2,102 research outputs found
CRIRES-VLT high-resolution spectro-astrometry as a tool in the search of small structures at the cores of Planetary Nebulae
The onset of the asymmetry in planetary nebulae (PNe) occurs during the short
transition between the end of the asymptotic giant branch (AGB) phase and the
beginning of the PN phase. Sources in this transition phase are compact and
emit intensely in infrared wavelengths, making high spatial resolution
observations in the infrared mandatory to investigate the shaping process of
PNe. Interferometric VLTI IR observations have revealed compelling evidence of
disks at the cores of PNe, but the limited sensitivity, strong observational
constraints, and limited spatial coverage place severe limits on the universal
use of this technique. Inspired by the successful detection of proto-planetary
disks using spectro-astrometric observations, we apply here for the first time
this technique to search for sub-arcsecond structures in PNe. Our exploratory
study using CRIRES (CRyogenic high-resolution Infra-Red Echelle Spectrograph)
commissioning data of the proto-PN IRAS 17516-2525 and the young PN SwSt 1 has
revealed small-sized structures after the spectro-astrometric analysis of the
two sources. In IRAS 17516-2525, the spectro-astrometric signal has a size of
only 12 mas, as detected in the Brackett-gamma line, whereas the structures
found in SwSt 1 have sizes of 230 mas in the [Fe III] line and 130 mas in the
Brackett-gamma line. The spectroscopic observations required to perform
spectro-astrometry of sources in the transition towards the PN phase are less
time consuming and much more sensitive than VLTI IR observations. The results
presented here open a new window in the search of the small-sized collimating
agents that shape the complex morphologies of extremely axisymmetric PNe.Comment: 6 pages, 4 figure
VISIR-VLT Images of the Water Maser Emitting Planetary Nebula K 3-35
K3-35 is an extremely young bipolar planetary nebula that contains a
precessing bipolar jet and a small (radius 80 AU) water maser equatorial ring.
We have obtained VISIR- VLT images of K 3-35 in the PAH1 ({\lambda}=8.6
{\mu}m), [S iv] ({\lambda}=10.6 {\mu}m), and SiC ({\lambda}=11.85 {\mu}m)
filters to analize the mid-IR morphology and the temperature structure of its
dust emission. The images show the innermost nebular regions undetected at
optical wavelegths and the precessing bipolar jets. The temperature map shows
variations in the temperature in the equatorial zone and in regions associated
to its jets.Comment: 2 pages, 2 figures, 283 IAU Symp. Planetary Nebulae an Eye to the
Futur
From food waste to volatile fatty acids towards a circular economy
The food industrial sector generates large amounts of waste, which are often used for animal feed, for agriculture or landfilled. However, these wastes have a very reach composition in carbon and other compounds, which make them very attractive for valorization through biotechnological processes. Added value compounds, such as volatile fatty acids (VFAs), can be produced by anaerobic fermentation using pure cultures or mixed microbial cultures and food waste as carbon source. Research on valuable applications for VFAs, such as polyhydroxyalkanoates, bioenergy or biological nutrient removal, towards a circular economy is emerging. This enhances the sustainability and the economic value of food waste. This chapter reviews the various types of food waste used for VFAs production using mixed microbial cultures, the anaerobic processes, involved and the main applications for the produced VFAs. The main parameters affecting VFAs production are also discussed.publishersversionpublishe
Evidence for reduced magnetic braking in polars from binary population models
We present the first population synthesis of synchronous magnetic cataclysmic variables, called polars, taking into account the effect of the white dwarf (WD) magnetic field on angular momentum loss. We implemented the reduced magnetic braking (MB) model proposed by Li, Wu & Wickramasinghe into the Binary Stellar Evolution (BSE) code recently calibrated for cataclysmic variable (CV) evolution. We then compared separately our predictions for polars and non-magnetic CVs with a large and homogeneous sample of observed CVs from the Sloan Digital Sky Survey. We found that the predicted orbital period distributions and space densities agree with the observations if period bouncers are excluded. For polars, we also find agreement between predicted and observed mass transfer rates, while the mass transfer rates of non-magnetic CVs with periods ≳3 h drastically disagree with those derived from observations. Our results provide strong evidence that the reduced MB model for the evolution of highly magnetized accreting WDs can explain the observed properties of polars. The remaining main issues in our understanding of CV evolution are the origin of the large number of highly magnetic WDs, the large scatter of the observed mass transfer rates for non-magnetic systems with periods ≳3 h, and the absence of period bouncers in observed samples
The Impact of Simple Institutions in Experimental Economies with Poverty Traps
We introduce an experimental approach to study the effect of institutions on economic growth. In
each period, agents produce and trade output in a market, and allocate it to consumption and
investment. Productivity is higher if total capital stock is above a threshold. The threshold externality
generates two steady states – a suboptimal poverty trap and an optimal steady state. In a baseline
treatment, the economies converge to the poverty trap. However, the ability to make public
announcements or to vote on competing and binding policies, increases output, welfare and capital
stock. Combining these two simple institutions guarantees that the economies escape the poverty
trap
Genomic analyses of microdissected Hodgkin and Reed-Sternberg cells: mutations in epigenetic regulators and p53 are frequent in refractory classic Hodgkin lymphoma
This work was supported by grants from the Plan Nacional de I + D + I cofinanced
by the ISCIII-Subdirección General de Evaluación and the Fondo
Europeo de Desarrollo Regional (FEDER), PI12/1832, the Spanish Association for
Cancer Research (AECC), and Programas para Grupos de Investigación de la
Comunidad Autónoma de Madrid (Biomedicina 2017)
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