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- Kim, Jae-Young, et al.
(författare)
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Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution
- 2020
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640
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Tidskriftsartikel (refereegranskat)abstract
- 3C 279 is an archetypal blazar with a prominent radio jet that show broadband flux density variability across the entire electromagnetic spectrum. We use an ultra-high angular resolution technique - global Very Long Baseline Interferometry (VLBI) at 1.3mm (230 GHz) - to resolve the innermost jet of 3C 279 in order to study its fine-scale morphology close to the jet base where highly variable-ray emission is thought to originate, according to various models. The source was observed during four days in April 2017 with the Event Horizon Telescope at 230 GHz, including the phased Atacama Large Millimeter/submillimeter Array, at an angular resolution of ∼20 μas (at a redshift of z = 0:536 this corresponds to ∼0:13 pc ∼ 1700 Schwarzschild radii with a black hole mass MBH = 8 × 108 M⊙). Imaging and model-fitting techniques were applied to the data to parameterize the fine-scale source structure and its variation.We find a multicomponent inner jet morphology with the northernmost component elongated perpendicular to the direction of the jet, as imaged at longer wavelengths. The elongated nuclear structure is consistent on all four observing days and across diffierent imaging methods and model-fitting techniques, and therefore appears robust. Owing to its compactness and brightness, we associate the northern nuclear structure as the VLBI "core". This morphology can be interpreted as either a broad resolved jet base or a spatially bent jet.We also find significant day-to-day variations in the closure phases, which appear most pronounced on the triangles with the longest baselines. Our analysis shows that this variation is related to a systematic change of the source structure. Two inner jet components move non-radially at apparent speeds of ∼15 c and ∼20 c (∼1:3 and ∼1:7 μas day-1, respectively), which more strongly supports the scenario of traveling shocks or instabilities in a bent, possibly rotating jet. The observed apparent speeds are also coincident with the 3C 279 large-scale jet kinematics observed at longer (cm) wavelengths, suggesting no significant jet acceleration between the 1.3mm core and the outer jet. The intrinsic brightness temperature of the jet components are ≤1010 K, a magnitude or more lower than typical values seen at ≥7mm wavelengths. The low brightness temperature and morphological complexity suggest that the core region of 3C 279 becomes optically thin at short (mm) wavelengths.
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- Bernabe, Beatriz Penalver, et al.
(författare)
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Interactions between perceived stress and microbial-host immune components : two demographically and geographically distinct pregnancy cohorts
- 2023
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Ingår i: Translational Psychiatry. - : Springer Nature. - 2158-3188. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Higher stress during pregnancy associates with negative outcomes and elevated inflammation. The gut microbiota, reflecting environment and social interactions, alongside host immune responses have the potential to better understand perceived stress and identify when stress is excessive in pregnancy. Two U.S. cohorts of 84 pregnant individuals, composed of urban women of color and suburban white women, completed the Perceived Stress Scale-10 (PSS-10) and provided fecal and blood samples at two time points. Confirmatory Factor Analysis assessed the robustness of a two-factor PSS-10 model (Emotional Distress/ED and Self-Efficacy/SE). Gut microbiota composition was measured by 16 S rRNA amplicon sequencing and the immune system activity was assessed with a panel of 21 T-cell related cytokines and chemokines. ED levels were higher in the suburban compared to the urban cohort, but levels of SE were similar. ED and SE levels were associated with distinct taxonomical signatures and the gut microbiota data improved the prediction of SE levels compared with models based on socio-demographic characteristics alone. Integration of self-reported symptoms, microbial and immune information revealed a possible mediation effect of Bacteroides uniformis between the immune system (through CXCL11) and SE. The study identified links between distinct taxonomical and immunological signatures with perceived stress. The data are congruent with a model where gut microbiome and immune factors, both impacting and reflecting factors such as close social relationships and dietary fiber, may modulate neural plasticity resulting in increased SE during pregnancy. The predictive value of these peripheral markers merit further study.
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- Santos, Arnoldo, et al.
(författare)
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Acute Respiratory Distress Syndrome deteriorates pulmonary vascular efficiency and increases cardiac energy wasting in a porcine model.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Right ventricle failure worsen outcomes in acute respiratory distress syndrome (ARDS). However, the pathophysiology of right ventricle failure and vascular dysfunction in ARDS is not completely understood. In this study we aim to evaluate the effects of early ARDS on pulmonary vascular efficiency for transmission of flow and pressure in an experimental animal model. Methods: ARDS was induced in 10 pigs (32.5±4.3 kg) combining saline lung-lavages with injurious mechanical ventilation. Pressure and flow sensors were placed at the main pulmonary artery for pulmonary vascular function evaluation, including arterial load parameters, cardiac power and energy transmission ratio.Results: Compared to baseline healthy conditions, ARDS increased pulmonary vascular resistance (199±62 versus 524±154 dyn.s.cm-5, p <0.001), effective arterial elastance (0.65±0.26 versus 1.13±0.36 mmHg/ml, p <0.001) and total hydraulic power (195±60 to 266±87 mW, p =0.015), decreased pulmonary arterial compliance (from 2.34±0.86 to 1.00±0.25 ml/mmHg, p <0.001) and energy transmission ratio (68±15 versus 55±14%, p = 0.014), whereas oscillatory power did not change (17±6 versus 16±6%, p = 0.359).Conclusions: In this experimental ARDS model, an increase in pulmonary arterial load was associated with a higher cardiac power and a decrease in the energy transmission ratio. These results suggest that right ventricle energy consumption is increased and part of this energy is wasted in pulmonary circulation worsening pulmonary vascular efficiency in the early course of ARDS. These findings may help to explain primary mechanisms leading to right ventricle dysfunction in ARDS.
