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- Bernal, Ximena E., et al.
(författare)
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Empowering Latina scientists
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- Prusakov, Pavel, et al.
(författare)
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A global point prevalence survey of antimicrobial use in neonatal intensive care units : The no-more-antibiotics and resistance (NO-MAS-R) study
- 2021
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Ingår i: eClinicalMedicine. - : Elsevier. - 2589-5370. ; 32
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Tidskriftsartikel (refereegranskat)abstract
- Background: Global assessment of antimicrobial agents prescribed to infants in the neonatal intensive care unit (NICU) may inform antimicrobial stewardship efforts.Methods: We conducted a one-day global point prevalence study of all antimicrobials provided to NICU infants. Demographic, clinical, and microbiologic data were obtained including NICU level, census, birth weight, gestational/chronologic age, diagnoses, antimicrobial therapy (reason for use; length of therapy), antimicrobial stewardship program (ASP), and 30-day in-hospital mortality.Findings: On July 1, 2019, 26% of infants (580/2,265; range, 0-100%; median gestational age, 33 weeks; median birth weight, 1800 g) in 84 NICUs (51, high-income; 33, low-to-middle income) from 29 countries (14, high-income; 15, low-to-middle income) in five continents received >= 1 antimicrobial agent (92%, antibacterial; 19%, antifungal; 4%, antiviral). The most common reasons for antibiotic therapy were "rule-out" sepsis (32%) and "culture-negative" sepsis (16%) with ampicillin (40%), gentamicin (35%), amikacin (19%), vancomycin (15%), and meropenem (9%) used most frequently. For definitive treatment of presumed/confirmed infection, vancomycin (26%), amikacin (20%), and meropenem (16%) were the most prescribed agents. Length of therapy for culture-positive and "culture-negative" infections was 12 days (median; IQR, 8-14) and 7 days (median; IQR, 5-10), respectively. Mortality was 6% (42%, infection-related). An NICU ASP was associated with lower rate of antibiotic utilization (p = 0.02).Interpretation: Global NICU antibiotic use was frequent and prolonged regardless of culture results. NICU-specific ASPs were associated with lower antibiotic utilization rates, suggesting the need for their implementation worldwide.
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| 8. |
- Calcutt, Hannah, 1988, et al.
(författare)
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A high-resolution study of complex organic molecules in hot cores
- 2014
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 443:4, s. 3157-3173
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Tidskriftsartikel (refereegranskat)abstract
- We present the results ofa line identification analysis using data from theIRAMPlateau de Bure Plateau de Bure Interferometer, focusing on six massive star-forming hot cores: G31.41+0.31, tify several transitions of vibrationally excited methyl formate (HCOOCH3) for the first time G29.96−0.02, G19.61−0.23, G10.62−0.38, G24.78+0.08A1 and G24.78+0.08A2.We iden- in these objects as well as transitions of other complex molecules, including ethyl cyanide (C2H5CN), and isocyanic acid (HNCO). We also postulate a detection of one transition of glycolaldehyde (CH2(OH)CHO) in two new hot cores. We find G29.96−0.02, G19.61−0.23, is chemically different: it manifests a larger chemical inventory and has significantly larger col- G24.78+0.08A1 and G24.78+0.08A2 to be chemically very similar. G31.41+0.31, however, umn densities. We suggest that it may represent a different evolutionary stage to the other hot cores in the sample, or it may surround a star with a higher mass. We derive column densities for methyl formate in G31.41+0.31, using the rotation diagram method, of 4 × 1017 cm−2 and methyl formate and methyl cyanide, all seem to trace the same material and peak at roughly a Trot of ∼170 K. For G29.96−0.02, G24.78+0.08A1 and G24.78+0.08A2, glycolaldehyde, the same position towards the dust emission peak. For G31.41+0.31, however, glycolaldehyde shows a different distribution to methyl formate and methyl cyanide and seems to trace the densest, most compact inner part of hot cores.
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| 9. |
- Fedriani, Rubén, 1991, et al.
(författare)
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The SOFIA Massive (SOMA) Star Formation Survey. IV. Isolated Protostars
- 2023
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 942:1
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Tidskriftsartikel (refereegranskat)abstract
- We present similar to 10-40 mu m SOFIA-FORCAST images of 11 isolated protostars as part of the SOFIA Massive (SOMA) Star Formation Survey, with this morphological classification based on 37 mu m imaging. We develop an automated method to define source aperture size using the gradient of its background-subtracted enclosed flux and apply this to build spectral energy distributions (SEDs). We fit the SEDs with radiative transfer models, developed within the framework of turbulent core accretion (TCA) theory, to estimate key protostellar properties. Here, we release the sedcreator python package that carries out these methods. The SEDs are generally well fitted by the TCA models, from which we infer initial core masses M ( c ) ranging from 20-430 M (circle dot), clump mass surface densities sigma(cl) similar to 0.3-1.7 g cm(-2), and current protostellar masses m (*) similar to 3-50 M (circle dot). From a uniform analysis of the 40 sources in the full SOMA survey to date, we find that massive protostars form across a wide range of clump mass surface density environments, placing constraints on theories that predict a minimum threshold sigma(cl) for massive star formation. However, the upper end of the m (*)-sigma(cl) distribution follows trends predicted by models of internal protostellar feedback that find greater star formation efficiency in higher sigma(cl) conditions. We also investigate protostellar far-IR variability by comparison with IRAS data, finding no significant variation over an similar to 40 yr baseline.
