1,423 research outputs found
Massive protostars as gamma-ray sources
Massive protostars have associated bipolar outflows with velocities of
hundreds of km s. Such outflows can produce strong shocks when interact
with the ambient medium leading to regions of non-thermal radio emission. We
aim at exploring under which conditions relativistic particles are accelerated
at the terminal shocks of the protostellar jets and can produce significant
gamma-ray emission. We estimate the conditions necessary for particle
acceleration up to very high energies and gamma-ray production in the
non-thermal hot spots of jets associated with massive protostars embedded in
dense molecular clouds. We show that relativistic Bremsstrahlung and
proton-proton collisions can make molecular clouds with massive young stellar
objects detectable by the {\it Fermi}{} satellite at MeV-GeV energies and by
Cherenkov telescope arrays in the GeV-TeV range. Gamma-ray astronomy can be
used to probe the physical conditions in star forming regions and particle
acceleration processes in the complex environment of massive molecular clouds.Comment: 10 pages, 5 figures, 2 tables, accepted for publication in Astronomy
and Astrophysic
Massive protostars as gamma-ray sources
Massive protostars have associated bipolar outflows with velocities of
hundreds of km s. Such outflows can produce strong shocks when interact
with the ambient medium leading to regions of non-thermal radio emission. We
aim at exploring under which conditions relativistic particles are accelerated
at the terminal shocks of the protostellar jets and can produce significant
gamma-ray emission. We estimate the conditions necessary for particle
acceleration up to very high energies and gamma-ray production in the
non-thermal hot spots of jets associated with massive protostars embedded in
dense molecular clouds. We show that relativistic Bremsstrahlung and
proton-proton collisions can make molecular clouds with massive young stellar
objects detectable by the {\it Fermi}{} satellite at MeV-GeV energies and by
Cherenkov telescope arrays in the GeV-TeV range. Gamma-ray astronomy can be
used to probe the physical conditions in star forming regions and particle
acceleration processes in the complex environment of massive molecular clouds.Comment: 10 pages, 5 figures, 2 tables, accepted for publication in Astronomy
and Astrophysic
An Expanding HI Photodissociated Region Associated with the Compact HII Region G213.880-11.837 in the GGD 14 Complex
We present high angular and spectral resolution HI 21~cm line observations
toward the cometary-shaped compact HII region G213.880-11.837 in the GGD~14
complex.The kinematics and morphology of the photodissociated region, traced by
the HI line emission, reveal that the neutral gas is part of an expanding flow.
The kinematics of the HI gas along the major axis of G213.880-11.837 shows that
the emission is very extended toward the SE direction, reaching LSR radial
velocities in the tail of about 14 km/s. The ambient LSR radial velocity of the
molecular gas is 11.5 km/s, which suggests a champagne flow of the HI gas. This
is the second (after G111.61+0.37) cometary HII/HI region known.Comment: Accepted for publication in the Astronomical Journal (10 pages, 4
figures, 1 table
Clinical, imaging and genetic analysis of double bilateral radix entomolaris
Background: Anatomy describes that first mandibular molars have two roots: 1 mesial, with 2 root canals, and 1 distal, with 1 root canal. The presence of three roots in these teeth is uncommon. Root anatomical variations have an impact, especially in endodontic, where the highest rates of nonsurgical treatment failures are due to the inability to identify and access roots and/or accessory canals. The aim of this research is to report a case of double three-rooted mandibular first molar through clinical, imaging and genetic analysis. Materials and methods: Using a panoramic radiography, the presence of three roots in teeth 36 and 46 was diagnosed in a female patient. Additionally, it was indicated a cone beam computed tomography. Moreover, leukocyte genomic DNA was obtained from a blood sample of the patient to determine her ethnicity through analysis of mitochondrial DNA haplogroups using polymerase chain reaction-length restriction fragment polymorphism (PCR-RFLP). Results: Both molars had three roots, 1 mesial (M), 1 distolingual (DL), also known as radix entomolaris (RE), and a distovestibular (DV). For both teeth, M root had 2 canals, and DV and DL roots presented just 1 canal. Mitochondrial DNA analysis determined presence of haplogroup C, corresponding to Amerindian ethnicity. Conclusions: The presence of RE is uncommon. This case report contributes to describe this rare anatomical variation. To our knowledge, this is the first molecular-genetic study applied to dental anatomy and gives basis to develop future research in the area
VLA observations of candidate high-mass protostellar objects at 7 mm
We present radio continuum observations at 7 mm made using the Very Large
Array towards three massive star forming regions thought to be in very early
stages of evolution selected from the sample of Sridharan et al. (2002).
