702 research outputs found
From the ashes: JVLA observations of water fountain nebula candidates show the rebirth of IRAS 18455+0448
[abridged] The class of water fountain nebulae is thought to represent the
stage of the earliest onset of collimated bipolar outflows during the
post-Asymptotic Giant Branch phase. They thus play a crucial role in the study
of the formation of bipolar Planetary Nebulae (PNe). To date, 14 water fountain
nebulae have been identified. The identification of more sources in this unique
stage of stellar evolution will enable us to study the origin of bipolar PNe
morphologies in more detail. We present the results of seven sources observed
with the JVLA that were identified as water fountain candidates in an
Effelsberg 100m telescope survey of 74 AGB and early post-AGB stars. We find
that our sample of water fountain candidates displays strong variability in
their 22 GHz H2O maser spectra. The JVLA observations show an extended bipolar
H2O maser outflow for one source, the OH/IR star IRAS 18455+0448. This source
was previously classified as a 'dying' OH/IR star based on the exponential
decrease of its 1612 MHz OH maser and the lack of H2O masers. We therefore also
re-observed the 1612, 1665, and 1667 MHz OH masers. We confirm that the 1612
MHz masers have not reappeared and find that the 1665/1667 MHz masers have
decreased in strength by several orders of magnitude during the last decade.
The OH/IR star IRAS 18455+0448 is confirmed to be a new addition to the class
of water fountain nebulae. Its kinematic age is approximately 70 yr, but could
be lower, depending on the distance and inclination. Previous observations
indicate, with significant uncertainty, that IRAS 18455+0448 has a surprisingly
low mass compared to available estimates for other water fountain nebulae. The
available historical OH maser observations make IRAS 18455+0448 unique for the
study of water fountain nebulae and the launch of post-AGB bipolar outflows...Comment: 8 pages, 5 figures, accepted for publication in A&A (revised minor
typos
A comprehensive mental health care system for Native Americans in New Mexico. A report of the Native American Mental Health Planning Project.
This is a comprehensive report of a seven-month study contracted through the State Division of Mental Health to the University of New Mexico, Department of Psychiatry/Center on Alcoholism, Substance Abuse and Addictions (CASAA). A select committee of representatives from New Mexico tribes, appropriate state and federal agencies, private entities, and consumers provided input for the project. The final plan is based on the collection and triangulation of a variety of sources. The primary sources utilized in this document included: 1) literature review; 2) indirect measure of the magnitude of alcohol, drug abuse, and mental health needs using selected measures from current census data; 3) extensive survey of current agencies providing services; 4) clinical programming survey to select from optional mental health care delivery system models and a prioritization of services needed; 5) ideas, visions, suggestions and recommendations of selected committees; and 6) private interviews and focus group discussions with tribal members, service workers, and tribal leaders. The plan provides information on: 1) epidemiology of mental health problems; 2) programmatic issues for mental health services; 3) needs assessment studies and findings; 4) system and program design; 5) program development and management; 6) physical plant requirements; 7) management information system; and 8) ten-year implementation process. Based on the findings of this planning effort, a system of comprehensive mental health care for American Indians was proposed. This continuum of care extends from the tribal communities, to regional centers of care, and to a centralized facility
Ultracompact HII regions with extended emission: The complete view
\ua9 2019 The Author(s). In this paper, we present the results of a morphological study performed on a sample of 28 ultracompact HII (UC HII) regions located near extended free-free emission, using radio continuum (RC) observations at 3.6 cm with the C and D Very Large Array (VLA) configurations, with the aim of determining a direct connection between them. By using previously published observations in B and D VLA configurations, we compiled a final catalogue of 21 UC HII regions directly connected with the surrounding extended emission (EE). The observed morphology of most of the UC HII regions in RC emission is irregular (single- or multipeaked sources) and resembles a classical bubble structure in the Galactic plane with well-defined cometary arcs. RC images superimposed on colour composite Spitzer images reinforce the assignations of direct connection by the spatial coincidence between the UC components and regions of saturated 24 ÎŒm emission. We also find that the presence of EE may be crucial to understand the observed infrared excess because an underestimation of ionizing Lyman photons was considered in previous works (e.g. Wood & Churchwell; Kurtz, Churchwell & Wood)
Synthesis of graphene-encapsulated Fe3C/Fe catalyst supported on Sporopollenin exine capsules, and its use for the reverse water gas shift reaction
