| 1. |
- Algaba, Juan-Carlos, et al.
(författare)
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Broadband Multi-wavelength Properties of M87 during the 2017 Event Horizon Telescope Campaign
- 2021
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 911:1
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Forskningsöversikt (refereegranskat)abstract
- In 2017, the Event Horizon Telescope (EHT) Collaboration succeeded in capturing the first direct image of the center of the M87 galaxy. The asymmetric ring morphology and size are consistent with theoretical expectations for a weakly accreting supermassive black hole of mass ∼6.5 × 109 M o˙. The EHTC also partnered with several international facilities in space and on the ground, to arrange an extensive, quasi-simultaneous multi-wavelength campaign. This Letter presents the results and analysis of this campaign, as well as the multi-wavelength data as a legacy data repository. We captured M87 in a historically low state, and the core flux dominates over HST-1 at high energies, making it possible to combine core flux constraints with the more spatially precise very long baseline interferometry data. We present the most complete simultaneous multi-wavelength spectrum of the active nucleus to date, and discuss the complexity and caveats of combining data from different spatial scales into one broadband spectrum. We apply two heuristic, isotropic leptonic single-zone models to provide insight into the basic source properties, but conclude that a structured jet is necessary to explain M87's spectrum. We can exclude that the simultaneous γ-ray emission is produced via inverse Compton emission in the same region producing the EHT mm-band emission, and further conclude that the γ-rays can only be produced in the inner jets (inward of HST-1) if there are strongly particle-dominated regions. Direct synchrotron emission from accelerated protons and secondaries cannot yet be excluded.
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| 2. |
- Fietze, I., et al.
(författare)
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Management of obstructive sleep apnea in Europe-A 10-year follow-up
- 2022
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Ingår i: Sleep Medicine. - : Elsevier BV. - 1389-9457. ; 97, s. 64-72
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Tidskriftsartikel (refereegranskat)abstract
- Objective: In 2010, a questionnaire-based study on obstructive sleep apnea (OSA) management in Europe identified differences regarding reimbursement, sleep specialist qualification, and titration procedures. Now, 10 years later, a follow-up study was conducted as part of the ESADA (European Sleep Apnea Database) network to explore the development of OSA management over time.Methods: The 2010 questionnaire including questions on sleep diagnostic, reimbursement, treatment, and certification was updated with questions on telemedicine and distributed to European Sleep Centers to reflect European OSA management practice.Results: 26 countries (36 sleep centers) participated, representing 20 ESADA and 6 non-ESADA countries. All 21 countries from the 2010 survey participated. In 2010, OSA diagnostic procedures were performed mainly by specialized physicians (86%), whereas now mainly by certified sleep specialists and specialized physicians (69%). Treatment and titration procedures are currently quite homogenous, with a strong trend towards more Autotitrating Positive Airway Pressure treatment (in hospital 73%, at home 62%). From 2010 to 2020, home sleep apnea testing use increased (76%-89%) and polysomnography as sole diagnostic procedure decreased (24%-12%). Availability of a sleep specialist qualification increased (52%-65%) as well as the number of certified polysomnography scorers (certified physicians: 36%-79%; certified technicians: 20%-62%). Telemedicine, not surveyed in 2010, is now in 2020 used in diagnostics (8%), treatment (50%), and follow-up (73%). Conclusion: In the past decade, formal qualification of sleep center personnel increased, OSA diagnostic and treatment procedures shifted towards a more automatic approach, and telemedicine became more prominent.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 3. |
- Gunduz, C., et al.
(författare)
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Hyperlipidaemia prevalence and cholesterol control in obstructive sleep apnoea: Data from the European sleep apnea database (ESADA)
- 2019
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 286:6, s. 676-688
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Tidskriftsartikel (refereegranskat)abstract
- Background and objective Obstructive sleep apnoea (OSA) and hyperlipidaemia are independent risk factors for cardiovascular disease. This study investigates the association between OSA and prevalence of hyperlipidaemia in patients of the European Sleep Apnea Database (ESADA) cohort. Methods The cross-sectional analysis included 11 892 patients (age 51.9 +/- 12.5 years, 70% male, body mass index (BMI) 31.3 +/- 6.6 kg/m(2), mean oxygen desaturation index (ODI) 23.7 +/- 25.5 events/h) investigated for OSA. The independent odds ratio (OR) for hyperlipidaemia in relation to measures of OSA (ODI, apnoea-hypopnoea index, mean and lowest oxygen saturation) was determined by means of general linear model analysis with adjustment for important confounders such as age, BMI, comorbidities and study site. Results Hyperlipidaemia prevalence increased from 15.1% in subjects without OSA to 26.1% in those with severe OSA, P < 0.001. Corresponding numbers in patients with diabetes were 8.5% and 41.5%, P < 0.001. Compared with ODI quartile I, patients in ODI quartiles II-IV had an adjusted OR (95% CI) of 1.33 (1.15-1.55), 1.37 (1.17-1.61) and 1.33 (1.12-1.58) (P < 0.001), respectively, for hyperlipidaemia. Obesity was defined as a significant risk factor for hyperlipidaemia. Subgroups of OSA patients with cardio-metabolic comorbidities demonstrated higher prevalence of HL. In addition, differences in hyperlipidaemia prevalence were reported in European geographical regions with the highest prevalence in Central Europe. Conclusion Obstructive sleep apnoea, in particular intermittent hypoxia, was independently associated with the prevalence of hyperlipidaemia diagnosis.
