2,505 research outputs found
Star Formation Under the Outflow: The Discovery of a Non-Thermal Jet from OMC-2 FIR 3 and its Relationship to the Deeply Embedded FIR 4 Protostar
We carried out multiwavelength (0.7-5 cm), multiepoch (1994-2015) Very Large
Array (VLA) observations toward the region enclosing the bright far-IR sources
FIR 3 (HOPS 370) and FIR 4 (HOPS 108) in OMC-2. We report the detection of 10
radio sources, seven of them identified as young stellar objects. We image a
well-collimated radio jet with a thermal free-free core (VLA 11) associated
with the Class I intermediate-mass protostar HOPS 370. The jet presents several
knots (VLA 12N, 12C, 12S) of non-thermal radio emission (likely synchrotron
from shock-accelerated relativistic electrons) at distances of ~7,500-12,500 au
from the protostar, in a region where other shock tracers have been previously
identified. These knots are moving away from the HOPS 370 protostar at ~ 100
km/s. The Class 0 protostar HOPS 108, which itself is detected as an
independent, kinematically decoupled radio source, falls in the path of these
non-thermal radio knots. These results favor the previously proposed scenario
where the formation of HOPS 108 has been triggered by the impact of the HOPS
370 outflow with a dense clump. However, HOPS 108 presents a large proper
motion velocity of ~ 30 km/s, similar to that of other runaway stars in Orion,
whose origin would be puzzling within this scenario. Alternatively, an apparent
proper motion could result because of changes in the position of the centroid
of the source due to blending with nearby extended emission, variations in the
source shape, and /or opacity effects.Comment: 16 pages, 4 figures, accepted for publication in The Astrophysical
Journa
Imaging the Inner and Outer Gaps of the Pre-Transitional Disk of HD 169142 at 7 mm
We present Very Large Array observations at 7 mm that trace the thermal
emission of large dust grains in the HD 169142 protoplanetary disk. Our images
show a ring of enhanced emission of radius ~25-30 AU, whose inner region is
devoid of detectable 7 mm emission. We interpret this ring as tracing the rim
of an inner cavity or gap, possibly created by a planet or a substellar
companion. The ring appears asymmetric, with the western part significantly
brighter than the eastern one. This azimuthal asymmetry is reminiscent of the
lopsided structures that are expected to be produced as a consequence of
trapping of large dust grains. Our observations also reveal an outer annular
gap at radii from ~40 to ~70 AU. Unlike other sources, the radii of the inner
cavity, the ring, and the outer gap observed in the 7 mm images, which trace
preferentially the distribution of large (mm/cm sized) dust grains, coincide
with those obtained from a previous near-infrared polarimetric image, which
traces scattered light from small (micron- sized) dust grains. We model the
broad-band spectral energy distribution and the 7 mm images to constrain the
disk physical structure. From this modeling we infer the presence of a small
(radius ~0.6 AU) residual disk inside the central cavity, indicating that the
HD 169142 disk is a pre-transitional disk. The distribution of dust in three
annuli with gaps in between them suggests that the disk in HD 169142 is being
disrupted by at least two planets or substellar objects.Comment: Accepted by ApJ Letters, 16 pages, 3 figures, ApJ Letters 201
Differential cognitive impairment for diverse forms of multiple sclerosis
BACKGROUND: Cognitive impairment is a common feature in multiple sclerosis (MS) patients and occurs in 60% of all cases. Unfortunately, neurological examination does not always agree with the neuropsychological evaluation in determining the cognitive profile of the patient. On the other hand, psychophysiological techniques such as event-related potentials (ERPs) can help in evaluating cognitive impairment in different pathologies. Behavioural responses and EEG signals were recorded during the experiment in three experimental groups: 1) a relapsing-remitting group (RRMS), 2) a benign multiple sclerosis group (BMS) and 3) a Control group. The paradigm employed was a spatial attention task with central cues (Posner experiment). The main aim was to observe the differences in the performance (behavioural variables) and in the latency and amplitude of the ERP components among these groups. RESULTS: Our data indicate that both MS groups showed poorer task performance (longer reaction times and lower percentage of correct responses), a latency delay for the N1 and P300 component, and a different amplitude for the frontal N1. Moreover, the deficit in the BMS group, indexed by behavioural and pyschophysiological variables, was more pronounced compared to the RRMS group. CONCLUSION: The present results suggest a cognitive impairment in the information processing in all of these patients. Comparing both pathological groups, cognitive impairment was more accentuated in the BMS group compared to the RMSS group. This suggests a silent deterioration of cognitive skills for the BMS that is not usually treated with pharmacological or neuropsychological therapy
Multidrug transporter MRP4/ABCC4 as a key determinant of pancreatic cancer aggressiveness
