The massive star-forming region G332.83-0.55 contains at least two levels of hub-filament structures. The hub-filament structures may form through the “gravitational focusing” process. ...High-resolution LAsMA and ALMA observations can directly trace the gas inflows from cloud to core scales. We investigated the effects of shear and tides from the protocluster on the surrounding local dense gas structures. Our results seem to deny the importance of shear and tides from the protocluster. However, for a gas structure, it bears the tidal interactions from all external material, not only the protocluster. To fully consider the tidal interactions, we derived the tide field according to the surface density distribution. Then, we used the average strength of the external tidal field of a structure to measure the total tidal interactions that are exerted on it. For comparison, we also adopted an original pixel-by-pixel computation to estimate the average tidal strength for each structure. Both methods give comparable results. After considering the total tidal interactions, for the scaling relation between the velocity dispersion σ, the effective radius R , and the column density N of all the structures, the slope of the σ − N * R relation changes from 0.20 ± 0.04 to 0.52 ± 0.03, close to 0.5 of the pure free-fall gravitational collapse, and the correlation also becomes stronger. Thus, the deformation due to the external tides can effectively slow down the pure free-fall gravitational collapse of gas structures. The external tide tries to tear up the structure, but the external pressure on the structure prevents this process. The counterbalance between the external tide and external pressure hinders the free-fall gravitational collapse of the structure, which can also cause the pure free-fall gravitational collapse to be slowed down. These mechanisms can be called “tide-regulated gravitational collapse”.
We present molecular line observations, made with angular resolutions of {approx}20'', toward the filamentary infrared dark cloud G34.43+0.24 using the APEX CO(3 {yields} 2), {sup 13}CO(3 {yields} ...2), C{sup 18}O(3 {yields} 2), and CS(7 {yields} 6) transitions, Nobeyama 45 m CS(2 {yields} 1), SiO(2 {yields} 1), C{sup 34}S(2 {yields} 1), HCO{sup +}(1 {yields} 0), H{sup 13}CO{sup +}(1 {yields} 0), and CH{sub 3}OH(2 {yields} 1) transitions, and SEST CS(2 {yields} 1) and C{sup 18}O(2 {yields} 1) transitions telescopes. We find that the spatial distribution of the molecular emission is similar to that of the dust continuum emission observed with 11'' resolution showing a filamentary structure and four cores. The cores have local thermodynamic equilibrium masses ranging from 3.3 x 10{sup 2} to 1.5 x 10{sup 3} M{sub sun} and virial masses from 1.1 x 10{sup 3} to 1.5 x 10{sup 3} M{sub sun}, molecular hydrogen densities between 1.8 x 10{sup 4} and 3.9 x 10{sup 5} cm{sup -3}, and column densities >2.0 x 10{sup 22} cm{sup -2}, values characteristic of massive star-forming cores. The {sup 13}CO(3 {yields} 2) profile observed toward the most massive core reveals a blue profile indicating that the core is undergoing large-scale inward motion with an average infall velocity of 1.3 km s{sup -1} and a mass infall rate of 1.8 x 10{sup -3} M{sub sun} yr{sup -1}. We report the discovery of a molecular outflow toward the northernmost core thought to be in a very early stage of evolution. We also detect the presence of high-velocity gas toward each of the other three cores, giving support to the hypothesis that the excess 4.5 {mu}m emission ('green fuzzies') detected toward these cores is due to shocked gas. The molecular outflows are massive and energetic, with masses ranging from 25 to 80 M{sub sun}, momentum 2.3-6.9 x 10{sup 2} M{sub sun} km s{sup -1}, and kinetic energies 1.1-3.6 x 10{sup 3} M{sub sun} km{sup 2} s{sup -2}, indicating that they are driven by luminous, high-mass young stellar objects.