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| 4. |
- Bonsignore, M. R., et al.
(författare)
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Clinical presentation of patients with suspected obstructive sleep apnea and self-reported physician-diagnosed asthma in the ESADA cohort
- 2018
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 27:6
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Tidskriftsartikel (refereegranskat)abstract
- Obstructive sleep apnea (OSA) and asthma are often associated and several studies suggest a bidirectional relationship between asthma and OSA. This study analyzed the characteristics of patients with suspected OSA from the European Sleep Apnea Database according to presence/absence of physician-diagnosed asthma. Cross-sectional data in 16,236 patients (29.1% female) referred for suspected OSA were analyzed according to occurrence of physician-diagnosed asthma for anthropometrics, OSA severity and sleepiness. Sleep structure was assessed in patients studied by polysomnography (i.e. 48% of the sample). The prevalence of physician-diagnosed asthma in the entire cohort was 4.8% (7.9% in women, 3.7% in men, p < 0.0001), and decreased from subjects without OSA to patients with mild-moderate and severe OSA (p = 0.02). Obesity was highly prevalent in asthmatic women, whereas BMI distribution was similar in men with and without physician-diagnosed asthma. Distribution of OSA severity was similar in patients with and without physician-diagnosed asthma, and unaffected by treatment for asthma or gastroesophageal reflux. Asthma was associated with poor sleep quality and sleepiness. Physician-diagnosed asthma was less common in a sleep clinic population than expected from the results of studies in the general population. Obesity appears as the major factor raising suspicion of OSA in asthmatic women, whereas complaints of poor sleep quality were the likely reason for referral in asthmatic men.
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| 5. |
- Bonsignore, M. R., et al.
(författare)
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Excessive Daytime Sleepiness in Obstructive Sleep Apnea Patients Treated With Continuous Positive Airway Pressure: Data From the European Sleep Apnea Database
- 2021
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Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- follow-up visit after 4 months to 2 years. The change in ESS (n = 2,190) was weakly correlated with CPAP use (R2 = 0.023, p 0.0001). Logistic regression showed that an ESS score 10 at the first follow-up visit was associated directly with ESS at baseline and inversely with duration of follow-up, and CPAP use (R2 of the model: 0.417). EDS showed heterogeneity in different European countries both at baseline and at the first follow-up visit, suggesting modulation by cultural and lifestyle factors. In conclusion, residual EDS in CPAP-treated OSA occurred in approximately one in four patients at follow-up; its prevalence was highest (40%) in the first 3 months of treatment and subsequently decreased. The finding of residual EDS in a significant percentage of optimally treated OSA patients suggests that wake-promoting agents may be useful, but their indication should be evaluated after at least 3 months of treatment.
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| 6. |
- Bouloukaki, I., et al.
(författare)
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Mild obstructive sleep apnea increases hypertension risk, challenging traditional severity classification
- 2020
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Ingår i: Journal of Clinical Sleep Medicine. - : American Academy of Sleep Medicine (AASM). - 1550-9389 .- 1550-9397. ; 16:6, s. 889-898
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Tidskriftsartikel (refereegranskat)abstract
- Study Objectives: The association of mild obstructive sleep apnea (OSA) with important clinical outcomes remains unclear. We aimed to investigate the association between mild OSA and systemic arterial hypertension (SAH) in the European Sleep Apnea Database cohort. Methods: In a multicenter sample of 4,732 participants, we analyzed the risk of mild OSA (subclassified into 2 groups: mild(AHI) (5-<)(11)(/h) (apnea-hypopnea index [AHI], 5 to <11 events/h) and mild(AHI) (1)(1-<15/h) (AHI, >= 11 to <15 events/h) compared with nonapneic snorers for prevalent SAH after adjustment for relevant confounding factors including sex, age, smoking, obesity, daytime sleepiness, dyslipidemia, chronic obstructive pulmonary disease, type 2 diabetes, and sleep test methodology (polygraphy or polysomnography). Results: SAH prevalence was higher in the mild(AHI) (11-<15/h) OSA group compared with the mild(AHI 5-<11/h) group and nonapneic snorers (52% vs 45% vs 30%; P < .001). Corresponding adjusted odds ratios for SAH were 1.789 (mild(AHI) (11-<15/h); 95% confidence interval [CI], 1.49-2.15) and 1.558 (mild 1.34-1.82), respectively (P < .001). In sensitivity analysis, mild(AHI) (11-<15/h) OSA remained a significant predictor for SAH both in the polygraphy (odds ratio, 1.779; 95% CI, 1.403-2.256; P < .001) and polysomnography groups (odds ratio, 1.424; 95% CI, 1.047-1.939; P = .025). Conclusions: Our data suggest a dose-response relationship between mild OSA and SAH risk, starting from 5 events/h in polygraphy recordings and continuing with a further risk increase in the 11- to <150-events/h range. These findings potentially introduce a challenge to traditional thresholds of OSA severity and may help to stratify participants with OSA according to cardiovascular risk.
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| 7. |
- Chirapatpimol, K, et al.
