (Print). - : WILEY. - 1091-4269 .- 1520-6394. ; 36:7, s. 635-646
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Tidskriftsartikel (refereegranskat)abstract
- Background Interpersonal touch is a key aspect of human interaction and a usually very comforting experience. For patients suffering from posttraumatic stress disorders (PTSD) caused by interpersonal traumatization, such touch is affectively ambiguous. Methods In two studies, we investigated the experience and neural processing of various types of interpersonal and impersonal touch in patients as compared with healthy controls. Results Patients strongly disliked show, interpersonal skin-to-skin stroking, while controls appreciated this kind of touch. No group differences were observed for ratings of impersonal touch. Similarly, the neural activation differed between groups for interpersonal, but not for impersonal touch. The interpersonal touch aversion in patients was accompanied by enhanced blood-oxygen-level-dependent response in the superior temporal gyrus and by a pronounced reduction of response in the hippocampus. This reduction was significantly correlated to symptoms of negative alterations and arousal within the patients. Conclusion We interpret the hippocampal suppression as an attempt to control traumatic memories, evoked by interpersonal touch. This mechanism may maintain the aversion of interpersonal touch in patients with interpersonal trauma-related PTSD.
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