Recent findings show that MRP4 is critical for pancreatic ductal adenocarcinoma (PDAC) cell proliferation. Nevertheless, the significance of MRP4 protein levels and function in PDAC progression is still unclear. The aim of this study was to determine the role of MRP4 in PDAC tumor aggressiveness. Bioinformatic studies revealed that PDAC samples show higher MRP4 transcript levels compared to normal adjacent pancreatic tissue and circulating tumor cells express higher levels of MRP4 than primary tumors. Also, high levels of MRP4 are typical of high-grade PDAC cell lines and associate with an epithelial-mesenchymal phenotype. Moreover, PDAC patients with high levels of MRP4 depict dysregulation of pathways associated with migration, chemotaxis and cell adhesion. Silencing MRP4 in PANC1 cells reduced tumorigenicity and tumor growth and impaired cell migration. Transcriptomic analysis revealed that MRP4 silencing alters PANC1 gene expression, mainly dysregulating pathways related to cell-to-cell interactions and focal adhesion. Contrarily, MRP4 overexpression significantly increased BxPC-3 growth rate, produced a switch in the expression of EMT markers, and enhanced experimental metastatic incidence. Altogether, our results indicate that MRP4 is associated with a more aggressive phenotype in PDAC, boosting pancreatic tumorigenesis and metastatic capacity, which could finally determine a fast tumor progression in PDAC patients.Fil: Sahores, Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Carozzo, A.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: May, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Gomez, Natalia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Di Siervi, Nicolás. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: de Sousa Serro, Maximiliano Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Yaneff, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; ArgentinaFil: Rodriguez Gonzalez, Angela Paola. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Abba, Martín Carlos. Universidad Nacional de La Plata. Facultad de Ciencias Médicas. Centro de Investigaciones Inmunológicas Básicas y Aplicadas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Shayo, Carina Claudia. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Davio, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Farmacológicas. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Instituto de Investigaciones Farmacológicas; Argentin
Three years of harvest with the vector vortex coronagraph in the thermal infrared
For several years, we have been developing vortex phase masks based on
sub-wavelength gratings, known as Annular Groove Phase Masks. Etched onto
diamond substrates, these AGPMs are currently designed to be used in the
thermal infrared (ranging from 3 to 13 {\mu}m). Our AGPMs were first installed
on VLT/NACO and VLT/VISIR in 2012, followed by LBT/LMIRCam in 2013 and
Keck/NIRC2 in 2015. In this paper, we review the development, commissioning,
on-sky performance, and early scientific results of these new coronagraphic
modes and report on the lessons learned. We conclude with perspectives for
future developments and applications.Comment: To appear in SPIE proceedings vol. 990
An SiO Toroid and Wide-angle Outflow associated with the Massive Protostar W75N(B)-VLA2
We have carried out ALMA observations of the massive star-forming region
W75N(B), which contains the massive protostars VLA1, VLA2, and VLA3.
Particularly, VLA2 is an enigmatic protostar associated with a wind-driven
HO maser shell, which has evolved from an almost isotropic outflow to a
collimated one in just 20 years. The shell expansion seemed to be halted by an
obstacle located to the northeast of VLA2. Here we present our findings from
observing the 1.3 mm continuum and HCO and SiO emission lines. Within a
region of ( au) diameter, we have detected 40 compact
mm-continuum sources, three of them coinciding with VLA1, VLA2, and VLA3. While
the HCO emission is mainly distributed in a fragmented structure around the
three massive protostars, but without any of the main HCO clumps spatially
coinciding with them, the SiO is highly concentrated on VLA2, indicating the
presence of very strong shocks generated near this protostar. The SiO emission
is clearly resolved into an elongated structure (; au390 au) perpendicular to the major axis of the wind-driven maser
shell. The structure and kinematics of the SiO emission are consistent with a
toroid and a wide-angle outflow surrounding a central mass of
M, thus supporting previous theoretical predictions regarding the
evolution of the outflow. Additionally, we have identified the expected
location and estimated the gas density of the obstacle that is hindering the
expansion of the maser shell.Comment: To be published in The Astrophysical Journal Letters. Sixteen pages,
seven figures. Updated metadat
Neutrino Masses and Mixings from Supersymmetry with Bilinear R--Parity Violation: A Theory for Solar and Atmospheric Neutrino Oscillations
The simplest unified extension of the MSSM with bi-linear R--Parity violation
naturally predicts a hierarchical neutrino mass spectrum, in which one neutrino
acquires mass by mixing with neutralinos, while the other two get mass
radiatively. We have performed a full one-loop calculation of the
neutralino-neutrino mass matrix in the bi-linear \rp MSSM, taking special care
to achieve a manifestly gauge invariant calculation. Moreover we have performed
the renormalization of the heaviest neutrino, needed in order to get meaningful
results. The atmospheric mass scale and maximal mixing angle arise from
tree-level physics, while solar neutrino scale and oscillations follow from
calculable one-loop corrections. If universal supergravity assumptions are made
on the soft-supersymmetry breaking terms then the atmospheric scale is
calculable as a function of a single \rp violating parameter by the
renormalization group evolution due to the non-zero bottom quark Yukawa
coupling. The solar neutrino problem must be accounted for by the small mixing
angle (SMA) MSW solution. If these assumptions are relaxed then one can
implement large mixing angle solutions, either MSW or just-so. The theory
predicts the lightest supersymmetic particle (LSP) decay to be observable at
high-energy colliders, despite the smallness of neutrino masses indicated by
experiment. This provides an independent way to test this solution of the
atmospheric and solar neutrino anomalies.Comment: 46 pages, references added + several misprints correcte
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