(författare)
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Precision Measurement of the p(e,e′p)π0 Reaction at Threshold
- 2015
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Ingår i: Physical Review Letters. - 1079-7114. ; 114:19
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Tidskriftsartikel (refereegranskat)abstract
- New results are reported from a measurement of π^{0} electroproduction near threshold using the p(e,e^{'}p)π^{0} reaction. The experiment was designed to determine precisely the energy dependence of s- and p-wave electromagnetic multipoles as a stringent test of the predictions of chiral perturbation theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the ϕ_{π}^{*} and θ_{π}^{*} angles in the pπ^{0} center of mass was obtained for invariant energies above threshold from 0.5 up to 15 MeV. The 4-momentum transfer Q^{2} coverage ranges from 0.05 to 0.155 (GeV/c)^{2} in fine steps. A simple phenomenological analysis of our data shows strong disagreement with p-wave predictions from ChPT for Q^{2}>0.07 (GeV/c)^{2}, while the s-wave predictions are in reasonable agreement.
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| 8. |
- Gunduz, C., et al.
(författare)
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Long-term positive airway pressure therapy is associated with reduced total cholesterol levels in patients with obstructive sleep apnea: data from the European Sleep Apnea Database (ESADA)
- 2020
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Ingår i: Sleep Medicine. - : Elsevier BV. - 1389-9457. ; 75, s. 201-209
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Tidskriftsartikel (refereegranskat)abstract
- Background and aim: Obstructive sleep apnea (OSA) is an independent risk factor for dyslipidemia. The current study examined the effects of positive airway pressure (PAP) treatment on lipid status in the European Sleep Apnea Database (ESADA). Methods: The prospective cohort study enrolled 1564 OSA subjects (74% male, mean age 54 ± 11y, body mass index (BMI) 32.7 ± 6.6 kg/m2 and apnea-hypopnea index (AHI) 40.3 ± 24.4 n/h) undergoing PAP therapy for at least three months (mean 377.6 ± 419.5 days). Baseline and follow-up total cholesterol (TC) from nine centers were analyzed. Repeated measures and logistic regression tests (adjusted for age, sex, weight changes, lipid lowering medication, PAP compliance, and treatment duration) were used to compare changes in TC concentration. Incident risk for a coronary heart disease event (CHD) was used to compute a Framingham CHD risk score (estimated from age, BMI, blood pressure, and TC). Results: Adjusted means of TC decreased from 194.2 mg/dl to 189.3 mg/dl during follow-up (p = 0.019). A clinically significant (10%) reduction of TC at PAP follow-up was observed in 422 patients (27%). Duration of PAP therapy was identified as independent predictor for TC reduction, which implies an approximately 10% risk reduction for incident CHD events (from 26.7% to 24.1% in men and from 11.2% to 10.1% in women, p < 0.001 respectively). Conclusion: This observational study demonstrates a reduction of TC after long-term PAP treatment. The close association between TC concentration and cardiovascular (CV) mortality suggests that identification and treatment of OSA may have a beneficial effect on overall CV risk due to this mechanism. This possibility needs to be evaluated in prospective randomized studies. © 2020 Elsevier B.V.
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| 9. |
- Lombardi, C., et al.
(författare)
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Periodic limb movements during sleep and blood pressure changes in sleep apnoea: Data from the European Sleep Apnoea Database
- 2020
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Ingår i: Respirology. - : Wiley. - 1323-7799 .- 1440-1843. ; 25:8, s. 872-879
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Tidskriftsartikel (refereegranskat)abstract
- Background and objective OSA and PLMS are known to induce acute BP swings during sleep. Our current study aimed to address the independent effect of PLMS on BP in an unselected OSA patient cohort. Methods This cross‐sectional analysis included 1487 patients (1110 males, no previous hypertension diagnosis or treatment, mean age: 52.5years, mean BMI: 30.5kg/m2) with significant OSA (defined as AHI≥10) recruited from the European Sleep Apnoea Cohort. Patients underwent overnight PSG. Patients were stratified into two groups: patients with significant PLMS (PLMSI>25 events/hour of sleep) and patients without significant PLMS (PLMSI<25 events/hour of sleep). SBP, DBP and PP were the variables of interest. For each of these, a multivariate regression linear model was fitted to evaluate the relationship between PLMS and outcome adjusting for sociodemographic and clinical covariates (gender, age, BMI, AHI, ESS, diabetes, smoking and sleep efficiency). Results The univariate analysis of SBP showed an increment of BP equal to 4.70mm Hg (P<0.001) in patients with significant PLMS compared to patients without significant PLMS. This increment remained significant after implementing a multivariate regression model (2.64mm Hg, P = 0.044). No significant increment of BP was observed for DBP and PP. Conclusion PLMS is associated with a rise in SBP regardless of AHI, independent of clinical and sociodemographic confounders. A PLMS phenotype may carry an increased risk for cardiovascular disease in OSA patients.
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| 10. |
- Marrone, O., et al.
(författare)
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Fixed But Not Autoadjusting Positive Airway Pressure Attenuates the Time-dependent Decline in Glomerular Filtration Rate in Patients With OSA
- 2018
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Ingår i: Chest. - : Elsevier BV. - 0012-3692. ; 154:2, s. 326-334
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The impact of treating OSA on renal function decline is controversial. Previous studies usually included small samples and did not consider specific effects of different CPAP modalities. The aim of this study was to evaluate the respective influence of fixed and autoadjusting CPAP modes on estimated glomerular filtration rate (eGFR) in a large sample of patients derived from the prospective European Sleep Apnea Database cohort. METHODS: In patients of the European Sleep Apnea Database, eGFR prior to and after follow-up was calculated by using the Chronic Kidney Disease-Epidemiology Collaboration equation. Three study groups were investigated: untreated patients (n = 144), patients receiving fixed CPAP (fCPAP) (n = 1,178), and patients on autoadjusting CPAP (APAP) (n = 485). RESULTS: In the whole sample, eGFR decreased over time. The rate of eGFR decline was significantly higher in the subgroup with eGFR above median (91.42 mL/min/1.73 m(2)) at baseline (P < .0001 for effect of baseline eGFR). This decline was attenuated or absent (P < .0001 for effect of treatment) in the subgroup of patients with OSA treated by using fCPAP. A follow-up duration exceeding the median (541 days) was associated with eGFR decline in the untreated and APAP groups but not in the fCPAP group (P < .0001 by two-way ANOVA for interaction between treatment and follow-up length). In multiple regression analysis, eGFR decline was accentuated by advanced age, female sex, cardiac failure, higher baseline eGFR, and longer follow-up duration, whereas there was a protective effect of fCPAP. CONCLUSIONS: fCPAP but not APAP may prevent eGFR decline in OSA.
