169 research outputs found
Nuclear high-ionisation outflow in the Compton-thick AGN NGC6552 as seen by the JWST mid-infrared instrument
During the commissioning of the James Webb Space Telescope (JWST), the
mid-infrared instrument (MIRI) observed NGC6552 with the MIRI Imager and the
medium-resolution spectrograph (MRS). NGC6552 is an active galactic nucleus
(AGN) at redshift 0.0266 classified as a Seyfert 2 nucleus in the optical, and
Compton-thick AGN in X-rays. This work exemplifies and demonstrates the MRS
capabilities to study the mid-infrared (mid-IR) spectra and characterize the
physical conditions and kinematics of the ionized and molecular gas in the
nuclear regions of nearby galaxies. We obtained the nuclear, circumnuclear, and
central mid-IR spectra of NGC6552. They provide the first clear observational
evidence for a nuclear outflow in NGC6552. The outflow contributes to 677%
of the total line flux independent of the ionization potential (27 to 187 eV)
and critical densities (10 to 410 cm), showing an
average blue-shifted peak velocity of -12745 kms and an outflow
maximal velocity of 69880 kms. Since the mid-IR photons penetrate
dusty regions as efficiently as X-ray keV photons, we interpret these results
as the evidence for a highly ionized, non-stratified, AGN-powered, and fast
outflowing gas in a low density environment (few 10 cm) located
very close (<0.2kpc) to the Compton-thick AGN. Nine pure rotational molecular
Hydrogen lines are detected and spectrally resolved, and exhibit symmetric
Gaussian profiles, consistent with the galactic rotation, and with no evidence
of outflowing H material. We detect a warm H mass of
in the central region (1.8 kpc in diameter) of
the galaxy, with almost 30% of that mass in the circum-nuclear region. Line
ratios confirm that NGC6552 has a Seyfert nucleus with a black hole mass
estimated in the range of 0.6 to 6 million solar masses.Comment: 13 pages, 5 figures, 5 tables, accepted in A&
The diverse chemistry of protoplanetary disks as revealed by JWST
Early results from the JWST-MIRI guaranteed time programs on protostars
(JOYS) and disks (MINDS) are presented. Thanks to the increased sensitivity,
spectral and spatial resolution of the MIRI spectrometer, the chemical
inventory of the planet-forming zones in disks can be investigated with
unprecedented detail across stellar mass range and age. Here data are presented
for five disks, four around low-mass stars and one around a very young
high-mass star. The mid-infrared spectra show some similarities but also
significant diversity: some sources are rich in CO2, others in H2O or C2H2. In
one disk around a very low-mass star, booming C2H2 emission provides evidence
for a ``soot'' line at which carbon grains are eroded and sublimated, leading
to a rich hydrocarbon chemistry in which even di-acetylene (C4H2) and benzene
(C6H6) are detected (Tabone et al. 2023). Together, the data point to an active
inner disk gas-phase chemistry that is closely linked to the physical structure
(temperature, snowlines, presence of cavities and dust traps) of the entire
disk and which may result in varying CO2/H2O abundances and high C/O ratios >1
in some cases. Ultimately, this diversity in disk chemistry will also be
reflected in the diversity of the chemical composition of exoplanets.Comment: 17 pages, 8 figures. Author's version of paper submitted to Faraday
Discussions January 18 2023, Accepted March 16 202
Historical Analysis: Tracking, Problematizing, and Reterritorializing Achievement and the Achievement Gap
For more than a century, state and federal governments and organizations have used different measures to determine if students and groups of students have achieved in a particular subject or grade level. While the construct of achievement is applied irrespective of student differences, this equal application turns out to be anything but equitable. In this chapter, we work to understand the way achievement plays out for Black students by deconstructing how the word achievement works. In doing so, we track the history of education, testing, and curriculum as it has been applied to Black youth and youth of color
JWST MIRI/MRS in-flight absolute flux calibration and tailored fringe correction for unresolved sources