Bioderived materials have emerged as sustainable catalyst supports for several heterogeneous reactions owing to their naturally occurring hierarchal pore size distribution, high surface area, and thermal and chemical stability. We utilize sporopollenin exine capsules (SpECs), a carbon-rich byproduct of pollen grains, composed primarily of polymerized and cross-linked lipids, to synthesize carbon-encapsulated iron nanoparticles via evaporative precipitation and pyrolytic treatments. The composition and morphology of the macroparticles were influenced by the precursor iron acetate concentration. Most significantly, the formation of crystalline phases (Fe3C, α-Fe, and graphite) detected via X-ray diffraction spectroscopy showed a critical dependence on iron loading. Significantly, the characteristic morphology and structure of the SpECs were largely preserved after high-temperature pyrolysis. Analysis of BrunauerâEmmettâTeller surface area, the D and G bands from Raman spectroscopy, and the relative ratio of the CâC to CâC bonding from high-resolution X-ray photoelectron spectroscopy suggests that porosity, surface area, and degree of graphitization were easily tuned by varying the Fe loading. A mechanism for the formation of crystalline phases and meso-porosity during the pyrolysis process is also proposed. SpEC-Fe10% proved to be highly active and selective for the reverse waterâgas shift reaction at high temperatures (>600 °C)
A collimated, ionized bipolar structure and a high density torus in the young planetary nebula IRAS 17347-3139
We present observations of continuum (lambda = 0.7, 1.3, 3.6 and 18 cm) and
OH maser (lambda = 18 cm) emission toward the young planetary nebula IRAS
17347-3139, which is one of the three planetary nebulae that are known to
harbor water maser emission. From the continuum observations we show that the
ionized shell of IRAS 17347-3139 consists of two main structures: one extended
(size ~1". 5) with bipolar morphology along PA=-30 degrees, elongated in the
same direction as the lobes observed in the near-infrared images, and a central
compact structure (size ~0". 25) elongated in the direction perpendicular to
the bipolar axis, coinciding with the equatorial dark lane observed in the
near-infrared images. Our image at 1.3 cm suggests the presence of dense walls
in the ionized bipolar lobes. We estimate for the central compact structure a
value of the electron density at least ~5 times higher than in the lobes. A
high resolution image of this structure at 0.7 cm shows two peaks separated by
about 0". 13 (corresponding to 100-780 AU, using a distance range of 0.8-6
kpc). This emission is interpreted as originating in an ionized equatorial
torus-like structure, from whose edges the water maser emission might be
arising. We have detected weak OH 1612 MHz maser emission at VLSR ~ -70 km/s
associated with IRAS 17347-3139. We derive a 3 sigma upper limit of < 35% for
the percentage of circularly polarized emission. Within our primary beam, we
detected additional OH 1612 MHz maser emission in the LSR velocity ranges -5 to
-24 and -90 to -123 km/s, associated with the sources 2MASS J17380406-3138387
and OH 356.65-0.15, respectively.Comment: 26 pages, 8 figures. Accepted for publication in Ap
Ultracompact HII regions with extended emission: The case of G43.89-0.78 and its molecular environment
The Karl Jansky Very Large Array (VLA), Owens Valley Radio Observatory
(OVRO), Atacama Large Millimetric Array (ALMA), and the infrared
\textit{Spitzer} observatories, are powerful facilities to study massive star
formation regions and related objects such as ultra--compact (UC) \hii regions,
molecular clumps, and cores. We used these telescopes to study the \uchiir
G43.89--0.78. The morphological study at arcminute scales using NVSS and
\textit{Spitzer} data shows that this region is similar to those observed in
the \textit{ bubble--like} structures revealed by \textit{Spitzer}
observations. With this result, and including a physical characterization based
on 3.6 cm data, we suggest G43.89--0.78 be classified as an \uchiir with
Extended Emission because it meets the operational definition given in this
paper comparing radio continuum data at 3.6 and 20~cm. For the ultra-compact
component, we use VLA data to obtain physical parameters at 3.6~cm confirming
this region as an \uchii region. Using ALMA observations, we detect the
presence of a dense ( cm) and small ( 2.0\arcsec;
0.08 pc) molecular clump with a mass of 220 M and average kinetic
temperature of 21~K, located near to the \uchii region. In this clump,
catalogued as G43.890--0.784, water masers also exist, possibly tracing a
bipolar outflow. We discover in this vicinity two additional clumps which we
label as G43.899--0.786 (T = 50 K; M = 11 M), and G43.888--0.787
(T = 50 K; M = 15 M).Comment: 13 pages, 8 figures, 2 tables. Accepted for publication in the
Monthly Notices of the Royal Astronomical Society Main Journal (2020
The magnetic field toward the young planetary nebula K~3-35
K 3-35 is a planetary nebula (PN) where H2O maser emission has been detected,
suggesting that it departed from the proto-PNe phase only some decades ago.