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| 11. |
- Paradela, C., et al.
(författare)
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High accuracy 235U(n,f) data in the resonance energy region
- 2016
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X.
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Konferensbidrag (refereegranskat)abstract
- The U-235 neutron-induced cross section is widely used as reference cross section for measuring other fission cross sections, but in the resonance region it is not considered as an IAEA standard because of the scarce experimental data covering the full region. In this work, we deal with a new analysis of the experimental data obtained with a detection setup based on parallel plate ionization chambers (PPACs) at the CERN n_TOF facility in the range from 1 eV to 10 keV. The relative cross section has been normalised to the IAEA value in the region between 7.8 and 11 eV, which is claimed as well-known. Comparison with the ENDF/B-VII evaluation and the IAEA reference file from 100 eV to 10 keV are provided.
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| 12. |
- Tasbakan, M. S., et al.
(författare)
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Positive airway pressure (PAP) treatment reduces glycated hemoglobin (HbA1c) levels in obstructive sleep apnea patients with concomitant weight loss: Longitudinal data from the ESADA
- 2021
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 30:5
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Tidskriftsartikel (refereegranskat)abstract
- Patients with obstructive sleep apnea (OSA) are at increased risk of developing metabolic disease such as diabetes. The effects of positive airway pressure on glycemic control are contradictory. We therefore evaluated the change in glycated hemoglobin (HbA1c) in a large cohort of OSA patients after long-term treatment with positive airway pressure. HbA1c levels were assessed in a subsample of the European Sleep Apnea Database [n=1608] at baseline and at long-term follow up with positive airway pressure therapy (mean 378.9±423.0 days). In a regression analysis, treatment response was controlled for important confounders. Overall, HbA1c decreased from 5.98±1.01% to 5.93±0.98% (p=0.001). Patient subgroups with a more pronounced HbA1c response included patients with diabetes (−0.15±1.02, p=0.019), those with severe OSA baseline (−0.10±0.68, p=0.005), those with morbid obesity (−0.20±0.81, p<0.001). The strongest HbA1c reduction was observed in patients with a concomitant weight reduction >5 kilos (−0.38±0.99, p<0.001). In robust regression analysis, severe OSA (p=0.038) and morbid obesity (p=0.005) at baseline, and weight reduction >5 kilos (p<0.001) during follow up were independently associated with a reduction of HbA1c following PAP treatment. In contrast, PAP treatment alone without weight reduction was not associated with significant Hb1Ac reduction. In conclusion, positive airway pressure therapy is associated with HbA1c reduction in patients with severe OSA, in morbidly obese patients. and most obviously in those with significant weight lost during the follow-up. Our study underlines the importance to combine positive airway pressure use with adjustments in lifestyle to substantially modify metabolic complications in OSA. © 2021 European Sleep Research Society
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| 13. |
- Akiyama, Kazunori, et al.
(författare)
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First M87 Event Horizon Telescope Results. IX. Detection of Near-horizon Circular Polarization
- 2023
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 957:2
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Tidskriftsartikel (refereegranskat)abstract
- Event Horizon Telescope (EHT) observations have revealed a bright ring of emission around the supermassive black hole at the center of the M87 galaxy. EHT images in linear polarization have further identified a coherent spiral pattern around the black hole, produced from ordered magnetic fields threading the emitting plasma. Here we present the first analysis of circular polarization using EHT data, acquired in 2017, which can potentially provide additional insights into the magnetic fields and plasma composition near the black hole. Interferometric closure quantities provide convincing evidence for the presence of circularly polarized emission on event-horizon scales. We produce images of the circular polarization using both traditional and newly developed methods. All methods find a moderate level of resolved circular polarization across the image (〈|v|〉 < 3.7%), consistent with the low image-integrated circular polarization fraction measured by the Atacama Large Millimeter/submillimeter Array (|vint| < 1%). Despite this broad agreement, the methods show substantial variation in the morphology of the circularly polarized emission, indicating that our conclusions are strongly dependent on the imaging assumptions because of the limited baseline coverage, uncertain telescope gain calibration, and weakly polarized signal. We include this upper limit in an updated comparison to general relativistic magnetohydrodynamic simulation models. This analysis reinforces the previously reported preference for magnetically arrested accretion flow models. We find that most simulations naturally produce a low level of circular polarization consistent with our upper limit and that Faraday conversion is likely the dominant production mechanism for circular polarization at 230 GHz in M87*
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| 14. |
- Akiyama, Kazunori, et al.