Emission was detected towards all three sources (IRAS 18470-0044, IRAS
19217+1651 and IRAS 23151+5912). We find that in all cases the 7 mm emission
corresponds to thermal emission from ionized gas. The regions of ionized gas
associated with IRAS 19217+1651 and IRAS 23151+5912 are hypercompact with
diameters of 0.009 and 0.0006 pc, and emission measures of 7.0 x 10^8 and 2.3 x
10^9 pc cm^(-6), respectively.Comment: 17 pages, 5 figures, accepted by The Astronomical Journa
Radio and IR study of the massive star-forming region IRAS 16353-4636
Context. With the latest infrared surveys, the number of massive protostellar
candidates has increased significantly. New studies have posed additional
questions on important issues about the formation, evolution, and other
phenomena related to them. Complementary to infrared data, radio observations
are a good tool to study the nature of these objects, and to diagnose the
formation stage. Aims. Here we study the far-infrared source IRAS 16353-4636
with the aim of understanding its nature and origin. In particular, we search
for young stellar objects (YSOs), possible outflow structure, and the presence
of non-thermal emission. Methods. Using high-resolution, multi-wavelength radio
continuum data obtained with the Australia Telescope Compact Array, we image
IRAS 16353-4636 and its environment from 1.4 to 19.6 GHz, and derive the
distribution of the spectral index at maximum angular resolution. We also
present new JHKs photometry and spectroscopy data obtained at ESO NTT. 13 CO
and archival HI line data, and infrared databases (MSX, GLIMPSE, MIPSGal) are
also inspected. Results. The radio continuum emission associated with IRAS
16353-4636 was found to be extended (~10 arcsec), with a bow-shaped morphology
above 4.8 GHz, and a strong peak persistent at all frequencies. The NIR
photometry led us to identify ten near-IR sources and classify them according
to their color. We used the HI line data to derive the source distance, and
analyzed the kinematical information from the CO and NIR lines detected.
Conclusions. We have identified the source IRAS 16353-4636 as a new
protostellar cluster. In this cluster we recognized three distinct sources: a
low-mass YSO, a high-mass YSOs, and a mildly confined region of intense and
non-thermal radio emission. We propose the latter corresponds to the terminal
part of an outflow.Comment: To appear in A&A. 10 pages, 8 figure
Preliminary analysis of the diversity of Chironomidae (Diptera) present in water courses in Catamarca
The diversity of Chironomidae larvae was studied in two water courses in Catamarca, the Río River and El Simbolar Stream. They are both located in ecoregions, the former in the Puna and the latter in the Chaco Serrano. The aim of this paper was to analyze the diversity of Chironomidae in relation to environmental variables in watercourses in Catamarca. Sampling was performed in periods of high and low water, using a Surber sampler (300 μ and 0.09 m-2).Instituto de Limnología "Dr. Raúl A. Ringuelet
A wide-angle outflow with the simultaneous presence of a high-velocity jet in the high-mass Cepheus A HW2 system
We present five epochs of VLBI water maser observations around the massive
protostar Cepheus A HW2 with 0.4 mas (0.3 AU) resolution. The main goal of
these observations was to follow the evolution of the remarkable water maser
linear/arcuate structures found in earlier VLBI observations. Comparing the
data of our new epochs of observation with those observed five years before, we
find that at "large" scales of > 1" (700 AU) the main regions of maser emission
persist, implying that both the surrounding medium and the exciting sources of