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| 10. |
- Gorai, Prasanta, 1991, et al.
(författare)
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Astrochemical Diagnostics of the Isolated Massive Protostar G28.20-0.05
- 2024
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Ingår i: Astrophysical Journal. - 1538-4357 .- 0004-637X. ; 960:2
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Tidskriftsartikel (refereegranskat)abstract
- We study the astrochemical diagnostics of the isolated massive protostar G28.20-0.05. We analyze data from Atacama Large Millimeter/submillimeter Array 1.3 mm observations with a resolution of 0.″2 (∼1000 au). We detect emission from a wealth of species, including oxygen-bearing (e.g., H2CO, CH3OH, CH3OCH3), sulfur-bearing (SO2, H2S), and nitrogen-bearing (e.g., HNCO, NH2CHO, C2H3CN, C2H5CN) molecules. We discuss their spatial distributions, physical conditions, correlation between different species, and possible chemical origins. In the central region near the protostar, we identify three hot molecular cores (HMCs). HMC1 is part of a millimeter continuum ring-like structure, is closest in projection to the protostar, has the highest temperature of ∼300 K, and shows the most line-rich spectra. HMC2 is on the other side of the ring, has a temperature of ∼250 K, and is of intermediate chemical complexity. HMC3 is further away, ∼3000 au in projection, cooler (∼70 K), and is the least line-rich. The three HMCs have similar mass surface densities (∼10 g cm−2), number densities (n H ∼ 109 cm−3), and masses of a few solar masses. The total gas mass in the cores and in the region out to 3000 au is ∼25 M ⊙, which is comparable to that of the central protostar. Based on spatial distributions of peak line intensities as a function of excitation energy, we infer that the HMCs are externally heated by the protostar. We estimate column densities and abundances of the detected species and discuss the implications for hot core astrochemistry.
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| 11. |
- Liu, Mengyao, et al.
(författare)
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The SOFIA Massive (SOMA) Star Formation Survey. II. High Luminosity Protostars
- 2019
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 874:1
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Forskningsöversikt (refereegranskat)abstract
- We present multiwavelength images observed with SOFIA-FORCAST from similar to 10 to 40 mu m of seven high luminosity massive protostars, as part of the SOFIA Massive Star Formation Survey. Source morphologies at these wavelengths appear to be influenced by outflow cavities and extinction from dense gas surrounding the protostars. Using these images, we build spectral energy distributions (SEDs) of the protostars, also including archival data from Spitzer, Herschel, and other facilities. Radiative transfer (RT) models of Zhang & Tan, based on Turbulent Core Accretion theory, are then fit to the SEDs to estimate key properties of the protostars. Considering the best five models fit to each source, the protostars have masses m* similar to 12-64 M circle dot accreting at rates of m* similar to 10(-4) -10(-3) M circle dot yr(-1) inside cores of initial masses M-c similar to 100-500 M circle dot embedded in clumps with mass surface densities Sigma(cl) similar to 0.1-3 g cm(-2) and span a luminosity range of 10(4) -10(6) L circle dot. Compared with the first eight protostars in Paper I, the sources analyzed here are more luminous and, thus, likely to be more massive protostars. They are often in a clustered environment or have a companion protostar relatively nearby. From the range of parameter space of the models, we do not see any evidence that Sigma(cl) needs to be high to form these massive stars. For most sources, the RT models provide reasonable fits to the SEDs, though the cold clump material often influences the long wavelength fitting. However, for sources in very clustered environments, the model SEDs may not be such a good description of the data, indicating potential limitations of the models for these regions.
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| 12. |
- Liu, Mengyao, et al.
(författare)
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The SOFIA Massive (SOMA) Star Formation Survey. III. From Intermediate- to High-mass Protostars
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 904:1
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Tidskriftsartikel (refereegranskat)abstract
- We present similar to 10-40 mm SOFIA-FORCAST images of 14 intermediate-mass protostar candidates as part of the SOFIA Massive (SOMA) Star Formation Survey. We build spectral energy distributions, also using archival Spitzer, Herschel, and IRAS data. We then fit the spectral energy distributions with radiative transfer models of Zhang & Tan, based on turbulent core accretion theory, to estimate key protostellar properties. With the addition of these intermediate-mass sources, based on average properties derived from SED fitting, SOMA protostars span luminosities from similar to 10(2) to 10(6) L-circle dot, current protostellar masses from similar to 0.5 to 35 M-circle dot, and ambient clump mass surface densities, Scl, from 0.1 to g cm(-2). A wide range of evolutionary states of the individual protostars and of the protocluster environments is also probed. We have also considered about 50 protostars identified in infrared dark clouds that are expected to be at the earliest stages of their evolution. With this global sample, most of the evolutionary stages of high- and intermediate-mass protostars are probed. The best-fitting models show no evidence that a threshold value of the protocluster clump mass surface density is required to form protostars up to similar to 25 M.. However, to form more massive protostars, there is tentative evidence that Sigma(cl) needs to be greater than or similar to 1 g cm(-2). We discuss how this is consistent with expectations from core accretion models that include internal feedback from the forming massive star.