(författare)
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First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
- 2022
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we quantify the temporal variability and image morphology of the horizon-scale emission from Sgr A*, as observed by the EHT in 2017 April at a wavelength of 1.3 mm. We find that the Sgr A* data exhibit variability that exceeds what can be explained by the uncertainties in the data or by the effects of interstellar scattering. The magnitude of this variability can be a substantial fraction of the correlated flux density, reaching similar to 100% on some baselines. Through an exploration of simple geometric source models, we demonstrate that ring-like morphologies provide better fits to the Sgr A* data than do other morphologies with comparable complexity. We develop two strategies for fitting static geometric ring models to the time-variable Sgr A* data; one strategy fits models to short segments of data over which the source is static and averages these independent fits, while the other fits models to the full data set using a parametric model for the structural variability power spectrum around the average source structure. Both geometric modeling and image-domain feature extraction techniques determine the ring diameter to be 51.8 +/- 2.3 mu as (68% credible intervals), with the ring thickness constrained to have an FWHM between similar to 30% and 50% of the ring diameter. To bring the diameter measurements to a common physical scale, we calibrate them using synthetic data generated from GRMHD simulations. This calibration constrains the angular size of the gravitational radius to be 4.8(-0.7)(+1.4) mu as, which we combine with an independent distance measurement from maser parallaxes to determine the mass of Sgr A* to be 4.0(-0.6)(+1.1) x 10(6) M-circle dot.
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| 15. |
- Akiyama, Kazunori, et al.
(författare)
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First Sagittarius A∗ Event Horizon Telescope Results. VII. Polarization of the Ring
- 2024
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 964:2
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Tidskriftsartikel (refereegranskat)abstract
- The Event Horizon Telescope observed the horizon-scale synchrotron emission region around the Galactic center supermassive black hole, Sagittarius A∗ (Sgr A∗), in 2017. These observations revealed a bright, thick ring morphology with a diameter of 51.8 ± 2.3 μas and modest azimuthal brightness asymmetry, consistent with the expected appearance of a black hole with mass M≈ 4 × 106 M⊙. From these observations, we present the first resolved linear and circular polarimetric images of Sgr A∗. The linear polarization images demonstrate that the emission ring is highly polarized, exhibiting a prominent spiral electric vector polarization angle pattern with a peak fractional polarization of ∼40% in the western portion of the ring. The circular polarization images feature a modestly (∼5%°-10%) polarized dipole structure along the emission ring, with negative circular polarization in the western region and positive circular polarization in the eastern region, although our methods exhibit stronger disagreement than for linear polarization. We analyze the data using multiple independent imaging and modeling methods, each of which is validated using a standardized suite of synthetic data sets. While the detailed spatial distribution of the linear polarization along the ring remains uncertain owing to the intrinsic variability of the source, the spiraling polarization structure is robust to methodological choices. The degree and orientation of the linear polarization provide stringent constraints for the black hole and its surrounding magnetic fields, which we discuss in an accompanying publication.
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| 16. |
- Akiyama, Kazunori, et al.
(författare)
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First Sagittarius A∗ Event Horizon Telescope Results. VIII. Physical Interpretation of the Polarized Ring
- 2024
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 964:2
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Tidskriftsartikel (refereegranskat)abstract
- In a companion paper, we present the first spatially resolved polarized image of Sagittarius A∗ on event horizon scales, captured using the Event Horizon Telescope, a global very long baseline interferometric array operating at a wavelength of 1.3 mm. Here we interpret this image using both simple analytic models and numerical general relativistic magnetohydrodynamic (GRMHD) simulations. The large spatially resolved linear polarization fraction (24%-28%, peaking at ∼40%) is the most stringent constraint on parameter space, disfavoring models that are too Faraday depolarized. Similar to our studies of M87∗, polarimetric constraints reinforce a preference for GRMHD models with dynamically important magnetic fields. Although the spiral morphology of the polarization pattern is known to constrain the spin and inclination angle, the time-variable rotation measure (RM) of Sgr A∗ (equivalent to ≈ 46° ± 12° rotation at 228 GHz) limits its present utility as a constraint. If we attribute the RM to internal Faraday rotation, then the motion of accreting material is inferred to be counterclockwise, contrary to inferences based on historical polarized flares, and no model satisfies all polarimetric and total intensity constraints. On the other hand, if we attribute the mean RM to an external Faraday screen, then the motion of accreting material is inferred to be clockwise, and one model passes all applied total intensity and polarimetric constraints: a model with strong magnetic fields, a spin parameter of 0.94, and an inclination of 150°. We discuss how future 345 GHz and dynamical imaging will mitigate our present uncertainties and provide additional constraints on the black hole and its accretion flow.
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| 17. |
- Akiyama, Kazunori, et al.