the masers have been relatively stable during that time span. However, at
smaller scales of < 0.1" (70 AU) we see large changes in the maser structures,
particularly in the expanding arcuate structures R4 and R5. R4 traces a nearly
elliptical patchy ring of ~ 70 mas size (50 AU) with expanding motions of ~ 5
mas/yr (15 km/s). This structure is probably driven by the wind of a still
unidentified YSO located at the centre of the ring (~ 0.18" south of HW2). On
the other hand, the R5 expanding bubble structure (driven by the wind of a
previously identified YSO located ~ 0.6" south of HW2) is currently dissipating
in the circumstellar medium and losing its previous degree of symmetry,
indicating a very short-lived event. In addition, our results reveal, at scales
of ~ 1" (700 AU), the simultaneous presence of a relatively slow (~ 10-70 km/s)
wide-angle outflow (opening angle of ~ 102 deg, traced by the masers, and the
fast (~ 500~km/s) highly collimated radio jet associated with HW2 (opening
angle of ~ 18 deg, previously observed with the VLA. This simultaneous presence
of a wide-angle outflow and a highly collimated jet associated with a massive
protostar is similar to what is found in some low-mass YSOs. The implications
of these results in the study of the formation of high-mass stars are
discussed.Comment: 28 pages, 7 figures. Animations will be included as supporting
material online (MNRAS web page
Whole-Blood Mitochondrial DNA Copies Are Associated With the Prognosis of Acute Respiratory Distress Syndrome After Sepsis.
https://pubmed.ncbi.nlm.nih.gov/34557198/#:~:text=Resumen-,El%20s%C3%ADndrome%20de%20dificultad%20respiratoria%20aguda%20(SDRA)%20es%20un%20proceso,v%C3%ADnculos%20mec%C3%A1nicos%20de%20esta%20observaci%C3%B3n%20con%20la%20patogenia%20del%20SDRA.,-Palabras%20clave%3A%20SDR
Ursodeoxycholate reduces ethinylestradiol glucuronidation in the rat: Role of prevention in estrogen-induced cholestasis
ABSTRACT Ethinylestradiol (EE) administration (5 mg/kg, s.c., daily for 5 days) to rats leads to cholestasis, and its derivative EE 17-glucuronide is a likely mediator of this effect. Coadministration of ursodeoxycholate (UDC) was shown to prevent ethinylestradiol-induced cholestasis. The aim of this study was to evaluate the inhibitory effect of UDC on EE glucuronidation in vivo and in vitro as a potential mechanism to explain UDC protection. UDC treatment (25 mg/kg, i.p., daily for 5 days) decreased the biliary excretion of EE 17-glucuronide in bile after administration of a trace dose of [ 3 H]EE and reduced microsomal EE 17-glucuronidation activity by 20% and expression of UGT2B1, one of the enzymes involved in EE conjugation, by 30%. Glucuronidation kinetic studies were performed in vitro using normal microsomes and isolated hepatocytes in the presence of tauroursodeoxycholate (TUDC), the major endogenous derivative of UDC in the rat. Kinetic enzymatic studies in microsomes showed a noncompetitive inhibition of EE 17-glucuronidation by TUDC, which was unique for this bile salt since other endogenous bile salts such as taurocholate, taurochenodeoxycholate, or taurodeoxycholate did not affect the enzyme activity. Studies in isolated hepatocytes confirmed the inhibitory effect of TUDC on EE glucuronidation and indicated that TUDC can reach the enzyme active site in intact cells. In conclusion, both in vivo and in vitro experiments indicate that UDC decreased the metabolic pathways involved in EE glucuronidation, hence decreasing the formation of the cholestatic derivative EE 17-glucuronide
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