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- Santos, Arnoldo, et al.
(författare)
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Cyclic Changes of Pulmonary Vascular Mechanics During mechanical ventilation in acute respiratory distress syndrome. A porcine experimental model.
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objective: To test the hypothesis that acute respiratory syndrome (ARDS) worsens pulmonary vascular mechanics during the respiratory cycle under mechanical ventilation in an animal model. Design: Experimental study.Setting: Animal research laboratory.Subjects: 6 pigs, 31.7 ± 5.4 kg.Interventions: ARDS was induced by combining saline lung-lavages with injurious mechanical ventilation. Pressure and flow sensors were placed at the main pulmonary artery (PA) and signals were collected simultaneously with airway pressure and flow. Pulmonary vascular mechanics and cardiac function parameters were calculates beat by beat during 2-3 minutes. We designed a novel method to quantify how the calculated variables behave during the whole respiratory cycle, i.e., during expiration and during inspiration. Results are expressed as the mean value during the corresponding phase of the respiratory cycle.Measurements and Main Results: During the whole respiratory cycle and at expiration ARDS decreased SV and arterial compliance while increased mean and pulse PA pressure, effective arterial elastance and Dp/Dtmax when compared to baseline. At baseline and after ARDS, inspiration in positive pressure ventilation caused a decrease in stroke volume (-3±1ml, p<0.001 and -3±1ml, p<0.001), pulmonary mean (-0.5±0.3, p=0.007 and -0.7±0.3mmHg, p=0.002) and pulse pressure (-0.8±0.4, p=0.003 and -1,5±0.7mmHg, p=0.003) and compliance (-0.07±0.04 and -0.04±0.00ml/mmHg, p<0.001) and an increase in resistance (34±13, p=0.001 and 50±32dyn.s.cm-5, p=0.012) and in effective arterial elastance (0.04±0.01, p=0.001 and 0.08±0.04mmHg/ml, p=0.003). ARDS produced a more pronounced inspiratory increase in effective arterial elastance (p=0.041) when compared to baseline. Positive pressure ventilation caused a decrease in Dp/Dtmax at baseline (-15±9mmHg/s, p=0.010) but this was not significant during ARDS (-27±28mmHg/s, p=0.068). Conclusions: We found in this experimental model that MV induced tidal increase in arterial load and that this effect was higher during ARDS. This finding if transferred to patients, might partly explain the high rate of right heart failure clinically in ARDS.
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| 7. |
- Santos, Arnoldo, et al.
(författare)
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Effects on Pulmonary Vascular Mechanics of Two Different Lung-Protective Ventilation Strategies in an Experimental Model of Acute Respiratory Distress Syndrome
- 2017
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Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 45:11, s. e1157-e1164
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare the effects of two lung-protective ventilation strategies on pulmonary vascular mechanics in early acute respiratory distress syndrome.DESIGN: Experimental study.SETTING: University animal research laboratory.SUBJECTS: Twelve pigs (30.8 ± 2.5 kg).INTERVENTIONS: Acute respiratory distress syndrome was induced by repeated lung lavages and injurious mechanical ventilation. Thereafter, animals were randomized to 4 hours ventilation according to the Acute Respiratory Distress Syndrome Network protocol or to an open lung approach strategy. Pressure and flow sensors placed at the pulmonary artery trunk allowed continuous assessment of pulmonary artery resistance, effective elastance, compliance, and reflected pressure waves. Respiratory mechanics and gas exchange data were collected.MEASUREMENTS AND MAIN RESULTS: Acute respiratory distress syndrome led to pulmonary vascular mechanics deterioration. Four hours after randomization, pulmonary vascular mechanics was similar in Acute Respiratory Distress Syndrome Network and open lung approach: resistance (578 ± 252 vs 626 ± 153 dyn.s/cm; p = 0.714), effective elastance, (0.63 ± 0.22 vs 0.58 ± 0.17 mm Hg/mL; p = 0.710), compliance (1.19 ± 0.8 vs 1.50 ± 0.27 mL/mm Hg; p = 0.437), and reflection index (0.36 ± 0.04 vs 0.34 ± 0.09; p = 0.680). Open lung approach as compared to Acute Respiratory Distress Syndrome Network was associated with improved dynamic respiratory compliance (17.3 ± 2.6 vs 10.5 ± 1.3 mL/cm H2O; p < 0.001), driving pressure (9.6 ± 1.3 vs 19.3 ± 2.7 cm H2O; p < 0.001), and venous admixture (0.05 ± 0.01 vs 0.22 ± 0.03, p < 0.001) and lower mean pulmonary artery pressure (26 ± 3 vs 34 ± 7 mm Hg; p = 0.045) despite of using a higher positive end-expiratory pressure (17.4 ± 0.7 vs 9.5 ± 2.4 cm H2O; p < 0.001). Cardiac index, however, was lower in open lung approach (1.42 ± 0.16 vs 2.27 ± 0.48 L/min; p = 0.005).CONCLUSIONS: In this experimental model, Acute Respiratory Distress Syndrome Network and open lung approach affected pulmonary vascular mechanics similarly. The use of higher positive end-expiratory pressures in the open lung approach strategy did not worsen pulmonary vascular mechanics, improved lung mechanics, and gas exchange but at the expense of a lower cardiac index.
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