We present a catalog of 315 protostellar outflow candidates detected in SiO J=5-4 in the ALMA-IMF Large Program, observed with ~2000 au spatial resolution, 0.339 km/s velocity resolution, and 2-12 ...mJy/beam (0.18-0.8 K) sensitivity. We find median outflow masses, momenta, and kinetic energies of ~0.3 M\(_{\odot}\), 4 M\(_{\odot}\) km/s, and 10\(^{45}\) erg, respectively. Median outflow lifetimes are 6,000 years, yielding median mass, momentum, and energy rates of \(\dot{M}\) = 10\(^{-4.4}\) M\(_{\odot}\) yr\(^{-1}\), \(\dot{P}\) = 10\(^{-3.2}\) M\(_{\odot}\) km/s yr\(^{-1}\), and \(\dot{E}\) = 1 L\(_{\odot}\). We analyze these outflow properties in the aggregate in each field. We find correlations between field-aggregated SiO outflow properties and total mass in cores (~3\(-\)5\(\sigma\)), and no correlations above 3\(\sigma\) with clump mass, clump luminosity, or clump luminosity-to-mass ratio. We perform a linear regression analysis and find that the correlation between field-aggregated outflow mass and total clump mass - which has been previously described in the literature - may actually be mediated by the relationship between outflow mass and total mass in cores. We also find that the most massive SiO outflow in each field is typically responsible for only 15-30% of the total outflow mass (60% upper limit). Our data agree well with the established mechanical force-bolometric luminosity relationship in the literature, and our data extend this relationship up to L \(\geq\) 10\(^6\) L\(_{\odot}\) and \(\dot{P}\) \(\geq\) 1 M\(_{\odot}\) km/s yr\(^{-1}\). Our lack of correlation with clump L/M is inconsistent with models of protocluster formation in which all protostars start forming at the same time.
Abstract
We present a catalog of 315 protostellar outflow candidates detected in SiO
J
= 5 − 4 in the ALMA-IMF Large Program, observed with ∼2000 au spatial resolution, 0.339 km s
−1
velocity ...resolution, and 2–12 mJy beam
−1
(0.18–0.8 K) sensitivity. We find median outflow masses, momenta, and kinetic energies of ∼0.3
M
⊙
, 4
M
⊙
km s
−1
, and 10
45
erg, respectively. Median outflow lifetimes are 6000 yr, yielding median mass, momentum, and energy rates of
M
̇
= 10
−4.4
M
⊙
yr
−1
,
P
̇
= 10
−3.2
M
⊙
km s
−1
yr
−1
, and
E
̇
= 1
L
⊙
. We analyze these outflow properties in the aggregate in each field. We find correlations between field-aggregated SiO outflow properties and total mass in cores (∼3
σ
–5
σ
), and no correlations above 3
σ
with clump mass, clump luminosity, or clump luminosity-to-mass ratio. We perform a linear regression analysis and find that the correlation between field-aggregated outflow mass and total clump mass—which has been previously described in the literature—may actually be mediated by the relationship between outflow mass and total mass in cores. We also find that the most massive SiO outflow in each field is typically responsible for only 15%–30% of the total outflow mass (60% upper limit). Our data agree well with the established mechanical force−bolometric luminosity relationship in the literature, and our data extend this relationship up to
L
≥ 10
6
L
⊙
and
P
̇
≥ 1
M
⊙
km s
−1
yr
−1
. Our lack of correlation with clump
L
/
M
is inconsistent with models of protocluster formation in which all protostars start forming at the same time.
ABSTRACT We have investigated the physical properties of Planck Galactic Cold Clumps (PGCCs) located in the Galactic Plane, using the JCMT Plane Survey (JPS) and the SCUBA-2 Continuum Observations of ...Pre-protostellar Evolution (SCOPE) survey. By utilizing a suite of molecular-line surveys, velocities, and distances were assigned to the compact sources within the PGCCs, placing them in a Galactic context. The properties of these compact sources show no large-scale variations with Galactic environment. Investigating the star-forming content of the sample, we find that the luminosity-to-mass ratio (L/M) is an order of magnitude lower than in other Galactic studies, indicating that these objects are hosting lower levels of star formation. Finally, by comparing ATLASGAL sources that are associated or are not associated with PGCCs, we find that those associated with PGCCs are typically colder, denser, and have a lower L/M ratio, hinting that PGCCs are a distinct population of Galactic Plane sources.
Neuropsychiatric manifestations are serious and frequent complications of systemic lupus erythematous (SLE). Catatonia is a neuropsychiatric disorder characterized by motor disturbance (including ...waxy flexibility and catalepsy), stupor, excitement, negativism, mutism, echopraxia and echolalia. Catatonia associated with SLE has been only rarely reported, especially in children. Here we present a case of a 14-year-old patient encountered in consultation-liaison psychiatry who presented catatonia associated with SLE. Her catatonia was refractory to treatment with pulse methylprednisolone, intravenous cyclophosphamide and rituximab. The patient responded to a combined therapy of electroconvulsive therapy and benzodiazepines. The present case suggests that although rarely reported, catatonia seen in the background of SLE should be promptly identified and treated to reduce the morbidity.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Context.