(författare)
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The persistent shadow of the supermassive black hole of M 87: I. Observations, calibration, imaging, and analysis*
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 681
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Tidskriftsartikel (refereegranskat)abstract
- In April 2019, the Event Horizon Telescope (EHT) Collaboration reported the first-ever event-horizon-scale images of a black hole, resolving the central compact radio source in the giant elliptical galaxy M 87. These images reveal a ring with a southerly brightness distribution and a diameter of ∼42 μas, consistent with the predicted size and shape of a shadow produced by the gravitationally lensed emission around a supermassive black hole. These results were obtained as part of the April 2017 EHT observation campaign, using a global very long baseline interferometric radio array operating at a wavelength of 1.3 mm. Here, we present results based on the second EHT observing campaign, taking place in April 2018 with an improved array, wider frequency coverage, and increased bandwidth. In particular, the additional baselines provided by the Greenland telescope improved the coverage of the array. Multiyear EHT observations provide independent snapshots of the horizon-scale emission, allowing us to confirm the persistence, size, and shape of the black hole shadow, and constrain the intrinsic structural variability of the accretion flow. We have confirmed the presence of an asymmetric ring structure, brighter in the southwest, with a median diameter of 43.3-3.1+1.5 μas. The diameter of the 2018 ring is remarkably consistent with the diameter obtained from the previous 2017 observations. On the other hand, the position angle of the brightness asymmetry in 2018 is shifted by about 30 relative to 2017. The perennial persistence of the ring and its diameter robustly support the interpretation that the ring is formed by lensed emission surrounding a Kerr black hole with a mass ∼6.5× 109M. The significant change in the ring brightness asymmetry implies a spin axis that is more consistent with the position angle of the large-scale jet.
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| 18. |
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| 19. |
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| 20. |
- Diakaki, M., et al.
(författare)
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Towards the high-accuracy determination of the 238U fission cross section at the threshold region at CERN -€“ n_TOF
- 2016
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X.
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Konferensbidrag (refereegranskat)abstract
- The U-238 fission cross section is an international standard beyond 2 MeV where the fission plateau starts. However, due to its importance in fission reactors, this cross-section should be very accurately known also in the threshold region below 2 MeV. The U-238 fission cross section has been measured relative to the U-235 fission cross section at CERN - n_TOF with different detection systems. These datasets have been collected and suitably combined to increase the counting statistics in the threshold region from about 300 keV up to 3 MeV. The results are compared with other experimental data, evaluated libraries, and the IAEA standards.
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| 21. |
- Elvstam, O., et al.
(författare)
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Associations between HIV viremia during antiretroviral therapy and cardiovascular disease
- 2022
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Ingår i: Aids. - : Ovid Technologies (Wolters Kluwer Health). - 0269-9370 .- 1473-5571. ; 36:13, s. 1829-1834
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To investigate the association between HIV viremia exposure during antiretroviral therapy (ART) and cardiovascular disease (CVD) risk. Design: Nationwide observational cohort. Methods: Participants (age >15 years) from the Swedish nationwide InfCareHIV register initiating ART 1996-2017 were categorized in a time-updated manner into four viremia categories, starting from 12 months after ART initiation: suppression (<50 copies/ml), low-level viremia (50-199 copies/ml and 200-999 copies/ml, respectively), and high-level viremia (>= 1000 copies/ml). In addition, cumulative viremia was estimated as the area under the log viral load (VL) curve. Proportional subhazard models adjusted for sex, age, pre-ART CD4 and VL, injection drug use, and country of birth were used to analyze the association between viremia exposure and CVD risk (ischemic heart disease, stroke, and heart failure; data obtained by linkage to national registers), accounting for the competing risk of non-CVD death. Results: In all, 337 cases of CVD were observed during 44 937 person-years of follow-up (n = 6562). Higher viremia exposure was associated with CVD, both when parameterized as cumulative viremia (adjusted subhazard ratio [aSHR] per 1 log(10) copy x year/ml, 1.03; 95% confidence interval [CI], 1.01-1.05) and as viremia category (aSHR for high-level viremia versus suppression, 1.45; 95% CI, 1.03-2.05). We observed no association between CVD and low-level viremia compared with those with suppression. Conclusions: Higher exposure to HIV viremia was linked to CVD in ART recipients, whereas no increased risk was detected for people with low-level viremia compared with viral suppression. Causal inference is limited by the observational nature of this study.
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| 22. |
- Fietze, I, et al.
(författare)
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Management of obstructive sleep apnea in Europe
- 2011
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Ingår i: Sleep Medicine. - : Elsevier. - 1389-9457 .- 1878-5506. ; 12:2, s. 190-197
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: In Europe, the services provided for the investigation and management of obstructive sleep apnoea (OSA) varies from country to country. The aim of this questionnaire-based study was to investigate the current status of diagnostic pathways and therapeutic approaches applied in the treatment of OSA in Europe, qualification requirements of physicians involved in diagnosis and treatment of OSA, and reimbursement of these services. Methods: Two questionnaires were sent to 39 physicians in 22 countries in Europe. In order to standardize the responses, the questionnaire was accompanied by an example. Results: Sleep centers from 21 countries (38 physicians) participated. A broad consistency among countries with respect to the following was found: pathways included referral to sleep physicians/sleep laboratories, necessity for objective diagnosis (primarily by polysomnography), use of polygraphic methods, analysis of polysomnography (PSG), indications for positive airway pressure (PAP) therapy, application of standard continuous PAP (CPAP) therapy (100% with an CPAP/APAP ratio of 2.24:1), and the need (90.5%) and management of follow-up. Differences were apparent in reimbursement of the diagnostic procedures and follow-up, in the procedures for PAP titration from home APAP titration with portable sleep apnea monitoring (38.1%) up to hospital monitoring with PSG and APAP (85.7%), and in the qualification requirements of sleep physicians. Conclusions: Management of OSA in different European countries is similar except for reimbursement rules, qualification of sleep specialists and procedures for titration of the CPAP treatment. A European network (such as the one accomplished by the European Cooperation in Science and Technology [COST] B26 Action) could be helpful for implementing these findings into health-service research in order to standardize management in a cost effective perspective.
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| 23. |
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| 24. |
- Narayan, Ramesh, et al.