Interferometric VLA observations of the OH 18 cm transitions in K~3-35 are
presented.OH maser emission is detected in all four ground state lines (1612,
1665, 1667, and 1720 MHz). All the masers appear blueshifted with respect to
the systemic velocity of the nebula and they have different spatial and
kinematic distributions.The OH 1665 and 1720 MHz masers appear spatially
coincident with the core of the nebula, while the OH 1612 and 1667 MHz ones
exhibit a more extended distribution. We suggest that the 1665 and 1720 masers
arise from a region close to the central star, possibly in a torus, while the
1612 and 1667 lines originate mainly from the extended northern lobe of the
outflow. It is worth noting that the location and velocity of the OH 1720 MHz
maser emission are very similar to those of the H2O masers (coinciding within
0.1" and ~2 km/s, respectively). We suggest that the pumping mechanism in the
H2O masers could be produced by the same shock that is exciting the OH 1720 MHz
transition. A high degree of circular polarization (>50%) was found to be
present in some features of the 1612, 1665, and 1720 MHz emission.For the 1665
MHz transition at ~ +18 km/s the emission with left and right circular
polarizations (LCP and RCP) coincide spatially within a region of ~0.03" in
diameter.Assuming that these RCP and LCP 1665 features come from a Zeeman pair,
we estimate a magnetic field of ~0.9 mG within 150 AU from the 1.3 cm continuum
peak. This value is in agreement with a solar-type magnetic field associated
with evolved stars.Comment: 6 pages, 2 tables, 4 figures, ApJ accepte
Headache, Delirium or Encephalitis?:A Case of Residual Mutism Secondary to Anti-NMDA Receptor Encephalitis
Encephalitis is a heterogeneous syndrome that is diagnosed through clinical assessment and the assistance of laboratory, neuroimaging and electroencephalographic workup. Over the past 10 years, autoimmune encephalitis has been more frequently recognized; however, most reports come from highly specialized hospital settings. Anti-N-methyl-D-aspartate receptor (NDMAR) encephalitis has been associated with paraneoplastic encephalitis syndromes and was first recognized in 2005. We present the case of a 34-year-old male patient who debuted clinically with a headache associated with neuropsychiatric symptoms (i.e., visual and auditory hallucinations, anxiety, aggressiveness) and memory deficits, progressing to autonomic dysfunction (i.e., tachycardia and hypertension), seizures, and stupor with catatonic features. Initially, infectious, metabolic, and toxicological etiologies were excluded; followed by the assessment of immunological and paraneoplastic etiologies, yielding positive IgG levels for anti-NMDAR antibodies. The patient was treated successfully with systemic steroid therapy and therapeutic plasmapheresis, while mutism was the only sequela. Although large case series reporting on paraneoplastic and autoimmune anti-NMDAR encephalitis have been reported in the literature in recent years, this case is of particular importance due to the stepwise differential diagnosis and treatment management procedure that was used in a regional but not highly specialized hospital setting
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