Context. The Medium Resolution Spectrometer (MRS) is one of the four observing modes of JWST/MIRI. Using JWST in-flight data of unresolved (point) sources, we can derive the MRS absolute spectral response function (ASRF) starting from raw data. Spectral fringing, caused by coherent reflections inside the detector arrays, plays a critical role in the derivation and interpretation of the MRS ASRF. The fringe corrections implemented in the current pipeline are not optimal for non-extended sources, and a high density of molecular features particularly inhibits an accurate correction. Aims. In this paper, we present an alternative way to calibrate the MIRI/MRS data. Firstly, we derive a fringe correction that accounts for the dependence of the fringe properties on the MIRI/MRS pupil illumination and detector pixel sampling of the point spread function. Secondly, we derive the MRS ASRF using an absolute flux calibrator observed across the full 5- 28 \ub5m wavelength range of the MRS. Thirdly, we apply the new ASRF to the spectrum of a G dwarf and compare it with the output of the JWST/MIRI default data reduction pipeline. Finally, we examine the impact of the different fringe corrections on the detectability of molecular features in the G dwarf and K giant. Methods. The absolute flux calibrator HD 163466 (A-star) was used to derive tailored point source fringe flats at each of the default dither locations of the MRS. The fringe-corrected point source integrated spectrum of HD 163466 was used to derive the MRS ASRF using a theoretical model for the stellar continuum. A cross-correlation was run to quantify the uncertainty on the detection of CO, SiO, and OH in the K giant and CO in the G dwarf for different fringe corrections. Results. The point-source-tailored fringe correction and ASRF are found to perform at the same level as the current corrections, beating down the fringe contrast to the sub-percent level in the G dwarf in the longer wavelengths, whilst mitigating the alteration of real molecular features. The same tailored solutions can be applied to other MRS unresolved targets. Target acquisition is required to ensure the pointing is accurate enough to apply this method. A pointing repeatability issue in the MRS limits the effectiveness of the tailored fringe flats is at short wavelengths. Finally, resulting spectra require no scaling to make the sub-bands match, and a dichroic spectral leak at 12.2 \ub5m is removed
Observations of the planetary nebula SMP LMC 058 with the JWST MIRI medium resolution spectrometer
During the commissioning of JWST, the medium-resolution spectrometer (MRS) on the mid-infrared instrument (MIRI) observed the planetary nebula SMP LMC 058 in the Large Magellanic Cloud. The MRS was designed to provide medium resolution (R = λ/Δλ) 3D spectroscopy in the whole MIRI range. SMP LMC 058 is the only source observed in JWST commissioning that is both spatially and spectrally unresolved by the MRS and is a good test of JWST's capabilities. The new MRS spectra reveal a wealth of emission lines not previously detected in this planetary nebula. From these lines, the spectral resolving power (λ/Δλ) of the MRS is confirmed to be in the range R = 4000-1500, depending on the MRS spectral sub-band. In addition, the spectra confirm that the carbon-rich dust emission is from complex hydrocarbons and SiC grains and that there is little to no time evolution of the SiC dust and emission line strengths over a 17-yr epoch. These commissioning data reveal the great potential of the MIRI MRS for the study of circumstellar and interstellar material.</p
Race and Equality in the Academy: Rethinking Higher Education Actors and the Struggle for Equality in the Post-World War II Period
Water in the terrestrial planet-forming zone of the PDS 70 disk
Terrestrial and sub-Neptune planets are expected to form in the inner
(AU) regions of protoplanetary disks. Water plays a key role in their
formation, although it is yet unclear whether water molecules are formed
in-situ or transported from the outer disk. So far Spitzer Space Telescope
observations have only provided water luminosity upper limits for dust-depleted
inner disks, similar to PDS 70, the first system with direct confirmation of
protoplanet presence. Here we report JWST observations of PDS 70, a benchmark
target to search for water in a disk hosting a large (AU)
planet-carved gap separating an inner and outer disk. Our findings show water
in the inner disk of PDS 70. This implies that potential terrestrial planets
forming therein have access to a water reservoir. The column densities of water
vapour suggest in-situ formation via a reaction sequence involving O, H,
and/or OH, and survival through water self-shielding. This is also supported by
the presence of CO emission, another molecule sensitive to UV
photodissociation. Dust shielding, and replenishment of both gas and small dust
from the outer disk, may also play a role in sustaining the water reservoir.
