| 1. |
- Kanai, Y., et al.
(författare)
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Beam test of a prototype phoswich detector assembly for the PoGOLite astronomical soft gamma-ray polarimeter
- 2007
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 570:1, s. 61-71
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Tidskriftsartikel (refereegranskat)abstract
- We report about the beam test on a prototype of the balloon-based astronomical soft gamma-ray polarimeter, PoGOLite (Polarized Gamma-ray Observer-Light Version) conducted at KEK Photon Factory, a synchrotron radiation facility in Japan. The synchrotron beam was set at 30, 50, and 70 keV and its polarization was monitored by a calibrated polarimeter. The goal of the experiment was to validate the flight design of the polarimeter. PoGOLite is designed to measure polarization by detecting a Compton scattering and the subsequent photo-absorption in an array of 217 well-type phoswich detector cells (PDCs). The test setup included a first flight model PDC and a front-end electronics to select and reconstruct valid Compton scattering events. The experiment has verified that the flight PDC can detect recoil electrons and select valid Compton scattering events down to 30 keV from background. The measure azimuthal modulations (34.4%, 35.8% and 37.2% at 30, 50, and 70 keV, respectively) agreed within 10% (relative) with the predictions by Geant4 implemented with dependence on the initial and final photon polarizations.
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| 2. |
- Perez-Torres, M. A., et al.
(författare)
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CONSTRAINTS ON THE PROGENITOR SYSTEM AND THE ENVIRONS OF SN 2014J FROM DEEP RADIO OBSERVATIONS
- 2014
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Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 792:1, s. 38-
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Tidskriftsartikel (refereegranskat)abstract
- We report deep EVN and eMERLIN observations of the Type Ia SN 2014J in the nearby galaxy M82. Our observations represent, together with JVLA observations of SNe 2011fe and 2014J, the most sensitive radio studies of Type Ia SNe ever. By combining data and a proper modeling of the radio emission, we constrain the mass-loss rate from the progenitor system of SN 2014J to (M) over dot less than or similar to 7.0 x 10(-10) M yr(-1) (for a wind speed of 100 km s(-1)). If the medium around the supernova is uniform, then n(ISM) less than or similar to 1.3 cm(-3), which is the most stringent limit for the (uniform) density around a Type Ia SN. Our deep upper limits favor a double-degenerate (DD) scenario-involving two WD stars-for the progenitor system of SN 2014J, as such systems have less circumstellar gas than our upper limits. By contrast, most single-degenerate (SD) scenarios, i.e., the wide family of progenitor systems where a red giant, main-sequence, or sub-giant star donates mass to an exploding WD, are ruled out by our observations. (While completing our work, we noticed that a paper by Margutti et al. was submitted to The Astrophysical Journal. From a non-detection of X-ray emission from SN 2014J, the authors obtain limits of (M) over dot less than or similar to 1.2 x 10(-9) M-circle dot yr(-1) (for a wind speed of 100 km s(-1)) and n(ISM) less than or similar to 3.5 cm(-3), for the rho proportional to r(-2) wind and constant density cases, respectively. As these limits are less constraining than ours, the findings by Margutti et al. do not alter our conclusions. The X-ray results are, however, important to rule out free-free and synchrotron self-absorption as a reason for the radio non-detections.) Our estimates on the limits on the gas density surrounding SN2011fe, using the flux density limits from Chomiuk et al., agree well with their results. Although we discuss the possibilities of an SD scenario passing observational tests, as well as uncertainties in the modeling of the radio emission, the evidence from SNe 2011fe and 2014J points in the direction of a DD scenario for both.
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| 3. |
- Axelsson, Magnus, et al.
(författare)
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Measuring energy dependent polarization in soft γ-rays using Compton scattering in PoGOLite
- 2007
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Ingår i: Astroparticle Physics. - : Elsevier BV. - 0927-6505. ; 28:3, s. 327-337
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Tidskriftsartikel (refereegranskat)abstract
- Linear polarization in X- and γ-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper, we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25–100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 h were simulated, corresponding to a standard and a long duration flight, respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.
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| 4. |
- Lind, J., et al.
(författare)
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Parietal cortex activation predicts longitudinal memory decline in APOE ε4 carriers.
- 2006
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Ingår i: NeuroReport. ; :17, s. 1683-1686
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Apolipoprotein E-epsilon 4 is the main known genetic risk factor for Alzheimer’s disease. Functional abnormalities in the parietal cortex have been reported for Alzheimer’s disease patients and also for those at risk. Hence, a critical question is whether measurements of parietal cortex integrity may predict negative outcome among at- risk persons. We studied nondemented apolipo-protein E-epsilon 4 carriers and found a significant relationship between parietal blood-oxygen-level-dependent functional magnetic resonance imaging response during a word categorization task and subsequent episodic memory performance. Thus, the results show that parietal cortex alterations predict memory decline in nondemented apolipoprotein E-epsilon 4 carriers, and hence likely progression to Alzheimer’s disease.