(författare)
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The Polarized Image of a Synchrotron-emitting Ring of Gas Orbiting a Black Hole
- 2021
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 912:1
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Tidskriftsartikel (refereegranskat)abstract
- Synchrotron radiation from hot gas near a black hole results in a polarized image. The image polarization is determined by effects including the orientation of the magnetic field in the emitting region, relativistic motion of the gas, strong gravitational lensing by the black hole, and parallel transport in the curved spacetime. We explore these effects using a simple model of an axisymmetric, equatorial accretion disk around a Schwarzschild black hole. By using an approximate expression for the null geodesics derived by Beloborodov and conservation of the Walker-Penrose constant, we provide analytic estimates for the image polarization. We test this model using currently favored general relativistic magnetohydrodynamic simulations of M87*, using ring parameters given by the simulations. For a subset of these with modest Faraday effects, we show that the ring model broadly reproduces the polarimetric image morphology. Our model also predicts the polarization evolution for compact flaring regions, such as those observed from Sgr A* with GRAVITY. With suitably chosen parameters, our simple model can reproduce the EVPA pattern and relative polarized intensity in Event Horizon Telescope images of M87*. Under the physically motivated assumption that the magnetic field trails the fluid velocity, this comparison is consistent with the clockwise rotation inferred from total intensity images.
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| 25. |
- Paraschos, Georgios Filippos, et al.
(författare)
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Ordered magnetic fields around the 3C 84 central black hole
- 2024
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Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 682
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Tidskriftsartikel (refereegranskat)abstract
- Context . 3C 84 is a nearby radio source with a complex total intensity structure, showing linear polarisation and spectral patterns. A detailed investigation of the central engine region necessitates the use of very-long-baseline interferometry (VLBI) above the hitherto available maximum frequency of 86 GHz. Aims. Using ultrahigh resolution VLBI observations at the currently highest available frequency of 228 GHz, we aim to perform a direct detection of compact structures and understand the physical conditions in the compact region of 3C 84. Methods . We used Event Horizon Telescope (EHT) 228 GHz observations and, given the limited (u, v)-coverage, applied geometric model fitting to the data. Furthermore, we employed quasi-simultaneously observed, ancillary multi-frequency VLBI data for the source in order to carry out a comprehensive analysis of the core structure. Results . We report the detection of a highly ordered, strong magnetic field around the central, supermassive black hole of 3C 84. The brightness temperature analysis suggests that the system is in equipartition. We also determined a turnover frequency of νm = (113 ± 4) GHz, a corresponding synchrotron self-absorbed magnetic field of BSSA = (2.9 ± 1.6) G, and an equipartition magnetic field of Beq = (5.2 ± 0.6) G. Three components are resolved with the highest fractional polarisation detected for this object (mnet = (17.0 ± 3.9)%). The positions of the components are compatible with those seen in low-frequency VLBI observations since 2017-2018. We report a steeply negative slope of the spectrum at 228 GHz. We used these findings to test existing models of jet formation, propagation, and Faraday rotation in 3C 84. Conclusions . The findings of our investigation into different flow geometries and black hole spins support an advection-dominated accretion flow in a magnetically arrested state around a rapidly rotating supermassive black hole as a model of the jet-launching system in the core of 3C 84. However, systematic uncertainties due to the limited (u, v)-coverage, however, cannot be ignored. Our upcoming work using new EHT data, which offer full imaging capabilities, will shed more light on the compact region of 3C 84.
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| 26. |
- Roelofs, F., et al.
(författare)
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Polarimetric Geometric Modeling for mm-VLBI Observations of Black Holes
- 2023
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Ingår i: Astrophysical Journal Letters. - 2041-8213 .- 2041-8205. ; 957:2
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Tidskriftsartikel (refereegranskat)abstract
- The Event Horizon Telescope (EHT) is a millimeter very long baseline interferometry (VLBI) array that has imaged the apparent shadows of the supermassive black holes M87* and Sagittarius A*. Polarimetric data from these observations contain a wealth of information on the black hole and accretion flow properties. In this work, we develop polarimetric geometric modeling methods for mm-VLBI data, focusing on approaches that fit data products with differing degrees of invariance to broad classes of calibration errors. We establish a fitting procedure using a polarimetric “m-ring” model to approximate the image structure near a black hole. By fitting this model to synthetic EHT data from general relativistic magnetohydrodynamic models, we show that the linear and circular polarization structure can be successfully approximated with relatively few model parameters. We then fit this model to EHT observations of M87* taken in 2017. In total intensity and linear polarization, the m-ring fits are consistent with previous results from imaging methods. In circular polarization, the m-ring fits indicate the presence of event-horizon-scale circular polarization structure, with a persistent dipolar asymmetry and orientation across several days. The same structure was recovered independently of observing band, used data products, and model assumptions. Despite this broad agreement, imaging methods do not produce similarly consistent results. Our circular polarization results, which imposed additional assumptions on the source structure, should thus be interpreted with some caution. Polarimetric geometric modeling provides a useful and powerful method to constrain the properties of horizon-scale polarized emission, particularly for sparse arrays like the EHT.
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| 27. |
- Roy, Alan, et al.
(författare)
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VLBI at APEX: First Fringes
- 2012
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Ingår i: Proceedings of Science. - 1824-8039. ; 2012-October
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Konferensbidrag (refereegranskat)
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| 28. |
- Svedmyr, Sven, 1976, et al.