Our observations also reveal a strong variability of the mid-infrared spectral
energy distribution, pointing to a change of inner disk geometry.Comment: To appear in Nature on 24 July 2023. 21 pages, 10 figures; includes
extended data. Part of the JWST MINDS Guaranteed Time Observations program's
science enabling products. Spectra downloadable on Zenodo at
https://zenodo.org/record/799102
Role of the Small GTPase Rho3 in Golgi/Endosome Trafficking through Functional Interaction with Adaptin in Fission Yeast
BACKGROUND: We had previously identified the mutant allele of apm1(+) that encodes a homolog of the mammalian µ1A subunit of the clathrin-associated adaptor protein-1 (AP-1) complex, and we demonstrated the role of Apm1 in Golgi/endosome trafficking, secretion, and vacuole fusion in fission yeast. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we isolated rho3(+), which encodes a Rho-family small GTPase, an important regulator of exocystosis, as a multicopy-suppressor of the temperature-sensitive growth of the apm1-1 mutant cells. Overexpression of Rho3 suppressed the Cl(-) sensitivity and immunosuppressant sensitivity of the apm1-1 mutant cells. Overexpression of Rho3 also suppressed the fragmentation of vacuoles, and the accumulation of v-SNARE Syb1 in Golgi/endosomes and partially suppressed the defective secretion associated with apm1-deletion cells. Notably, electron microscopic observation of the rho3-deletion cells revealed the accumulation of abnormal Golgi-like structures, vacuole fragmentation, and accumulation of secretory vesicles; these phenotypes were very similar to those of the apm1-deletion cells. Furthermore, the rho3-deletion cells and apm1-deletion cells showed very similar phenotypic characteristics, including the sensitivity to the immunosuppressant FK506, the cell wall-damaging agent micafungin, Cl(-), and valproic acid. Green fluorescent protein (GFP)-Rho3 was localized at Golgi/endosomes as well as the plasma membrane and division site. Finally, Rho3 was shown to form a complex with Apm1 as well as with other subunits of the clathrin-associated AP-1 complex in a GTP- and effector domain-dependent manner. CONCLUSIONS/SIGNIFICANCE: Taken together, our findings reveal a novel role of Rho3 in the regulation of Golgi/endosome trafficking and suggest that clathrin-associated adaptor protein-1 and Rho3 co-ordinate in intracellular transport in fission yeast. To the best of our knowledge, this study provides the first evidence of a direct link between the small GTPase Rho and the clathrin-associated adaptor protein-1 in membrane trafficking
The long coiled-coil protein NECC2 is associated to caveolae and modulates NGF/TrkA signaling in PC12 cells [corrected].
TrkA-mediated NGF signaling in PC12 cells has been shown to be compartimentalized in specialized microdomains of the plasma membrane, the caveolae, which are organized by scaffold proteins including the member of the caveolin family of proteins, caveolin-1. Here, we characterize the intracellular distribution as well as the biochemical and functional properties of the neuroendocrine long coiled-coil protein 2 (NECC2), a novel long coiled-coil protein selectively expressed in neuroendocrine tissues that contains a predicted caveolin-binding domain and displays structural characteristics of a scaffolding factor. NECC2 distributes in caveolae, wherein it colocalizes with the TrkA receptor, and behaves as a caveolae-associated protein in neuroendocrine PC12 cells. In addition, stimulation of PC12 cells with nerve growth factor (NGF) increased the expression and regulated the distribution of NECC2. Interestingly, knockdown as well as overexpression of NECC2 resulted in a reduction of NGF-induced phosphorylation of the TrkA downstream effector extracellular signal-regulated kinases 1 and 2 (ERK1/ERK2) but not of Akt. Altogether, our results identify NECC2 as a novel component of caveolae in PC12 cells and support the contribution of this protein in the maintenance of TrkA-mediated NGF signaling.journal articleresearch support, non-u.s. gov't20132013 09 06importe
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Linking formal child care characteristics to children's socioemotional well-being: A comparative perspective
Most research on formal child care and children’s outcomes has focused on single countries. We, however, contend that policy context may moderate the association between formal child care characteristics and children’s socioemotional well-being. We examined this by comparing the Netherlands, Finland and the UK; three countries that differ regarding family policies. Of these three countries, Finland was recently ranked highest (ranked 1st) with regards to quality of child care in a recent analysis by the Economist ,followed by the UK (ranked 3rd) and then the Netherlands (ranked 7th) .We hypothesized that children who attend child - care settings in countries with higher- uality formal child- are provision would generally show better socioemotional outcomes. Data from the comparative ‘F amilies 24/7’ survey were used, including 990 parents with children aged 0–12. We distinguished between two age groups in our analysis. Results indicated that, compared to the UK, longer hours in formal care were less beneficial in the Netherlands. Furthermore, spen ding time in formal care during nonstandard hours was more harmful for children in Finland compared to the UK. Lastly, receiving care from multiple caregivers was more disruptive for British children than for Dutch children. No differences were found between Finland and the Netherlands
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