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| 5. |
- Persson, J, et al.
(författare)
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Altered brain white-matter integrity in non-demented carriers of the APOE ε4 allele: A risk for Alzheimer’s disease.
- 2006
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Ingår i: Neurology. - : Ovid Technologies (Wolters Kluwer Health). - 0028-3878 .- 1526-632X. ; 66:7, s. 1029-1033
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that polymorphisms of the apolipoprotein E (APOE) represent genetic risk factors for dementia and for cognitive impairment in the elderly. The neural mechanisms by which these genetic variations influence behavioral performance or clinical severity are not well understood. We used diffusion tensor imaging to investigate ultrastructural properties in brain white-matter to detect pathological processes that modify tissue integrity. Sixty participants were included in the study of which 30 were homozygous for the APOE ε3 allele, 10 were homozygous for the APOE ε4 allele, and 20 had the APOE ε34 allele combination. All individuals were non-demented, and the groups were matched on demographic variables and cognitive performance. The results showed a decline in fractional anisotropy, a marker for white-matter integrity, in the posterior corpus callosum of ε4 carriers compared to non-carriers. Additional sites of altered white-matter integrity included the medial temporal lobe. Conclusions: Although the mechanism underlying vulnerability of white matter tracts in APOE ε4 carriers is still unknown, our findings suggest that increased genetic risk for developing AD is associated with changes in microscopic white-matter integrity well before the onset of dementia.
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| 6. |
- Karshikoff, B., et al.
(författare)
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LPS increases pain sensitivity by decreased pain inhibition and increased insular activation
- 2015
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Ingår i: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 49, s. e1-e1
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Tidskriftsartikel (refereegranskat)abstract
- We have shown that women are more prone to developing LPS-induced pain sensitivity than men, and that the descending endogenous pain inhibition is disrupted in women during experimental systemic inflammation. The aim of the present study was to investigate some of the central neural mechanisms underlying our previous findings. 51 participants (29 women) were injected with 0.6 ng/kg LPS or saline and went through a thumb-pressure pain fMRI paradigm 2 h after injection. As hypothesized, the subjects injected with LPS had decreased activity in the ventromedial prefrontal cortex and rostral anterior cingulate cortex (rACC), areas involved in descending pain inhibition. In addition, the LPS group had higher activity in the anterior insula, an area involved in medial/affective pain processing and interoception. These effects were not sex dependent. However, the male participants had overall stronger descending pain inhibition, reflected as a stronger rACC activity compared to women. It is possible that the more robust activation of descending pain inhibition rendered the men more resistant to the immune provocation, which may explain previously seen sex differences in LPS-induced pain sensitivity. Our findings give an indication to how the pain matrix is affected during a sickness response. The results strengthen the proposed link between systemic inflammation and weakened pain regulation in chronic pain disorders, and offers a possible mechanism underlying the female predominance in chronic pain disorders.
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| 7. |
- Karshikoff, B., et al.
(författare)
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Modality and sex differences in pain sensitivity during human endotoxemia
- 2014
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Ingår i: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 46, s. 35-43
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Tidskriftsartikel (refereegranskat)abstract
- Systemic inflammation can induce pain hypersensitivity in animal and human experimental models, and has been proposed to be central in clinical pain conditions. Women are overrepresented in many chronic pain conditions, but experimental studies on sex differences in pain regulation during systemic inflammation are still scarce. In two randomized and double blind placebo controlled experiments, we used low doses of lipopolysaccharide (LPS) as an experimental model of systemic inflammation. The first study employed 0.8ng/kg LPS in a within-subject design of 8 individuals (1 woman), and the second study 0.6ng/kg LPS in a between-subject design of 52 participants (29 women). We investigated the effect on (a) pressure, heat, and cold pain thresholds, (b) suprathreshold noxious heat and cold sensitivity, and (c) conditioned pain modulation (CPM), and differences between men and women. LPS induced significantly lower pressure pain thresholds as compared to placebo (mean change with the 0.8ng/kg dose being -64±30kPa P=.04; with the 0.6ng/kg dose -58±55kPa, P<.01, compared to before injection), whereas heat and cold pain thresholds remained unaffected (P's>.70). Suprathreshold noxious pain was not affected by LPS in men (P's⩾.15). However, LPS made women rated suprathreshold noxious heat stimuli as more painful (P=.01), and showed a tendency to rate noxious cold pain as more painful (P=.06) as compared to placebo. Furthermore, LPS impaired conditioned pain modulation, a measure of endogenous pain inhibition, but this effect was also restricted to women (P<.01, for men P=.27). Pain sensitivity correlated positively with plasma IL-6 and IL-8 levels. The results show that inflammation more strongly affects deep pain, rather than cutaneous pain, and suggest that women's pain perception and modulation is more sensitive to immune activation than men's.