(författare)
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Superior hypertension control with betablockade in the European Sleep Apnea Database
- 2021
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Ingår i: Journal of Hypertension. - : Ovid Technologies (Wolters Kluwer Health). - 0263-6352 .- 1473-5598. ; 39:2, s. 292-301
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Arterial hypertension is highly prevalent and difficult to control in patients with obstructive sleep apnea (OSA). High sympathoadrenergic activity is a hallmark physiological phenomenon in OSA. We hypothesized that an antihypertensive drug with inhibitory properties on this activity, such as beta blockers (BBs), may be particularly efficacious in OSA patients. Methods: Hypertensive OSA patients receiving blood pressure-lowing treatment in the European Sleep A pnea Database (ESADA) (n =5818, 69% men, age 58 +/- 11 years, body mass index 33 +/- 7 kg/m(2), apnea hypopnea index 34 +/- 26 events/h) were analyzed. Reported medications [BB, diuretic, renin-angiotensin blocker (RAB), calcium channel blocker (CCB), and centrally acting antihypertensive (CAH)] were classified according to ATC code. Office blood pressure was compared in patients with monotherapy or combination therapy controlling for confounders. Results: Poorly controlled SBP according to the ESC/ESH guidelines was found in 66% of patients. Patients receiving monotherapy with RAB, CCB or CAH had 2.2 (95% CI 1.4-3.0), 3.0 (1.9-4.1) and 3.0 (1.7-4.7) mmHg higher SBP compared with those on BB (adjusted model, P=0.007, 0.008 and 0.017, respectively). In those with a combination of two antihypertensive drugs, SBP was 5.5 (4.0-7.1), 5.1 (3.7-6.6), 4.3 (2.5-6.1) and 3.1 (1.6-4.6) mmHg higher in those on CCB/RAB, BB/RAB, BB/CCB or diuretic/RAB compared with those on BB/diuretic (adjusted model, P< 0.001, <0.001, 0.018 and 0.036, respectively). Conclusion: Poorly controlled blood pressure was common in OSA patients with antihypertensive medication. Treatment with BB alone or BB in combination with a diuretic was associated with the lowest systolic pressure in this large clinical cohort.
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| 29. |
- Torne, Pablo, et al.
(författare)
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A Search for Pulsars around Sgr A* in the First Event Horizon Telescope Data Set
- 2023
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 959:1
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Tidskriftsartikel (refereegranskat)abstract
- In 2017 the Event Horizon Telescope (EHT) observed the supermassive black hole at the center of the Milky Way, Sagittarius A* (Sgr A*), at a frequency of 228.1 GHz (lambda = 1.3 mm). The fundamental physics tests that even a single pulsar orbiting Sgr A* would enable motivate searching for pulsars in EHT data sets. The high observing frequency means that pulsars-which typically exhibit steep emission spectra-are expected to be very faint. However, it also negates pulse scattering, an effect that could hinder pulsar detections in the Galactic center. Additionally, magnetars or a secondary inverse Compton emission could be stronger at millimeter wavelengths than at lower frequencies. We present a search for pulsars close to Sgr A* using the data from the three most sensitive stations in the EHT 2017 campaign: the Atacama Large Millimeter/submillimeter Array, the Large Millimeter Telescope, and the IRAM 30 m Telescope. We apply three detection methods based on Fourier-domain analysis, the fast folding algorithm, and single-pulse searches targeting both pulsars and burst-like transient emission. We use the simultaneity of the observations to confirm potential candidates. No new pulsars or significant bursts were found. Being the first pulsar search ever carried out at such high radio frequencies, we detail our analysis methods and give a detailed estimation of the sensitivity of the search. We conclude that the EHT 2017 observations are only sensitive to a small fraction (less than or similar to 2.2%) of the pulsars that may exist close to Sgr A*, motivating further searches for fainter pulsars in the region.
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| 30. |
- Wagner, J., et al.
(författare)
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First 230? : GHz VLBI fringes on 3C 279 using the APEX Telescope (Research Note)
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 581
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Tidskriftsartikel (refereegranskat)abstract
- Aims. We report about a 230? GHz very long baseline interferometry (VLBI) fringe finder observation of blazar 3C 279 with the APEX telescope in Chile, the phased submillimeter array (SMA), and the SMT of the Arizona Radio Observatory (ARO). Methods. We installed VLBI equipment and measured the APEX station position to 1? cm accuracy (1σ). We then observed 3C 279 on 2012 May 7 in a 5? h 230? GHz VLBI track with baseline lengths of 2800? Mλ to 7200? Mλ and a finest fringe spacing of 28.6? μas. Results. Fringes were detected on all baselines with signal-to-noise ratios of 12 to 55 in 420? s. The correlated flux density on the longest baseline was ∼0.3? Jy beam-1, out of a total flux density of 19.8? Jy. Visibility data suggest an emission region ≤ 38? μas in size, and at least two components, possibly polarized. We find a lower limit of the brightness temperature of the inner jet region of about 1010? K. Lastly, we find an upper limit of 20% on the linear polarization fraction at a fringe spacing of ∼ 38? μas. Conclusions. With APEX the angular resolution of 230? GHz VLBI improves to 28.6? μas. This allows one to resolve the last-photon ring around the Galactic Center black hole event horizon, expected to be 40? μas in diameter, and probe radio jet launching at unprecedented resolution, down to a few gravitational radii in galaxies like M 87. To probe the structure in the inner parsecs of 3C 279 in detail, follow-up observations with APEX and five other mm-VLBI stations have been conducted (March 2013) and are being analyzed.
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