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| 13. |
- Ruiz-Solani, N., et al.
(författare)
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Arabidopsis metacaspase MC1 localizes in stress granules, clears protein aggregates, and delays senescence
- 2023
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Ingår i: Plant Cell. - 1040-4651. ; 35:9, s. 3325-3344
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Tidskriftsartikel (refereegranskat)abstract
- The Arabidopsis metacaspase MC1 is recruited to stress granules upon proteotoxic stress, participates in clearance of pathological protein aggregates, and delays senescence. Stress granules (SGs) are highly conserved cytoplasmic condensates that assemble in response to stress and contribute to maintaining protein homeostasis. These membraneless organelles are dynamic, disassembling once the stress is no longer present. Persistence of SGs due to mutations or chronic stress has been often related to age-dependent protein-misfolding diseases in animals. Here, we find that the metacaspase MC1 is dynamically recruited into SGs upon proteotoxic stress in Arabidopsis (Arabidopsis thaliana). Two predicted disordered regions, the prodomain and the 360 loop, mediate MC1 recruitment to and release from SGs. Importantly, we show that MC1 has the capacity to clear toxic protein aggregates in vivo and in vitro, acting as a disaggregase. Finally, we demonstrate that overexpressing MC1 delays senescence and this phenotype is dependent on the presence of the 360 loop and an intact catalytic domain. Together, our data indicate that MC1 regulates senescence through its recruitment into SGs and this function could potentially be linked to its remarkable protein aggregate-clearing activity.
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| 14. |
- Zhang, Yichen, et al.
(författare)
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Discovery of a Photoionized Bipolar Outflow toward the Massive Protostar G45.47+0.05
- 2019
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 886:1
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Tidskriftsartikel (refereegranskat)abstract
- Massive protostars generate strong radiation feedback, which may help set the mass that they achieve by the end of the accretion process. Studying such feedback is therefore crucial for understanding the formation of massive stars. We report the discovery of a photoionized bipolar outflow toward the massive protostar G45.47+0.05 using high-resolution observations at 1.3 mm with the Atacama Large Millimeter/Submillimeter Array (ALMA) and at 7 mm with the Karl G. Jansky Very Large Array (VLA). By modeling the free-free continuum, the ionized outflow is found to be a photoevaporation flow with an electron temperature of 10,000 K and an electron number density of similar to 1.5 x 10(7) cm(-3) at the center, launched from a disk of radius of 110 au. H30 alpha hydrogen recombination line emission shows strong maser amplification, with G45 being one of very few sources to show such millimeter recombination line masers. The mass of the driving source is estimated to be 30-50 M based on the derived ionizing photon rate, or 30-40 M based on the H30 alpha kinematics. The kinematics of the photoevaporated material is dominated by rotation close to the disk plane, while accelerated to outflowing motion above the disk plane. The mass loss rate of the photoevaporation outflow is estimated to be similar to(2-3.5) x 10(-5) M yr(-1). We also found hints of a possible jet embedded inside the wide-angle ionized outflow with nonthermal emissions. The possible coexistence of a jet and a massive photoevaporation outflow suggests that, in spite of the strong photoionization feedback, accretion is still ongoing.
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| 15. |
- Zhang, Yichen, et al.
(författare)
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Dynamics of a massive binary at birth
- 2019
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Ingår i: Nature Astronomy. - : Springer Science and Business Media LLC. - 2397-3366. ; 3:6, s. 517-523
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Almost all massive stars have bound stellar companions, existing in binaries or higher-order multiples(1-5). While binarity is theorized to be an essential feature of how massive stars form(6), essentially all information about such properties is derived from observations of already formed stars, whose orbital properties may have evolved since birth. Little is known about binarity during formation stages. Here we report high-angular-resolution observations of 1.3 mm continuum and H30 alpha recombination line emission, which reveal a massive protobinary with apparent separation of 180 au at the centre of the massive star-forming region IRAS 07299-1651. From the line-of-sight velocity difference of 9.5 km s(-1) of the two protostars, the binary is estimated to have a minimum total mass of 18 solar masses, consistent with several other metrics, and maximum period of 570 yr, assuming a circular orbit. The H30 alpha line from the primary protostar shows kinematics consistent with rotation along a ring of radius of 12 au. The observations indicate that disk fragmentation at several hundred astronomical units may have formed the binary, and much smaller disks are feeding the individual protostars.
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