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| 8. |
- Karshikoff, Bianka, et al.
(författare)
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Why sickness hurts : A central mechanism for pain induced by peripheral inflammation
- 2016
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Ingår i: Brain, behavior, and immunity. - : Elsevier BV. - 0889-1591 .- 1090-2139. ; 57, s. 38-46
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Tidskriftsartikel (refereegranskat)abstract
- Low-grade systemic inflammation has been implicated in chronic pain, as well as in comorbid diseases like depression and fatigue. We have previously shown that women's pain perception and regulation is more affected by systemic inflammation than that of men. Here we investigated the neural substrates underlying these effects using an fMRI paradigm previously employed in a clinical population. Fifty-one participants (29 women) were injected with 0.6ng/kg lipopolysaccharide (LPS) or saline to induce a peripheral inflammatory response. The subjects were then tested with a pressure pain fMRI paradigm designed to capture descending pain inhibitory activity 2h after injection, and blood was sampled for cytokine analysis. The subjects injected with LPS became more pain sensitive compared to the placebo group, and the heightened pain sensitivity was paralleled by decreased activity in the ventrolateral prefrontal cortex and the rostral anterior cingulate cortex (rACC) compared to placebo; areas involved in descending pain regulation. The LPS group also had higher activity in the anterior insular cortex, an area underpinning affective and interoceptive pain processing. Women displayed overall less pain-evoked rACC activity compared to men, which may have rendered women less resilient to immune provocation, possibly explaining sex differences in LPS-induced pain sensitivity. Our findings elucidate the pain-related brain circuits affected by experimental peripheral inflammation, strengthening the theoretical link between systemic inflammation and weakened pain regulation in chronic pain disorders. The results further suggest a possible mechanism underlying the female predominance in many chronic pain disorders.
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| 9. |
- Kodal, Arne, et al.
(författare)
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Long-term effectiveness of cognitive behavioral therapy for youth with anxiety disorders
- 2018
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Ingår i: Journal of Anxiety Disorders. - : Elsevier BV. - 0887-6185 .- 1873-7897. ; 53, s. 58-67
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive behavioral therapy (CBT) has demonstrated favorable long-term outcomes in youth with anxiety disorders in efficacy trials. However, long-term outcomes of CBT delivered in a community setting are uncertain. This study examined the long-term outcomes of individual (ICBT) and group CBT (GCBT) in youth with anxiety disorders treated in community mental health clinics. A total of 139 youth (mean age at assessment 15.5 years, range 11-21 years) with a principal diagnosis of separation anxiety disorder (SAD), social anxiety disorder (SOP), and/or generalized anxiety disorder (GAD) were evaluated, on average, 3.9 years post-treatment (range 2.2-5.9 years). Outcomes included loss of all inclusion anxiety diagnoses, loss of the principal anxiety diagnosis and changes in youth- and parent-rated youth anxiety symptoms. At long-term follow-up, there was loss of all inclusion anxiety diagnoses in 53%, loss of the principal anxiety diagnosis in 63% of participants as well as significant reductions in all anxiety symptom measures. No statistical significant differences in outcome were obtained between ICBT and GCBT. Participants with a principal diagnosis of SOP had lower odds for recovery, compared to those with a principal diagnosis of SAD or GAD. In conclusion, outcomes of CBT for youth anxiety disorders delivered in community mental health clinics were improved at nearly 4 years post-treatment, and recovery rates at long-term follow-up were similar to efficacy trials.
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| 10. |
- Kodal, Arne, et al.
(författare)
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Predictors of long-term outcome of CBT for youth with anxiety disorders treated in community clinics
- 2018
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Ingår i: Journal of Anxiety Disorders. - : Elsevier BV. - 0887-6185 .- 1873-7897. ; 59, s. 53-63
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Tidskriftsartikel (refereegranskat)abstract
- Cognitive behavioral therapy (CBT) has proven long-term effects in youth with anxiety disorders. However, only a few studies have examined predictors of long-term outcomes of CBT treatment. The present study investigated possible predictors of long-term treatment outcomes in youth with mixed anxiety disorders treated in community mental health clinics. A total of 139 youth (mean age at assessment 15.5 years, range 11–21 years) with a principal diagnosis of separation anxiety disorder, social anxiety disorder, and/or generalized anxiety disorder were evaluated a mean of 3.9 years post-treatment (range 2.2–5.9 years). Outcomes were loss of all inclusion anxiety diagnoses, loss of the principal inclusion anxiety diagnosis, and changes in youth- and parent-rated youth anxiety symptoms. Predictors encompassed youth, parent and demographic factors, and post-treatment recovery. The most consistent finding was that low family social class predicted poorer outcomes. Higher treatment motivation was associated with better outcome whereas a diagnosis of social anxiety was associated with poorer outcome. Identified predictors extend on previous findings from efficacy trials, and the results indicate a need for more specific treatment protocols.
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