Although the basic processes of star formation (SF) are known, more research is needed on SF across multiple scales and environments. The
Planck
all-sky survey provided a large catalog of ...Galactic cold clouds and clumps that have been the target of several follow-up surveys.
Aims.
We aim to characterize a diverse selection of dense, potentially star-forming cores, clumps, and clouds within the Milky Way in terms of their dust emission and SF activity.
Methods.
We studied 53 fields that have been observed in the JCMT SCUBA-2 continuum survey SCOPE and have been mapped with
Herschel
. We estimated dust properties by fitting
Herschel
observations with modified blackbody functions, studied the relationship between dust temperature and dust opacity spectral index
β
, and estimated column densities. We extracted clumps from the SCUBA-2 850 μm maps with the FellWalker algorithm and examined their masses and sizes. Clumps are associated with young stellar objects found in several catalogs. We estimated the gravitational stability of the clumps with virial analysis. The clumps are categorized as unbound starless, prestellar, or protostellar.
Results.
We find 529 dense clumps, typically with high column densities from (0.3–4.8) × 10
22
cm
−2
, with a mean of (1.5 ± 0.04) ×10
22
cm
−2
, low temperatures (
T
∼ 10–20 K), and estimated submillimeter
β
= 1.7 ± 0.1. We detect a slight increase in opacity spectral index toward millimeter wavelengths. Masses of the sources range from 0.04
M
⊙
to 4259
M
⊙
. Mass, linear size, and temperature are correlated with distance. Furthermore, the estimated gravitational stability is dependent on distance, and more distant clumps appear more virially bound. Finally, we present a catalog of properties of the clumps.
Conclusions.
Our sources present a large array of SF regions, from high-latitude, nearby diffuse clouds to large SF complexes near the Galactic center. Analysis of these regions will continue with the addition of molecular line data, which will allow us to study the densest regions of the clumps in more detail.
Abstract
In this study, were extensively reviewed the hardening and self-healing properties of Laves-phase in Fe-based alloys. First, the microstructural features of different polytypes of the ...Laves-phase, focusing on the thermodynamics and kinetics of formation in ferritic and martensitic steels were revised. C14 was identified as the dominant polytype in steels, providing strengthening by precipitation, anchoring of dislocation, and interphase boundaries, thereby increasing the creep resistance. Although the Laves phase is widely known as a reinforcement particle (or even a detrimental phase in some systems) in martensitic/ferritic and ferritic steels, recent findings have uncovered a promising property. Particles with self-healing characteristics provide creep resistance by delaying creep cavities formation. In this regard, different elements such as tungsten and molybdenum are known to provide this feature to binary and tertiary ferrous alloys due to their ability to diffuse into the creep cavities and form Laves-phase Fe(Mo,W)
2
. To date, self-healing by precipitation has only been reported in commercial stainless steel AISI 312, 347, and 304 modified with boron, nevertheless with a little contribution to creep rupture life. Although, commercial computational tools with thermodynamic and kinetic databases are available for researchers, to tackle the self-healing process with exactitude, genetic algorithms arise as a new tool for computational design. The two properties of Laves phase reported in the literature, precipitation hardening and self-healing agent, is a mix that can bring out a new research field. Therefore, it is not unreasonable to think of tailor-made high chromium creep-resistant steels reinforced by Laves-phase coupled with self-healing properties. However, owing to the characteristic of Laves-phase seems to be a complex challenge, mainly due to the crystallographic features of this phase in comparison with the host matrix, available computational tools, and databases.
In this study, three martensitic creep-resistant steels with 100, 90, and 70 ppm of boron were investigated. The experimental data obtained from isothermal aging and creep test at 650 °C were ...compared with the results of simulation conducted using TC-PRISMA software. Tungsten was found to be the rate-controlling element in the coarsening of (Cr, Fe, W)
23
C
6
carbides; however, this result differed in terms of boron-containing steel. Several studies indicate that the low solubility of boron in ferrite promotes boron enrichment in (Cr, Fe, W)
23
C
6
carbide, thereby reducing its coarsening rate. However, this mechanism is not universally agreed upon. In the present study, a comparison between experimental and theoretical results revealed that in boron-containing steels, the coarsening of (Cr, Fe, W)
23
C
6
carbide is controlled probably by boron volume diffusion or by trans-interface diffusion.
Graphic Abstract
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