| 1. |
- Beal, Jacob, et al.
(författare)
-
Robust estimation of bacterial cell count from optical density
- 2020
-
Ingår i: Communications Biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 3:1
-
Tidskriftsartikel (refereegranskat)abstract
- Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data.
|
|
| 2. |
|
|
| 3. |
-
- 2019
-
Tidskriftsartikel (refereegranskat)
|
|
| 4. |
- Akiyama, Kazunori, et al.
(författare)
-
The persistent shadow of the supermassive black hole of M 87: I. Observations, calibration, imaging, and analysis*
- 2024
-
Ingår i: Astronomy and Astrophysics. - 0004-6361 .- 1432-0746. ; 681
-
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.
|
|
| 5. |
- Kim, Jae-Young, et al.
(författare)
-
Event Horizon Telescope imaging of the archetypal blazar 3C 279 at an extreme 20 microarcsecond resolution
- 2020
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 640
-
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.
|
|
| 6. |
- Lu, R.S., et al.
(författare)
-
A ring-like accretion structure in M87 connecting its black hole and jet
- 2023
-
Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 616:7958, s. 686-690
-
Tidskriftsartikel (refereegranskat)abstract
- The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation1,2. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole3. Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of [Formula: see text] Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects, in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow.
|
|
| 7. |
- Cheng, Wan-Lin, et al.
(författare)
-
Quality of life and care burden among family caregivers of people with severe mental illness : mediating effects of self-esteem and psychological distress
- 2022
-
Ingår i: BMC Psychiatry. - : BioMed Central (BMC). - 1471-244X. ; 22:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background Family caregivers are important allies for healthcare providers in facilitating the recovery process among people with mental illness (PWMI). The present study examined the factors associated with quality of life (QoL) among family caregivers of PWMI. Methods A multi-center cross-sectional survey was conducted. Family caregivers of people with schizophrenia, major depressive disorder, and bipolar disorder were recruited using convenience sampling. A survey assessing their QoL, depression, anxiety, and self-esteem was completed with self-rated psychometric scales including the Rosenberg Self-Esteem Scale, Caregiver Burden Inventory, Taiwanese Depression Questionnaire, Beck Anxiety Inventory, and World Health Organization Quality of Life Instrument Short Form. A mediation model was constructed with QoL as the dependent variable, care burden as the independent variable, and psychological distress (including depression and anxiety) with self-esteem as mediating variables. Results Family caregivers of people with schizophrenia had worse QoL compared with counterparts of people with major depression and bipolar disorder. The sociodemographic of both caregivers and PWMI had less impact on QoL when psychological factors were considered. Caregivers with lower self-esteem, higher levels of psychological distress, and heavier care burdens had poorer QoL. Care burden had a significant total effect on QoL. Both self-esteem and psychological distress were significant mediators. Conclusion The findings indicated that caregivers' psychological health and care burden influenced their QoL. Interventions that target family caregivers' self-esteem and psychological distress may attenuate the effect from care burden, and further improve their QoL.
|
|
| 8. |
- Akiyama, Kazunori, et al.
(författare)
-
First Sagittarius A* Event Horizon Telescope Results. IV. Variability, Morphology, and Black Hole Mass
- 2022
-
Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2
-
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.
|
|
| 9. |
- Chan, Ding Cheng Derrick, et al.
(författare)
-
Consensus on best practice standards for Fracture Liaison Service in the Asia-Pacific region
- 2018
-
Ingår i: Archives of Osteoporosis. - : Springer Science and Business Media LLC. - 1862-3522 .- 1862-3514. ; 13:1
-
Tidskriftsartikel (refereegranskat)abstract
- Summary: The Fracture Liaison Service (FLS) Consensus Meeting endorsed by the International Osteoporosis Foundation (IOF), Asian Federation of Osteoporosis Societies (AFOS), and Asia Pacific Osteoporosis Foundation (APOF) was hosted by the Taiwanese Osteoporosis Association on October 14, 2017. International and domestic experts reviewed the 13 Best Practice Framework (BPF) standards and concluded that all standards were generally applicable in the Asia-Pacific region and needed only minor modifications to fit the healthcare settings in the region. Purpose: To review and generate consensus on best practices of fracture liaison service (FLS) in the Asia-Pacific (AP) region. Methods: In October 2017, the Taiwanese Osteoporosis Association (TOA) invited experts from the AP region (n = 23), the Capture the Fracture Steering Committee (n = 2), and the USA (n = 1) to join the AP region FLS Consensus Meeting in Taipei. After two rounds of consensus generation, the recommendations on the 13 Best Practice Framework (BPF) standards were reported and reviewed by the attendees. Experts unable to attend the on-site meeting reviewed the draft, made suggestions, and approved the final version. Results: Because the number of FLSs in the region is rapidly increasing, experts agreed that it was timely to establish consensus on benchmark quality standards for FLSs in the region. They also agreed that the 13 BPF standards and the 3 levels of standards were generally applicable, but that some clarifications were necessary. They suggested, for example, that patient and family education be incorporated into the current standards and that communication with the public to promote FLSs be increased. Conclusions: The consensus on the 13 BPF standards reviewed in this meeting was that they were generally applicable and required only a few advanced clarifications to increase the quality of FLSs in the region.
|
|
| 10. |
- Elsayed, Mohamed Hammad, et al.
(författare)
-
Visible-light-driven hydrogen evolution using nitrogen-doped carbon quantum dot-implanted polymer dots as metal-free photocatalysts
- 2021
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373. ; 283
-
Tidskriftsartikel (refereegranskat)abstract
- Given the photocatalytic properties of semiconducting polymers and carbon quantum dots (CQDs), we report a new structure for a metal-free photocatalytic system with a promising efficiency for hydrogen production through the combination of an organic semiconducting polymer (PFTBTA) and N-doped carbon quantum dots (NCQDs) covered by PS-PEGCOOH to produce heterostructured photocatalysts in the form of polymer dots (Pdots). This design could provide strong interactions between the two materials owing to the space confinement effect in nanometer-sized Pdots. Small particle size NCQDs are easy to insert inside the Pdot, which leads to an increase in the stability of the Pdot structure and enhances the hydrogen evolution rate by approximately 5-fold over that of pure PFTBTA Pdots. The photophysics and the mechanism behind the catalytic activity of our design are investigated by transient absorption measurement, demonstrating the role of NCQDs to enhance the charge separation and the photocatalytic efficiency of the PFTBTA Pdot.
|
|
